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The identification of a new vertebrate species has been a relatively rare event during the 20th century. However, scientists from the Smithsonian Institution recently confirmed the discovery of a new species of bird in Gabon, Africa: the olive-backed forest robin (Stiphrornis pyrrholaemus). The bird first was observed in 2001 by scientists involved in a biodiversity assessment program aimed at documenting the organisms that inhabit the tropical forests of central Africa. Genetic testing of several specimens collected for the Smithsonian museum's bird collection confirmed that the olive-backed forest robin is a distinct species, thus bringing Gabon's total number of known bird species to 753. Brian Schmidt, a member of the research team that identified the new species, says of the discovery: "it is definitely a reminder that the world still holds surprises for us."

Primary Source: Schmidt, B.K. et al. (2008) A new species of African Forest Robin from Gabon (Passeriformes: Muscicapidae: Stiphrornis). Zootaxa, 1850:27-42.

Related Resources on BioEd Online:
Downloadable slide sets: Introduction to Biological Classification, Introduction to the Organisms

West Nile virus (WNV) usually is transmitted to humans by infected mosquitoes and can cause a variety of symptoms ranging from flu-like aches and pains to severe and potentially fatal conditions of the central nervous system. The genome of the WNV encodes only ten proteins, suggesting that the virus relies on proteins found in its human host cells in order to infect and replicate. Using a technique known as RNA interference, Howard Hughes Medical Institute investigator Erol Fikrig and his colleagues investigated over 21,000 human genes in an effort to identify the genes and proteins that influence WNV infection. Their study revealed more than 300 human genes that either promote or hinder infection by the WNV. Many of these same genes appear to play a role in infection by a related virus, the dengue fever virus. These findings may lead to new approaches for the treatment or prevention of infection by WNV as well as other related viruses such as the dengue fever, yellow fever, and tick-borne encephalitis viruses.

Primary Source: Krishnan, M.N. et al. (2008). RNA interference screen for human genes associated with West Nile virus infection. Nature.

Related Resources on BioEd Online:
Downloadable slide sets: Introduction to Infectious Diseases, Viruses (NCMI)

Despite the fact that humans spend roughly a third of their lives sleeping, the functions of sleep and the mechanisms that control sleep cycles are not yet completely understood. Recently, Amita Sehgal and her team at the University of Pennsylvania identified a gene that may be required for sleep in fruit flies. A typical fruit fly sleeps approximately 12 hours a day. Through a study of 3,500 flies, Sehgal's team identified a group of flies that survived on little or no sleep. Further investigation revealed that the insomniac flies had mutations in a specific gene, which they named "sleepless." The protein encoded by the sleepless gene may play a role in the homeostatic mechanism that regulates the need for sleep. According to Sehgal, "In the long term, we hope that human equivalents of our gene will be isolated and will not only further our understanding of human sleep, but perhaps also serve as drug targets to promote sleep or treat insomnia."

Primary Source: Koh, K. et al. (2008). Identification of SLEEPLESS, a sleep-promoting factor. Science, 321:334-337.

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Teacher's Activity Guide: Sleep and Daily Rhythms
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Scientists in the Netherlands may have discovered why wounds in the mouth generally heal much faster than comparable wounds on other parts of the body. They found that histatin, a small protein found in human saliva, seems to accelerate the healing process. The research team grew cell cultures of inner cheek epithelial cells in dishes, and then created artificial "wounds" in the cultures by scratching a small piece of the cells off of each dish. After sixteen hours, the "wounds" of cultures treated with human saliva were almost completely closed. In contrast, a large portion of the "wounds" of cultures treated with a control solution (plain isotonic fluid with no additives) remained open. Further investigation revealed that histatin is the major component of human saliva responsible for speeding the wound healing process in this cell culture experiment. This discovery may lead to new treatments for individuals suffering from chronic wounds such as diabetic ulcers.

Primary Source: Oudhoff, M.J. et al. (2008). Histatins are the major wound-closure stimulating factors in human saliva as identified in a cell culture assay. The FASEB Journal, 22.

Obesity has become a worldwide problem. People around the globe seem to be growing heavier with each successive generation. Researchers suspect that obesity in women before and during pregnancy may affect the regulation of body weight in their babies in ways that can be inherited. Robert Waterland and colleagues investigated the effect of maternal obesity in three generations of identical mice-all with the same genetic tendency to overeat. One group of mice was given a standard diet; a second group of mice received a diet supplemented with nutrients that enhance a chemical reaction to silence genes during development (a process known as DNA methylation). The generations of mice on the regular diet grow fatter with each generation. The mice in the group receiving the special supplements did not gain weight. The investigators concluded that epigenetic mechanisms (changes in gene expression that can be inherited) may play a role in promoting heavier and heavier individuals from generation to generation, at least in populations that have a tendency toward obesity.

