Catálogo de publicaciones - revistas

<jats:title>Deformation powers the nucleosome slide</jats:title> <jats:p> In eukaryotes, DNA is packed onto nucleosomes. For transcription factors and other proteins to gain access to DNA, nucleosomes must be moved out of the way, or “remodeled”—but not disassembled. Nucleosomes are composed of histone protein octamers, the cores of which have generally been considered to be fairly rigid. Sinha <jats:italic>et al.</jats:italic> used nuclear magnetic resonance and protein cross-linking to show that one of the enzyme complexes that remodel nucleosomes, SNF2h, is able to distort the histone octamer (see the Perspective by Flaus and Owen-Hughes). Nucleosome deformation was important for this remodeler to be able to slide nucleosomes out of the way. </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.aaa3761">10.1126/science.aaa3761</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6322" page="245" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aam5403">245</jats:related-article> </jats:p>

<jats:title>Working as a pair</jats:title> <jats:p> Enzymes provide scaffolds that facilitate chemical reactions. Enzyme dynamics often enhance reactivity by allowing the enzyme to sample the transition state between reactants and products. Kim <jats:italic>et al.</jats:italic> explored the role of dynamics in the dimeric enzyme fluoroacetate dehalogenase (see the Perspective by Saleh and Kalodimos). They found that the two protomers are asymmetric, with only one being able to bind substrate at a time. The nonbinding protomer contributed to catalysis by becoming more dynamic to compensate for the entropy loss of its partner. </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.aag2355">10.1126/science.aag2355</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6322" page="247" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aal4632">247</jats:related-article> </jats:p>

<jats:title>Ethics of organoid research</jats:title> <jats:p> Growing functional human tissues and organs would provide much needed material for regeneration and repair. New technologies are taking us in that direction. In addition to their use in regenerative medicine, stem cells that grow and morph into organ-like structures known as organoids can be used in drug development and toxicology testing. The potential developments and possibilities are numerous and affect not only biomedicine but also areas of ongoing ethical debate, such as animal experimentation, research on human embryos and fetuses, ethics review, and patient consent. Bredenoord <jats:italic>et al.</jats:italic> review how organoids affect existing ethical debates and how they raise novel ethical dilemmas and professional responsibilities. </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.aaf9414">10.1126/science.aaf9414</jats:related-article> </jats:p>

<jats:title>Chromosomal chaos and tumor immunity</jats:title> <jats:p> Cancer immunotherapy produces durable clinical responses in only a subset of patients. Identification of tumor characteristics that correlate with responses could lead to predictive biomarkers and shed light on causal mechanisms. Davoli <jats:italic>et al.</jats:italic> found that human tumors with extensive aneuploidy—i.e., that display a highly abnormal number of chromosomes and chromosomal segments—express fewer markers of the immune cells responsible for tumor destruction. In a retrospective analysis of clinical trial data, they found that melanoma patients with highly aneuploid tumors were less likely to benefit from immune checkpoint blockade therapy than patients whose tumors had a more normal karyotype. Thus, aneuploidy appears to enhance the ability of tumors to evade the immune system. </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.aaf8399">10.1126/science.aaf8399</jats:related-article> </jats:p>

<jats:p>The new year brings opportunities to think creatively about finding solutions to difficult problems. It's a chance to affirm that although views may differ dramatically, we should try to work effectively with one another. My namesake believed in this. Jeremy Stone, the long-time president of the Federation of American Scientists, passed away on 1 January at the age of 81. As a graduate student, Stone attended mathematics classes taught by my father, and he and his wife Betty Jane (B.J.) Stone, also a distinguished mathematician and statistician, babysat my brother and me. Stone's career followed a remarkable and unusual path for a scientist—indeed, for anyone—and highlights how individuals with training in science, technology, engineering, and mathematics can contribute to society in diverse and profound ways.</jats:p>

<jats:p>A roundup of weekly science policy and related news.</jats:p>

<jats:p>Researchers frozen out as parties vie for control of research station.</jats:p>