Genomic variation in two gametocyte non-producing Plasmodium falciparum clonal lines.

BACKGROUND: Transmission of the malaria parasite Plasmodium falciparum from humans to the mosquito vector requires differentiation of a sub-population of asexual forms replicating within red blood cells into non-dividing male and female gametocytes. The nature of the molecular mechanism underlying this key differentiation event required for malaria transmission is not fully understood. METHODS: Whole genome sequencing was used to examine the genomic diversity of the gametocyte non-producing 3D7-derived lines F12 and A4. These lines were used in the recent detection of the PF3D7_1222600 locus (encoding PfAP2-G), which acts as a genetic master switch that triggers gametocyte development. RESULTS: The evolutionary changes from the 3D7 parental strain through its derivatives F12 (culture-passage derived cloned line) and A4 (transgenic cloned line) were identified. The genetic differences including the formation of chimeric var genes are presented. CONCLUSION: A genomics resource is provided for the further study of gametocytogenesis or other phenotypes using these parasite lines.

"Relational by Nature"? Men and Women Do Not Differ in Physiological Response to Social Stressors Faced by Token Women.

Women in male-dominated occupations report negative workplace social climates, whereas most men in female-dominated occupations report positive workplace social climates. Using a laboratory experiment mimicking the negative workplace social climates experienced by these token women, the author examines whether women are more sensitive to negative workplace social climates than men are or if, instead, men and women react similarly. Using salivary cortisol, the author finds that token men and token women are equally likely to exhibit a physiological stress response to social exclusion on the basis of gender. A second experiment shows that token men and token women who are socially included do not exhibit physiological stress response. Findings imply that(1) social exclusion on the basis of gender may be associated with physiological stress response and consequent negative health outcomes and (2) combined social-structural and social-interactional components of token women's workplace climates would be stressors to both men and women workers.

Stigma, status, and population health.

Stigma and status are the major concepts in two important sociological traditions that describe related processes but that have developed in isolation. Although both approaches have great promise for understanding and improving population health, this promise has not been realized. In this paper, we consider the applicability of status characteristics theory (SCT) to the problem of stigma with the goal of better understanding social systemic aspects of stigma and their health consequences. To this end, we identify common and divergent features of status and stigma processes. In both, labels that are differentially valued produce unequal outcomes in resources via culturally shared expectations associated with the labels; macro-level inequalities are enacted in micro-level interactions, which in turn reinforce macro-level inequalities; and status is a key variable. Status and stigma processes also differ: Higher- and lower-status states (e.g., male and female) are both considered normal, whereas stigmatized characteristics (e.g., mental illness) are not; interactions between status groups are guided by "social ordering schemas" that provide mutually agreed-upon hierarchies and interaction patterns (e.g., men assert themselves while women defer), whereas interactions between "normals" and stigmatized individuals are not so guided and consequently involve uncertainty and strain; and social rejection is key to stigma but not status processes. Our juxtaposition of status and stigma processes reveals close parallels between stigmatization and status processes that contribute to systematic stratification by major social groupings, such as race, gender, and SES. These parallels make salient that stigma is not only an interpersonal or intrapersonal process but also a macro-level process and raise the possibility of considering stigma as a dimension of social stratification. As such, stigma's impact on health should be scrutinized with the same intensity as that of other more status-based bases of stratification such as SES, race and gender, whose health impacts have been firmly established.

Physiological stress response to loss of social influence and threats to masculinity.

Social influence is an important component of contemporary conceptualizations of masculinity in the U.S. Men who fail to achieve masculinity by maintaining social influence in the presence of other men may be at risk of stigmatization. As such, men should be especially likely to exhibit a stress response to loss of social influence in the presence of other men. This study assesses whether men who lose social influence exhibit more of a stress response than men who gain social influence, using data collected in a laboratory setting where participants were randomly assigned into four-person groups of varying sex compositions. The groups were videotaped working on two problem-solving tasks. Independent raters assessed change in social influence using a well-validated measure borrowed from experimental work in the Status Characteristics Theory tradition. Cortisol is used as a measure of stress response because it is known to increase in response to loss of social esteem. Results show that young men who lose social influence while working with other young men exhibit cortisol response. In contrast women do not exhibit cortisol response to loss of social influence, nor do men working with women. Results are consistent with the hypothesis that loss of social influence in men may be associated with a physiological stress response because maintaining social influence is very important to men while in the presence of other men. This physiological response to loss of social influence underscores the importance to men of achieving masculinity through gaining and maintaining social influence, and avoiding the stigma associated with the failure to do so.

Phenotypic variation of lipid composition in Burkholderia cepacia: a response to increased growth temperature is a greater content of 2-hydroxy acids in phosphatidylethanolamine and ornithine amide lipid.

Burkholderia cepacia produces an unusual range of polar lipids, which includes two forms each of phosphatidylethanolamine (PE) and ornithine amide lipid (OL), differing in the presence or absence of 2-hydroxy fatty acids. By using chemostat cultures in chemically defined media, variations in the lipid content and the proportions of individual lipids have been studied as a function of (a) growth temperature, (b) growth rate and (c) growth-limiting nutrient (carbon, magnesium, phosphorus or oxygen). Total cellular lipid in carbon-limited cultures was lowest at high growth temperatures and low growth rates. Increases in growth temperature over the range 25-40 degrees C led to increases in the proportions of molecular species of PE and OL containing 2-hydroxy acids, without changing the PE:OL ratio. Growth temperature did not alter the balance between neutral and acidic lipids, but the contribution of phosphatidylglycerol to the latter increased with rising growth temperature and growth rate. Pigmentation of cells and the presence of flagella were also temperature-dependent. Change in growth rate also affected the PE:OL ratio and the extent to which monoenoic acids were replaced by their cyclopropane derivatives. Whereas similar lipid profiles were found for carbon-, magnesium- and oxygen-limited cultures, ornithine amides were the only polar lipids detected in phosphorus-limited cells.