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An early Miocene extinction in pelagic sharks

Science - issue - Čt, 06/03/2021 - 19:40

Shark populations have been decimated in recent decades because of overfishing and other anthropogenic stressors; however, the long-term impacts of such changes in marine predator abundance and diversity are poorly constrained. We present evidence for a previously unknown major extinction event in sharks that occurred in the early Miocene, ~19 million years ago. During this interval, sharks virtually disappeared from open-ocean sediments, declining in abundance by >90% and morphological diversity by >70%, an event from which they never recovered. This abrupt extinction occurred independently from any known global climate event and ~2 million to 5 million years before diversifications in the highly migratory, large-bodied predators that dominate pelagic ecosystems today, indicating that the early Miocene was a period of rapid, transformative change for open-ocean ecosystems.

Comment on "Individual heterozygosity predicts translocation success in threatened desert tortoises"

Science - issue - Čt, 06/03/2021 - 19:40

Scott et al. (Reports, 27 November 2020, p. 1086) bring much-needed attention to species conservation by demonstrating heterozygote superiority among translocated tortoises. However, we believe that their recommended heterozygosity decision rule risks taking conservation genomics backward. We argue that their advice could misguide conservation management aimed at establishing viable populations, and that it can be improved by also assessing the genetic load.

Prevalent, protective, and convergent IgG recognition of SARS-CoV-2 non-RBD spike epitopes

Science - issue - Čt, 06/03/2021 - 19:40

The molecular composition and binding epitopes of the immunoglobulin G (IgG) antibodies that circulate in blood plasma after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are unknown. Proteomic deconvolution of the IgG repertoire to the spike glycoprotein in convalescent subjects revealed that the response is directed predominantly (>80%) against epitopes residing outside the receptor binding domain (RBD). In one subject, just four IgG lineages accounted for 93.5% of the response, including an amino (N)-terminal domain (NTD)–directed antibody that was protective against lethal viral challenge. Genetic, structural, and functional characterization of a multidonor class of "public" antibodies revealed an NTD epitope that is recurrently mutated among emerging SARS-CoV-2 variants of concern. These data show that "public" NTD-directed and other non-RBD plasma antibodies are prevalent and have implications for SARS-CoV-2 protection and antibody escape.

New Products

Science - issue - Čt, 06/03/2021 - 19:40

Seeing beyond a test

Science - issue - Čt, 06/03/2021 - 19:40

Response to Comment on "Individual heterozygosity predicts translocation success in threatened desert tortoises"

Science - issue - Čt, 06/03/2021 - 19:40

Hansson et al. argue that our main finding could provide an overly simplistic metric for maximizing genetic rescue. They agree that translocating the most genetically diverse individuals led to a large increase in translocated tortoise survival, but recommend instead moving individuals that have low genetic load and the greatest representation of metapopulation diversity. Their recommendation is based on specific model assumptions and fitness effects that are often unknown and are not generalizable to many endangered species applications.

Comment on "Individual heterozygosity predicts translocation success in threatened desert tortoises"

Science - issue - Čt, 06/03/2021 - 19:40

Scott et al. (Reports, 27 November 2020, p. 1086) suggest, on the basis of conclusions obtained from a desert tortoise reintroduction program, that higher genomic heterozygosity should be used to identify individuals for successful translocation. I contend that this recommendation is questionable given these relocated tortoises’ unknown origin, their high mortality, insufficient data on resident tortoises and other components of fitness, and potential allelic dropout.

Response to Comment on "Individual heterozygosity predicts translocation success in threatened desert tortoises"

Science - issue - Čt, 06/03/2021 - 19:40

Hedrick brings up several potential concerns that he feels challenge or limit our main finding. Hedrick does not comment on our empirical results, but rather argues that several factors may confound or invalidate our conclusion. Many of these concerns focus on unknown ecological aspects of the translocated tortoises, but we believe there is no reason to conclude that they bias the results or interpretation as presented in our original paper.

The first 5 years of gravitational-wave astrophysics

Science - issue - Čt, 06/03/2021 - 19:40

Gravitational waves are ripples in spacetime generated by the acceleration of astrophysical objects; a direct consequence of general relativity, they were first directly observed in 2015. Here, I review the first 5 years of gravitational-wave detections. More than 50 gravitational-wave events have been found, emitted by pairs of merging compact objects such as neutron stars and black holes. These signals yield insights into the formation of compact objects and their progenitor stars, enable stringent tests of general relativity, and constrain the behavior of matter at densities higher than that of an atomic nucleus. Mergers that emit both gravitational and electromagnetic waves probe the formation of short gamma-ray bursts and the nucleosynthesis of heavy elements, and they measure the local expansion rate of the Universe.

Canonical T cell receptor docking on peptide-MHC is essential for T cell signaling

Science - issue - Čt, 06/03/2021 - 19:40

T cell receptor (TCR) recognition of peptide–major histocompatibility complexes (pMHCs) is characterized by a highly conserved docking polarity. Whether this polarity is driven by recognition or signaling constraints remains unclear. Using "reversed-docking" TCRβ-variable (TRBV) 17+ TCRs from the naïve mouse CD8+ T cell repertoire that recognizes the H-2Db–NP366 epitope, we demonstrate that their inability to support T cell activation and in vivo recruitment is a direct consequence of reversed docking polarity and not TCR–pMHCI binding or clustering characteristics. Canonical TCR–pMHCI docking optimally localizes CD8/Lck to the CD3 complex, which is prevented by reversed TCR–pMHCI polarity. The requirement for canonical docking was circumvented by dissociating Lck from CD8. Thus, the consensus TCR–pMHC docking topology is mandated by T cell signaling constraints.

Come on, CDC, we need you

Science - issue - Čt, 06/03/2021 - 19:40

News at a glance

Science - issue - Čt, 06/03/2021 - 19:40

The internet goes quantum

Science - issue - Čt, 06/03/2021 - 19:40

Summer reading 2021

Science - issue - Čt, 06/03/2021 - 19:40

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