Identification and expression of a novel marsupial cathelicidin from the tammar wallaby (Macropus eugenii)

Abstract

Cathelicidins are important components of the innate immune system and have been identified in skin and epithelia of a range of mammals. In this study molecular techniques, including RACE-PCR, were used to identify the full cDNA sequence of a cathelicidin gene, MaeuCath8, from the Australian marsupial, the tammar wallaby, Macropus eugenii. This cathelicidin was not homologous to other such genes previously isolated from a tammar wallaby mammary gland EST library, however, it did contain 4 conserved cysteine residues which characterise the pre-propeptide and had 80% identity with a previously isolated bandicoot cathelicidin. Reverse transcriptase-PCR established the expression profile of MaeuCath8 in a range of tissues, including spleen, thymus, gastrointestinal tract, skin and liver, of the tammar wallaby from birth to adulthood. Expression of MaeuCath8 was observed in spleen and gastrointestinal tract of newborn animals and was observed in most tissues by 7 days post-partum. The results indicate that pouch young could synthesize their own antimicrobial peptides from an early age suggesting that this ability most likely plays a role in protecting the pouch young from infection prior to the development of immunocompetence.

The development of the immune tissues in marsupial pouch young

“…Early studies on some innate mechanisms, including the composition of the blood of pouch young (Block, 1964;Yadav, 1972;Basden, 1996), the composition of the commensal flora of the gut (Lentle, 2006;Chhour et al, 2010), expression of HLA-DR in the skin of newborn opossums (Coutinho et al, 1995) and the expression of antimicrobial peptides (Carman et al, 2008(Carman et al, , 2009Daly et al, 2008) has laid the foundation for our current understanding of the development of innate immune protection in pouch young marsupials. Further, research on the timing of the development of the innate immune system and early immune protection in marsupials is required.…”

“…Carman et al () identified a novel cathelicidin (MaeuCath8) in the tammar wallaby. Expression of this antimicrobial peptide was examined from birth to adulthood.…”

“…The expression of antimicrobial peptides in the skin of developing pouch young has been examined in the tammar wallaby (Carman et al, 2008(Carman et al, , 2009Daly et al, 2008;Wang et al, 2011). Antimicrobial peptides, including a class of molecules known as cathelicidins are an important part of the innate immune system of mammals (Scott and Hancock, 2000).…”

“…The expression of MaeuCath1 during pouch life is also suggested to be a critical nonspecific protection mechanism. Carman et al (2009) identified a novel cathelicidin (MaeuCath8) in the tammar wallaby. Expression of this antimicrobial peptide was examined from birth to adulthood.…”

Physical Mapping of Innate Immune Genes, Mucins and Lysozymes, and Other Non-Mucin Proteins in the Tammar Wallaby <i>(Macropus eugenii)</i>

“…Determining how these altricial young are immunologically protected is of great interest, which has led to studies of the maternal contribution to both pre-and postnatal protection through such mechanisms as maternal milk Demmer, 1999, 2000;Joss et al, 2007Joss et al, , 2009 and pouch secretions [Ambatipudi et al, 2007[Ambatipudi et al, , 2008. Most recently there has been an especial focus on the innate immune system, including a number of antimicrobial peptides -primarily cathelicidins [Carman et al, 2008[Carman et al, , 2009Daly et al, 2008].…”