Natural variation in life history and aging phenotypes is associated with mitochondrial DNA deletion frequency in Caenorhabditis briggsae

<p>Abstract</p> <p>Background</p> <p>Mutations that impair mitochondrial functioning are associated with a variety of metabolic and age-related disorders. A barrier to rigorous tests of the role of mitochondrial dysfunction in aging processes has been the lack of model systems with relevant, naturally occurring mitochondrial genetic variation. Toward the goal of developing such a model system, we studied natural variation in life history, metabolic, and aging phenotypes as it relates to levels of a naturally-occurring heteroplasmic mitochondrial <it>ND5 </it>deletion recently discovered to segregate among wild populations of the soil nematode, <it>Caenorhabditis briggsae</it>. The normal product of <it>ND5 </it>is a central component of the mitochondrial electron transport chain and integral to cellular energy metabolism.</p> <p>Results</p> <p>We quantified significant variation among <it>C. briggsae </it>isolates for all phenotypes measured, only some of which was statistically associated with isolate-specific <it>ND5 </it>deletion frequency. We found that fecundity-related traits and pharyngeal pumping rate were strongly inversely related to <it>ND5 </it>deletion level and that <it>C. briggsae </it>isolates with high <it>ND5 </it>deletion levels experienced a tradeoff between early fecundity and lifespan. Conversely, oxidative stress resistance was only weakly associated with <it>ND5 </it>deletion level while ATP content was unrelated to deletion level. Finally, mean levels of reactive oxygen species measured <it>in vivo </it>showed a significant non-linear relationship with <it>ND5 </it>deletion level, a pattern that may be driven by among-isolate variation in antioxidant or other compensatory mechanisms.</p> <p>Conclusions</p> <p>Our findings suggest that the <it>ND5 </it>deletion may adversely affect fitness and mitochondrial functioning while promoting aging in natural populations, and help to further establish this species as a useful model for explicit tests of hypotheses in aging biology and mitochondrial genetics.</p

Black Like Malcolm: Grace Halsell’s Rewriting of Black Like Me (1961) in Soul Sister (1969)

This essay compares Grace Halsell’s under-examined and now out-of-print memoir Soul Sister (1969) to its precursor, John Howard Griffin’s Black Like Me (1961), in order to demonstrate that Halsell attempts to revise Black Like Me’s focus on a portrait of black powerlessness, pathos, and lack of voice. While Griffin evacuates political context, Halsell fills her text with male and female voices from the Civil Rights and Black Power Movements; in so doing she forwards a multivalent and plural construct of black subjectivity and black political struggle. Ultimately, Halsell depicts herself moving into the political subjectivity of Malcolm X, although she also reaches towards what she sees as his final vision in which a stark black-white racial binary is transcended. Second, the essay also argues that at key junctures Halsell’s text turns back onto itself as an exploration of the formation of white racial identity as well as the privileges according to white femininity; the intersectional oppression she experiences while passing forces her to interrogate the construction of categories not only of race, but also of sex and class. Taken together, these texts therefore enable an examination of what is at stake in the genre of the white passing narrative—as well as why the modes of looking at blackness present in these texts so often fail. While the genre of the white passing narrative has been critically derided, this essay seeks to show that such works allow an examination of the formation and transformation of categories of white racial (and to a lesser extent) gendered identity, as well as the way whiteness remains the fulcrum of personal, social, and political privilege

An Interview with Martha J. Cutter, editor of MELUS

NANO assistant editor Rebecca Devers interviews Martha J. Cutter, the former editor of MELUS, about the complexities of processing, reviewing, and publishing a journal that receives in over 300 submissions each year. An Interview with Martha J. Cutter, editor of MELUS by Rebecca Devers