Reciprocal TCR-CD3 and CD4 Engagement of a Nucleating pMHCII Stabilizes a Functional Receptor Macrocomplex

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Speed, Sex, Gay Men, and HIV: Ecological and Community Perspectives

Fifteen years into the HIV/AIDS epidemic, a great deal is now known about the different populations impacted by the disease, including those affected directly or indirectly by drug use. Anthropology has played a critical role in assisting with this task by identifying hidden populations, developing new methodological approaches, and targeting outreach efforts. In spite of this considerable body of ethnographic knowledge, men who have sex with other men (i.e., MSM, or gay and bisexual men) who use drugs have not received the same research attention as other drug users, despite the fact that they represent nearly one-fifth of AIDS cases in the U.S. with injection drug histories. In response to the alarming increase in HIV seroprevalence among this population, this ethnographic project provides preliminary data about those who are at dual risk for HIV through both homosexual behavior and injection drug use.     

Kainic Acid and Decorticating Lesions Stimulate the Synthesis of C1q Protein in Adult Rat Brain

Abstract: The first component of the classic complement cascade, C1q, was increased in whole rat brain after lesioning by intraperitoneally injected kainic acid (KA) (20-fold, 3 days after KA) and in the striatum ipsilateral to unilateral decortication (fivefold, 10 days after decortication). C1q was measured after purification by chromatography and electrophoresis. De novo biosynthesis of C1q 3 days after KA was increased >10-fold, as measured by the incorporation of [³⁵S]methionine into C1q after incubation of brain slices from KA-treated rats for 2 h. In parallel with these responses, KA induced fivefold increase of C1q bioactivity, as evaluated with C1q-dependent hemolysis. The contribution of C1q from entrapped cerebrovascular blood was evaluated by the effects of perfusion and was minor relative to the increases of C1q in response to KA lesioning. These findings support the hypothesis that the C1q protein detected by immunocytochemistry in senile plaques of Alzheimer brains and in the hippocampus after deafferenting lesions is synthesized by resident brain cells.     

Adult nutrition,but not inbreeding,affects male primary sexual traits in the leaf‐footed cactus bug Narnia femorata (Hemiptera: Coreidae)

Adverse conditions may be the norm rather than the exception in natural populations. Many populations experience poor nutrition on a seasonal basis. Further, brief interludes of inbreeding can be common as population density fluctuates and because of habitat fragmentation. Here, we investigated the effects of poor nutrition and inbreeding on traits that can be very important to reproductive success and fitness in males: testes mass, sperm concentration, and sperm viability. Our study species was Narnia femorata, a species introduced to north‐central Florida in the 1950s. This species encounters regular, seasonal changes in diet that can have profound phenotypic effects on morphology and behavior. We generated inbred and outbred individuals through a single generation of full‐sibling mating or outcrossing, respectively. All juveniles were provided a natural, high‐quality diet of Opuntia humifusa cactus cladode with fruit until they reached adulthood. New adult males were put on a high‐ or low‐quality diet for at least 21 days before measurements were taken. As expected, the low‐quality diet led to significantly decreased testes mass in both inbred and outbred males, although there were surprisingly no detectable effects on sperm traits. We did not find evidence that inbreeding affected testes mass, sperm concentration, and sperm viability. Our results highlight the immediate and overwhelming effects of nutrition on testes mass, while suggesting that a single generation of inbreeding might not be detrimental for primary sexual traits in this particular population.     

Neotropical Osmylidae larvae (Insecta,Neuroptera): description of habitats and morphology

ABSTRACT

The larval stages of the genus Kempynus Navás, 1912 Navás, L. (1912), ‘Insectos neurópteros nuevos o poco conocidos’, Memorias de la Real Academia de Ciencias y Artes de Barcelona, 10, 135–202. [Google Scholar] (probably K. falcatus Navás, 1912 Navás, L. (1912), ‘Insectos neurópteros nuevos o poco conocidos’, Memorias de la Real Academia de Ciencias y Artes de Barcelona, 10, 135–202. [Google Scholar] based on the presence of synchronic and sympatric adults) are described for the Neotropical Region for the first time, and the larval stages of Isostenosmylus pulverulentus (Gerstaecker, 1893 Gerstaecker, C.E.A. (1893), ‘Ueber neue und weniger gekannte Neuropteren aus der familie Megaloptera Burm’, Mitt[h]eilungen aus dem Naturwissenschaftlichen Verein für Neu-Vorpommern und Rugen, 25, 93–173. [Google Scholar]) are redescribed. The external morphology of third-instar larvae of both species and their habitats are described and compared. Kempynus sp. is a water-dependent species and can be considered semi-aquatic, whereas I. pulverulentus larvae are terrestrial and live in undergrowth vegetation. The first key to identification of Neotropical Osmylidae larvae is provided, based on third-instar larvae of both species.     

