* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download No Slide Title
Ridge (biology) wikipedia , lookup
Biology and sexual orientation wikipedia , lookup
Genomic imprinting wikipedia , lookup
Gene expression programming wikipedia , lookup
Genome evolution wikipedia , lookup
Sexual dimorphism wikipedia , lookup
Y chromosome wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
History of genetic engineering wikipedia , lookup
Point mutation wikipedia , lookup
Epigenetics of human development wikipedia , lookup
X-inactivation wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Biology and consumer behaviour wikipedia , lookup
Designer baby wikipedia , lookup
Gene expression profiling wikipedia , lookup
Cell-free fetal DNA wikipedia , lookup
Microevolution wikipedia , lookup
Human sex determination: The supremacy of the Y Genetic analyses established the Y as “testisdetermining” – XO = female – XXY = male Gonadal sex determination – early fetal “indifferent” gonad – determination as testis or ovary – expt’l evidence for subsequent role of hormones (esp. testosterone and Mullerian inhibiting hormone, MIS) Review: The search for “TDF” (SRY) Experimental paradigm: sex-reversed individuals – XY females (missing critical bit of Y) – XX males (possessing critical bit of Y) Deletion mapping of Y coupled with analysis of sex-reversed individuals and “chromosome walking” to get new sequences The pivotal male sex-determining gene: SRY Sequencing revealed a conserved motif that could have DNA-binding function SRY = TDF – XY sex-reversed females have deletions or mutations of SRY – transgenic mouse model - XX + Sry leads to testis development – SRY expressed in gonad, but only transiently, at the onset of differentiation Downstream sex-determining genes Puzzling XY sex-reversed females without detectable mutation in SRY provide evidence for additional genes, including: – DAX1 - on X, can suppress testis-formation in a dosage-sensitive manner – SOX9 - on 17q, required with SRY for normal testis formation Other genes influence sexual differentiation X-linked androgen insensitivity identified the androgen receptor gene Deficiency for 5a-reductase leads to failure to convert T to active form, DHT, and subsequent feminization of external genitalia in affected males Congenital adrenal hyperplasia, e.g., deficiency of 21-hydroxylase, leads to excess androgen and masculinization of female genitalia