The effect of D-xylose, beta-D-xylosides and beta-D-galactosides on chondroitin sulphate biosynthesis in embryonic chicken cartilage.

The incorporation of [3H]acetate into chondroitin sulphate was used as a measure of the rate of synthesis of this polysaccharide in whole tibias and femurs of embryonic chicken cartilage in vitro. The incorporation is inhibited by puromycin and by cycloheximide, but the inhibition is relieved by the addition of D-xylose, beta-D-xylosides and beta-D-galactosides to the incubation medium. Beta-D-Xylosides can stimulate the incorporation to 300% of that of controls incubated in the absence of cycloheximide or puromycin, D-Xylose, beta-D-xylosides and beta-D-galactosides appear to act as artificial initiators of chondroitin sulphate synthesis and enable polysaccharide-chain synthesis to be studied as an event separate from the synthesis of intact proteoglycan.     

Integration of Vibrio vulnificus into Marine Aggregates and Its Subsequent Uptake by Crassostrea virginica Oysters

Marine aggregates are naturally forming conglomerations of larvacean houses, phytoplankton, microbes, and inorganics adhered together by exocellular polymers. In this study, we show in vitro that the bacterial pathogen Vibrio vulnificus can be concentrated into laboratory-generated aggregates from surrounding water. We further show that environmental (E-genotype) strains exhibit significantly more integration into these aggregates than clinical (C-genotype) strains. Experiments where marine aggregates with attached V. vulnificus cells were fed to oysters (Crassostrea virginica) resulted in greater uptake of both C and E types than nonaggregated controls. When C- and E-genotype strains were cocultured in competitive experiments, the aggregated E-genotype strains exhibited significantly greater uptake by oyster than the C-genotype strains.     

Life‐history constraints in grassland plant species: a growth‐defence trade‐off is the norm

Plant growth can be limited by resource acquisition and defence against consumers, leading to contrasting trade‐off possibilities. The competition‐defence hypothesis posits a trade‐off between competitive ability and defence against enemies (e.g. herbivores and pathogens). The growth‐defence hypothesis suggests that strong competitors for nutrients are also defended against enemies, at a cost to growth rate. We tested these hypotheses using observations of 706 plant populations of over 500 species before and following identical fertilisation and fencing treatments at 39 grassland sites worldwide. Strong positive covariance in species responses to both treatments provided support for a growth‐defence trade‐off: populations that increased with the removal of nutrient limitation (poor competitors) also increased following removal of consumers. This result held globally across 4 years within plant life‐history groups and within the majority of individual sites. Thus, a growth‐defence trade‐off appears to be the norm, and mechanisms maintaining grassland biodiversity may operate within this constraint.     

Evidence runs contrary to digestive stability predicting protein allergenicity

Transgenic Research - A dogma has persisted for over two decades that food allergens are more stable to digestion compared with non-allergenic proteins. This belief has become enshrined in...     

The effectiveness of flower strips and hedgerows on pest control,pollination services and crop yield: a quantitative synthesis

Floral plantings are promoted to foster ecological intensification of agriculture through provisioning of ecosystem services. However, a comprehensive assessment of the effectiveness of different floral plantings, their characteristics and consequences for crop yield is lacking. Here we quantified the impacts of flower strips and hedgerows on pest control (18 studies) and pollination services (17 studies) in adjacent crops in North America, Europe and New Zealand. Flower strips, but not hedgerows, enhanced pest control services in adjacent fields by 16% on average. However, effects on crop pollination and yield were more variable. Our synthesis identifies several important drivers of variability in effectiveness of plantings: pollination services declined exponentially with distance from plantings, and perennial and older flower strips with higher flowering plant diversity enhanced pollination more effectively. These findings provide promising pathways to optimise floral plantings to more effectively contribute to ecosystem service delivery and ecological intensification of agriculture in the future.     

Synchronous biological feedbacks in parrotfishes associated with pantropical coral bleaching

Biological feedbacks generated through patterns of disturbance are vital for sustaining ecosystem states. Recent ocean warming and thermal anomalies have caused pantropical episodes of coral bleaching, which has led to widespread coral mortality and a range of subsequent effects on coral reef communities. Although the response of many reef‐associated fishes to major disturbance events on coral reefs is negative (e.g., reduced abundance and condition), parrotfishes show strong feedbacks after disturbance to living reef structure manifesting as increases in abundance. However, the mechanisms underlying this response are poorly understood. Using biochronological reconstructions of annual otolith (ear stone) growth from two ocean basins, we tested whether parrotfish growth was enhanced following bleaching‐related coral mortality, thus providing an organismal mechanism for demographic changes in populations. Both major feeding guilds of parrotfishes (scrapers and excavators) exhibited enhanced growth of individuals after bleaching that was decoupled from expected thermal performance, a pattern that was not evident in other reef fish taxa from the same environment. These results provide evidence for a more nuanced ecological feedback system—one where disturbance plays a key role in mediating parrotfish–benthos interactions. By influencing the biology of assemblages, disturbance can thereby stimulate change in parrotfish grazing intensity and ultimately reef geomorphology over time. This feedback cycle operated historically at within‐reef scales; however, our results demonstrate that the scale, magnitude, and severity of recent thermal events are entraining the biological responses of disparate communities to respond in synchrony. This may fundamentally alter feedbacks in the relationships between parrotfishes and reef systems.     

