Dimerization of aurein 1.2: Effects in structure, antimicrobial activity and aggregation of Cândida albicans cells

Antimicrobial peptides (AMPs) are a promising solution to face the antibiotic-resistant problem because they display little or no resistance effects. Dimeric analogues of select AMPs have shown pharmacotechnical advantages, making these molecules promising candidates for the development of novel antibiotic agents. Here, we evaluate the effects of dimerization on the structure and biological activity of the AMP aurein 1.2 (AU). AU and the C- and N-terminal dimers, (AU)2K and E(AU)2, respectively, were synthesized by solid-phase peptide synthesis. Circular dichroism spectra indicated that E(AU)2 has a coiled coil structure in water while (AU)2K has an α-helix structure. In contrast, AU displayed typical spectra for disordered structures. In LPC micelles, all peptides acquired a high amount of α-helix structure. Hemolytic and vesicle permeabilization assays showed that AU has a concentration dependence activity, while this effect was less pronounced for dimeric versions, suggesting that dimerization may change the mechanism of action of AU. Notably, the antimicrobial activity against bacteria and yeast decreased with dimerization. However, dimeric peptides promoted the aggregation of C. albicans. The ability to aggregate yeast cells makes dimeric versions of AU attractive candidates to inhibit the adhesion of C. albicans to biological targets and medical devices, preventing disease caused by this fungus. © 2013 Springer-Verlag Wien.

The correlation between electronic structure and antimalarial activity of alkoxylated and hydroxylated chalcones

Chalcones have shown potential to several pharmacological applications including antimalarial properties. We employed multivariate data analysis to correlate the antimalarial activity with electronic structure descriptors obtained through quantum mechanical calculations. The results show high statistical significance and bring valuable insights in order to design new compounds. © 2013 Springer Science+Business Media New York.

Structure and dynamics of the community of periphytic algae in a subtropical reservoir (state of São Paulo, Brazil)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Population, social equity and changing production patterns

Includes bibliography

Synthesis, X-ray crystal structure and theoretical calculations of antileishmanial neolignan analogues

A síntese e a estrutura cristalina por difração de raios-X de dois análogos de neolignanas, 2-(4-clorofenil)-1-feniletanona (20) e 2-[tio(4-clorofenil)]-1-(3,4-dimetoxifenil)propan-1-ona (12) são descritas. O composto 12 apresenta atividade intracelular contra Leishmania donovani e Leishmania amazonensis de amastigotas que causam a leishmaniose tegumentar e visceral. Além disso, a teoria do funcional de densidade (DFT) com o funcional híbrido B3LYP foi empregado para calcular um conjunto de descritores moleculares para dezenove análogos sintéticos de neolignanas com atividades antileishmaniose. Posteriormente, a análise discriminante stepwise foi realizada para investigar possíveis relações entre a estrutura molecular e atividades biológicas. Por meio dessa análise os compostos foram classificados em dois grupos ativos e inativos de acordo com seu grau de atividade biológica, e as propriedades mais importantes foram as cargas de alguns átomos, a afinidade eletrônica e o ClogP.

Is there post-meiotic transcriptional activity during hemipteran spermiogenesis?

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Long-range and short-range structures of cube-like shape SrTiO3 powders: microwave-assisted hydrothermal synthesis and photocatalytic activity

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Structure and secretion mechanisms of floral glands in Diplopterys pubipetala (Malpighiaceae), a neotropical species

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Geoffroy's side-necked turtle [Phrynops geoffroanus (Schweigger, 1812), Testudines: Chelidae] as a model for evolutionary ecotoxicology: relationship between environmental contamination, conditions and genetic variability

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Structure of the pelvic and penile urethra--relationship with the ducts of the sex accessory glands of the Mongolian gerbil (Meriones unguiculatus)

The urethra is the main place of entry for sexually transmitted pathogens. However, there is little literature on the morphology of the urogenital system, principally the urethra and ducts of the sex accessory glands. The Mongolian gerbil is an insectivorous, herbivorous and monogamous rodent with nocturnal habits; it has been used successfully as a laboratory animal since the 1960s. Therefore, the objective of the present paper was to describe the structure and ultrastructure of the urethra and its relations to the ducts of the accessory sex glands of the Mongolian gerbil (Meriones unguiculatus), contributing to the understanding of the reproductive biology of the rodent and aiming to provide data for future experimental studies. Conventional techniques of light and scanning electron microscopy were utilized. The urethra and ducts of the accessory sex glands are similar to those of the albino rat and the mouse. However, there is variation in drainage type among accessory sex glands for the inner urethra. The ducts of the seminal vesicle, the ductus deferens, drain their contents independently into the ampullary duct that opens in the urethra. The ducts of the prostate, coagulating and bulbourethral glands drain their contents independently into the urethra.

