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Archive - Apr 21, 2011

New Insight into Survival Strategy of Sleeping Sickness Parasite

Fresh insight into the survival strategy of the parasite that causes sleeping sickness could help inform new treatments for the disease. Scientists have found that the parasite, which can transform itself into either of two physical forms, has developed a careful balance between these. One of these types ensures infection in the bloodstream of a victim, and the other type is taken up by the tsetse fly and spread to another person or animal. The parasite maintains a trade-off between maintaining enough parasites to beat off the immune response and cause infection, and ensuring sufficient parasites to enable the spread of the disease. Researchers at the University of Edinburgh, who carried out the study, used a combination of biological and mathematical techniques to show how the parasite balances production of each of the forms as it causes an infection. Their results enable fresh understanding of how the parasite reacts to its surroundings to ensure its survival in the short term as well as the long-term spread of the disease. Sleeping sickness, which is spread by the bite of the tsetse fly, affects some 30,000 people in sub-Saharan Africa. Many millions more are considered to be at risk. The disease affects people and animals and without treatment is considered fatal. The research, funded by the Wellcome Trust, was published in the April 21, 2011 issue of the journal Cell Host & Microbe. Professor Keith Matthews of the University of Edinburgh, who led the study, said: "Sleeping sickness parasites alter their form in order to ensure their survival and spread.

Close Relative of Arabidopsis Has Much Bigger Genome

It would appear reasonable to assume that two closely related plant species would have similar genetic blueprints. However, scientists from the Max Planck Institute for Developmental Biology in Tübingen, working in cooperation with an international research team have now decoded, for the first time, the entire genome of the lyre-leaved rock cress (Arabidopsis lyrata), a close relative of the thale cress (Arabidopsis thaliana), a model plant used by geneticists. They discovered that the genome of the lyre-leaved rock cress is fifty percent bigger than that of the thale cress. Moreover, these changes arose over a very short period in evolutionary terms. This new high-quality genome analysis will provide a basis for further detailed comparative studies on the function, ecology and evolution of the plant genus Arabidopsis. Genome size among the different species of the plant kingdom varies significantly. At the upper end of the currently known spectrum, scientists have identified the herb Paris or true-lover’s knot (Paris quadrifolia), whose genome is a good thousand times longer than that of the carnivorous plants from the genus Genlisea. However, these plants are so distantly related that it is almost impossible to identify the evolutionary forces at work in the individual species. Therefore, researchers from Dr. Detlef Weigel’s Department of Molecular Biology at the Max Planck Institute for Developmental Biology in Tübingen working in cooperation with an international research team selected for their genome study a species closely related to the thale cress (Arabidopsis thaliana), probably the most widely studied flowering plant in genetics. The species in question was lyre-leaved rock cress (Arabidopsis lyrata) which, unlike thale cress, is unable to self-fertilize.

Placenta Synthesizes Serotonin for Developing Fetus

Research at the Keck School of Medicine of the University of Southern California's (USC) Zilkha Neurogenetic Institute shows for the first time that the human placenta plays an active role in synthesizing serotonin, paving the way to new treatment strategies that could mitigate health impacts such as cardiovascular disease and mental illness. The groundbreaking findings, conducted with researchers from Vanderbilt University as part of a Silvio Conte Center of Excellence grant from the National Institute of Mental Health, offer conclusive evidence that the placenta provides serotonin to the fetal forebrain, not through the mother's blood supply, as theorized for the past 60 years. The research was published in Nature on April 21, 2011. "Our research indicates that the placenta actually synthesizes serotonin, and the serotonin is released from the placenta into the fetal bloodstream where it can reach the fetal brain," said lead author Dr. Alexandre Bonnin. "The placenta was seen as a passive organ, but we now know that it has significant synthetic capabilities and has a much more critical role in developmental programming of the fetus than previously thought.” Dr. Bonnin's work with Dr. Pat Levitt, director of the Zilkha Neurogenetic Institute and corresponding author on the paper, included the invention of a unique technology known as a "placentometer" that monitors substances that pass through the mouse placenta from mother to fetus. This technology can incorporate genetic models of human disease, and could lead to targeted therapies that treat the mother without affecting the fetus, or vice versa. "The findings by Dr.