Methodologies and special considerations for environmental risk analysis of genetically modified aquatic biocontrol organisms

Genetic biocontrol of invasive aquatic species proposes to introduce, for control purposes, a genetically modified (GM) version of an invasive fish species to a targeted aquatic environment. Safe deployment and long term use of such technologies will depend on identifying and managing possible unintended effects to the natural environment. Environmental risk analysis (ERA) is a method for identifying the likelihood and consequences of unintended impacts, and for developing risk management strategies. For the unique situation of genetically modified biocontrol organisms (GMBOs), we review the latest thinking in ERA methodologies for GM fish and explore how terminology and assumptions from ERAs of traditional, non-modified biocontrol organisms and GM fish will need to be recast in ERAs of GMBOs. We also outline some special considerations that an ERA of a GMBOs will have to contend with: non-intuitive potential hazards; uncertainty introduced by extrapolating from domestic systems to natural ecosystems; redundancy in risk management options; and challenges of stakeholder engagement related to new technologies.     

Chemical Validation of Trypanothione Synthetase: A POTENTIAL DRUG TARGET FOR HUMAN TRYPANOSOMIASIS*

In the search for new therapeutics for the treatment of human African trypanosomiasis, many potential drug targets in Trypanosoma brucei have been validated by genetic means, but very few have been chemically validated. Trypanothione synthetase (TryS; EC 6.3.1.9; spermidine/glutathionylspermidine:glutathione ligase (ADP-forming)) is one such target. To identify novel inhibitors of T. brucei TryS, we developed an in vitro enzyme assay, which was amenable to high throughput screening. The subsequent screen of a diverse compound library resulted in the identification of three novel series of TryS inhibitors. Further chemical exploration resulted in leads with nanomolar potency, which displayed mixed, uncompetitive, and allosteric-type inhibition with respect to spermidine, ATP, and glutathione, respectively. Representatives of all three series inhibited growth of bloodstream T. brucei in vitro. Exposure to one of our lead compounds (DDD86243; 2 × EC₅₀ for 72 h) decreased intracellular trypanothione levels to <10% of wild type. In addition, there was a corresponding 5-fold increase in the precursor metabolite, glutathione, providing strong evidence that DDD86243 was acting on target to inhibit TryS. This was confirmed with wild-type, TryS single knock-out, and TryS-overexpressing cell lines showing expected changes in potency to DDD86243. Taken together, these data provide initial chemical validation of TryS as a drug target in T. brucei.     

Factors Influencing In Vitro Killing of Bacteria by Hemocytes of the Eastern Oyster (Crassostrea virginica)

A tetrazolium dye reduction assay was used to study factors governing the killing of bacteria by oyster hemocytes. In vitro tests were performed on bacterial strains by using hemocytes from oysters collected from the same location in winter and summer. Vibrio parahaemolyticus strains, altered in motility or colonial morphology (opaque and translucent), and Listeria monocytogenes mutants lacking catalase, superoxide dismutase, hemolysin, and phospholipase activities were examined in winter and summer. Vibrio vulnificus strains, opaque and translucent (with and without capsules), were examined only in summer. Among V. parahaemolyticus and L. monocytogenes, significantly (P < 0.05) higher levels of killing by hemocytes were observed in summer than in winter. L. monocytogenes was more resistant than V. parahaemolyticus or V. vulnificus to the bactericidal activity of hemocytes. In winter, both translucent strains of V. parahaemolyticus showed significantly (P < 0.05) higher susceptibility to killing by hemocytes than did the wild-type opaque strain. In summer, only one of the V. parahaemolyticus translucent strains showed significantly (P < 0.05) higher susceptibility to killing by hemocytes than did the wild-type opaque strain. No significant differences (P > 0.05) in killing by hemocytes were observed between opaque (encapsulated) and translucent (nonencapsulated) pairs of V. vulnificus. Activities of 19 hydrolytic enzymes were measured in oyster hemolymph collected in winter and summer. Only one enzyme, esterase (C4), showed a seasonal difference in activity (higher in winter than in summer). These results suggest that differences existed between bacterial genera in their ability to evade killing by oyster hemocytes, that a trait(s) associated with the opaque phenotype may have enabled V. parahaemolyticus to evade killing by the oyster’s cellular defense, and that bactericidal activity of hemocytes was greater in summer than in winter.     

Evaluation of facial cleanliness and environmental improvement activities: Lessons learned from Malawi,Tanzania, and Uganda

The World Health Organization promotes the SAFE (Surgery, Antibiotics, Facial cleanliness, and Environmental improvements) strategy for trachoma control and prevention. The F&E components of the strategy focus on promotion of healthy hygiene and sanitation behaviors. In order to monitor F&E activities implemented across villages and schools in Malawi, Tanzania, and Uganda, an F&E Monitoring and Evaluation (FEME) framework was developed to track quarterly program outputs and to provide the basis for a pre and post evaluation of the activities. Results showed an increase in knowledge at the school and household levels, and in some cases, an increase in presence of hand/face washing stations. However, this did not always result in a change in trachoma prevention behaviors such as facial cleanliness or keeping compounds free of human feces. The results highlight that the F&E programs were effective in increasing awareness of trachoma prevention but not able to translate that knowledge into changes in behavior during the time between pre and post-surveys. This study also indicates the potential to improve the data collection and survey design and notes that the period of intervention was not long enough to measure significant changes.     