Quantitative end qualitative analysis of the electrical activity of rectus abdominis muscle portions

The purpose of this study was to investigate the electrical behavior pattern of the Rectus abdominis muscle by qualitative and quantitative analysis of the electromyographic signal obtained from its superior, medium and inferior portions during dynamic and static activities. Ten voluntaries (aged X = 17.8 years, SD = 1.6) athletic males were studied without history of muscle skeletal disfunction. For the quantitative analysis the RMS (Root Mean Square) values obtained in the electromyographic signal during the isometric exercises were normalized and expressed in maximum voluntary isometric contraction percentages. For the qualitative analysis of the dynamic activity the electromyographic signal was processed by full-wave rectification, linear envelope and normalization (amplitude and time), so that the resulting curve of the processed signal was submitted to descriptive graphic analysis. The results of the quantitative study show that there is not a statistically significant difference among the portions of the muscle. Qualitative analysis demonstrated two aspects: the presence of a common activation electric pattern in the portions of Rectus abdominis muscle and the absence of significant difference in the inclination angles in the electrical activity curve during the isotonic exercises.

Investigation of the relationship between the structure and function of Ts2, a neurotoxin from Tityus serrulatus venom

Scorpion toxins targeting voltage-gated sodium (NaV) channels are peptides that comprise 6076 amino acid residues cross-linked by four disulfide bridges. These toxins can be divided in two groups (a and beta toxins), according to their binding properties and mode of action. The scorpion a-toxin Ts2, previously described as a beta-toxin, was purified from the venom of Tityus serrulatus, the most dangerous Brazilian scorpion. In this study, seven mammalian NaV channel isoforms (rNaV1.2, rNaV1.3, rNaV1.4, hNaV1.5, mNaV1.6, rNaV1.7 and rNaV1.8) and one insect NaV channel isoform (DmNaV1) were used to investigate the subtype specificity and selectivity of Ts2. The electrophysiology assays showed that Ts2 inhibits rapid inactivation of NaV1.2, NaV1.3, NaV1.5, NaV1.6 and NaV1.7, but does not affect NaV1.4, NaV1.8 or DmNaV1. Interestingly, Ts2 significantly shifts the voltage dependence of activation of NaV1.3 channels. The 3D structure of this toxin was modeled based on the high sequence identity (72%) shared with Ts1, another T. serrulatus toxin. The overall fold of the Ts2 model consists of three beta-strands and one a-helix, and is arranged in a triangular shape forming a cysteine-stabilized a-helix/beta-sheet (CSa beta) motif.

Structure and antimycobacterial activity of the novel organometallic [Pd(C-bzan)(SCN)(dppp)] compound

The organometallic compound [Pd(C-bzan)(SCN)(dppp)] {bzan = N-benzylideneaniline, dppp = 1,3-bis(diphenylphosphino)propane} was synthesized and characterized by elemental analyses, infrared and H-1 and P-31(H-1) NMR spectroscopies. The crystal and molecular structures of the title complex were determined by single-crystal X-ray diffraction techniques. In vitro antimycobacterial evaluation demonstrated that the compound [Pd(C-bzan)(SCN)(dppp)] displayed a MIC of 5.15 mu M, which is superior than those values found for some commonly used anti-TB drugs and other Pd(II) complexes. (C) 2012 Elsevier B.V. All rights reserved.

Chromatin Structure of Ribosomal RNA Genes in Dipterans and Its Relationship to the Location of Nucleolar Organizers

Nucleoli, nuclear organelles in which ribosomal RNA is synthesized and processed, emerge from nucleolar organizers (NORs) located in distinct chromosomal regions. In polytene nuclei of dipterans, nucleoli of some species can be observed under light microscopy exhibiting distinctive morphology: Drosophila and chironomid species display well-formed nucleoli in contrast to the fragmented and dispersed nucleoli seen in sciarid flies. The available data show no apparent relationship between nucleolar morphology and location of NORs in Diptera. The regulation of rRNA transcription involves controlling both the transcription rate per gene as well as the proportion of rRNA genes adopting a proper chromatin structure for transcription, since active and inactive rRNA gene copies coexist in NORs. Transcription units organized in nucleosomes and those lacking canonical nucleosomes can be analyzed by the method termed psoralen gel retarding assay (PGRA), allowing inferences on the ratio of active to inactive rRNA gene copies. In this work, possible connections between chromosomal location of NORs and proportion of active rRNA genes were studied in Drosophila melanogaster, and in chironomid and sciarid species. The data suggested a link between location of NORs and proportion of active rRNA genes since the copy number showing nucleosomal organization predominates when NORs are located in the pericentric heterochromatin. The results presented in this work are in agreement with previous data on the chromatin structure of rRNA genes from distantly related eukaryotes, as assessed by the PGRA.