January 12, 2009, 6:21 AM CT

Reverse evolution in real-time

In his book, Wonderful World, Stephen Jay Gould writes about an experiment of 'replaying life's tape', wherein one could go back in time, let the tape of life play again and see if 'the repetition looks at all like the original'. Evolutionary biology tells us that it wouldn't look the same the outcome of evolution is contingent on everything that came before. Now, researchers at the Instituto Gulbenkian de Cincia (IGC) in Portugal, New York University and the University of California Irvine, provide the first quantitative genetic evidence of why this is so.

In this study, would be published online this week in the journal Nature Genetics, Henrique Teotnio and colleagues recreated natural selection in real-time, in the laboratory (rather than based on inferences from fossil records or from comparing existing natural populations) and provide the first quantitative evidence for natural selection on so-called standing genetic variation a process long believed to be operating in natural populations that reproduce sexually but which, until now, had never been demonstrated.

The scientists used laboratory-grown populations of fruit fly (Drosophila melanogaster), derived from an original group of flies, harvested from the wild back in 1975. These ancestral flies were grown in the laboratory, for two decades, under different environmental conditions, (such as starvation and longer life-cycles) so that each population was selected for specific characteristics. Henrique Teotnio and colleagues placed these populations back in the ancestral environment, for 50 generations, to impose reverse evolution on the flies, and then looked at the genetic changes in certain areas of chromosome 3 of these flies......... Posted by: Kelly      Read more         Source

January 8, 2009, 10:09 PM CT

When workers try to cheat

In ant society, workers normally give up reproducing themselves to care for their queen's offspring, who are their brothers and sisters. When workers try to cheat and have their own kids in the queen's presence, their peers swiftly attack and physically restrain them from reproducing.

Now, a newly released study published online on January 8th in Current Biology, a Cell Press publication, explains just how the cheaters get caught red-handed. Experimental evidence shows that chemical hydrocarbons produced by those sneaky sorts are a dead giveaway of their fertility status.

The findings represent the first direct evidence that cuticular hydrocarbons are the informational basis for the ants' reproductive policing, said Jrgen Liebig of Arizona State University.

Earlier studies had suggested that other aspects of reproduction in insect societies are regulated through cuticular hydrocarbon signals. Liebig's team and others showed that the chemical profiles are correlated with fertility in queens and workers in a number of species of ants, some wasps, and bees. They also observed that workers use hydrocarbons to discriminate between eggs laid by workers and queens. The chemicals are used in other contexts as well, including nestmate recognition and sexual attraction......... Posted by: Kelly      Read more         Source

January 8, 2009, 10:02 PM CT

Ancient odor-detecting mechanism in insects

The work, led by Leslie B. Vosshall, head of the Laboratory of Neurogenetics and Behavior, revamps traditional ideas regarding the roles of ionotropic glutamate receptors, proteins that reside deep in the brain at the synapses. There, they grab glutamate molecules and quickly relay messages from one nerve cell to the next, helping animals learn, move and remember. But Vosshall's group now shows that insects do not relegate these receptors to the depths of the brain. They also put them to use elsewhere: in the nose.

"On the surface it's a completely absurd idea," says Vosshall, who is also a Howard Hughes Medical Institute investigator. "We know what these proteins do; they sit at the synapse and mediate fast neuronal communication. So the idea that the fly has massively expanded the number of these receptors and positioned them to interact with small molecules in the air seems very strange. But if you think about it, it makes sense. The process is the same, but rather than grabbing small molecules at the synapse, they're grabbing small molecules from the air."

The project began two years ago, when Vosshall and Richard Benton, then a postdoc in her lab, noticed a group of six ionotropic glutamate receptor genes while sifting through the fly genome. Eventhough this group was recognized 10 years ago, ever since the genome was sequenced, the genes did not have a known function, in part because it was assumed they must be similar to any other ionotropic glutamate receptor deep in the fly brain. But to Vosshall and Benton, who is now at the Center for Integrative Genomics in Lausanne, Switzerland, that didn't matter......... Posted by: Kelly      Read more         Source

January 8, 2009, 9:31 PM CT

Hind wings help butterflies make swift turns

New tires allow race cars to take tight turns at high speeds. Hind wings give moths and butterflies similar advantages: They are not necessary for basic flight but help these creatures take tight turns to evade predators.

