Structure and function of cationic hylin bioactive peptides from the tree frog Boana pulchella in interaction with lipid membranes.

Amphibians have a great diversity of bioactive peptides in their skin. The cDNA prepro-peptide sequencing allowed the identification of five novel mature peptides expressed in the skin of Boana pulchella, four with similar sequences to hylin peptides having a cationic amphipathic-helical structure. Whole mature peptides and some of their fragments were chemically-synthesized and tested against Gram-positive and Gram-negative bacterial strains. The mature peptide hylin-Pul3 was the most active, with a MIC= 14 µM against Staphylococcus aureus. Circular dichroism assays indicated that peptides are mostly unstructured in buffer solutions. Still, adding large unilamellar vesicles composed of dimyristoyl phosphatidylcholine and dimyristoylphosphatidylglycerol increased the α-helix content of novel hylins. These results demonstrate the strong influence of the environment on peptide conformation and highlight its significance while addressing the pharmacology of peptides and their biological function in frogs.

Somuncurins: Bioactive Peptides from the Skin of the Endangered Endemic Patagonian Frog Pleurodema somuncurense.

The skin glands of amphibian species hold a major component of their innate immunity, namely a unique set of antimicrobial peptides (AMPs). Although most of them have common characteristics, differences in AMP sequences allow a huge repertoire of biological activity with varying degrees of efficacy. We present the first study of the AMPs from Pleurodema somuncurence (Anura: Leptodactylidae: Leiuperinae). Among the 11 identified mature peptides, three presented antimicrobial activity. Somuncurin-1 (FIIWPLRYRK), somuncurin-2 (FILKRSYPQYY), and thaulin-3 (NLVGSLLGGILKK) inhibited Escherichia coli growth. Somuncurin-1 also showed antimicrobial activity against Staphylococcus aureus. Biophysical membrane model studies revealed that this peptide had a greater permeation effect in prokaryotic-like membranes and capacity to restructure liposomes, suggesting fusogenic activity, which could lead to cell aggregation and disruption of cell morphology. This study contributes to the characterization of peptides with new sequences to enrich the databases for the design of therapeutic agents. Furthermore, it highlights the importance of investing in nature conservation and the power of genetic description as a strategy to identify new compounds.

Obesity, genomic ancestry, and socioeconomic variables in Latin American mestizos.

OBJECTIVES: This article aims to assess the contribution of genomic ancestry and socioeconomic status to obesity in a sample of admixed Latin Americans. METHODS: The study comprised 6776 adult volunteers from Brazil, Chile, Colombia, Mexico, and Peru. Each volunteer completed a questionnaire about socioeconomic variables. Anthropometric variables such as weight, height, waist, and hip circumference were measured to calculate body indices: body mass index, waist-to-hip ratio and waist-to-height ratio (WHtR). Genetic data were extracted from blood samples, and ancestry was estimated using chip genotypes. Multiple linear regression was used to evaluate the relationship between the indices and ancestry, educational level, and economic well-being. The body indices were dichotomized to obesity indices by using appropriate thresholds. Odds ratios were calculated for each obesity index. RESULTS: The sample showed high percentages of obesity by all measurements. However, indices did not overlap consistently when classifying obesity. WHtR resulted in the highest prevalence of obesity. Overall, women with low education level and men with high economic wellness were more likely to be obese. American ancestry was statistically associated with obesity indices, although to a lesser extent than socioeconomic variables. CONCLUSIONS: The proportion of obesity was heavily dependent on the index and the population. Genomic ancestry has a significant influence on the anthropometric measurements, especially on central adiposity. As a whole, we detected a large interpopulation variation that suggests that better approaches to overweight and obesity phenotypes are needed in order to obtain more precise reference values.

Thaulin-1: The first antimicrobial peptide isolated from the skin of a Patagonian frog Pleurodema thaul (Anura: Leptodactylidae: Leiuperinae) with activity against Escherichia coli.

Patagonia's biodiversity has been explored from many points of view, however, skin secretions of native amphibians have not been evaluated for antimicrobial peptide research until now. In this sense, Pleurodema thaul is the first amphibian specie to be studied from this large region of South America. Analysis of cDNA-encoding peptide in skin samples allowed identification of four new antimicrobial peptides. The predicted mature peptides were synthesized and all of them showed weak or null antimicrobial activity against Klebsiella pneumoniae, Staphylococcus aureus and Escherichia coli with the exception of thaulin-1, a cationic 26-residue linear, amphipathic, Gly- and Leu-rich peptide with moderate antimicrobial activity against E. coli (MIC of 24.7µM). AFM and SPR studies suggested a preferential interaction between these peptides and bacterial membranes. Cytotoxicity assays showed that thaulin peptides had minimal effects at MIC concentrations towards human and animal cells. These are the first peptides described for amphibians of the Pleurodema genus. These findings highlight the potential of the Patagonian region's unexplored biodiversity as a source for new molecule discovery.

Human papillomavirus DNA detection and typing in male urine samples from a high-risk population from Argentina.

The aim of the present study was to evaluate the first void urine (FVU) as a non-invasive sampling method for HPV detection and genotyping in a high-risk population. Men presenting with HPV associated penile lesions or HPV positive partners attending a urological department in La Plata, Argentina were enrolled for HPV detection and genotyping. DNA from 185 first-void urine samples was evaluated for the presence of HPV by nested polymerase chain reaction using MY09/11 and GP05/06 primers. The viral genotype was analyzed by means of the single-stranded conformation polymorphisms (SSCP) method. Seventy-three percent (135/185) of the FVU specimens were positive for HPV-DNA. The viral prevalence in patients with HPV-DNA positive partners was 68.8% (77/112), and 79.5% (58/73) of patients with penile lesions were found to be HPV positive. The most frequent viral type was HPV-11 (26.7%), followed by HPV-6 (23%), HPV-16 (21.5%), HPV-18 (6%), and HPV-31 (4.4%). In this study, 11.1% (15/135) of the HPV positive specimens were double infections. These results indicate that high-risk HPVs can be found in clinical lesions in a high percentage (43.8%), as simple or double infections. In this sense, the male population represents an important reservoir for the virus and may play a role in the transmission and perpetuation of the infection in the general population. The method described below provides a tool for detection and typing of HPV-DNA using samples obtained by non-invasive techniques and thus easy to obtain.