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Date: 11.21.2012

11.21.2012

turkey science


In the spirit of Thanksgiving I bring you some turkey science. Today’s turkeys are genetically all very similar to each other. They have less genetic variation than most other domesticated animals. From Popular Science:

What’s more, the turkeys on our dinner table this week have less genetic variation than both their wild counterparts and other domesticated animals, including pigs and chickens. The lack of variance can be explained by the way Americans like their turkeys–big and huge-breasted. Variation in genes that code for those traits can lead to more scraggly and therefore less appetizing turkeys.

To figure this out, SI scientists sequenced the full genomes of birds from seven different commercial turkey-breeding lines, as well as the genomes of three south Mexican turkeys collected in 1899. Those turkeys’ DNA was extracted at the National Zoo from samples stored in the Smithsonian’s collections. Fleischer said the museum specimens worked surprisingly well. This will help geneticists nail down the genes involved in turkey domestication and enfattening.

11.21.2012

more telomere and longevity news

Seychelles Warbler

Piggybacking on the report I mentioned last week is this from Science News:

A study of Seychelles warblers living on a small island in the Indian Ocean suggests that the length of telomeres — bits of DNA that cap chromosome ends — can predict a bird’s chance of dying better than its chronological age can. Warblers with shorter telomeres were less likely to survive another year, especially if the truncation happened rapidly, David S. Richardson, a molecular ecologist at the University of East Anglia in Norwich, England, and colleagues report online November 20 in Molecular Ecology. …

Young birds started with roughly the same size telomeres, Richardson says. But some warblers’ telomeres shorten faster than others as the birds age. Although there are no predators on Cousin Island, the protected area in the Seychelles where the study was conducted, life does present other stresses and strains, Richardson says. Some parts of the island may have less food. Birds may get infected with malaria parasites. And reproduction and caring for young may take its toll on female birds.

So far, the researchers haven’t linked any of these challenges to telomere length, but that’s one of the next items on the research plan, Richardson says. He’d also like to know if parents can pass along shortened telomeres to offspring.

It’s also not clear whether telomere shortening leads to poor health and death, or if truncated chromosome tips are a side effect of stress and disease. Even if losing a little off the chromosome tips isn’t enough to kill outright, “telomeres might be acting as an indicator of the sort of hard life you’re going through,” Richardson says.

11.21.2012

how dogs smell

This was brought to my attention by Andrew Sullivan, who shares this excerpt from Virginia Hughes’ blog:

Dog olfaction

 

 

 

 

 

 

 

Human noses aren’t built to take in much from that pungent world. When we’re trying our damnedest to smell something, we inhale deeply. But as soon as we exhale, we lose the scent. The airflow patterns of the dog nose are strikingly different: They have one air passage for breathing and another for smelling. …

The dog’s nostrils are in gray on the left; the rest shows the inside of the nose. The brownish area on the right is where all of the smelling, or olfaction, happens — all those receptors sensing different types of odor molecules. The red lines represent the airflow paths when the dog is smelling, whereas the blue lines show the paths during breathing.

You can see that because of the nose anatomy, a dog can quickly move odor molecules to the back, letting them linger atop olfactory receptors. The front area, meanwhile, stays clear for continued breathing. Our olfactory receptors, in contrast, sit at the top of our nasal cavity, easily perturbed as we breathe out.

//psomtenga.net/4/4535925