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<jats:p> Highlights from the <jats:italic>Science</jats:italic> family of journals </jats:p>

<jats:p>Editors’ selections from the current scientific literature</jats:p>

<jats:p> In many vertebrate and invertebrate organisms, gametes develop within groups of interconnected cells called germline cysts formed by several rounds of incomplete divisions. We found that loss of the deubiquitinase USP8 gene in <jats:italic>Drosophila</jats:italic> can transform incomplete divisions of germline cells into complete divisions. Conversely, overexpression of USP8 in germline stem cells is sufficient for the reverse transformation from complete to incomplete cytokinesis. The ESCRT-III proteins CHMP2B and Shrub/CHMP4 are targets of USP8 deubiquitinating activity. In <jats:italic>Usp8</jats:italic> mutant sister cells, ectopic recruitment of ESCRT proteins at intercellular bridges causes cysts to break apart. A Shrub/CHMP4 variant that cannot be ubiquitinated does not localize at abscission bridges and cannot complete abscission. Our results uncover ubiquitination of ESCRT-III as a major switch between two types of cell division. </jats:p>

<jats:p>Epistatic interactions can make the outcomes of evolution unpredictable, but no comprehensive data are available on the extent and temporal dynamics of changes in the effects of mutations as protein sequences evolve. Here, we use phylogenetic deep mutational scanning to measure the functional effect of every possible amino acid mutation in a series of ancestral and extant steroid receptor DNA binding domains. Across 700 million years of evolution, epistatic interactions caused the effects of most mutations to become decorrelated from their initial effects and their windows of evolutionary accessibility to open and close transiently. Most effects changed gradually and without bias at rates that were largely constant across time, indicating a neutral process caused by many weak epistatic interactions. Our findings show that protein sequences drift inexorably into contingency and unpredictability, but that the process is statistically predictable, given sufficient phylogenetic and experimental data.</jats:p>

<jats:p> Respiration is a core biological energy–converting process whose last steps are carried out by a chain of multisubunit complexes in the inner mitochondrial membrane. To probe the functional and structural diversity of eukaryotic respiration, we examined the respiratory chain of the ciliate <jats:italic>Tetrahymena thermophila</jats:italic> (Tt). Using cryo–electron microscopy on a mixed sample, we solved structures of a supercomplex between Tt complex I (Tt-CI) and Tt-CIII <jats:sub>2</jats:sub> (Tt-SC I+III <jats:sub>2</jats:sub> ) and a structure of Tt-CIV <jats:sub>2</jats:sub> . Tt-SC I+III <jats:sub>2</jats:sub> (~2.3 megadaltons) is a curved assembly with structural and functional symmetry breaking. Tt-CIV <jats:sub>2</jats:sub> is a ~2.7-megadalton dimer with more than 50 subunits per protomer, including mitochondrial carriers and a TIM8 <jats:sub>3</jats:sub> -TIM13 <jats:sub>3</jats:sub> –like domain. Our structural and functional study of the <jats:italic>T. thermophila</jats:italic> respiratory chain reveals divergence in key components of eukaryotic respiration, thereby expanding our understanding of core metabolism. </jats:p>

<jats:p>Forest restoration is being scaled up globally to deliver critical ecosystem services and biodiversity benefits; however, there is a lack of rigorous comparison of cobenefit delivery across different restoration approaches. Through global synthesis, we used 25,950 matched data pairs from 264 studies in 53 countries to assess how delivery of climate, soil, water, and wood production services, in addition to biodiversity, compares across a range of tree plantations and native forests. Benefits of aboveground carbon storage, water provisioning, and especially soil erosion control and biodiversity are better delivered by native forests, with compositionally simpler, younger plantations in drier regions performing particularly poorly. However, plantations exhibit an advantage in wood production. These results underscore important trade-offs among environmental and production goals that policy-makers must navigate in meeting forest restoration commitments.</jats:p>

<jats:p> Kinetochores assemble onto specialized centromeric CENP-A (centromere protein A) nucleosomes (CENP-A <jats:sup>Nuc</jats:sup> ) to mediate attachments between chromosomes and the mitotic spindle. We describe cryo–electron microscopy structures of the human inner kinetochore constitutive centromere associated network (CCAN) complex bound to CENP-A <jats:sup>Nuc</jats:sup> reconstituted onto α-satellite DNA. CCAN forms edge-on contacts with CENP-A <jats:sup>Nuc</jats:sup> , and a linker DNA segment of the α-satellite repeat emerges from the fully wrapped end of the nucleosome to thread through the central CENP-LN channel that tightly grips the DNA. The CENP-TWSX histone-fold module further augments DNA binding and partially wraps the linker DNA in a manner reminiscent of canonical nucleosomes. Our study suggests that the topological entrapment of the linker DNA by CCAN provides a robust mechanism by which kinetochores withstand both pushing and pulling forces exerted by the mitotic spindle. </jats:p>