Mucosal lymphatic-derived gammadelta T cells respond early to experimental Salmonella enterocolitis by increasing expression of IL-2R alpha

To better understand the roles of gammadelta T cells in mucosal infection, we utilized Salmonella enterica serovar Typhimurium (Salmonella serovar Typhimurium) infection in cattle as it closely approximates Salmonella serovar Typhimurium-induced enterocolitis in humans. Protein and gene expression in alphabeta and gammadelta T cells derived from lymphatic ducts draining the gut mucosa in Salmonella serovar Typhimurium-infected calves were analyzed. In calves with enterocolitis, general gene expression trends in gammadelta T cells suggested subtle activation and innate response, whereas alphabeta T cells were relatively quiescent following Salmonella serovar Typhimurium infection. An increase in IL-2R alpha expression on gammadelta T cells from infected calves and results from in vitro assays suggested that gammadelta T cells were primed by Salmonella serovar Typhimurium LPS to better respond to IL-2 and IL-15. Together with gene expression trends in vivo, these data support early priming activation of target tissue gammadelta T cells during Salmonella serovar Typhimurium infection.     

Cytoskeleton and cell wall function in penetration resistance

Plants successfully repel the vast majority of potential pathogens that arrive on their surface, with most microorganisms failing to breach the outer epidermal wall. Resistance to penetration at the epidermis is a key component of basal defence against disease and critically depends on fortification of the cell wall at the site of attempted penetration through the development of specialised cell wall appositions rich in antimicrobial compounds. Formation of cell wall appositions is achieved by rapid reorganisation of actin microfilaments, actin-dependent transport of secretory products to the infection site and local activation of callose synthesis. Plants are finely tuned to detect the presence of pathogens on their surface, perceiving both chemical and physical signals of pathogen origin. In the on-going evolution of interaction strategies, plants must continually monitor and out manoeuvre pathogen avoidance or suppression of plant defences in order to preserve the effectiveness of penetration resistance.     

Expression and function of cyclooxygenase and lipoxygenase enzymes in human islets of Langerhans

Arachidonic acid (AA) is generated in pancreatic beta-cells through the activation of Ca2+-dependent cytosolic phospholipase A2 (cPLA2) and the consequent hydrolysis of membrane phospholipids in the sn-2 position of the glycerophospholipid backbone. AA acts as a second messenger in beta-cells to elevate cytosolic Ca2+ levels and stimulate insulin secretion, but it is not clear whether these are direct effects of AA or are dependent on its metabolism by cyclooxygenase (COX) and/or lipoxygenase (LOX) enzymes. In addition, much of the published data in this area have been generated using insulin-secreting cell lines or rodent islets, with very little information on AA generation and metabolism in human islets of Langerhans. This short review examines cPLA2, COX and LOX expression and function in insulin- secreting cell lines and rodent and human islets.     

Comparison of delayed female mating on reproductive biology of codling moth and obliquebanded leafroller

Delay of mating was examined as a possible mechanism for population decreases associated with mating disruption for codling moth, Cydia pomonella L., and obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae). We examined the effect of delaying female mating 0, 2, 4, or 6 d while holding male age constant on life table parameters of both species. We found that increasing delays in mating were accompanied by two responses: (1) an increase in the percentage of sterile pairs and (2) a reduction in net reproductive rate and population growth unrelated to sterility. On a percentage basis, obliquebanded leafroller population growth was more strongly affected than codling moth. However, the net fertility rate of obliquebanded leafroller was nearly eight-fold higher than that of codling moth, so that obliquebanded leafroller females that experienced a 4-d delay in mating had nearly the same reproductive rate as codling moth females that experienced no delay. Leslie matrix simulations using life tables with field-based adult longevity estimates showed that codling moth females experiencing >2-d delay in mating resulted in decreases in population density or extinction within two generations. In contrast, obliquebanded leafroller females delayed <6 d showed rapid population growth that decreased as female age at mating increased; only the 6-d delay treatment resulted in decreased population levels. Our results indicate that obliquebanded leafroller females must on average experience a much longer delay in mating to significantly reduce population growth compared with codling moth females, suggesting that delay of mating likely plays a greater role in codling moth mating disruption than for obliquebanded leafroller.     

