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Sudden olfactory loss in the absence of concurrent nasal congestion is now a well‐recognized symptom of COVID‐19. We examined olfaction using standardized objective tests of odour detection, identification and hedonics collected from asymptomatic university students before and as SARS‐CoV‐2 emerged locally. Olfactory performance of students who were tested when the virus is known to be endemic (n = 22) was compared to students tested in the month prior to viral circulation (n = 25), a normative sample assessed during the previous 4 years (n = 272) and those tested in prior years during the same time period. Analyses showed significantly reduced odour detection for the virus exposed cohort compared to students tested before (t = 2.60; P =.01; d = 0.77; CI 0.17, 1.36) and to the normative sample (D = 0.38; P =.005). Odour identification scores were similar, but the exposed cohort rated odours as less unpleasant (P <.001, CLES = 0.77). Hyposmia increased 4.4‐fold for students tested 2 weeks before school closure (N = 22) and increased 13.6‐fold for students tested in the final week (N = 11). While the unavailability of COVID‐19 testing is a limitation, this naturalistic study demonstrates week‐by‐week increase in hyposmia in asymptomatic students as a virus was circulating on campus, consistent with increasing airborne viral loads. The specific hedonic deficit in unpleasantness appraisal suggests a deficit in the TAAR olfactory receptor class, which conveys the social salience of odours. Assessment of odour detection and hedonic ratings may aid in early detection of SARS‐CoV‐2 exposure in asymptomatic and pre‐symptomatic persons. [ABSTRACT FROM AUTHOR]

Ontogenetic shifts in plants are ubiquitous, but their ecological and evolutionary significance remain largely unknown. Juveniles have few opportunities to accumulate sufficient biomass to withstand damage, whereas adults allocate resources to reproduction. Thus, age‐specific environmental filters are expected to drive selection towards specific resource‐investment strategies for each developmental stage.We tested whether species exhibited strategies that favour faster rates of biomass accumulation during early developmental stages to cope with vulnerability, shifting towards habitat‐dependent strategies to optimise resource acquisition and use later on. We also hypothesised that juveniles exhibit greater intraspecific variability of strategies than adults, as a result of continuous filtering of traits throughout the plant's development towards adulthood.We measured key leaf traits—leaf area (LA), leaf dry matter content (LDMC) and specific leaf area (SLA)—and calculated scores for competitor (C), stress‐tolerator (S), ruderal (R) strategies of the CSR system for juveniles of 54 species and conspecific adults of 27 species naturally occurring either in unproductive (grassland) or productive (forest) habitats.Juveniles exhibited higher SLA and LA and lower LDMC, and thus a more R‐strategy in both habitats when compared with adults, but were not necessarily "R" in absolute terms. We also found smaller intraspecific variation for the R‐strategy in adults compared with juveniles in both habitats, whereas the variation of the other strategies was habitat dependent.Ontogenetic shifts in ecological strategies appear to have been selected as a response to ontogeny‐dependent filters. Thus, strategies that favour less costly leaves and faster growth rates (relatively R‐selected) in juveniles shift towards C and/or S strategies in adulthood, depending on habitat productivity. Nevertheless, habitat‐dependent specialisation seems to be a major driver of ecological strategy selection in juveniles. Our study reveals ontogeny‐dependent strategies, offering a new approach to integrate plant development and functional specialisation. A plain language summary is available for this article. Plain Language Summary [ABSTRACT FROM AUTHOR]

During Bacillus subtilis sporulation, an endocytic-like process called engulfment results in one cell being entirely encased in the cytoplasm of another cell. The driving force underlying this process of membrane movement has remained unclear, although components of the machinery have been characterized. Here we provide evidence that synthesis of peptidoglycan, the rigid, strength bearing extracellular polymer of bacteria, is a key part of the missing force-generating mechanism for engulfment. We observed that sites of peptidoglycan synthesis initially coincide with the engulfing membrane and later with the site of engulfment membrane fission. Furthermore, compounds that block muropeptide synthesis or polymerization prevented membrane migration in cells lacking a component of the engulfment machinery (SpoIIQ), and blocked the membrane fission event at the completion of engulfment in all cells. In addition, these compounds inhibited bulge and vesicle formation that occur in spoIID mutant cells unable to initiate engulfment, as did genetic ablation of a protein that polymerizes muropeptides. This is the first report to our knowledge that peptidoglycan synthesis is necessary for membrane movements in bacterial cells and has implications for the mechanism of force generation during cytokinesis. [ABSTRACT FROM AUTHOR]