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Archive - 2009

Non-Native Beetle Destroying Oaks in Southern California

A beetle first detected in California in 2004 has now attacked 67 percent of the oak trees in an area 30 miles east of San Diego, according to a recent report. The beetle is Agrilus coxalis and the reporting researchers have proposed that it be given the common name: goldspotted oak borer. Land managers and scientists are concerned about further spread of the beetle infestation because oaks are the dominant tree species in the area. Further tree mortality will increase fire danger and decrease wildlife habitat in southern California. The managers and scientists are also concerned that drought and climate change will make more oaks susceptible to this insect that is not native to California. Oak trees have a nearly continuous distribution in the state, reaching from the infestation area north to the Oregon border. “We don't know how the beetle arrived in San Diego County because there's a broad barrier of desert around the localities where it was previously collected in Arizona, Guatemala, and Mexico," said one of the study's authors. "We suspect it was either recently brought to California or somehow expanded its range." There are reports of oak firewood from Mexico frequently being brought into the area in the past 20 years and that could be how it was introduced, the scientist said. Further research is necessary to determine how to halt the spread of the beetle infestation. [Press release]

Nitric Oxide Nanoparticles Show Promise in Treating Staph Infections

Researchers at the Albert Einstein College of Medicine have shown that nanoparticles containing nitric oxide (NO) gas are effective in the topical treatment of drug-resistant Staphylococcus aureus infections in mice. “As the particles take on water, they loosen up and the nitric oxide slowly trickles out, releasing specific amounts of the gas—which is exactly what happens in your body," said a senior author of the study. NO is produced normally by many cells throughout the body and has several important biological functions including killing bacteria, healing wounds, and increasing blood flow by dilating blood vessels. Until now, however, the delivery of NO to infection sites has proven difficult. S. aureus bacteria cause the majority of superficial and invasive skin infections, resulting in more than 11 million outpatient/emergency room visits and 464,000 hospital admissions annually in the U.S. S. aureus infections can be deadly if the bacteria invade the bloodstream, heart, lungs, or urinary tract. As more strains of S. aureus become resistant to common antibiotics, the need for new treatments has become urgent. The encouraging results in mice, followed by additional experiments, may pave the way for clinical trials in humans. [Press release]

April 30th

Synthetic Mimic of Abscisic Acid May Protect Crops from Drought

Scientists have identified a synthetic chemical that has the potential to be used in a spray to protect crops that are facing drought conditions. The chemical is pyrabactin and it mimics abscisic acid (ABA), which is a plant stress hormone that helps crops survive stressful conditions such as drought. For years, scientists have contemplated spraying ABA directly onto crops to enhance their protection in times of stress. But ABA is a costly, complicated, and light-sensitive molecule that has not found use in agriculture. "We screened thousands of chemicals for one that mimics ABA,” said the senior author of the study. “We found pyrabactin activates some of the ABA receptors in plants and is an excellent mimic of ABA. Moreover, unlike ABA, it is stable and easy to make. It therefore suggests a highly effective chemical strategy for improving plants' ability to survive under low-water conditions, potentially benefiting farmers in drought-prone areas worldwide.” The researchers also used the pyrabactin molecule to fish out an ABA receptor, believed to be the first such receptor to be definitively identified. This work was published online in the April 30 issue of Science Express. [Press release] [Science Express abstract]

Novel Delivery Method Might Permit Effective Chlamydia Immunization

Use of a new nanoparticle delivery system has allowed researchers to generate immunity to Chlamydia trachamotis at mucosal surfaces in mice. Chlamydia is the most common bacterial agent of sexually transmitted diseases in humans, accounting for more than a million infections in the United States each year. Infections can lead to reproductive dysfunction and severe local infection. The scientists immunized mice with a bioengineered version of cellular vaults that enclosed a component of Chlamydia. Cellular vaults are barrel-shaped nanoscale capsules found in the cytoplasm of all mammalian cells. The vaults can be engineered to serve as potential therapeutic delivery devices. When the immunized mice were exposed to a vaginal challenge with live Chlamydia, their reproductive tracts were protected from severe bacterial infection. "We are encouraged that our findings could accelerate progress toward developing a vaccine to guard against this infection," said the senior author of the study, which appeared in the April 30 edition of PLoS ONE. [Press release] [PLoS ONE article]

