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The convoluted history of sex determination in sport
Published in Cheryl Mallen, Emerging Technologies in Sport, 2019
Ian Ritchie, Lindsay Parks Pieper
In some ways the IOC went in the opposite direction of the IAAF, at least temporarily. Its Medical Commission met in 1991 and embraced a new technology called polymerase chain reaction (PCR). PCR testing identifies the presence of SRY gene by amplifying DNA sequences. The SRY gene starts the production of testosterone and is usually, but not always, linked to the development of male genitalia. Although the IOC Medical Commission believed this technique was more accurate than the Barr body test, medical practitioners pointed out the problem with focusing on one single identifier to determine sex and also warned about the likelihood of false positives with PCR testing.32 Nonetheless, the IOC applied this technology during the four Olympic Games held in the 1990s. However, when the IOC Athletes’ Commission wrote a statement condemning the practice, citing medical and scientific authorities including de la Chapelle, the IOC decided to finally give up on mandatory testing. The 2000 Summer Games in Sydney, Australia, was the first Olympics in decades during which female athletes were not required to undergo the test.
Glossary of scientific and technical terms in bioengineering and biological engineering
Published in Megh R. Goyal, Scientific and Technical Terms in Bioengineering and Biological Engineering, 2018
Y-chromosome is one of two sex chromosomes (allosomes) in mammals, including humans, and many other animals. The other is the X chromosome. Y is the sex-determining chromosome in many species, since it is the presence or absence of Y that determines male or female sex. In mammals, the Y chromosome contains the gene SRY, which triggers testis development. The DNA in the human Y chromosome is composed of about 59 million base pairs. The Y chromosome is passed only from father to son, so analysis of Y chromosome DNA may thus be used in genealogical research. With a 30% difference between humans and chimpanzees, the Y chromosome is one of the fastest evolving parts of the human genome. To date, over 200 Y-linked genes have been identified. All Y-linked genes are expressed and (apart from duplicated genes) hemizygous (present on only one chromosome) except in the cases of aneuploidy such as Klinefelter’s Syndrome (47,XXY) or XXYY syndrome.
Naturally Occurring Polymers—Animals
Published in Charles E. Carraher, Carraher's Polymer Chemistry, 2017
We have just considered mitosis in general. We can take a simplistic look at the determination of whether a given embryo is a male or female. Females have two X chromosomes while males have one X and one Y so that the ability of the X chromosome to overwhelm the Y chromosomes and give only female embryos is favored on a statistical basis. On a size basis, the Y chromosome is the smallest of all the chromosomes while the X is among the largest. Further, the Y chromosome is largely composed of noncoding DNA, giving few targets for the X chromosome to interact with. The gene on the Y chromosome that makes men is called the SRY gene. The SRY gene interacts with the DAX gene on the X chromosome. In some sense, these two genes are antagonistic to one another where two DAX genes overcome the single SRY gene but one SRY gene overcomes one DAX gene so that depending on the particular course of events, the outcome is a male or female. The SRY gene, when activated, ignites a whole cascade of events that leads to the maculation of the embryo. The SKY gene is peculiar in that it is remarkably consistent between men with essentially no variations in the coding regardless of race. Further, the human SRY gene is very different from those of other primates.
Teleology and Defining Sex
Published in The New Bioethics, 2018
Nathan K. Gamble, Michal Pruski
It is apparent that even this overly simplified presentation of the sexual differentiation mechanism is complex. Errors can occur at any stage of development. If the androgen receptor is functionally absent throughout the body, the individual may as well be producing no androgens (Barrett et al. 2010). It is analogous to phoning someone who does not have a phone. The TDF gene may be missing or damaged – that is, TDF cannot initiate the cascade (Gottlieb et al. 1993). A normal XY embryo might fuse with an XX embryo, resulting in a chimeric child with a percentage of normal XY cells and a percentage of normal XX cells (Jager et al. 1990). The SRY gene may translocate (move) to an X chromosome in a gamete so that the child has two XX chromosomes but can code for the protein that initiates the gene cascade for a male phenotype (Strain et al. 1998).
Developing gene drive technologies to eradicate invasive rodents from islands
Published in Journal of Responsible Innovation, 2018
Caroline M. Leitschuh, Dona Kanavy, Gregory A. Backus, Rene X. Valdez, Megan Serr, Elizabeth A. Pitts, David Threadgill, John Godwin
Gene editing tools are being used at Texas A&M University to create ‘daughterless’ mice – in other words, mice that are unable to bear female offspring – by inserting the Sry gene sequence into the t-haplotype. The Sry gene is normally located on the Y-chromosome and controls the development of male characteristics. Because the t-haplotype has meiotic drive and is located on an autosome, in order to spread the Sry gene to both XX and XY offspring, the Sry gene has to be copied and inserted into the t-haplotype. This ensures that all offspring receiving the t-allele with the Sry gene, regardless of chromosomal sex, would be phenotypically male (Figure 1; Piaggio et al. 2017). Targeting a construct containing Sry to the t-haplotype should result in nearly all offspring inheriting the Sry gene. Releasing male genetically engineered (GE) mice with the Sry/t-haplotype into a population of wild mice, where they could breed with wild females, could be effective in spreading the Sry/t-haplotype through a population and increasing the relative proportion of male mice in a population.