Bioaccumulation of heavy elements by Armadillidium vulgare (Crustacea,Isopoda) exposed to fallout of a municipal solid waste landfill

This paper reports the response of isopods exposed to fallout of a municipal solid waste landfill located in central Italy. Soil samples and specimens of Armadillidium vulgare were collected at different distances from the landfill and analyzed to determine the concentrations of heavy elements such as As, Cd, Co, Cr, Cu, Ni, Pb, Sb, V and Zn. The isopod analysis was performed on unpurged and purged specimens. Analytical data indicate that the soil contents of heavy elements were quite uniform and within the respective local geochemical background. Slight enrichments of Cu and Pb were found in some soils collected within the solid waste. Purged isopods showed an accumulation of As, Co, Cr, Ni, Sb and V whose body levels decreased as the distance from the landfill increased. Cd, Cu, Pb and Zn concentrations in purged specimens were rather uniform and no significant variation trend occurred. This result probably was due to the fact that the isopods are provided with physiological mechanisms of regulation for these heavy elements. Analytical data also indicate the ability of A. vulgare to adsorb differently the heavy elements according to the following order: As > Co > Ni > Pb > V. The contents of heavy elements in unpurged specimens were higher than in purged ones. This finding suggested that the defecation has marked effects on the tissue levels of heavy elements in isopods. This study indicates that the isopods provide useful information about environmental quality in areas characterized by low and discontinuous emission of heavy elements and their low accumulation in soil.     

Evolution and Multiplicity of Arginine Decarboxylases in Polyamine Biosynthesis and Essential Role in Bacillus subtilis Biofilm Formation

Arginine decarboxylases (ADCs; EC 4.1.1.19) from four different protein fold families are important for polyamine biosynthesis in bacteria, archaea, and plants. Biosynthetic alanine racemase fold (AR-fold) ADC is widespread in bacteria and plants. We report the discovery and characterization of an ancestral form of the AR-fold ADC in the bacterial Chloroflexi and Bacteroidetes phyla. The ancestral AR-fold ADC lacks a large insertion found in Escherichia coli and plant AR-fold ADC and is more similar to the lysine biosynthetic enzyme meso-diaminopimelate decarboxylase, from which it has evolved. An E. coli acid-inducible ADC belonging to the aspartate aminotransferase fold (AAT-fold) is involved in acid resistance but not polyamine biosynthesis. We report here that the acid-inducible AAT-fold ADC has evolved from a shorter, ancestral biosynthetic AAT-fold ADC by fusion of a response regulator receiver domain protein to the N terminus. Ancestral biosynthetic AAT-fold ADC appears to be limited to firmicute bacteria. The phylogenetic distribution of different forms of ADC distinguishes bacteria from archaea, euryarchaeota from crenarchaeota, double-membraned from single-membraned bacteria, and firmicutes from actinobacteria. Our findings extend to eight the different enzyme forms carrying out the activity described by EC 4.1.1.19. ADC gene clustering reveals that polyamine biosynthesis employs diverse and exchangeable synthetic modules. We show that in Bacillus subtilis, ADC and polyamines are essential for biofilm formation, and this appears to be an ancient, evolutionarily conserved function of polyamines in bacteria. Also of relevance to human health, we found that arginine decarboxylation is the dominant pathway for polyamine biosynthesis in human gut microbiota.     

Gut-associated immune effector responses in immunocompetent and immunocomprimised mice with Giardia lamblia

