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How The Octopus Forms An Elbow
The flexible arm of the octopus has virtually an infinite number of degrees of freedom, allowing a repertoire of movements unmatched by even the human arm.
The new findings, which appear in the April 18th issue of Current Biology, are reported by Tamar Flash of the Weizmann Institute of Science, Binyamin Hochner and German Sumbre of Hebrew University, and Graziano Fiorito of the Stazione Zoologica di Napoli. The extreme motility of the octopus arm demands a highly complex motor control system. Past work from Dr. Hochner's group showed that when retrieving food to its mouth, the octopus actually shapes its arm into a quasi-articulated structure by forming three bends that act like skeletal joints. This puts an artificial constraint of sorts on the arm's movement and simplifies the otherwise complex control of movement that would be needed for the arm to fetch food from a distant point to the octopus's mouth......... Posted by: Kelly Permalink Source Insects That Produce Males From Unfertilized Eggs
One mystery has been the origin of the centrosome, an essential cellular component that is ordinarily derived from the sperm after fertilization. A new study led by researchers at the University of California, Santa Cruz, describes a remarkable process by which the egg cells of Hymenopteran insects make new centrosomes from scratch. The process involves enigmatic cellular structures called accessory nuclei, the function of which has not been explained since they were first discovered in the 1960s. "Centrosomes arise from other centrosomes through duplication, but there is no centrosome in the egg that could give rise to new ones. We found that the accessory nuclei seed the formation of new centrosomes in unfertilized eggs," said Patrick Ferree, a graduate student in molecular, cell, and developmental biology at UCSC. Ferree is first author of a paper describing the new findings in the April 18 issue of the journal Current Biology. Coauthor William Sullivan, professor of molecular, cell, and developmental biology at UCSC, said the findings have implications for understanding basic cell biology, the evolution of Hymenopteran insects, and centrosomal anomalies in cancer cells. The study also shows just how much remains to be discovered about the diversity of life at the cellular level, he said......... Posted by: Kelly Permalink Source A hoverfly having a rest
A hoverfly having a rest. Picture of a hoverfly having a rest......... Posted by: Kelly Permalink Source Red Tide CausesTurtle Death
The culprit is microscopic in size, but its effects are monstrous. Deadly algal blooms- known as "red tide" for the reddish pigments contained in these single-celled organisms at the base of the ocean's food web-have caused the deaths of some 200 sea turtles. The event occurred in November 2005 off the southern coast of El Salvador. Soon after the first appearance of the red-tinged water, some of the region's people fell ill. The government responded by closing shellfish beds in the area, warning against eating seafood from affected areas. The first reports of dead and dying sea turtles washing up on shore occurred in the second week of December. Most of the victims were olive ridley turtles, and a few green and hawksbill turtles were among those stranded. Working quickly, the Salvadoran government and the US Agency for International Development (USAID) called for assistance. WCS veterinary pathologist Dr. Julie White traveled to the site of the crisis in January, where she performed post-mortem examinations on one of the turtles. While there, she also trained Salvadorian colleagues in tissue collection techniques. Samples were then sent to Florida's Fish and Wildlife Research Institute, operated by the National Marine Fisheries Service and the University of Florida. There, scientists diagnosed the problem: high densities of saxitoxin, which is produced by species of algae and sea plankton. The toxin affects the nervous systems of humans and animals alike......... Posted by: Kelly Permalink Source In The New School At Bronx Pupils Have Fins And Scales
The adjustment appeared easy for the 201 herring released into the Bronx River, the only remaining free-flowing river within New York City's borders. After a brief churning of the muddy river bottom, the water's surface calmed to reveal groups of the lean, silvery fish heading downstream along the banks. The herring release is part of a unique partnership to restore the Bronx River. It is also a testament to the efforts of the Bronx Zoo-based Wildlife Conservation Society, NOAA National Marine Fisheries Service, the New York City Department of Parks and Recreation's Natural Resource Group, Lehman College, Bronx River Alliance, and the Connecticut Department of Environmental Protection to transform a long-neglected waterway. The river is now clean enough to provide a suitable habitat for wild fish, and experts hope that the release will soon invite the return of other native regional wildlife that depend on this prey species, such as osprey and herons, as well as game fish like striped bass and bluefish......... Posted by: Kelly Permalink Source Lizard "Third Eye" And Evolution Of Color Vision
