Human mitochondrial genetics – Wikipedia

Human mitochondrial genetics is the study of the genetics of human mitochondrial DNA (the DNA contained in human mitochondria). The human mitochondrial genome is the entirety of hereditary information contained in human mitochondria. Mitochondria are small structures in cells that generate energy for the cell to use, and are hence referred to as the “powerhouses” of the cell.

Mitochondrial DNA (mtDNA) is not transmitted through nuclear DNA (nDNA). In humans, as in most multicellular organisms, mitochondrial DNA is inherited only from the mother’s ovum. There are theories, however, that paternal mtDNA transmission in humans can occur under certain circumstances.[1]

Mitochondrial inheritance is therefore non-Mendelian, as Mendelian inheritance presumes that half the genetic material of a fertilized egg (zygote) derives from each parent.

Eighty percent of mitochondrial DNA codes for mitochondrial RNA, and therefore most mitochondrial DNA mutations lead to functional problems, which may be manifested as muscle disorders (myopathies).

Because they provide 30 molecules of ATP per glucose molecule in contrast to the 2 ATP molecules produced by glycolysis, mitochondria are essential to all higher organisms for sustaining life. The mitochondrial diseases are genetic disorders carried in mitochondrial DNA, or nuclear DNA coding for mitochondrial components. Slight problems with any one of the numerous enzymes used by the mitochondria can be devastating to the cell, and in turn, to the organism.

In humans, mitochondrial DNA (mtDNA) forms closed circular molecules that contain 16,569[2][3] DNA base pairs,[4] with each such molecule normally containing a full set of the mitochondrial genes. Each human mitochondrion contains, on average, approximately 5 such mtDNA molecules, with the quantity ranging between 1 and 15.[4] Each human cell contains approximately 100 mitochondria, giving a total number of mtDNA molecules per human cell of approximately 500.[4]

Because mitochondrial diseases (diseases due to malfunction of mitochondria) can be inherited both maternally and through chromosomal inheritance, the way in which they are passed on from generation to generation can vary greatly depending on the disease. Mitochondrial genetic mutations that occur in the nuclear DNA can occur in any of the chromosomes (depending on the species). Mutations inherited through the chromosomes can be autosomal dominant or recessive and can also be sex-linked dominant or recessive. Chromosomal inheritance follows normal Mendelian laws, despite the fact that the phenotype of the disease may be masked.

Because of the complex ways in which mitochondrial and nuclear DNA “communicate” and interact, even seemingly simple inheritance is hard to diagnose. A mutation in chromosomal DNA may change a protein that regulates (increases or decreases) the production of another certain protein in the mitochondria or the cytoplasm; this may lead to slight, if any, noticeable symptoms. On the other hand, some devastating mtDNA mutations are easy to diagnose because of their widespread damage to muscular, neural, and/or hepatic tissues (among other high-energy and metabolism-dependent tissues) and because they are present in the mother and all the offspring.

Mitochondrial genome mutations are passed on 100% of the time from mother to all her offspring. So, if a female has a mitochondrial trait, all offspring inherit it. However, if a male has a mitochondrial trait, no offspring inherit it.The number of affected mtDNA molecules inherited by a specific offspring can vary greatly because

It is possible, even in twin births, for one baby to receive more than half mutant mtDNA molecules while the other twin may receive only a tiny fraction of mutant mtDNA molecules with respect to wildtype (depending on how the twins divide from each other and how many mutant mitochondria happen to be on each side of the division). In a few cases, some mitochondria or a mitochondrion from the sperm cell enters the oocyte but paternal mitochondria are actively decomposed.

Genes in the human mitochondrial genome are as follows.

It was originally incorrectly believed that the mitochondrial genome contained only 13 protein-coding genes, all of them encoding proteins of the electron transport chain. However, in 2001, a 14th biologically active protein called humanin was discovered, and was found to be encoded by the mitochondrial gene MT-RNR2 which also encodes part of the mitochondrial ribosome (made out of RNA):

Unlike the other proteins, humanin does not remain in the mitochondria, and interacts with the rest of the cell and cellular receptors. Humanin can protect brain cells by inhibiting apoptosis. Despite its name, versions of humanin also exist in other animals, such as rattin in rats.

The following genes encode rRNAs:

The following genes encode tRNAs:

Mitochondrial DNA had traditionally had the two strand of the DNA designated the heavy and the light strand, due to their boyant densities during separation in cesium chloride gradients[5][6], which was found to be related to the relative G+T nucleotide content of the strand[7]. However, confusion of labeling of this strands is widespread, and appears to originate with a identification of the majority coding strand as the heavy in one influential article in 1999[8][7]. In humans, the light strand of mtDNA carries 28 genes and the heavy strand of mtDNA carries only 9 genes.[7][9] Eight of the 9 genes on the heavy strand code for mitochondrial tRNA molecules. Human mtDNA consists of 16,569 nucleotide pairs. The entire molecule is regulated by only one regulatory region which contains the origins of replication of both heavy and light strands. The entire human mitochondrial DNA molecule has been mapped[1][2].

The genetic code is, for the most part, universal, with few exceptions: mitochondrial genetics includes some of these. For most organisms the “stop codons” are “UAA”, “UAG”, and “UGA”. In vertebrate mitochondria “AGA” and “AGG” are also stop codons, but not “UGA”, which codes for tryptophan instead. “AUA” codes for isoleucine in most organisms but for methionine in vertebrate mitochondrial mRNA.

There are many other variations among the codes used by other mitochondrial m/tRNA, which happened not to be harmful to their organisms, and which can be used as a tool (along with other mutations among the mtDNA/RNA of different species) to determine relative proximity of common ancestry of related species. (The more related two species are, the more mtDNA/RNA mutations will be the same in their mitochondrial genome).

Using these techniques, it is estimated that the first mitochondria arose around 1.5 billion years ago. A generally accepted hypothesis is that mitochondria originated as an aerobic prokaryote in a symbiotic relationship within an anaerobic eukaryote.

Mitochondrial replication is controlled by nuclear genes and is specifically suited to make as many mitochondria as that particular cell needs at the time.

Mitochondrial transcription in humans is initiated from three promoters, H1, H2, and L (heavy strand 1, heavy strand 2, and light strand promoters). The H2 promoter transcribes almost the entire heavy strand and the L promoter transcribes the entire light strand. The H1 promoter causes the transcription of the two mitochondrial rRNA molecules.[10]

When transcription takes place on the heavy strand a polycistronic transcript is created. The light strand produces either small transcripts, which can be used as primers, or one long transcript. The production of primers occurs by processing of light strand transcripts with the Mitochondrial RNase MRP (Mitochondrial RNA Processing). The requirement of transcription to produce primers links the process of transcription to mtDNA replication. Full length transcripts are cut into functional tRNA, rRNA, and mRNA molecules.[citation needed]

The process of transcription initiation in mitochondria involves three types of proteins: the mitochondrial RNA polymerase (POLRMT), mitochondrial transcription factor A (TFAM), and mitochondrial transcription factors B1 and B2 (TFB1M, TFB2M). POLRMT, TFAM, and TFB1M or TFB2M assemble at the mitochondrial promoters and begin transcription. The actual molecular events that are involved in initiation are unknown, but these factors make up the basal transcription machinery and have been shown to function in vitro.[citation needed]

Mitochondrial translation is still not very well understood. In vitro translations have still not been successful, probably due to the difficulty of isolating sufficient mt mRNA, functional mt rRNA, and possibly because of the complicated changes that the mRNA undergoes before it is translated.[citation needed]

