How Evolution Can Allow For Large Developmental Leaps. How evolution acts to bridge the chasm between two discrete physiological states is a question that's long puzzled scientists. Most evolutionary changes, after all, happen in tiny increments: an elephant grows a little larger, a giraffe's neck a little longer. If those tiny changes prove advantageous, there's a better chance of passing them to the next generation, which might then add its own mutations. And so on, and so on, until you have a huge pachyderm or the characteristic stretched neck of a giraffe. But when it comes to traits like the number of wings on an insect, or limbs on a primate, there is no middle ground. How are these sorts of large evolutionary leaps made?
Global Model For The Origin Of Species Independent Of Geographical Isolation. The tremendous diversity of life continues to puzzle scientists, long after the 200 years since Charles Darwin's birth. However, in recent years, consistent patterns of biodiversity have been identified over space, time organism type and geographical region. Two views of the process of "speciation" -- the evolutionary process by which new biological species arise -- dominates evolutionary theory. The first requires a physical barrier such as a glacier, mountain or body of water to separate organisms enabling groups to diverge until they become separate species. In the second, an environment favors specific characteristics within a species, which encourages divergence as members fill different roles in an ecosystem.
Insights Into Failed HIV-1 Vaccine Trial. Following the disbandment of the STEP trial to test the efficacy of the Merck HIV-1 vaccine candidate in 2007, the leading explanation for why the vaccine was ineffective – and may have even increased susceptibility to acquiring the virus – centered on the hypothesis that high levels of baseline Ad5-specific neutralizing antibodies may have increased HIV-1 acquisition among the study subjects who received the vaccine by increasing Ad5-specific CD4+ T-cells that were susceptible to HIV-1 infection. Now, a study by Dan Barouch, MD, PhD, and a scientific team at Beth Israel Deaconess Medical Center (BIDMC), reported in the July 20 Advance Online issue of Nature Medicine, shows this was likely not the case.
South Africa launches AIDS vaccine clinical trials. South Africa announced the launch of clinical trials of the first AIDS vaccines created by a developing country with assistance from the U.S. on Monday. It represented a feat by scientists who overcame skepticism from colleagues and from some political leaders who shocked the world with unscientific pronouncements about the disease. "It has been a very, very hard journey," lead scientist Professor Anna-Lise Williamson of the University of Cape Town said at Monday's ceremony, attended by American health officials who gave technical help and manufactured the vaccine at the U.S. National Institutes of Health.
NIH Issues Research Plan on Fragile X Syndrome and Associated Disorders. The National Institutes of Health has developed a research plan to advance the understanding of fragile X syndrome and its associated conditions, fragile X-associated tremor/ataxia syndrome and fragile X-associated primary ovarian insufficiency. Fragile X syndrome causes intellectual and developmental disabilities and results from a mutation in a gene on the X chromosome.
The plan puts forward goals to guide future research, setting research priorities for each of the conditions. A major priority of the plan is to investigate the biological processes underlying all three disorders and how to better diagnose and treat them. Other priorities are studying how widespread the gene variations are in the population and how the three conditions affect families.
"NIH’s research efforts have made great strides in understanding these conditions," said Raynard S. Kington, M.D., Ph.D., acting director of NIH. "We now intend to build on these advances."
Although the three disorders have very different symptoms, all result from variations in the same gene, known as the Fragile X Mental Retardation 1 (FMR1) gene. Full mutation of the gene means that cells do not produce a protein involved with communications between neurons in the central nervous system. The resulting disorder, Fragile X syndrome (FXS), occurs in approximately one in 2,500 births. People with FXS often have intellectual disabilities ranging from mild to severe. They may also have emotional and behavioral problems, including attention problems, hyperactivity, anxiety, aggression, and autism or autism spectrum disorder.
Children With Fetal Alcohol Spectrum Disorders (FASD) Have More Severe Behavioral Problems Than Children With Attention Deficit Hyperactivity Disorder (ADHD), Study Finds. Children with fetal alcohol spectrum disorders (FASD) have a high risk of psychiatric problems, particularly attention deficit hyperactivity disorder (ADHD), conduct disorder, or both. Often children with FASD are initially diagnosed with ADHD. A new study is the first to examine a range of cognitive factors and social behavior in children with FASD and ADHD, finding that those with FASD have significantly weaker social cognition and facial emotion-processing abilities. Results will be published in the October issue of Alcoholism: Clinical & Experimental Research and are currently available at Early View.
"Behaviorally, FASD and ADHD can look quite similar, particularly with respect to problems with very limited attention, physical restlessness, and extreme impulsivity," explained Rachel Greenbaum, a clinical psychologist with the Children's Mental Health Team at Surrey Place Centre in Toronto, who conducted the study as part of her doctoral dissertation.