Proceedings of the Academy of Natural Sciences of Philadelphia.

v.72 (1920)

Loss of social behaviors by Myxococcus xanthus during evolution in an unstructured habitat

Social behaviors are often targets of natural selection among higher organisms, but quantifying the effects of such selection is difficult. We have used the bacterium Myxococcus xanthus as a model system for studying the evolution of social interactions. Changes in the social behaviors of 12 M. xanthus populations were quantified after 1,000 generations of evolution in a liquid habitat, in which interactions among individuals were continually hindered by shaking and low cell densities. Derived lineages were compared with their ancestors with respect to maximum growth rate, motility rates on hard and soft agar, fruiting body formation ability, and sporulation frequency during starvation. Improved performance in the liquid selective regime among evolved lines was usually associated with significant reductions in all of the major social behaviors of M. xanthus. Maintenance of functional social behaviors is apparently detrimental to fitness under asocial growth conditions.

Genetic control of social organization in an ant

A central issue in evolutionary biology is the extent to which complex social organization is under genetic control. We have found that a single genomic element marked by the protein-encoding gene Gp-9 is responsible for the existence of two distinct forms of social organization in the fire ant Solenopsis invicta. This genetic factor influences the reproductive phenotypes and behavioral strategies of queens and determines whether workers tolerate a single fertile queen or multiple queens per colony. Furthermore, this factor affects worker tolerance of queens with alternate genotypes, thus explaining the dramatic differences in Gp-9 allele frequencies observed between the two social forms in the wild. These findings reveal how a single genetic factor can have major effects on complex social behavior and influence the nature of social organization.

HIV-1 and T cell dynamics after interruption of highly active antiretroviral therapy (HAART) in patients with a history of sustained viral suppression

Identifying the immunologic and virologic consequences of discontinuing antiretroviral therapy in HIV-infected patients is of major importance in developing long-term treatment strategies for patients with HIV-1 infection. We designed a trial to characterize these parameters after interruption of highly active antiretroviral therapy (HAART) in patients who had maintained prolonged viral suppression on antiretroviral drugs. Eighteen patients with CD4+ T cell counts ≥ 350 cells/μl and viral load below the limits of detection for ≥1 year while on HAART were enrolled prospectively in a trial in which HAART was discontinued. Twelve of these patients had received prior IL-2 therapy and had low frequencies of resting, latently infected CD4 cells. Viral load relapse to >50 copies/ml occurred in all 18 patients independent of prior IL-2 treatment, beginning most commonly during weeks 2–3 after cessation of HAART. The mean relapse rate constant was 0.45 (0.20 log10 copies) day−1, which was very similar to the mean viral clearance rate constant after drug resumption of 0.35 (0.15 log10 copies) day−1 (P = 0.28). One patient experienced a relapse delay to week 7. All patients except one experienced a relapse burden to >5,000 RNA copies/ml. Ex vivo labeling with BrdUrd showed that CD4 and CD8 cell turnover increased after withdrawal of HAART and correlated with viral load whereas lymphocyte turnover decreased after reinitiation of drug treatment. Virologic relapse occurs rapidly in patients who discontinue suppressive drug therapy, even in patients with a markedly diminished pool of resting, latently infected CD4+ T cells.

Genetics and the population history of Europe

Analysis of genetic variation among modern individuals is providing insight into prehistoric events. Comparisons of levels and patterns of genetic diversity with the predictions of models based on archeological evidence suggest that the spread of early farmers from the Levant was probably the main episode in the European population history, but that both older and more recent processes have left recognizable traces in the current gene pool.