The Mitochondrial DNA Polymerase (Pol gamma, encoded by the POLG gene) is used in the copying of mtDNA during replication. Because the two (heavy and light) strands on the circular mtDNA molecule have different origins of replication, it replicates in a D-loop mode. One strand begins to replicate first, displacing the other strand. This continues until replication reaches the origin of replication on the other strand, at which point the other strand begins replicating in the opposite direction. This results in two new mtDNA molecules. Each mitochondrion has several copies of the mtDNA molecule and the number of mtDNA molecules is a limiting factor in mitochondrial fission. After the mitochondrion has enough mtDNA, membrane area, and membrane proteins, it can undergo fission (very similar to that which bacteria use) to become two mitochondria. Evidence suggests that mitochondria can also undergo fusion and exchange (in a form of crossover) genetic material among each other. Mitochondria sometimes form large matrices in which fusion, fission, and protein exchanges are constantly occurring. mtDNA shared among mitochondria (despite the fact that they can undergo fusion).[citation needed]

Mitochondrial DNA is susceptible to damage from free oxygen radicals from mistakes that occur during the production of ATP through the electron transport chain. These mistakes can be caused by genetic disorders, cancer, and temperature variations. These radicals can damage mtDNA molecules or change them, making it hard for mitochondrial polymerase to replicate them. Both cases can lead to deletions, rearrangements, and other mutations. Recent evidence has suggested that mitochondria have enzymes that proofread mtDNA and fix mutations that may occur due to free radicals. It is believed that a DNA recombinase found in mammalian cells is also involved in a repairing recombination process. Deletions and mutations due to free radicals have been associated with the aging process. It is believed that radicals cause mutations which lead to mutant proteins, which in turn led to more radicals. This process takes many years and is associated with some aging processes involved in oxygen-dependent tissues such as brain, heart, muscle, and kidney. Auto-enhancing processes such as these are possible causes of degenerative diseases including Parkinson’s, Alzheimer’s, and coronary artery disease.[citation needed]

Because mitochondrial growth and fission are mediated by the nuclear DNA, mutations in nuclear DNA can have a wide array of effects on mtDNA replication. Despite the fact that the loci for some of these mutations have been found on human chromosomes, specific genes and proteins involved have not yet been isolated. Mitochondria need a certain protein to undergo fission. If this protein (generated by the nucleus) is not present, the mitochondria grow but they do not divide. This leads to giant, inefficient mitochondria. Mistakes in chromosomal genes or their products can also affect mitochondrial replication more directly by inhibiting mitochondrial polymerase and can even cause mutations in the mtDNA directly and indirectly. Indirect mutations are most often caused by radicals created by defective proteins made from nuclear DNA.[citation needed]

In total, the mitochondrion hosts about 3000 different types of proteins, but only about 13 of them are coded on the mitochondrial DNA. Most of the 3000 types of proteins are involved in a variety of processes other than ATP production, such as porphyrin synthesis. Only about 3% of them code for ATP production proteins. This means most of the genetic information coding for the protein makeup of mitochondria is in chromosomal DNA and is involved in processes other than ATP synthesis. This increases the chances that a mutation that will affect a mitochondrion will occur in chromosomal DNA, which is inherited in a Mendelian pattern. Another result is that a chromosomal mutation will affect a specific tissue due to its specific needs, whether those may be high energy requirements or a need for the catabolism or anabolism of a specific neurotransmitter or nucleic acid. Because several copies of the mitochondrial genome are carried by each mitochondrion (210 in humans), mitochondrial mutations can be inherited maternally by mtDNA mutations which are present in mitochondria inside the oocyte before fertilization, or (as stated above) through mutations in the chromosomes.[citation needed]

Mitochondrial diseases range in severity from asymptomatic to fatal, and are most commonly due to inherited rather than acquired mutations of mitochondrial DNA. A given mitochondrial mutation can cause various diseases depending on the severity of the problem in the mitochondria and the tissue the affected mitochondria are in. Conversely, several different mutations may present themselves as the same disease. This almost patient-specific characterization of mitochondrial diseases (see Personalized medicine) makes them very hard to accurately recognize, diagnose and trace. Some diseases are observable at or even before birth (many causing death) while others do not show themselves until late adulthood (late-onset disorders). This is because the number of mutant versus wildtype mitochondria varies between cells and tissues, and is continuously changing. Because cells have multiple mitochondria, different mitochondria in the same cell can have different variations of the mtDNA. This condition is referred to as heteroplasmy. When a certain tissue reaches a certain ratio of mutant versus wildtype mitochondria, a disease will present itself. The ratio varies from person to person and tissue to tissue (depending on its specific energy, oxygen, and metabolism requirements, and the effects of the specific mutation). Mitochondrial diseases are very numerous and different. Apart from diseases caused by abnormalities in mitochondrial DNA, many diseases are suspected to be associated in part by mitochondrial dysfunctions, such as diabetes mellitus, forms of cancer and cardiovascular disease, lactic acidosis, specific forms of myopathy, osteoporosis, Alzheimer’s disease, Parkinsons’s disease, stroke, male infertility and which are also believed to play a role in the aging process.[citation needed]

Human mtDNA can also be used to help identify individuals.[11] Forensic laboratories occasionally use mtDNA comparison to identify human remains, and especially to identify older unidentified skeletal remains. Although unlike nuclear DNA, mtDNA is not specific to one individual, it can be used in combination with other evidence (anthropological evidence, circumstantial evidence, and the like) to establish identification. mtDNA is also used to exclude possible matches between missing persons and unidentified remains.[12] Many researchers believe that mtDNA is better suited to identification of older skeletal remains than nuclear DNA because the greater number of copies of mtDNA per cell increases the chance of obtaining a useful sample, and because a match with a living relative is possible even if numerous maternal generations separate the two. American outlaw Jesse James’s remains were identified using a comparison between mtDNA extracted from his remains and the mtDNA of the son of the female-line great-granddaughter of his sister.[13] Similarly, the remains of Alexandra Feodorovna (Alix of Hesse), last Empress of Russia, and her children were identified by comparison of their mitochondrial DNA with that of Prince Philip, Duke of Edinburgh, whose maternal grandmother was Alexandra’s sister Victoria of Hesse.[14] Similarly to identify Emperor Nicholas II remains his mitochondrial DNA was compared with that of James Carnegie, 3rd Duke of Fife, whose maternal great-grandmother Alexandra of Denmark (Queen Alexandra) was sister of Nicholas II mother Dagmar of Denmark (Empress Maria Feodorovna).[15]

Read the original post:

Human mitochondrial genetics – Wikipedia

Vogel and Motulsky’s Human Genetics: Problems and …

Thefourth, completely revised edition of this classic reference and textbook presents a cohesive and up-to-date exposition of the concepts, results, and problems underlying theory and practice in human and medical genetics. In the 10 years since the appearance of thethird edition, many new insights have emerged for understanding the genetic basis of development and function in human health and disease. Human genetics, with its emphasis on molecular concepts and techniques, has become a key discipline in medicine and the biomedical sciences.

The fourth edition has been extensively expanded by new chapters on timely topics such as epigenetics, pharmacogenetics, gene therapy, cloning, andgenetic epidemiology, and databases forbasic and clinical genetics. In addition amulti/chapter section giving an overview on the main model organisms (mouse, dog,worm, fly, fish) used in human genetics research has been introduced.

