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Hudjashov G.,Evolutionary Biology Group
PloS one | Year: 2013

Global variation in skin pigmentation is one of the most striking examples of environmental adaptation in humans. More than two hundred loci have been identified as candidate genes in model organisms and a few tens of these have been found to be significantly associated with human skin pigmentation in genome-wide association studies. However, the evolutionary history of different pigmentation genes is rather complex: some loci have been subjected to strong positive selection, while others evolved under the relaxation of functional constraints in low UV environment. Here we report the results of a global study of the human tyrosinase gene, which is one of the key enzymes in melanin production, to assess the role of its variation in the evolution of skin pigmentation differences among human populations. We observe a higher rate of non-synonymous polymorphisms in the European sample consistent with the relaxation of selective constraints. A similar pattern was previously observed in the MC1R gene and concurs with UV radiation-driven model of skin color evolution by which mutations leading to lower melanin levels and decreased photoprotection are subject to purifying selection at low latitudes while being tolerated or even favored at higher latitudes because they facilitate UV-dependent vitamin D production. Our coalescent date estimates suggest that the non-synonymous variants, which are frequent in Europe and North Africa, are recent and have emerged after the separation of East and West Eurasian populations. Source


Kivi G.,Icosagen Cell Factory OU | Kivi G.,University of Tartu | Teesalu K.,Icosagen Cell Factory OU | Parik J.,Evolutionary Biology Group | And 6 more authors.
BMC Biotechnology | Year: 2016

Background: The production of recombinant monoclonal antibodies in mammalian cell culture is of high priority in research and medical fields. A critical step in this process is the isolation of the antigen-binding domain sequences of antibodies possessing the desired properties. Many different techniques have been described to achieve this goal, but all have shortcomings; most techniques have problems with robustness, are time-consuming and costly, or have complications in the transfer from isolation to production phase. Here, we report a novel HybriFree technology for the development of monoclonal antibodies from different species that is robust, rapid, inexpensive and flexible and can be used for the subsequent production of antibodies in mammalian cell factories. Results: HybriFree technology is illustrated herein via detailed examples of isolating mouse, rabbit and chicken monoclonal antibody sequences from immunized animals. Starting from crude spleen samples, antigen capturing of specific B-cells is performed initially. cDNA of antibody variable domains is amplified from the captured cells and used a source material for simple and rapid restriction/ligation free cloning of expression vector library in order to produce scFv-Fc or intact IgG antibodies. The vectors can be directly used for screening purposes as well as for the subsequent production of the developed monoclonal antibodies in mammalian cell culture. The antibodies isolated by the method have been shown to be functional in different immunoassays, including ELISA, immunofluorescence and Western blot. In addition, we demonstrate that by using a modified method including a negative selection step, we can isolate specific antibodies targeting the desired epitope and eliminate antibodies directed to undesired off-targets. Conclusions: HybriFree can be used for the reliable development of monoclonal antibodies and their subsequent production in mammalian cells. This simple protocol requires neither the culturing of B-cells nor single-cell manipulations, and only standard molecular biology laboratory equipment is needed. In principle, the method is applicable to any species for which antibody cDNA sequence information is available. © 2016 Kivi et al. Source


News Article
Site: http://news.yahoo.com/science/

A life reconstruction of Morelladon is shown in this illustration provided by Carlos de Miguel Chaves. Scientists on December 16, 2015 announced the discovery near the town of Morella in Spain's Castellon Province of the fossil remains of a medium-sized dinosaur they named Morelladon, a four-legged herbivore that measured 6 meters (20 feet) long. Protruding from its back was a series of bony spines that formed the sail-like structure that stood about two feet (60 cm) tall. REUTERS/Carlos de Miguel Chaves/Handout via Reuters More WASHINGTON (Reuters) - Along a lush river delta in what is now northeastern Spain, a herd of dinosaurs munched on ferns and conifers similar to modern-day cypresses 125 million years ago. These creatures stood out from the others in this Cretaceous Period landscape by virtue of the unusual sail-like structure on their backs, and experts today can only hypothesize about its function. Scientists announced on Wednesday the discovery near the town of Morella in Spain's Castellón Province of the fossil remains of a medium-sized dinosaur they named Morelladon, a four-legged herbivore that measured 6 metres (20 feet) long. Protruding from its back was a series of bony spines that formed the sail-like structure that stood about 2 feet (60 cm) tall. "The sail could help in heat exchange - thermoregulation - focused on releasing excess body heat into the environment, like the ears of the modern-day elephants, or as a storage place for fat to be used during periods of low food supply," said paleontologist Fernando Escaso of the National University of Distance Education's Evolutionary Biology Group in Spain. The structure also could have served a display role in attracting mates, Escaso added. Escaso noted that sail-like structures appeared periodically in the evolutionary history of vertebrates, often in animal groups not closely related to one another. Another plant-eating dinosaur called Ouranosaurus with similarities to Morelladon lived about the same time in Africa. The biggest sail-backed creature was Spinosaurus, which lived a semi-aquatic lifestyle 95 million years ago in Africa. At 50 feet long (15 metres) and 7 tons, it was the biggest dinosaur predator on record, larger even than Tyrannosaurus rex. Millions of years before the rise of the dinosaurs, there were other sail-backed creatures including the carnivorous reptile Arizonasaurus, the amphibian Platyhystrix and the distant mammal relatives Dimetrodon and Edaphosaurus. Morelladon is known from a partial skeleton including the spines, other vertebrae, pelvic bones, a thigh bone and teeth. Northeastern Spain during Morelladon's time alternated between wet and dry periods, with strong temperature variations ranging from 40 degrees Fahrenheit (4 Celsius) to about 104 F (40 C). Escaso said the main predator in the area was Baryonyx, a relative of Spinosaurus, and there were other plant-eating dinosaurs around as well as crocodilians and the flying reptiles called pterosaurs. The research was published in the journal PLOS ONE.


