Physiological responses to Cd and Zn in two Cd/Zn hyperaccumulating Thlaspi species

In a model hyperaccumulation study a Cd/Zn hyperaccumulator Thlaspi caerulescens accession Ganges and a recently reported Cd/Zn hyperaccumulator Thlaspi praecox grown in increasing Cd and Zn concentrations in the substrate and in field collected polluted soil were compared. Plant biomass, concentrations of Cd and Zn, total chlorophylls and anthocyanins, antioxidative stress parameters and activities of selected antioxidative enzymes were compared. Increasing Cd, but not Zn in the substrate resulted in the increase of biomass of roots and shoots of T. praecox and T. caerulescens. The two species hyperaccumulated Cd in the shoots to a similar extent, whereas T. caerulescens accumulated more Zn in the shoots than T. praecox. Cadmium amendment decreased total chlorophyll concentration and glutathione reductase activity, and increased non-protein thiols concentration only in T. praecox, suggesting that it is less tolerant to Cd than T. caerulescens. In the field-contaminated soil, T. caerulescens accumulated higher Cd concentrations; but as T. praecox produced higher biomass, both species have similar ability to extract Cd.     

Technical evaluation of nested PCR for the diagnosis of experimental sporotrichosis

BackgroundSporotrichosis caused by the dimorphic fungus Sporothrix schenckii can presents in a variety of clinical forms. Routine diagnosis is made by mycology and serology studies. Few investigations have been focused on the evaluation of the molecular diagnosis.AimTo determine the value of the nested PCR technique for the diagnosis of experimental sporotrichosis in organs of mice, and to compare the results with the established laboratory diagnostic procedures.MethodsBALB/c mice were inoculated with growing concentrations of the 2 morphological phases of the fungus. The infected animals were sacrificed one month later and specimens from liver, spleen, lung and testicle were obtained to perform wet mount, culture and molecular diagnosis by the nested PCR technique. Blood samples were obtained for determination of specific antibodies against S. schenckii by the double immunodiffusion procedure.ResultsThe pathogenicity observed with the different concentrations of the fungus inoculated and its isolation by culture, showed scarce differences in the study of specimens from organs infected with the 2 morphological phases of S. schenckii. Specimens from organs of mice inoculated with the mycelial phase when studied by wet mount and culture, showed a higher positivity (100 and 37.5%) than those from mice inoculated with the yeast phase (73 and 2%). However, diagnosis by the nested PCR molecular technique applied to the latter specimens showed a higher percentage of positivity (75%) and 43% of positive results coming from animals infected with the mycelial phase. Specific antibody detection was positive in 100% all groups of infected mice.ConclusionsIn the study of experimental sporotrichosis in mice, the culture, as well as the antibody detection, was an effective diagnostic procedure, while the nested PCR and microscopic studies had a lower diagnostic value.     

Four anti-protozoal and anti-bacterial compounds from Tapirira guianensis

Tapirira guianensis is a common tree used in traditional medicine in French Guiana against several infectious diseases (malaria, leishmaniasis, bacteria, etc.). The bioassay-guided purification of CH₂Cl₂ bark extract led to the isolation of four cyclic alkyl polyol derivatives: 4,6,2′-trihydroxy-6-[10′(Z)-heptadecenyl]-1-cyclohexen-2-one (1a), 1,4,6-trihydroxy-1,2′-epoxy-6-[10′(Z)-heptadecenyl]-2-cyclohexene (1b), 1,4,5,2′-tetrahydroxy-1-[10′(Z)-heptadecenyl]-2-cyclohexene (2), and 1,3,4,6-tetrahydroxy-1,2′-epoxy-6-[10′(Z)-heptadecenyl]-cyclohexane (3). The structures were established on the basis of 1D and 2D NMR analyses. The anti-leishmanial, anti-plasmodial, anti-bacterial (on Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli), and anti-fungal (on Candida albicans) activities of the extracts and of these original compounds were evaluated. Two showed medicinal interest supporting the traditional uses of the plant. The structures were established through spectral analyses of the isolates and their derivatives.     

Leaf Litter Fuels Methanogenesis Throughout Decomposition in a Forested Peatland

Decomposing leaf litter is a large supply of energy and nutrients for soil microorganisms. How long decaying leaves continue to fuel anaerobic microbial activity in wetland ecosystems is poorly understood. Here, we compare leaf litter from 15 tree species with different growth forms (angiosperms and gymnosperms, deciduous, and longer life span), using litterbags positioned for up to 4 years in a forested peatland in New York State. Periodically, we incubated partially decayed residue per species with fresh soil to assess its ability to fuel microbial methane (CH₄) production and concomitant anaerobic carbon dioxide (CO₂) production. Decay rates varied by leaf type: deciduous angiosperm > evergreen gymnosperm > deciduous gymnosperm. Decay rates were slower in leaf litter with a large concentration of lignin. Soil with residue of leaves decomposed for 338 days had greater rates of CH₄ production (5.8 µmol g^?1 dry mass d^?1) than less decomposed (<0.42 µmol g^?1 dry mass d^?1) or more decomposed (2.1 µmol g^?1 dry mass d^?1) leaf residue. Species-driven differences in their ability to fuel CH₄ production were evident throughout the study, whereas concomitant rates of CO₂ production were more similar among species and declined with degree of decomposition. Methane production rates exhibited a positive correlation with pectin and the rate of pectin decomposition. This link between leaf litter decay rates, biochemical components in leaves, and microorganisms producing greenhouse gases should improve predictions of CH₄ production in wetlands.     

