Cupriavidus necator isolates are able to fix nitrogen in symbiosis with different legume species

The aim of the present study was to identify a collection of 35 Cupriavidus isolates at the species level and to examine their capacity to nodulate and fix N(2). These isolates were previously obtained from the root nodules of two promiscuous trap species, Phaseolus vulgaris and Leucaena leucocephala, inoculated with soil samples collected near Sesbania virgata plants growing in Minas Gerais (Brazil) pastures. Phenotypic and genotypic methods applied for this study were SDS-PAGE of whole-cell proteins, and 16S rRNA and gyrB gene sequencing. To confirm the ability to nodulate and fix N(2), the presence of the nodC and nifH genes was also determined, and an experiment was carried out with two representative isolates in order to authenticate them as legume nodule symbionts. All 35 isolates belonged to the betaproteobacterium Cupriavidus necator, they possessed the nodC and nifH genes, and two representative isolates were able to nodulate five different promiscuous legume species: Mimosa caesalpiniaefolia, L. leucocephala, Macroptilium atropurpureum, P. vulgaris and Vigna unguiculata. This is the first study to demonstrate that C. necator can nodulate legume species.     

Polyembryony increases embryo and seedling mortality but also enhances seed individual survival in Handroanthus species (Bignoniaceae)

Polyembryony seems to be advantageous to mother plants in detriment of their siblings which face competition since the beginning of seed development. This competition may limit the turnover of embryos into seedlings and their survival ability. We analysed polyembryony frequency and embryo to seedling turnover in three Handroanthus species with sporophytic apomixis. We tested if the embryo number per seed affected seed and embryo morphometry, seedling survival ability and seed individual survival (i.e. survival of at least one seedling per seed). The number of embryos per seed was compared with seedling number at different developmental stages. All 14 populations showed high frequencies of polyembryonic seeds (21–91%). As the number of embryos per seed increased (up to eight embryos/seed), there was a reduction of mean embryo mass, area, seedling length, individual seedling survival ability, and embryo to seedling turnover. There was also an increase in embryo morphological anomalies. However, enhanced seed individual survival was also observed. Thus, the high frequency of polyembryonic seeds and the increase in seed individual survival support the idea that polyembryony represents an alternative reproductive mechanism which can favours these species.     

Immune response and protective efficacy of S9 ribosomal protein of Streptococcus pneumoniae in a model of sepsis

Vaccination is the most promising strategy to reduce the incidence of pneumococcal infection. Although there are vaccines available, all of them are based on polysaccharide antigens (conjugated or not). In addition to their high cost, those vaccines do not cover all serotypes. To overcome these hindrances, we evaluated the immunogenicity and the protective efficacy of the S9 ribosomal protein of Streptococcus pneumoniae with the aim of developing a protein-based vaccine in the future. The gene encoding the S9 ribosomal protein was cloned in pET21-a expression vector, and the recombinant S9 protein was used to immunize mice. Significantly higher levels of anti-S9 immunoglobulin G were achieved (with predominance of immunoglobulin G1) in comparison with the control. Antibodies elicited against S.?pneumoniae protein extract in rabbit recognized the recombinant S9 protein by Western blot, thus demonstrating its immunogenicity. Moreover, mice immunized with recombinant S9 protein and challenged with a virulent strain of S.?pneumoniae presented a significant reduction of bacteremia after 24?h of infection as compared with the control. However, in the S9-immunized mice the onset of death was insignificantly delayed, but all of them died by the fourth day postinfection.     

Active site mutants of human secreted Group IIA Phospholipase A2 lacking hydrolytic activity retain their bactericidal effect

The Human Secreted Group IIA Phospholipase A₂ (hsPLA2GIIA) presents potent bactericidal activity, and is considered to contribute to the acute-phase immune response. Hydrolysis of inner membrane phospholipids is suggested to underlie the bactericidal activity, and we have evaluated this proposal by comparing catalytic activity with bactericidal and liposome membrane damaging effects of the G30S, H48Q and D49K hsPLA2GIIA mutants. All mutants showed severely impaired hydrolytic activities against mixed DOPC:DOPG liposome membranes, however the bactericidal effect against Micrococcus luteus was less affected, with 50% killing at concentrations of 1, 3, 7 and 9 μg/mL for the wild-type, D49K, H48Q and G30S mutants respectively. Furthermore, all proteins showed Ca²⁺-independent damaging activity against liposome membranes demonstrating that in addition to the hydrolysis-dependent membrane damage, the hsPLA2GIIA presents a mechanism for permeabilization of phospholipid bilayers that is independent of catalytic activity, which may play a role in the bactericidal function of the protein     

