Effect of age on body distribution of Tityustoxin from Tityus serrulatus scorpion venom in rats

Previous research from our Laboratory has shown a greater susceptibility of young animals, when compared to adults, to envenomation by tityustoxin (TsTX), one of the main toxins from Tityus serrulatus scorpion venom. Our hypothesis is that a differential body distribution of TsTX among adult and young animals could account for the worse prognosis of scorpion envenomation in infants. Thus, TsTX labeled with technetium-99m was injected (6 microg, subcutaneous) in adult (150-160 day-old) and young (21-22 day-old) male rats. Groups of animals were sacrificed at different times after TsTX injection (0.08, 1.0, 3.0, 6.0, 12.0 and 24.0 hours) under Urethane anesthesia (140 mg/100 g, i.p.). The brain, heart, lungs, liver, kidneys, spleen and thyroid were excised and blood collected. Young rats presented a shorter latency toxin concentration peak in all studied organs except for the liver and the kidney, when compared to adults. The ratio between the area under the curve of the toxin concentration in each organ and that in blood (Kp) indicates higher accumulation in the organs of young animals mainly for brain, liver and heart. These observations suggest a faster toxin distribution in the organs of young rats. The higher uptake of TsTX in the brain is suggestive of a greater permeability for the toxin along the blood-brain barrier of young rats. In conclusion, the higher uptake in heart, together with data from the brain, may help to elucidate the clinical manifestations frequently observed in children under scorpion envenomation.     

Diversity and symbiotic effectiveness of beta-rhizobia isolated from sub-tropical legumes of a Brazilian Araucaria Forest

While the occurrence of Betaproteobacteria occupying the nodules of tropical legumes has been shown, little is known about subtropical areas. Araucaria Forest is a subtropical endangered ecosystem, and a better understanding of the legume-rhizobial symbionts may allow their use in land reclamation. The 16S rRNA gene of bacteria isolated from nine leguminous species was sequenced and their nodulation tested in Mimosa scabrella and Phaseolus vulgaris. 196 isolates were identified as eight genotypes: Pantoea, Pseudomonas, Bradyrhizobium sp1-2, Rhizobium, and Burkholderia sp1-3. The majority of the isolates from native plants (87 %) were taxonomically related to β-rhizobia, namely Burkholderia, however the legumes Galactia crassifolia and Collea speciosa were nodulated by both α and β-rhizobia, and Acacia dealbata, an exotic plant, only by α-rhizobia. The nifH genes of some isolates were sequenced and N-fixing potential shown by the acetylene reduction test. Most of the isolates nodulated the test plants, some were effective in M. scabrella, but all presented low efficiency in the exotic promiscuous legume P. vulgaris. Pantoea and Pseudomonas did not nodulate and probably are endophytic bacteria. The presented data shows diversity of α, β and γ-Proteobacteria in nodules of subtropical legumes, and suggests host specificity with β-rhizobia. Potential isolates were found for M. scabrella, indicating that a high N-fixing strain may be further inoculated in plants for use in reforestation.     

Effects of Ethanol and Other Alkanols on Transport of Acetic Acid in Saccharomyces cerevisiae

In glucose-grown cells of Saccharomyces cerevisiae IGC 4072, acetic acid enters only by simple diffusion of the undissociated acid. In these cells, ethanol and other alkanols enhanced the passive influx of labelled acetic acid. The influx of the acid followed first-order kinetics with a rate constant that increased exponentially with the alcohol concentration, and an exponential enhancement constant for each alkanol was estimated. The intracellular concentration of labelled acetic acid was also enhanced by alkanols, and the effect increased exponentially with alcohol concentration. Acetic acid is transported across the plasma membrane of acetic acid-, lactic acid-, and ethanol-grown cells by acetate-proton symports. We found that in these cells ethanol and butanol inhibited the transport of labelled acetic acid in a noncompetitive way; the maximum transport velocity decreased with alcohol concentration, while the affinity of the system for acetate was not significantly affected by the alcohol. Semilog plots of V_max versus alcohol concentration yielded straight lines with negative slopes from which estimates of the inhibition constant for each alkanol could be obtained. The intracellular concentration of labelled acid was significantly reduced in the presence of ethanol or butanol, and the effect increased with the alcohol concentration. We postulate that the absence of an operational carrier for acetate in glucose-grown cells of S. cerevisiae, combined with the relatively high permeability of the plasma membrane for the undissociated acid and the inability of the organism to metabolize acetic acid, could be one of the reasons why this species exhibits low tolerance to acidic environments containing ethanol.     

IFNG +874 T>A single nucleotide polymorphism is associated with leprosy among Brazilians

Leprosy is a chronic infectious disease caused by Mycobacterium leprae, a low virulence mycobacterium, and the outcome of disease is dependent on the host genetics for either susceptibility per se or severity. The IFNG gene codes for interferon-γ (IFN-γ), a cytokine that plays a key role in host defense against intracellular pathogens. Indeed, single nucleotide polymorphisms (SNPs) in IFNG have been evaluated in several genetic epidemiological studies, and the SNP +874T>A, the +874T allele, more specifically, has been associated with protection against infectious diseases, especially tuberculosis. Here, we evaluated the association of the IFNG locus with leprosy enrolling 2,125 Brazilian subjects. First, we conducted a case–control study with subjects recruited from the state of São Paulo, using the +874 T>A (rs2430561), +2109 A>G (rs1861494) and rs2069727 SNPs. Then, a second study including 1,370 individuals from Rio de Janeiro was conducted. Results of the case–control studies have shown a protective effect for +874T carriers (OR_adjusted = 0.75; p = 0.005 for both studies combined), which was corroborated when these studies were compared with literature data. No association was found between the SNP +874T>A and the quantitative Mitsuda response. Nevertheless, the spontaneous IFN-γ release by peripheral blood mononuclear cells was higher among +874T carriers. The results shown here along with a previously reported meta-analysis of tuberculosis studies indicate that the SNP +874T>A plays a role in resistance to mycobacterial diseases.     

