Objective The COVID-19 pandemic has placed health care workers under psychological stress. Previous reviews show a high prevalence of mental disorders among health care workers, but these need updating and inclusion of studies written in Chinese. The aim of this systematic review and meta-analysis was to provide updated prevalence estimates for depression, anxiety and post-traumatic stress disorder (PTSD) among health care workers during the COVID-19 pandemic, benefitting from the inclusion of studies published in Chinese. Methods Systematic search of EMBASE, MEDLINE, PsycINFO, Global Health, Web of Science, CINAHL, Google Scholar and the Chinese databases SinoMed, WanfangMed, CNKI and CQVIP, for studies conducted between December 2019 and August 2020 on the prevalence of depression, anxiety and PTSD in health care workers during the COVID-19 pandemic. Studies published in both English and Chinese were included. Results Data on the prevalence of moderate depression, anxiety and PTSD was pooled across 65 studies involving 97,333 health care workers across 21 countries. The pooled prevalence of depression was 21.7% (95% CI, 18.3%-25.2%), of anxiety 22.1% (95% CI, 18.2%-26.3%), and of PTSD 21.5% (95% CI, 10.5%-34.9%). Prevalence estimates are also provided for a mild classification of each disorder. Pooled prevalence estimates of depression and anxiety were highest in studies conducted in the Middle-East (34.6%; 28.9%). Subgroup and meta-regression analyses were conducted across covariates, including sampling method and outcome measure. Conclusions This systematic review and meta-analysis has identified a high prevalence of moderate depression, anxiety and PTSD among health care workers during the COVID-19 pandemic. Appropriate support is urgently needed. The response would benefit from additional research on which interventions are effective at mitigating these risks.

METTL3 catalyzes the formation of N6 -methyl-adenosine (m 6 A) which has important roles in regulating various biological processes. However, the in vivo function of Mettl3 remains largely unknown in mammals. Here we generated germ cell-specific Mettl3 knockout mice and demonstrated that Mettl3 was essential for male fertility and spermatogenesis. The ablation of Mettl3 in germ cells severely inhibited spermatogonial differentiation and blocked the initiation of meiosis. Transcriptome and m 6 A profiling analysis revealed that genes functioning in spermatogenesis had altered profiles of expression and alternative splicing. Our findings provide novel insights into the function and regulatory mechanisms of Mettl3-mediated m 6 A modification in spermatogenesis and reproduction in mammals.

Population founding and spatial spread may profoundly influence later population genetic structure, but their effects are difficult to quantify when population history is unknown. We examined the genetic effects of founder group formation in a recently founded population of the animal-dispersed Vaccinium membranaceum (black huckleberry) on new volcanic deposits at Mount St Helens (Washington, USA) 24 years post-eruption. Using amplified fragment length polymorphisms and assignment tests, we determined sources of the newly founded population and characterized genetic variation within new and source populations. Our analyses indicate that while founders were derived from many sources, about half originated from a small number of plants that survived the 1980 eruption in pockets of remnant soil embedded within primary successional areas. We found no evidence of a strong founder effect in the new population; indeed genetic diversity in the newly founded population tended to be higher than in some of the source regions. Similarly, formation of the new population did not increase among-population genetic variance, and there was no evidence of kin-structured dispersal in the new population. These results indicate that high gene flow among sources and long-distance dispersal were important processes shaping the genetic diversity in this young V. membranaceum population. Other species with similar dispersal abilities may also be able to colonize new habitats without significant reduction in genetic diversity or increase in differentiation among populations.

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