Syndicate content

Archive - Sep 14, 2011

Date

Beetle Stacks Dummy Eggs to Fool Parasitoid Wasps

They lead modest lives among the palo verde, mesquite, and acacia trees throughout the Southwestern U.S., laying their eggs on seed pods and defending the survival of their offspring against the parasitic wasp species that attacks their eggs before their young can develop. They are the seed beetles Mimosestes amicus, living all around us in the trees of Tucson, and yet remaining all but invisible to our eyes – or nearly so. Now, doctoral candidate Joseph Deas in the University of Arizona's Graduate Interdisciplinary Program in Entomology and Insect Science, along with his faculty advisor Dr. Martha Hunter in the department of entomology, is peering into their world through his microscope and has discovered something novel: The beetles, whose eggs frequently are parasitized by the wasp Uscana semifumipennis, have a strategy to protect their offspring that goes beyond a helpful habit. "They're stacking their eggs in order to protect them from these parasitic wasps," said Deas, whose research was published online in the Proceedings of the Royal Society B on September 14, 2011. The wasps, called parasitoids because they kill their host rather than just taking advantage of its resources, deposit their own eggs inside the beetles’ eggs. The wasp larva gets a head start in life and develops before the beetle larva, hijacking the beetle egg yolk for its own nourishment. "You can tell when an egg has been parasitized because the egg will start to darken and blacken," said Deas. "The beetle larva by that time will never form because all of the yolk is going inside the wasp larva. And then you can see little red eyes in there; the beetles don't have red eyes. It looks very evil." As often happens in science, Deas came upon the discovery of M. amicus' strategy through the course of a different investigation.

Yale Scientists Use Human Uterine Stem Cells to Treat Diabetes in Mice

Controlling diabetes may someday involve mining stem cells from the lining of the uterus, Yale School of Medicine researchers report in a new study published August 30, 2011, in the journal Molecular Therapy. The team treated diabetes in mice by converting cells from human uterine lining into insulin-producing cells. The endometrium or uterine lining, is a source of adult stem cells. These cells generate uterine tissue each month as part of the menstrual cycle. Like other stem cells, however, they can divide to form other kinds of cells. The Yale team's findings suggest that endometrial stem cells could be used to develop insulin-producing islet cells, which are found in the pancreas. These islet cells could then be used to advance the study of islet cell transplantation to treat people with diabetes. Led by Yale Professor Hugh S. Taylor, the researchers bathed endometrial stem cells in cultures containing special nutrients and growth factors. Responding to these substances, the endometrial stem cells adopted the characteristics of beta cells in the pancreas that produce insulin. Over the course of a three-week incubation process, the endometrial stem cells took on the shape of beta cells and began to make proteins typically made by beta cells. Some of these cells also produced insulin. After a meal, the body breaks food down into components like the sugar glucose, which then circulates in the blood. In response, beta cells release insulin, which allows the body's cells to take in the circulating glucose. In this study, Dr. Taylor and his team exposed the mature stem cells to glucose and found that, like typical beta cells, the cultured cells responded by producing insulin. The team then injected diabetic mice with the mature, insulin-making stem cells. The mice had few working beta cells and very high levels of blood glucose.

Engineers Probe Mechanics Behind Premature Aging Disease (Progeria)

Researchers at MIT and Carnegie Mellon University are using both civil engineering and bioengineering approaches to study the behavior of a protein associated with progeria, a rare disorder in children that causes extremely rapid aging and usually ends in death from cardiovascular disease before age 16. The disease is marked by the deletion of 50 amino acids near the end of the lamin A protein, which helps support a cell's nuclear membrane. At MIT, the researchers used molecular modeling — which obeys the laws of physics at the molecular scale — to simulate the behavior of the protein's tail under stress in much the same way a traditional civil engineer might test the strength of a beam: by applying pressure. In this instance, they created exact replicas of healthy and mutated lamin A protein tails, pulling on them to see how they unraveled. "The application of engineering mechanics to understand the process of rapid aging disease may seem odd, but it actually makes a lot of sense," says Dr. Markus Buehler, a professor in MIT's Department of Civil and Environmental Engineering who also studies structural proteins found in bone and collagen. In this new research, he worked with Dr. Kris Dahl, professor of biomedical engineering and chemical engineering at Carnegie Mellon, and graduate students Zhao Qin of MIT and Agnieszka Kalinowski of Carnegie Mellon. They published their findings in the September 2011 issue of the Journal of Structural Biology. In its natural state, a protein — and its tail — exist in complex folded configurations that differ for each protein type. Many misfolded proteins are associated with diseases. In molecular simulations, Qin and Dr. Buehler found that the healthy lamin A protein tail unravels sequentially along its backbone strand, one amino acid at a time.

Amateur Botanists in Brazil Discover New Species of Seed-Burying Plant

José Carlos Mendes Santos (a.k.a. Louro) is a handyman in rural northeastern Bahia, Brazil - one of the areas of the world with the highest biodiversity. Two years ago, he found a tiny, inch-high plant with white-and-pink flowers in the backyards of the off-the-grid house of amateur botanist and local plant collector Alex Popovkin. The little plant was brought home to be grown on a window sill for closer observation. In parallel, work on its identification began. Thanks to solar power and a satellite connection, Popovkin had access to the Internet, and as was his habit, he uploaded some photographs of the plant to Flickr and contacted several taxonomic experts around the globe. The family (strychnine family, or Loganiaceae) and genus (Spigelia) of the plant were soon established, with a suggestion from a Brazilian botanist that it might be a new species. A collaboration was started with Dr. Lena Struwe, a specialist of the plant's family at Rutgers University, who had previously described a species in the gentian family from the Andes named after Harry Potter (apparating moon-gentian, Macrocarpaea apparata), and another after the Inca tribe (the Inca ring-gentian, Symbolanthus incaicus). More collections were made, photographs uploaded and specimens deposited at the State University at Feira de Santana (HUEFS) in Bahia, while Dr. Mari Carmen Molina, a visiting scientist in Dr. Struwe's lab from Spain, extracted the plant's DNA. In collaboration with Dr. Katherine Mathews from Western Carolina University, it was confirmed that the genus was indeed Spigelia, to which pinkroot, an old North American herbal remedy against intestinal parasites, also belongs. Only a few miniscule plants were found in the field the first year.