Scientists find new genes on male sex chromosomes

by Kate Bourne

Scientists are a step closer to discovering what determines the sex of Australia's iconic platypus and echidna, after an international study involving researchers from the University of Adelaide and UNSW Australia unravelled new genes contained on mammalian Y chromosomes.

The findings of the study, which was led by the University of Lausanne in Switzerland, were today published in the prestigious journal Nature.

The Y chromosome is only found in males and plays a key role in determining male sex. Despite its importance for sex determination, and evolution of the Y chromosome has long been a mystery in most mammals, particularly in monotremes (the platypus and echidna).

Dr Frank Grützner, genetics lecturer and ARC research fellow with the University of Adelaide's School of Molecular and Biomedical Science, says the study saw researchers analyse billions of genetic sequences from 15 and revealed, for the first time, new gene repertoires for all major mammal groups, tracing the evolution of the Y chromosome in unprecedented detail.

"Unravelling on Y has always been a challenging task, and little was known about Y chromosome genes in most mammal species," he says.

"Finding these new genes is a major breakthrough for us. It finally reveals the gene content of the two different Y chromosome systems that evolved in mammals," says Dr Grutzner, who has led research into monotreme sex chromosomes for more than 10 years.

Dr Paul Waters, an ARC fellow in the School of Biotechnology and Biomolecular Sciences at UNSW Australia, says that the X and Y chromosomes started their existence as normal autosomes (non-sex chromosomes) harbouring the same genes. "As the Y chromosome evolved, it withered away, losing most of the 1000 genes that are found on today's X chromosomes. The preserved genes were then recruited into male-specific functions," he says.

University of Adelaide School of Molecular and Biomedical Science PhD student, Deborah Toledo-Flores, says: "the most important aspect of this work for us was to identify more genes on platypus Y chromosomes to reveal new leads about potential sex determining genes in these animals."

"The next step will be to discover which gene on the Y chromosomes determines sex in the platypus and echidna.

"Y chromosomes are vital for male development and fertility and it will be fascinating to gain a better insight into the function that these newly discovered genes have in different species," she says.

More information: Origins and functional evolution of Y chromosomes across mammals, Nature, dx.doi.org/10.1038/nature13151

Related study: phys.org/news/2014-04-liabilit… osome-essential.html

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JVK
1 / 5 (1) Apr 24, 2014
Excerpted from above: "Despite its importance for sex determination, gene content and evolution of the Y chromosome has long been a mystery in most mammals..."

The mystery seems largely due to the failure to acknowledge that cell type differentiation is nutrient-dependent and pheromone-controlled from the advent of sex differences in the cell types of yeasts to sex differences in the cell types of mammals. Thus, the Y chromosome did not evolve, it exists due to ecological variation that results in ecological adaptations, sans mutation-initiated natural selection.

See, for example: Signaling Crosstalk: Integrating Nutrient Availability and Sex http://stke.scien...291/pe28

Feedback loops link odor and pheromone signaling with reproduction
http://www.ncbi.n...16290036

Nutrient-dependent/pheromone-controlled adaptive evolution: a model.
http://www.ncbi.n...24693353
JVK
1 / 5 (1) Apr 24, 2014
Mammalian Y chromosomes retain widely expressed dosage-sensitive regulators http://dx.doi.org...ure13206

Finally, the idea of beneficial mutations is dismissed. "...surviving Y-linked genes form a functionally coherent group enriched for dosage-sensitive, broadly expressed regulators of transcription, translation and protein stability."

Transcription, translation, and protein stability are nutrient-dependent. That has been repeatedly demonstrated in model organisms. Biophysical constraints on protein folding ensure that amino acid substitutions either stabilize DNA or that more nutrient-dependent alternative splicings of pre-mRNA continue to arise until genomic stability is achieved.
anonymous_9001
5 / 5 (1) Apr 25, 2014
more nutrient-dependent alternative splicings of pre-mRNA continue to arise until genomic stability is achieved.