Brazilian genetic database of chromosome X

The X chromosome is a singular source of information in population genetics, anthropological research and in forensic cases. Thus, many researchers have been interested in characterizing X chromosome markers in different populations. The Brazilian Genetic Database of Chromosome X (BGBX—Banco Genético Brasileiro do Cromossomo X) website is freely available in Portuguese and English versions and was developed with the main purpose of compiling all Brazilian population genetic data for X chromosome short tandem repeats (X-STRs) markers published in scientific journals searchable via PubMed. Furthermore, this database presents other relevant information concerning X-STRs, such as genetic and physical locations, allele structure, nomenclature, mutation rates, primers described in the literature and likelihood ratio calculation. The entire scientific community is now encouraged to submit their X-STR population genetic data to this website, available at http://www.bgbx.com.br. Regarding future prospects of BGBX, the authors intend to expand the website with data and information of X-linked insertion–deletion polymorphisms.     

Echinococcus granulosus antigen B structure: subunit composition and oligomeric states

Background

Antigen B (AgB) is the major protein secreted by the Echinococcus granulosus metacestode and is involved in key host-parasite interactions during infection. The full comprehension of AgB functions depends on the elucidation of several structural aspects that remain unknown, such as its subunit composition and oligomeric states.

Methodology/Principal Findings

The subunit composition of E. granulosus AgB oligomers from individual bovine and human cysts was assessed by mass spectrometry associated with electrophoretic analysis. AgB8/1, AgB8/2, AgB8/3 and AgB8/4 subunits were identified in all samples analyzed, and an AgB8/2 variant (AgB8/2v8) was found in one bovine sample. The exponentially modified protein abundance index (emPAI) was used to estimate the relative abundance of the AgB subunits, revealing that AgB8/1 subunit was relatively overrepresented in all samples. The abundance of AgB8/3 subunit varied between bovine and human cysts. The oligomeric states formed by E. granulosus AgB and recombinant subunits available, rAgB8/1, rAgB8/2 and rAgB8/3, were characterized by native PAGE, light scattering and microscopy. Recombinant subunits showed markedly distinct oligomerization behaviors, forming oligomers with a maximum size relation of rAgB8/3>rAgB8/2>rAgB8/1. Moreover, the oligomeric states formed by rAgB8/3 subunit were more similar to those observed for AgB purified from hydatid fluid. Pressure-induced dissociation experiments demonstrated that the molecular assemblies formed by the more aggregative subunits, rAgB8/2 and rAgB8/3, also display higher structural stability.

Conclusions/Significance

For the first time, AgB subunit composition was analyzed in samples from single hydatid cysts, revealing qualitative and quantitative differences between samples. We showed that AgB oligomers are formed by different subunits, which have distinct abundances and oligomerization properties. Overall, our findings have significantly contributed to increase the current knowledge on AgB expression and structure, highlighting issues that may help to understand the parasite adaptive response during chronic infection.     

Clinical and cytokine profile evaluation in Northeast Brazilian psoriasis plaque-type patients

Objective and Design

Psoriasis is a common, enigmatic, and recurrent disease. The precise etiology and pathogenesis of psoriasis are still unclear. Psoriasis has been treated as an inflammatory disorder related to an underlying Th1/Th17-dominated immune response. Interleukins are involved in the development of psoriasis lesions through Th-17-associated inflammation. Th1 and Th17 cytokines are found in skin lesions and in the peripheral blood of psoriasis patients.We sought to analyze serum levels of IL-1-β, IL-8, IL-9, IL-27, IL-29, IL-35, IFN-γ, TNF and TGF-β in patients with psoriasis and healthy control volunteers.

Material

Blood samples were collected from fifty-three patients with psoriasis and thirty-five healthy controls.

Methods

Serum cytokines concentrations were determined using an enzyme-linked immunosorbent assay.

Results

Serum IL-8, IL-9, IL-27, IL-29 and TNF levels were statistically significant in psoriasis patients. Detectable serum IL-9 levels were found in 47 patients of the 53 in the psoriasis group.

Conclusions

Interleukins-8, 27, 29 and TNF levels measured in the serum of psoriasis patients were slightly elevated as compared to healthy controls in a weakly significant way. On the other hand, there were highly significant differences in IL-9 levels between the two groups.

     

Recognition of 5-hydroxymethylcytosine by the Uhrf1 SRA domain

Recent discovery of 5-hydroxymethylcytosine (5hmC) in genomic DNA raises the question how this sixth base is recognized by cellular proteins. In contrast to the methyl-CpG binding domain (MBD) of MeCP2, we found that the SRA domain of Uhrf1, an essential factor in DNA maintenance methylation, binds 5hmC and 5-methylcytosine containing substrates with similar affinity. Based on the co-crystal structure, we performed molecular dynamics simulations of the SRA:DNA complex with the flipped cytosine base carrying either of these epigenetic modifications. Our data indicate that the SRA binding pocket can accommodate 5hmC and stabilizes the flipped base by hydrogen bond formation with the hydroxyl group.