The Possibility of Pentasomy?

[Captain Covalency]

So, we know of Monosomy and Trisomy, caused either by the nondisjuction of duplicated homologous chromosomes in Anaphase I, or by nondisjuction of the sister chromatids in Anaphase II. However, in both cases, we assume that the error occurs solely in Anaphase I OR Anaphase II. Now, although it would be extremely rare for two nondisjuctions to occur the the exact same genome sector (i.e. A chromosome of pair 21), what would occur if it did? Technically, if nondisjuction occurred to the same genome sector in both Anaphase I and II, then a Pentasomy would occur, in which out of the four potential gametes that would have been produced, one has five homologous chromosomes (Of the specific genome sector in which the nondosjuctions occured), and the rest would have monosomies in that given genome sector. Given that many organisms die in their fetal stages with just simple monosomies and trisomies, I would assume a pentasomy would result in a quick miscarriage after fertilization? What do you think of this possible error of meiosis?

 

[origin]

Given that many organisms die in their fetal stages with just simple monosomies and trisomies, I would assume a pentasomy would result in a quick miscarriage after fertilization? What do you think of this possible error of meiosis?

I would agree that the most likely outcome would be a miscarrage considering the exceedingly rare instances of pentasomy X.

 

[Walter L. Wagner]

So, we know of Monosomy and Trisomy, caused either by the nondisjuction of duplicated homologous chromosomes in Anaphase I, or by nondisjuction of the sister chromatids in Anaphase II. However, in both cases, we assume that the error occurs solely in Anaphase I OR Anaphase II. Now, although it would be extremely rare for two nondisjuctions to occur the the exact same genome sector (i.e. A chromosome of pair 21), what would occur if it did? Technically, if nondisjuction occurred to the same genome sector in both Anaphase I and II, then a Pentasomy would occur, in which out of the four potential gametes that would have been produced, one has five homologous chromosomes (Of the specific genome sector in which the nondosjuctions occured), and the rest would have monosomies in that given genome sector. Given that many organisms die in their fetal stages with just simple monosomies and trisomies, I would assume a pentasomy would result in a quick miscarriage after fertilization? What do you think of this possible error of meiosis?

Likely so for animals. Some plants though seem to thrive with polysomy. "Incidences of polysomy have been identified in many species of plants."
http://en.wikipedia.org/wiki/Polysomy Many ferns, and other species also exhibit polysomy, not referenced in that particular article.

 

[GeoffP]

Yeah, wheat does that a fair bit, I think. Knew a guy who had a pentasomid salamander too. Happens.

 

[Walter L. Wagner]

Here's an interesting article about polyploidy in plants driving evolution in plants.

http://www.nature.com/nature/journal/v473/n7345/full/nature09916.html