Characterization of a thermotolerant laccase produced by Streptomyces sp. SB086

Laccases have become desirable enzymes for application in many industrial processes. Nowadays, most of these enzymes are obtained from fungi. Among prospective studies for bacterial laccase genes, some have included actinomycetes, but only a few studies have characterized the enzyme produced. Thus, we have isolated a laccase-producing actinomycete from forest soil under restoration process and further aimed to characterize its produced enzyme. The isolate SB086 was assigned to the Streptomyces genus by a combination of phenotypical, chemical and phylogenetic properties. Our data indicate that the bacterium produces a thermotolerant laccase. The maximum activity was obtained in the pH range 4.0–5.0 and at 50 °C in reaction mixture containing 5 mM CuSO₄; thermal stability was noted at 60 °C and 70 °C—a well-desired characteristic for industry. The active enzyme presented a high molecular mass (over 100 kDa) and was less sensitive to inhibition by metal ions than generally described for bacterial laccases. Our findings support in silico data of bacterial laccase secretion, and reinforce the view that actinomycetes may be a rich source of laccase for industrial application.     

Both α1- and α2-adrenoceptors in the Insular Cortex Are Involved in the Cardiovascular Responses to Acute Restraint Stress in Rats

The insular cortex (IC) is a limbic structure involved in cardiovascular responses observed during aversive threats. However, the specific neurotransmitter mediating IC control of cardiovascular adjustments to stress is yet unknown. Therefore, in the present study we investigated the role of local IC adrenoceptors in the cardiovascular responses elicited by acute restraint stress in rats. Bilateral microinjection of different doses (0.3, 5, 10 and 15 nmol/100 nl) of the selective α₁-adrenoceptor antagonist WB4101 into the IC reduced both the arterial pressure and heart rate increases elicited by restraint stress. However, local IC treatment with different doses (0.3, 5, 10 and 15 nmol/100 nl) of the selective α₂-adrenoceptor antagonist RX821002 reduced restraint-evoked tachycardia without affecting the pressor response. The present findings are the first direct evidence showing the involvement of IC adrenoceptors in cardiovascular adjustments observed during aversive threats. Our findings indicate that IC noradrenergic neurotransmission acting through activation of both α₁- and α₂-adrenoceptors has a facilitatory influence on pressor response to acute restraint stress. Moreover, IC α₁-adrenoceptors also play a facilitatory role on restraint-evoked tachycardiac response.     

Procedures to characterize and study P2Z/P2X7 purinoceptor: flow cytometry as a promising practical, reliable tool

The expression of P2Z/P2X7 purinoceptor in different cell types is well established. This receptor is a member of the ionotropic P2X receptor family, which is composed by seven cloned receptor subtypes (P2X1 - P2X7). Interestingly, the P2Z/P2X7 has a unique feature of being linked to a non-selective pore which allows the passage of molecules up to 900 Da depending on the cell type. Early studies of P2Z/P2X7 purinoceptor were exclusively based on classical pharmacological studies but the recent tools of molecular biology have enriched the analysis of the receptor expression. The majority of assays and techniques chosen so far to study the expression of P2Z/P2X7 receptor explore directly or indirectly the effects of the opening of P2Z/P2X7 linked pore. In this review we describe the main techniques used to study the expression and functionality of P2Z/P2X7 receptor. Additionally, the increasing need and importance of a multifunctional analysis of P2Z/P2X7 expression based on flow cytometry technology is discussed, as well as the adoption of a more complete analysis of P2Z/P2X7 expression involving different techniques.     

Inferring a weighted elastic network from partial unfolding with coarse‐grained simulations

A number of studies have demonstrated that simple elastic network models can reproduce experimental B‐factors, providing insights into the structure–function properties of proteins. Here, we report a study on how to improve an elastic network model and explore its performance by predicting the experimental B‐factors. Elastic network models are built on the experimental coordinates, and they only take the pairs of atoms within a given cutoff distance r_c into account. These models describe the interactions by elastic springs with the same force constant. We have developed a method based on numerical simulations with a simple coarse‐grained force field, to attribute weights to these spring constants. This method considers the time that two atoms remain connected in the network during partial unfolding, establishing a means of measuring the strength of each link. We examined two different coarse‐grained force fields and explored the computation of these weights by unfolding the native structures. Proteins 2014; 82:119–129. © 2013 Wiley Periodicals, Inc.     

Immunoblotting of soluble antigens in Paracoccidioides brasiliensis culture

This study investigated the major soluble antigens produced by Paracoccidioides brasiliensis (Pb339) cultured in solid Sabouraud (pH 5.6 and 8.5), Sabouraud plus brain heart infusion and liquid tomato juice‐enriched complex medium media at intervals of 3 days over 30 days by immunoblotting and concluded that, to optimize the source of each antigen, both time and growth conditions should be considered.     

