Effect of pulsed exposure to heavy metals (copper and cadmium) on some population variables of <Emphasis Type="Italic">Brachionus calyciflorus</Emphasis> Pallas (Rotifera: Brachionidae: Monogononta)

Heavy metals are widely recognized as potential toxic agents to zooplankton, yet experiments are usually performed with a continuous exposure to the metal being analyzed. Here we describe experiments that examined the influence of pulsed exposure of the heavy metals copper and cadmium to a parthenogenetic population of the planktonic rotifer Brachionus calyciflorus. Our protocol called for exposure durations of 3, 6, 12, and 24 h to either copper (as CuSO₄) at concentrations of 0.0375, 0.075, 0.15 mg l⁻¹ or cadmium (as CdCl₂) at concentration of 0.025, 0.05, 0.1 mg l⁻¹. Control animals were treated in similar ways but did not receive exposure to heavy metals. Four end points were used to evaluate the outcome of exposure: population growth (r), body size, egg ratio, and egg hatching percent. Increase in heavy metal concentration and exposure time had an adverse influence on the population growth of B. calyciflorus. However, while the response of B. calyciflorus was similar for both heavy metals, the magnitude of the impact of cadmium was more severe. Population growth varied depending on which heavy metal was tested, as well as its concentration and the duration of exposure (r = 0.11–0.28 day⁻¹). There was a significant reduction in lorica size of B. calyciflorus subjected to different exposure times and concentrations of both Cd and Cu. Egg ratios were inversely related to population density in controls and in treatments involving Cu, but not for Cd. While nearly 100% of eggs hatched in the control treatments, egg hatching in experimental treatments containing Cu, were reduced (range = 16–41%) depending on the exposure time and the concentration. Guest editors: S. S. S. Sarma, R. D. Gulati, R. L. Wallace, S. Nandini, H. J. Dumont & R. Rico-Martínez Advances in Rotifer Research     

Probiotic therapy for the prevention and treatment of Clostridium difficile-associated diarrhea: a systematic review

BackgroundThe recent increase in the number and severity of cases of nosocomial Clostridium difficile-associated diarrhea (CDAD) has prompted interest in the use of probiotics for the prevention and treatment of this disease. We performed a systematic review of randomized controlled trials to assess the effectiveness of probiotic therapy.MethodsWe searched the PubMed, EMBASE, INAHTA, HEN and Cochrane Collaboration databases to identify trials in which the prevention or treatment of CDAD with probiotic therapy was the primary or secondary outcome. We extracted data on the number of patients randomly assigned to receive probiotic or placebo, the number of patients with CDAD, the type of probiotic, criteria for diagnosing CDAD, persistence of infection after treatment, compliance and adverse effects.ResultsWe identified 4 eligible studies in which prevention (n = 1) or treatment (n = 3) of CDAD was the primary outcome. The benefit of probiotic therapy seen in 2 of the studies was restricted to subgroups characterized by severe CDAD and increased use of vancomycin. The remaining 2 studies were too methodologically flawed for us to draw meaningful conclusions. We also identified 4 trials in which prevention of antibiotic-associated diarrhea with probiotics was the primary outcome and prevention of CDAD a secondary outcome. These studies were limited primarily by too few CDAD cases and provided no evidence of effective prophylaxis. Overall, heterogeneity in choice and dose of probiotic and in criteria for diagnosing CDAD makes it difficult to synthesize information from the 8 studies.InterpretationStudies conducted to date provide insufficient evidence for the routine clinical use of probiotics to prevent or treat CDAD. Better designed and larger studies are needed.Both the incidence and severity of Clostridium difficile-associated diarrhea (CDAD) have increased in hospitals across North America.^1,2,3,4 Recent outbreaks in Montreal and Sherbrooke resulted in a 4-fold increase in the number of CDAD cases as well as an increase in the number of attributable deaths.^1,5,6,7 CDAD is a debilitating and costly illness, particularly among patients with recurring episodes. Probiotics, or naturally occurring “good bacteria,” have been suggested as a means of both preventing and treating the disease.^8,9,10,11 The disturbance of normal gastrointestinal flora, particularly after antibiotic use, is believed to predispose patients to colonization by C. difficile;² probiotics, by delivering bacteria to the gastrointestinal tract, are believed to restore equilibrium in the altered gastrointestinal flora and thus protect against colonization.⁸ Probiotics that have been proposed for prevention and treatment of antibiotic-associated diarrhea and CDAD include various bacteria (Bifidobacterium, Lactobacillus GG, L. rhamnosus, L. casei, L. plantarum 299v, Enteroccus faecium [SF68]) and yeasts (Saccharomyces boulardii, S. cerevisiae). They are commonly available as lyophilized capsules or in the form of a fermented drink. We performed a systematic review of randomized controlled trials of probiotic therapy for the prevention and treatment of CDAD.     

Advances in immunoproteomics for serological characterization of microbial antigens

We propose a multi-dimensional strategy, associating immunodetection to a protein fractionating two-dimensional liquid chromatography tool, for serological characterization of microbial antigens. The originality of such immunoproteomic approaches resides in their application in large-scale studies for rapid serotyping of micro-organisms, evaluation of immunomes and could be proposed in the development and monitoring of vaccines.     