Reported in the March 17 issue of Science, their lizard study describes how the "side-blotched" lizard's so-called third, or parietal, eye, distinguishes two different colors, blue and green, possibly to tell the time of day. Specialized nerve cells in that eye, which looks more like a spot on the lizard's forehead, use two types of molecular signals to sense light: those found only in simpler animals, like scallops, and those found only in more complex animals like humans. Eventhough the blue-green color comparison method used by the parietal eye is not one shared by humans, it does reveal one potential step in the evolution of color vision, the Hopkins scientists say. Human light-reception cells responsible for color vision are called cone cells or photoreceptors, and they contain only one kind of pigment per cell - red, green, or blue. A color image results when light-triggered signals in the three different types of cone cells are compared by other nerve cells in the retina as well as the brain. The lizard's parietal eye photoreceptors contain two pigments per cell, blue and green. Having two different pigments allows the cell to respond to two different colors of light and process that information within the same cell......... Posted by: Kelly Permalink Source Gene Decreases Retinal Degeneration In Fruit Flies
In teasing apart the molecular interactions and physiology underlying light perception, the researchers studied a gene they dubbed "Lazaro" that is expressed 15 times higher in the fly eye than the rest of the fly head. They found that this gene is required for a second biochemical pathway that controls the activity of a protein called the TRP channel. TRP channels are found in fruit fly neurons responsible for sensing light. The fly TRP channel is the founding member of a family of related proteins in mammals that are essential for guiding certain nerves during development and for responding to stimuli including heat, taste and sound. By shining bright light onto and recording electrical changes in single nerve cells in the fly eye, researchers found that neurons carrying a mutation in this gene cannot respond as well to light as compared to neurons carrying normal copies of this gene. In fact, the mutant neurons turn off their response to light four times faster than normal neurons. Because Lazaro helps fly TRP channels work at their maximum, it is possible that a Lazaro-like gene in mammals might also play a role in how well mammalian TRP channels work......... Posted by: Kelly Permalink Source Forget A Better Mousetrap
The study, which appears in the latest issue of the journal Conservation Biology, found that rats and mongoose in the Fiji Islands rarely penetrate the forest interior, preferring instead to forage along the forest edges. The study holds potential good news for species like the pink-billed parrotfinch, banded iguana and Fijian land snails which live deep within Fiji's remaining forests. By using bait stations designed to attract rats and mongoose, the scientists discovered that stations over five kilometers (approximately three miles) from the forest edge were rarely visited. "Protection of the few remaining large blocks of natural forests on Pacific islands may be the most cost-effective approach for conserving a number of rare species threatened by rats and mongooses," said WCS researcher David Olson, lead author of the study. Though the authors are unsure on exactly why rats and mongoose seem to shy away from deep forests, they theorize that natural forests have poorer habitats for reproduction for these invasive species than agricultural areas or secondary forests......... Posted by: Erica Permalink Source Extreme Parental Sacrifice
The findings are reported in today 's issue (April 13) of the journal Nature. Hatchlings of B. taitanus-a legless amphibian that looks something like an earthworm-are born with specialized teeth for peeling and eating skin. Their mothers ' skin is specially modified to be especially nutritious, and the young depend entirely on this food source for perhaps as long as four weeks, Nussbaum said. "This form of post-hatching parental care, in which the mother provides nutrition to her hatchlings via her skin, has never been seen before in amphibians, and may be unique among vertebrates to this group of amphibians," said Nussbaum, a professor of ecology and evolutionary biology and a curator in the U-M Museum of Zoology. "Some cichlid fishes are known to provide their hatchlings with nutrition through skin secretions, but this does not include skin feeding". Earlier observations of another species in the same order of amphibians foreshadowed the latest discovery. In the 1990s, the same research team found that newborn Siphonops annulatus had teeth and stayed with their mothers for some time after hatching. Those observations, coupled with the uncommonly pale skin color of mothers caring for young, led Nussbaum and his colleagues to speculate that S. annulatus hatchlings fed on glandular secretions from the mother 's skin, but the researchers never observed such behavior......... Posted by: Kelly Permalink Source Males with elevated levels of testosterone
Over nine breeding seasons, Wendy Reed (North Dakota State University) and her colleagues followed a group of dark-eyed juncos, small mountain songbirds found throughout North America. They injected males with elevated levels of testosterone and found that they had shorter lives but that they were very successful at siring more offspring - even with females who were mated with other males. "The surprising result was that testosterone-treated males had a higher overall fitness than control males," write the authors in a study in the recent issue of American Naturalist. This led to the question of why don't juncos naturally have higher levels of testosterone? Testosterone-treated males produced more offspring, but they were smaller, and smaller offspring had lower postfledging survival. Older, more experienced females preferred to mate with older males and realized higher reproductive success when they did so. While young males treated with testosterone increased their ability to attract older females, it resulted in poor reproductive performance......... Posted by: Kelly Permalink Source |
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