April 29th

Hissing Cockroach Harbors Mold-Fighting Mites

Researchers report that the Madagascar hissing cockroach carries mites that inhibit the growth of molds on the large insect. The scientists suggest that this might reduce the risk of human allergy to these insects, which are popular educational tools and pets. This popularity owes to the insect’s gentle nature, large size, odd sounds, and low maintenance. The mites do not directly destroy the molds, but rather consume water and organic debris that would otherwise be used by the molds. The presence of the mites on the cockroach reduces the presence of molds by at least 50 percent. “By suppressing the molds, the mites have a role in reducing allergic reactions to cockroaches,” said an author of the study, which was published in Symbiosis. [Press release]

Preventive Therapy for Type 1 Diabetes Shows Promise

Scientists in Australia have shown that use of a particular molecule (BCMA) that blocks the action of a B-cell survival hormone (BAFF) may provide a potential preventive therapy for type 1 diabetes. Working with mice that spontaneously develop type 1 diabetes, the researchers found that if BAFF activity was blocked prior to onset of the disease, none of the mice developed diabetes. "This is a remarkable finding, as other B-cell depletion methods tested elsewhere have just delayed or reduced disease incidence," said one of the authors of the study. By removing B-cells from the picture for a while, the researchers indicated, it appears the T regulatory cells are allowed to function as they should, subduing killer T-cells and somehow making them tolerant of the insulin-producing cells in the pancreas. The blocking molecule (BCMA) is already being used in clinical trials for other autoimmune diseases. The research was published online in Diabetes. [Press release]

Oral Delivery System Developed for RNAi

Researchers have shown that interfering RNA (RNAi) enclosed in a yeast-derived particle can be orally delivered to mice to effectively turn off a target gene in cells (macrophages) influencing inflammation. This work has important implications for the promising field of RNAi therapeutics, where progress has been hindered by difficulties in achieving targeted RNAi delivery. "We are very encouraged by these results, which show that oral delivery of a therapeutic dose of small, interfering RNA (siRNA) to a specific cell type in an animal model is possible, and that evidence of gene silencing using this delivery system is measurable," said Professor Michael Czech of the University of Massachusetts Medical School, the senior author of the paper. This work is reported in the April 30 issue of Nature. [UMMS press release] [Nature abstract]

April 28th

DNA Sequence Variant Is Associated with Autism

In a genome–wide association study of the largest autism population sample to date, researchers have identified a DNA sequence variant that is associated with this disorder. The variant lies between the cadherin 9 (CDH9) and cadherin 10 (CDH10) genes on chromosome 5. Both these genes encode neuronal cell adhesion molecules. In particular, when the researchers scrutinized the activity of the CDH10 gene in the fetal brain, they discovered that it is most active in key regions that support language, speech and the interpretation of social behavior. In this association study, all subjects were genotyped with the Illumina HumanHap550 BeadChip with over 550,000 single nucleotide polymorphism (SNP) markers. The results of this study were published in the April 28 advance online edition of Nature. [UCLA press release] [CHOP press release] [UPenn press release] [NIH press release] [Chicago Tribune story] [Nature article]

April 27th

New Transgenic Corn Has Much Higher Vitamin Levels

Scientists have created a transgenic form of corn that contains high levels of three vitamins normally present at much lower levels. The newly developed transgenic form of white corn contains high levels of beta-carotene (a building block for vitamin A), vitamin C, and folate (vitamin B9). Compared to wild-type white corn, the engineered corn contained six times as much vitamin C and twice the amount of folate. Beta-carotene levels in the engineered corn were 169 times the normal amount. The researchers employed a technique involving the use of metal particles coated with genes for production of the vitamins. The authors suggest that their technique could be used to provide vitamin supplementation to cereal crops and help address the multiple vitamin deficiencies that affect nearly half of the world’s population, particularly in developing countries. This research was published online in the Proceedings of the National Academy of Sciences. [PNAS abstract]

Sex Reversal in Humans Associated with Mutation in CBX2 Gene

Researchers describe the birth of a girl with the XY male karyotype, who has a completely normal female phenotype, including uterus and histologically normal ovaries. In mice with a similar phenotype, ablation of the M33 gene, an ortholog of Drosophila Polycomb, causes male-to-female sex reversal. Analysis of the human homolog of M33 (that is, the CBX2 gene) in this girl revealed a loss-of-function mutation in the CBX2 gene. This research was reported in an advance online article in the American Journal of Human Genetics. [AJHG abstract]