On the origin of membrane vesicles in Gram-negative bacteria

It is proposed that the genesis of extracellular membrane vesicles in Gram-negative bacteria is a result of cell wall turnover. Peptidoglycan turnover would cause a turgor on the outer membrane, causing the outer membrane to bulge and finally bleb. Mechanical motion would then shear the blebs into the culture medium.     

Plant-based diets and incident cardiovascular disease and all-cause mortality in African Americans: A cohort study

BackgroundPrior studies have documented lower cardiovascular disease (CVD) risk among people with a higher adherence to a plant-based dietary pattern. Non-Hispanic black Americans are an understudied group with high burden of CVD, yet studies of plant-based diets have been limited in this population.Methods and findingsWe conducted an analysis of prospectively collected data from a community-based cohort of African American adults (n = 3,635) in the Jackson Heart Study (JHS) aged 21–95 years, living in the Jackson, Mississippi, metropolitan area, US, who were followed from 2000 to 2018. Using self-reported dietary data, we assigned scores to participants’ adherence to 3 plant-based dietary patterns: an overall plant-based diet index (PDI), a healthy PDI (hPDI), and an unhealthy PDI (uPDI). Cox proportional hazards models were used to estimate associations between plant-based diet scores and CVD incidence and all-cause mortality. Over a median follow-up of 13 and 15 years, there were 293 incident CVD cases and 597 deaths, respectively. After adjusting for sociodemographic characteristics (age, sex, and education) and health behaviors (smoking, alcohol intake, margarine intake, physical activity, and total energy intake), no significant association was observed between plant-based diets and incident CVD for overall PDI (hazard ratio [HR] 1.06, 95% CI 0.78–1.42, p-trend = 0.72), hPDI (HR 1.07, 95% CI 0.80–1.42, p-trend = 0.67), and uPDI (HR 0.95, 95% CI 0.71–1.28, p-trend = 0.76). Corresponding HRs (95% CIs) for all-cause mortality risk with overall PDI, hPDI, and uPDI were 0.96 (0.78–1.18), 0.94 (0.76–1.16), and 1.06 (0.86–1.30), respectively. Corresponding HRs (95% CIs) for incident coronary heart disease with overall PDI, hPDI, and uPDI were 1.09 (0.74–1.61), 1.11 (0.76–1.61), and 0.79 (0.52–1.18), respectively. For incident total stroke, HRs (95% CIs) for overall PDI, hPDI, and uPDI were 1.00 (0.66–1.52), 0.91 (0.61–1.36), and 1.26 (0.84–1.89) (p-trend for all tests > 0.05). Limitations of the study include use of self-reported dietary intake, residual confounding, potential for reverse causation, and that the study did not capture those who exclusively consume plant-derived foods.ConclusionsIn this study of black Americans, we observed that, unlike in prior studies, greater adherence to a plant-based diet was not associated with CVD or all-cause mortality.

In a cohort study, Leah J. Weston and colleagues investigate the associations between consumption of plant-based diets and incident cardiovascular disease and all-cause mortality in African Americans.     

Influence of inoculum morphology on growth of Atropa belladonna hairy roots and production of tropane alkaloids

Summary The specific growth rate of Atropa belladonna hairy roots measured in terms of root length increased by about 25% to 0.49 d^-1 when the inoculum consisted of a root with the primary root tip excised. The biomass dry weight produced after 14 d increased by 28%. In contrast, presence of laterals in the inoculum with or without lateral tips excised did not influence the growth rate. Although hyoscyamine was found to accumulate at higher concentrations in the more mature root tissues (2.1 ± 0.2 mg g^-1) than in the tips (1.1 ± 0.3 mg g^-1), hyoscyamine content in the harvested roots was independent of inoculum morphology.     

Collective decision‐making and fission–fusion dynamics: a conceptual framework

Sociality exists in an extraordinary range of ecological settings. For individuals to accrue the benefits associated with social interactions, they are required to maintain a degree of spatial and temporal coordination in their activities, and make collective decisions. Such coordination and decision‐making has been the focus of much recent research. However, efforts largely have been directed toward understanding patterns of collective behaviour in relatively stable and cohesive groups. Less well understood is how fission–fusion dynamics mediate the process and outcome of collective decisions making. Here, we aim to apply established concepts and knowledge to highlight the implications of fission–fusion dynamics for collective decisions, presenting a conceptual framework based on the outcome of a small‐group discussion INCORE meeting (funded by the European Community's Sixth Framework Programme). First, we discuss how the degree of uncertainty in the environment shapes social flexibility and therefore the types of decisions individuals make in different social settings. Second, we propose that the quality of social relationships and the energetic needs of each individual influence fission decisions. Third, we explore how these factors affect the probability of individuals to fuse. Fourth, we discuss how group size and fission–fusion dynamics may affect communication processes between individuals at a local or global scale to reach a consensus or to fission. Finally, we offer a number of suggestions for future research, capturing emerging ideas and concepts on the interaction between collective decisions and fission–fusion dynamics.