This book will be of interest to human and medical geneticists, scientists in all biomedical sciences, physicians and epidemiologists, as well as to graduate and postgraduate students who desire to learn the fundamentals of this fascinating field.

Here is the original post:

Vogel and Motulsky’s Human Genetics: Problems and …

Human genetics | biology |

Human genetics, study of the inheritance of characteristics by children from parents. Inheritance in humans does not differ in any fundamental way from that in other organisms.

The study of human heredity occupies a central position in genetics. Much of this interest stems from a basic desire to know who humans are and why they are as they are. At a more practical level, an understanding of human heredity is of critical importance in the prediction, diagnosis, and treatment of diseases that have a genetic component. The quest to determine the genetic basis of human health has given rise to the field of medical genetics. In general, medicine has given focus and purpose to human genetics, so the terms medical genetics and human genetics are often considered synonymous.

Read More on This Topic

genetics: Human genetics

Some geneticists specialize in the hereditary processes of human genetics. Most of the emphasis is on understanding and treating genetic disease and genetically influenced ill health, areas collectively known as medical genetics. One broad area of activity is laboratory research dealing with the

A new era in cytogenetics, the field of investigation concerned with studies of the chromosomes, began in 1956 with the discovery by Jo Hin Tjio and Albert Levan that human somatic cells contain 23 pairs of chromosomes. Since that time the field has advanced with amazing rapidity and has demonstrated that human chromosome aberrations rank as major causes of fetal death and of tragic human diseases, many of which are accompanied by mental retardation. Since the chromosomes can be delineated only during mitosis, it is necessary to examine material in which there are many dividing cells. This can usually be accomplished by culturing cells from the blood or skin, since only the bone marrow cells (not readily sampled except during serious bone marrow disease such as leukemia) have sufficient mitoses in the absence of artificial culture. After growth, the cells are fixed on slides and then stained with a variety of DNA-specific stains that permit the delineation and identification of the chromosomes. The Denver system of chromosome classification, established in 1959, identified the chromosomes by their length and the position of the centromeres. Since then the method has been improved by the use of special staining techniques that impart unique light and dark bands to each chromosome. These bands permit the identification of chromosomal regions that are duplicated, missing, or transposed to other chromosomes.

Micrographs showing the karyotypes (i.e., the physical appearance of the chromosome) of a male and a female have been produced. In a typical micrograph the 46 human chromosomes (the diploid number) are arranged in homologous pairs, each consisting of one maternally derived and one paternally derived member. The chromosomes are all numbered except for the X and the Y chromosomes, which are the sex chromosomes. In humans, as in all mammals, the normal female has two X chromosomes and the normal male has one X chromosome and one Y chromosome. The female is thus the homogametic sex, as all her gametes normally have one X chromosome. The male is heterogametic, as he produces two types of gametesone type containing an X chromosome and the other containing a Y chromosome. There is good evidence that the Y chromosome in humans, unlike that in Drosophila, is necessary (but not sufficient) for maleness.

A human individual arises through the union of two cells, an egg from the mother and a sperm from the father. Human egg cells are barely visible to the naked eye. They are shed, usually one at a time, from the ovary into the oviducts (fallopian tubes), through which they pass into the uterus. Fertilization, the penetration of an egg by a sperm, occurs in the oviducts. This is the main event of sexual reproduction and determines the genetic constitution of the new individual.

Human sex determination is a genetic process that depends basically on the presence of the Y chromosome in the fertilized egg. This chromosome stimulates a change in the undifferentiated gonad into that of the male (a testicle). The gonadal action of the Y chromosome is mediated by a gene located near the centromere; this gene codes for the production of a cell surface molecule called the H-Y antigen. Further development of the anatomic structures, both internal and external, that are associated with maleness is controlled by hormones produced by the testicle. The sex of an individual can be thought of in three different contexts: chromosomal sex, gonadal sex, and anatomic sex. Discrepancies between these, especially the latter two, result in the development of individuals with ambiguous sex, often called hermaphrodites. The phenomenon of homosexuality is of uncertain cause and is unrelated to the above sex-determining factors. It is of interest that in the absence of a male gonad (testicle) the internal and external sex anatomy is always female, even in the absence of a female ovary. A female without ovaries will, of course, be infertile and will not experience any of the female developmental changes normally associated with puberty. Such a female will often have Turners syndrome.

If X-containing and Y-containing sperm are produced in equal numbers, then according to simple chance one would expect the sex ratio at conception (fertilization) to be half boys and half girls, or 1 : 1. Direct observation of sex ratios among newly fertilized human eggs is not yet feasible, and sex-ratio data are usually collected at the time of birth. In almost all human populations of newborns, there is a slight excess of males; about 106 boys are born for every100 girls. Throughout life, however, there is a slightly greater mortality of males; this slowly alters the sex ratio until, beyond the age of about 50 years, there is an excess of females. Studies indicate that male embryos suffer a relatively greater degree of prenatal mortality, so the sex ratio at conception might be expected to favour males even more than the 106 : 100 ratio observed at birth would suggest. Firm explanations for the apparent excess of male conceptions have not been established; it is possible that Y-containing sperm survive better within the female reproductive tract, or they may be a little more successful in reaching the egg in order to fertilize it. In any case, the sex differences are small, the statistical expectation for a boy (or girl) at any single birth still being close to one out of two.

During gestationthe period of nine months between fertilization and the birth of the infanta remarkable series of developmental changes occur. Through the process of mitosis, the total number of cells changes from 1 (the fertilized egg) to about 2 1011. In addition, these cells differentiate into hundreds of different types with specific functions (liver cells, nerve cells, muscle cells, etc.). A multitude of regulatory processes, both genetically and environmentally controlled, accomplish this differentiation. Elucidation of the exquisite timing of these processes remains one of the great challenges of human biology.

Immunity is the ability of an individual to recognize the self molecules that make up ones own body and to distinguish them from such nonself molecules as those found in infectious microorganisms and toxins. This process has a prominent genetic component. Knowledge of the genetic and molecular basis of the mammalian immune system has increased in parallel with the explosive advances made in somatic cell and molecular genetics.

There are two major components of the immune system, both originating from the same precursor stem cells. The bursa component provides B lymphocytes, a class of white blood cells that, when appropriately stimulated, differentiate into plasma cells. These latter cells produce circulating soluble proteins called antibodies or immunoglobulins. Antibodies are produced in response to substances called antigens, most of which are foreign proteins or polysaccharides. An antibody molecule can recognize a specific antigen, combine with it, and initiate its destruction. This so-called humoral immunity is accomplished through a complicated series of interactions with other molecules and cells; some of these interactions are mediated by another group of lymphocytes, the T lymphocytes, which are derived from the thymus gland. Once a B lymphocyte has been exposed to a specific antigen, it remembers the contact so that future exposure will cause an accelerated and magnified immune reaction. This is a manifestation of what has been called immunological memory.

The thymus component of the immune system centres on the thymus-derived T lymphocytes. In addition to regulating the B cells in producing humoral immunity, the T cells also directly attack cells that display foreign antigens. This process, called cellular immunity, is of great importance in protecting the body against a variety of viruses as well as cancer cells. Cellular immunity is also the chief cause of the rejection of organ transplants. The T lymphocytes provide a complex network consisting of a series of helper cells (which are antigen-specific), amplifier cells, suppressor cells, and cytotoxic (killer) cells, all of which are important in immune regulation.

