Investigating somatic hypermutation in the delta/gamma TCR chains in Trichechus manatus latirostris (Florida manatee)

• Grant number: 19/03568-4
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Effective date (Start): March 31, 2019
• Effective date (End): September 29, 2019
• Field of knowledge: Biological Sciences - Genetics - Animal Genetics
• Principal Investigator: Mariana Freitas Nery
• Grantee: Bruna Cristina Dias
• Supervisor: Michael Frederick Criscitiello
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Research place: Texas A&M University, United States
• Associated to the scholarship: 17/14831-2 - Molecular evolution of immune system genes in aquatic mammals: identifying molecular footprints of the colonization of new environment, BP.MS

Abstract

Manatees (Order Sirenia) are susceptible to various threats to their populations. Naturalthreats to the Florida manatee include cold water temperatures, hurricanes, harmful algal blooms, and the spread of diseases and pathogens. Based on clinical findings, Florida manatees are naturally resistant to infectious and natural diseases, which may result from a highly developed and efficient immune system. Their apparent disease resistance certifies a further comprehension of their immunological adaptations to marine and freshwater environment. However, immune studies in manatees are still scarce, and they usually focus on correlations with cold stress syndrome and red tide exposure. The somatic hypermutation process is a type of genetic alteration in the immune system known to happen in the immunoglobulins heavy- and light- chains. During this process, point mutations are introduced in the variable region gene segments of immunoglobulins resulting in a change in the expressed protein, altering the affinity of specificity for antigen. It is believed that the T cell receptor (TcR) loci do not undergo somatic hypermutation, although recent studies indicate the presence of that process to be happening in the delta, gamma and alpha chain of the sandbar shark, the nurse shark and the dromedary camel. Moreover, besides the traditional belief that manatees have an efficient immune system, manatees have low V(D)J combinatorial diversity and few constant region isotypes on their immunoglobulin heavy chain (IgH), besides lacking the clan III V segments, meaning that manatees have limited IGHV clan and combinatorial diversity. Thus, this project aims to investigate the presence of the somatic hypermutation process in the delta and gamma TcR chains of the Florida manatee, possibly mitigating the lack of diversity observed in the immunoglobulin heavy chain. (AU)