Characterization of functional bacterial groups in a hypersaline microbial mat community (Salins-de-Giraud, Camargue, France)

A photosynthetic microbial mat was investigated in a large pond of a Mediterranean saltern (Salins-de-Giraud, Camargue, France) having water salinity from 70 per thousand to 150 per thousand (w/v). Analysis of characteristic biomarkers (e.g., major microbial fatty acids, hydrocarbons, alcohols and alkenones) revealed that cyanobacteria were the major component of the pond, in addition to diatoms and other algae. Functional bacterial groups involved in the sulfur cycle could be correlated to these biomarkers, i.e. sulfate-reducing, sulfur-oxidizing and anoxygenic phototrophic bacteria. In the first 0.5 mm of the mat, a high rate of photosynthesis showed the activity of oxygenic phototrophs in the surface layer. Ten different cyanobacterial populations were detected with confocal laser scanning microscopy: six filamentous species, with Microcoleus chthonoplastes and Halomicronema excentricum as dominant (73% of total counts); and four unicellular types affiliated to Microcystis, Chroococcus, Gloeocapsa, and Synechocystis (27% of total counts). Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments confirmed the presence of Microcoleus, Oscillatoria, and Leptolyngbya strains (Halomicronema was not detected here) and revealed additional presence of Phormidium, Pleurocapsa and Calotrix types. Spectral scalar irradiance measurements did not reveal a particular zonation of cyanobacteria, purple or green bacteria in the first millimeter of the mat. Terminal-restriction fragment length polymorphism analysis of PCR-amplified 16S rRNA gene fragments of bacteria depicted the community composition and a fine-scale depth-distribution of at least five different populations of anoxygenic phototrophs and at least three types of sulfate-reducing bacteria along the microgradients of oxygen and light inside the microbial mat.     

Reduction of bacterial indicators and bacteriophages infecting faecal bacteria in primary and secondary wastewater treatments

AIMS: To compare the suitability of various bacterial and viral indicators to assess the removal of faecal micro-organisms by primary and secondary wastewater treatment processes. METHODS AND RESULTS: The numbers of several bacterial indicators [faecal coliforms (FC), enterococci (ENT) and sulphite-reducing clostridia (SRC)] and bacteriophages (somatic coliphages, F-specific RNA phages and bacteriophages infecting Bacteroides fragilis strain RYC2056) were determined in incoming raw sewage and effluents from various primary and secondary wastewater treatment processes in several geographical areas. Reductions in the numbers of indicators were calculated as log10 reductions. Processes based on removal and mild disinfection, showed no significant differences in the elimination of any of the indicators tested or between geographical areas. In contrast, treatment processes that include strong microbial inactivation, such as lime-aided flocculation and lagooning, showed significant differences between the log10 reductions of the various micro-organisms studied, FC showing the highest reduction and spores of SRC and phages infecting B. fragilis the lowest. CONCLUSIONS: The microbial elimination performance of treatment processes based principally on removal and mild disinfection can be evaluated with a single indicator. In contrast, processes with additional disinfecting capabilities require more than one indicator for accurate evaluation of the treatment; bacteriophages are good candidates for use as second indicators. SIGNIFICANCE AND IMPACT OF THE STUDY: Bacteriophages provide additional information for the evaluation of microbial elimination in some treatment plants. The easy, fast and cheap methods available for phage determination are feasible both in industrialized and developing countries.     

Phylogeographical history of the sponge Crambe crambe (Porifera, Poecilosclerida): range expansion and recent invasion of the Macaronesian islands from the Mediterranean Sea

We studied sequence variation in the nuclear ribosomal internal transcribed spacers (ITS-1 and ITS-2) in 111 individuals from 11 populations/localities of the sponge Crambe crambe across the core species range in the western Mediterranean Sea and Atlantic Ocean. We report the first confirmed instance of intragenomic variation in sponges. Phylogeographical, nested clade and population genetic analyses were used to elucidate the species' evolutionary history. The study revealed highly structured populations affected by restricted gene flow and isolation-by-distance. A contiguous range expansion in the whole distribution area of the sponge was inferred. Phylogenetic analyses indicate a recent origin of most sequence types that could be explained by a recent origin of the species or a by recent bottleneck event in the studied area. A recent expansion of the distribution range to the Macaronesian region from the Mediterranean Sea was also detected, suggesting that C. crambe was recently introduced from the Mediterranean Sea to the Atlantic Ocean via human-mediated transport, and that the pattern observed is not the result of a natural biogeographical relationship between these zones.     

Effect of regular training on plasma thiols,malondialdehyde and carnitine concentrations in young soccer players

Physical activity is known to induce oxidative stress in individuals subjected to intense exercise. Contrarily, there are enzymatic and nonenzymatic defence systems against oxygen radicals in aerobic organisms. Sulphydryl groups such as thiol and glutathione (GSH) can be given as an example to non-enzymatic low molecular weight antioxidants. Carnitine may be related to the performance enhancement in high intensity intermittent exercises and might probably improve the aerobic capacity by stimulating lipid oxidation in muscle cells during long term exercise. But, the effects caused by this supplement during physical activity have not been fully described in the literature. The aim of the study was to compare plasma thiols (PSH), malondialdehyde (MDA) and carnitine levels and maximal oxygen uptake (VO2(max)) of the soccers under regular training with the values of the healthy controls. Our results demonstrates that soccers seem to be under less oxidative stress, as their MDA levels were significantly lower (P < 0.001) when compared with the control group while their PSH levels were significantly elevated (P < 0.001), during resting condition. In addition, the plasma carnitine concentrations of the soccer group yields lower values while the VO2(max) yields a higher value when compared with the control group. The differences between the soccer and the control groups are significant (for both, P < 0.001). The present research reveals the fact that regular soccer training shows beneficial effect on decreasing of lipid peroxidation levels. Furthermore; the sportsmen who are under intense training programs have low plasma carnitine values which do not cause negative effect on their sportive performance.     

