A cDNA,library from the skin of Kuna temporaria has been screened using a cDNA fragment probe that encodes the signal peptide of the precursor of esculentin from the skin secretion of Rana esculentu. With this approach, the cDNAs encoding the precursors of three peptides were isolated. Subsequently, the peptides predicted from the sequence of the cloned cDNAs as well as several structurally related peptides could be isolated from the skin secretion of R. temporuria. These peptides, which were named temporins, have a length of 10-13 residues and show some sequence similarity to hemolytic peptides Natural and synthetic temporins have antibacterial activity against gram-positive bacteria, but they are not hemolytic. Temporins are the smallest antibacterial peptides hitherto found in nature.
Gene-encoded peptide antibiotics are widespread in insects, plants and vertebrates and confer protection against bacterial and fungal infections. NF-κΒ is an important transcription factor for many immunity-related mammalian proteins and also for insect immune genes. The activity of NF-KB is regulated by the interaction with an inhibitor, ΙκΒ. It was recently demonstrated that glucocorticoids induce the synthesis of IKB in human cell lines. So far, all genes for peptide antibiotics have promoter motifs with NF-κΒ binding sites, but its actual function in peptide regulation has been studied only in insects. Here we show that glucocorticoid treatment of the frog Rana esculenta inhibits the transcription of all genes encoding antibacterial peptides by inducing the synthesis of ΙκΒα. These results suggest that also in vertebrates peptide-mediated innate immunity is controlled by NF-KB-regulated transcription.
Secretions of amphibian skin glands contain numerous antimicrobial peptides that play a crucial\ud
role in the defense against microorganisms. The location of these glands on the surface of the\ud
animal makes them a useful model for in vivo studies of the relationships between the innate\ud
immune system and the natural flora. Here, we present the results of a study showing that in\ud
Rana esculenta the total antimicrobial activity of skin secretion is modulated by the presence of\ud
the natural flora. Frogs kept in a sterile environment do not produce antimicrobial peptides. This\ud
finding represents the first in vivo demonstration of the induction of defense peptides in a\ud
vertebrate. We also present data on the morphological changes in skin glands of animals kept in\ud
sterile conditions or treated with glucocorticoids. Cells from glands regenerated under normal\ud
conditions, but not those from “sterile” frogs, contain κB-binding activity in the cytoplasm
The sequence of a gene from Bombina orientalis was determined which codes for antibacterial peptides. The gene comprises two exons separated by a large intron. Exon 1 codes for the signal peptide, while exon 2 contains the genetic information for two identical bombinins and one bombinin H. The promoter region of the bombinin gene contains putative recognition sites for nuclear factors, such as NFU UB and NF-IL6. In vivo experiments on B. orientalis have shown that a short contact with bacteria is sufficient to induce a marked increase in the amount of antibacterial peptides in the skin secretion of frogs. This increase was suppressed by pretreatment with glucocorticoids. In the latter case, a significant increase of IU UBK K in the secretion is also detectable.z 1998 Federation of European Biochemical Societies.
Plant pathogens negatively affect agricultural production by reducing the plant yield and worsening the nutritional and qualitative characteristics of the harvest. To limit the damage caused by pathogen infection, crops are treated with large doses of pesticides, which cause soil and groundwater pollution. The use of crop varieties genetically resistant to necrotrophs represents a more sustainable solution but is limited by the scarcity of resistance genes to be integrated into crops. For this reason, the identification of new
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.