Catálogo de publicaciones - revistas

<jats:title>Passivating traps in perovskites</jats:title> <jats:p> Low-temperature processing of planar organic-inorganic perovskite solar cells made through solution processing would allow for simpler manufacturing and the use of flexible substrates. However, materials currently in use form interfaces with charge carrier trap states that limit performance. Tan <jats:italic>et al.</jats:italic> used chlorine-capped TiO <jats:sub>2</jats:sub> colloidal nanocrystal films as an electron-selective layer, which limited interface recombination in solution-processed solar cells. Such cells achieved certified efficiencies of 19.5% for active areas of 1.1 cm <jats:sup>2</jats:sup> . </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="6326" page="722" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aai9081">722</jats:related-article> </jats:p>

<jats:title>Hydroamination gets a light push uphill</jats:title> <jats:p> Hydroamination of olefins is a broadly useful method for making carbon-nitrogen bonds. However, when both the amine and the olefin have multiple alkyl substituents, the reaction can become energetically unfavorable. Musacchio <jats:italic>et al.</jats:italic> used the energy in blue light to surmount this obstacle (see the Perspective by Buchanan and Hull). A photo-excited iridium complex oxidized the amine, which in turn bonded efficiently to the olefin, after which a thiophenol cocatalyst shuttled the electron back. The reaction could operate across a wide range of amine and olefin partners. </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="6326" page="727" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aal3010">727</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6326" page="690" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aam6382">690</jats:related-article> </jats:p>

<jats:title>Missing meadows fail to mop up microbes</jats:title> <jats:p> Seagrass meadows, a prominent feature of most healthy coastal ecosystems, are often also associated with shallow coral reefs. Many plants have bioremediation qualities, and seagrasses, of which there are 60 or so species, produce natural biocides. Lamb <jats:italic>et al.</jats:italic> found that the seagrass meadows of inhabited atolls near Sulawesi, Indonesia, ameliorated seawater pollution from human-origination bacteria. This effect extended to potential pathogens of marine invertebrates and fish: Reefs fringing the seagrass meadows showed significantly less impact from coral and fish 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="6326" page="731" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aal1956">731</jats:related-article> </jats:p>

<jats:title>Sugar rush</jats:title> <jats:p> Flying requires high levels of energy production, which causes muscular oxidative damage. Food-derived antioxidants can protect against such damage; however, nectar is devoid of these compounds. Levin <jats:italic>et al.</jats:italic> found that nectar-feeding hawkmoths fed high concentrations of sugar had lower levels of damage than unfed moths. Sugar-fed moths generated antioxidant compounds by shunting glucose through a pentose phosphate pathway. This mechanism may have allowed for the evolution of energy-intensive flying nectarivores. </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="6326" page="733" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aah4634">733</jats:related-article> </jats:p>

<jats:title>Touchdown for gut pathogen virulence</jats:title> <jats:p> <jats:italic>Escherichia coli</jats:italic> is transformed from a commensal organism into a pathogen by acquisition of genetic elements called pathogenicity islands (PAIs). Katsowich <jats:italic>et al.</jats:italic> investigated how the PAI virulence genes of enteropathogenic <jats:italic>E. coli</jats:italic> (EPEC) respond when the bacterium attaches to a host gut cell. EPEC first sticks to the host by means of pili and then uses a PAI-encoded type 3 secretion system (T3SS) to inject multiple effectors into the host cell. But not all virulence mediators are injected. For example, CesT, a bacterial chaperone, delivers virulence effectors into the T3SS apparatus. Then, within the bacterial cytoplasm, it interacts with a gene repressor called CsrA, which reprograms bacterial gene expression to help the bacteria to adapt to epithelial cell–associated life. </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="6326" page="735" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aah4886">735</jats:related-article> </jats:p>

<jats:title>Coordinating cell wall synthesis and cell division</jats:title> <jats:p> Most bacteria are protected by peptidoglycan cell walls, which must be remodeled to split the cell. Cell division requires the tubulin homolog FtsZ, a highly conserved cytoskeletal polymer that specifies the future site of division. Bisson-Filho <jats:italic>et al.</jats:italic> and Yang <jats:italic>et al.</jats:italic> found that the dynamic treadmilling of FtsZ filaments controls both the location and activity of the associated cell wall synthetic enzymes. This creates discrete sites of cell wall synthesis that circle around the division plane to divide the cell. </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="6326" page="739" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aak9973">739</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6326" page="744" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aak9995">744</jats:related-article> </jats:p>

<jats:title>Coordinating cell wall synthesis and cell division</jats:title> <jats:p> Most bacteria are protected by peptidoglycan cell walls, which must be remodeled to split the cell. Cell division requires the tubulin homolog FtsZ, a highly conserved cytoskeletal polymer that specifies the future site of division. Bisson-Filho <jats:italic>et al.</jats:italic> and Yang <jats:italic>et al.</jats:italic> found that the dynamic treadmilling of FtsZ filaments controls both the location and activity of the associated cell wall synthetic enzymes. This creates discrete sites of cell wall synthesis that circle around the division plane to divide the cell. </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="6326" page="739" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aak9973">739</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6326" page="744" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aak9995">744</jats:related-article> </jats:p>

<jats:title>Hair follicles: Secret to prevent scars?</jats:title> <jats:p> Although some animals easily regenerate limbs and heal broken flesh, mammals are generally not so gifted. Wounding can leave scars, which are characterized by a lack of hair follicles and cutaneous fat. Plikus <jats:italic>et al.</jats:italic> now show that hair follicles in both mice and humans can convert myofibroblasts, the predominant dermal cell in a wound, into adipocytes (see the Perspective by Chan and Longaker). The hair follicles activated the bone morphogenetic protein (BMP) signaling pathway and adipocyte transcription factors in the myofibroblast. Thus, it may be possible to reduce scar formation after wounding by adding BMP. </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="6326" page="748" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aai8792">748</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6326" page="693" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aam6748">693</jats:related-article> </jats:p>

<jats:title>When is a mutation a true genetic variant?</jats:title> <jats:p> Large-scale sequencing studies have set out to determine the low-frequency pathogenic genetic variants in individuals and populations. However, Chen <jats:italic>et al.</jats:italic> demonstrate that many so-called low-frequency genetic variants in large public databases may be due to DNA damage. They scored libraries sequenced with and without a DNA damage–repairing enzymatic mix to assess the proportion of true rare variants. It remains to be seen how best to repair DNA before sequencing to provide more accurate assessments of mutation. </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="6326" page="752" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aai8690">752</jats:related-article> </jats:p>

<jats:title> Vitamin B <jats:sub>3</jats:sub> protects mice from glaucoma </jats:title> <jats:p> Glaucoma is the most common cause of age-related blindness in the United States. There is currently no cure, and once vision is lost, the condition is irreversible. Williams <jats:italic>et al.</jats:italic> now report that vitamin B <jats:sub>3</jats:sub> (also known as niacin) prevents eye degeneration in glaucoma-prone mice (see the Perspective by Crowston and Trounce). Supplementing the diets of young mice with vitamin B <jats:sub>3</jats:sub> averted early signs of glaucoma. Vitamin B <jats:sub>3</jats:sub> also halted further glaucoma development in aged mice that already showed signs of the disease. Thus, healthy intake of vitamin B <jats:sub>3</jats:sub> may protect eyesight. </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="6326" page="756" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aal0092">756</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6326" page="688" related-article-type="in-this-issue" vol="355" xlink:href="10.1126/science.aam7935">688</jats:related-article> </jats:p>