Drosophila antifungal defensin: Recombinant Expression, Evolution and Novel Functional Feature

Drosomycin is the first inducible antifungal peptide of 44 residues initially isolated from bacteria-challenged Drosophila melangaster, and is also the target gene of the Toll signal pathway. This unique antifungal peptide belongs to the cysteine-stabilized α-helical and β-sheet (CSαβ) structural superfamily whose members are composed of an α-helix and a three-stranded β-sheet. Such structural homologues are also recognized in two fungal genomes [1]. By using recombinant drosomycins expressed in E. coli [2], we extended functional spectra of drosomycin, which include anti-parasitic and anti-yeast activities [3]. Two evolutionary epitopes (named α- and γ-patch) and the m-loop have been proposed as putative functional regions of drosomycin for interaction with fungi and the parasite, respectively [3]. Similarity in sequence, structure and biological activity suggests that insect drosomycin and some related defensins from plants and fungi could originate from a common ancestor

Central mechanisms underlying the changes of leptin sensitivity in Brandt's voles

During the pregnancy, hypothalamic SOCS3 mRNA was significantly increased during mid and late pregnancy. Hypothalamic Ob-Rb mRNA showed a tendency of decrease during midpregnancy. These results indicated that the increase of SOCS3 and the decrease of Ob-Rb mRNA in the hypothalamus may be involved in the development of pregnancy-associated leptin resistance. During the pregnancy, there were no significant changes in hypothalamic NPY, AgRP and CART mRNA levels despite hyperleptinemia. However, hypothalamic POMC mRNA was significantly decreased during mid and late pregnancy. These results indicated that leptin failed to regulate hypothalamic neuropeptides due to leptin resistance in pregnant voles. Decreased hypothalamic POMC mRNA may be responsible for hyperphagia in pregnant voles.