One of the central problems in understanding the genetics of the immune system has been in explaining the genetic regulation of antibody production. Immunobiologists have demonstrated that the system can produce well over one million specific antibodies, each corresponding to a particular antigen. It would be difficult to envisage that each antibody is encoded by a separate gene; such an arrangement would require a disproportionate share of the entire human genome. Recombinant DNA analysis has illuminated the mechanisms by which a limited number of immunoglobulin genes can encode this vast number of antibodies.

Each antibody molecule consists of several different polypeptide chainsthe light chains (L) and the longer heavy chains (H). The latter determine to which of five different classes (IgM, IgG, IgA, IgD, or IgE) an immunoglobulin belongs. Both the L and H chains are unique among proteins in that they contain constant and variable parts. The constant parts have relatively identical amino acid sequences in any given antibody. The variable parts, on the other hand, have different amino acid sequences in each antibody molecule. It is the variable parts, then, that determine the specificity of the antibody.

Recombinant DNA studies of immunoglobulin genes in mice have revealed that the light-chain genes are encoded in four separate parts in germ-line DNA: a leader segment (L), a variable segment (V), a joining segment (J), and a constant segment (C). These segments are widely separated in the DNA of an embryonic cell, but in a mature B lymphocyte they are found in relative proximity (albeit separated by introns). The mouse has more than 200 light-chain variable region genes, only one of which will be incorporated into the proximal sequence that codes for the antibody production in a given B lymphocyte. Antibody diversity is greatly enhanced by this system, as the V and J segments rearrange and assort randomly in each B-lymphocyte precursor cell. The mechanisms by which this DNA rearrangement takes place are not clear, but transposons are undoubtedly involved. Similar combinatorial processes take place in the genes that code for the heavy chains; furthermore, both the light-chain and heavy-chain genes can undergo somatic mutations to create new antibody-coding sequences. The net effect of these combinatorial and mutational processes enables the coding of millions of specific antibody molecules from a limited number of genes. It should be stressed, however, that each B lymphocyte can produce only one antibody. It is the B lymphocyte population as a whole that produces the tremendous variety of antibodies in humans and other mammals.

Plasma cell tumours (myelomas) have made it possible to study individual antibodies, since these tumours, which are descendants of a single plasma cell, produce one antibody in abundance. Another method of obtaining large amounts of a specific antibody is by fusing a B lymphocyte with a rapidly growing cancer cell. The resultant hybrid cell, known as a hybridoma, multiplies rapidly in culture. Since the antibodies obtained from hybridomas are produced by clones derived from a single lymphocyte, they are called monoclonal antibodies.

As has been stated, cellular immunity is mediated by T lymphocytes that can recognize infected body cells, cancer cells, and the cells of a foreign transplant. The control of cellular immune reactions is provided by a linked group of genes, known as the major histocompatibility complex (MHC). These genes code for the major histocompatibility antigens, which are found on the surface of almost all nucleated somatic cells. The major histocompatibility antigens were first discovered on the leukocytes (white blood cells) and are therefore usually referred to as the HLA (human leukocyte group A) antigens.

The advent of the transplantation of human organs in the 1950s made the question of tissue compatibility between donor and recipient of vital importance, and it was in this context that the HLA antigens and the MHC were elucidated. Investigators found that the MHC resides on the short arm of chromosome 6, on four closely associated sites designated HLA-A, HLA-B, HLA-C, and HLA-D. Each locus is highly polymorphic; i.e., each is represented by a great many alleles within the human gene pool. These alleles, like those of the ABO blood group system, are expressed in codominant fashion. Because of the large number of alleles at each HLA locus, there is an extremely low probability of any two individuals (other than siblings) having identical HLA genotypes. (Since a person inherits one chromosome 6 from each parent, siblings have a 25 percent probability of having received the same paternal and maternal chromosomes 6 and thus of being HLA matched.)

Although HLA antigens are largely responsible for the rejection of organ transplants, it is obvious that the MHC did not evolve to prevent the transfer of organs from one person to another. Indeed, information obtained from the histocompatibility complex in the mouse (which is very similar in its genetic organization to that of the human) suggests that a primary function of the HLA antigens is to regulate the number of specific cytotoxic T killer cells, which have the ability to destroy virus-infected cells and cancer cells.

More is known about the genetics of the blood than about any other human tissue. One reason for this is that blood samples can be easily secured and subjected to biochemical analysis without harm or major discomfort to the person being tested. Perhaps a more cogent reason is that many chemical properties of human blood display relatively simple patterns of inheritance.

Certain chemical substances within the red blood cells (such as the ABO and MN substances noted above) may serve as antigens. When cells that contain specific antigens are introduced into the body of an experimental animal such as a rabbit, the animal responds by producing antibodies in its own blood.

In addition to the ABO and MN systems, geneticists have identified about 14 blood-type gene systems associated with other chromosomal locations. The best known of these is the Rh system. The Rh antigens are of particular importance in human medicine. Curiously, however, their existence was discovered in monkeys. When blood from the rhesus monkey (hence the designation Rh) is injected into rabbits, the rabbits produce so-called Rh antibodies that will agglutinate not only the red blood cells of the monkey but the cells of a large proportion of human beings as well. Some people (Rh-negative individuals), however, lack the Rh antigen; the proportion of such persons varies from one human population to another. Akin to data concerning the ABO system, the evidence for Rh genes indicates that only a single chromosome locus (called r) is involved and is located on chromosome 1. At least 35 Rh alleles are known for the r location; basically the Rh-negative condition is recessive.

A medical problem may arise when a woman who is Rh-negative carries a fetus that is Rh-positive. The first such child may have no difficulty, but later similar pregnancies may produce severely anemic newborn infants. Exposure to the red blood cells of the first Rh-positive fetus appears to immunize the Rh-negative mother, that is, she develops antibodies that may produce permanent (sometimes fatal) brain damage in any subsequent Rh-positive fetus. Damage arises from the scarcity of oxygen reaching the fetal brain because of the severe destruction of red blood cells. Measures are available for avoiding the severe effects of Rh incompatibility by transfusions to the fetus within the uterus; however, genetic counselling before conception is helpful so that the mother can receive Rh immunoglobulin immediately after her first and any subsequent pregnancies involving an Rh-positive fetus. This immunoglobulin effectively destroys the fetal red blood cells before the mothers immune system is stimulated. The mother thus avoids becoming actively immunized against the Rh antigen and will not produce antibodies that could attack the red blood cells of a future Rh-positive fetus.

Human serum, the fluid portion of the blood that remains after clotting, contains various proteins that have been shown to be under genetic control. Study of genetic influences has flourished since the development of precise methods for separating and identifying serum proteins. These move at different rates under the impetus of an electrical field (electrophoresis), as do proteins from many other sources (e.g., muscle or nerve). Since the composition of a protein is specified by the structure of its corresponding gene, biochemical studies based on electrophoresis permit direct study of tissue substances that are only a metabolic step or two away from the genes themselves.

Electrophoretic studies have revealed that at least one-third of the human serum proteins occur in variant forms. Many of the serum proteins are polymorphic, occurring as two or more variants with a frequency of not less than 1 percent each in a population. Patterns of polymorphic serum protein variants have been used to determine whether twins are identical (as in assessing compatibility for organ transplants) or whether two individuals are related (as in resolving paternity suits). Whether the different forms have a selective advantage is not generally known.

