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Category Archive: Science

Mar 17 2014

Mary’s Monday Metazoan: Melancholy movie

Tympanuchus_cupido_cupido

All the biologists out there know about the heath hen: it’s probably the number one most common example of a recent extinction discussed in considerable detail, because it illustrates so well that extinction is a product of so many factors, from habitat loss to inbreeding to predation to competition to climate shifts to you name …

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Mar 17 2014

Common sense about GM crops

I find myself continually bewildered by the argument against genetically modified food. However, we have no choice, we need to constantly improve the stocks. We have a great deal to gain from growing GM crops. They offer humanity a way to improve food productivity without having to make further inroads into our planet’s wild places …

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Mar 17 2014

Get a jump on the crowd

There’s supposed to be some gigantic announcement coming from the astronomy community today at noon. I think we’ve been burned by the hype a few times before (arsenic life, anyone?), but Sean Carroll thinks this might actually be a significant discovery about Gravitational Waves in the Cosmic Microwave Background. I had no idea what that …

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Mar 16 2014

When your name is prefixed by “reality star”…your ideas are immediately suspect

From the first sentence, I could tell that the opinions of Kristin Cavallari were garbage. Experts warned against the dangers of following celebrity advice after reality star Kristin Cavallari acknowledged Thursday that she and husband Chicago Bears quarterback Jay Cutler decided not to vaccinate their children. When directly asked whether she was opposed to vaccines …

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Mar 15 2014

Missing the point of Giordano Bruno

I’m seeing a lot of silly carping about Neil deGrasse Tyson’s Cosmos — almost all of it is focused on the story of Bruno told in the first episode. The apologists for religion are upset: how dare a science program point out the poisonous influence of religion? Bruno wasn’t really a scientist anyway, so he …

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Mar 14 2014

Friday Cephalopod: You’d be grumpy if your name were ‘Stubby’, too

David Todd

Mar 13 2014

Advice to new parents

Vaccinate your kids. Tara Smith is an expert in infectious diseases, and she also has a new baby (congratulations!) fussing up her house, so she knows what she’s talking about…and she explains why she vaccinated her kids. Just do it. It’s the only smart choice.

Mar 13 2014

I didn’t come from no monkey, updated

Throughout evolution, the gain (+) in the number of copies of some genes and the loss (–) of others have contributed to human- chimp differences.

I was looking over the Discovery Institute’s Evolution News and Views site, prior to forgetting about it. I mentioned that I am forced to revamp my email handling and was going to be blocking a lot of noise from my work address, and as I was reviewing what domains I needed to allow through, I …

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Mar 12 2014

An atheist can be pro-life only by lying about the science

Hemant Mehta let an anti-choice atheist romp about and make her secular pro-life argument, but since he thinks it’s important to give a forum to bullshit but doesn’t think it’s important enough to criticize, I guess I have to. It’s by Kristine Kruszelnicki, president of Pro-Life Humanist, and we’ve dealt with her before; she’s the …

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Mar 11 2014

Pathways to sex

The molecular and genetic events in mammalian sex determination. The bipotential genital ridge is established by genes including Sf1 and Wt1, the early expression of which might also initiate that of Sox9 in both sexes. b-catenin can begin to accumulate as a response to Rspo1–Wnt4 signaling at this stage. In XX supporting cell precursors, b-catenin levels could accumulate sufficiently to repress SOX9 activity, either through direct protein interactions leading to mutual destruction, as seen during cartilage development, or by a direct effect on Sox9 transcription. However, in XY supporting cell precursors, increasing levels of SF1 activate Sry expression and then SRY, together with SF1, boosts Sox9 expression. Once SOX9 levels reach a critical threshold, several positive regulatory loops are initiated, including autoregulation of its own expression and formation of feed-forward loops via FGF9 or PGD2 signaling. If SRY activity is weak, low or late, it fails to boost Sox9 expression before b-catenin levels accumulate sufficiently to shut it down. At later stages, FOXL2 increases, which might help, perhaps in concert with ERs, to maintain granulosa (follicle) cell differentiation by repressing Sox9 expression. In the testis, SOX9 promotes the testis pathway, including Amh activation, and it also probably represses ovarian genes, including Wnt4 and Foxl2. However, any mechanism that increases Sox9 expression sufficiently will trigger Sertoli cell development, even in the absence of SRY.

I was talking about sex and nothing but sex all last week in genetics, which is far less titillating than it sounds. My focus was entirely on operational genetics, that is, how autosomal inheritance vs inheritance of factors on sex chromosomes differ, and I only hinted at how sex is not inherited as a simple …

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