The efficiency of the red alga Mastocarpus stellatus for remediation of cadmium pollution

This work reports the results of the study for cadmium binding by the dead red macroalga Mastocarpus stellatus. Kinetics sorption experiments demonstrated the high rate of metal biosorption: the system attained over 50% of the total biomass cadmium uptake within 2 min of contact and over 90% in the first 9 min. The kinetic data were successfully described by a pseudo-second order model with rate constants ranging from 1.06 to 10 gmmol(-1)min(-1), as a function of initial metal concentration and temperature. The equilibrium binding was accurately represented in terms of Langmuir and Langmuir-Freundlich models. The sorption isotherms at constant pH showed uptake values as 0.49 mmol g(-1) (at pH 2.4), 0.56 mmol g(-1) (at pH 4) and 0.59 mmol g(-1) (at pH 6), while the affinity constant values were between 0.6 and 5 mmol(-1) L (Langmuir fit). The acid-base properties of the alga were also studied, obtaining the total number of acid groups, 2.5 mmol g(-1), and their apparent pK value, 1.56, using the Katchalsky model. Desorption studies were conducted employing different HNO(3) concentrations and desorption times.     

Conservation and alteration of HLA-B27-specific T cell epitopes on mouse cells. Implications for peptide-mediated alloreactivity.

Alloreactive CTL responses generate a great variety of clonal specificities. Such diversity may be related to recognition of multiple peptides constitutively bound to any given MHC alloantigen. Among human alloreactive CTL, only a fraction of the clones lyse mouse P815 cells expressing class I HLA proteins. In this study the fine specificity of HLA-B27 allorecognition on human or mouse cells by five human HLA-B27-specific CTL clones was comparatively analyzed. This was done to examine what degree of variation in epitope structure is compatible with recognition of HLA Ag on mouse cells. Nine site-specific HLA-B27 mutants were expressed on both human and mouse cells, after DNA-mediated gene transfer, to construct two analogous series of target cells. The reaction patterns of four of the five CTL clones with these cell panels were compatible with conservation of their corresponding epitopes upon expression of HLA-B27 on mouse cells. The reaction pattern of the fifth clone was different with either cell panel, indicating that its epitope was structurally altered on mouse cells. It also suggested a selectively increased expression of the determinant on these cells. The results suggest that most of the epitopes recognized by allospecific CTL clones reacting across species are either independent of any bound peptide or involve identical peptides from both cell types. However, some of these clones recognize alloantigen-bound peptides that are somewhat different in structure depending on the cell type, and may be expressed at the mouse cell surface in greater amounts. Such peptides could arise from related proteins in both species, and be polymorphic as a result of phylogenetic divergence.     

Introgression from non-native species unveils a hidden threat to the migratory Neotropical fish <Emphasis Type="Italic">Prochilodus hartii</Emphasis>

Invasive species are one of the greatest threats to biodiversity, due to competition, predation, pathogen spread, and hybridization. The latter may remain undetected and impair the survival of species, due to genetic admixture and hybrid swarming (i.e., interbreeding between hybrid individuals and backcrossing with parental species). The impact of invasive species remains poorly studied in the Neotropical ichthyofauna, particularly when considering the potential for hybridization between native and introduced species. Due to fisheries importance and its commercial value, species of the Prochilodus genus have been introduced to other catchments in Brazil. Here, we evaluate the introduction of non-native Prochilodus species and the potential effect of hybridization with the native migratory fish P. hartii. To evaluate possible introgression of Prochilodus spp. to P. hartii in the Jequitinhonha river basin (JRB), we employed a morphogenetic approach, analysing 219 specimens sampled from a broad extent of the river basin. Morphological analyses using meristic characters were incongruent with molecular identification by DNA barcoding (COI) in 22.83% of the analysed specimens. Haplotypes from three non-native species (P. argenteus, P. costatus, and P. lineatus) were recovered from specimens morphologically identified as P. hartii. Hybridization between P. hartii and introduced species was confirmed using co-dominant nuclear microsatellite markers. We observed a pronounced introgression pattern in this Neotropical basin, and paradoxically, despite being one of the most abundant migratory species native to the JRB, due to ongoing levels of introgression, P. hartii’s genetic integrity and conservation might be affected.     

Syrphid predators (Dipt.: Syrphidae) of gall forming aphids (Hom.: Aphididae) in mediterranean areas: implications for biological control of fruit trees pests

Most syrphids feeding on gall forming aphids belong to Pipizini tribe. The biology of two species relatively abundant in Mediterranean areas of Southeastern Spain,Pipiza festiva Meigen, 1822 andHeringia heringii (Zetterstedt, 1843), is given after 3 years of detailed survey. In this paper we study the relationship of both species of syrphids with the gall-forming aphids associated with trees of the genusPistacia (Anacardiaceae). We also establish the relationship syrphid-aphid-fruit tree, the relative abundance in each crop, length of preimaginal stages, aphid-specificity and parasitism. At last we show the seasonal adaptations of these hoverflies and their role in biological control of some fruit tree aphid pests.     

Autotrophic and Heterotrophic Picoplankton in Wetlands: Differences with Lake Patterns

This study describes the occurrence, importance and seasonal patterns of picoplankton in two wetlands (TDNP and La Safor), and compares them to a system of fifteen interconnected lakes (Ruidera). In TDNP we performed a six‐year monthly study in three sites of the wetland. Bacterial abundance increased throughout time and the autotrophic picoplankton (APP) range was wide (up to 33 × 10⁶ cells/ml). The annual averaged APP contribution to total picoplankton and phytoplankton biovolumes was 0.5–22% and 0.03–6% respectively. There were large differences among sites in terms of APP absolute and relative abundance and seasonal patterns. In La Safor, the APP relative contribution to picoplankton and phytoplankton biovolumes was 0–25% and 0–40%, respectively, while in the Ruidera lakes was 0–47% and 0–5%, respectively. In the three systems there was a significant correlation between bacterial abundance and chlorophyll a but the slopes of the linear regressions were different. No significant relationships were found of APP abundance and trophic status in the wetlands, but were noted in the lake system. There was no clear relationship of APP contribution to total phytoplankton biomass to the trophic gradient in wetlands. In the lakes, the higher contribution of APP was found in those with higher trophic levels.