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Evolution At The Tips Of Chromosomes
Acting as caps on the ends of each chromosome, telomeres are composed of repetitive DNA and shelterin, a protective protein complex protects. Titia de Lange's lab has identified many of the components of shelterin and studies how its components work together to ensure that chromosome ends are not recognized as DNA breaks. Previous work from the de Lange lab showed that TRF2, a shelterin protein that binds to the duplex part of the telomere, is crucial for telomere protection. Without TRF2, telomeres activate a DNA damage signal and are repaired by the same pathways that act on DNA breaks. TRF2 brings a second shelterin protein, POT1, to the telomeres. Because POT1 binds to single-stranded telomeric DNA present at the very end of the chromosomes, the de Lange lab asked how POT1 contributes to the protection of telomeres. "We had previously removed TRF2 from mouse cells and seen many dramatic phenotypes," says de Lange, "all of the telomeres ligate together; there is a massive DNA damage response and the cells basically die. We argued that if the function of TRF2 was to bring POT1 to the DNA, then we should observe the same phenotype if we removed POT1"......... Posted by: Sean Permalink Source On The Trail Of Columbus' Sunken Ships
A 300-pound kedge anchor is about to be brought to the surface.
Despite these setbacks, Indiana University archaeologists are confident they are closer to discovering some of Christopher Columbus' lost ships -- and the answer to a 500-year-old mystery, "What was on those ships?". "The discovery of a Columbus shipwreck, let alone the finding of the flagship Mariagalante, would be a tremendous contribution to maritime archaeology," said Charles Beeker, director of Academic Diving and Underwater Science Programs in IU Bloomington's School of Health, Physical Education and Recreation. "Perhaps more important would be the cargo. Were the ships laden with native Taino Indian artifacts heading to Spain? Such a find would shed new light on the nature of the contact period between the Old and the New Worlds." Earlier this summer, Beeker and Geoffrey Conrad, director of IUB's Mathers Museum of World Cultures, took a team of faculty and graduate students to the Dominican Republic to explore intriguing magnetometer anomalies the IU scientists had discovered 10 years ago. The readings suggest large objects buried under silt and mud, and within coral colonies. The readings indicate also that the objects are scattered -- similar to how a shipwreck, or several for that matter, would appear -- in a 75-square-meter area......... Posted by: William Permalink Source Evolutionary Origin Of Fins, Limbs
Evolutionarily speaking, the genetic instructions used to construct and position our limbs were being perfected more than half a billion years ago in fishes, not along the sides of the body where the fins that preceded human arms and legs sprouted, but at the midline that runs along the backbone and belly. This midline -- think of the dorsal, tail and anal fins of a fish - is where the genetic template to produce fins originated, about 100 million years before paired fins evolved and about 200 million years before paired fins evolved into limbs, according to University of Florida genetics researchers. The findings, published online today in the journal Nature, also provide insight into the evolutionary history of genes involved in human birth defects. "Given that paired fins made their evolutionary debut at a particular location on the sides of the body, intuitively one would think the genetic tools for fin development would be brought together in that place," said developmental biologist Martin Cohn, Ph.D., an associate professor with the UF departments of zoology and anatomy and cell biology and a member of the UF Genetics Institute. "We've discovered that the genetic circuitry for building limbs first appeared in an entirely different place - the midline of the animal"......... Posted by: Ashley Permalink Source Vanishing Species
Image courtesy of Rita Sklar
The artist writes: In my recent work, I explore the dimensionality - emotional, perceptive and symbolic - of vanishing species and traditions. Wildlife and people are reverently depicted, using maps in unique ways to convey the importance of place. These paintings signal the fundamental dichotomy of the beauty and value of wildlife and the longing for resolution of that which is threatening them. My paintings reflect a balance between the reality of representational shapes and forms juxtaposed with abstract backgrounds. The addition of maps weaves a distinctive tapestry that adds complexity and texture. My affection for wildlife often reveals, at the same time, the violence and the tenderness of our times. I search for new ways to express the singularity and the diversity of our fragile world. About the Artist Sklar's recent body of "Vanishing Species" works builds on her ongoing exploration of landscapes and wildlife, mainly using watercolors. She took up art seriously only 11 years ago, attending workshops throughout the Bay Area and training with a private watercolor master in Madrid. She draws inspiration from her extensive travels to such wildlife-rich places as Peru, the Galapagos (Ecuador) and most recently, Namibia in Southern Africa. An avid birdwatcher, Sklar often has to go no farther than the Bay Area's own backyard - its Bay and many preserves and natural areas - to find material for her paintings......... Posted by: Ashley Permalink Source Ice Sheets Drive Atmospheric Carbon Dioxide Levels
It all seemed so clean and simple. And indeed the hypothesis was partially confirmed in the 1970s from marine sediment records extending through 2.75 million years of northern hemisphere ice-age cycles. As Milankovitch predicted, ice grew and melted at cycles of 23,000 and 41,000 years. But two observations were unexpected: from 2.75 until 0.9 million years ago, the ice sheets grew and melted almost entirely at the 41,000-year cycle. Since then, an oscillation near 100,000 years has dominated. This knocked Milankovitch's theory for a loop. Researchers have since turned to changes in atmospheric carbon dioxide as a possible explanation. Carbon dioxide concentrations can be measured in ancient air bubbles preserved in sequences of cores drilled into the Antarctic ice sheet. Because some changes in carbon dioxide have been found to occur slightly before changes in ice volume, the prevailing interpretation has been that carbon dioxide is an additional independent 'driver' of the size of ice sheets, along with solar radiation......... Posted by: William Permalink Source Life on Earth More Than 3.8 Billion Years Ago
