A new study describes how a complex genomic rearrangement causes a fascinating phenotype in chickens in which a massive expansion of pigment cells not only makes the skin and comb black, but also results in black internal organs. Published in PLoS Genetics, researchers at Uppsala University, the Swedish University of Agricultural Sciences, North Carolina State University, and National Chung-Hsing University investigated the genetic basis of fibromelanosis, a breed characteristic of the Chinese Silkie chicken. "We have shown that the genetic change causing fibromelanosis is a complex rearrangement that leads to increased expression of Endothelin 3, a gene known for promoting the growth of pigment cells, " explains Ben Dorshorst, one of the authors. The genetic changes underlying the evolution of new species are still poorly understood.
RNA editing is a key step in gene expression. Scientists at Brown University report in Nature Methods that they have engineered a gene capable of visually displaying the activity of the key enzyme ADAR in living fruit flies. To track what they can't see, pilots look to the green glow of the radar screen. Now biologists monitoring gene expression, individual variation, and disease have a glowing green indicator of their own: Brown University biologists have developed a "radar" for tracking ADAR, a crucial enzyme for editing RNA in the nervous system. The advance gives scientists a way to view when and where ADAR is active in a living animal and how much of it is operating. In experiments in fruit flies described in the journal Nature Methods, the researchers show surprising degrees of individual variation in ADAR's RNA editing activity in the learning and memory centers of the brains of individual flies.
Scientists at Dana-Farber Cancer Institute have identified a gene mutation that underlies the vast majority of cases of Waldenstrom's macroglobulinemia, a rare form of lymphoma that has eluded all previous efforts to find a genetic cause. The research (abstracts 261, 300, 434 and 597), to be presented at the American Society of Hematology's 2011 annual meeting on Monday, Dec. 12 at 2:45 p.m. PST, points to an error in a single digit of DNA one of three billion letters in the human genetic code as the leading culprit in Waldenstrom's, and a prime target for new therapies against the disease. The discovery was made by sequencing the genome of tumor cells in Waldenstrom's patients, ┬ reading the cells' DNA letter by letter and seeing where it differed from that of the patients' normal cells.
Amyotrophic lateral sclerosis (ALS; also known as Lou Gehrig's disease ) is an incurable adult neurodegenerative disorder that progresses to paralysis and death. Genetic mutations are the cause of disease in 5% of patients with ALS. Of immense interest, Hongxia Zhou, Xu-Gang Xia, and colleagues, at Thomas Jefferson University, Philadelphia, now show that progressive neuron degeneration can be halted in a rat model of familial ALS linked to mutations in the gene that carries the instructions for making the protein TDP-43. Progressive motor neuron degeneration was stopped when expression of the ALS-associated mutant human TDP-43 was switched off. If expression of the mutant protein was switched off before many motor neurons had degenerated, the rats recovered function. Conversely, if expression was switched off after most motor neurons had degenerated, functional recovery was minimal.
Children with a rather mysterious movement disorder can have hundreds of attacks every day in which they inexplicably make sudden movements or sudden changes in the speed of their movements. New evidence reported in an early online publication from the January 2012 inaugural issue of Cell Reports, the first open-access journal of Cell Press, provides an answer for them. Contrary to expectations, the trouble stems from a defective version of a little-known gene that is important for communication from one neuron to the next. The findings might lead to new strategies for treating a variety of movement disorders, the researchers say. "People with this disorder look and feel normal, " said Louis Pt├ ─ ek of the University of California, San Francisco. "They might be sitting there, get up to go to the kitchen, and start writhing for five or ten seconds.