The Significance of Hypervariability and Conserved Motifs in Antimicrobial Peptides from Tree Frogs.

Amphibians' skin is a rich source of natural antimicrobial peptides (AMPs). These AMPs exhibit marked inter- and intraspecific sequence divergence linked to the arms race between host and pathogens. Here, we combine peptidomics, molecular modeling, and phylogenetic analyses to understand the evolution of AMPs in Cophomantini, a diverse clade of neotropical tree frogs, and to investigate their interaction with bacterial membranes. Consistent with results in other amphibians, all species of Cophomantini secrete a mixture of peptides. We selected the hylin peptide family to survey sequence variability and the presence of common amino acid motifs. We found that most species secrete a unique set of hylins that, though variable, share the conserved motif Gly-X-X-X-Pro-Ala-X-X-Gly, with Gly and Pro colocalizing with charged or polar residues. Our modeling revealed that Pro curves the peptide through a hinge, facilitating its insertion into the bacterial membrane and, once inserted, contributes to stabilizing the pore structure. The phylogenetic inference using hylid prepro-peptides showed the need to classify new AMPs using the full-length sequence of the prepro-peptide region and highlighted the complex relationships between peptide families. Our findings revealed that conserved motifs occurred independently in distinct AMP families, suggesting a convergent evolution and a significant role in peptide-membrane interactions.

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.

Identification of New Ocellatin Antimicrobial Peptides by cDNA Precursor Cloning in the Frame of This Family of Intriguing Peptides.

Ocellatins are a family of antimicrobial peptides found exclusively in the Leptodactylus genus. To date, 10 species have been studied and more than 23 peptides described. Here we report the sequences of five new peptides from the skin of the frog Leptodactylus latrans (Anura: Leptodactylidae) determined by cDNA cloning of the complete prepro-peptide structures. The mature peptides were characterized with in silico tools and compared with those previously described. With 21 amino acid residues, this new set of peptides not previously described in the Leptodactylus genus share between 100 and 76.2% similarity to ocellatin antimicrobial peptides. These novel peptides are cationic and their three-dimensional (3D) structure holds the highly conserved residues G1, D4, K7, and K11 and a high theoretical amphipathic α-helix content. Furthermore, in silico analyses of these new peptides predicted antimicrobial activity. This study is framed in the context of previous work published about ocellatins, and therefore, provides a review of this intriguing family of peptides.

Efectos de un taller integral en desarrollo de la creatividad para la producción de material didáctico sobre lecto-escritura, de las futuras profesoras de educación primaria del Instituto Superior Pedagógico Particular Encinas de Lima

La investigación tuvo como objetivo determinar los efectos del taller en el desarrollo de la creatividad en la producción de material didáctico para la Lecto-escritura, es un grupo de futuras profesoras de Educación Primaria, para lo cual se diseñó y aplicó el Taller Integral con la finalidad de desarrollar contenidos y habilidades relacionadas con las categorías formativo, informativo y original. La fundamentación teórica del estudio corresponde a la teoría de Guilford sobre pensamiento convergente y divergente; a la de Mc Kinnon sobre el proceso creativo y a la de Mihalyi sobre el producto creativo. Tanto el grupo experimental, como el grupo control, fueron evaluados antes y después de aplicar el Taller Integral y los resultados demostraron que el grupo experimental en la medición post-test incrementó significativamente su promedio en comparación con el grupo control; quedando así demostrada la efectividad del mencionado taller. Se sugiere utilizar el Taller Integral para desarrollar la creatividad del futuro profesor en la elaboración de material didáctico para otros temas de aprendizaje. Palabras claves: Creatividad en material didáctico. Producción de materail creativo. Lecto-escritura. Creatividad. Taller de Creatividad.