Biology subjects

Hall, E.

Publications and source records attributed to Hall, E..

22 records · Page 2Linked to original sources

bioRxiv2021

Persistence of SARS CoV-2 S1 Protein in CD16+ Monocytes in Post-Acute Sequelae of COVID-19 (PASC) Up to 15 Months Post-Infection

The recent COVID-19 pandemic is a treatment challenge in the acute infection stage but the recognition of chronic COVID-19 symptoms termed post-acute sequelae SARS-CoV-2 infection (PASC) may affect up to 30% of all infected individuals. The underlying mechanism and source of this distinct immunologic condition three months or more after initial infection remains elusive. Here, we investigated the presence of SARS-CoV-2 S1 protein in 46 individuals. We analyzed T-cell, B-cell, and monocytic subsets in both severe COVID-19 patients and in patients with post-acute sequelae of COVID-19 (PASC). The levels of both intermediate (CD14+, CD16+) and non-classical monocyte (CD14Lo, CD16+) were significantly elevated in PASC patients up to 15 months post-acute infection compared to healthy controls (P=0.002 and P=0.01, respectively). A statistically significant number of non-classical monocytes contained SARS-CoV-2 S1 protein in both severe (P=0.004) and PASC patients (P=0.02) out to 15 months post-infection. Non-classical monocytes were sorted from PASC patients using flow cytometric sorting and the SARS-CoV-2 S1 protein was confirmed by mass spectrometry. Cells from 4 out of 11 severe COVID-19 patients and 1 out of 26 PASC patients contained ddPCR+ peripheral blood mononuclear cells, however, only fragmented SARS-CoV-2 RNA was found in PASC patients. No full length sequences were identified, and no sequences that could account for the observed S1 protein were identified in any patient. Non-classical monocytes are capable of causing inflammation throughout the body in response to fractalkine/CX3CL1 and RANTES/CCR5.

immunology↗

bioRxiv2020

Behaviour of two species of psittacine birds, Crimson Rosella Platycercus elegans and Australian King-Parrot Alisterus scapularis, at wild bird feeding sites in Australia

This study investigated how Crimson Rosellas Platycercus elegans (CR) and Australian King-Parrots Alisterus scapularis (AKP) used provisioned seed at two public bird feeding sites in Australia. A total of 197 CR and 72 AKP were trapped and colour-banded. Observational data was collected every 10mins between 08:00-16:00 for three consecutive days during autumn and spring. Foraging effort was described using five metrics that quantified the birds visiting frequency and foraging duration over each day and observation period. Seed selection (over 5mins) and intake (over 10mins) were determined, and the energy intake was calculated. Total counts and population estimates were calculated for each species. Individual, species, seasonal and geographic variation in the use of provisioned seed was demonstrated by the metric summaries and Restricted Maximum Likelihood Modelling. Both species fed as part of large mixed species flocks that would not naturally congregate together to forage. Overall, CR were found to have higher foraging effort and feed in greater numbers than AKP, but a spectrum of use was observed for both species. Individuals were observed using the provisioned seed between 0-3 days/observation period. When birds used the provisioned seed, they were found to make between 1-8 visits/day, with most lasting 10-30mins. Few daily durations lasted longer than 50mins. Within a 10-minute interval, it was possible for a CR and AKP to obtain between 1.73-62.91% and 6.84-88.54% of their daily energy requirements, respectively. In a visit, either species could fill their crop and meet most, if not all, of their daily energy requirements. A small percentage of birds (6.5%) were found to use the feeding sites daily and for long durations (up to 160mins). It is likely that a proportion of the birds using the provisioned seed at both sites were dependent on the food source and would be at risk if the seed supply were suddenly reduced. The study also provided evidence that wild bird feeding provided an advantage to one or more species, as well as evidence that the food source did not affect the study species seasonal dispersal patterns or juveniles ability to forage on natural food sources.