Cellular internalization and distribution of arginine-rich peptides as a function of extracellular peptide concentration, serum, and plasma membrane associated proteoglycans

The exact mechanisms by which arginine-rich cell-penetrating peptides enter cells are still the subject of debate. Here, we have analyzed in detail the effects of serum and extracellular concentration on the internalization of oligoarginines (R n; n = 4, 8, 12, 16). The presence of serum in the incubation medium had a major influence on the uptake of R12 and R16 peptides but did not affect the uptake of R4 and R8 significantly. Incubation of cells at 37 degrees C with R12 and R16 peptides in serum-containing medium showed that the majority of labeling was confined to punctate endocytic structures. Performing the same experiments in serum-free media led to a dramatic increase in cytosolic labeling, and similarly diffuse R12 and R16 labeling was observed in cells treated with peptides at 4 degrees C. This suggests, in both cases, that the peptides were entering via a nonendocytic mechanism. Further studies on R12 peptide suggest that the initiation of nonendocytic uptake and cytosolic labeling is also dependent on serum concentration and extracellular peptide concentration. At relatively low concentrations, the peptide labels endocytic structures, but upon raising the peptide concentration, the fraction labeling the cytosol increases dramatically and this accompanies a nonlinear increase in total cellular fluorescence. Membrane-associated proteoglycans also contribute to increasing the peptide concentration at the cell surface by enhancing their recruitment via electrostatic interactions. These results demonstrate that uptake mechanisms of these compounds are highly dependent on both the presence of serum and the effective extracellular peptide concentration.     

A comparative metabolomic study of NHR-49 in Caenorhabditis elegans and PPAR-alpha in the mouse

Proton Nuclear Magnetic Resonance spectroscopy and Gas Chromatography Mass Spectrometry based metabolomics has been used in conjunction with multivariate statistics to examine the metabolic changes in Caenorhabditis elegans following the deletion of nuclear hormone receptor-49 (nhr-49). Deletion of the receptor produced profound changes in fatty acid metabolism, in particular an increase in the ratio of unsaturated to saturated fatty acids, a decrease in the concentration of glucose and increases in lactate and alanine. Given the proposed functional similarity between nhr-49 and the mammalian peroxisome proliferator-activated receptors (PPARs) these changes were compared with the metabolome of the PPAR-alpha null mouse. The metabolomic approach demonstrated a number of similarities including the regulation of lipid synthesis, beta-oxidation of fatty acids and changes in glycolysis/gluconeogenesis.     

A cytochrome b561 with ferric reductase activity from the parasitic blood fluke, Schistosoma japonicum

Background

Iron has an integral role in numerous cellular reactions and is required by virtually all organisms. In physiological conditions, iron is abundant in a largely insoluble ferric state. Ferric reductases are an essential component of iron uptake by cells, reducing iron to the soluble ferrous form. Cytochromes b561 (cyts-b561) are a family of ascorbate reducing transmembrane proteins found in most eukaryotic cells. The identification of the ferric reductase duodenal cytochrome b (dcytb) and recent observations that other cyts-b561 may be involved in iron metabolism have opened novel perspectives for elucidating their physiological function.

Methodology/Principal Findings

Here we have identified a new member of the cytochrome b561 (Sjcytb561) family in the pathogenic blood fluke Schistosoma japonicum that localises to the outer surface of this parasitic trematode. Heterologous expression of recombinant Sjcyt-b561 in a Saccharomyces cerevisiae mutant strain that lacks plasma membrane ferrireductase activity demonstrated that the molecule could rescue ferric reductase activity in the yeast.