Impacts of predator-mediated interactions along a climatic gradient on the population dynamics of an alpine bird

According to classic theory, species'' population dynamics and distributions are less influenced by species interactions under harsh climatic conditions compared to under more benign climatic conditions. In alpine and boreal ecosystems in Fennoscandia, the cyclic dynamics of rodents strongly affect many other species, including ground-nesting birds such as ptarmigan. According to the ‘alternative prey hypothesis’ (APH), the densities of ground-nesting birds and rodents are positively associated due to predator–prey dynamics and prey-switching. However, it remains unclear how the strength of these predator-mediated interactions change along a climatic harshness gradient in comparison with the effects of climatic variation. We built a hierarchical Bayesian model to estimate the sensitivity of ptarmigan populations to interannual variation in climate and rodent occurrence across Norway during 2007–2017. Ptarmigan abundance was positively linked with rodent occurrence, consistent with the APH. Moreover, we found that the link between ptarmigan abundance and rodent dynamics was strongest in colder regions. Our study highlights how species interactions play an important role in population dynamics of species at high latitudes and suggests that they can become even more important in the most climatically harsh regions.     

Generation of APOE knock-down SK-N-SH human neuroblastoma cells using CRISPR/Cas9: a novel cellular model relevant to Alzheimer’s disease research

APOE ε4 is the major genetic risk factor for Alzheimer’s disease (AD). A precise role for apolipoprotein E (apoE) in the pathogenesis of the disease remains unclear in part due to its expression in multiple cell types of the brain. APOE is highly expressed in astrocytes and microglia, however its expression can also be induced in neurons under various conditions. The neuron-like cell line SK-N-SH is a useful model in the study of the cellular and molecular effects of apoE as it can be differentiated with retinoic acid to express and secrete high levels of apoE and it also shows the same apoE fragmentation patterns observed in the human brain. We previously found that apoE is cleaved into a 25-kDa fragment by high temperature-requirement serine protease A1 (HtrA1) in SK-N-SH cells. To further understand the endogenous functions of apoE, we used CRISPR/Cas9 to generate SK-N-SH cell lines with APOE expression knocked-down (KD). APOE KD cells showed lower APOE and HTRA1 expression than parental SK-N-SH cells but no overt differences in neuritogenesis or cell proliferation compared with the CRISPR/Cas9 control cells. This research shows that the loss of apoE and HtrA1 has a negligible effect on neuritogenesis and cell survival in SK-N-SH neuron-like cells.     

Focus: Preventive Medicine: Undiagnosed Hypertension and Undiagnosed Type 2 Diabetes among Overweight and Obese Marshallese Participants in a Diabetes Prevention Program

Hypertension and type 2 diabetes (T2D) are major public health issues that disproportionately affect minority communities, including Native Hawaiians and Pacific Islanders (NHPI). Minority communities are also more likely to have undiagnosed hypertension and T2D. Marshallese Pacific Islanders have been shown to have high proportions of diagnosed and undiagnosed hypertension and T2D. Using survey and biometric data collected from 378 overweight/obese Marshallese Pacific Islander adults, this study documents the prevalence of hypertension and T2D, as well as the prevalence of undiagnosed hypertension and T2D. The study also examines associations between undiagnosed hypertension and undiagnosed T2D and age group, sex, health care access (defined by foregone care due to cost and health insurance status), and body mass index (BMI). Among participants with blood pressure readings indicative of hypertension, 68.4% were undiagnosed, and among participants with HbA1c indicative of T2D, 31.6% were undiagnosed. A quarter of participants (24.5%) had blood pressure and HbA1c measures indicative of both undiagnosed hypertension and undiagnosed T2D. Undiagnosed hypertension was significantly associated with age group (p’s<0.0001) and sex (p=0.028). Undiagnosed T2D was significantly associated with age group (p’s<0.05), forgone care due to cost (p=0.018), health insurance status (p=0.035), and BMI (p=0.001). Participants in this study had high proportions of undiagnosed hypertension and undiagnosed T2D. These findings will be immediately useful for those working to address hypertension and T2D disparities among Marshallese and other NHPI populations.