Does this type of expression profile look familiar?
From my limited experience from these types of pan-tissue blots, it would seem like every damn protein is expressed in testes.
Why?
All they do is make sperm (i.e. swimming machines). I mean sure these little guys are complicated, but compared to the liver which plays the role of the body's pharmacist, or the brain with it's supposed unquantifiable complexity, you'd expect that testes should be relatively simple. And as for "making a new human", sperm provide DNA and little else. Most of the important stuff is found in the oocyte. Face it ovaries should be more complicated than testes, but it would seem that at the protein level testes have it all.
Perhaps we need to rethink the role of the testes. Is the homunculus theory correct? Perhaps the testes are just a black hole? (Hmm, that is obviously the wrong metaphor). Or maybe just like a bunch of guys at the local frat house, expression in the testes is just plain sloppy.
So I wasn't too surprised this past weekend when I heard about a new potential therapy for cancer ... the injection of antibodies against testes specific proteins. Yes, it turns out that certain cancers overexpress gene products normally restricted to the testes. In other words, the testes may even express oncogenes. Go figure, half of us carry around two cysts.
(PS Sorry about the lack of updates, I'm in a post-conference experiment blitz. If all works out I'll have some cool stuff soon - and it has nothing to do with testes.)
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the problem is a tough nut to crack.
/turns head and coughs
Have you ever used Unigene's gene expression profile viewer?
Go to Unigene search your protein of interest then select the expression profile search and it gives you a virtual northern blot based on the representation of the transcript in various cDNA libraries, including testes. The gene I study, however, is not expressed there, sorry, but you could test out your hypothesis with most genes and get an answer to your question.
Thanks quitter, I'll do that.
Also I just came back from a seminar, and here is a direct quote. "There are 3 genes encoding JNK. JNK 1 and 2 are ubiquitously expressed, JNK 3 only in the brain heart and testis."
I've often wondered the same thing having seen similar blots in and out of my hands over and over again. Me thinks I do not like the cyst theory though!
I don't have much to offer in terms of proteins, but from what I understand, due to the absence of sexual recombination, the heterogamete (and more specifically, the Y chromosome) is an excellent entry point form HERVs, thus every HERV specific to primates in humans which has genes expressed in at least one organ always seems to have genes expressed in the testes. With birds, the entry point is the heterogametic W chromosome found in females - thus it is the female heterogamete which serves as the common entry point for retroviruses. Likewise, I suspect that due to reduced sexual recombination, HERVs will prefer the regions near the telomeres when they replicate interchromosomally. Does anyone know if this is the case?
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I'm sorry for asking a silly question, but I'm a mathematician with only the faintest idea of what goes on in the lab. Are these blots done with proteins, or with mRNA? If the second, then: are all those proteins actually built?
Reason for asking: a looong shot. Wondering about this, and possible mysteries lurking down there.
What is the temporal pattern of expression of all these genes?
Testis is the only organ in mammals in which clock genes (e.g., PERIOD) are expressed constituitively, i.e., without a circadian pattern. Per1 is thought to have something to do with development in the testis instead.
In each tissue, genes important for the specific function of that tissue (e.g., various enzymes in liver, genes involved in neurotransmission in neurons, etc.) are expressed with a circadian patterns while housekeeping genes are not. I wonder if any gene is expressed with a circadian pattern in the testis and if so, why.
I think you're being a bit dismissive about the hard work the testes do. :)
The Sertoli cells are said to be the most metabolically active cells in the human body, although I can't find a reference on that at the moment. It must be no easy task being a spermatogonium either, what with all the mitotic dividing for your entire life, without just becoming a big tumour. Finally, the task of differentiating from a run-of-the-mill blob into a streamlined and efficient sperm cell, with the incredibly difficult task of reaching the ova and fusing with it, is one that I do not envy, what with the difficulty I have running around the park.
No, being a testis is not easy. In contrast, liver cells just sit around dumping out the same-old same-old, with the occasional task of recovering from a drinking binge, and neurons have the very specific and pathetically simple task of transmitting electrochemical signals.
dileffante,
This is protein expression, but perhaps it's reflective of leaky translation of an RNA based copy of the genome!!! (Having said that there is no evidence of such a mechanism in animal cells and the study you site is this funny phenomena in plants that is hotly debated.)
Coturnix,
I guess that the whole genome may be expressed in testes but not all at once! Interesting twist on the phenomena.
U,
Yes the testes are kinda important, they do produce phenomenal amounts of sperm ... come to think of it, that's
very similar to the nature of a malignant tumour!
Funny phenomena in plants? Look again: this is mice!
Mais, d'accord, d'accord... It's just that RNA has got me a bit bewildered lately, and I'm smelling sci-fi, Lamarck and complex cybernetics everywhere :-)
Sorry 'bout that dileffante, I just assumed that it was the plant stuff, but apparently the revertant phenomena is in mice. Hmm, like the plant stuff it sounds suspicious, but who knows ...