Growth stimulation by serum in Entamoeba histolytica is associated with protein tyrosine dephosphorylation

Very little protein tyrosine phosphorylation was observed in growing (exponential-phase) Entamoeba histolytica cells by immunoblotting and quantitative immunofluorescence. After 1 h of serum deprivation, two proteins (42 and 38 kDa in SDS-PAGE) were tyrosine phosphorylated and two more proteins (96 and 63 kDa) also showed tyrosine phosphorylation when examined after 4 h of serum deprivation. Intense enhancements of anti-phosphotyrosine immunofluorescence levels were observed during this period of serum withdrawal. Membrane-associated tyrosine kinase activity reached a peak (3.5-fold increase) 1 h after serum deprivation and decreased thereafter reaching a basal level by 2 h of serum deprivation. Interestingly, tyrosine kinase activities remained unaffected by serum stimulation (2-60 min) of serum-deprived cells. Also, during this period of serum stimulation tyrosine phosphorylated proteins of serum-deprived cells were dephosphorylated. Tyrosine phosphatase activities were suppressed during serum deprivation and on serum addition to serum-deprived cells tyrosine phosphatase activities increased significantly. Our data attest that protein tyrosine phosphorylation was associated with growth inhibition of E. histolytica and serum stimulation of E. histolytica produced tyrosine phosphatase activation and protein tyrosine dephosphorylation.     

Talaromyces marneffei Outside Endemic Areas in India: an Emerging Infection with Atypical Clinical Presentations and Review of Published Reports from India

Mycopathologia - Talaromycosis is a disseminated disease caused by Talaromyces (Penicillium) marneffei, mainly seen in acquired immunodeficiency syndrome (AIDS) patients. Its distribution is...     

Degrons at the C terminus of the pathogenic but not the nonpathogenic hantavirus G1 tail direct proteasomal degradation

Pathogenic hantaviruses cause two human diseases: hantavirus pulmonary syndrome (HPS) and hemorrhagic fever with renal syndrome (HFRS). The hantavirus G1 protein contains a long, 142-amino-acid cytoplasmic tail, which in NY-1 virus (NY-1V) is ubiquitinated and proteasomally degraded (E. Geimonen, I. Fernandez, I. N. Gavrilovskaya, and E. R. Mackow, J. Virol. 77: 10760-10768, 2003). Here we report that the G1 cytoplasmic tails of pathogenic Andes (HPS) and Hantaan (HFRS) viruses are also degraded by the proteasome and that, in contrast, the G1 tail of nonpathogenic Prospect Hill virus (PHV) is stable and not proteasomally degraded. We determined that the signals which direct NY-1V G1 tail degradation are present in a hydrophobic region within the C-terminal 30 residues of the protein. In contrast to that of PHV, the NY-1V hydrophobic domain directs the proteasomal degradation of green fluorescent protein and constitutes an autonomous degradation signal, or "degron," within the NY-1V G1 tail. Replacing 4 noncontiguous residues of the NY-1V G1 tail with residues present in the stable PHV G1 tail resulted in a NY-1V G1 tail that was not degraded by the proteasome. In contrast, changing a different but overlapping set of 4 PHV residues to corresponding NY-1V residues directed proteasomal degradation of the PHV G1 tail. The G1 tails of pathogenic, but not nonpathogenic, hantaviruses contain intervening hydrophilic residues within the C-terminal hydrophobic domain, and amino acid substitutions that alter the stability or degradation of NY-1V or PHV G1 tails result from removing or adding intervening hydrophilic residues. Our results identify residues that selectively direct the proteasomal degradation of pathogenic hantavirus G1 tails. Although a role for the proteasomal degradation of the G1 tail in HPS or HFRS is unclear, these findings link G1 tail degradation to viral pathogenesis and suggest that degrons within hantavirus G1 tails are potential virulence determinants.     

Morphological evolution through integration: a quantitative study of cranial integration in Homo, Pan, Gorilla and Pongo

Morphological integration refers to coordinated variation among traits that are closely related in development and/or function. Patterns of integration can offer important insight into the structural relationship between phenotypic units, providing a framework to address questions about phenotypic evolvability and constraints. Integrative features of the primate cranium have recently become a popular subject of study. However, an important question that still remains under-investigated is: what is the pattern of cranial shape integration among closely related hominoids? To address this question, we conducted a Procrustes-based geometric morphometrics study to quantify and analyze shape covariation patterns between different cranial regions in Homo, Pan, Gorilla and Pongo. A total of fifty-six 3D landmarks were collected on 407 adult individuals. We then sub-divided the landmarks corresponding to cranial units as outlined in the ‘functional matrix hypothesis.’ Sub-dividing the cranium in this manner allowed us to explore patterns of covariation between the face, basicranium and cranial vault, using the two-block partial least squares approach. Our results suggest that integrated shape changes in the hominoid cranium are complex, but that the overall pattern of integration is similar among human and non-human apes. Thus, despite having very distinct morphologies the way in which the face, basicranium and cranial vault covary is shared among these taxa. These results imply that the pattern of cranial integration among hominoids is conserved.