Catálogo de publicaciones - revistas

<jats:title>Overcoming the limits of the microscope</jats:title> <jats:p> The resolution of a light microscope is limited. Physicists have long since worked out what these limits are and which parameters determine the spatial resolution. Many groups have nevertheless made numerous attempts to overcome these resolution limits. Rather than improving the power and quality of the microscope, Chen <jats:italic>et al.</jats:italic> instead expanded the biological specimens under study (see the Perspective by Dodt). They introduced a polymer gel into fixed cells and tissues and chemically induced swelling of the polymer by almost two orders of magnitude. They could then produce much higher-resolution images of their samples, which included the mouse hippocampus. </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="6221" page="543" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1260088">543</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6221" page="474" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa5084">474</jats:related-article> </jats:p>

<jats:title>Switching transcription and replication</jats:title> <jats:p> Because mitochondrial DNA is circular, the transcription and replication machinery might be expected to collide. A single mitochondrial RNA polymerase (mtRNAP) transcribes the mitochondrial DNA and also generates primers for replication. Agaronyan <jats:italic>et al.</jats:italic> now show that transcription and replication are kept separate in human mitochondria, with the mitochondrial transcription elongation factor TEFM serving as a key player in the switch. In the absence of TEFM, mtRNAP terminates downstream from the promoter, forming primers to promote replication. In the presence of TEFM, the primers are not formed, and the overall processivity of mtRNAP elongation complexes is enhanced, promoting genome transcription. These mutually exclusive mechanisms allow the processes to proceed independently as needed by the cell. </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="6221" page="548" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa0986">548</jats:related-article> </jats:p>

<jats:title>Structural clues to protein function</jats:title> <jats:p> Translocator protein (TSPO) is a mitochondrial membrane protein thought to transport cholesterol and porphyrins. Its detailed function remains unclear, but interest in it is high because TSPO is involved in a variety of human diseases. Two papers now present crystal structures of bacterial TSPOs. Li <jats:italic>et al.</jats:italic> show that a mutant that mimics a human single polymorphism associated with psychiatric disorders has structural changes in a region implicated in cholesterol binding. Guo <jats:italic>et al.</jats:italic> suggest that TSPO may be more than a transporter. They show how it catalyzes the degradation of porphyrins, a function that could be important in protection against oxidative stress. </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="6221" page="555" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1260590">555</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6221" page="551" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa1534">551</jats:related-article> </jats:p>

<jats:title>Structural clues to protein function</jats:title> <jats:p> Translocator protein (TSPO) is a mitochondrial membrane protein thought to transport cholesterol and porphyrins. Its detailed function remains unclear, but interest in it is high because TSPO is involved in a variety of human diseases. Two papers now present crystal structures of bacterial TSPOs. Li <jats:italic>et al.</jats:italic> show that a mutant that mimics a human single polymorphism associated with psychiatric disorders has structural changes in a region implicated in cholesterol binding. Guo <jats:italic>et al.</jats:italic> suggest that TSPO may be more than a transporter. They show how it catalyzes the degradation of porphyrins, a function that could be important in protection against oxidative stress. </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="6221" page="555" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.1260590">555</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6221" page="551" related-article-type="in-this-issue" vol="347" xlink:href="10.1126/science.aaa1534">551</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: Mathematicians and the NSA, and a roundup of daily news stories.</jats:p>

<jats:p>Managing an academic research group means keeping an eye on the big picture—long-term goals, funding agency priorities, and a publication plan. Faculty members are also charged with training students and postdoctoral fellows. To meet these dual demands, principal investigators must match people to projects in way that gets the group to its goals while encouraging its members to mature as scientists. Faculty members don't usually get formal training in research program management, but that might be changing.</jats:p>