Comparative efficiency of algal biofilters in the removal of chromium and copper from wastewater

The performance of a macroalgae (Sargassum sp.), a laboratory-cultivated microalgae (Chlorococcum sp.) and a commercially available granulated activated carbon (GAC) for the removal of copper (Cu) and chromium (Cr) from aqueous solutions was evaluated using batch experiments. Kinetic and isotherm experiments were done at the optimal pH of 4.5 ± 0.1 for Cu (II) and 2.0 ± 0.1 for Cr (total). The equilibrium isotherms were determined and the results were analyzed using the Langmuir and Freundlich models. The best Cu removal performance was observed on Sargassum at a maximum removal of 87.3% obtained for an initial concentration of 20 mg L^?1 Cu. The maximum uptake capacities for Cu (II) were 71.4, 19.3 and 11.4 mg g^?1 of Sargassum, Chlorococcum and GAC, respectively. The biosorbents were also able to remove appreciable amounts of Cr, again with Sargassum showing maximum uptake capacity over the other materials. Kinetic studies also reveal that the removal rate is faster for both metals in Sargassum. Tests with an actual wastewater confirm the maximum uptake capacity of Cu by Sargassum. In all experiments the Sargassum biofilter outperformed GAC, which makes it a promising low-cost alternative to conventional filtration materials for wastewater treatment.     

mTORC2 can associate with ribosomes to promote cotranslational phosphorylation and stability of nascent Akt polypeptide

The mechanisms that couple translation and protein processing are poorly understood in higher eukaryotes. Although mammalian target of rapamycin (mTOR) complex 1 (mTORC1) controls translation initiation, the function of mTORC2 in protein synthesis remains to be defined. In this study, we find that mTORC2 can colocalize with actively translating ribosomes and can stably interact with rpL23a, a large ribosomal subunit protein present at the tunnel exit. Exclusively during translation of Akt, mTORC2 mediates phosphorylation of the nascent polypeptide at the turn motif (TM) site, Thr450, to avoid cotranslational Akt ubiquitination. Constitutive TM phosphorylation occurs because the TM site is accessible, whereas the hydrophobic motif (Ser473) site is concealed in the ribosomal tunnel. Thus, mTORC2 can function cotranslationally by phosphorylating residues in nascent chains that are critical to attain proper conformation. Our findings reveal that mTOR links protein production with quality control.     

Study of the antibody response against Mycobacterium tuberculosis antigens in Warao Amerindian children in Venezuela

This study was aimed at investigating alternate methods for serodiagnosis of tuberculosis (TB), which are needed because bacteriologic diagnosis of childhood TB is difficult. A selection of 80 serum and saliva samples were tested from Warao indigenous children under 15 years of age; 34 high TB suspects (28 positive and 6 negative for the tuberculin skin test, TST) and 46 healthy contact children (32 positive and 14 negative for the TST). Several enzyme-linked immunosorbent assay (ELISA) serological tests were developed to test for Mycobacterium tuberculosis-specific antibodies, including serum IgA, IgG, IgE, and secretory IgA (sIgA) in saliva against 3 specific antigens (PPD, HSP60, 38 kDa). Of these, 2 antigens, PPD and 38 kDa, showed significantly higher reactivity. The sensitivity and specificity of these tests for diagnosis remained limited, between 26.5% and 38.2%, and 77.4% and 97%, respectively. Of all the samples studied and combinations realized between all isotypes and antigens combined with 3 isotypes (anti-PPD IgG, IgE, and anti-38kDa sIgA) managed to detect the largest number of patients, showing an improved sensitivity level of 64.7%, although specificity levels dropped to 81.8%. These results were compared with the Omega diagnostics commercial kit results. The commercial kits showed significantly lower reactivity (sensitivity of 20% and 13.33% to Myco G and Complex Plus, respectively) and a specificity of 100%. This study shows that in indigenous populations of Venezuela, where invasive procedures cannot be used to select samples but evaluation with a chest X-ray for radiological studies is available, the combination of 3 specific isotypes may be a useful tool to increase diagnostic accuracy with pulmonary TB in this population, when used together with clinical and epidemiological criteria.     

