Toxoplasma gondii infection reduces predator aversion in rats through epigenetic modulation in the host medial amygdala

Male rats (Rattus novergicus) infected with protozoan Toxoplasma gondii relinquish their innate aversion to the cat odours. This behavioural change is postulated to increase transmission of the parasite to its definitive felid hosts. Here, we show that the Toxoplasma gondii infection institutes an epigenetic change in the DNA methylation of the arginine vasopressin promoter in the medial amygdala of male rats. Infected animals exhibit hypomethylation of arginine vasopressin promoter, leading to greater expression of this nonapeptide. The infection also results in the greater activation of the vasopressinergic neurons after exposure to the cat odour. Furthermore, we show that loss of fear in the infected animals can be rescued by the systemic hypermethylation and recapitulated by directed hypomethylation in the medial amygdala. These results demonstrate an epigenetic proximate mechanism underlying the extended phenotype in the Rattus novergicus–Toxoplasma gondii association.     

The parasite's long arm: a tapeworm parasite induces behavioural changes in uninfected group members of its social host

Parasites can induce alterations in host phenotypes in order to enhance their own survival and transmission. Parasites of social insects might not only benefit from altering their individual hosts, but also from inducing changes in uninfected group members. Temnothorax nylanderi ant workers infected with the tapeworm Anomotaenia brevis are known to be chemically distinct from nest-mates and do not contribute to colony fitness, but are tolerated in their colonies and well cared for. Here, we investigated how tapeworm- infected workers affect colony aggression by manipulating their presence in ant colonies and analysing whether their absence or presence resulted in behavioural alterations in their nest-mates. We report a parasite-induced shift in colony aggression, shown by lower aggression of uninfected nest-mates from parasitized colonies towards conspecifics, potentially explaining the tolerance towards infected ants. We also demonstrate that tapeworm-infected workers showed a reduced flight response and higher survival, while their presence caused a decrease in survival of uninfected nest-mates. This anomalous behaviour of infected ants, coupled with their increased survival, could facilitate the parasites'' transmission to its definitive hosts, woodpeckers. We conclude that parasites exploiting individuals that are part of a society not only induce phenotypic changes within their individual hosts, but in uninfected group members as well.     

A lost cause? Fundamental problems for causal theories of parenthood

In this paper, I offer a critique of (actual and possible) causal theories of parenthood. I do not offer a competing account of who incurs parental obligations and why; rather, I aim to show that there are fundamental problems for any account of who acquires parental obligations and why by appeal to causal responsibility for a child’s existence. I outline and justify three criteria that any plausible causal account of parental obligation must meet, and demonstrate that attempting to fulfil all three criteria simultaneously will give rise to one or both of two potentially insurmountable dilemmas.     

India's E‐Waste Rules and Their Impact on E‐Waste Management Practices: A Case Study

India, like many other developed and developing countries, has adopted an extended producer responsibility (EPR) approach for electronic waste (e‐waste) management under its E‐waste (Management and Handling) Rules, 2011. Under these rules, producers have been made responsible for setting up collection centers of e‐waste and financing and organizing a system for environmentally sound management of e‐waste. In this article, we use the implementation of these rules in Ahmedabad in western India as a case study to conduct a critical analysis of the implementation of India's Rules. Interviews of main stakeholder groups, including a sample of regulated commercial establishments, regulatory agencies enforcing the Rules, informal actors involved in waste collection and handling, as well as publicly available information on the implementation constitute data for our case study. Our results indicate that while there has been an increase in the formal waste processing capacity after the implementation of the Rules, only 5% to 15% of the total waste generated is likely channeled through formal processing facilities. While the EPR regulation forced the producers to take action on a few relatively inexpensive aspects of the Rules, the collection and recycling system has not been made convenient for the consumers to deposit e‐waste in formal collection and recycling centers. Based on our findings, we argue that Indian EPR regulation should go beyond simple take‐back mandates and consider implementing other policy instruments such as a deposit‐refund system. An important implication for developing countries is the need for careful attention to instrument choice and design within EPR regulations.     

Survival of the feces: Does a nematode lungworm adaptively manipulate the behavior of its cane toad host?

Parasites can enhance their fitness by modifying the behavior of their hosts in ways that increase rates of production and transmission of parasite larvae. We used an antihelminthic drug to experimentally alter infections of lungworms (Rhabdias pseudosphaerocephala) in cane toads (Rhinella marina). We then compared subsequent behaviors of dewormed toads versus toads that retained infections. Both in the laboratory and in the field, the presence of parasites induced hosts to select higher body temperatures (thereby increasing rates of lungworm egg production), to defecate in moister sites, and to produce feces with higher moisture content (thereby enhancing survival of larvae shed in feces). Because those behavioral modifications enhance rather than decrease parasite fitness, they are likely to have arisen as adaptive manipulations of host behavior rather than as host adaptations to combat infection or as nonadaptive consequences of infection on host physiology. However, the mechanisms by which lungworms alter cane toad thermal preference and defecation are not known. Although many examples of host manipulation by parasites involve intermediate hosts facilitating their own demise, our findings indicate that manipulation of definitive hosts can be as subtle as when and where to defecate.     