Much attention in the genetics of substances in the blood has been centred on serum proteins called haptoglobins, transferrins (which transport iron), and gamma globulins (a number of which are known to immunize against infectious diseases). Haptoglobins appear to relate to two common alleles at a single chromosome locus; the mode of inheritance of the other two seems more complicated, about 18 kinds of transferrins having been described. Like blood-cell antigen genes, serum-protein genes are distributed worldwide in the human population in a way that permits their use in tracing the origin and migration of different groups of people.

Hundreds of variants of hemoglobin have been identified by electrophoresis, but relatively few are frequent enough to be called polymorphisms. Of the polymorphisms, the alleles for sickle-cell and thalassemia hemoglobins produce serious disease in homozygotes, whereas others (hemoglobins C, D, and E) do not. The sickle-cell polymorphism confers a selective advantage on the heterozygote living in a malarial environment; the thalassemia polymorphism provides a similar advantage.

Read more:

Human genetics | biology |

SASHG Southern African Society for Human Genetics (SASHG)

The Society is open for membership to any person interested in the field of Human Genetics irrespective of that persons specific discipline. Thus medical practitioners, nursing practitioners, scientists, social workers en technologists are all welcome to be members.Because the Society does not want to limit itself to South Africa but is interested in developing Human Genetics in Southern Africa, membership is not limited geographically either.

See the original post:

SASHG Southern African Society for Human Genetics (SASHG)

Basic Genetics

Learn.Genetics visitors,

Were asking for your help. For over 20 years, the Learn.Genetics website has provided engaging, multimedia educational materials at no cost.

Learn.Genetics is one of the most-used science websites. Tens of millions of visitors come to our site each year to find the science and health information theyre looking for.

If Learn.Genetics is useful to you, please take a moment to donate even a few dollars from each of our visitors would add up to a significant amount!

Your support will help us keep Learn.Genetics free and available to everyone. It will also help us develop new content for you.

Please help us keep Learn.Genetics going!

Thank you, The Genetic Science Learning Center team creators of Learn.Genetics

Continue reading here:

Basic Genetics

Nanoengineering – Wikipedia

Nanoengineering is the practice of engineering on the nanoscale. It derives its name from the nanometre, a unit of measurement equalling one billionth of a meter.

Nanoengineering is largely a synonym for nanotechnology, but emphasizes the engineering rather than the pure science aspects of the field.

The first nanoengineering program was started at the University of Toronto within the Engineering Science program as one of the options of study in the final years. In 2003, the Lund Institute of Technology started a program in Nanoengineering. In 2004, the College of Nanoscale Science and Engineering at SUNY Polytechnic Institute was established on the campus of the University at Albany. In 2005, the University of Waterloo established a unique program which offers a full degree in Nanotechnology Engineering. [1] Louisiana Tech University started the first program in the U.S. in 2005. In 2006 the University of Duisburg-Essen started a Bachelor and a Master program NanoEngineering. [2] Unlike early NanoEngineering programs, the first Nanoengineering Department in the world, offering both undergraduate and graduate degrees, was established by the University of California, San Diego in 2007.In 2009, the University of Toronto began offering all Options of study in Engineering Science as degrees, bringing the second nanoengineering degree to Canada. Rice University established in 2016 a Department of Materials Science and NanoEngineering (MSNE).DTU Nanotech – the Department of Micro- and Nanotechnology – is a department at the Technical University of Denmark established in 1990.

In 2013, Wayne State University began offering a Nanoengineering Undergraduate Certificate Program, which is funded by a Nanoengineering Undergraduate Education (NUE) grant from the National Science Foundation. The primary goal is to offer specialized undergraduate training in nanotechnology. Other goals are: 1) to teach emerging technologies at the undergraduate level, 2) to train a new adaptive workforce, and 3) to retrain working engineers and professionals.[3]

Go here to read the rest:

Nanoengineering – Wikipedia

Undergraduate Degree Programs | NanoEngineering

The Department of NanoEngineering offers undergraduate programs leading to theB.S. degreesinNanoengineeringandChemical Engineering. The Chemical Engineering and NanoEngineering undergraduate programs areaccredited by the Engineering Accreditation Commission of ABET. The undergraduate degree programs focus on integrating the various sciences and engineering disciplines necessary for successful careers in the evolving nanotechnology industry.These two degree programshave very different requirements and are described in separate sections.

B.S. NanoEngineering

TheNanoEngineering Undergraduate Program became effective Fall 2010.Thismajor focuses on nanoscale science, engineering, and technology that have the potential to make valuable advances in different areas that include, to name a few, new materials, biology and medicine, energy conversion, sensors, and environmental remediation. The program includes affiliated faculty from the Department of NanoEngineering, Department of Mechanical and Aerospace Engineering, Department of Chemistry and Biochemistry, and the Department of Bioengineering. The NanoEngineering undergraduate program is tailored to provide breadth and flexibility by taking advantage of the strength of basic sciences and other engineering disciplines at UC San Diego. The intention is to graduate nanoengineers who are multidisciplinary and can work in a broad spectrum of industries.

B.S. Chemical Engineering

The Chemical Engineering undergraduate program is housed within the NanoEngineering Department. The program is made up of faculty from the Department of Mechanical and Aerospace Engineering, Department of Chemistry and Biochemistry, the Department of Bioengineering and the Department of NanoEngineering. The curricula at both the undergraduate and graduate levels are designed to support and foster chemical engineering as a profession that interfaces engineering and all aspects of basic sciences (physics, chemistry, and biology). As of Fall 2008, the Department of NanoEngineering has taken over the administration of the B.S. degree in Chemical Engineering.

Academic Advising

Upon admission to the major, students should consult the catalog or NanoEngineering website for their program of study, and their undergraduate/graduate advisor if they have questions. Because some course and/or curricular changes may be made every year, it is imperative that students consult with the departments student affairs advisors on an annual basis.

Students can meet with the academic advisors during walk-in hours, schedule an appointment, or send messages through the Virtual Advising Center (VAC).

Program Alterations/Exceptions to Requirements

Variations from or exceptions to any program or course requirements are possible only if the Undergraduate Affairs Committee approves a petition before the courses in question are taken.

Independent Study

Students may take NANO 199 or CENG 199, Independent Study for Undergraduates, under the guidance of a NANO or CENG faculty member. This course is taken as an elective on a P/NP basis. Under very restrictive conditions, however, it may be used to satisfy upper-division Technical Elective or Nanoengineering Elective course requirements for the major. Students interested in this alternative must have completed at least 90 units and earned a UCSD cumulative GPA of 3.0 or better. Eligible students must identify a faculty member with whom they wish to work and propose a two-quarter research or study topic. Please visit the Student Affairs office for more information.

Go here to see the original:

Undergraduate Degree Programs | NanoEngineering

UC San Diego NanoEngineering Department

The NanoEngineering program has received accreditation by the Accreditation Commission of ABET, the global accreditor of college and university programs in applied and natural science, computing, engineering and engineering technology. UC San Diego’s NanoEngineering program is the first of its kind in the nation to receive this accreditation. Our NanoEngineering students can feel confident that their education meets global standards and that they will be prepared to enter the workforce worldwide.

ABET accreditation assures that programs meet standards to produce graduates ready to enter critical technical fields that are leading the way in innovation and emerging technologies, and anticipating the welfare and safety needs of the public. Please visit the ABET website for more information on why accreditation matters.

Congratulations to the NanoEngineering department and students!

