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<jats:title>Big Finger</jats:title> <jats:p> Alvarezsauroidea are an enigmatic group of theropods presumed to be closely related to birds, though most specimens are younger than <jats:italic>Archaeopteryx</jats:italic> . <jats:bold> Choiniere <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="571" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1182143">571</jats:related-article> ; see news story by Stone) now describe a more complete early specimen, dating to about 160 million years ago, which supports the conclusion that Alvarezsauroidea are a basal group of the clade containing both birds and their close theropod relatives. The fossil also helps to reveal the evolution of this group's peculiar forelimb, which includes one enlarged functional finger. </jats:p>

<jats:title>Sex Avoidance Strategy</jats:title> <jats:p> In metazoans, sex, as a means of reproduction, is almost universal, with popular theories suggesting that the high rate of genome mixing that sex promotes helps protect us from deleterious mutations and/or rapidly evolving parasites. Asexual organisms are both rare and often evolutionarily short-lived. If this rarity is due to failure to deal with parasites, then bdelloid rotifers, which have been abstaining from sex for millions of years, must be able to dodge the parasite bullet in some arrange-other way. <jats:bold>Wilson and Sherman</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="574" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1179252">574</jats:related-article> ; see the cover) suggest that bdelloid rotifers do so by being both so resistant to desiccation and so amenable to dispersal on the air that their parasites can neither survive such punishing conditions nor spread as far nor as fast, allowing the asexual bdelloids to start afresh in (parasite-free) pastures anew. </jats:p>

<jats:title>The Best Things in Life Are Free?</jats:title> <jats:p> Does money buy happiness? Answers to this question differ, depending, in part, on whether one asks an economist or a psychologist. The former would point to correlations between higher incomes and greater self-reported well-being, whereas the latter would argue that happiness shows little correlation with absolute material goods and is instead dictated largely by an individual's so-called set-point. Another strand of research invokes a hedonic treadmill, whereby income matters until subsistence requirements are met, at which point comparisons with one's neighbors are what influence one's sense of life satisfaction. <jats:bold>Oswald and Wu</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="576" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1180606">576</jats:related-article> , published online 17 December; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5965" page="534" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1186315">Layard</jats:related-article> </jats:bold> ) establish that the subjective responses from 1 million adults, collected within health surveys conducted by the U.S. Centers for Disease Control and Prevention, do indeed correlate with objective measures of quality of life. </jats:p>

<jats:title>Platelet Microparticles Drive Inflammatory Arthritis</jats:title> <jats:p> Platelets are best known for their critical role in blood clot formation during wound repair, but an appreciation for their role in inflammatory processes is growing. Platelet-derived cellular microparticles (MPs) are small membrane vesicles released from platelets in response to cell activation that can transport biomolecules throughout the body that have also been implicated in inflammatory processes. <jats:bold> Boilard <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="580" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1181928">580</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="5965" page="528" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1185869">Zimmerman and Weyrich</jats:related-article> </jats:bold> ) have now found that platelet-derived MPs probably contribute to the inflammatory processes underlying rheumatoid arthritis, an autoimmune disease. The majority of MPs in synovial fluid from patients with various types of inflammatory arthritis were platelet-derived and, importantly, platelet-derived MPs were lacking in synovial fluid from osteoarthritis patients. Furthermore, platelet depletion abrogated disease development in a mouse model of inflammatory arthritis. </jats:p>

<jats:title>Columns, Connections, and Correlations</jats:title> <jats:p> What is the nature of interactions between neurons in neural circuits? The prevalent hypothesis suggests that dense local connectivity causes nearby cortical neurons to receive substantial amounts of common input, which in turn leads to strong correlations between them. Now two studies challenge this view, which impacts our fundamental understanding of coding in the cortex. <jats:bold> Ecker <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="584" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1179867">584</jats:related-article> ) investigated the statistics of correlated firing in pairs of neurons from area V1 of awake macaque monkeys. In contrast to previous studies, correlations turned out to be very low, irrespective of the stimulus being shown to the animals, the distances of the recording sites, and the similarity of the neuron's receptive fields or response properties. In an accompanying modeling and recording paper, <jats:bold> Renart <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="587" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1179850">587</jats:related-article> ) demonstrate how it is possible to have zero noise correlation, even among cells with common input. </jats:p>

<jats:title>Columns, Connections, and Correlations</jats:title> <jats:p> What is the nature of interactions between neurons in neural circuits? The prevalent hypothesis suggests that dense local connectivity causes nearby cortical neurons to receive substantial amounts of common input, which in turn leads to strong correlations between them. Now two studies challenge this view, which impacts our fundamental understanding of coding in the cortex. <jats:bold> Ecker <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="584" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1179867">584</jats:related-article> ) investigated the statistics of correlated firing in pairs of neurons from area V1 of awake macaque monkeys. In contrast to previous studies, correlations turned out to be very low, irrespective of the stimulus being shown to the animals, the distances of the recording sites, and the similarity of the neuron's receptive fields or response properties. In an accompanying modeling and recording paper, <jats:bold> Renart <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="587" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1179850">587</jats:related-article> ) demonstrate how it is possible to have zero noise correlation, even among cells with common input. </jats:p>

<jats:title>When Polymerases Collide</jats:title> <jats:p> Genomes must be replicated by DNA polymerase and copied by RNA polymerase. The two processes occur concurrently in bacteria and, although the majority of bacterial genes are co-oriented with replication, head-on collisions still occur and can result in double-strand breaks in the genome. <jats:bold>Pomerantz and O'Donnell</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="590" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1179595" xlink:type="simple">590</jats:related-article> ) show, in vitro, that both <jats:italic>Escherichia coli</jats:italic> DNA and RNA polymerases grind to a halt when they collide bumper to bumper but that the replication fork remains intact, with the RNA polymerase being shunted off the DNA and out of the way. Mfd, a transcription-repair coupling factor, promotes DNA replication restart probably by rewinding separated DNA stands ahead of the halted transcription complex, promoting its displacement from the DNA. </jats:p>

<jats:title>Gut Check</jats:title> <jats:p> The gastrointestinal (GI) tract is particularly sensitive to damage by ionizing radiation. Despite decades of study, fundamental questions such as which cells and which molecular mechanisms mediate this GI damage remain a source of great controversy. Studying a series of genetically manipulated mice, <jats:bold> Kirsch <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="593" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1166202">593</jats:related-article> , published online 17 December) conclude that GI epithelial cells, rather than endothelial cells, are the critical cellular targets of radiation damage and that apoptosis (a well-studied mechanism of cell death) is not a major contributor to the damage. Rather, an alternative cell-death pathway whose activity is inhibited by the tumor suppressor protein p53 appears to mediate GI damage. Further insights into this pathway may assist the development of medical counter-measures for preventing and treating radiation-induced tissue damage. </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> The show includes dealing with parasites in the absence of sex, the advent of quantum machines, your Letters to <jats:italic>Science</jats:italic> , and more. </jats:p>