ecology↗

bioRxiv2019

Evaluating the stoichiometric trait distributions of cultured bacterial populations and uncultured microbial communities

Originality StatementThe ecological stoichiometry of microbial biomass has most often focused on the ratio of the biologically-important elements carbon (C), nitrogen (N), and phosphorus (P) and has primarily been examined at a resolution where the contribution of the individual is masked by the reported population or community average. However, reporting population or community averages makes it difficult to assess phenotypic plasticity and stochasticity and mask important information required to understand both the drivers and implications of microbial biomass stoichiometry in nature. One way to assess the diversity of individual microbial phenotypes is through the use of single-cell techniques such as energy dispersive spectroscopy (EDS). EDS reports cellular quotas for the majority of elements composing microbial biomass including C, N, and P. In this study, by measuring individual cells within a microbial community or population, we describe for the first time the stoichiometry of microbial biomass as a distribution instead of an average. Exploration of stoichiometric trait distributions (as presented here) has the potential to improve our understanding of how nutrients interact with individual microorganisms to structure the elemental content of bacterial biomass and better describe how bacterial community biomass affects the ecosystems within which these organisms exist. SummaryTo assess the potential for EDS to describe the stoichiometric variance within populations and communities we measured the stoichiometric trait distribution of cultured freshwater bacterial populations under different resource conditions and compared them to natural microbial communities sampled from three lakes. Mean biomass C:N:P values obtained by EDS matched closely to those obtained by bulk measures using traditional analytical techniques for each freshwater isolate. However, we observed pronounced differences in the stoichiometric trait distributions of freshwater bacterial isolates compared to the stoichiometric trait distributions of natural communities. The stoichiometric trait distribution of the environmental isolates changed with P availability, growth phase, and genotype, with P availability having the strongest effect. The distribution of biomass ratios within each isolate growth experiment were the most constrained during stages of rapid growth and commonly had unimodal distributions. In contrast to the population distributions, the distribution of N:P and C:P for a similar number of cells from each of the mixed lake communities had narrower stoichiometric distributions and more commonly exhibited multiple modes.

ecology↗

bioRxiv2017

Linking the chemistry and reactivity of dissolved organic matter from low-latitude glaciers and rock glaciers

As glaciers thaw in response to warming, they release dissolved organic matter (DOM) to alpine lakes and streams. The United States contains an abundance of both alpine glaciers and rock glaciers. Differences in DOM composition and bioavailability between glacier types, like rock and ice glaciers, remain undefined. To assess differences in glacier and rock glacier DOM we evaluated bioavailability and molecular composition of DOM from four alpine catchments each with a glacier and a rock glacier at their headwaters. We assessed bioavailability of DOM by incubating each DOM source with a common microbial community and evaluated chemical characteristics of DOM before and after incubation using untargeted gas chromatography mass spectrometry based metabolomics (GC-MS). Prior to incubations, ice glacier and rock glacier DOM had similar C:N ratios and chemical diversity, but differences in DOM composition. Incubations with a common microbial community showed DOM from ice glacier meltwaters contained a higher proportion of bioavailable DOM (BDOM) and resulted in greater bacterial growth efficiency (BGE). After incubation, DOM composition from each source was statistically indistinguishable. This study provides an example of how MS based metabolomics can be used to assess effects of DOM composition on differences in bioavailability of DOM. Furthermore, it illustrates the importance of microbial metabolism in structuring composition of DOM. Even though rock glaciers had significantly less BDOM than ice glaciers, both glacial types still have potential to be important sources of BDOM to alpine headwaters over the coming decades.\n\nKey PointsBioavailability of organic matter released from glaciers is greater than that of rock glaciers in the Rocky Mountains.\n\nThe use of GC-MS for ecosystem metabolomics represents a novel approach for examining complex organic matter pools.\n\nBoth glaciers and rock glaciers supply highly bioavailable sources of organic matter to alpine headwaters in Colorado.

ecology↗