Catálogo de publicaciones - revistas

<jats:title>All the Smells of the World</jats:title> <jats:p> How many odorant stimuli can a normal human being discriminate? During psychophysical tests of odor mixture discrimination, <jats:bold> Bushdid <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="6177" page="1370" related-article-type="in-this-issue" vol="343" xlink:href="10.1126/science.1249168">1370</jats:related-article> ) were surprised to find that humans can discriminate among more than a trillion different smells. Because the authors reduced the complexity by investigating only mixtures of 10, 20, or 30 components drawn from a collection of 128 odorous molecules, this astonishingly large number is probably the lower limit of the potential number of olfactory stimuli that humans can distinguish. </jats:p>

<jats:title>Real Network Control</jats:title> <jats:p> Understanding how complex networks are controlled has implications for a variety of real-world networks, from traffic safety to transcriptional control. <jats:bold>Ruths and Ruths</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6177" page="1373" related-article-type="in-this-issue" vol="343" xlink:href="10.1126/science.1242063">1373</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6177" page="1325" related-article-type="in-this-issue" vol="343" xlink:href="10.1126/science.1251746">Onnela</jats:related-article> </jats:bold> ) have developed a theoretical framework for analyzing individual controls within networks based on numbers of sources and sinks for information flow. By this method, the number of controls required by a network can be predicted and direct comparisons for the basis for control across networks of differing size, structure, and function can be made. Although three broad classes of real networks were observed, current, established random models of networks were insufficient to model their control structures. </jats:p>

<jats:title>Cytologically Informative Fossils</jats:title> <jats:p> Fossilization processes tend to destroy fine-cell structure but, exceptionally, <jats:bold> Bomfleur <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="6177" page="1376" related-article-type="in-this-issue" vol="343" xlink:href="10.1126/science.1249884">1376</jats:related-article> ) have found examples of fossil ferns from the Jurassic in which subcellular structures, including organelles such as nuclei and chromosomes, are well-preserved. Comparative and quantative analyses show that these cells closely resemble the fossil nuclei of extant cinnamon ferns, <jats:italic>Osmundastrum cinnamomea</jats:italic> , which indicates that this group of ferns has remained virtually unchanged for 180 million years. </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: human odor discrimination pegged at one trillion odors and a roundup from our daily news site.</jats:p>

<jats:title>Gut Immune Tolerance</jats:title> <jats:p> With the constant assault of food antigens and its billions of resident microbes, the gut is an important site of immune tolerance. By studying specific intestinal immune cell populations in genetically modified mice, <jats:bold> Mortha <jats:italic>et al.</jats:italic> </jats:bold> ( <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" related-article-type="in-this-issue" xlink:href="10.1126/science.1249288">10.1126/science.1249288</jats:related-article> , published online 13 March; see the Perspective by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6178" page="1439" related-article-type="in-this-issue" vol="343" xlink:href="10.1126/science.1252785"> <jats:bold>Aychek and Jung</jats:bold> </jats:related-article> ) found that gut macrophages produce the cytokine interleukin-1 (IL-1) in response to signals derived from the microbiota. IL-1 acts on type 3 innate lymphoid cells in the intestine, which then produce the cytokine, colony-stimulating factor 2 (Csf2). Csf-2, in turn, induces myeloid cells (including dendritic cells and macrophages) to produce regulatory factors like retinoic acid and interleukin-10, which support the conversion and expansion of regulatory T cells, a population of cells known to be critical for maintaining immune tolerance in the gut. </jats:p>