Molecular phylogeny of the Western Palaearctic Cordulegaster taxa (Odonata: Anisoptera: Cordulegastridae)

Although Odonata are a key component of many freshwater ecosystems, their taxonomy and evolutionary history is still far from being well resolved. In the present study, we report the first molecular phylogeny for the Western Palaearctic Cordulegaster genus (Odonata: Anisoptera: Cordulegastridae). We sequenced fragments of both mitochondrial and nuclear genes [cytochrome c oxidase I (COI) and Internal Transcribed Spacer‐1 (ITS‐1)] from eight species and 13 subspecies, from western, southern and central Europe, Turkey, and Morocco. Our data support the existence of two major groups corresponding to the traditional boltonii‐ and bidentata‐groups. Both groups are monophyletic based on COI sequences and the distinctiveness of Cordulegaster princeps, Cordulegaster trinacriae, Cordulegaster picta and Cordulegaster heros relative to Cordulegaster boltonii, and Cordulegaster helladica and Cordulegaster insignis relative to Cordulegaster bidentata, is confirmed. All species are also monophyletic for ITS‐1, with the exception of Cordulegaster helladica buchholzi, which shares the haplotype with C. insignis. Although moderate levels of genetic diversity were found within C. boltonii, there was no clear separation among the four subspecies, with the exception of the populations of Cordulegaster boltonii algirica from North Africa. Similarly, no genetic differentiation was found between the two subspecies of C. bidentata, Cordulegaster bidentata bidentata and Cordulegaster bidenta sicilica. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111, 49–57.     

Senescence and steroid hormone receptor reactivities in accessory sex glands of elderly rats (Sprague-Dawley) following exogenous hormonal therapy

The aim of this study was to characterize the stromal and epithelial distribution of AR, ERα and ERβ reactivities in the different accessory sex glands of elderly rats and during strong hormonal changes. Ten month old male rats were divided into six senile groups and submitted to treatment: Senile/Control group (SC); Senile/Testosterone group (ST): Senile/Estrogen group (SE); Castrated group (CA); Castrated/Testosterone group (CT); Castrated/Estrogen group (CE). After a 30-day treatment, the prostatic ventral lobe (VL), dorsal lobe (DL) and coagulating gland (CG) samples were processed for immunohistochemistry and Western Blotting. The results showed that AR immunoreactivity was characterized in the epithelium of VL and DL in senile/control rats and senile rats submitted to exogenous hormonal therapy. AR reactivity in the coagulating gland was verified predominantly in the stromal cells in the different experimental groups. ERα reactivity occurred predominantly in the stromal compartment in all accessory sex glands. In the DL and CG, ERα immunoreactivities were intense in the groups which received testosterone (ST) and estrogen (SE). ERβ immunoreactivity in the CG was verified in the stromal compartment in the different experimental groups, showing a positive response to both increased testosterone and estrogen levels. ERβ reactivity, in the DL, was intensified in the stroma of senile rats with higher serum testosterone levels, and in senile rats with increased serum estrogen levels, especially in the glandular epithelium. Thus, the results revealed different distribution pattern of steroid hormone receptors in each one of the prostatic lobes in senescence, especially in the prostate dorsal lobe and coagulating gland, which is a fundamental factor due to the fact that major prostatic diseases occur in a later period of life.     

Medial prefrontal cortex endocannabinoid system modulates baroreflex activity through CB(1) receptors

Neural reflex mechanisms, such as the baroreflex, are involved in the regulation of cardiovascular system activity. Previous results from our group (Resstel LB, Correa FM. Medial prefrontal cortex NMDA receptors and nitric oxide modulate the parasympathetic component of the baroreflex. Eur J Neurosci 23: 481-488, 2006) have shown that glutamatergic synapses in the ventral portion of the medial prefrontal cortex (vMPFC) modulate baroreflex activity. Moreover, glutamatergic neurotransmission in the vMPFC can be modulated by the endocannabinoids system (eCBs), particularly the endocannabinoid anandamide, through presynaptic CB(1) receptor activation. Therefore, in the present study, we investigated eCBs receptors that are present in the vMPFC, and more specifically whether CB(1) receptors modulate baroreflex activity. We found that bilateral microinjection of the CB(1) receptor antagonist AM251 (100 or 300 pmol/200 nl) into the vMPFC increased baroreflex activity in unanesthetized rats. Moreover, bilateral microinjection of either the anandamide transporter inhibitor AM404 (100 pmol/200 nl) or the inhibitor of the enzyme fatty acid amide hydrolase that degrades anandamide, URB597 (100 pmol/200 nl), into the MPFC decreased baroreflex activity. Finally, pretreatment of the vMPFC with an ineffective dose of AM251 (10 pmol/200 nl) was able to block baroreflex effects of both AM404 and URB597. Taken together, our results support the view that the eCBs in the vMPFC is involved in the modulation of baroreflex activity through the activation of CB(1) receptors, which modulate local glutamate release.     

Haplotypes of single cancer driver genes and their local ancestry in a highly admixed long-lived population of Northeast Brazil

Admixed populations have not been examined in detail in cancer genetic studies. Here, we inferred the local ancestry of cancer-associated single nucleotide polymorphisms (SNPs) and haplotypes of a highly admixed Brazilian population. SNP array was used to genotype 73 unrelated individuals aged 80-102 years. Local ancestry inference was performed by merging genotyped regions with phase three data from the 1000 Genomes Project Consortium using RFmix. The average ancestry tract length was 9.12-81.71 megabases. Strong linkage disequilibrium was detected in 48 haplotypes containing 35 SNPs in 10 cancer driver genes. All together, 19 risk and eight protective alleles were identified in 23 out of 48 haplotypes. Homozygous individuals were mainly of European ancestry, whereas heterozygotes had at least one Native American and one African ancestry tract. Native-American ancestry for homozygous individuals with risk alleles for HNF1B, CDH1, and BRCA1 was inferred for the first time. Results indicated that analysis of SNP polymorphism in the present admixed population has a high potential to identify new ancestry-associated alleles and haplotypes that modify cancer susceptibility differentially in distinct human populations. Future case-control studies with populations with a complex history of admixture could help elucidate ancestry-associated biological differences in cancer incidence and therapeutic outcomes.