SUPPORT FOR THE IMMUNOCOMPETENCE HANDICAP HYPOTHESIS IN THE WILD: HORMONAL MANIPULATION DECREASES SURVIVAL IN SICK DAMSELFLIES

The immunocompetence handicap hypothesis (ICHH) states that hormones enhance sexual trait expression but impair immunity. Previous tests of the ICHH have been hampered by experimental design problems. Here, we report on an experimental test of the ICHH that includes manipulations of both hormones and infections in males of the territorial damselfly, Hetaerina americana, with accurate survival measurements. We conducted a fully factorial experiment subjecting each individual to one of three topical treatments: methoprene (a juvenile hormone analog), acetone, or control, and one of three injection treatments: bacteria, PBS, or control. We measured survival of manipulated males in both the wild and in captivity. As predicted, survival was most heavily impaired in methoprene‐bacteria males than in the other groups in the wild, and no survival differences emerged in captive animals. This result confirms that survival is one cost an animal pays for increased hormonal levels. This corroborates theoretical predictions of the ICHH.     

Improvements in obtaining New World Leishmania sp from mucosal lesions: Notes on isolating and stocking parasites

Tegumentary leishmaniasis is an endemic protozoan disease that, in Brazil, is caused by parasites from Viannia or Leishmania complex. The clinical forms of cutaneous disease comprise localized, disseminated, mucosal or mucocutaneous, and diffuse leishmaniasis. Viannia complex parasites are not easy to isolate from patient lesions, especially from mucosal lesions, and they are difficult to culture. The aim of the present study was to compare the efficiency of ex vivo (culture) and in vivo (IFNγ-deficient mice) parasite isolation methods to improve the isolation rate and storage of stocks of New World Leishmania sp that cause cutaneous leishmaniasis (CL) or mucosal leishmaniasis (ML). Biopsy fragments from cutaneous or mucosal lesions were inoculated into culture medium or mouse footpads. We evaluated 114 samples (86 CL, 28 ML) using both methods independently. Samples from CL patients had a higher isolation rate in ex vivo cultures than in mice (34.1% vs. 18.7%, P<0.05). Nevertheless, almost twice the number of isolates from ML lesions was isolated using the mouse model compared to ex vivo cultures (mouse, 6/25; culture, 3/27). The overall rates of isolation were 40.2% for CL samples and 29.6% for ML samples. Of the 43 isolations, we successfully stocked 35 isolates (81.4%; 27 CL, 8 ML). Contaminations were more frequently detected in cultures of ML than CL lesions. For comparison, the use of both methods simultaneously was performed in 74 samples of CL and 25 samples of ML, and similar results were obtained. Of the eight ML isolates, five were isolated only in mice, indicating the advantage of using the in vivo method to obtain ML parasites. All parasites obtained from in vivo isolation were cryopreserved, whereas only 68% of ex vivo isolations from CL lesions were stocked. In conclusion, the use of genetically modified mice can improve the isolation of parasites from ML. Isolation and stocking of New World Leishmania parasites, especially those from ML that are almost absent in laboratory stocks, are critical for evaluating parasite genetic diversity as well as studying host-parasite interactions to identify biological markers of Leishmania. In this paper, we also discuss some of the difficulties associated with isolating and stocking parasites.     

An invaded invader: high prevalence of entocytherid ostracods on the red swamp crayfish <Emphasis Type="Italic">Procambarus clarkii</Emphasis> (Girard, 1852) in the Eastern Iberian Peninsula

The American red swamp crayfish Procambarus clarkii (Girard, 1852) was introduced in 1973 into the Iberian Peninsula for commercial purposes. As a result of both the expansion from the Iberian Peninsula and, probably, further introductions in other European countries, now it is widely distributed throughout much of Europe. The ecological impacts of this invading crayfish have received increasing attention, but nothing is known about its symbiotic entocytherid ostracods outside the American continent. The present survey has examined more than 200 crayfishes from 12 localities distributed over a wide area of Eastern Spain. Entocytherid ostracods were extracted from individual crayfishes and they were identified, counted, assigned to developmental instars and sexed. In all the study locations but one, we found at least one crayfish individual infected by entocytherid ostracods and the species determined was the same in all cases: Ankylocythere sinuosa (Rioja, 1942). The number of ostracods on individual P. clarkii varied notably in relation to crayfish size and also differed significantly among sampling sites. The crayfish size effects on ostracod densities might be related to the amount of resources and to the crayfish age and moulting frequency affecting ostracod distribution and population structure. In addition, the spatial variation in ostracod densities could also be related to site-specific habitat traits and the variability of crayfish population dynamics. Our study represents the first citation of an alien entocytherid species in Europe and demonstrates its wide distribution in the Iberian Peninsula. Further research is needed to know the potential effects of this ostracod species on the ecology of P. clarkii and of native species, with implications on the management of this aquatic invader.     

