Research Notes

Scientists recently uncovered the first gene known to contribute to the genesis of human language. Called FOXP2, this transcription factor might help researchers understand the neurodevelopmental process that culminates in one of humankind's most mysterious attributes. After studying the pedigree of a family affected with a rare monogenetic language-impairment disorder, researchers at the Wellcome Trust Centre for Human Genetics, University of Oxford, mapped the gene to a locus on chromosome 7 and subsequently identified it (C.S.L. Lal et al., "A forkhead-domain gene is mutated in a severe speech and language disorder," Nature, 413:519-23, Oct. 4, 2001). FOXP2 is mutated in affected family members, who have normal intelligence but demonstrate poor grammatical skills and have difficulty speaking, learning, and comprehending language. Genetics center director Anthony Monaco won't say the group identified the language gene. In fact, he says, the gene probably does not directly contribute to the class of language-acquisition disorders known as specific language impairments (SLIs) found in 4 percent of all children. Although FOXP2 probably won't help create a diagnostic tool, says Monaco, "it gives us an entry point into the developmental pathway, which is really a black box. We don't know really what genes or what brain structures are involved in the development of language." As a transcription factor, FOXP2 regulates other potentially interesting genes, he says, possibly those with some role in SLI, as yet unidentified. His group plans to do knockout studies in mice to discern developmental effects, and, with collaborators, to sequence the gene in primates to explore its evolutionary history. --Eugene Russo Spinach as a Vision Aid? It's common knowledge that spinach does a body good; now there may be evidence that it can help vision as well. Scientists from the Oak Ridge National Laboratory (ORNL) and Doheny Eye Institute at the University of Southern California may have found that a protein from Popeye's not-so-secret weapon can replace nonfunctioning light receptors in the eye. Age-related macular degeneration is a loss of sharp, straight-ahead vision caused by photoreceptor deterioration in the center of the retina. Eli Greenbaum, corporate fellow at ORNL, and professor of genomic science at the University of Tennessee, Knoxville, says that a protein from spinach may be able to replace the nonfunctioning photoreceptors. Green plants such as spinach boast light-absorbing chlorophyll, which contains light-processing units, called photosystems, that harness light energy used in photosynthesis. The researchers chose spinach because its photosystems are readily available and can be easily extracted and isolated. A neuroresponse leading to light images begins with the opening of ion channels, causing an action potential within the cell. The 50-60mV required for this process can be provided by a single photosystem. Researchers theorize that by inserting the photosystems into liposomes, the liposome in turn can be put into retinal tissue to act as a molecular prosthesis in photoreceptor cells. Greenbaum is enthusiastic about the possibilities. "The neurological wiring from eye to brain is still intact," he says. "With judicious current and voltage placed in the right spot [of the retina] a light image can be triggered, possibly restoring vision to some blind people." --Hal Cohen A 'Key Suspect' in Alcoholism By increasing the level of dopamine in the rat brain, scientists at the U.S. Department of Energy's Brookhaven National Laboratory may have uncovered a a starting point for the prevention and treatment of alcoholism in humans. (P.K. Thanos et al., "Overexpression of dopamine D2 receptors reduces alcohol self-administration," Journal of Neurochemistry, 78:1094-103, September 2001). Dopamine, a chemical transmitted by brain signals, is necessary for feelings of pleasure and reward. The protein in question, dopamine D2 receptor (DRD2), is primarily located in the nucleus accumbens, the brain's pleasure center. It has been shown that chronic alcoholics have reduced levels of DRD2. With less receptors available for dopamine, the pleasure response signals become blunted and make it more difficult to attain satisfaction. Alcoholic rats injected with DRD2 displayed a significant reduction in alcoholic consumption; the effect on nonalcoholic rats was even greater. Although lead researcher Panayotis Thanos, a professor in the department of medicine at Brookhaven, noted the encouraging results and possibility of obtaining the same response in humans, he says that a cure is not yet right around the corner. "With a complex disease like alcoholism it would be a group of genes we'd have to look at, but it helps to be able to start off with the key suspect." Thanos says that this condition may be associated with other behavior problems as well. "Abuse of anything people find pleasurable--alcohol, drugs, even food--may be attributed to this condition. Because those that are predisposed ... don't get the same rush, they tend to overconsume in an effort to get that feeling of pleasure or reward." --Hal Cohen

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