The rest is here:

UC San Diego NanoEngineering Department


Turning the NaI concept into reality necessitates an extraordinary and long-term effort. This requires the integration of nanoelectronics, nanophotonics, nanophononics, nanospintronics, topological effects, as well as the physics and chemistry of materials. This also requires operations in an extremely broad range of science and technology, including Microwaves, Millimeter waves, TeraHertz, Infrared and Optics, and will exploit various excitations, such as surface waves, spin waves, phonons, electrons, photons, plasmons, and their hybrids, for sensing, information processing and storage. Integrating

This high level of integration, which goes beyond individual functionalities, components and devices and requires cooperation across a range of disciplines, makes the Nano Engineering Flagship unique in its approach. It will be crucial in tackling the 6 strategic challenges identified as:

Here is the original post:



Nano-Engineering introduces a novel key-enabling non-invasive broadband technology, the Nano-engineered Interface (NaI), realising omni -connectivity and putting humans and their interactions at the center of the future digital society.Omni-connectivity encompasses real-time communication, sensing, monitoring, and data processing among humans, objects, and their environment. The vision of Omni-connectivity englobes people in a new sphere of extremely simplified, intuitive and natural communication.The Nano-engineered Interface (NaI) a non-invasive wireless ultraflat functional system will make this possible. NaI will be applicable to any surface on any physical item and thereby exponentially diversify and increase connections among humans, wearables, vehicles, and everyday objects. NaI will communicate with other NaI-networks from local up to satellites by using the whole frequency spectrum from microwave frequency to optics

Go here to read the rest:


NETS – What are Nanoengineering and Nanotechnology?

is one billionth of a meter, or three to five atoms in width. It would take approximately 40,000 nanometers lined up in a row to equal the width of a human hair. NanoEngineering concerns itself with manipulating processes that occur on the scale of 1-100 nanometers.

The general term, nanotechnology, is sometimes used to refer to common products that have improved properties due to being fortified with nanoscale materials. One example is nano-improved tooth-colored enamel, as used by dentists for fillings. The general use of the term nanotechnology then differs from the more specific sciences that fall under its heading.

NanoEngineering is an interdisciplinary science that builds biochemical structures smaller than bacterium, which function like microscopic factories. This is possible by utilizing basic biochemical processes at the atomic or molecular level. In simple terms, molecules interact through natural processes, and NanoEngineering takes advantage of those processes by direct manipulation.


See the rest here:

NETS – What are Nanoengineering and Nanotechnology?

Human Genetics – McGraw-Hill Education


C H A P T E R 1

What Is in a Human Genome?

C H A P T E R 2


C H A P T E R 3

Meiosis, Development, and Aging

P A R T 2

Transmission Genetics

C H A P T E R 4

Single-Gene Inheritance

C H A P T E R 5

Beyond Mendels Laws

C H A P T E R 6

Matters of Sex

C H A P T E R 7

Multifactorial Traits

C H A P T E R 8

Genetics of Behavior

P A R T 3

DNA and Chromosomes

C H A P T E R 9

DNA Structure and Replication

C H A P T E R 10

Gene Action: From DNA to Protein

C H A P T E R 11

Gene Expression and Epigenetics

C H A P T E R 12

Gene Mutation

C H A P T E R 13


P A R T 4

Population Genetics

C H A P T E R 14

Constant Allele Frequencies and DNA Forensics

C H A P T E R 15

Changing Allele Frequencies

C H A P T E R 16

Human Ancestry and Evolution

P A R T 5

Immunity and Cancer

C H A P T E R 17

Genetics of Immunity

C H A P T E R 18

Cancer Genetics and Genomics

P A R T 6

Genetic Technology

C H A P T E R 19

DNA Technologies

C H A P T E R 20

Genetic Testing and Treatment

C H A P T E R 21

Reproductive Technologies

C H A P T E R 22


Read more here:

Human Genetics – McGraw-Hill Education

Human genetic disease |

About 1 out of 150 live newborns has a detectable chromosomal abnormality. Yet even this high incidence represents only a small fraction of chromosome mutations since the vast majority are lethal and result in prenatal death or stillbirth. Indeed, 50 percent of all first-trimester miscarriages and 20 percent of all second-trimester miscarriages are estimated to involve a chromosomally abnormal fetus.

Chromosome disorders can be grouped into three principal categories: (1) those that involve numerical abnormalities of the autosomes, (2) those that involve structural abnormalities of the autosomes, and (3) those that involve the sex chromosomes. Autosomes are the 22 sets of chromosomes found in all normal human cells. They are referred to numerically (e.g., chromosome 1, chromosome 2) according to a traditional sort order based on size, shape, and other properties. Sex chromosomes make up the 23rd pair of chromosomes in all normal human cells and come in two forms, termed X and Y. In humans and many other animals, it is the constitution of sex chromosomes that determines the sex of the individual, such that XX results in a female and XY results in a male.

Numerical abnormalities, involving either the autosomes or sex chromosomes, are believed generally to result from meiotic nondisjunctionthat is, the unequal division of chromosomes between daughter cellsthat can occur during either maternal or paternal gamete formation. Meiotic nondisjunction leads to eggs or sperm with additional or missing chromosomes. Although the biochemical basis of numerical chromosome abnormalities remains unknown, maternal age clearly has an effect, such that older women are at significantly increased risk to conceive and give birth to a chromosomally abnormal child. The risk increases with age in an almost exponential manner, especially after age 35, so that a pregnant woman age 45 or older has between a 1 in 20 and 1 in 50 chance that her child will have trisomy 21 (Down syndrome), while the risk is only 1 in 400 for a 35-year-old woman and less than 1 in 1,000 for a woman under the age of 30. There is no clear effect of paternal age on numerical chromosome abnormalities.

Although Down syndrome is probably the best-known and most commonly observed of the autosomal trisomies, being found in about 1 out of 800 live births, both trisomy 13 and trisomy 18 are also seen in the population, albeit at greatly reduced rates (1 out of 10,000 live births and 1 out of 6,000 live births, respectively). The vast majority of conceptions involving trisomy for any of these three autosomes are nonetheless lost to miscarriage, as are all conceptions involving trisomy for any of the other autosomes. Similarly, monosomy for any of the autosomes is lethal in utero and therefore is not seen in the population. Because numerical chromosomal abnormalities generally result from independent meiotic events, parents who have one pregnancy with a numerical chromosomal abnormality are generally not at markedly increased risk above the general population to repeat the experience. Nonetheless, a small increased risk is generally cited for these couples to account for unusual situations, such as chromosomal translocations or gonadal mosaicism, described below.

Structural abnormalities of the autosomes are even more common in the population than are numerical abnormalities and include translocations of large pieces of chromosomes, as well as smaller deletions, insertions, or rearrangements. Indeed, about 5 percent of all cases of Down syndrome result not from classic trisomy 21 but from the presence of excess chromosome 21 material attached to the end of another chromosome as the result of a translocation event. If balanced, structural chromosomal abnormalities may be compatible with a normal phenotype, although unbalanced chromosome structural abnormalities can be every bit as devastating as numerical abnormalities. Furthermore, because many structural defects are inherited from a parent who is a balanced carrier, couples who have one pregnancy with a structural chromosomal abnormality generally are at significantly increased risk above the general population to repeat the experience. Clearly, the likelihood of a recurrence would depend on whether a balanced form of the structural defect occurs in one of the parents.