Accumulation of chloroplast-targeted lipoxygenase in passion fruit leaves in response to methyl jasmonate

Wounding caused local and systemic induction of lipoxygenase (LOX) activity in passion fruit (Passiflora edulis f. flavicarpa) leaves, while exposing intact plants to methyl jasmonate (MJ) vapor provoked a much stronger response. Western blot analysis of these leaf protein extracts using polyclonal antibodies against cucumber LOX, revealed an accumulation of a 90 kDa protein, consistent with LOX enzymatic assays. The inducible LOX was purified to apparent homogeneity, and in vitro analysis of LOXactivity using linoleic acid as substrate showed that it possesses C-13 specificity. Immunocytochemical localization studies using leaf tissue from MJ-treated plants demonstrated that the inducible LOX was compartmented in large quantities in the chloroplasts of mesophyll cells, associated with the stroma. The results suggest that the wound response in passion fruit plants may be mediated by a chloroplast 13-LOX, a key enzyme of the octadecanoid defense-signaling pathway.     

Cotton rats (Sigmodon hispidus) and black rats (Rattus rattus) as possible reservoirs of Leishmania spp. in Lara State,Venezuela

A total of 519 wild animals belonging to eleven species were collected during a two year study in a cutaneous leishmaniasis endemic area in Venezuela (La Matica, Lara State). The animals were captured in home-made Tomahawk-like traps baited with maize, bananas or other available local fruits, and parasites were isolated from 27 specimens. Two different species were found naturally infected with flagellates, i.e., cotton rats (Sigmodon hispidus) and black rats (Rattus rattus). Characterization of the parasites using PCR, kDNA restriction pattern and hybridization with species-specific probes revealed the presence of Leishmania (L.) mexicana in three of the black rats and Leishmania (V.) braziliensis in two others. The latter species was also identified in the single positive specimen of S. hispidus. The results suggested both species of animals as possible reservoirs of Leishmania sp.     

Isolation of Leishmania infantum, zymodeme MON-1 from canine and human visceral leishmaniasis on Margarita Island, Venezuela.

An increase in the incidence of human visceral leishmaniasis (HVL) has been detected in recent years on Margarita Island, located off the NE coast of Venezuela. Recent studies have revealed reactivity to rK39 antigen (Leishmania chagasi) in 20% of 541 sera from domestic dogs in endemic communities; PCR reactions were positive using primers for the L. donovani complex. Here we report that isolates from human and canine infection, identified by isoenzyme analysis, correspond to L. infantum, zymodeme MON-1. This appears to be the first isolation and identification of an isolate from HVL on Margarita Island and demonstrates the presence of this zymodeme in the canine population.     

The cadherin superfamily in Anopheles gambiae: a comparative study with Drosophila melanogaster

The cadherin superfamily is a diverse and multifunctional group of proteins with extensive representation across genomes of phylogenetically distant species that is involved in cell-cell communication and adhesion. The mosquito Anopheles gambiae is an emerging model organism for the study of innate immunity and host-pathogen interactions, where the malaria parasite induces a profound rearrangement of the actin cytoskeleton at critical stages of infection. We have used bioinformatics tools to retrieve present sequence knowledge about the complete repertoire of cadherins in A. gambiae and compared it to that of the fruit fly, Drosophila melanogaster. In A. gambiae, we have identified 43 genes coding for cadherin extracellular domains that were re-annotated to 38 genes and represent an expansion of this gene family in comparison to other invertebrate organisms. The majority of Drosophila cadherins show a 1 : 1 Anopheles orthologue, but we have observed a remarkable expansion in some groups in A. gambiae, such as N-cadherins, that were recently shown to have a role in the olfactory system of the fruit fly. In vivo dsRNA silencing of overrepresented genes in A. gambiae and other genes showing expression at critical tissues for parasite infection will likely advance our understanding of the problems of host preference and hostpathogen interactions in this mosquito species.     

DRhoGEF2 regulates cellular tension and cell pulsations in the Amnioserosa during Drosophila dorsal closure

Coordination of apical constriction in epithelial sheets is a fundamental process during embryogenesis. Here, we show that DRhoGEF2 is a key regulator of apical pulsation and constriction of amnioserosal cells during Drosophila dorsal closure. Amnioserosal cells mutant for DRhoGEF2 exhibit a consistent decrease in amnioserosa pulsations whereas overexpression of DRhoGEF2 in this tissue leads to an increase in the contraction time of pulsations. We probed the physical properties of the amnioserosa to show that the average tension in DRhoGEF2 mutant cells is lower than wild-type and that overexpression of DRhoGEF2 results in a tissue that is more solid-like than wild-type. We also observe that in the DRhoGEF2 overexpressing cells there is a dramatic increase of apical actomyosin coalescence that can contribute to the generation of more contractile forces, leading to amnioserosal cells with smaller apical surface than wild-type. Conversely, in DRhoGEF2 mutants, the apical actomyosin coalescence is impaired. These results identify DRhoGEF2 as an upstream regulator of the actomyosin contractile machinery that drives amnioserosa cells pulsations and apical constriction.