Selenium and zinc levels in volatile substance abusers

Plasma and erythrocyte levels of selenium (Se) and zinc (Zn) have not been investigated in volatile (inhalant) substance abusers previously, although changes in the activities of antioxidant enzymes resulting from oxidative damage caused by various constituents of volatile substances have been shown in a few animal and human studies. Concentrations of these two elements in erythrocytes and plasma of 37 adolescents with inhalant abuse were measured by atomic absorption spectrophotometry and compared with those of 37 age-matched healthy controls. Erythrocyte and plasma levels of Se and plasma level of Zn were significantly lower in the study group when compared to the control group. Chronic inhalation of volatile substances can decrease the plasma levels of Se and Zn and, thus, may lead to a decrease in the activity of antioxidant enzyme systems in adolescent abusers. The role of Se and Zn supplementation in children with inhalant abuse remains to be determined considering the reduced antioxidant activity resulting from deficiency of these trace elements.     

Association of headaches and the metals

Lack of specific markers constitutes a problem during diagnosis of headache syndromes. Recently, some metals have gained importance as biological parameters for the diagnosis and during treatment. Low-ionized Mg and high-ionized Ca/Mg in patients with daily migrainous headaches were noted. The blood Na level was shown to increase before and during headache. Headache is also a symptom of the common cold for which zinc may be an effective therapy. The existing relationship between genetic markers of the cluster headache and the efficacy of lithium salts therapy was noted. Headache was also found to be associated with toxic metals. When the health effects of mercury were investigated, the most frequently observed symptom was cephalalgia. Continuous exposure to lead was concomitant with the appearance of symptoms such as headache. In relation to some metabolic links, metals may be introduced as possible biological markers for the diagnosis and during the therapy of different headache syndromes in future clinical trials and laboratory measurements.     

Analysis of sequence upstream of the endogenous H19 gene reveals elements both essential and dispensable for imprinting

Imprinting of the linked and oppositely expressed mouse H19 and Igf2 genes requires a 2-kb differentially methylated domain (DMD) that is located 2 kb upstream of H19. This element is postulated to function as a methylation-sensitive insulator. Here we test whether an additional sequence 5' of H19 is required for H19 and Igf2 imprinting. Because repetitive elements have been suggested to be important for genomic imprinting, the requirement of a G-rich repetitive element that is located immediately 3' to the DMD was first tested in two targeted deletions: a 2.9-kb deletion (Delta D MD Delta G) that removes the DMD and G-rich repeat and a 1.3-kb deletion (Delta G) removing only the latter. There are also four 21-bp GC-rich repetitive elements within the DMD that bind the insulator-associated CTCF (CCCTC-binding factor) protein and are implicated in mediating methylation-sensitive insulator activity. As three of the four repeats of the 2-kb DMD were deleted in the initial 1.6-kb Delta DMD allele, we analyzed a 3.8-kb targeted allele (Delta 3.8kb-5'H19), which deletes the entire DMD, to test the function of the fourth repeat. Comparative analysis of the 5' deletion alleles reveals that (i) the G-rich repeat element is dispensable for imprinting, (ii) the Delta DMD and Delta DMD Delta G alleles exhibit slightly more methylation upon paternal transmission, (iii) removal of the 5' CTCF site does not further perturb H19 and Igf2 imprinting, suggesting that one CTCF-binding site is insufficient to generate insulator activity in vivo, (iv) the DMD sequence is required for full activation of H19 and Igf2, and (v) deletion of the DMD disrupts H19 and Igf2 expression in a tissue-specific manner.     

Chitin synthesis in a gas1 mutant of Saccharomyces cerevisiae

The existence of a compensatory mechanism in response to cell wall damage has been proposed in yeast cells. The increase of chitin accumulation is part of this response. In order to study the mechanism of the stress-related chitin synthesis, we tested chitin synthase I (CSI), CSII, and CSIII in vitro activities in the cell-wall-defective mutant gas1 delta. CSI activity increased twofold with respect to the control, a finding in agreement with an increase in the expression of the CHS1 gene. However, deletion of the CHS1 gene did not affect the phenotype of the gas1 delta mutant and only slightly reduced the chitin content. Interestingly, in chs1 gas1 double mutants the lysed-bud phenotype, typical of chs1 null mutant, was suppressed, although in gas1 cells there was no reduction in chitinase activity. CHS3 expression was not affected in the gas1 mutant. Deletion of the CHS3 gene severely compromised the phenotype of gas1 cells, despite the fact that CSIII activity, assayed in membrane fractions, did not change. Furthermore, in chs3 gas1 cells the chitin level was about 10% that of gas1 cells. Thus, CSIII is the enzyme responsible for the hyperaccumulation of chitin in response to cell wall stress. However, the level of enzyme or the in vitro CSIII activity does not change. This result suggests that an interaction with a regulatory molecule or a posttranslational modification, which is not preserved during membrane fractionation, could be essential in vivo for the stress-induced synthesis of chitin.