How to be an attractive male: floral dimorphism and attractiveness to pollinators in a dioecious plant

Background  

Sexual selection theory predicts that males are limited in their reproductive success by access to mates, whereas females are more limited by resources. In animal-pollinated plants, attraction of pollinators and successful pollination is crucial for reproductive success. In dioecious plant species, males should thus be selected to increase their attractiveness to pollinators by investing more than females in floral traits that enhance pollinator visitation. We tested the prediction of higher attractiveness of male flowers in the dioecious, moth-pollinated herb Silene latifolia, by investigating floral signals (floral display and fragrance) and conducting behavioral experiments with the pollinator-moth, Hadena bicruris.     

The catabolism of plasmenylcholine in the guinea pig heart.

The hydrolysis of the alkenyl bonds of plasmenylcholine and plasmenylethanolamine by plasmalogenase, followed by hydrolysis of the resultant lysophospholipid by lysophospholipase, has been postulated as the major pathway for the catabolism of these plasmalogens. However, the postulation was based solely on the presence of plasmalogenase activity towards plasmenylethanolamine and plasmenylcholine in the brain. In this study we have demonstrated the absence of plasmalogenase activity for plasmenylcholine in the guinea pig heart under a wide range of experimental conditions. Plasmenylcholine was hydrolysed by phospolipase A2 activities in cardiac microsomal, mitochondrial and cytosolic fractions. Phospholipase A2 activities in these fractions had an alkaline pH optimum and were enhanced by Ca2+. The enzymes also displayed high specificity for plasmenylcholine with linoleoyl or oleoyl at the C-2 position. Lysoplasmalogenase activity for lysoplasmenycholine was also detected and characterized in the microsomal and mitochondrial fractions. Since the cardiac plasmalogenase is only active towards plasmenylethanolamine but not plasmenylcholine, the catabolism of these two plasmalogens must be different from each other. We postulate that the major pathway for the catabolism of plasmenycholine involves the hydrolysis of the C-2 fatty acid by phospholipase A2, and hydrolysis of the vinyl ether group of the resultant lysoplasmenylcholine by lysoplasmalogenase.     

Loss of transferrin receptors following induced differentiation of HL-60 promyelocytic leukemia cells

Human promyelocytic leukemia (HL-60) and lymphoblastoid (Daudi) cells were studied: for transferrin receptors before and after induced differentiation with dimethyl sulfoxide (DMSO), sodium butyrate or retinoic acid. None of these reagents affected the morphology or presentation of receptors in Daudi cells, but many HL-60 morphologically matured to banded neutrophils and demonstrated a concomitant loss of transferrin binding, suggesting an important role for transferrin receptors in cellular differentiation.     

Involvement of PKCζ and GSK3β in the stability of the metaphase spindle

In the somatic cell, the mitotic spindle apparatus is centrosomal, and several isoforms of protein kinase C (PKC) have been associated with the mitotic spindle, but their role in stabilizing the mitotic spindle is still unclear. Other protein kinases such as, glycogen synthase kinase 3β (GSK3β) have also been shown to be associated with the mitotic spindle apparatus. In this study, we show the enrichment of active (phosphorylated) PKCζ at the centrosomal region of the spindle apparatus in metaphase stage of 3T3 cells. In order to understand whether the two kinases PKC and GSK3β are associated with the mitotic spindle, first, the co-localization of phosphorylated PKC isoforms with GSK3β was studied at the poles in metaphase cells. Fluorescence resonance energy transfer (FRET) analysis was used to demonstrate close molecular proximity of phospho-PKCζ with phospho(ser9)GSK3β. Second, the involvement of inactive GSK3β in maintaining an intact mitotic spindle in 3T3 cells was shown. Third, this study also showed that addition of a phospho-PKCζ specific inhibitor to cells can disrupt the mitotic spindle microtubules and some of the proteins associated with it. The mitotic spindle at metaphase in mouse fibroblasts appears to be maintained by PKCζ acting through GSK3β. Phospho-PKCζ is in close molecular proximity to GSK3β, whereas the other isoforms of PKC such as pPKCβII, pPKCγ, pPKCμ, and pPKCθ are not close enough to have significant FRET readings. The close molecular proximity supports the idea that GSK3β may be a substrate of PKCζ.     

Seasonal diet changes in elephant and impala in mopane woodland

Elephant and impala as intermediate feeders, having a mixed diet of grass and browse, respond to seasonal fluctuations of forage quality by changing their diet composition. We tested the hypotheses that (1) the decrease in forage quality is accompanied by a change in diet from more monocots in the wet season to more dicots in the dry season and that that change is more pronounced and faster in impala than in elephant; (2) mopane (Colophospermum mopane), the most abundant dicot species, is the most important species in the elephant diet in mopane woodland, whereas impala feed relatively less on mopane due to the high condensed tannin concentration; and (3) impala on nutrient-rich soils have a diet consisting of more grass and change later to diet of more browse than impala on nutrient-poor soils. The phosphorus content and in vitro digestibility of monocots decreased and the NDF content increased significantly towards the end of the wet season, whereas in dicots no significant trend could be detected. We argue that this decreasing monocot quality caused elephant and impala to consume more dicots in the dry season. Elephant changed their diet gradually over a 16-week period from 70% to 25% monocots, whereas impala changed diets rapidly (2?C4?weeks) from 95% to 70% monocots. For both elephants and impala, there was a positive correlation between percentage of monocots and dicots in the diet and the in vitro digestibility of these forage items. Mopane was the most important dicot species in the elephant diet and its contribution to the diet increased significantly in the dry season, whereas impala selected other dicot species. On nutrient-rich gabbroic soils, impala ate significantly more monocots than impala from nutrient-poor granitic soils, which was related to the higher in vitro digestibility of the monocots on gabbroic soil. Digestibility of food items appears to be an important determinant of diet change from the wet to the dry season in impala and elephants.     

