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Posts Tagged ‘DNA’

From Pig Hairs and Genes, A Possible Solution to a Nagging Problem

Even the technological wonders of genetic science can still require some basic, mundane tasks, like cutting pig hairs.

“I spent many, many, many hours snipping the roots of pig hairs,” says Kaitlin Wilson, a Washington State University master’s student in Animal Science. She processed five to seven hairs per pig, in fact, from a total of 272 pigs.

“It was a lot of hair,” says, Wilson, who raised cows and pigs for 4H while growing up on a Connecticut horse farm. “It took me days, hours and hours and hours.”

Pig's tail photo courtesy of

But inside those roots lay just enough DNA to determine each pig’s genetic makeup. And by comparing their DNA, Wilson and colleagues here and in Norway found what they believe is the first genetic basis for a particularly gruesome and costly problem: tail biting.

Pigs biting each other’s tails are a big problem. It’s painful and leaves the victim prone to infection.

“We’re not just talking a little bit,” says Holly Neibergs, an assistant professor of animal genetics and Wilson’s advisor. “We’re talking about a kind of mutilation here. They make these huge holes, which isn’t good.”

Farmers in the United States get around the problem by docking, or cutting, pigs tails. This in turn has been criticized as a cruel practice, which is why it is restricted by the European Union. Meanwhile, many EU pigs are getting their undocked tails bitten. One study found roughly one in every 12 pigs falling victim. Factored out over the EU’s 152 million pigs, that’s roughly 13 million bit pigs.

The behavior is thought to stem from modern facilities that don’t have earth or hay in which pigs can play, forage and root. Frustrated, they bite and chew tails. The biting is reduced with more space and materials to mess about in, but that doesn’t eliminate the problem.

Thinking the behavior might also have a genetic component, Wilson processed hairs from Norwegian crossbred pigs that were either biters, victims or neither. She found that, yes, biting pigs had several similar stretches of DNA in their genes. Moreover, she found that victims also had stretches of DNA in common. Biting’s heritability—the degree to which the behavior can be passed between generations—is significant enough that selective breeding can help reduce the number of biters and their victims, Wilson says.

“Who knew the things they could do with genetics?” says Wilson. “I can only imagine where this is going to go in the future.”

Wilson presented her findings at the 2010 Dr. William R. Wiley Exposition of Graduate and Professional Studies held last month in the CUB. Her poster can be seen here (pdf).

Sequence A Peach

First, a moment of full disclosure. The writer of this item is convinced that the peach is the most remarkable fruit, followed by the Rainier cherry, and only because the Rainier cherry is a lot like a peach.

Ulterior Epicure - Peaches

Ulterior Epicure photo courtesy of Flickr. Click photo to see the Ulterior Epicure photostream.

Now comes word that the peach genome has been sequenced by a team of collaborators that includes Dorrie Main, associate professor of bioinformatics in the WSU Department of Horticulture and Landscape Architecture. This is the first fruit to be sequenced from the Rosaceae family, with implications for relatives like almonds, blackberries, apples, cherries, plums, raspberries, roses, strawberries, plus poplar, citrus and chestnut trees.

Here’s more from Main in the WSU news release, written by our colleague Brian Clark:

“With its small size and high resolution, the peach genome serves as a model. As we’ve been able to identify many interesting genes for breeders, the same genes in other crops can be readily detected and deciphered. The DNA code for ripening or juiciness, for example, is the same in many plants. Understanding the fundamental biology of fruit quality allows enhancement of these attributes for each crop.”

Some discoveries come wrapped in mystery

For more than two decades, researchers have wrestled with something akin to a unified theory of archeology. Put forth by Colin Renfrew, the “farming-language dispersal hypothesis” suggests that farming helped spread language and culture through Europe, Africa, and Polynesia.

The claim, formalized with Australian Peter Bellwood, was appealing in its elegance, if not a bit brash. As Renfrew wrote in the 1996 The origins and spread of agriculture and pastoralism in Eurasia, the ancient distributions of language and farming are so closely related “that an adequate understanding of world genetic diversity and its origins will scarcely be possible without an insight into this fundamental relationship.”

Washington State University molecular biologist Brian Kemp has spent several years extending the hypothesis into the Southwest and Mesoamerica, between central Mexico and Central America. Scholars have long noted a relationship between past and present people in the two regions, the farming of maize, and shared words of the Uto-Aztecan languages.

Writing first for his UC-Davis doctoral dissertation and now the latest Proceedings of the National Academy of Sciences, Kemp explored the possible genetic connections that might be another brick in the wall supporting Renfew’s hypothesis.

Using DNA samples from Uto-Aztecan speakers in the two regions, Kemp looked at both mitochondrial DNA, which is passed down from mothers, and Y-chromosomal DNA, which is held only by men.

Dachalan maize photo courtesy of Flickr. Click image to see photostream.

The mitochondrial DNA doesn’t do much for Renfew’s hypothesis. Women were more closely related to non-Uto-Aztecan speakers in their areas. This, Kemp says, “suggests that no matter which way the language spread, it didn’t spread with females.”

But when he looked at the male DNA, he saw genetic links between men in the two regions. He can’t say which way their genetic material spread. However, he says, “it seems to have been spread by the males, not the females.”

Leaving, well, a mystery. It’s easy enough to imagine male farmers branching out, taking their farming practices, language and genetic variation with them. But a significant expansion of people would seem to need both sexes to reproduce and last more than a generation.

“In the end,” Kemp says, “it’s kind of a frustrating conclusion.”

Petri Sheep

In the winter of 2003, a large herd of bison in an Idaho feedlot was cut in half when a disease outbreak swept through, killing 825 animals.

Two years ago, 19 cattle, most owned by FFA students, died after being shown in Washington’s Puyallup State Fair.

In both instances, Washington State University researchers determined the animals died of malignant catarrhal fever because they had been kept near flocks of sheep, which routinely carry a disease called ovine herpes virus 2. Researchers have known of the disease for decades, but have repeatedly been frustrated in their attempts to grow it in a lab—a major step in developing a vaccine.

James Butler photo courtesy of Flickr. Click photo to view his photostream.

So they use the next best thing to a Petri dish: sheep.

USDA and WSU researchers, writing in an upcoming issue of the journal Veterinary Microbiology, say they have propagated the virus in sheep and for the first time identified specific cells where it can replicate. Their discovery opens the door for growing these cells and the virus in a laboratory setting, where they can then begin developing vaccines.

Naomi Taus, lead author and veterinary medical officer for the Pullman unit of the USDA’s Agricultural Research Service, says she and her colleagues collected secretions from sheep—snot, actually—and aerosolized it to expose other sheep. They then took tissue samples from the sheep and searched for infections by looking for fluorescent markers designed to bind with proteins associated with the virus and certain cell types.

It turns out the virus is entering the sheep at the deepest levels of the lungs in what’s called a type II alveolar epithelial cell—a cell related to skin cells.

Researchers now hope to culture and manipulate these cells in a laboratory setting—a real Petri dish—to develop a vaccine that can be used by the bison industry.

Taus, N.S., Schneider, D.A., Oaks, J.L., Yan, H.,Gailbreath, K.L., Knowles, D.P., Li, H., Sheep (Ovis aries) airway epithelial cells support ovine herpesvirus 2 lytic replication in vivo, Veterinary Microbiology (2008),doi:10.1016/j.vetmic.2010.03.013