January 3, 2008, 10:05 PM CT

Insect attack may have finished off dinosaurs

Asteroid impacts or massive volcanic flows might have occurred around the time dinosaurs became extinct, but a new book argues that the mightiest creatures the world has ever known may have been brought down by a tiny, much less dramatic force biting, disease-carrying insects.

An important contributor to the demise of the dinosaurs, experts say, could have been the rise and evolution of insects, especially the slow-but-overwhelming threat posed by new disease carriers. And the evidence for this emerging threat has been captured in almost lifelike-detail many types of insects preserved in amber that date to the time when dinosaurs disappeared.

There are serious problems with the sudden impact theories of dinosaur extinction, not the least of which is that dinosaurs declined and disappeared over a period of hundreds of thousands, or even millions of years, said George Poinar Jr., a courtesy professor of zoology at Oregon State University. That time frame is just not consistent with the effects of an asteroid impact. But competition with insects, emerging new diseases and the spread of flowering plants over very long periods of time is perfectly compatible with everything we know about dinosaur extinction.

This concept is outlined in detail in What Bugged the Dinosaurs? Insects, Disease and Death in the Cretaceous, a book by George and Roberta Poinar, just published by Princeton University Press......... Posted by: Kelly      Read more         Source

January 3, 2008, 9:53 PM CT

Gene therapy can reduce long-term drinking among rodents

Just as the risk of developing alcoholism is strongly influenced by genetic factors, mutations in gene coding such as the aldehyde dehydrogenase (ALDH2*2) allele also appear to protect against the risk. Researchers have only just begun to apply gene-therapy techniques to the alcohol-research field. A proof-of-principle study has observed that administering an anti-Aldh2 antisense gene in rodents can curtail their urge to drink.

Results are reported in the recent issue of Alcoholism: Clinical & Experimental Research

An experiment of nature is observed in some individuals of East Asian origin, who are 66 to 99 percent protected against alcoholism, explained Yedy Israel, professor of pharmacological and toxicological chemistry at the Universidad de Chile, and adjunct professor of pathology, anatomy and cell biology at Thomas Jefferson University in Philadelphia. These individuals carry a genetic mutation that inactivates the aldehyde dehydrogenase-2 enzyme, which is needed to eliminate products of alcohol metabolism. When they drink, they experience nausea, facial redness and a pounding heart. Israel, past president of the U.S. Research Society on Alcoholism, is the studys corresponding author.

Israel added that eventhough gene treatment is predominantly linked to helping bubble babies children who must live in a sterile bubble because they lack all immunity and may die of infections there are presently 1,300 clinical gene-therapy trials for different conditions worldwide......... Posted by: Janet      Read more         Source

January 3, 2008, 9:27 PM CT

Smell-wars between butterflies and ants

Among humans, making yourself smell more alluring than you really are is a fairly harmless, socially accepted habit that maintains a complete perfume industry. However, it is a matter of life and death for caterpillars of large blue butterflies that dupe ant workers into believing them to be one of the ants own larvae. In a publication in the journal Science this week , scientists from the Centre for Social Evolution (CSE) at the University of Copenhagen show that caterpillar deception is also a matter of smell, and that there is an ongoing co-evolutionary arms race in smell similarity between cheaters and their victims.

Most people are familiar with animal confidence tricksters such as cuckoos, which grow up at the expense of 4-5 chicks of hapless songbirds. Less well known, but at least as spectacular, are the large blue butterflies of the genus Maculinea, whose larvae are adopted by ant colonies and deceive the ants into feeding them while letting their own brood starve. Jutland, and the island Ls in particular, are among the last European strongholds of one of these species, the Alcon blue, which has enabled scientists from the CSE to study these spectacular butterflies in great detail.

David Nash, Jacobus Boomsma and his colleagues show that superb chemical mimicry manipulates the ants into neglecting their own brood to care almost exclusively for their caterpillar parasites, but also that the ant hosts can evolve resistance against this exploitation by changing how they smell. However, this only works when the host ants that live close to the initial foodplant of the caterpillars, the rare marsh gentian Gentiana pneumonanthe, do not interbreed with ants from neighbouring sites where the gentian does not occur. In the sites without the foodplant, ant colonies are never parasitized, so ants do not evolve resistance. Any resistance that has evolved in areas with butterflies is not effectively passed on to future generations because it is diluted by the flow of non-resistant genes from the uninfected areas......... Posted by: Kelly      Read more         Source

January 2, 2008, 9:52 PM CT

Missing Evolutionary Link

The crystal structure of a molecule from a primitive fungus has served as a time machine to show scientists more about the evolution of life from the simple to the complex.

