Gene–Environment Interactions at Nucleotide Resolution

Interactions among genes and the environment are a common source of phenotypic variation. To characterize the interplay between genetics and the environment at single nucleotide resolution, we quantified the genetic and environmental interactions of four quantitative trait nucleotides (QTN) that govern yeast sporulation efficiency. We first constructed a panel of strains that together carry all 32 possible combinations of the 4 QTN genotypes in 2 distinct genetic backgrounds. We then measured the sporulation efficiencies of these 32 strains across 8 controlled environments. This dataset shows that variation in sporulation efficiency is shaped largely by genetic and environmental interactions. We find clear examples of QTN:environment, QTN: background, and environment:background interactions. However, we find no QTN:QTN interactions that occur consistently across the entire dataset. Instead, interactions between QTN only occur under specific combinations of environment and genetic background. Thus, what might appear to be a QTN:QTN interaction in one background and environment becomes a more complex QTN:QTN:environment:background interaction when we consider the entire dataset as a whole. As a result, the phenotypic impact of a set of QTN alleles cannot be predicted from genotype alone. Our results instead demonstrate that the effects of QTN and their interactions are inextricably linked both to genetic background and to environmental variation.     

Are Free Radicals Involved in the Pathobiology of Human Essential Hypertension?

Possible involvement of reactive oxygen species and nitric oxide in the pathogenesis of human essential hypertension was investigated. It was observed that both superoxide anion and hydrogen peroxide production by polymorphonuclear leukocytes and the plasma levels of lipid peroxides are higher in uncontrolled essential hypertension compared with normal controls. Nitric oxide levels measured as its stable metabolite nitrite, as an index of nitric oxide synthesis, revealed its levels to be low in hypertensive patients. Superoxide anion, hydrogen peroxide, lipid peroxides and nitric oxide levels reverted to normal values after the control of hypertension by drugs. The concentrations of anti-oxidants such as vitamin E and superoxide dismutase were found to be decreased in patients with uncontrolled hypertension. Several anti-hypertensive drugs inhibited lipid peroxidation in vitro. Angiotensin-II, a potent vasoconstrictor, stimulated free radical generation in normal leukocytes which could be blocked by calmodulin antagonists. These results suggest that an increase in free radical generation and a simultaneous decrease in the production of nitric oxide and anti-oxidants such as SOD and vitamin E occurs in essential hypertension. This increase in free radical generation can inactivate prostacyclin and nitric oxide and decrease their half life which can lead to an increase in peripheral vascular resistance and hypertension.     

Trophic Garnishes: Cat–Rat Interactions in an Urban Environment

Background

Community interactions can produce complex dynamics with counterintuitive responses. Synanthropic community members are of increasing practical interest for their effects on biodiversity and public health. Most studies incorporating introduced species have been performed on islands where they may pose a risk to the native fauna. Few have examined their interactions in urban environments where they represent the majority of species. We characterized house cat (Felis catus) predation on wild Norway rats (Rattus norvegicus), and its population effects in an urban area as a model system. Three aspects of predation likely to influence population dynamics were examined; the stratum of the prey population killed by predators, the intensity of the predation, and the size of the predator population.

Methodology/Principal Findings

Predation pressure was estimated from the sizes of the rat and cat populations, and the characteristics of rats killed in 20 alleys. Short and long term responses of rat population to perturbations were examined by removal trapping. Perturbations removed an average of 56% of the rats/alley but had no negative long-term impact on the size of the rat population (49.6±12.5 rats/alley and 123.8±42.2 rats/alley over two years). The sizes of the cat population during two years (3.5 animals/alley and 2.7 animals/alley) also were unaffected by rat population perturbations. Predation by cats occurred in 9/20 alleys. Predated rats were predominantly juveniles and significantly smaller (144.6 g±17.8 g) than the trapped rats (385.0 g±135.6 g). Cats rarely preyed on the larger, older portion of the rat population.

Conclusions/Significance

The rat population appears resilient to perturbation from even substantial population reduction using targeted removal. In this area there is a relatively low population density of cats and they only occasionally prey on the rat population. This occasional predation primarily removes the juvenile proportion of the rat population. The top predator in this urban ecosystem appears to have little impact on the size of the prey population, and similarly, reduction in rat populations doesn''t impact the size of the cat population. However, the selected targeting of small rats may locally influence the size structure of the population which may have consequences for patterns of pathogen transmission.     