Even a small deletion or addition of autosomal materialtoo small to be seen by normal karyotyping methodscan produce serious malformations and mental retardation. One example is cri du chat (French: cry of the cat) syndrome, which is associated with the loss of a small segment of the short arm of chromosome 5. Newborns with this disorder have a mewing cry like that of a cat. Mental retardation is usually severe.

About 1 in 400 male and 1 in 650 female live births demonstrate some form of sex chromosome abnormality, although the symptoms of these conditions are generally much less severe than are those associated with autosomal abnormalities. Turner syndrome is a condition of females who, in the classic form, carry only a single X chromosome (45,X). Turner syndrome is characterized by a collection of symptoms, including short stature, webbed neck, and incomplete or absent development of secondary sex characteristics, leading to infertility. Although Turner syndrome is seen in about 1 in 2,500 to 1 in 5,000 female live births, the 45,X karyotype accounts for 10 to 20 percent of the chromosomal abnormalities seen in spontaneously aborted fetuses, demonstrating that almost all 45,X conceptions are lost to miscarriage. Indeed, the majority of liveborn females with Turner syndrome are diagnosed as mosaics, meaning that some proportion of their cells are 45,X while the rest are either 46,XX or 46,XY. The degree of clinical severity generally correlates inversely with the degree of mosaicism, so that females with a higher proportion of normal cells will tend to have a milder clinical outcome.

In contrast to Turner syndrome, which results from the absence of a sex chromosome, three alternative conditions result from the presence of an extra sex chromosome: Klinefelter syndrome, trisomy X, and 47,XYY syndrome. These conditions, each of which occurs in about 1 in 1,000 live births, are clinically mild, perhaps reflecting the fact that the Y chromosome carries relatively few genes, and, although the X chromosome is gene-rich, most of these genes become transcriptionally silent in all but one X chromosome in each somatic cell (i.e., all cells except eggs and sperm) via a process called X inactivation. The phenomenon of X inactivation prevents a female who carries two copies of the X chromosome in every cell from expressing twice the amount of gene products encoded exclusively on the X chromosome, in comparison with males, who carry a single X. In brief, at some point in early development one X chromosome in each somatic cell of a female embryo undergoes chemical modification and is inactivated so that gene expression no longer occurs from that template. This process is apparently random in most embryonic tissues, so that roughly half of the cells in each somatic tissue will inactivate the maternal X while the other half will inactivate the paternal X. Cells destined to give rise to eggs do not undergo X inactivation, and cells of the extra-embryonic tissues preferentially inactivate the paternal X, although the rationale for this preference is unclear. The inactivated X chromosome typically replicates later than other chromosomes, and it physically condenses to form a Barr body, a small structure found at the rim of the nucleus in female somatic cells between divisions (see photograph). The discovery of X inactivation is generally attributed to British geneticist Mary Lyon, and it is therefore often called lyonization.

The result of X inactivation is that all normal females are mosaics with regard to this chromosome, meaning that they are composed of some cells that express genes only from the maternal X chromosome and others that express genes only from the paternal X chromosome. Although the process is apparently random, not every female has an exact 1:1 ratio of maternal to paternal X inactivation. Indeed, studies suggest that ratios of X inactivation can vary. Furthermore, not all genes on the X chromosome are inactivated; a small number escape modification and remain actively expressed from both X chromosomes in the cell. Although this class of genes has not yet been fully characterized, aberrant expression of these genes has been raised as one possible explanation for the phenotypic abnormalities experienced by individuals with too few or too many X chromosomes.

Klinefelter syndrome (47,XXY) occurs in males and is associated with increased stature and infertility. Gynecomastia (i.e., partial breast development in a male) is sometimes also seen. Males with Klinefelter syndrome, like normal females, inactivate one of their two X chromosomes in each cell, perhaps explaining, at least in part, the relatively mild clinical outcome.

Trisomy X (47,XXX) is seen in females and is generally also considered clinically benign, although menstrual irregularities or sterility have been noted in some cases. Females with trisomy X inactivate two of the three X chromosomes in each of their cells, again perhaps explaining the clinically benign outcome.

47,XYY syndrome also occurs in males and is associated with tall stature but few, if any, other clinical manifestations. There is some evidence of mild learning disability associated with each of the sex chromosome trisomies, although there is no evidence of mental retardation in these persons.

Persons with karyotypes of 48,XXXY or 49,XXXXY have been reported but are extremely rare. These individuals show clinical outcomes similar to those seen in males with Klinefelter syndrome but with slightly increased severity. In these persons the n 1 rule for X inactivation still holds, so that all but one of the X chromosomes present in each somatic cell is inactivated.

See original here:

Human genetic disease |

Heredity: Crash Course Biology #9

Hank and his brother John discuss heredity via the gross example of relative ear wax moistness.

Crash Course Biology is now available on DVD!…

Like CrashCourse on Facebook!…Follow CrashCourse on Twitter!

This video uses sounds from, a list of which can be found, along with the REFERENCES for this episode, in the Google document here:

tags: crashcourse, science, biology, evolution, genetics, heredity, aristotle, bloodlines, gregor mendel, mendelian genetics, mendelian trait, classical genetics, chromosome, gene, polygenic, pleiotropic, allele, ear wax gene, somatic, diploid, gametes, sperm, egg, haploid, polyploid, dominance, dominant, recessive, heterozygous, homozygous, phenotype, punnett square, reginald c. punnett, sex-linked inheritance, autosome Support CrashCourse on Subbable:

Excerpt from:

Heredity: Crash Course Biology #9

Division of Human Genetics


Clinical genetics focuses on providing comprehensive diagnostic, management and treatment services with emphasis on tailoring care to specific patient and family needs, through interdisciplinary clinics and programs.

Clinical laboratory services develop and implement state-of-the-art technologies for biochemical, cytogenetic, and molecular diagnostic testing for a multitude of pediatric and adult disorders.

Ourresearch focuses on basic disease mechanisms with translational import and improved outcomes for gene influenced diseases.

The Division of Human Genetics is a leader in genetics education. The Genetic Counseling Graduate Program is one of the oldest and largest such programs in the United States.We have American Board of Medical Genetics-certified training programs in medical genetics, medical and clinical biochemical genetics and Laboratory for Genetics and Genomics (LGG) for training leaders in human genetics.

Division director Louis J. Muglia, MD, PhD, explains the vision for Human Genetics at Cincinnati Childrens.

More here:

Division of Human Genetics

Scientists Say New Material Could Hold up an Actual Space Elevator

Space Elevator

It takes a lot of energy to put stuff in space. That’s why one longtime futurist dream is a “space elevator” — a long cable strung between a geostationary satellite and the Earth that astronauts could use like a dumbwaiter to haul stuff up into orbit.

The problem is that such a system would require an extraordinarily light, strong cable. Now, researchers from Beijing’s Tsinghua University say they’ve developed a carbon nanotube fiber so sturdy and lightweight that it could be used to build an actual space elevator.

Going Up

The researchers published their paper in May, but it’s now garnering the attention of their peers. Some believe the Tsinghua team’s material really could lead to the creation of an elevator that would make it cheaper to move astronauts and materials into space.

“This is a breakthrough,” colleague Wang Changqing, who studies space elevators at Northwestern Polytechnical University, told the South China Morning Post.

Huge If True

There are still countless galling technical problems that need to be overcome before a space elevator would start to look plausible. Wang pointed out that it’d require tens of thousands of kilometers of the new material, for instance, as well as a shield to protect it from space debris.

