Syndicate content

Archive - Jan 10, 2014

Cilia in Same Organism Found to Use Different Molecular Motors

Cilia are one of nature’s great multipurpose tools. The tiny, hair-like fibers protrude from cell membranes and perform all kinds of tasks in all kinds of creatures, from helping clear debris from human lungs to enabling single-celled organisms to swim. Now, physicists from Brown University have discovered something that could help scientists understand how cilia have been adapted for so many varied tasks. The study, led by graduate student Ilyong Jung, looked at the cilia of the single-celled, water-dwelling paramecium. Paramecia are covered with cilia that beat like thousands of tiny oars, propelling the creatures through the water. At the same time, cilia around the paramecium’s “oral groove” sweep nutrients inward, providing all-important nourishment. Through a series of experiments, the researchers showed that oral groove cilia appear to have different molecular motors than the rest of a paramecium’s cilia. This is the first time anyone has shown two motor behaviors by cilia in a single cell, says Dr. James Valles, chair of the Department of Physics at Brown and one of the paper’s senior authors. With a bit more study, Dr. Valles hopes this finding could shed light on the molecular mechanisms responsible for these two motor behaviors. “These motors are behaving differently in these two places in the same cell,” Dr. Valles said. “We’re hoping now that we can start pulling the two apart, maybe we can figure out what gives rise to these differences in behaviors. That could help us see why cilia can be so ubiquitous.” The findings were published in the January 7, 2014 issue of the Biophysical Journal. The researchers probed the behavior of the cilia by manipulating the viscosity of the liquid in which the paramecia swam.

Targeting Leishmaniasis “Superspreader” Dogs May Reduce Unnecessary Killing and Help Curb Deadly Disease

A new way to test for the parasite which causes the potentially fatal disease leishmaniasis could help control its spread to humans and stop dogs being needlessly killed in parts of South America. Zoonotic visceral leishmaniasis is a vector-transmitted parasitic infection which can be fatal if left untreated. It generally affects the poorest of the poor, particularly malnourished children in developing countries, with an estimated 200,000 to 400,000 new cases in humans occurring annually, according to World Health Organization (WHO) figures. Dogs have been shown to be the ‘reservoir’ for the parasite, which is transmitted to humans via bites from female sandflies that have fed on blood from infected dogs. In Brazil, tens of thousands of dogs that test positive for anti-Leishmania antibodies are killed every year in an effort to control the disease. However the presence of antibodies does not necessarily mean that the dog is symptomatic or is infectious to sandflies so that it can pass the parasite onto humans. This means that it is likely many dogs are killed unnecessarily, which usually results in dog owners acquiring a new dog, often a puppy that has not encountered the parasite before and that is then likely to become infected, thus helping to drive transmission. Previous studies have questioned the effectiveness of these measures in controlling leishmaniasis in dogs and humans and the policy is also undermined by significant levels of non-compliance among dog owners. An alternative approach is outlined in a new study by scientists at the University of Warwick in the UK who have shown that parasite load – a count of the number of parasites present in a dog’s skin tissue – is related to its infectiousness to sandflies.