Talk:Sex-determination system
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Article Grading: The following comments were left by the quality and importance raters: (edit · history · refresh · how to use this template) "Sex chromosome" redirects here. Rated "high" as high school/SAT biology content. - tameeria 04:59, 19 February 2007 (UTC) |
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 To-do list for Sex-determination system: |
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The definition in the first paragraph is not very clear. From the definition, one could conclude that a sex-determination system is a method that, when applied to a certain individual, tells you whether that individual is a male or a female. In that sense, a sex-determination system for dogs would be "look if you can find testicles". AxelBoldt
Removed buck-billed from platipuses: platipuses are always duck-billed as there is only one species galf
I believe this reference for duck-billed platipuses, may have come about as the research done on platipuses XY genes was primarly concerning evolution. Hence at once stage the platipuses have had more one species - over time.
A bit on UBE1 and mole voles, from an article on the shrinking Y chromosome, Natural History, September 2002. Vicki Rosenzweig
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[edit] Redirection
Gonosome redirects here, but this article doesn't even mention the term, much less define it! --91.63.214.210 (talk) 19:40, 10 January 2008 (UTC)
[edit] Fish, Amphibians
The article seems a bit sketchy. From a Maths book I see a reference to a 'reverse' xy system in Birds, Fish & Amphibians, however correct that is; presumably it's a reference to what is called the wz system, the article only refers specifically to birds & insects. It would be interesting to know a bit more categorically what different species' systems are.
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I have read information to the effect that the WW:WZ system for birds AND snakes, (i'm not sure about insects) is a reverse xy system in that as the articles says two of the same chromosomes are needed for male determination, instead of the XX style in human.
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I've always heard it discussed as ZW .. rather than WZ. Anyone else?
I have heard of it as the ZW system. And this way makes more sense to me, because it is the first letter that is the base. Just like how the genotypes of the different sexes of humans are XX and XY (where the first letter of both is the same), the genotypes of, say, chickens, are ZZ and ZW (The Z is analogous to the X, because it alone does not signify a gender, whereas the presence of a W chromosome or a Y chromosome does). Kirbytime 00:01, 13 April 2006 (UTC)
[edit] DAX1, Female genes
New research has shown that human females and males come about between a interation of a few genes, and importantly the gene DAX1 if expressed on the X ovum in large amounts can actually cause female development. In any case, female genes in the sex-determination system need to be worked into this article.
[edit] Lists of Organisms
It wouldn't hurt to create an explicit list of the organsims belonging to each reproductive system, perhaps in their own, separate page. "Some insects" (as part of the WZ system) is a bit vague
--Weenie
[edit] I've created articles on the different kinds
I'm linking this article to them, and vice versa:
This is going to turn out great, I know it =) Kirbytime 23:40, 12 April 2006 (UTC)
Uhoh, I have hit a sort of roadblock... ploidy#Haplodiploidy versus Haplo-diploid sex-determination system. Merge them, or what? Kirbytime 23:51, 12 April 2006 (UTC)
[edit] In the News -- Parthenogenic Komodo Lizards
A komodo dragon producing offspring by parthenogenesis at a London zoo is in the news currently. Press reports describe that the offspring must be male.
Please add specifications for Komodo dragons to the article (and the Komodo Dragon article as needed) explaining this female producing males situation.
[edit] Unexpected -- Should Be Explained -- Cross Order Differences/Similarities
What is so striking about this subject is that different systems occur within the same types of animals (for example insects) and that common systems occur across vastly different animal classes.
This is so at odds with what would be expected for descent from common ancestors that it should be specifically pointed out and discussed in a section dedicated to the question. That is, discussed from the point of view of parallel evolution, and the unexpected volatility rather than stability of sex selection systems. (Why isn't there one standard system for all vertibrates for example -- as there is one standard bone structure system?)
From the article currently we might get the impression that the very same genes are being used in these divers species for sex determination -- I suspect it is only the conceptual system that is the same and the actual genes are different. This should be clarified.
More on the relationship of the different actual genes -- to the degree known -- in the different orders (as is currently discussed for birds vs. mammals) would clarify this issue.
[edit] No mention of sex hormones!!
I don't think this artikle is very clarifying. Sex is determined by the sex hormones, oestrogens on the one hand an testosteron on the other hand. In a sensitive phase the indifferent gonads of the embryo (or adult clown fish) will produce either male or female hormones. When this process starts the hormone production will follow a positive feedback loop. The hormone producing cells will produce still more of the hormone and this will influence other factors as the morfology of the germ cells. When the development has a male pathway "Anti Mullerian Duct Factor" will be produced which will eliminate the formation of the Mullerian duct (uterus and ovarian duct).
The sex chromosomes will play a part in the first formation of male or female hormones in the primordial gonad in a manner that is still unclear. The basic formation and determination of gender is however a hormonal affair.
Some fish for instance can be sex reversed when treated a few weeks after the hatching of the eggs with synthetic hormones. This will result in for instance fish which are genetically female (XX) but will function as males. When these fish fertilize a normal female, all female offspring (XX) will result as the XX constitution of the offspring will predetermine them as females.
The temperature effect with crocodiles can be explained in the same manner. Viridiflavus 13:46, 24 February 2007 (UTC)