"To escape a predator, you don't have to be fast, you just have to be more erratic," said Tom Eisner, a world authority on animal behavior, ecology and evolution and the Jacob Gould Schurman Professor Emeritus of Chemical Ecology at Cornell. Eisner is co-author of a study on butterfly wings recently reported in the Proceedings of the National Academy of Sciences (105: 43).

The study proposes that in the course of evolution, the ability of butterflies to evade predators became linked with bright coloring, as an added protection. In evolutionary terms, gaudy colors are commonly a sign to such predators as birds that a prey species has a protective quality, such as a bad taste or great agility, and that chasing them isn't worth the energy. Anyone who has tried to net a colorful butterfly knows they are hard to catch, but this is the first study to show that a butterfly's hind wings are responsible for making them evasive.

Eisner and the paper's main author, Benjamin Jantzen, (M.S. physics '02), a doctoral student in philosophy of science at Carnegie Mellon University, clipped off the hind wings of butterflies and then filmed their flight using two cameras to get three-dimensional views of their flight trajectories; then they analyzed and plotted on a computer the insects' flight velocity, acceleration, how fast they changed direction, the curvature of their path and more......... Posted by: Kelly      Read more         Source

January 8, 2009, 8:58 PM CT

Mosquitoes create harmonic love song

That pesky buzz of a nearby mosquito is the sound of love, researchers have known for some time. But a new Cornell study reports that males and females flap their wings and change their tune to create a harmonic duet just before mating.

Cornell entomologists have discovered that male and female mosquitoes (Aedes aegypti), which can spread such diseases as yellow and dengue fevers, "interact acoustically with each other when the two are within earshot -- a few centimeters of each other," said Ron Hoy, professor of neurobiology and behavior.

The study is available online today (Jan. 8) and will be published in a recent issue of Science, said Cornell associate professor of entomology and mosquito expert Laura Harrington, a co-senior author on the study with Hoy.

"The frequency at which males and females converge is a harmonic or multiple of their wing-beat frequencies, which is approximately 400 hertz [vibrations per second] for the female and 600 hertz for the male," said Hoy.

The mating duet, generated just before the couple mates on the fly, settles at around 1,200 hertz -- roughly an octave and a half above concert A (the pitch to which instruments are tuned -- the A that has a frequency of 440 hertz and is above middle C). "That is significantly higher than what was previously believed to be mosquitoes' upper hearing limit," he added......... Posted by: Kelly      Read more         Source

January 8, 2009, 8:56 PM CT

Microbial Ropes Grow Slowly

Deep inside the Frasassi cave system in Italy and more than 1,600 feet below the Earth's surface, divers found filamentous ropes of microbes growing in the cold water, as per a team of Penn State researchers.

"Sulfur caves are a microbiology paradise. A number of different types of organisms live in the caves and use the sulfur," says Jennifer L. Macalady, assistant professor of geosciences. "We are trying to map which organisms live where in the caves and how they correspond to the geochemical environment".

In this process, Macalady and her team discovered a previously unknown form of biofilm growing in the oxygen-deficient portion of the lake.

"The cave explorers had seen these strange biofilms," says Macalady. "So we asked them if they could get us a sample".

The Frasassi cave system is located north of Rome and south of Venice in the Marche region. These limestone caves are like New Mexico's Carlsbad Caverns and Lechuguilla Cave, but in those caves, sulfur entered the caves from oil and gas reserves, while in Italy, the sulfur source is a thick gypsum layer below. Having sulfur in the environment allows sulfur-using organisms to grow.

The scientists received about the weight of two paper clips of the strange rope to analyze. They reported the results of their DNA sequencing today (December 19) at the American Geophysical Union Conference in San Francisco......... Posted by: Janet      Read more         Source

January 8, 2009, 8:46 PM CT

Shade coffee provides genetic diversity

Here's one more reason to say "shade grown, please" when you order your morning cup of coffee. Shade coffee farms, which grow coffee under a canopy of multiple tree species, not only harbor native birds, bats and other beneficial creatures, but also maintain genetic diversity of native tree species and can act as focal points for tropical forest regeneration.

The finding comes from a study published by University of Michigan scientists Shalene Jha and Christopher Dick in the Dec. 23 issue of the journal Current Biology.