Kinetics of Choline Uptake into Isolated Rat Forebrain Microvessels: Evidence of Endocrine Modulation

The active uptake of [methyl-3H]choline into isolated rat brain microvessel suspension was studied as a likely guide to the transport of choline across the blood-brain barrier. The method consisted primarily of incubation of the suspension with a fixed concentration of labeled choline in the presence of increasing concentrations of unlabeled choline or any other inhibitor (I) of active uptake, defined as the difference in uptake at 37 degrees and 0 degrees C. From the linear regression of (1/V) against [I], the following values of Vmax (nmol g-1 min-1) and Km (microM) were obtained for choline: 2-month-old males, 10.6 +/- 3.8 and 6.1 +/- 0.9; 3-month old random females, 28.4 +/- 5.9 and 12.6 +/- 4.0; females at metaestrus, 17.8 +/- 10.3 and 8.3 +/- 5.0; at diestrus, 31.1 +/- 9.3 and 13.0 +/- 2.6; at proestrus, 54.9 +/- 2.2 and 14.0 +/- 1.5; at estrus, 19.2 +/- 2.2 and 2.6 +/- 1.7. The differences between males and random females (p less than 0.018) and between females at proestrus and estrus (p less than 0.005) are significant. It is suggested that these inter- and intrasex variations in choline uptake reflect a dynamic adjustment of supply in accordance with brain demand for choline at the time of assay. Hemicholinium-3 was an effective inhibitor of choline uptake, Ki = 14.0 +/- 8.5 microM; dimethylaminoethanol was much less effective; and imipramine had no measurable effect.     

Freshwater biota and rising pCO2?

Rising atmospheric carbon dioxide (CO₂) has caused a suite of environmental issues, however, little is known about how the partial pressure of CO₂ (pCO₂) in freshwater will be affected by climate change. Freshwater pCO₂ varies across systems and is controlled by a diverse array of factors, making it difficult to make predictions about future levels of pCO₂. Recent evidence suggests that increasing levels of atmospheric CO₂ may directly increase freshwater pCO₂ levels in lakes, but rising atmospheric CO₂ may also indirectly impact freshwater pCO₂ levels in a variety of systems by affecting other contributing factors such as soil respiration, terrestrial productivity and climate regimes. Although future freshwater pCO₂ levels remain uncertain, studies have considered the potential impacts of changes to pCO₂ levels on freshwater biota. Studies to date have focused on impacts of elevated pCO₂ on plankton and macrophytes, and have shown that phytoplankton nutritional quality is reduced, plankton community structure is altered, photosynthesis rates increase and macrophyte distribution shifts with increasing pCO₂. However, a number of key knowledge gaps remain and gaining a better understanding of how freshwater pCO₂ levels are regulated and how these levels may impact biota, will be important for predicting future responses to climate change.     

Deciphering bioactive peptides and their action mechanisms through proteomics

Introduction: Bioactive peptides such as antimicrobial peptides (AMPs), ribosomally synthesized and post translationally modified peptides (RiPPs) and the non-ribosomal peptides (NRPs) have emerged with promising applications in medicine, agriculture and industry. However, their development has been limited by several difficulties making it necessary to search for novel discovery methods. In this context, proteomics has been considered a reliable tool.

Areas covered: This review highlights recent developments in proteomic tools that facilitate the discovery of AMPs, RiPPs and NRPs as well as the elucidation of action mechanisms of AMPs and resistance mechanisms of pathogens to them.

Expert commentary: Proteomic approaches have emerged as useful tools for the study of bioactive peptides, especially mass spectrometry-based peptidomics profiling, a promising strategy for AMP discovery. Furthermore, the rapidly expanding fields of genome mining and genome sequencing techniques, as well as mass spectrometry, have revolutionized the discovery of novel RiPPs and NRPs from complex biological samples.     

Comparative phylogeography of West African amphibians and reptiles

Comparative phylogeographic studies often support shared divergence times for co-distributed species with similar life histories and habitat specializations. During the late Holocene, West Africa experienced aridification and the turnover of rain forest habitats into savannas. These fragmented rain forests harbor impressive numbers of endemic and threatened species. In this setting, populations of co-distributed rain forest species are expected to have diverged simultaneously, whereas divergence events for species adapted to savanna and forest-edge habitats should be absent or idiosyncratic. We conducted a Bayesian analysis of shared evolutionary events to test models of population divergence for 20 species of anurans (frogs) and squamates (lizards and snakes) that are distributed across the Dahomey Gap, a climate change-induced savanna barrier responsible for fragmenting previously contiguous rain forests of Ghana into two regions: the Togo-Volta Hills and the Southwestern Forests. A model of asynchronous diversification is supported for anurans and squamates, suggesting that drivers of diversification are not specifically related to ecological and life history associations with habitat types. Instead, the wide variability of genetic divergence histories exhibited by these species suggests that biodiversity in this region has been shaped by diversification events that extend beyond the Holocene. Comparisons of the genealogical divergence index, a measure of the genetic divergence between populations due to the combined effects of genetic isolation and gene flow, illustrate that these populations represent a broad sampling of the speciation continuum.     

Determination of Moulting Events in Rock Lobsters from Pleopod Clipping

Rock lobster growth is routinely measured for research to optimise management measures such as size limits and quotas. The process of estimating growth is complicated in crustaceans as growth only occurs when the animal moults. As data are typically collected by tag-recapture methods, the timing of moulting events can bias results. For example, if annual moulting events take place within a very short time-at-large after tagging, or if time-at-large is long and no moulting occurs. Classifying data into cases where moulting has / has not occurred during time-at-large can be required and can generally be determined by change in size between release and recapture. However, in old or slow growth individuals the moult increment can be too small to provide surety that moulting has occurred. A method that has been used since the 1970’s to determine moulting in rock lobsters involves clipping the distal portion of a pleopod so that any regeneration observed at recapture can be used as evidence of a moult. We examined the use of this method in both tank and long-duration field trials within a marine protected area, which provided access to large animals with smaller growth increments. Our results emphasised that determination of moulting by change in size was unreliable with larger lobsters and that pleopod clipping can assist in identifying moulting events. However, regeneration was an unreliable measure of moulting if clipping occurred less than three months before the moult.