Rocks on Greenland’s Akilia Island
Craig E. Manning, lead author of the new study and a professor of geology and geochemistry in the UCLA Department of Earth and Space Sciences, painstakingly mapped an area on Akilia Island in West Greenland where ancient rocks were discovered that may preserve carbon-isotope evidence for life at the time of their formation. Manning and his co-authors-T. Mark Harrison, a UCLA professor of geochemistry, director of UCLA's Institute of Geophysics and Planetary Physics, and University Professor at the Australian National University; and Stephen J. Mojzsis, assistant professor of geological sciences at the University of Colorado, Boulder-conducted new geologic and geochemical analysis on these rocks. Their findings will be published in the new issue of the American Journal of Science. Harrison and Mojzsis were co-authors on the Nov. 7, 1996, study in Nature. "This paper shows, with far greater confidence than we ever had before, that these rocks are older than 3.8 billion years," said Manning, who has conducted extensive research in Greenland. "We have shown that the rocks are appropriate for hosting life......... Posted by: William Permalink Source Shared ancestor to humans
"This intriguing finding brings us closer to understanding the point at which the building blocks of language appeared on the evolutionary timeline," says James F. Battey, Jr., M.D., Ph.D., director of the NIDCD. "While the fossil record cannot answer this question for us, we can turn to the here and now through brain imaging of living non-human primates for a glimpse into how language, or at least the neural circuitry mandatory for language, came to be."........ Posted by: William Permalink Source Large Dinosaurs Were Extremely Hot In Their Day
One of the larger animals, a behemoth called Sauroposeidon proteles, weighed close to 120,000 pounds as an adult. Now, a new study led by the University of Florida suggests it may have had a body temperature close to 48 degrees Celsius. That is a 118-degree Fahrenheit normal temperature, about as hot as most living creatures can get before the proteins in their bodies actually begin to break down. In fact, the size of the largest dinosaurs may ultimately have been limited by their body temperatures, as per a team of researchers from the UF Genetics Institute, the National Center for Ecological Analysis and Synthesis in Santa Barbara and the University of New Mexico writing this week in the online journal PLoS Biology. "One of the first things to strike me about our results was that larger dinosaurs, for their size, were much more active than contemporary reptiles," said Andrew Allen, a researcher with the NCEAS. "If these animals functioned at temperatures of 35 or 40 degrees centigrade, it suggests that they operated at a rate more like today's mammals and birds. While the largest dinosaurs may not have been running around as fast as in 'Jurassic Park,' they certainly were very active given their extreme size"......... Posted by: William Permalink Source Egyptian Mummy
The findings, together with the mummy fragments and a clay facial reconstruction are now ready to be handed back to the East Sussex school and will form part of a science project for future generations of pupils. "We have found out quite a lot about the historical background of the mummy and there have been detailed studies on the bones and teeth," said Professor Rosalie David, a world-renowned Egyptology expert and head of the centre. "We have also made a three-dimensional, facial reconstruction of the mummy and will present this with our findings to the teachers and pupils today". Uplands College in Wadhurst was given the mummy by the late Dr Dick Kittermaster, a pathologist at St Thomas's Hospital in London. Dr Kittermaster had been asked to investigate the history of the body by a museum in Cardiff in the late 1960s with help from experts at the British Museum. What they discovered was that the remains did not match the coffin it had been found in. Inscriptions on the coffin suggested the mummy was a 30-year-old male, who had been a royal carpenter around 700 BC. But what the team found was that the remains were, in fact, those of a woman......... Posted by: William Permalink Source Age Distribution Of Non-avian Dinosaur Population
Did these animals show survival patterns akin to extant living dinosaurs, the birds, as did like their crocodilian cousins? Or, did they mirror that of more distantly related dinosaurs that lived in a similar environment? A pile of bones from the North American tyrannosaur Albertosaurus sarcophagus may hold the answer. These animals "showed exceptional survivorship once they passed the hatchling stage," said Gregory Erickson of Florida State University, co-author of a paper reporting the results in this week's issue of the journal Science. "Factors such as predation and [timing of] entrance into the breeding population may have influenced survivorship," the scientists say. Such patterns are common today in wild populations of long-lived birds and mammals. Why increased survivorship as juveniles? "In living populations it occurs because animals reach threshold sizes, and predation pressures decrease," said Erickson. "By age two, most tyrannosaurs were as large or larger than nearly all other predators in their realm." "Because most species of non-avian dinosaurs are known from just one or a few specimens, very little is understood about the population biology of these animals," said Richard Lane, program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which funded the research."We now have a breakthrough in unraveling these dinosaurs' life cycles."........ Posted by: William Permalink Source |
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