News Article
Site: http://news.yahoo.com/science/

A life reconstruction of Morelladon is shown in this illustration provided by Carlos de Miguel Chaves. Scientists on December 16, 2015 announced the discovery near the town of Morella in Spain's Castellon Province of the fossil remains of a medium-sized dinosaur they named Morelladon, a four-legged herbivore that measured 6 meters (20 feet) long. Protruding from its back was a series of bony spines that formed the sail-like structure that stood about two feet (60 cm) tall. REUTERS/Carlos de Miguel Chaves/Handout via Reuters More WASHINGTON (Reuters) - Along a lush river delta in what is now northeastern Spain, a herd of dinosaurs munched on ferns and conifers similar to modern-day cypresses 125 million years ago. These creatures stood out from the others in this Cretaceous Period landscape by virtue of the unusual sail-like structure on their backs, and experts today can only hypothesize about its function. Scientists announced on Wednesday the discovery near the town of Morella in Spain's Castellón Province of the fossil remains of a medium-sized dinosaur they named Morelladon, a four-legged herbivore that measured 6 meters (20 feet) long. Protruding from its back was a series of bony spines that formed the sail-like structure that stood about 2 feet (60 cm) tall. "The sail could help in heat exchange - thermoregulation - focused on releasing excess body heat into the environment, like the ears of the modern-day elephants, or as a storage place for fat to be used during periods of low food supply," said paleontologist Fernando Escaso of the National University of Distance Education's Evolutionary Biology Group in Spain. The structure also could have served a display role in attracting mates, Escaso added. Escaso noted that sail-like structures appeared periodically in the evolutionary history of vertebrates, often in animal groups not closely related to one another. Another plant-eating dinosaur called Ouranosaurus with similarities to Morelladon lived about the same time in Africa. The biggest sail-backed creature was Spinosaurus, which lived a semi-aquatic lifestyle 95 million years ago in Africa. At 50 feet long (15 metres) and 7 tons, it was the biggest dinosaur predator on record, larger even than Tyrannosaurus rex. Millions of years before the rise of the dinosaurs, there were other sail-backed creatures including the carnivorous reptile Arizonasaurus, the amphibian Platyhystrix and the distant mammal relatives Dimetrodon and Edaphosaurus. Morelladon is known from a partial skeleton including the spines, other vertebrae, pelvic bones, a thigh bone and teeth. Northeastern Spain during Morelladon's time alternated between wet and dry periods, with strong temperature variations ranging from 40 degrees Fahrenheit (4 Celsius) to about 104 F (40 C). Escaso said the main predator in the area was Baryonyx, a relative of Spinosaurus, and there were other plant-eating dinosaurs around as well as crocodilians and the flying reptiles called pterosaurs. The research was published in the journal PLOS ONE.


Raghavan M.,Copenhagen University | Skoglund P.,Uppsala University | Graf K.E.,Texas A&M University | Metspalu M.,Evolutionary Biology Group | And 36 more authors.
Nature | Year: 2014

The origins of the First Americans remain contentious. Although Native Americans seem to be genetically most closely related to east Asians, there is no consensus with regard to which specific Old World populations they are closest to. Here we sequence the draft genome of an approximately 24,000-year-old individual (MA-1), from Mal'ta in south-central Siberia, to an average depth of 1×. To our knowledge this is the oldest anatomically modern human genome reported to date. The MA-1 mitochondrial genome belongs to haplogroup U, which has also been found at high frequency among Upper Palaeolithic and Mesolithic European hunter-gatherers, and the Y chromosome of MA-1 is basal to modern-day western Eurasians and near the root of most Native American lineages. Similarly, we find autosomal evidence that MA-1 is basal to modern-day western Eurasians and genetically closely related to modern-day Native Americans, with no close affinity to east Asians. This suggests that populations related to contemporary western Eurasians had a more north-easterly distribution 24,000 years ago than commonly thought. Furthermore, we estimate that 14 to 38% of Native American ancestry may originate through gene flow from this ancient population. This is likely to have occurred after the divergence of Native American ancestors from east Asian ancestors, but before the diversification of Native American populations in the New World. Gene flow from the MA-1 lineage into Native American ancestors could explain why several crania from the First Americans have been reported as bearing morphological characteristics that do not resemble those of east Asians. Sequencing of another south-central Siberian, Afontova Gora-2 dating to approximately 17,000 years ago, revealed similar autosomal genetic signatures as MA-1, suggesting that the region was continuously occupied by humans throughout the Last Glacial Maximum. Our findings reveal that western Eurasian genetic signatures in modern-day Native Americans derive not only from post-Columbian admixture, as commonly thought, but also from a mixed ancestry of the First Americans. © 2014 Macmillan Publishers Limited. Source

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