Effects of body size,diet, and transience on the demography of the arboreal boid snake Corallus grenadensis on Carriacou (Grenada Grenadines,West Indies)

Remarkably little is known about the demography of snakes in the family Boidae. This lack of information may be attributed, in part, to low population densities on the Neotropical mainland, rendering capture-recapture methods impractical for many species. Conversely, islands support fewer species but snake densities can be much higher. Corallus grenadensis is an arboreal boid endemic to the Grenada Bank and, relative to mainland boids, can be amazingly abundant. As young, its diet is comprised largely of native Anolis lizards, a ubiquitous and abundant food source; it then undergoes an ontogenetic shift in diet to a less abundant resource, rodents. From 2015 to 2019, we marked 254 C. grenadensis and used capture–recapture models to estimate abundance, capture probabilities, survival, and the proportion of transients. We hypothesized that the transient effect would increase with body size (snout–vent length [SVL]), prompted by their ontogenetic shift in diet. Capture probabilities increased with sampling effort and decreased with increasing SVL. Abundance ranged from 96 to 141 individuals and annual resident survival was 0.71, 95% confidence interval (CI) = 0.54–0.83. The proportion of transients increased with increasing SVL, with the estimate being distinguishable from zero starting at ~810 mm SVL, coinciding with the size at which their dietary shift from ectothermic to endothermic prey begins. Ontogenetic dietary shifts are widespread in snakes and occur in at least 11 of 17 species of West Indian boids. Thus, the prominence of transients in our study may be indicative of its demographic and ecological importance among other snake species.     

Rapid,reliable, and reproducible cell fusion assay to quantify SARS-Cov-2 spike interaction with hACE2

COVID-19 is a global crisis of unimagined dimensions. Currently, Remedesivir is only fully licensed FDA therapeutic. A major target of the vaccine effort is the SARS-CoV-2 spike-hACE2 interaction, and assessment of efficacy relies on time consuming neutralization assay. Here, we developed a cell fusion assay based upon spike-hACE2 interaction. The system was tested by transient co-transfection of 293T cells, which demonstrated good correlation with standard spike pseudotyping for inhibition by sera and biologics. Then established stable cell lines were very well behaved and gave even better correlation with pseudotyping results, after a short, overnight co-incubation. Results with the stable cell fusion assay also correlated well with those of a live virus assay. In summary we have established a rapid, reliable, and reproducible cell fusion assay that will serve to complement the other neutralization assays currently in use, is easy to implement in most laboratories, and may serve as the basis for high throughput screens to identify inhibitors of SARS-CoV-2 virus-cell binding and entry.     

夏天我们去了森林 回到自然的孩子们

目前,并不是所有生活在大城市里的年轻人都有较长的时间去亲近大自然、感受自然母亲的温暖。对于城市青年来说,森林、河流、湿地、草原和野生动植物是在画中,在电影或电视中,甚至是在电脑的游戏里。然而,纽约一所高中的学生们,却能在每年夏天痛痛快快地丢开地铁、电视和iPod,用一个月的时间到自然保护区去进行实地考察。也许读者没有想过"触摸自然"对于认知世界是多么     

Fusobacterium nucleatum in periodontal health and disease

The pathogenesis of periodontitis involves the interplay of microbiota present in the subgingival plaque and the host responses. Inflammation and destruction of periodontal tissues are considered to result from the response of a susceptible host to a microbial biofilm containing gram-negative pathogens. Antimicrobial peptides are important contributors to maintaining the balance between health and disease in this complex environment. These include several salivary antimicrobial peptides such as β-defensins expressed in the epithelium and LL-37 expressed in both epithelium and neutrophils. Among gram-negative bacteria implicated in periodontal diseases, Fusobacterium nucleatum, is one of the most interesting. This review will focus on expression, function, regulation and functional efficacy of antimicrobial peptides against F. nucleatum. We are looking for how the presence of F. nucleatum induces secretion of peptides which have an impact on host cells and modulate immune response.     

Assessing vegetation condition in temperate montane grasslands

Rapid assessment techniques are commonly used for measuring vegetation condition at sites. Techniques for measuring site condition need to be quantitative, repeatable, rapid and simple. The key challenge is achieving a balance between simple techniques and adequate discrimination of condition between sites. This study compared a grassland condition index with the existing BioMetric condition index and showed that (i) the grassland index provided a strong measure of the relationship of temperate montane grassland sites with disturbance level, and differentiated condition of sites to a high degree and (ii) the simpler BioMetric index provided a strong measure of the relationship of the grassland sites with disturbance and differentiated their condition to a moderate degree. The choice of index to assess grassland condition should depend on purpose, cost and capacity.     

Intradermal injections of equine allogeneic umbilical cord-derived mesenchymal stem cells are well tolerated and do not elicit immediate or delayed hypersensitivity reactions

BACKGROUND AIMS. The use of allogeneic mesenchymal stem cells (MSC) to treat acute equine lesions would greatly expand equine cellular therapy options; however, the safety and antigenicity of these cells have not been well-studied. We hypothesized that equine allogeneic umbilical cord tissue (UCT)-derived MSC would not elicit acute graft rejection or a delayed-type hypersensitivity response when injected intradermally. METHODS. Six Quarterhorse yearlings received 12 intradermal injections (autologous MSC, allogeneic MSC, positive control and negative control, in triplicate) followed by the same series of 12 injections, 3-4 weeks later, at another site. Wheals were measured and palpated at 0.25, 4, 24, 48, 72 h and 7 days post-injection. Biopsies were obtained at 48 and 72 h and 7 days post-injection. Mixed leukocyte reactions were performed 1 week prior to the first injections and 3 weeks after the second injections. RESULTS. There were no adverse local or systemic responses to two intradermal injections of allogeneic MSC. MSC injection resulted in minor wheal formation, characterized by mild dermatitis, dermal edema and endothelial hyperplasia, that fully resolved by 48-72 h. No differences were noted between allogeneic and autologous MSC. The second injection of MSC did not elicit more significant physical or histomorphologic alterations compared with the first MSC injection. Neither allogeneic nor autologous UCT-derived MSC stimulated or suppressed baseline T-cell proliferation in vitro prior to or after two MSC administrations. CONCLUSIONS. Equine allogeneic UCT MSC may be safely administered intradermally on multiple occasions without eliciting a measurable cellular immune response.     

Structure and function of BamE within the outer membrane and the β-barrel assembly machine

Insertion of folded proteins into the outer membrane of Gram-negative bacteria is mediated by the essential β-barrel assembly machine (Bam). Here, we report the native structure and mechanism of a core component of this complex, BamE, and show that it is exclusively monomeric in its native environment of the periplasm, but is able to adopt a distinct dimeric conformation in the cytoplasm. BamE is shown to bind specifically to phosphatidylglycerol, and comprehensive mutagenesis and interaction studies have mapped key determinants for complex binding, outer membrane integrity and cell viability, as well as revealing the role of BamE within the Bam complex.