By studying the three-dimensional version of the fungus protein bound to an RNA molecule, researchers from Purdue University and the University of Texas at Austin have been able to visualize how life progressed from an early self-replicating molecule that also performed chemical reactions to one in which proteins assumed some of the work.

"Now we can see how RNA progressed to share functions with proteins," said Alan Lambowitz, director of the University of Texas Institute for Cellular and Molecular Biology. "This was a critical missing step."

Results of the study were published in Thursday's (Jan. 3) issue of the journal Nature.

"It's thought that RNA, or a molecule like it, may have been among the first molecules of life, both carrying genetic code that can be transmitted from generation to generation and folding into structures so these molecules could work inside cells," said Purdue structural biologist Barbara Golden. "At some point, RNA evolved and became capable of making proteins. At that point, proteins started taking over roles that RNA played previously - acting as catalysts and building structures in cells"......... Posted by: Janet      Read more         Source

December 27, 2007, 9:18 AM CT

Photo-monitoring whale sharks

Up to 20 meters long and weighing as much as 20 tons, its enormous size gives the whale shark (Rhincodon typus) its name. Known as the gentle giant for its non-predatory behavior, this fish, with its broad, flattened head and minute teeth, eats tiny zooplankton, sieving them through a fine mesh of gill-rakers. Listed as a rare species, relatively little is known about whale sharks, which live in tropical and warm seas, including the western Atlantic and southern Pacific. However, a new study combines computer-assisted photographic identification with ecotourism to study the rare species and suggests whale shark populations in Ningaloo, Western Australia are healthy. The study appears in the Ecological Society of Americas recent issue of Ecological Applications.

West Australian marine scientist Brad Norman (ECOCEAN/Murdoch University) began the study in 1995. Photographs were taken while swimming alongside each whale shark and photographing or video-taping the white lines and spots along the flanks of the animal. Norman teamed up with U.S. computer programmer Jason Holmberg (ECOCEAN, Portland, Oregon) and astronomer Zaven Arzoumanian (USRA/NASA, Greenbelt, Maryland) who adapted software originally used with the Hubble space telescope. The pattern-recognition software developed by Holmberg and Arzoumanian allowed the group to positively identify individual whale sharks. Like a human fingerprint, the speckles and stripes pattern on the skins of whale sharks are thought to beunique to each individual......... Posted by: Kelly      Read more         Source

December 20, 2007, 9:53 PM CT

Study says 2000 tigers possible in Thailand

Thailands Western Forest Complex a 6,900 square mile (18,000 square kilometers) network of parks and wildlife reserves can potentially support some 2,000 tigers, making it one of the worlds strongholds for these emblematic big cats, as per a new study by Thailands Department of National Park, Wildlife, and Plant Conservation and the New York-based Wildlife Conservation Society. The study, which appears in latest issue of the journal Oryx, says that to make these numbers a reality, better enforcement to safeguard both tigers and their prey from poachers is critical.

As per the study, the entire Western Forest Complex currently supports an estimated 720 tigers. These tiger densities were lower than those reported by Wildlife Conservation Society researchers from some protected areas in India with similar habitat, but better enforcement. For example, tiger densities of as a number of as 12 tigers per 100 square kilometers were measured in Indias Nagarahole, Bandipur and Kanha forests, as opposed to four tigers per 100 square kilometers in Thailands Huai Kha Khaeng Wildlife Sanctuary.

The authors of the study conducted intensive surveys of tigers in Huai Kha Khaeng, using camera traps to estimate a population size of 113 individual animals living in the 1,084 square-mile (2,810 square kilometer) protected area......... Posted by: Kelly      Read more         Source

December 20, 2007, 9:20 PM CT

Abstinence by Mutual Consent

Biologists at the University of California, San Diego have discovered a gene in plants that disrupts fertilization only when mutations in the gene are present in both the female and male reproductive cells.

Their discovery, detailed in a paper that appears online today in the journal Current Biology, has been named the "abstinence by mutual consent" mutation because of its unusual properties.

"Mutations that do not allow fertilization are known in plants, but usually these mutations are caused either by a mutation in the female reproductive cells or by a mutation in the male reproductive cells," said Julian Schroeder, a professor of biological sciences at UCSD who headed the study. "In this gene, when only the female carries the mutation, completely normal fertilization occurs, and when only the male carries the mutation, fertilization also occurs. But fertilization is completely disrupted when both male and female reproductive cells carry the mutation simultaneously."

