Tag Info

New answers tagged

2

Your answer to your titular question, How was the origin of CTVT parasitic cancer determined? is that cytogenic studies were done on the tumors. It arose in dogs and was logically assumed to be of dog origin, and was first characterized in 1876. The tumor cells were/are characterized by a rearranged karyotype, which is similar in tumors from in different ...


3

The reason is that X-inactivation is not complete (Carrell & Willard, 2005; Ahn & Lee, 2008), and as many as 15-25% of X-linked genes escape silencing (Carrell & Willard, 2005; Cheng et al, 2005). This means that some genes on the Barr body are expressed in XX-females, although often at lower levels compared to the active X-chromosome, and this ...


0

Very interesting question! And I don't think either that the linked Wikipedia article answers the question. Unfortunately I do not know the answer for sure, but I might have some relevant information to add. So, from my studies I know that Barr-bodies are not totally inactive, they, in fact, do have some very limited transcriptional activity. It might be ...


4

I'm not sure about the ubiquity of this but, in many animals, each each primary oocyte that undergoes oogenesis only produces one mature egg. The other products of meiosis are polar bodies, which are not fertilised. These cells often degenerate but can sometimes play supportive roles in embryogenesis. To answer your question, each mature egg is ...


3

While your question asking about birds, reptiles and fish (oh my!) may be too broad, hopefully looking at frog oogenesis can show some differences in large offspring number v. small offspring number. Some frogs even give birth to live offspring (Iskandar et al. 2014). Much of this explanation can be found in Developmental Biology, 6th edition by Gilbert ...


1

If one looks at the sequence map in detail, at the fusion point we find both telomere and pre-telomere sequences. And what is particularly compelling, is that these main groups occur in the correct order. That is, first you see a pre-telomere sequence, then a telomere sequence. Then we see the telomeres inverted and the inverted pre-telomeres after that. ...



Top 50 recent answers are included