Socio-cultural Determinants of Human–Bat Interactions in Rural Ghana

Bats are known to be a natural reservoir for a lot of disease pathogens and can spread several diseases. All 11 genera of fruit bat found in West Africa are found in Ghana, and human–bat interactions are common. However, there is a dearth of knowledge about the socio-cultural factors that shape these interactions. This paper explores the socio-cultural factors that bring humans into contact with bats. Data were obtained through focus group discussions and in-depth interviews. The findings indicate that gender, religious affiliation, and belief systems influence the interaction between humans and bats. We conclude that the hunting and consumption patterns of bats have farreaching consequences for the transmission of bat-borne zoonotic diseases. Educational campaigns, therefore, should be intensified and, in particular, target groups that are most at risk of contracting bat-borne zoonotic diseases.     

Plant–Environment Interactions in the Low Arctic Torngat Mountains of Labrador

Ecosystems - The eastern Canadian Subarctic and Arctic are experiencing significant environmental change with widespread implications for the people, plants, and animals living there. In this...     

Why Do People Laugh during Dog–Human Play Interactions?

Given that human laughter has been posited to signal playfulness to dogs, nonserious social incongruity, and positive affect, laughter should occur during incongruous contexts in an affectively positive, nonserious social activity such as dog–human play. A total of 116 laughs in relation to dogs were discerned on videotapes of 46 dog–human play interactions in the US, 23 with familiar and 23 with unfamiliar pairs. Laughter occurred during 61% of interactions, and always expressed positive affect. Contexts in which laughter occurred (in decreasing frequency) were failure of the dog during play, or to play at all or as the person wanted; exaggerated or unexpected engagement by the dog; excretion; unexpected success by the dog in obtaining an object; and, once, threat from the dog. Laughter never induced play, and usually occurred when a dog was not playing. Women laughed more than men, especially for a male audience when playing with their own dog. In all contexts, participants experienced incongruous events; contexts were nonserious, except for the dog's threat, where laughter signaled friendliness. These data are largely consistent with laughter signaling positive affect and awareness of (usually nonserious) social incongruity, and inconsistent with laughter signaling playfulness to dogs.     

Human IgG/FcγR Interactions Are Modulated by Streptococcal IgG Glycan Hydrolysis

Background

The human pathogen Streptococcus pyogenes produces an endoglycosidase, EndoS that hydrolyzes the chitobiose core of the asparagine-linked glycan on the heavy chain of human IgG. IgG-binding to Fc gamma receptors (FcγR) on leukocytes triggers effector functions including phagocytosis, oxidative burst and the release of inflammatory mediators. The interactions between FcγR and the Fc domain of IgG depend on the IgG glycosylation state.

Methodology/Principal Findings

Here we show for the first time that EndoS hydrolyzes the heavy chain glycan of all four human IgG subclasses (IgG1-4), in purified form and in a plasma environment. An inactive form of EndoS, obtained by site-directed mutagenesis, binds IgG with high affinity, in contrast to wild type EndoS that only transiently interacts with IgG, as shown by Slot-blotting and surface plasmon resonance technology. Furthermore, EndoS hydrolysis of the IgG glycan influences the binding of IgG to immobilized soluble FcγR and to an erythroleukemic cell line, K562, expressing FcγRIIa. Incubation of whole blood with EndoS results in a dramatic decrease of IgG binding to activated monocytes as analyzed by flow cytometry. Moreover, the IgG bound to K562 cells dissociates when cells are treated with EndoS. Likewise, IgG bound to immobilized FcγRIIa and subsequently treated with EndoS, dissociates from the receptor as analyzed by surface plasmon resonance and Western blot.

Conclusions/Significance

We provide novel information about bacterial enzymatic modulation of the IgG/FcγR interaction that emphasizes the importance of glycosylation for antibody effector functions. Moreover, EndoS could be used as a biochemical tool for specific IgG N-glycan hydrolysis and IgG purification/detection, or as a potential immunosuppressing agent for treatment of antibody-mediated pathological processes.     

Breaking Through Disciplinary Barriers: Human–Wildlife Interactions and Multispecies Ethnography

