Catálogo de publicaciones - revistas

<jats:title>Supplying power: Right time, right place</jats:title> <jats:p> Cell membranes are very flexible and easily molded to shape; however, to physically pinch off a membrane vesicle from a membrane tube still requires power. A type of molecular machine known as dynamin is involved in this sort of membrane remodeling. Dynamins use guanosine triphosphate (GTP) rather than the more commonly used cellular energy source adenosine triphosphate to work. Boissan <jats:italic>et al.</jats:italic> now show that two separate dynamins found in the cytoplasm or the mitochondria both use the same sort of enzyme—nucleoside diphosphate kinases—to provide GTP at just the right time and the right place to power membrane fission. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6191" page="1510" related-article-type="in-this-issue" vol="344" xlink:href="10.1126/science.1253768">1510</jats:related-article> </jats:p>

<jats:title>How hawkmoths sniff out a flower</jats:title> <jats:p> Pollinators such as butterflies and bees are the true targets of the flower odors we love so much. Though we might imagine insects “following their noses,” the wealth of odors in the real world can drown out the smell of a flower, making it hard to find. Riffel <jats:italic>et al.</jats:italic> found that hawkmoths find angel's trumpets by creating a neuronal picture within their antennal lobe, the part of the moth brain that receives olfactory signals from the antennae (see the Perspective by Szyszka). The picture represents both the flower and the background odors. Finding a flower involves a complex reading of both background and target odors, and changes in the background odors—including human pollutants—can hinder the process. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6191" page="1515" related-article-type="in-this-issue" vol="344" xlink:href="10.1126/science.1251041">1515</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6191" page="1454" related-article-type="in-this-issue" vol="344" xlink:href="10.1126/science.1255748">1454</jats:related-article> </jats:p>

<jats:title>Clouding evolution's crystal ball</jats:title> <jats:p> Because of a sort of mutation buffering process, different starting mutations can tend to end up with similar overall affects on an organism's fitness. Kryazhimskiy <jats:italic>et al.</jats:italic> evolved lines of yeast, each originating from distinct single genotypes, under the same selective regimen. A subset of clones from these adapted populations was subjected to fitness assays and sequenced. Populations with lower initial fitness, adapted more rapidly than populations with higher initial fitness, so that in the end the fitness levels were similar. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6191" page="1519" related-article-type="in-this-issue" vol="344" xlink:href="10.1126/science.1250939">1519</jats:related-article> </jats:p>

<jats:title>Only one way to make an electric organ?</jats:title> <jats:p> Electric fish have independently evolved electric organs that help them to communicate, navigate, hunt, and defend themselves. Gallant <jats:italic>et al.</jats:italic> analyzed the genome of the electric eel and the genes expressed in two other distantly related electric fish. The same genes were recruited within the different species to make evolutionarily new structures that function similarly. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6191" page="1522" related-article-type="in-this-issue" vol="344" xlink:href="10.1126/science.1254432">1522</jats:related-article> </jats:p>

<jats:p>A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.</jats:p>

<jats:p>On this week's show: Following the pollen path and a roundup of stories from our daily news site.</jats:p>

<jats:sec> <jats:title>Background</jats:title> <jats:p> Until recently, the evolution of the genus <jats:italic>Homo</jats:italic> has been interpreted in the context of the onset of African aridity and the expansion of open grasslands. <jats:italic>Homo erectus</jats:italic> was considered to be a bona fide member of the genus <jats:italic>Homo</jats:italic> , but opinions diverged on the generic status of earlier, more fragmentary fossils traditionally attributed to <jats:italic>Homo habilis</jats:italic> and <jats:italic>Homo rudolfensis</jats:italic> . Arguments about generic status of these taxa rested on inferred similarities and differences in adaptive plateau. However, there was near-universal agreement that the open-country suite of features inferred for <jats:italic>Homo erectus</jats:italic> had evolved together and provided the adaptations for dispersal beyond Africa. These features foreshadowed those of more recent <jats:italic>Homo sapiens</jats:italic> and included large, linear bodies, elongated legs, large brain sizes, reduced sexual dimorphism, increased carnivory, and unique life history traits (e.g., extended ontogeny and longevity) as well as toolmaking and increased social cooperation. </jats:p> </jats:sec> <jats:sec> <jats:title>Advances</jats:title> <jats:p> Over the past decade, new fossil discoveries and new lines of interpretation have substantially altered this interpretation. New environmental data sets suggest that <jats:italic>Homo</jats:italic> evolved against a background of long periods of habitat unpredictability that were superimposed on the underlying aridity trend. New fossils support the presence of multiple groups of early <jats:italic>Homo</jats:italic> that overlap in body, brain, and tooth size and challenge the traditional interpretation of <jats:italic>H. habilis</jats:italic> and <jats:italic>H. rudolfensis</jats:italic> as representing small and large morphs, respectively. Because of a fragmentary and distorted type specimen for <jats:italic>H. habilis</jats:italic> two informal morphs are proposed, the 1813 group and the 1470 group, that are distinguished on the basis of facial anatomy but do not contain the same constituent fossils as the more formally designated species of early <jats:italic>Homo</jats:italic> . Furthermore, traits once thought to define early <jats:italic>Homo</jats:italic> , particularly <jats:italic>H. erectus</jats:italic> , did not arise as a single package. Some features once considered characteristic of <jats:italic>Homo</jats:italic> are found in <jats:italic>Australopithecus</jats:italic> (e.g., long hind limbs), whereas others do not occur until much later in time (e.g., narrow pelves and extended ontogeny). When integrated with our understanding of the biology of living humans and other mammals, the fossil and archaeological record of early <jats:italic>Homo</jats:italic> suggests that key factors to the success and expansion of the genus rested on dietary flexibility in unpredictable environments, which, along with cooperative breeding and flexibility in development, allowed range expansion and reduced mortality risks. </jats:p> </jats:sec> <jats:sec> <jats:title>Outlook</jats:title> <jats:p> Although more fossils and archaeological finds will continue to enhance our understanding of the evolution of early <jats:italic>Homo</jats:italic> , the comparative biology of mammals (including humans) will continue to provide valuable frameworks for the interpretation of existing material. This comparative context enables us to formulate and test robust models of the relationships between energetics, life history, brain and body size, diet, mortality, and resource variability and thereby yield a deeper understanding of human evolution. </jats:p> </jats:sec>

<jats:p> Numbers. Lots and lots of numbers. It is hard to find a paper published in <jats:italic>Science</jats:italic> or any other journal that is not full of numbers. Interpretation of those numbers provides the basis for the conclusions, as well as an assessment of the confidence in those conclusions. But unfortunately, there have been far too many cases where the quantitative analysis of those numbers has been flawed, causing doubt about the authors' interpretation and uncertainty about the result. Furthermore, it is not realistic to expect that a technical reviewer, chosen for her or his expertise in the topical subject matter or experimental protocol, will also be an expert in data analysis. For that reason, with much help from the American Statistical Association, <jats:italic>Science</jats:italic> has established, effective 1 July 2014, a Statistical Board of Reviewing Editors (SBoRE), consisting of experts in various aspects of statistics and data analysis, to provide better oversight of the interpretation of observational data. </jats:p>

<jats:p>A roundup of weekly science policy and related news.</jats:p>