The evolution of vertebrate eye size across an environmental gradient: phenotype does not predict genotype in a Trinidadian killifish

Vertebrates exhibit substantial variation in eye size. Eye size correlates positively with visual capacity and behaviors that enhance fitness, such as predator avoidance. This foreshadows a connection between predation and eye size evolution. Yet, the conditions that favor evolutionary shifts in eye size, besides the well‐known role for light availability, are unclear. We tested the influence of predation on the evolution of eye size in Trinidadian killifish, Rivulus hartii. Rivulus are located across a series of communities where they coexist with visually oriented piscivores ("high predation" sites), and no predators (“Rivulus‐only” sites). Wild‐caught Rivulus from high predation sites generally exhibited a smaller relative eye size than communities that lack predators. Yet, such differences were inconsistent across rivers. Second‐generation common garden reared fish revealed repeatable decreases in eye size in Rivulus from high predation sites. We performed additional experiments that tested the importance of light and resources on eye size evolution. Sites that differ in light or resource availability did not differ in eye size. Our results argue that differences in predator‐induced mortality underlie genetically‐based shifts in vertebrate eye size. We discuss the drivers of eye size evolution in light of the nonparallel trends between the phenotypic and common garden results.     

The Assimilation of Western Medicine into a Semi-nomadic Healthcare System: A Case Study of the Indigenous Aeta Magbukún,Philippines

The Aeta Magbukún are a genetically and culturally distinct group of Indigenous people living in an isolated mountain forest in the municipality of Mariveles, in the province of Bataan, Philippines. This research aims to document some healthcare related information of the people, inform future decisions regarding maximising benefits of modern conveniences, and minimise negative consequences on their culture and health. Using an ethnographic approach, data were collated from a community health survey in combination with field notes from three of the co-authors while living with the Aetas. Despite major implications from rapid ecological and cultural changes, traditional ethnomedical systems continue to be revered as an essential healing practice, although they are increasingly used in conjunction with Western medicines and healthcare. At the Aeta village level, the changing socio-political influence among the kagun (traditional healer), the NGOs, and the Municipal Council in terms of healthcare provision is pivotal, as the kagun has chosen to integrate the Western medicine and healthcare services into their traditional healthcare system, without simply rejecting them. In turn, Western-style healthcare interventions have the potential to be carefully managed to integrate traditional Aeta Magbukún socio-political structures, healthcare, and cultural continuity. The cumulative influence of numerous other novel aspects to Aeta life (e.g., permanent housing, a highway through the village, literacy, cash economies, energy-dense foods, communication/entertainment devices, etc.) will place additional pressure on the traditional ethnomedical healthcare system. However, enabling the continuity of access to appropriate healthcare knowledge (both the transfer of knowledge from Western medicine to the Aeta Magbukún, and vice versa) can assist many cultures through the inherent stresses of increasingly rapid acculturation and development.     

Parameter Identification in a Generalized Time-Harmonic Rayleigh Damping Model for Elastography

The identifiability of the two damping components of a Generalized Rayleigh Damping model is investigated through analysis of the continuum equilibrium equations as well as a simple spring-mass system. Generalized Rayleigh Damping provides a more diversified attenuation model than pure Viscoelasticity, with two parameters to describe attenuation effects and account for the complex damping behavior found in biological tissue. For heterogeneous Rayleigh Damped materials, there is no equivalent Viscoelastic system to describe the observed motions. For homogeneous systems, the inverse problem to determine the two Rayleigh Damping components is seen to be uniquely posed, in the sense that the inverse matrix for parameter identification is full rank, with certain conditions: when either multi-frequency data is available or when both shear and dilatational wave propagation is taken into account. For the multi-frequency case, the frequency dependency of the elastic parameters adds a level of complexity to the reconstruction problem that must be addressed for reasonable solutions. For the dilatational wave case, the accuracy of compressional wave measurement in fluid saturated soft tissues becomes an issue for qualitative parameter identification. These issues can be addressed with reasonable assumptions on the negligible damping levels of dilatational waves in soft tissue. In general, the parameters of a Generalized Rayleigh Damping model are identifiable for the elastography inverse problem, although with more complex conditions than the simpler Viscoelastic damping model. The value of this approach is the additional structural information provided by the Generalized Rayleigh Damping model, which can be linked to tissue composition as well as rheological interpretations.     

Dietary Plasticity of Generalist and Specialist Ungulates in the Namibian Desert: A Stable Isotopes Approach

Desert ungulates live in adverse ecosystems that are particularly sensitive to degradation and global climate change. Here, we asked how two ungulate species with contrasting feeding habits, grazing gemsbok (Oryx g. gazella) and browsing springbok (Antidorcas marsupialis), respond to an increase in food availability during a pronounced rain period. We used a stable isotope approach to delineate the feeding habits of these two ungulates in the arid Kunene Region of Namibia. Our nineteen months field investigation included two time periods of drought when food availability for ungulates was lowest and an intermediate period with extreme, unusual rainfalls. We documented thirteen isotopically distinct food sources in the isotopic space of the study area. Our results indicated a relatively high dietary plasticity of gemsbok, which fed on a mixture of plants, including more than 30% of C3 plants during drought periods, but almost exclusively on C4 and CAM plant types when food was plentiful. During drought periods, the inferred gemsbok diets also consisted of up to 25% of Euphorbia damarana; an endemic CAM plant that is rich in toxic secondary plant compounds. In contrast, springbok were generalists, feeding on a higher proportion of C3 than C4/CAM plants, irrespective of environmental conditions. Our results illustrate two dietary strategies in gemsbok and springbok which enable them to survive and coexist in the hostile Kunene arid ecosystem.     

