title: Identification and functional characterization of a novel monotreme- specific antibacterial protein expressed during lactation.
abstract: Monotremes are the only oviparous mammals and exhibit a fascinating combination of reptilian and mammalian characters. They represent a component of synapsidal reproduction by laying shelled eggs which are incubated outside the mother's body. This is accompanied by a prototherian lactation process, marking them as representatives of early mammals. The only extant monotremes are the platypus, and the short- and long- beaked echidnas, and their distributions are limited to Australia and New Guinea. Apart for a short weaning period, milk is the sole source of nutrition and protection for the hatchlings which are altricial and immunologically naive. The duration of lactation in these mammals is prolonged relative to the gestational length and period of incubation of eggs. Much of the development of monotreme young occurs in the non-sterile ex-utero environment. Therefore the role of milk in the growth, development and disease protection of the young is of significant interest. By sequencing the cDNA of cells harvested from monotreme milk, we have identified a novel monotreme- specific transcript, and the corresponding gene was designated as the EchAMP. The expression profile of this gene in various tissues revealed that it is highly expressed in milk cells. The peptides corresponding to the EchAMP protein have been identified in a sample of echidna milk In silico analysis indicated putative antimicrobial potential for the cognate protein of EchAMP. This was further confirmed by in vitro assays using a host of bacteria. Interestingly, EchAMP did not display any activity against a commensal gut floral species. These results support the hypothesis of enhancement of survival of the young by antimicrobial bioactives of mammary gland origin and thus emphasize the protective, non- nutritional role of milk in mammals.
authors: Centre for Chemistry and Biotechnology, Deakin University, Geelong, Victoria, Australia. swathib@ccmb.res.in
authors: Swathi
authors: S
authors: Bisana
authors: Satish
authors: S
authors: Kumar
authors: Peggy
authors: P
authors: Rismiller
authors: Stewart C
authors: SC
authors: Nicol
authors: Christophe
authors: C
authors: Lefèvre
authors: Kevin R
authors: KR
authors: Nicholas
authors: Julie A
authors: JA
authors: Sharp
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism* / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D019295:Computational Biology; D017077:Culture Media, Conditioned / Q000737:chemistry; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D016678:Genome / Q000235:genetics; D006031:Glycosylation / Q000187:drug effects; D057809:HEK293 Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions / Q000187:drug effects; D007774:Lactation / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D008826:Microbial Sensitivity Tests; D008892:Milk / Q000737:chemistry; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D021382:Protein Sorting Signals; D017433:Protein Structure, Secondary; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013045:Species Specificity; D004442:Tachyglossidae / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
chemical_list: D023181:Antimicrobial Cationic Peptides; D017077:Culture Media, Conditioned; D021382:Protein Sorting Signals; D012333:RNA, Messenger