Abstract Significantly higher Giardia lamblia trophozoites load in the intestine of infected mice accompanied pronounced influx of suppressor/cytotoxic T cells (Lyt 2.2⁺), T cells (Thy 1.2⁺) and significant reduction in IgA-containing cells in the gut during the establishment and peak phases of infection. The induction of helper/inducer T cells (Lyt 1.1⁺) and significant enhancement of IgA-containing cells in gut resulted in the decline of the trophozoite loads. However, the prior treatment of animals with dexamethasone alone resulted in significant reduction in helper/inducer T cells (Lyt 1.1⁺) and the IgA-containing cells in the gut; the percents of suppressor/cytotoxic T cells (Lyt 2.2⁺) and IgM-containing cells remained unaltered. Although the G. lamblia infection in such animals further significantly increased the influx of suppressor/cytotoxic T cells, the late response of helper/inducer T cells and IgA-containing cells was abrogated during the decline phase of infection. The significant reduction in the trophozoite load — despite immuno-suppressive therapy — appeared to be due to unaltered IgM response in such animals which probably took over the function of IgA in defense against G. lamblia . The data of the investigation thus suggested a role of helper/inducer T cells and antibodies producing cells in gut as important effector cells resulting in the termination of primary G. lamblia infection.     

Gilliamella intestini sp. nov., Gilliamella bombicola sp. nov., Gilliamella bombi sp. nov. and Gilliamella mensalis sp. nov.: Four novel Gilliamella species isolated from the bumblebee gut

Spectra of five isolates (LMG 28358^T, LMG 29879^T, LMG 29880^T, LMG 28359^T and R-53705) obtained from gut samples of wild bumblebees of Bombus pascuorum, Bombus lapidarius and Bombus terrestris were grouped into four MALDI-TOF MS clusters. RAPD analysis revealed an identical DNA fingerprint for LMG 28359^T and R-53705 which also grouped in the same MALDI-TOF MS cluster, while different DNA fingerprints were obtained for the other isolates.Comparative 16S rRNA gene sequence analysis of the four different strains identified Gilliamella apicola NCIMB 14804^T as nearest neighbour species. Average nucleotide identity values of draft genome sequences of the four isolates and of G. apicola NCIMB 14804^T were below the 96% threshold value for species delineation and all four strains and G. apicola NCIMB 14804^T were phenotypically distinct. Together, the draft genome sequences and phylogenetic and phenotypic data indicate that the four strains represent four novel Gilliamella species for which we propose the names Gilliamella intestini sp. nov., with LMG 28358^T as the type strain, Gilliamella bombicola sp. nov., with LMG 28359^T as the type strain, Gilliamella bombi sp. nov., with LMG 29879^T as the type strain and Gilliamella mensalis sp. nov., with LMG 29880^T as the type strain.     

Fluorescent histochemistry of the teleost gut: Evidence for the presence of serotonergic neurones

Summary The guts of the teleosts Myoxocephalus scorpius, Pleuronectes platessa and Clupea harengus were examined using fluorescent histochemistry and the innervation compared to that in mammals and other lower vertebrates. In Myoxocephalus and Pleuronectes both green and yellow fast fading fluorescent nerves were found in the intestine. To test whether the yellow nerves might be serotonergic, an attempt was made to extract 5-HT from the intestine of these fish in a region where enterochromaffin cells were absent. Chromatography of extracts showed the presence of 5-HT, and, in Myoxocephalus, dopamine.     

Feeding ecology of common carp (Cyprinus carpio L.) in a rice–fish culture system of the Apatani plateau (Arunachal Pradesh, India)

For two years (2002, 2003) selective feeding ecology of the common carp (Cyprinus carpio L.) has been studied in carp-integrated rice fields in Apatani Plateau of Arunachal Pradesh (India). Sampling strategy was based on the water depths in the fields and on the flood phases: early flood phase (June–July), mid flood phase (July–August), and late flood phase (September–October). In 2003 the water level was higher and therefore periphyton availability was better. This resulted in larger gut contents and better growth of the carp compared with 2002 when the water levels were lower. Gut contents analyses revealed a total of 60 food items of which 22 belonged to the Chlorophycea, 12 to the Cyanobacteria, 10 to the Bacillariophycea and 16 to several zooplankton taxa. With the progress of flood phases, the fish increased its feeding on periphyton food items; simultaneously, feeding on plankton items gradually declined. This was caused by the increasing periphyton availability on the rice-stems. Selective feeding on plankton and periphyton taxa was studied, selectivity changed with the flood phases. Periphytic Chlorophycea and Cyanobacteria, especially, were strongly positively selected. Generally, periphyton was the most important resource for the common carp in the rice fields.