Catálogo de publicaciones - revistas

<jats:p>Modeling suggests that volcanic output and microorganisms created a distinctive profile of sulfur isotopes on early Earth.</jats:p>

<jats:title>Quake Control</jats:title> <jats:p> Large earthquakes occur at the margins of two colliding plates, where one plate subducts beneath the other at a shallow angle. These megathrust earthquakes often cause destructive tsunamis owing to the displacement of large volumes of water at the fault along the plate boundary. Two related studies of the seismic structure of subduction zones attempt to reveal the underlying mechanisms of megathrust earthquakes (see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5988" page="152" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1192223">Wang</jats:related-article> </jats:bold> ). <jats:bold> Kimura <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5988" page="210" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1187115">210</jats:related-article> ) compared seismic reflection images and microearthquake locations at the Philippine Sea plate where it subducts obliquely beneath Japan. The locations of repeating microearthquakes correspond to active transfer of material from the subducting plate to the continent—a process only previously assumed from exhumed metamorphic rocks. <jats:bold> Dean <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5988" page="207" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1189373">207</jats:related-article> ) observe an expansive structure in the sea-floor sediment near the location of the 2004 and 2005 Sumatra earthquakes in Indonesia that suggests sediment properties may influence the magnitude of megathrust ruptures and their subsequent tsunamis. </jats:p>

<jats:title>Quake Control</jats:title> <jats:p> Large earthquakes occur at the margins of two colliding plates, where one plate subducts beneath the other at a shallow angle. These megathrust earthquakes often cause destructive tsunamis owing to the displacement of large volumes of water at the fault along the plate boundary. Two related studies of the seismic structure of subduction zones attempt to reveal the underlying mechanisms of megathrust earthquakes (see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5988" page="152" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1192223">Wang</jats:related-article> </jats:bold> ). <jats:bold> Kimura <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5988" page="210" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1187115">210</jats:related-article> ) compared seismic reflection images and microearthquake locations at the Philippine Sea plate where it subducts obliquely beneath Japan. The locations of repeating microearthquakes correspond to active transfer of material from the subducting plate to the continent—a process only previously assumed from exhumed metamorphic rocks. <jats:bold> Dean <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5988" page="207" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1189373">207</jats:related-article> ) observe an expansive structure in the sea-floor sediment near the location of the 2004 and 2005 Sumatra earthquakes in Indonesia that suggests sediment properties may influence the magnitude of megathrust ruptures and their subsequent tsunamis. </jats:p>

<jats:title>Offsetting the Cost of Parasitism</jats:title> <jats:p> Fruit flies, like most animals, are vulnerable to infection by a range of organisms, which, in co-infections, can interact with sometimes surprising effects. <jats:bold> Jaenike <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5988" page="212" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1188235">212</jats:related-article> ) discovered that a species of <jats:italic>Spiroplasma</jats:italic> bacterium that is sometimes found in flies, and that is transmitted from mother to offspring, protects its host from the effects of a nematode worm parasite, <jats:italic>Howardula aoronymphium</jats:italic> . The worm sterilizes the female flies and shortens their lives, but when flies were experimentally infected with <jats:italic>Spiroplasma</jats:italic> , their fertility was rescued. Similarly, in wild populations of fruit flies infected with worms, those also infected with <jats:italic>Spiroplasma</jats:italic> had more eggs in their ovaries. The bacterium inhibits the growth of the adult female worms, but such is the advantage of this bacterial infection in offsetting the burden of nematodes on reproductive fitness, <jats:italic>Spiroplasma</jats:italic> appears to be spreading rapidly through populations of fruit flies in North America. </jats:p>

<jats:title>Getting Gametes Together</jats:title> <jats:p> Despite decades of research, the molecular basis of sperm-egg recognition in mammals remains unresolved. Models in which a glycan ligand in the zona pellucida (ZP) surrounding ovulated eggs binds to a sperm surface receptor have been widely embraced. A more recent model proposes that the cleavage status of a ZP protein, ZP2, renders the structure of the zona matrix either permissive or nonpermissive for sperm binding. <jats:bold> Gahlay <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5988" page="216" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1188178">216</jats:related-article> ) tested predictions of each model by replacing endogenous zona proteins with either a mutant form of ZP2 that could not be cleaved or of ZP3 that lacked O glycan attachment sites. Sperm-egg recognition depended on the cleavage status of ZP2 rather than on glycan ligands released following fertilization. </jats:p>

<jats:title>Righting Repair Pathways</jats:title> <jats:p> The genetic disease Fanconi anemia (FA) results from mutations in a series of genes involved in a DNA repair pathway that helps process the damage caused by erroneous chemical cross-links between the two strands of the DNA double helix. The double-stranded breaks in DNA that arise from such cross-links can be repaired in an error-free manner or through an error-prone repair pathway. <jats:bold> Pace <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5988" page="219" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1192277">219</jats:related-article> , published online 10 June) show that the FA pathway can drive repair through the error-free pathway. The FA <jats:italic>FANCC</jats:italic> gene shows a genetic interaction with a component of the error-prone repair pathway, Ku70, inhibiting its action and thereby promoting the error-free pathway. </jats:p>

<jats:title>Going Multicellular</jats:title> <jats:p> The volvocine algae include both the unicellular <jats:italic>Chlamydomonas</jats:italic> and the multicellular <jats:italic>Volvox</jats:italic> , which diverged from one another 50 to 200 million years ago. <jats:bold> Prochnik <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5988" page="223" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1188800">223</jats:related-article> ) compared the <jats:italic>Volvox</jats:italic> genome with that of <jats:italic>Chlamydomonas</jats:italic> to identify any genomic innovations that might have been associated with the transition to multicellularity. Size changes were observed in several protein families in <jats:italic>Volvox</jats:italic> , but, overall, the <jats:italic>Volvox</jats:italic> genome and predicted proteome were highly similar to those of <jats:italic>Chlamydomonas</jats:italic> . Thus, biological complexity can arise without major changes in genome content or protein domains. </jats:p>

<jats:p>Relative rates of nucleotide substitution between host and parasite cytochrome b set the molecular clock for malaria.</jats:p>

<jats:title>Correcting a Liver Problem</jats:title> <jats:p> The classical form of α <jats:sub>1</jats:sub> -antitrypsin (AT) deficiency is caused by a point mutation that alters the folding and causes intracellular aggregation of AT—an abundant liver-derived plasma glycoprotein. AT deficiency is the most common genetic cause of liver disease in childhood and can also lead to cirrhosis and/or hepatocellular carcinoma in adulthood. Carbamazepine is a drug known to be well tolerated in humans that enhances the intracellular degradation process known as autophagy. Now, <jats:bold> Hidvegi <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5988" page="229" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1190354">229</jats:related-article> , published online June 3; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5988" page="154" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1192681">Sifers</jats:related-article> </jats:bold> ) show that carbamazepine can reduce the severity of liver disease in a mouse model of AT deficiency by enhancing the degradation of misfolded accumulated AT. </jats:p>

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