Significance/Conclusions

This finding of a new member of the cytochrome b561 family further supports the notion that a ferric reductase function is likely for other members of this protein family. Additionally, the localisation of Sjcytb561 in the surface epithelium of these blood-dwelling schistosomes contributes further to our knowledge concerning nutrient acquisition in these parasites and may provide novel targets for therapeutic intervention.     

Synanthropic primates in Asia: Potential sentinels for environmental toxins

Macaques are similar to humans both physiologically and behaviorally. In South and Southeast Asia they are also synanthropic, ecologically associated with humans. Synanthropy with humans raises the possibility that macaques come into contact with anthropogenic toxicants, such as lead and mercury, and might be appropriate sentinels for human exposures to certain toxic materials. We measured lead (Pb) and mercury (Hg) levels and characterized the stable isotopic compositions of δ¹⁵N and δ¹³C in hair from three groups of free‐ranging macaques at the Swoyambhu temple in Kathmandhu, Nepal, an urban population that has abundant contact with humans. Hair lead levels were significantly higher among young macaques and differed among the three groups of macaques that were sampled. Hair Hg levels were low. No statistical association was found between stable isotopic compositions (δ¹⁵N and δ¹³C) and Pb and Hg levels. Our data did not find evidence that lead levels were associated with diet. We conclude that, in this population of macaques, behavioral and/or physiologic factors may play a significant role in determining exposure to lead. Chemical analysis of hair is a promising, noninvasive technique for determining exposure to toxic elements in free‐ranging nonhuman primates. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc.     

Whole-genome scan, in a complex disease, using 11,245 single-nucleotide polymorphisms: comparison with microsatellites

Despite the theoretical evidence of the utility of single-nucleotide polymorphisms (SNPs) for linkage analysis, no whole-genome scans of a complex disease have yet been published to directly compare SNPs with microsatellites. Here, we describe a whole-genome screen of 157 families with multiple cases of rheumatoid arthritis (RA), performed using 11,245 genomewide SNPs. The results were compared with those from a 10-cM microsatellite scan in the same cohort. The SNP analysis detected HLA*DRB1, the major RA susceptibility locus (P=.00004), with a linkage interval of 31 cM, compared with a 50-cM linkage interval detected by the microsatellite scan. In addition, four loci were detected at a nominal significance level (P<.05) in the SNP linkage analysis; these were not observed in the microsatellite scan. We demonstrate that variation in information content was the main factor contributing to observed differences in the two scans, with the SNPs providing significantly higher information content than the microsatellites. Reducing the number of SNPs in the marker set to 3,300 (1-cM spacing) caused several loci to drop below nominal significance levels, suggesting that decreases in information content can have significant effects on linkage results. In contrast, differences in maps employed in the analysis, the low detectable rate of genotyping error, and the presence of moderate linkage disequilibrium between markers did not significantly affect the results. We have demonstrated the utility of a dense SNP map for performing linkage analysis in a late-age-at-onset disease, where DNA from parents is not always available. The high SNP density allows loci to be defined more precisely and provides a partial scaffold for association studies, substantially reducing the resource requirement for gene-mapping studies.     

Symmetric faces are a sign of successful cognitive aging

It has been proposed that a common cause underlies individual differences in bodily and cognitive decline in old age. No good marker for this common cause has been identified to date. Here, fluctuating asymmetry (FA), an indicator of developmental stability that relates to intelligence differences in young adults, was measured from facial photographs of 216 surviving members of the Lothian Birth Cohort 1921 at age 83 and related to their intelligence at ages 11, 79 and 83 years. FA at age 83 was unrelated to intelligence at ages 11 and 79 and to cognitive change between 11 and 79 years. It was, however, associated with intelligence and information processing efficiency at age 83 and with cognitive change between 79 and 83 years. Significant results were limited to men, a result predicted by sex differences in life history tradeoffs and life expectancy. Results were stronger when directional asymmetries were corrected in facial FA measures. Thus, FA is a candidate marker for the common cause of differential senescence.