Jha, a graduate student whose main interest is insects, initially wanted to find out whether shade coffee farms nurture native pollinators such as stingless bees. When she began her fieldwork in Chiapas, Mexico, she focused on a particular tree, Miconia affinis, which is pollinated by an unusual method known as buzz pollination. In order to release pollen from its flowers, bees grab hold and vibrate their flight muscles, shaking the pollen free. Non-native species such as Africanized honeybees don't perform buzz pollination, but native bees do, said Jha, "so I thought Miconia, which requires buzz pollination and is common both in forests and on coffee farms, could be a bio-indicator of how well native bees are pollinating native plants".

As she spent time in the field, however, Jha realized that the story of how Miconia trees spread into coffee farms and how their dispersal affects the tree population's genetic diversity begged to be addressed before she proceeded with the pollen studies. With guidance from Dick, an assistant professor of ecology and evolutionary biology who studies genetic diversity patterns in tropical tree species, Jha collected and analyzed DNA samples from Miconia trees growing in a network of coffee farms and forest fragments......... Posted by: Erica      Read more         Source

January 8, 2009, 7:51 PM CT

Mother Nature Knows Nano Technology

The future of the nanotechnology field depends on our ability to reliably and reproducibly assemble nanoparticles into 3D structures we can use to develop new technologies. As per Hao Yan and Yan Liu at Arizona State University, the greatest challenges in this burgeoning field include control over nanoscale 3D structure and imaging these tiny materials.

"The ability to build predicted structures and provide experimental feedback to current theories is critical to the nanotechnology field," said Yan.

One approach to production of nanoscale architecture is creation of nanoparticles that assemble themselves into the desired structure. DNA molecules are an elegant biological example of small particles that self-assemble to form higher order 3D structures.

Inspired by this prototype, Yan and his colleagues looked to Mother Nature to solve their nano-sized problem. They attached gold nanoparticles to DNA, taking advantage of its self-assembling biochemical properties to engineer nanotubes that form many different 3D structures. The scientists manipulated nanotube size and shape by changing the size of the gold particles attached to the DNA or the DNA structure itself. Anchi Cheng at the Scripps Research Institute contributed to the project by imaging the 3D conformations of nanotube structures using cryo-Electron Tomography......... Posted by: Janet      Read more         Source

January 7, 2009, 11:55 PM CT

Spookfish uses mirrors for eyes

A remarkable new discovery shows the four-eyed spookfish to be the first vertebrate ever found to use mirrors, rather than lenses, to focus light in its eyes.

Professor Julian Partridge from the University of Bristol, said: "In nearly 500 million years of vertebrate evolution, and a number of thousands of vertebrate species living and dead, this is the only one known to have solved the fundamental optical problem faced by all eyes - how to make an image - using a mirror".

While the spook fish looks like it has four eyes, in fact it only has two, each of which is split into two connected parts. One half points upwards, giving the spookfish a view of the ocean - and potential food - above. The other half, which looks like a bump on the side of the fish's head, points downwards into the abyss below. These 'diverticular' eyes are unique among all vertebrates in that they use a mirror to make the image.

Very little light penetrates beneath about 1000m of water and like a number of other deep-sea fish the spookfish is adapted to make the most of what little light there is. At these depths it is flashes of bioluminescent light from other animals that the spookfish are largely looking for. The diverticular eyes image these flashes, warning the spookfish of other animals that are active, and otherwise unseen, below its vulnerable belly......... Posted by: Kelly      Read more         Source

January 7, 2009, 11:47 PM CT

Human structures leads creatures into peril

Smooth, dark buildings, vehicles and even roads can be mistaken by insects and other creatures for water, as per a Michigan State University researcher, creating "ecological traps" that jeopardize animal populations and fragile ecosystems.

It's the polarized light reflected from asphalt roads, windows -- even plastic sheets and oil spills -- that to some species mimics the surface of the water they use to breed and feed. The resulting confusion could drastically disrupt mating and feeding routines and lead insects and animals into contact with vehicles and other dangers, Bruce Robertson said.

An ecologist studying at the W.K. Kellogg Biological Station in Hickory Corners, north of Kalamazoo, Robertson said polarized light reflected from man-made structures can overwhelm natural cues to animal behavior. Dragonflies can be prompted to lay eggs on roads or parking lots instead of water, for example, and such aquatic insects are at the center of the food web. Insect population crashes can impact higher levels of the food chain.

"Any kind of shiny, black object -- oil, solar cells, asphalt -- the closer they are to wetlands, the bigger the problem," he said.

Predators following misdirected insect prey then also can find themselves in danger......... Posted by: Kelly      Read more         Source