dar burunlu insaymun, güney sap gözlü -iensi, juvenil ape http://www.medcezir.tumblr.com
Get flash to fully experience Pearltrees
The comprehensive characterization of homeodomain DNA-binding specificities is described for Drosophila melanogaster. The analysis of all 84 independent homeodomains from Drosophila reveals the breadth of DNA sequences that can be specified by the homeodomain. The majority of these factors can be organized into 11 different specificity groups, where the preferred recognition sequence between these groups can differ at up to four of the six core recognition positions. Analysis of the recognition motifs within these groups led to a catalog of common specificity determinants that may cooperate or compete to define the binding site preference. With these recognition principles, a homeodomain can be reengineered to create factors where its specificity is altered at the majority of recognition positions.
Abstract: The widespread use of antibiotics has markedly improved public health over the last 60 years. However, the efficacy of antibiotic treatment is rapidly decreasing as a result of the continual spread of antibiotic resistance in pathogen populations. The evolution of antibiotic resistance is an amazingly simple example of adaptation by natural selection, and there is growing interest among evolutionary biologists in using evolutionary principles to help understand and combat the spread of resistance in pathogen populations. In this article, we review recent progress in our understanding of the underlying evolutionary forces that drive antibiotic resistance. Recent work has shown that both the mechanisms of antibiotic action and resistance, as well as the treatment context in which resistance evolves, influence the evolution of resistance in predictable ways.
Photograph courtesy Russell Watkins, U.K. Department for International Development Trees shrouded in ghostly cocoons line the edges of a submerged farm field in the Pakistani village of Sindh, where 2010's massive floods drove millions of spiders and possibly other insects into the trees to spin their webs.
Ken Miller on Intelligent Design
The scientists, led by Li Jin of the Chinese Academy of Sciences in Shanghai, report in the journal Genome Research that certain disease-causing variant genes became more common in African-Americans after their ancestors reached American shores — perhaps because they conferred greater, offsetting benefits. Other gene variants have become less common, the researchers say, like the gene for sickle cell hemoglobin, which in its more common single-dose form protects against malaria. The Shanghai team suggests the gene has become less common in African-Americans because malaria is much less of a threat.
My (non)Postdoc Story: Marketing at Scientific Publisher March 26, 2013 While nearly all of us face challenges during our postdoctoral years, we often feel alone in our struggles. In this series, we hope to share encouraging and uplifting stories of how other scientists were able to turn their situation around and move forward, despite a non-ideal situation.
A cat-like animal explodes from the long grass and leaps onto an antelope. Its huge bulk drags the target to the ground and its muscled forelegs pin it down. With two long sabre-shaped canine teeth, it stabs its victim in the throat, just the once, severing its blood vessels and windpipe. Death comes quickly. The hunter could be Smilodon , a sabre-toothed cat that lived throughout North and South America, around one or two million years ago.
Güncelleme: 09:45 TSİ 02 Ocak. 2012 Pazartesi KuzeyDoğa Derneği Başkanı Doç. Dr. Çağan Şekercioğlu ve yazar Janice Wormworth tarafındankaleme alınan ve Temmuz 2011’de yayınlanan “Kanatlı Gözcüler: Kuşlar ve İklim Değişikliği” kitabı doğa tarihi, dünyanın en önemli çevre, doğal tarih ve yaban hayat kitap evi olan İngiliz Natural History Book Service tarafından 2011 yılının kitabı seçildi. Çevre, doğa tarihi ve yaban hayat konularında dünyanınen kapsamlı ve saygın yayınevi olan İngiliz Natural History Book Service, 2011yılında yayınlanmış, en ilginç, orijinal ve bilgilendirici, okuyuculara yeni bakış açıları kazandıran, eski konulara yeni yaklaşımlar getiren ve insanları daha fazla anlamaya ve araştırmaya yönelten 10 kitap listesini yayınladı.
Açık Bilim Cepyayını’nın ikincisini, evrim genetiği üzerinde çalışan Dr. Ömer Gökçümen ile yaptık. Podcast: Play in new window | Download
<img class="alignnone size-full wp-image-90752" title="guard-hair-palisade-neural-endings-cell" src="http://www.wired.com/images_blogs/wiredscience/2011/12/guard-hair-palisade-neural-endings-cell.jpg" alt="" width="660" height="540" /> A new technique for color-coding nerves involved in touch gives neuroscientists a much-needed tool for studying that mysterious sense. For nearly 250 years, the intricate detail and complexity of skin’s nervous-system wiring has thwarted attempts at understanding it. But if researchers studying skin could be imagined as technicians reverse-engineering a supercomputer’s peripherals, they’d have just traced about four lines back to the motherboard. “Of all five major senses, the skin sense is the least understood. It’s an enormous frontier, and this is a huge leap forward,” said Jeff Woodbury of the University of Wyoming, a sensory biologist who co-authored a study of nerve endings Dec. 23 in Cell .
This is a story of about how the parts of a puzzle locked into place 800 million years ago. The puzzle is an ion pump that you can find in any mushroom, mold, or yeast. I’ve reproduced a picture of it here. Fungus cells, like our own cells, have lots of little pouches inside of them for carrying out special kinds of chemical reactions. In order for those reactions to work, there have to be a lot of positively-charged protons inside the pouches. To get those protons into the pouches, ion pumps like this one force them through membranes.
Giant Galapagos Tortoises in Isabela Island, Galapagos. Adults of large subspecies can weigh over 300 kilograms (660lb) and measure 1.2 meters (4 ft) long. Although the maximum life expectancy of a wild tortoise is unknown, the average life expectancy is estimated to be 200 years.
Posted by TANN China , Evolution , Fossils , Origin of Life , Palaeontology 1:00 PM Evidence of the single-celled ancestors of animals, dating from the interval in Earth's history just before multicellular animals appeared, has been discovered in 570 million-year-old rocks from South China by researchers from the University of Bristol, the Swedish Museum of Natural History, the Paul Scherrer Institut and the Chinese Academy of Geological Sciences. All life evolved from a single-celled universal common ancestor, and at various times in Earth history, single-celled organisms threw their lot in with each other to become larger and multicellular, resulting, for instance, in the riotous diversity of animals. However, fossil evidence of these major evolutionary transitions is extremely rare.
The next time you're tempted to call some oaf a Neanderthal, you might want to take a look in the mirror. According to a new DNA study, most humans have a little Neanderthal in them—at least 1 to 4 percent of a person's genetic makeup. The study uncovered the first solid genetic evidence that "modern" humans—or Homo sapiens —interbred with their Neanderthal neighbors, who mysteriously died out about 30,000 years ago. What's more, the Neanderthal-modern human mating apparently took place in the Middle East, shortly after modern humans had left Africa , not in Europe —as has long been suspected.
Most molecules, including proteins, are too large to pass directly through membranes. Instead, large molecules are loaded into small membrane-wrapped containers called vesicles. Vesicles are constantly forming - especially at the plasma membrane, the ER, and the Golgi. Once formed, vesicles deliver their contents to destinations within or outside of the cell. A vesicle forms when the membrane bulges out and pinches off.