Catálogo de publicaciones - revistas

<jats:title>Support for the memory index theory</jats:title> <jats:p> The link between contextual memory representations and locations or routes represented by hippocampal place cells during exploration remains unknown. Tanaka <jats:italic>et al.</jats:italic> examined spatial firing properties of neurons in hippocampal area CA1 on the basis of whether they had recently expressed the immediate-early activity-induced gene <jats:italic>c-Fos</jats:italic> in response to a novel context. The c-Fos–positive neurons displayed a more on-off firing pattern than the c-Fos–negative cells during context discrimination. In a contextual recognition paradigm, these results support the index theory of hippocampal function over a cognitive mapping theory. </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="6400" page="392" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aat5397">392</jats:related-article> </jats:p>

<jats:title>The benefits of being well fed</jats:title> <jats:p> In eusocial insects, the vast majority of individuals sacrifice their reproductive potential to support the reproductive queen. Although this system has evolved repeatedly, there is still much debate surrounding its origin. Working with seven different species of ants, Chandra <jats:italic>et al.</jats:italic> used a transcriptomic approach to show that a single gene is consistently up-regulated in queens. This gene seems to confer reproductive status through integration with increased nutrition. In a clonal ant, larval signals disrupt this gene up-regulation, destabilizing the division of reproductive labor. Increasing levels of the associated peptide override these larval signals and establish eusociality. </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="6400" page="398" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aar5723">398</jats:related-article> </jats:p>

<jats:title>Sticky bacteria tolerated as future food</jats:title> <jats:p> <jats:italic>Dictyostelium discoideum</jats:italic> amoebae consume bacteria until the supply is exhausted. Then the amoeba cells clump together into a “slug” and initiate a complex multicellular reproductive phase. Specialized cells within aggregates rid the slug of any extracellular bacteria. However, some strains of amoeba tolerate live, intracellular bacteria. Dinh <jats:italic>et al.</jats:italic> discovered that these carrier strains bear surface lectins that bind <jats:italic>Klebsiella</jats:italic> bacteria, promote cell entry, and prevent the bacteria from being immediately digested. These bacteria then provide a future food source. Moreover, the internalized bacteria transfer DNA into the amoeba nucleus, resulting in transient genetic transformation. </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="6400" page="402" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aat2058">402</jats:related-article> </jats:p>

<jats:title>Inflammation promotes gut polyposis</jats:title> <jats:p> Peutz–Jeghers Syndrome (PJS) causes benign polyps in the gut and a higher risk of several cancers caused by mutations in the tumor suppressor gene <jats:italic>STK11</jats:italic> , which encodes liver kinase B1 (LKB1). LKB1's role in this disease is thought to be related to its tumor suppressor function. Now, Poffenberger <jats:italic>et al.</jats:italic> show that the T cell–specific heterozygous deletion of <jats:italic>Stk11</jats:italic> is sufficient to reproduce PJS symptoms in mice (see the Perspective by Hollstein and Shaw). Polyps in mice and humans are characterized by immune cell infiltration, enhanced STAT3 signaling, and increased levels of inflammatory cytokines such as interleukin-6 (IL-6). Targeting STAT3 signaling, IL-6, or T cells ameliorated the polyps, suggesting potential therapies for this disease. </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="6400" page="406" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aan3975">406</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6400" page="332" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aau4804">332</jats:related-article> </jats:p>

<jats:title>Phase separation and gene control</jats:title> <jats:p> Many components of eukaryotic transcription machinery—such as transcription factors and cofactors including BRD4, subunits of the Mediator complex, and RNA polymerase II—contain intrinsically disordered low-complexity domains. Now a conceptual framework connecting the nature and behavior of their interactions to their functions in transcription regulation is emerging (see the Perspective by Plys and Kingston). Chong <jats:italic>et al.</jats:italic> found that low-complexity domains of transcription factors form concentrated hubs via functionally relevant dynamic, multivalent, and sequence-specific protein-protein interaction. These hubs have the potential to phase-separate at higher concentrations. Indeed, Sabari <jats:italic>et al.</jats:italic> showed that at super-enhancers, BRD4 and Mediator form liquid-like condensates that compartmentalize and concentrate the transcription apparatus to maintain expression of key cell-identity genes. Cho <jats:italic>et al.</jats:italic> further revealed the differential sensitivity of Mediator and RNA polymerase II condensates to selective transcription inhibitors and how their dynamic interactions might initiate transcription elongation. </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" related-article-type="in-this-issue" xlink:href="10.1126/science.aar2555">eaar2555</jats:related-article> , p. <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.aar3958">eaar3958</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6400" page="412" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aar4199">412</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6400" page="329" related-article-type="in-this-issue" vol="361" xlink:href="10.1126/science.aau4795">329</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>