HIV/AIDS among Inmates of and Releasees from US Correctional Facilities, 2006: Declining Share of Epidemic but Persistent Public Health Opportunity

Because certain groups at high risk for HIV/AIDS (human immunodeficiency virus/acquired immunodeficiency syndrome) come together in correctional facilities, seroprevalence was high early in the epidemic. The share of the HIV/AIDS epidemic borne by inmates of and persons released from jails and prisons in the United States (US) in 1997 was estimated in a previous paper. While the number of inmates and releasees has risen, their HIV seroprevalence rates have fallen. We sought to determine if the share of HIV/AIDS borne by inmates and releasees in the US decreased between 1997 and 2006. We created a new model of population flow in and out of correctional facilities to estimate the number of persons released in 1997 and 2006. In 1997, approximately one in five of all HIV-infected Americans was among the 7.3 million who left a correctional facility that year. Nine years later, only one in seven (14%) of infected Americans was among the 9.1 million leaving, a 29.3% decline in the share. For black and Hispanic males, two demographic groups with heightened incarceration rates, recently released inmates comprise roughly one in five of those groups'' total HIV-infected persons, a figure similar to the proportion borne by the correctional population as a whole in 1997. Decreasing HIV seroprevalence among those admitted to jails and prisons, prolonged survival and aging of the US population with HIV/AIDS beyond the crime-prone years, and success with discharge planning programs targeting HIV-infected prisoners could explain the declining concentration of the epidemic among correctional populations. Meanwhile, the number of persons with HIV/AIDS leaving correctional facilities remains virtually identical. Jails and prisons continue to be potent targets for public health interventions. The fluid nature of incarcerated populations ensures that effective interventions will be felt not only in correctional facilities but also in communities to which releasees return.     

Upregulation of intracellular antioxidant enzymes in brain and heart during estivation in the African lungfish Protopterus dolloi

The African slender lungfish, Protopterus dolloi, is highly adapted to withstand periods of drought by secreting a mucous cocoon and estivating for periods of months to years. Estivation is similar to the diapause and hibernation of other animal species in that it is characterized by negligible activity and a profoundly depressed metabolic rate. As is typically observed in quiescent states, estivating P. dolloi are resistant to environmental stresses. We tested the hypothesis that P. dolloi enhances stress resistance during estivation by upregulating intracellular antioxidant defences in brain and heart tissues. We found that most of the major intracellular antioxidant enzymes, including the mitochondrial superoxide dismutase, cytosolic superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase, were upregulated in brain tissue of lungfish that had estivated for 60 days. Several of these enzymes were also elevated in heart tissue of estivators. These changes were not due to food deprivation, as they did not occur in a group of fish that were deprived of food but maintained in water for the same period of time. We found little evidence of tissue oxidative damage in estivators. Products of lipid peroxidation (4-hydroxynonenal adducts) and oxidative protein damage (carbonylation) were similar in estivating and control lungfish. However, protein nitrotyrosine levels were elevated in brain tissue of estivators. Taken together, these data indicate that estivating P. dolloi have enhanced oxidative stress resistance in brain and heart due to a significant upregulation of intracellular antioxidant capacity.     

Assessing morphological and DNA-based diet analysis techniques in a generalist predator, the arrow squid Nototodarus gouldi

Establishing the diets of marine generalist consumers is difficult, with most studies limited to the use of morphological methods for prey identification. Such analyses rely on the preservation of diagnostic hard parts, which can limit taxonomic resolution and introduce biases. DNA-based analyses provide a method to assess the diets of marine species, potentially overcoming many of the limitations introduced by other techniques. This study compared the effectiveness of morphological and DNA-based analysis for determining the diet of a free-ranging generalist predator, the arrow squid (Nototodarus gouldi). A combined approach was more effective than using either of the methods in isolation. Nineteen unique prey taxa were identified, of which six were found by both methods, 10 were only detected using DNA and three were only identified using morphological methods. Morphological techniques only found 50% of the total number of identifiable prey taxa, whereas DNA-based techniques found 84%. This study highlights the benefits of using a combination of techniques to detect and identify prey of generalist marine consumers.     

Mathematical modeling of an aqueous film coating process in a Bohle Lab-Coater: Part 2: Application of the model

For the prediction of the air and product temperatures, the product moisture, and the air humidity during a coating process in a Bohle Lab-Coater, a model was developed. The purpose of this work was to determine the limit moisture, the critical moisture, and the constant for the exchange rate between both zones and to use these values for other sets of experiments to test the model. The adaptation of the 3 parameters (limit moisture, critical moisture, and exchange rate constant), was done by calculation of the product temperature in both zones for several sets of parameters in order to minimize the sum of square deviation between the calculated and the measured product temperatures. This set of parameters was used to test the validity of the model. By applying the model, the product temperature could be predicted based on the product, process, and equipment-related parameters. Hence, the model can be used to theoretically investigate the influence of different process paramaters. The mean difference between the predicted, and measured product temperatures in the steady state is ≈2 up to 3 K using the determined parameter set for the limit moisture, the critical moisture, and the exchange rate constant. The model is useful for the prediction of the air and product temperatures, the product moisture, and air humidity during a coating process in the Bohle Lab-Coater using round, biconvex tablets.