Please join us for the Master of Science thesis defense of Daniela Losada in Molecular and Macromolecular Sciences.  

TITLE OF THESIS: "Identification, tissue characterization and innate immune role of Angiogenin-4 expression in young broiler chickens”

ABSTRACT: Intestinal epithelial cells are major producers of antimicrobial proteins, which play an important role in innate immunity. Ribonuclease A superfamily members are a class of important antimicrobial proteins that are involved in host-defense mechanisms in vertebrates. Angiogenin-4 (Ang4), a member of this RNase superfamily, has been demonstrated to be secreted by Paneth and goblet cells in mice. This thesis shows the successful cloning and characterization of the Ang4 gene in chickens, referred to as chicken (ch) Ang4. Ang4 was found for the first time in a non-mammalian species and chAng4 mRNA expression was detected in chicken intestinal epithelial and lymphoid cells. Characterization of chAng4 revealed 99% nucleotide and 97% amino acid sequence homology to mouse (m) Ang4. The similarities in putative functional regions with mAng4 suggest a role of chAng4 in innate immunity and in the regulation of gut microbiota. Furthermore, the mRNA expression pattern of chAng4 was studied in broilers in the presence and absence of beneficial bacteria (probiotics) and organic acids. The results showed that the highest level of chAng4 mRNA expression occurred in the bursa of Fabricius of one-day-old chickens. At the age of 1 day, chAng4 mRNA expression was already observed in crop, proventriculus, duodenum, jejunum, ileum and cecal tonsils. Broilers that were supplemented with probiotics and organic acids for only 7 days showed higher levels of chAng4 expression in crop, proventriculus and jejunum, when compared with those supplemented for 14 days. In addition, chickens that were not treated with probiotics and organic acids had a constant high level of expression of chAng4 mRNA in cecal tonsils and bursa throughout the study. chAng4 mRNA expression was associated with naturally occurring (non-supplemented) bacteria and with supplemented (probiotic) bacteria in chicken drinking water. In conclusion, we were able to identify and characterize a new antimicrobial gene (chAng4) throughout the gastrointestinal tract of chickens. The encoded chAng4 protein is thought to have a potential bactericidal effect against intestinal non-pathogenic and pathogenic microbes, hence modulating the intestinal microbiota and the innate immune system of chickens. chAng4 may help minimize the use of antibiotics in poultry feed.

Anyone who wishes to attend the public presentation should contact the Graduate Studies Coordinator at gsc@upei.ca to receive the link to the meeting.