B chromosomes and epigenetic modifications: how DNA methylation relates to environmental stress in Astatotilapia latifasciata

• Grant number: 22/02544-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2022
• End date: March 31, 2023
• Field of knowledge: Biological Sciences - Genetics - Animal Genetics
• Principal Investigator: César Martins
• Grantee: João Pedro Silva Climaco
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Associated research grant: 15/16661-1 - Sex and B chromosome enigmas: model systems for the study of chromosome and genome evolution, AP.TEM

Abstract

Despite the nature of the name "B chromosomes" descend from the idea of extra and dispensable elements of the genome, different from the so called "A chromosomes" and from aneuploidy cases (Beukeboom, 1994), its presence throughout most broad eukaryote clades and its heterogeneity in evolution and behavior amongst species prevent a unified conceptual definition (Camacho, 2005). As a matter of fact, recent discoveries suggest that these elements, being originated from A and sex chromosomes (Burt & Trivers, 2009), present a vast "repository" of genetic sequences that may affect different cell functions and biological processes in general (Ahmad & Martins, 2019). Considering the B chromosome's presence in the cichlid Astatotilapia latifasciata, affecting the expression of DNA sequences (Ramos et al., 2016) through mechanisms such as epigenetic modifications (Cardoso et al., 2019) and Transposable Elements expression (Coan & Martins, 2018), this species has been used as a model for origin, function and evolution of B and sex chromosomes. Additionally, the genus Astatotilapia, amongst other Haplochromini species, has been used in other researches as the means of studying rapid adaptive radiations of cichlid fishes in the East African Great Lakes (Kornfield & Smith, 2000), especially considering its ecological and genetic diversity (Kocher, 2004). Thus, given the impact of epigenetic regulation through DNA methylation on the global profile of gene expression amongst organisms (Cedar & Bergman, 2009), as well as the epigenetic role played by B chromosomes in A. latifasciata, the present research proposes the analysis of DNA methylation differences amongst B- and B+, male and female individuals of A. latifasciata in response to controlled environmental stress, as well as the probable epigenetic differences between these groups on candidate regions prior to the experiment.(AU)