Heavy Metals in Hair of Wild Canids from the Brazilian Cerrado

In this study, we aimed to assess whether free-ranging wild canids are exposed to heavy metals in one of the most developed and populated regions of Brazil. Hair of 26 wild canids (maned wolves Chrysocyon brachyurus, crab-eating foxes Cerdocyon thous, and hoary foxes Lycalopex vetulus) from the Cerrado biome in Southeast Brazil were analyzed by spectrophotometry to detect cadmium, chromium, and lead, and also the essential copper, iron, manganese, and zinc traces. All samples showed traces of copper, iron, manganese, and zinc. Non-essential lead was detected in 57% (2.35 ± 0.99 mg/kg), and chromium in 88% (2.98 ± 1.56 mg/kg) of samples. Cadmium traces (detection limit 0.8 mg/kg) were not found. Crab-eating foxes had more copper, iron, and manganese in hair than maned wolves. Correlations among element levels differed between maned wolves and crab-eating foxes. Concentrations of chromium and lead were outstandingly higher than in wild canids from other areas. Addressing the causes of such levels and the impacts of the heavy metal pollution in Neotropical ecosystems is urgent for animal health and conservation purposes. We argue that heavy metal pollution should be considered as dangerous threats to wildlife health in Brazil and recommend hair sampling as a biomonitoring tool for heavy metals in Neotropical terrestrial mammals.     

Genetic polymorphism in Taenia solium metacestodes from different Brazilian geographic areas

The aim of the present study is to investigate genetic polymorphisms in Taenia solium metacestodes from different Brazilian geographical areas and to relate them to antibody recognition in serum samples of neurocysticercosis (NC) patients. Metacestodes were obtained from the Distrito Federal (DF), Bahia, Minas Gerais (MG) and S?o Paulo (SP) regions of Brazil. Samples of human sera from 49 individuals with NC, 68 individuals with other helminthiasis and 40 healthy volunteers were analysed (157 individuals in total). Antigens were prepared and used in enzyme-linked immunosorbent assay and western blotting assays to detect specific immunoglobulin G antibodies. Genetic distances between metacestode populations were analysed using random amplified polymorphic DNA (RAPD) analysis. Our results show that there was a higher frequency of reactivity in the DF region in the sera from NC patients (p < 0.05), while discrimination between active and inactive NC was seen only in extracts from the MG and SP regions (p < 0.05). Using RAPD, the sample from the DF region presented a greater increase compared to the other regions. A relationship between genetic polymorphisms among T. solium metacestodes from different areas in Brazil and the differences in antibody detection in patients with NC were established.     

The impact of highly active antiretroviral therapy on the survival of vertically HIV-infected children and adolescents in Belo Horizonte, Brazil

The use of highly active antiretroviral therapy (HAART) for human immunodeficiency virus (HIV)-infected patients has reduced the number of acquired immune deficiency syndrome-related deaths worldwide. This study assessed the impact of HAART on the survival and death rates of vertically HIV-infected children and adolescents in Belo Horizonte, Brazil. Data were obtained from a historic cohort of vertically HIV-infected children and adolescents aged zero-19 years old who were admitted from March 1989-December 2004 and were followed until June 2006. Patients who used HAART were included if they were treated for at least 12 weeks. Of 359 patients, 320 patients met the inclusion criteria. The overall mortality rate was 9.7% [31/320; 95% confidence interval (CI): 6.0-13%]. The median survival for the non-HAART and HAART groups was 31.5 and 55.9 months, respectively (log rank = 22.11, p < 0.0001). In the multivariate analysis, the statistically significant variables were HAART and the weight-for-age Z score < -2, with HAART constituting a protective factor [relative risk (RR): 0.13; CI 95%: 0.05-0.33] and malnutrition constituting a risk factor (RR: 3.44; CI 95%: 1.60-7.40) for death. The incidence of death was 5.1/100 person-years in the non-HAART group and 0.8/100 person-years in the HAART group (p < 0.0001).     

Arbuscular mycorrhiza confers Pb tolerance in <Emphasis Type="Italic">Calopogonium mucunoides</Emphasis>

Heavy metals (HMs) are environmental pollutants of great concern to humans because of their high potential toxicity. Lead is a HM that is present in the soil in very small amounts, but anthropogenic activities have increased its content in some locations, which can make these areas unproductive or inappropriate for crop production. However, there are some plants that can grow in contaminated soils and, thus, can be useful for the removal or stabilisation of such contaminants. In addition, plants that are not able to tolerate high concentrations of HMs in the soil can become tolerant or increase their performance when associated with arbuscular mycorrhizal (AM) fungi. Accordingly, this study was carried out to verify whether the inoculation of Glomus etunicatum, an AM fungus species, in Calopogonium mucunoides would influence plant tolerance to increasing concentrations of Pb in the soil. The experimental design was completely randomised, in a 2 × 4 factorial design, and the treatments consisted of inoculation (or not) with the AM fungus, G. etunicatum, and the addition of four Pb concentrations (0, 250, 500 or 1,000 mg kg⁻¹) to the soil. The results showed that the association of C. mucunoides with G. etunicatum promoted biomass production, and nutrient uptake (P, S and Fe) was also positively influenced by mycorrhization. The malondialdehyde content was higher in non-mycorrhizal leaves, suggesting a reduction in the damage to membranes by lipid peroxidation in plants associated with mycorrhizae. However, the Pb concentration in the shoots did not differ between the mycorrhizal and non-mycorrhizal plants. The results of our study suggest that the AM symbiosis can be considered very effective in contributing to the tolerance of C. mucunoides to Pb.