Regulation of Freshwater Community Structure at Multiple Intensities of Dragonfly Predation

We examined the role played by predaceous dragonfly nymphs, Celithemis fasciata (Odonata: Libellulidae), in the regulation of the community structure of a benthic macroinvertebrate assemblage in Par Pond, an 1100-ha reservoir in South Carolina. Effects of predation intensity on species richness, evenness, and density were evaluated by adding zero, two, four, and eight large dragonfly nymphs (antepenultimate and penultimate instars) to previously sieved (0.85-mm mesh) bottom sediment containing benthic macroinvertebrates. Predator and prey assemblages were then placed in individualfieldmicrocosms that consisted of polyethylene trays surrounded by underwater screens (mesh <2 mm diagonally) and suspended 15 cm belowfloatingplatforms. Twelve replicates of each treatment level were run during each of three 6-wk experimental periods: April-May 1980, August-October 1980, and January-February 1981. In addition, colonization of microcosms by invertebrates was quantified, and samples from natural, unenclosed benthic fauna were collected seasonally along a transect for comparison with experimental assemblages. We tested whether predators enhanced, depressed, both increased and decreased, or had no effect on the complexity of the community structure. The dual effect of predation on community structure is predicted by Connell's "intermediate disturbance hypothesis." Results showed that dragonfly nymphs can significantly influence the structure of the benthic community. However, the results did not show that invertebrate predation is the sole or even the primary regulator of community structure. Species richness was significantly greater at intermediate treatment levels (thus supporting Connell's general hypothesis), but the increase was not great (a range of -10%). The mechanisms by which species richness is maximized at intermediate intensities of predation are not entirely evident, but are probably a combination of prey refuges and nonselective predation with patch switching. In contrast, species evenness, as measured by equitability and by Simpson's index, was greatest at the highest predation level (which does not support the intermediate disturbance hypothesis). Dragonflies appeared to exert a greater influence on prey density than on community diversity

A high resolution RH map of the bovine major histocompatibility complex

<p>Abstract</p> <p>Background</p> <p>The cattle MHC is termed the bovine leukocyte antigen (BoLA) and, along with the MHCs of other ruminants, is unique in its genomic organization. Consequently, correct and reliable gene maps and sequence information are critical to the study of the BoLA region. The bovine genome sequencing project has produced two assemblies (Btau_3.1 and 4.0) that differ substantially from each other and from conventional gene maps in the BoLA region. To independently compare the accuracies of the different sequence assemblies, we have generated a high resolution map of BoLA using a 12,000_radradiation hybrid panel. Seventy-seven unique sequence tagged site (STS) markers chosen at approximately 50 kb intervals from the Btau 2.0 assembly and spanning the IIa-III-I and IIb regions of the bovine MHC were mapped on a 12,000_radbovine radiation hybrid (RH) panel to evaluate the different assemblies of the bovine genome sequence.</p> <p>Results</p> <p>Analysis of the data generated a high resolution RH map of BoLA that was significantly different from the Btau_3.1 assembly of the bovine genome but in good agreement with the Btau_4.0 assembly. Of the few discordancies between the RH map and Btau_4.0, most could be attributed to closely spaced markers that could not be precisely ordered in the RH panel. One probable incorrectly-assembled sequence and three missing sequences were noted in the Btau_4.0 assembly. The RH map of BoLA is also highly concordant with the sequence-based map of HLA (NCBI build 36) when reordered to account for the ancestral inversion in the ruminant MHC.</p> <p>Conclusion</p> <p>These results strongly suggest that studies using Btau_3.1 for analyses of the BoLA region should be reevaluated in light of the Btau_4.0 assembly and indicate that additional research is needed to produce a complete assembly of the BoLA genomic sequences.</p

Efficacy and safety of two neutralising monoclonal antibody therapies, sotrovimab and BRII-196 plus BRII-198, for adults hospitalised with COVID-19 (TICO): a randomised controlled trial

We aimed to assess the efficacy and safety of two neutralising monoclonal antibody therapies (sotrovimab [Vir Biotechnology and GlaxoSmithKline] and BRII-196 plus BRII-198 [Brii Biosciences]) for adults admitted to hospital for COVID-19 (hereafter referred to as hospitalised) with COVID-19. In this multinational, double-blind, randomised, placebo-controlled, clinical trial (Therapeutics for Inpatients with COVID-19 [TICO]), adults (aged ≥18 years) hospitalised with COVID-19 at 43 hospitals in the USA, Denmark, Switzerland, and Poland were recruited. Patients were eligible if they had laboratory-confirmed SARS-CoV-2 infection and COVID-19 symptoms for up to 12 days. Using a web-based application, participants were randomly assigned (2:1:2:1), stratified by trial site pharmacy, to sotrovimab 500 mg, matching placebo for sotrovimab, BRII-196 1000 mg plus BRII-198 1000 mg, or matching placebo for BRII-196 plus BRII-198, in addition to standard of care. Each study product was administered as a single dose given intravenously over 60 min. The concurrent placebo groups were pooled for analyses. The primary outcome was time to sustained clinical recovery, defined as discharge from the hospital to home and remaining at home for 14 consecutive days, up to day 90 after randomisation. Interim futility analyses were based on two seven-category ordinal outcome scales on day 5 that measured pulmonary status and extrapulmonary complications of COVID-19. The safety outcome was a composite of death, serious adverse events, incident organ failure, and serious coinfection up to day 90 after randomisation. Efficacy and safety outcomes were assessed in the modified intention-to-treat population, defined as all patients randomly assigned to treatment who started the study infusion. This study is registered with ClinicalTrials.gov, NCT04501978. Between Dec 16, 2020, and March 1, 2021, 546 patients were enrolled and randomly assigned to sotrovimab (n=184), BRII-196 plus BRII-198 (n=183), or placebo (n=179), of whom 536 received part or all of their assigned study drug (sotrovimab n=182, BRII-196 plus BRII-198 n=176, or placebo n=178; median age of 60 years [IQR 50–72], 228 [43%] patients were female and 308 [57%] were male). At this point, enrolment was halted on the basis of the interim futility analysis. At day 5, neither the sotrovimab group nor the BRII-196 plus BRII-198 group had significantly higher odds of more favourable outcomes than the placebo group on either the pulmonary scale (adjusted odds ratio sotrovimab 1·07 [95% CI 0·74–1·56]; BRII-196 plus BRII-198 0·98 [95% CI 0·67–1·43]) or the pulmonary-plus complications scale (sotrovimab 1·08 [0·74–1·58]; BRII-196 plus BRII-198 1·00 [0·68–1·46]). By day 90, sustained clinical recovery was seen in 151 (85%) patients in the placebo group compared with 160 (88%) in the sotrovimab group (adjusted rate ratio 1·12 [95% CI 0·91–1·37]) and 155 (88%) in the BRII-196 plus BRII-198 group (1·08 [0·88–1·32]). The composite safety outcome up to day 90 was met by 48 (27%) patients in the placebo group, 42 (23%) in the sotrovimab group, and 45 (26%) in the BRII-196 plus BRII-198 group. 13 (7%) patients in the placebo group, 14 (8%) in the sotrovimab group, and 15 (9%) in the BRII-196 plus BRII-198 group died up to day 90. Neither sotrovimab nor BRII-196 plus BRII-198 showed efficacy for improving clinical outcomes among adults hospitalised with COVID-19. US National Institutes of Health and Operation Warp Spee