Therian mammals possess an XY sex-determination system, where females have a pair of X chromosomes, and males harbor one X and one Y chromosome. However, the sex-determination system of platypus stands in stark contrast: the female has five different pairs of X chromosomes, while males have five X chromosomes and five Y chromosomes.
In a study carried out at the Australian National University in Canberra, scientists used physical mapping of chromosomes to investigate homology and the evolutionary relationships between platypus and therian sex chromosomes.
“Surprisingly, we find that the platypus sex chromosomes are unrelated to the X or Y chromosomes of other mammals, and lack the mammalian sex determining gene SRY and the gene from which it evolved,” explains co-first author Dr. Paul Waters. “Instead, their sex chromosomes share extensive homology to those of birds.” Waters notes that this finding suggests our ancient mammal-like reptile ancestor may have had bird-like sex chromosomes and sex determination system.-Cold Spring Harbor Laboratory
Comment and add to the story without registration, but keep the comments meaningful please. Links are not accepted.