The scientists say the discovery of new genes that control the ability of plants to undergo fertilization could have important applications to plant breeders and conservationists.

"Mutations that cause infertility in crops can provide a powerful tool for breeders who would like to avoid crossing of their plants to related species," said Aurelien Boisson-Dernier, a postdoctoral scholar in Schroeder's UCSD laboratory and the first author of the study. "Conversely breeders would at times like to breed crops by crossing them into distantly related species that however do not allow crossing due to infertility. For example, adding beneficial stress resistance genes from another species may not be possible if the male and female reproductive cells can't communicate properly. Understanding the mechanisms that mediate male-female communication during fertilization could help in circumventing the barrier of such interspecies crosses for breeding new varieties"......... Posted by: Erica      Read more         Source

December 20, 2007, 5:30 AM CT

Parents show bias in sibling rivalry

Most parents would hotly deny favouring one child over another but new research suggests they may have little choice in the matter.

Biologists studying a unique species of beetle that raises and cares for its young have observed that parents instinctively favour the oldest offspring.

The University of Manchester research published in Ecology this month supports the findings of studies carried out on human families but is significant in that it suggests a wholly natural tendency towards older siblings.

The burying beetle Nicrophorus vespilloides has a similar family structure to that of a human family unit in that there are two parents, many offspring and interactions between parents and their young, said Dr Per Smiseth, who led the research in the Universitys Faculty of Life Sciences.

Of course human families are more complex and parent-child relationships are much more sophisticated. However, studying this beetle can help us understand the basic biological principles of how family relationships work.

Our study looked at how the parent beetles mediate competition between different aged offspring in comparison to what happens when the young were left to fend for themselves and indicates that parental decisions are important in determining the outcome of competition between offspring......... Posted by: Kelly      Read more         Source

December 18, 2007, 9:49 PM CT

Ant invaders eat the natives

The Argentine ant, Linepithema humile, is one of the most successful invasive species in the world, having colonized parts of five continents in addition to its native range in South America. A new study sheds light on the secrets of its success.

The findings, from scientists at the University of Illinois and the University of California at San Diego, appear this week in the Proceedings of the National Academy of Sciences.

The Argentine ant is tiny, aggressive and adaptable, traits that have helped it in its transit around the world. Once seen only in South America, the ant is now found in parts of Asia, Australia, Europe, North America and South Africa. It most likely made its way to these destinations on ships carrying soil or agricultural products.

Under the right conditions, the Argentine ant marches through a new territory, wiping out - by eating and out-competing - most of the native ants and a number of other insects. In the process it radically alters the ecology of its new home.

The Argentine ant thrives in a warm climate with abundant water, and is often found on agricultural lands or near cities. But it also invades natural areas, said U. of I. entomology professor Andrew Suarez, principal investigator on the new study. The ant is highly social, and sometimes forms immense "super-colonies" made up of millions workers spread over vast territories. In prior research, Suarez identified a super-colony in California that stretched from San Diego to San Francisco......... Posted by: Kelly      Read more         Source

December 18, 2007, 9:42 PM CT

Frozen hair holds secrets of Yellowstone grizzlies

Locks of hair from more than 400 grizzly bears are stored at Montana State University, waiting to tell the tale of genetic diversity in the Yellowstone Ecosystem.

Ranging from pale blond to almost black, the hair is filed in a chest freezer where the temperature is minus-77.8 degrees. Some of the tufts are almost 25 years old.

The hair will head to Canada in a few months to be analyzed at Wildlife Genetics International in Nelson, British Columbia, said Chuck Schwartz, head of the Interagency Grizzly Bear Study Team based at MSU. The team is monitoring the genetic diversity of the Yellowstone grizzlies over time and wants to know when new DNA appears. The team will also compare the Yellowstone bears with those in the Northern Continental Divide Ecosystem where a similar study has been done.

"An objective of the study is to determine if bears from the Northern Continental Divide Ecosystem migrate to the Yellowstone," Schwartz said.

The Northern Continental Divide Ecosystem includes Glacier National Park, parts of the Blackfeet and Flathead Indian Reservations, parts of five national forests, five wilderness areas and Bureau of Land Management property in northwest Montana. The Yellowstone Ecosystem includes Yellowstone and Grand Teton National Parks, six national forests, and state and private land in portions of Montana, Wyoming and Idaho......... Posted by: Kelly      Read more         Source