Sensitivity of dissolved organic carbon exchange and sediment bacteria to water quality in mangrove forests

Poor water quality affects the biogeochemistry functions and the biological community structure of coastal ecosystems. In this study we investigated the effect of water quality on: (a) The exchange of dissolved organic carbon (DOC) between floodwater and mangrove forests, (b) the abundance of sediment bacteria, (c) the microbial community composition, and (d) the microbial catabolic activity. We selected six mangrove forests that were flooded by creeks with differing water qualities to test for thresholds of nutrient concentrations associated with changes in DOC dynamics and the microbial community. Our results show that in sites flooded by water high in soluble reactive phosphorus (SRP) (>20 μg l⁻¹) and NH₄ ⁺ (>30 μg l⁻¹) the DOC concentrations in the floodwater were higher than in ebb water, suggesting DOC import by the mangroves. In contrast, in sites flooded by water low in SRP (<20 μg l⁻¹) and NH₄ ⁺ (<30 μg l⁻¹), DOC concentrations in the floodwater were lower than in the ebb water, suggesting DOC export by the mangroves. Bacterial abundance was higher in sediments with low bulk density, high organic carbon and when flooded by water with low N:P (1–2), but the microbial composition and total catabolic activity assessed using Biolog Ecoplates™ did not differ among sites. The relationship between water quality, microbial communities and DOC exchange suggests that, at least during some periods of the year, poor water quality increases bacterial abundance and modifies DOC exchange of mangrove forests with floodwater and thus, their role in supporting near-shore productivity.     

Extracellular identification of a processed type II ComR/ComS pheromone of Streptococcus mutans

The competence-stimulating peptide (CSP) and the sigX-inducing peptide (XIP) are known to induce Streptococcus mutans competence for genetic transformation. For both pheromones, direct identification of the native peptides has not been accomplished. The fact that extracellular XIP activity was recently observed in a chemically defined medium devoid of peptides, as mentioned in an accompanying paper (K. Desai, L. Mashburn-Warren, M. J. Federle, and D. A. Morrison, J. Bacteriol. 194:3774-3780, 2012), provided ideal conditions for native XIP identification. To search for the XIP identity, culture supernatants were filtered to select for peptides of less than 3 kDa, followed by C(18) extraction. One peptide, not detected in the supernatant of a comS deletion mutant, was identified by tandem mass spectrometry (MS/MS) fragmentation as identical to the ComS C-terminal sequence GLDWWSL. ComS processing did not require Eep, a peptidase involved in processing or import of bacterial small hydrophobic peptides, since eep deletion had no inhibitory effect on XIP production or on synthetic XIP response. We investigated whether extracellular CSP was also produced. A reporter assay for CSP activity detection, as well as MS analysis of supernatants, revealed that CSP was not present at detectable levels. In addition, a mutant with deletion of the CSP-encoding gene comC produced endogenous XIP levels similar to those of a nondeletion mutant. The results indicate that XIP pheromone production is a natural phenomenon that may occur in the absence of natural CSP pheromone activity and that the heptapeptide GLDWWSL is an extracellular processed form of ComS, possibly the active XIP pheromone. This is the first report of direct identification of a ComR/ComS pheromone.     

Expression of NADPH oxidase in human pancreatic islets

AIMS: NADPH oxidase (NOX) is a known source of superoxide anions in phagocytic and non-phagocytic cells. In this study, the presence of this enzyme in human pancreatic islets and the importance of NADPH oxidase in human β-cell function were investigated. MAIN METHODS AND KEY FINDINGS: In isolated human pancreatic islets, the expression of NADPH oxidase components was evidenced by real-time PCR (p22(PHOX), p47(PHOX) and p67(PHOX)), Western blotting (p47(PHOX) and p67(PHOX)) and immunohistochemistry (p47(PHOX), p67(PHOX) and gp91(PHOX)). Immunohistochemistry experiments showed co-localization of p47(PHOX), p67(PHOX) and gp91(PHOX) (isoform 2 of NADPH oxidase-NOX2) with insulin secreting cells. Inhibition of NADPH oxidase activity impaired glucose metabolism and glucose-stimulated insulin secretion. SIGNIFICANCE: These findings demonstrate the presence of the main intrinsic components of NADPH oxidase comprising the NOX2 isoform in human pancreatic islets, whose activity also contributes to human β-cell function.     

Leukemia inhibitory factor stimulates the transition of primordial to primary follicle and supports the goat primordial follicle viability in vitro

The aim of this study was to evaluate the effect of leukemia inhibitory factor (LIF) on the activation and survival of preantral follicles cultured in vitro enclosed in ovarian fragments (in situ). Goat ovarian cortex was divided into fragments to be used in this study. One fragment was immediately fixed (fresh control - FC) and the remaining fragments were cultured in supplemented minimum essential medium (MEM) without (cultured control - CC) or with different concentrations of LIF (1, 10, 50, 100 or 200 ng/ml) for 1 or 7 days, at 39°C in air with 5% CO2. Fresh control, CC and treated ovarian fragments were processed for histological and fluorescence analysis. The percentage of histological normal preantral follicles cultured for 7 days with 1 ng/ml (49.3%), 10 ng/ml (58.6%) and 50 ng/ml (58%) of LIF was higher than in the CC (32.6%; p < 0.05). After 7 days of culture, the percentage of primordial follicles in situ cultured with LIF decreased and primary follicles increased in all LIF concentrations compared with FC and CC (p < 0.05). In conclusion, LIF induced primordial follicle activation and supported preantral follicle viability of goat ovarian tissues cultured for 7 days.