Catálogo de publicaciones - revistas

<jats:title>Refined understanding of the preprophase band</jats:title> <jats:p> Because plant cells do not move, plant tissues are constructed according to how they place the divisions of their constituent cells. Schaefer <jats:italic>et al.</jats:italic> found a mutation in the model plant <jats:italic>Arabidopsis</jats:italic> that abolishes a visible precursor of cell division, the preprophase band. Despite loss of the band—previously thought essential to define the division plane—the general orientations of cell division planes in the roots of these plants were normal. However, individual division orientations showed more variance than normal. Thus, the preprophase band serves to focus and refine the final orientation of the nascent cell division plane. </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="6334" page="186" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aal3016">186</jats:related-article> </jats:p>

<jats:title>Making an unbiased library</jats:title> <jats:p> Sequencing the genome of single cells gives insight into issues such as cell-to-cell heterogeneity and genome instability. Key to single-cell sequencing techniques are whole-genome amplification (WGA) methods that provide sufficient DNA for next-generation sequencing. Current WGA methods have been hampered by low accuracy and spatial resolution of gene copy numbers and by low amplification fidelity. Chen <jats:italic>et al.</jats:italic> report an improved single-cell WGA method, Linear Amplification via Transposon Insertion (LIANTI). The DNA is randomly fragmented by Tn5 transposition of a transposon that includes a T7 promoter, which allows linear amplification. The authors used the method to determine the spectrum of single-nucleotide variations in a single human cell after ultraviolet radiation. </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="6334" page="189" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aak9787">189</jats:related-article> </jats:p>

<jats:title>Coupling transcription and translation</jats:title> <jats:p> In bacteria, the transcription of DNA into mRNA by RNA polymerase is coupled to the translation of that mRNA into protein by the ribosome. How this coupling is achieved has been unclear. Kohler <jats:italic>et al.</jats:italic> show that RNA polymerase and the ribosome from <jats:italic>Escherichia coli</jats:italic> can form a so-called expressome complex. Electron microscopy structural analysis, together with functional experiments, revealed details of the coupled complex. The coupling could allow translation to prevent transcriptional pausing, backtracking, and termination. </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="6334" page="194" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aal3059">194</jats:related-article> </jats:p>

<jats:title>How the flagellum knows when to stop</jats:title> <jats:p> The bacterial flagellum is important in bacterial pathogenesis and biofilm formation. It is a rotary nanomotor that allows bacteria to propel themselves through liquids and across surfaces. Researchers interested in nanoscale robotics use the bacterial flagellum as a model for a machine that self-assembles on the nanoscale. Cohen <jats:italic>et al.</jats:italic> examined exactly how the flagellum precisely measures its shaft so that it spans, but does not extend beyond the edge of, the periplasm. The growing flagellum uses a mechanism by which it “senses” when it hits the outer membrane and stops growing. Changing the width of the periplasmic space by remodeling a particular lipid changed the length of the flagellar shaft. </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="6334" page="197" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aam6512">197</jats:related-article> </jats:p>

<jats:title>Targeting nonviral antigens in viral-driven cancer</jats:title> <jats:p> Adoptive cell transfer harnesses a patient's own T cells to destroy cancer. The strategy can successfully treat epithelial tumors driven by human papillomavirus (HPV), but it remains unclear why only some patients respond. Stevanović <jats:italic>et al.</jats:italic> examined the antitumor T cell response associated with HPV <jats:sup>+</jats:sup> cervical cancers that underwent complete regression. Unexpectedly, reactive T cells were not directed against virally associated antigens, but rather against cancer germline antigens or neoantigens not previously recognized by the immune system. These findings counter the widely held belief that T cell responses against viral antigens are responsible for therapeutic effects in HPV-driven cancers. </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="6334" page="200" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aak9510">200</jats:related-article> </jats:p>

<jats:title>Nucleosomes in contact</jats:title> <jats:p> In eukaryotic cells, genomic DNA must be compacted to fit inside the nucleus. A key player in DNA packaging is the nucleosome, which comprises a segment of DNA wrapped around an octamer of histone proteins. During replication and transcription, nucleosomes must reposition themselves on the DNA. In this process, nucleosomes can collide to form a dinucleosome. Kato <jats:italic>et al.</jats:italic> report a high-resolution crystal structure of a dinucleosome. One of the octamers has lost a histone dimer so that the dinucleosome comprises an octamer and a hexamer. The structure may represent an intermediate during chromatin remodeling. </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="6334" page="205" related-article-type="in-this-issue" vol="356" xlink:href="10.1126/science.aak9867">205</jats:related-article> </jats:p>

<jats:p> Exosomes—small, membrane-derived extracellular vesicles capable of carrying diverse biological cargo including proteins and microRNAs—have been found in a broad range of biological fluids and appear to be predominantly involved in cell-to-cell communication. Their natural characteristics make them uniquely suited for research and clinical applications, including as biomarkers both for diseases and for intrinsic biological activity. In fact, exosomes have been postulated to mediate the biological cross-talk that takes place between tumors and their surrounding environment that drives those tumors toward a metastatic state. In addition, exosomes are being co-opted as a treatment modality and have been modified through their parental cells to express a targeting moiety or marker tag on their surface. They can also be manipulated to carry drug formulations that can be applied to the treatment of a wide variety of disorders, such as cancer and various infectious, cardiovascular, and neurodegenerative diseases. <jats:list list-type="bullet"> <jats:list-item> <jats:p> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.sciencemag.org/custom-publishing/webinars/translational-applications-exosome-research-biomarker-discovery-drug">View the Webinar</jats:ext-link> </jats:p> </jats:list-item> </jats:list> </jats:p>

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