A long marine history of carbon cycle modulation by orbital-climatic changes

Pacing of the marine carbon cycle by orbital forcing during the Pliocene and Pleistocene Ice Ages [past 2.5 million years (Myr)] is well known. As older deep-sea sediment records are being studied at greater temporal resolution, it is becoming clear that similar fluctuations in the marine carbon system have occurred throughout the late Mesozoic and Tertiary, despite the absence of large continental ice sheets over much of this time. Variations in both the organic and the calcium carbonate components of the marine carbon system seem to have varied cyclically in response to climate forcing, and carbon and carbonate time series appear to accurately characterize the frequency spectrum of ancient climatic change. For the past 35 Myr, much of the variance in carbonate content carries the “polar” signal of obliquity [41,000 years (41 kyr)] forcing. Over the past 125 Myr, there is evidence from marine sediments of the continued role of precessional (≈21 kyr) climatic cycles. Repeat patterns of sedimentation at about 100, 400, and 2,400 kyr, the modulation periods of precession, persistently enter into marine carbon cycle records as well. These patterns suggest a nonlinear response of climate and/or the sedimentation of organic carbon and carbonates to precessional orbital perturbations. Nonlinear responses of the carbon system may help to amplify relatively weak orbital insolation anomalies into more significant climatic perturbations through positive feedback effects. Nonlinearities in the carbon cycle may have transformed orbital-climatic cycles into long-wavelength features on time scales comparable to the residence times of carbon and nutrient elements in the ocean.

Acting White Among Black College Students: A Phenomenological Study of Social Constructions of Race

This study was a qualitative examination of Black college students' experiences with the Acting White label. In conducting this study, two gaps in literature were addressed: (1) the lack of literature on Black college students and the acting white label, and (2) lack of attention to a US racial history and current structures which allow a label such as "acting white" to exist. Thus, the purpose of this study was to call attention to the experiences of Black college students as it relates to the acting white label. Additionally, the study calls attention to social constructions that allow the acting white label to exist and to be sustained. Data was collected from 14 Black college students at a predominantly white, private, liberal arts university in the west. Based on responses from students in the study, Black college students do hear that they are acting white. Yet, their reaction to hearing the label does not cause them to underachieve academically, but does have an impact on their social actions. The ways in which Black college students in the study were labeled as acting white was based on academic pursuits, speech patterns, dress, and hobbies. Student reactions to the label ranged from ignoring the label to challenging the accuser. In regards to how the acting white label is sustained, students in the study expressed that they learned what it meant to act white or black from family interactions, social interactions and observations from family and friends, and from media sources. It was concluded that Black college students, despite reactions, do hear the label and that the label seems to be used as a means to attack Black students and their identity.

History of health, a valuable tool in public health

The aim of this article is to highlight the importance of the history of public health for public health research and practice itself. After summarily reviewing the current great vitality of the history of collective health oriented initiatives, we explain three particular features of the historical vantage point in public health, namely the importance of the context, the relevance of a diachronic attitude and the critical perspective. In order to illustrate those three topics, we bring up examples taken from three centuries of fight against malaria, the so called “re-emerging diseases” and the 1918 influenza epidemic. The historical approach enriches our critical perception of the social effects of initiatives undertaken in the name of public health, shows the shortcomings of public health interventions based on single factors and asks for a wider time scope in the assessment of current problems. The use of a historical perspective to examine the plurality of determinants in any particular health condition will help to solve the longlasting debate on the primacy of individual versus population factors, which has been particularly intense in recent times.

An Architecture by means of Anthropology. Beyond learning the tools of social science

Los arquitectos y urbanistas tienen una larga tradición en el aprendizaje de las herramientas de las ciencias sociales, especialmente las que les permiten analizar y describir mejor los entornos y las personas para las que trabajan. Esto ha llevado a los arquitectos a desarrollar mejores herramientas de observación y descripción del ámbito social y no sólo el material. Sin embargo, la mayoría de las veces este acercamiento interdisciplinar ha identificado las ciencias sociales, especialmente la antropología, con la etnografía. Este artículo parte de la crítica a esta identificación hecha por el antropólogo Tim Ingold y se centra en lo que él propone como el método central de la antropología, la observación participante. Para después revisar varias propuestas actuales de científicos sociales que tratan de desarrollar una disciplina no representacional y orientada al futuro, un objetivo más cercano al de la arquitectura. El artículo intenta imaginar cómo esta práctica transdisciplinar podría desarrollarse.

Bulletin of the Buffalo Society of Natural Sciences.

v. 5 (1886-97)

American spiders and their spinningwork. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits. By Henry C. McCook.

v.2 1890

American spiders and their spinningwork. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits. By Henry C. McCook.

v.3 1893

Archives of science and transactions of the Orleans County Society of Natural Sciences.

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