Molecular characterisation of Mycobacterium tuberculosis isolates in the First National Survey of Anti-tuberculosis Drug Resistance from Venezuela

Background

Molecular typing of Mycobacterium tuberculosis strains has become a valuable tool in the epidemiology of tuberculosis (TB) by allowing detection of outbreaks, tracking of epidemics, identification of genotypes and transmission events among patients who would have remained undetected by conventional contact investigation. This is the first genetic biodiversity study of M. tuberculosis in Venezuela. Thus, we investigated the genetic patterns of strains isolated in the first survey of anti-tuberculosis drug-resistance realised as part of the Global Project of Anti-tuberculosis Drug Resistance Surveillance (WHO/IUATLD).

Results

Clinical isolates (670/873) were genotyped by spoligotyping. The results were compared with the international spoligotyping database (SpolDB4). Multidrug resistant (MDR) strains (14/18) were also analysed by IS6110-RFLP assays, and resistance to isoniazid and rifampicin was characterised. Spoligotyping grouped 82% (548/670) of the strains into 59 clusters. Twenty new spoligotypes (SITs) specific to Venezuela were identified. Eight new inter-regional clusters were created. The Beijing genotype was not found. The genetic network shows that the Latin American and Mediterranean family constitutes the backbone of the genetic TB population-structure in Venezuela, responsible of >60% of total TB cases studied. MDR was 0.5% in never treated patients and 13.5% in previously treated patients. Mutations in rpoB gene and katG genes were detected in 64% and 43% of the MDR strains, respectively. Two clusters were found to be identical by the four different analysis methods, presumably representing cases of recent transmission of MDR tuberculosis.

Conclusion

This study gives a first overview of the M. tuberculosis strains circulating in Venezuela during the first survey of anti-tuberculosis drug-resistance. It may aid in the creation of a national database that will be a valuable support for further studies.     

Effects of the entomopathogenic fungus Neozygites tanajoae and the predatory mite Typhlodromalus aripo on cassava green mite densities: screenhouse experiments

To improve biocontrol of the cassava green mite, Mononychellus tanajoa, a series of screenhouse experiments were conducted on cassava to determine the effects of single and combined releases of the predatory mite Typhlodromalus aripo and the entomopathogenic fungus Neozygites tanajoae on the suppression of M. tanajoa. We showed that, separately or in combination, T. aripo and N. tanajoae significantly reduced M. tanajoa populations. Moreover, combined release of T. aripo and N. tanajoae on the same cassava plants improved M. tanajoa control. However, our data suggest between T. aripo and N. tanajoae an asymmetric competition that significantly affected N. tanajoae only. This interference is indirect, probably mediated by their common prey or host mite, M. tanajoa since N. tanajoae is not pathogenic to T. aripo. We conclude that adding N. tanajoae to T. aripo populations in Africa would not negatively affect T. aripo and would further promote biocontrol of M. tanajoa.     

Tetrahydrohyperforin Inhibits the Proteolytic Processing of Amyloid Precursor Protein and Enhances Its Degradation by Atg5-Dependent Autophagy

Alzheimer''s disease (AD) is a neurodegenerative disorder characterized by the accumulation of amyloid-β (Aβ) peptide. We have previously shown that the compound tetrahydrohyperforin (IDN5706) prevents accumulation of Aβ species in an in vivo model of AD, however the mechanism that explains this reduction is not well understood. We show herein that IDN5706 decreases the levels of ER degradation enhancer, mannosidase alpha-like 1 (EDEM1), a key chaperone related to endoplasmic-reticulum-associated degradation (ERAD). Moreover, we observed that low levels of EDEM1 correlated with a strong activation of autophagy, suggesting a crosstalk between these two pathways. We observed that IDN5706 perturbs the glycosylation and proteolytic processing of the amyloid precursor protein (APP), resulting in the accumulation of immature APP (iAPP) in the endoplasmic reticulum. To investigate the contribution of autophagy, we tested the effect of IDN5706 in Atg5-depleted cells. We found that depletion of Atg5 enhanced the accumulation of iAPP in response to IDN5706 by slowing down its degradation. Our findings reveal that IDN5706 promotes degradation of iAPP via the activation of Atg5-dependent autophagy, shedding light on the mechanism that may contribute to the reduction of Aβ production in vivo.     

Ceramide kinase is required for a normal eicosanoid response and the subsequent orderly migration of fibroblasts

In these studies, the role of ceramide-1-phosphate (C1P) in the wound-healing process was investigated. Specifically, fibroblasts isolated from mice with the known anabolic enzyme for C1P, ceramide kinase (CERK), ablated (CERK^−/− mice) and their wild-type littermates (CERK^+/+) were subjected to in vitro wound-healing assays. Simulation of mechanical trauma of a wound by scratching a monolayer of fibroblasts from CERK^+/+ mice demonstrated steadily increasing levels of arachidonic acid in a time-dependent manner in stark contrast to CERK^−/− fibroblasts. This observed difference was reflected in scratch-induced eicosanoid levels. Similar, but somewhat less intense, changes were observed in a more complex system utilizing skin biopsies obtained from CERK-null mice. Importantly, C1P levels increased during the early stages of human wound healing correlating with the transition from the inflammatory stage to the peak of the fibroplasia stage (e.g., proliferation and migration of fibroblasts). Finally, the loss of proper eicosanoid response translated into an abnormal migration pattern for the fibroblasts isolated from CERK^−/−. As the proper migration of fibroblasts is one of the necessary steps of wound healing, these studies demonstrate a novel requirement for the CERK-derived C1P in the proper healing response of wounds.