Epigenetics refers to changes in gene expression that may appear in successive generations, but that do not involve changes in the DNA sequence.

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Presentation: Structures and Functions of Genomes
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While working in Papua New Guinea in the late 1980s, immunologist-biologist David Pritchard noticed that the Papuans infected with a parasite, the Necator americanus hookworm, were less likely to suffer from various autoimmune-related illnesses, such as asthma, than non-infected individuals. Dr. Pritchard hypothesized that the worms survive in their human hosts by producing substances that dampen, or turn off the immune responses that have evolved to expel the parasites - the same immune responses responsible for various allergies and autoimmune-related illnesses. To test this theory, levels of chemicals associated with inflammatory immune responses were compared between two groups: individuals infected with hookworms and placebo recipients. The results suggested that immune system function may indeed be suppressed by parasite infection. However, due to the medical risks associated with hookworm infection, it is not viewed as a reasonable course of treatment for allergy sufferers. Future studies will focus on identifying the molecules that allow hookworms to suppress the immune system in the hopes of developing new drugs to treat individuals suffering from allergies as well as autoimmune conditions such as arthritis.

Harvard University biologists stumbled upon an unusual trait of at least eleven species of frogs in Africa - they can grow claws. The scientists were intrigued by this finding, not only because it is rare for amphibians to have claws, but also because these are particularly unusual claws. Vertebrate claws typically are covered by a sheath of keratin, or if they are covered by skin, they usually are retractable (like the claws of a cat). In contrast, the claws of the African frogs are small, pointed bones at then ends of the frogs' toes, which are connected to the rest of the toe by a collagen-rich sheath. When threatened, the frogs can then flex a certain foot tendon, and the claw-bone separates from the rest of the toe, and bursts through the skin. The biologists now plan to study how the bone is retracted back into the skin, and how the skin regenerates after the claws have returned to the body.

Primary Source: Blackburn, D. C., et al. (2008). Concealed weapons: erectile claws in African frogs. Biology Letters, 4:355-357. 

Traditional cancer treatments damage many healthy cells in addition to cancerous cells. To combat this undesirable side effect, researchers at the University of Texas Southwest Medical Center and University of Texas Dallas are experimenting with new methods of treating cancer cells that do not harm healthy cells. In order to target cancer cells, the researchers are working with immune system proteins called monoclonal antibodies that bind to specific sites on cancer cells. They attached the antibodies to carbon nanotubes (tiny cylinders of carbon atoms), thus creating nanotubes that bind to the surface of cancerous cells, but not healthy cells. When exposed to near-infrared light (a wavelength of light that is invisible to the human eye and can penetrate human tissue up to 1.5 inches), the carbon nanotubes heat up and "cook" the cancer cells, effectively and selectively killing them. Although this technique has not yet been tested in humans, researchers are hopeful that it may greatly improve cancer treatments in the future.

Primary Source: Chakravarty, S. et al. (2008). Thermal ablation of tumor cells with antibody-functionalized single-walled carbon nanotubes. Proceedings of the National Academy of Sciences, 105: 8697-8702.

New skills may be learned in many ways. Simultaneously observing and copying a movement is the most efficient way to learn new motor patterns. However, learning by observation only, without the benefit of practice also occurs. Dartmouth college students participated in a study in which they trained for five days to perform dance sequences set to music videos. Each day they rehearsed one set of dances and passively watched a different set of dance sequences. Activity in the premotor and parietal regions of their brains was observed using functional magnetic resonance imaging (fMRI) prior to and immediately following the five day period. These areas of the brain, in addition to the temporal regions, are active when performing movements and when observing others carry out the same movements. The areas together comprise the "action observation network" (AON) of the brain. The researchers found that both the observational learning and the active physical practice activated areas of the AON in similar ways.

Primary Source: Cross, E.S., Kraemer, D.J., Hamilton, A.F., Kelley, W.M., Grafton, S.T. (2008). Sensitivity of the action observation network to physical and observational learning. Cereb Cortex, 10:1093.

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Downloadable slide set: Introduction to Human Body Systems