INTERACTING PHENOTYPES AND THE EVOLUTIONARY PROCESS: I. DIRECT AND INDIRECT GENETIC EFFECTS OF SOCIAL INTERACTIONS

Interacting phenotypes are traits whose expression is affected by interactions with conspecifics. Commonly-studied interacting phenotypes include aggression, courtship, and communication. More extreme examples of interacting phenotypes—traits that exist exclusively as a product of interactions—include social dominance, intraspecific competitive ability, and mating systems. We adopt a quantitative genetic approach to assess genetic influences on interacting phenotypes. We partition genetic and environmental effects so that traits in conspecifics that influence the expression of interacting phenotypes are a component of the environment. When the trait having the effect is heritable, the environmental influence arising from the interaction has a genetic basis and can be incorporated as an indirect genetic effect. However, because it has a genetic basis, this environmental component can evolve. Therefore, to consider the evolution of interacting phenotypes we simultaneously consider changes in the direct genetic contributions to a trait (as a standard quantitative genetic approach would evaluate) as well as changes in the environmental (indirect genetic) contribution to the phenotype. We then explore the ramifications of this model of inheritance on the evolution of interacting phenotypes. The relative rate of evolution in interacting phenotypes can be quite different from that predicted by a standard quantitative genetic analysis. Phenotypic evolution is greatly enhanced or inhibited depending on the nature of the direct and indirect genetic effects. Further, unlike most models of phenotypic evolution, a lack of variation in direct genetic effects does not preclude evolution if there is genetic variance in the indirect genetic contributions. The available empirical evidence regarding the evolution of behavior expressed in interactions, although limited, supports the predictions of our model.     

What to do about fraud charges in science; or, will the Burt affair ever end?

Shortly after the death, in 1971, of Cyril Burt, a prominent British psychologist, the authenticity of his accounts of intelligence test results from the largest reported sample of MZA's (monozygotic twins reared apart) was challenged. Charges of fraud by Burt's critics and countercharges by his supporters started an acrimonious battle of words in journals, books, and the mass media that seesawed over the decades. It is still not resolved. The problematic ways in which the scientific community and its major organizations and journal editors have dealt or failed to deal with the problem are discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Some history of heredity-vs-environment, genetic inferiority at Harvard(?), and The (incredible) Bell Curve

This article discusses some historical and intellectual roots of American behaviorism in psychology and its anti-heredity, environmentalist bias, as well as the early ‘justification’ for pure line theory in genetics and some interrelations between the two fields. Next, I discuss the heritability concept, its promotion, its critique and the importance of distinguishing it from, rather than confusing or conflating it with, the heredity concept. Then, briefly I consider some of the history and problems associated with the intelligence concept, as well as the capital importance of biological controls in studies of human heredity. And finally, I document the incredibility of The Bell Curve and the appalling inadequacy of its reception. This revised version was published online in August 2006 with corrections to the Cover Date.     

Comparison of rates of fecal colonization with extended‐spectrum beta‐lactamase‐producing enterobacteria among patients in different wards,outpatients and medical students

Because asymptomatic carriage of extended‐spectrum beta‐lactamase (ESBL) producers is a risk factor for infection, data on colonization dynamics are important when planning infection control. This study investigated fecal colonization with ESBL producers among inpatients, outpatients and medical students and compares the characteristics of ESBL producers among these groups. Carriage rates were investigated in 5581 fecal samples; 4343 from inpatients (330, 1397, 619 and 1864 from adult ICUs [intensive care units], adult non‐ICUs, pediatric ICUs and pediatric non‐ICUs, respectively), 814 from outpatients and 424 from screening of medical students. ESBL producers were characterized by co‐resistance, integrons carried, and aminoglycoside resistance and ESBL genes. Dynamic regression models were built to identify relationships between combinations of time series of monthly antibiotic consumption, prevalence of carriers and infected subjects. Inpatients, ICU patients and adults showed higher prevalence than outpatients, non‐ICU patients or children (7.4%, 9.3% and 12.0% vs. 3.1%, 6.1% and 4.1%, respectively). Klebsiella pneumoniae was more frequent in ICU patients; dominance of CTX‐M‐15 producers was more marked in adult than in pediatric inpatients. ESBL carriage was shown to be a consequence of infection in adults in the time‐series analysis; antibiotic consumption had little effect. The epidemiology of colonization with ESBL producers differed between pediatric ICU, adult ICU and adult non‐ICU patients. In adults, carriage of ESBL producers seems to be the consequence of infection, especially in ICU patients; the main source of colonization is nosocomial acquisition. In contrast, children are less likely to acquire colonizer strains in hospitals; importation of ESBL producers by colonized children seems to be significant.     

Assessing the Greenhouse Gas Savings Potential of Extended Producer Responsibility for Mattresses and Boxsprings in the United States

Extended producer responsibility (EPR) legislation in the United States, which currently only exists on the state level, now includes three mattress EPR acts, which intend to shift the financial and operational burden of mattress end‐of‐life (EOL) management away from local and state government. It is important to keep in mind, however, that the original objective behind EPR is to reduce the environmental life cycle impacts of products. This article therefore quantifies the greenhouse gas (GHG) savings potential of mattress and boxspring recycling and reuse in the United States and also discusses labor implications and mattress design issues. We find that all three acts are unlikely to generate redesign incentives, but are expected to dramatically increase mattress collection and recycling. The collection and recycling of all 35 million EOL mattress and boxspring units estimated to reach the end of their lives in the United States every year would generate in the order of 10,000 jobs and GHG savings between 1 and 1.5 million metric tonnes.