SARS-CoV-2 Variant Pathogenesis Following Primary Infection and Reinfection in Syrian Hamsters.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19, has evolved into multiple variants. Animal models are important to understand variant pathogenesis, particularly for variants with mutations that have significant phenotypic or epidemiological effects. Here, cohorts of naive or previously infected Syrian hamsters (Mesocricetus auratus) were infected with variants to investigate viral pathogenesis and disease protection. Naive hamsters infected with SARS-CoV-2 variants had consistent clinical outcomes, tissue viral titers, and pathology, while hamsters that recovered from initial infection and were reinfected demonstrated less severe clinical disease and lung pathology than their naive counterparts. Males had more frequent clinical signs than females in most variant groups, but few sex variations in tissue viral titers and lung pathology were observed. These findings support the use of Syrian hamsters as a SARS-CoV-2 model and highlight the importance of considering sex differences when using this species. IMPORTANCE With the continued circulation and emergence of new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, understanding differences in the effects between the initial infection and a subsequent reinfection on disease pathogenesis is critical and highly relevant. This study characterizes Syrian hamsters as an animal model to study reinfection with SARS-CoV-2. Previous infection reduced the disease severity of reinfection with different SARS-CoV-2 variants.

Tardigrades of the Tree Canopy: Milnesium swansoni sp. nov. (Eutardigrada: Apochela: Milnesiidae) a new species from Kansas, U.S.A.

Milnesium swansoni sp. nov. is a new species of Eutardigrada described from the tree canopy in eastern Kansas, USA. This species within the order Apochela, family Milnesiidae, genus Milnesium is distinguished by its smooth cuticle, narrow buccal tube, four peribuccal lamellae, primary claws without accessory points, and a secondary claw configuration of [3-3]-[3-3]. The buccal tube appears to be only half the width of the nominal species Milnesium tardigradum for animals of similar body length. The species adds to the available data for the phylum, and raises questions concerning species distribution.

A jungle in there: bacteria in belly buttons are highly diverse, but predictable.

The belly button is one of the habitats closest to us, and yet it remains relatively unexplored. We analyzed bacteria and arachaea from the belly buttons of humans from two different populations sampled within a nation-wide citizen science project. We examined bacterial and archaeal phylotypes present and their diversity using multiplex pyrosequencing of 16S rDNA libraries. We then tested the oligarchy hypothesis borrowed from tropical macroecology, namely that the frequency of phylotypes in one sample of humans predicts its frequency in another independent sample. We also tested the predictions that frequent phylotypes (the oligarchs) tend to be common when present, and tend to be more phylogenetically clustered than rare phylotypes. Once rarefied to four hundred reads per sample, bacterial communities from belly buttons proved to be at least as diverse as communities known from other skin studies (on average 67 bacterial phylotypes per belly button). However, the belly button communities were strongly dominated by a few taxa: only 6 phylotypes occurred on >80% humans. While these frequent bacterial phylotypes (the archaea were all rare) are a tiny part of the total diversity of bacteria in human navels (<0.3% of phylotypes), they constitute a major portion of individual reads (~1/3), and are predictable among independent samples of humans, in terms of both the occurrence and evolutionary relatedness (more closely related than randomly drawn equal sets of phylotypes). Thus, the hypothesis that "oligarchs" dominate diverse assemblages appears to be supported by human-associated bacteria. Although it remains difficult to predict which species of bacteria might be found on a particular human, predicting which species are most frequent (or rare) seems more straightforward, at least for those species living in belly buttons.

Plant science in forest canopies--the first 30 years of advances and challenges (1980-2010).

As an emerging subdiscipline of forest biology, canopy science has undergone a transition from observational, 'oh-wow' exploration to a more hypothesis-driven, experimental arena for rigorous field biology. Although efforts to explore forest canopies have occurred for a century, the new tools to access the treetops during the past 30 yr facilitated not only widespread exploration but also new discoveries about the complexity and global effects of this so-called 'eighth continent of the planet'. The forest canopy is the engine that fixes solar energy in carbohydrates to power interactions among forest components that, in turn, affect regional and global climate, biogeochemical cycling and ecosystem services. Climate change, biodiversity conservation, fresh water conservation, ecosystem productivity, and carbon sequestration represent important components of forest research that benefit from access to the canopy for rigorous study. Although some canopy variables can be observed or measured from the ground, vertical and horizontal variation in environmental conditions and processes within the canopy that determine canopy-atmosphere and canopy-forest floor interactions are best measured within the canopy. Canopy science has matured into a cutting-edge subset of forest research, and the treetops also serve as social and economic drivers for sustainable communities, fostering science education and ecotourism. This interdisciplinary context of forest canopy science has inspired innovative new approaches to environmental stewardship, involving diverse stakeholders.