Alternative splicing doesn't do anything to the genome, so no. It's a method of making different protein variants from a given gene following transcription. It doesn't change said gene.
JVK
1 / 5 (1) Apr 25, 2014
The anonymous fool continues to ignore the context of biologically-based cause and effect.

See for example: Understanding and accounting for relational context is critical for social neuroscience http://journal.fr...127/full

and the comment by Dr. Ellis: http://community...._1/51729

"This is absolutely correct and forms part of the larger concept that top-down causation is a key factor not just in the way the brain works but in broader contexts in biology and even physics."

Anonymous fools and idiot minions of biology teachers who have taught them to believe in the pseudoscientific nonsense of mutation-initiated natural selection will not attempt to explain how that is possible in the context of physics, chemistry, and conserved molecular epigenetics. Instead, they will simply say "Nuh-uh, sex chromosomes evolved" when serious scientists provide detailed explanations of biologically-based cause and effect.
anonymous_9001
5 / 5 (1) Apr 25, 2014
And you continue to ignore what the molecular mechanisms you base your model off of actually do and don't do.

I tell you splicing doesn't do what you claim it does and you respond with irrelevant quotes.
JVK
1 / 5 (1) Apr 25, 2014
The quotes are only irrelevant when viewed from the perspective of anonymous fools or idiot minions of biology teachers who do not understand anything about the conserved molecular mechanisms that link sensory input to behavior in species from microbes to man.

"What is life"-lecture: Denis Noble
https://www.youtu...4qaU_yXI
anonymous_9001
5 / 5 (1) Apr 25, 2014
Saying I don't understand the molecular mechanisms while you imply splicing makes changes to the genome. Don't make me laugh.
JVK
1 / 5 (1) Apr 26, 2014
Intragenic DNA methylation modulates alternative splicing by recruiting MeCP2 to promote exon recognition http://dx.doi.org...2013.110

"DNA methylation occurs far more frequently within gene bodies..." which is how alternative splicings of pre-mRNA are linked to cell type differentiation in all cells of individuals across species from microbes to man (in my model).

Nutrient-dependent pheromone-controlled ecological adaptations: from atoms to ecosystems
http://figshare.c...s/994281

However, I have not yet addressed each aspect of quantum physics that must be coordinated for formation of the cell wall. Many people will understand the difficulty of doing that. Anonymous fools and idiot minions of biology teachers like PZ Myers simply attribute everything in every species to mutations, natural selection, and evolution that just happens to violate Laws of Physics, and common sense.
anonymous_9001
5 / 5 (1) Apr 26, 2014
violate Laws of Physics


You seem to be terribly confused. What (allegedly) violates the laws of physics?
JVK
1 / 5 (1) Apr 26, 2014
But wait: Aren't you the anonymous fool who said something that I said about splicing
made you laugh?

The fact that you have never been right about anything makes me laugh. Especially when you tell me I'm confused.
anonymous_9001
5 / 5 (1) Apr 26, 2014
Again: What (allegedly) violates the laws of physics?

And you can't laugh given your blatantly false implication here where you suggest splicing does ANYTHING to the genome:

more nutrient-dependent alternative splicings of pre-mRNA continue to arise until genomic stability is achieved.


Splicing doesn't stabilize genomic material. It's simply a process that mRNA goes through before it's translated.
JVK
1 / 5 (1) Apr 26, 2014
Human adaptations to diet, subsistence, and ecoregion are due to subtle shifts in allele frequency

http://www.pnas.o...abstract

Typically, even an anonymous fool would already have realized the amount of foolishness contributed to this discussion. Unfortunately, it appears that no matter how much accurate information is provided, this anonymous fool will return time-after-time with more foolishness.
anonymous_9001
5 / 5 (1) Apr 26, 2014
Implying splicing has anything to do with the genome is the antithesis of accuracy. It doesn't stabilize the genome. It's completely separate from the genome.

Again: What (allegedly) violates the laws of physics?

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