Two new species of Daidalotarsonemus (Acari: Prostigmata: Tarsonemidae) from Brazil

International audienceTwo new tarsonemid species, Daidalotarsonemus esalqi sp. n. and Daidalotarsonemus savanicus sp. n., found on both native and crop plants in Brazil are described herein, based on adult females. Biological aspects of these species are briefly discussed. Individuals of Daidalotarsonemus savanicus sp. n. have been misidentified as Daidalotarsonemus tessellatus De Leon in previous reports of this species from Brazil. A key is provided to distinguish females of the Daidalotarsonemus species known to occur in Brazil

An acidic model pro-peptide affects the secondary structure, membrane interactions and antimicrobial activity of a crotalicidin fragment

In order to study how acidic pro-peptides inhibit the antimicrobial activity of antimicrobial peptides, we introduce a simple model system, consisting of a 19 amino-acid long antimicrobial peptide, and an N-terminally attached, 10 amino-acid long acidic model pro-peptide. The antimicrobial peptide is a fragment of the crotalicidin peptide, a member of the cathelidin family, from rattlesnake venom. The model pro-peptide is a deca (glutamic acid). Attachment of the model pro-peptide only leads to a moderately large reduction in the binding to- and induced leakage of model liposomes, while the antimicrobial activity of the crotalicidin fragment is completely inhibited by attaching the model pro-peptide. Attaching the pro-peptide induces a conformational change to a more helical conformation, while there are no signs of intra- or intermolecular peptide complexation. We conclude that inhibition of antimicrobial activity by the model pro-peptide might be related to a conformational change induced by the pro-peptide domain, and that additional effects beyond induced changes in membrane activity must also be involved.</p