But the research brings us one step closer to what could be a true game changer: a vastly less expensive way to move people and spacecraft out of Earth’s gravity.

READ MORE: China Has Strongest Fibre That Can Haul 160 Elephants – and a Space Elevator? [South China Morning Post]

More on space elevators: Why Space Elevators Could Be the Future of Space Travel

See the original post here:

Scientists Say New Material Could Hold up an Actual Space Elevator

AI Dreamed Up These Nightmare Fuel Halloween Masks

Nightmare Fuel

Someone programmed an AI to dream up Halloween masks, and the results are absolute nightmare fuel. Seriously, just look at some of these things.

“What’s so scary or unsettling about it is that it’s not so detailed that it shows you everything,” said Matt Reed, the creator of the masks, in an interview with New Scientist. “It leaves just enough open for your imagination to connect the dots.”

A selection of masks featured on Reed’s twitter. Credit: Matt Reed/Twitter

Creative Horror

To create the masks, Reed — whose day job is as a technologist at a creative agency called redpepper — fed an open source AI tool 5,000 pictures of Halloween masks he sourced from Google Images. He then instructed the tool to generate its own masks.

The fun and spooky project is yet another sign that AI is coming into its own as a creative tool. Just yesterday, a portrait generated by a similar system fetched more than $400,000 at a prominent British auction house.

And Reed’s masks are evocative. Here at the Byte, if we looked through the peephole and saw one of these on a trick or treater, we might not open our door.

READ MORE: AI Designed These Halloween Masks and They Are Absolutely Terrifying [New Scientist]

More on AI-generated art: Generated Art Will Go on Sale Alongside Human-Made Works This Fall

More here:

AI Dreamed Up These Nightmare Fuel Halloween Masks

Robot Security Guards Will Constantly Nag Spectators at the Tokyo Olympics

Over and Over

“The security robot is patrolling. Ding-ding. Ding-ding. The security robot is patrolling. Ding-ding. Ding-ding.”

That’s what Olympic attendees will hear ad nauseam when they step onto the platforms of Tokyo’s train stations in 2020. The source: Perseusbot, a robot security guard Japanese developers unveiled to the press on Thursday.

Observe and Report

According to reporting by Kyodo News, the purpose of the AI-powered Perseusbot is to lower the burden on the stations’ staff when visitors flood Tokyo during the 2020 Olympics.

The robot is roughly 5.5 feet tall and equipped with security cameras that allow it to note suspicious behaviors, such as signs of violence breaking out or unattended packages, as it autonomous patrols the area. It can then alert security staff to the issues by sending notifications directly to their smart phones.

Prior Prepration

Just like the athletes who will head to Tokyo in 2020, Perseusbot already has a training program in the works — it’ll patrol Tokyo’s Seibu Shinjuku Station from November 26 to 30. This dry run should give the bot’s developers a chance to work out any kinks before 2020.

If all goes as hoped, the bot will be ready to annoy attendees with its incessant chant before the Olympic torch is lit. And, you know, keep everyone safe, too.

READ MORE: Robot Station Security Guard Unveiled Ahead of 2020 Tokyo Olympics [Kyodo News]

More robot security guards: Robot Security Guards Are Just the Beginning

See the rest here:

Robot Security Guards Will Constantly Nag Spectators at the Tokyo Olympics

People Would Rather a Self-Driving Car Kill a Criminal Than a Dog

Snap Decisions

On first glance, a site that collects people’s opinions about whose life an autonomous car should favor doesn’t tell us anything we didn’t already know. But look closer, and you’ll catch a glimpse of humanity’s dark side.

The Moral Machine is an online survey designed by MIT researchers to gauge how the public would want an autonomous car to behave in a scenario in which someone has to die. It asks questions like: “If an autonomous car has to choose between killing a man or a woman, who should it kill? What if the woman is elderly but the man is young?”

Essentially, it’s a 21st century update on the Trolley Problem, an ethical thought experiment no doubt permanently etched into the mind of anyone who’s seen the second season of “The Good Place.”

Ethical Dilemma

The MIT team launched the Moral Machine in 2016, and more than two million people from 233 countries participated in the survey — quite a significant sample size.

On Wednesday, the researchers published the results of the experiment in the journal Nature, and they really aren’t all that surprising: Respondents value the life of a baby over all others, with a female child, male child, and pregnant woman following closely behind. Yawn.

It’s when you look at the other end of the spectrum — the characters survey respondents were least likely to “save” — that you’ll see something startling: Survey respondents would rather the autonomous car kill a human criminal than a dog.

moral machine
Image Credit: MIT

Ugly Reflection

While the team designed the survey to help shape the future of autonomous vehicles, it’s hard not to focus on this troubling valuing of a dog’s life over that of any human, criminal or not. Does this tell us something important about how society views the criminal class? Reveal that we’re all monsters when hidden behind the internet’s cloak of anonymity? Confirm that we really like dogs?

The MIT team doesn’t address any of these questions in their paper, and really, we wouldn’t expect them to — it’s their job to report the survey results, not extrapolate some deeper meaning from them. But whether the Moral Machine informs the future of autonomous vehicles or not, it’s certainly held up a mirror to humanity’s values, and we do not like the reflection we see.

READ MORE: Driverless Cars Should Spare Young People Over Old in Unavoidable Accidents, Massive Survey Finds [Motherboard]

More on the Moral Machine: MIT’s “Moral Machine” Lets You Decide Who Lives & Dies in Self-Driving Car Crashes

See the original post here:

People Would Rather a Self-Driving Car Kill a Criminal Than a Dog

You Can Now Preorder a $150,000 Hoverbike

Please, Santa?

It’s never too early to start writing your Christmas wish list, right? Because we know what’s now at the top of ours: a hoverbike.

We’ve had our eyes on Hoversurf’s Scorpion-3 since early last year — but now, the Russian drone start-up is accepting preorders on an updated version of the vehicle.

Flying Bike

The S3 2019 is part motorcycle and part quadcopter. According to the Hoversurf website, the battery-powered vehicle weighs 253 pounds and has a flight time of 10 to 25 minutes depending on operator weight. Its maximum legal speed is 60 mph — though as for how fast the craft can actually move, that’s unknown. Hoversurf also notes that the vehicle’s “safe flight altitude” is 16 feet, but again, we aren’t sure how high it can actually soar.

What we do know: The four blades that provide S3 with its lift spin at shin level, and while this certainly looks like it would be a safety hazard, the U.S. Department of Transportation’s Federal Aviation Administration approved the craft for legal use as an ultralight vehicle in September.

That means you can only operate an S3 for recreational or sports purposes — but you can’t cruise to work on your morning commute.

Plummeting Bank Account

You don’t need a pilot’s license to operate an S3, but you will need a decent amount of disposable income — the Star Wars-esque craft will set you back $150,000.

If that number doesn’t cause your eyes to cross, go ahead and slap down the $10,000 deposit needed to claim a spot in the reservation queue. You’ll then receive an email when it’s time to to place your order. You can expect to receive your S3 2019 two to six months after that, according to the company website.

That means there’s a pretty good chance you won’t be able to hover around your front yard this Christmas morning, but a 2019 jaunt is a genuine possibility.

READ MORE: For $150,000 You Can Now Order Your Own Hoverbike [New Atlas]

More on Hoversurf: Watch the World’s First Rideable Hoverbike in Flight

Original post:

You Can Now Preorder a $150,000 Hoverbike