March 2013 – Page 5

03.14.2013

carbon dioxide, the ocean and mussels

Mussels.

Scientific American reports on the plight of mussels. The ocean is becoming more acidic as man-made carbon dioxide emissions continue to increase. This is having a devastating effect on mussels, making them weaker than before. From the article:

The strength of a mussel, the shellfish’s ability to grasp tightly to rocks, docks and ships despite crashing waves or prying fingers, is legendary. Scientists have even studied how mussels, using slender fibers called byssal threads that are simultaneously hard and stretchy, are able to cling so tight in a rough, wet environment, in hopes that humans could mimic that technology to create strong, flexible textiles.

Now, climate change is impairing that ability to cling. Researcher Michael O’Donnell, an ecologist at the University of Washington, has shown that ocean acidification, a process in which absorbing large amounts of carbon dioxide lowers the pH of oceans, is weakening mussels’ byssal threads.

O’Donnell and his colleagues took bay mussels from San Juan Island, in the Puget Sound, and put them in chambers with seawater at different pH levels. They found that the mussel byssal threads grown in acidified conditions with a pH lower than 7.6 were 40 percent weaker than normal. The research was published Sunday in the journal Nature Climate Change.

03.08.2013

links

Two links for you today:

1. Have you ever wondered how they get grapes to grow so big these days? NPR explains how farmers use a technique called girdling to force the plant to grow larger fruit. This technique along with the use of gibberellic acid, which acts as a kind of growth hormone for the plant, is the reason why the size of grapes in the supermarket is ever increasing. Check it out.

2. And now more on the topic of bees and flowers. Flowering plants use caffeine to lure bees. The New York Times reports on a study showing that flower nectar contains caffeine. Caffeine is a stimulant, and the flower uses it as a kind of reward in an operant conditioning mechanism. The bee gets rewarded with this stimulant drug after pollinating the flower. Having linked the reward to the smell and taste of the flower nectar, the bee searches out more of the flower. The study shows that caffeine helps increase the bee’s memory of the flower’s odor. Have a look!

03.07.2013

salt linked to autoimmune disease

Salt has been linked to the production of TH17 cells by the immune system.

Yesterday, Nature published three research papers announcing that researchers have found a link to salt intake and autoimmune diseases like multiple sclerosis and lupus. In two of the papers, researchers were studying how TH17 cells in the immune system get switched on. These cells are a type of helper T cell that produces an inflammatory protein called interleukin-17 as part of the immune response. While looking for different triggers, the researchers discovered that TH17 activation was linked to the production of a protein called serum glucocorticoid kinase 1, or SGK1, that helps maintain salt levels in other cells. The researchers then saw that mice on a high salt diet had higher levels of SGK1 and more TH17 cells. From Scientific American:

The researchers found that mouse cells cultured in high-salt conditions had higher SGK1 expression and produced more TH17 cells than those grown in normal conditions.

“If you incrementally increase salt, you get generation after generation of these TH17 cells,” says study co-author Vijay Kuchroo, an immunologist at Brigham and Women’s Hospital in Boston, Massachusetts.

The research was then confirmed using a mouse model for multiple scelerosis and in vitro human cell culture. Again from Scientific American:

In the third study, researchers confirmed Kuchroo’s findings, in mouse and human cells. It was “an easy experiment — you just add salt”, says David Hafler, a neurologist at Yale University in New Haven, Connecticut, who led the research.

But could salt change the course of autoimmune disease? Both Kuchroo and Hafler found that in a mouse model of multiple sclerosis, a high-salt diet accelerated the disease’s progression.

All this evidence, Kuchroo says, “is building a very interesting hypothesis [that] salt may be one of the environmental triggers of autoimmunity”.

Whether this holds true in vivo for humans remains to be seen. It’s hard to generalize from in vitro cell culture as the immune system is highly regulated and that regulation can’t be simulated in a culture dish. And as I mentioned earlier this week, in many cases mouse models aren’t always good predictors for human systems.

GOLLYGEE!

Month: March 2013 (page 5 of 8)

carbon dioxide, the ocean and mussels

links

salt linked to autoimmune disease