One of the main challenges when integrating biological and social perspectives in primatology is overcoming interdisciplinary barriers. Unfamiliarity with subject-specific theory and language, distinct disciplinary-bound approaches to research, and academic boundaries aimed at “preserving the integrity” of subject disciplines can hinder developments in interdisciplinary research. With growing interest in how humans and other primates share landscapes, and recognition of the importance of combining biological and social information to do this effectively, the disparate use of terminology is becoming more evident. To tackle this problem, we dissect the meaning of what the biological sciences term studies in “human–wildlife conflict” or more recently “human–wildlife interactions” and compare it to what anthropology terms “multispecies ethnography.” In the biological sciences, human–wildlife interactions are the actions resulting from people and wild animals sharing landscapes and resources, with outcomes ranging from being beneficial or harmful to one or both species. In the social sciences, human–nonhuman relationships have been explored on a philosophical, analytical, and empirical level. Building on previous work, we advocate viewing landscapes through an interdisciplinary “multispecies lens” in which humans are observed as one of multiple organisms that interact with other species to shape and create environments. To illustrate these interconnections we use the case study of coexistence between people of the Nalu ethnic group and Critically Endangered western chimpanzees (Pan troglodytes verus) at Cantanhez National Park in Guinea-Bissau, to demonstrate how biological and social research approaches can be complementary and can inform conservation initiatives at the human–primate interface. Finally, we discuss how combining perspectives from ethnoprimatology with those from multispecies ethnography can advance the study of ethnoprimatology to aid productive discourse and enhance future interdisciplinary research.     

Transgene × Environment Interactions in Genetically Modified Wheat

Background

The introduction of transgenes into plants may cause unintended phenotypic effects which could have an impact on the plant itself and the environment. Little is published in the scientific literature about the interrelation of environmental factors and possible unintended effects in genetically modified (GM) plants.

Methods and Findings

We studied transgenic bread wheat Triticum aestivum lines expressing the wheat Pm3b gene against the fungus powdery mildew Blumeria graminis f.sp. tritici. Four independent offspring pairs, each consisting of a GM line and its corresponding non-GM control line, were grown under different soil nutrient conditions and with and without fungicide treatment in the glasshouse. Furthermore, we performed a field experiment with a similar design to validate our glasshouse results.The transgene increased the resistance to powdery mildew in all environments. However, GM plants reacted sensitive to fungicide spraying in the glasshouse. Without fungicide treatment, in the glasshouse GM lines had increased vegetative biomass and seed number and a twofold yield compared with control lines. In the field these results were reversed. Fertilization generally increased GM/control differences in the glasshouse but not in the field. Two of four GM lines showed up to 56% yield reduction and a 40-fold increase of infection with ergot disease Claviceps purpurea compared with their control lines in the field experiment; one GM line was very similar to its control.

Conclusions

Our results demonstrate that, depending on the insertion event, a particular transgene can have large effects on the entire phenotype of a plant and that these effects can sometimes be reversed when plants are moved from the glasshouse to the field. However, it remains unclear which mechanisms underlie these effects and how they may affect concepts in molecular plant breeding and plant evolutionary ecology.     

Implications of Tourist–Macaque Interactions for Disease Transmission

During wildlife tourism, proximity or actual contact between people and animals may lead to a significant risk of anthropozoonotic disease transmission. In this paper, we use social network analysis, disease simulation modelling and data on animal health and behaviour to investigate such risks at a site in Morocco, where tourists come to see wild Barbary macaques (Macaca sylvanus). Measures of individual macaques’ network centrality—an index of the strength and distribution of their social relationships and thus potentially their ability to spread disease—did not show clear and consistent relationships with their time spent in close proximity to, or rate of interacting with, tourists. Disease simulation modelling indicated that while higher-ranked animals had a significantly greater ability to spread disease within the group, in absolute terms there was little difference in the size of outbreaks that different individuals were predicted to cause. We observed a high rate of physical contact and close proximity between humans and macaques, including during three periods when the macaques were coughing and sneezing heavily, highlighting the potential risk of disease transmission. We recommend that general disease prevention strategies, such as those aimed at reducing opportunities for contact between tourists and macaques, should be adopted.     

Human–Wildlife Interactions Predict Febrile Illness in Park Landscapes of Western Uganda

Fevers of unknown origin complicate treatment and prevention of infectious diseases and are a global health burden. We examined risk factors of self-reported fever—categorized as “malarial” and “nonmalarial”—in households adjacent to national parks across the Ugandan Albertine Rift, a biodiversity and emerging infectious disease hotspot. Statistical models fitted to these data suggest that perceived nonmalarial fevers of unknown origin were associated with more frequent direct contact with wildlife and with increased distance from parks where wildlife habitat is limited to small forest fragments. Perceived malarial fevers were associated with close proximity to parks but were not associated with direct wildlife contact. Self-reported fevers of any kind were not associated with livestock ownership. These results suggest a hypothesis that nonmalarial fevers in this area are associated with wildlife contact, and further investigation of zoonoses from wildlife is warranted. More generally, our findings of land use–disease relationships aid in hypothesis development for future research in this social-ecological system where emerging infectious diseases specifically, and rural public health provisioning generally, are important issues.