Randomised Controlled Double-Blind Non-Inferiority Trial of Two Antivenoms for Saw-Scaled or Carpet Viper (Echis ocellatus) Envenoming in Nigeria

Background

In West Africa, envenoming by saw-scaled or carpet vipers (Echis ocellatus) causes great morbidity and mortality, but there is a crisis in supply of effective and affordable antivenom (ISRCTN01257358).

Methods

In a randomised, double-blind, controlled, non-inferiority trial, “EchiTAb Plus-ICP” (ET-Plus) equine antivenom made by Instituto Clodomiro Picado was compared to “EchiTAb G” (ET-G) ovine antivenom made by MicroPharm, which is the standard of care in Nigeria and was developed from the original EchiTAb-Fab introduced in 1998. Both are caprylic acid purified whole IgG antivenoms. ET-G is monospecific for Echis ocellatus antivenom (initial dose 1 vial) and ET-Plus is polyspecific for E. ocellatus, Naja nigricollis and Bitis arietans (initial dose 3 vials). Both had been screened by pre-clinical and preliminary clinical dose-finding and safety studies. Patients who presented with incoagulable blood, indicative of systemic envenoming by E. ocellatus, were recruited in Kaltungo, north-eastern Nigeria. Those eligible and consenting were randomly allocated with equal probability to receive ET-Plus or ET-G. The primary outcome was permanent restoration of blood coagulability 6 hours after the start of treatment, assessed by a simple whole blood clotting test repeated 6, 12, 18, 24 and 48 hr after treatment. Secondary (safety) outcomes were the incidences of anaphylactic, pyrogenic and late serum sickness-type antivenom reactions.

Findings

Initial doses permanently restored blood coagulability at 6 hours in 161/194 (83.0%) of ET-Plus and 156/206 (75.7%) of ET-G treated patients (Relative Risk [RR] 1.10 one-sided 95% CI lower limit 1.01; P = 0.05). ET-Plus caused early reactions on more occasions than did ET-G [50/194 (25.8%) and 39/206 (18.9%) respectively RR (1.36 one-sided 95% CI 1.86 upper limit; P = 0.06). These reactions were classified as severe in 21 (10.8%) and 11 (5.3%) of patients, respectively.

Conclusion

At these doses, ET-Plus was slightly more effective but ET-G was slightly safer. Both are recommended for treating E. ocellatus envenoming in Nigeria.

Trial Registration

Current Controlled Trials ISRCTN01257358     

Schistosoma mansoni: biochemical characterization of lactate transporters or similar proteins

While in medium containing glucose, schistosomes exhibit homolactic fermentation. Accumulation of lactate acid in tissue fluid causes lowering of pH and a resultant inhibition of metabolic pathways. This requires lactate transporter protein in homolactic fermentors to facilitate the translocation of lactate(-) and [H(+)] across their plasma membrane. The ex-vivo experiment assessed lactic acid secretion by adult worms in absence and the presence of lactic acid transporter protein inhibitors. Phloretin and alpha-cyano-4-hydroxycinnamate caused a combined 25-35% inhibition of lactic acid secretion and probenecid increased this inhibition to 65% of control values. The removal of inhibitors resulted in 80% recovery of lactic acid secretion. In the in-vitro studies using vesicles isolated from adult worms and from schistosomula, the effects of phloretin and alpha-cyano-4-hydroxycinnamate were greater, each causing approximately 80% inhibition independently. The data obtained in this study demonstrate the presence of lactic acid transporters or similar proteins in Schistosoma mansoni.     

Safe biotechnology. Part 6. Safety assessment,in respect of human health,of microorganisms used in biotechnology

The assessment of microorganisms in respect to human health is an important step for the introduction of new natural and genetically modified production strains to biotechnology. This report outlines the potential hazards posed by industrial microorganisms, important considerations related to pathogenicity, such as routes and portals of entry into the human body, mechanisms of spread of biological material and a definition of pathogenicity.Furthermore the most important steps in the assessment of pathogenicity of unknown strains are described. A short overview on characterization and in vitro and in vivo tests is presented. The hazard related to allergens and toxic metabolites is reviewed and the choice of methods and the handling of strains with unknown potential are discussed.     

Rate, affinity and calcium dependence of nitric oxide synthase isoform binding to the primary physiological regulator calmodulin

Using interferometry-based biosensors the binding and release of endothelial and neuronal nitric oxide synthase (eNOS and nNOS) from calmodulin (CaM) was measured. In both isoforms, binding to CaM is diffusion limited and within approximately three orders of magnitude of the Smoluchowski limit imposed by orientation-independent collisions. This suggests that the orientation of CaM is facilitated by the charge arrays on the CaM-binding site and the complementary surface on CaM. Protein kinase C phosphorylation of eNOS T495, adjacent to the CaM-binding site, abolishes or greatly slows CaM binding. Kinases which increase the activity of eNOS did not stimulate the binding of CaM, which is already diffusion limited. The coupling of Ca(2+) binding and CaM/NOS binding equilibria links the affinity of CaM for NOS to the Ca(2+) dependence of CaM binding. Hence, changes in the Ca(2+) sensitivity of CaM binding always imply changes in the NOS-CaM affinity. It is possible, however, that in some regimes binding and activation are not synonymous, so that Ca(2+) sensitivity need not be tightly linked to CaM sensitivity of activation. This study is being extended using mutants to probe the roles of individual structural elements in binding and release.