Developmental plasticity of behavioral traits in the self-fertilizing fish Kryptolebias marmoratus : an integrative approach

The present project aims to investigate the developmental plasticity of
behavioral traits in the mangrove rivulus, Kryptolebias marmoratus, and the
role of epigenetics in the regulation of this plasticity. Rivulus is one of the
two self-fertilizing hermaphrodite vertebrate species presenting the unique
advantage to show high level of behavioral plasticity within isogenic
populations, i.e. with very low level of genetic diversity. Moreover, different
isogenic wild populations show distinct genotypes. This particularity allows
the precise identification of genetic and environmental sources of plasticity.
This project will be divided into two specific objectives. First, rivulus larvae
from two distinct lineages will be exposed for 60 days post- hatching (dph)
to low salinity (5ppt) or social stimuli (kin or non-kin contacts in dyads).
Personality traits (aggressiveness and boldness) will be assessed by videotracking
technologies at 150, 170 and 190 dph using the “model” and the
“open field locomotion” tests, respectively. This design will permit to
investigate the effects of environmental and social stimuli applied during
development, on aggressiveness and boldness later in adults. These
behavioral traits will be compared within each lineage to determine the
environmental contribution; between the two lineages to estimate the
genetic part of these personalities; between the exposed fish and their
parents to assess whether descendant’s behaviors differ from parent’s
behaviors due to environmental and social factors during embryogenic
development. Second, the role of biochemical and molecular mechanisms
underlying developmental behavioral plasticity in brain will be investigated.
The cellular phenotypic responses will be analyzed at the protein
expression level using an original workflow of quantitative label- and gelfree
proteomic approach. Simultaneously, we will analyze genome-wide
level of DNA methylation and hydroxymethylation in adult’s brain of two
experimental groups, by bisulfite and oxidative bisulfite sequencing,
respectively. Consequently, differentially methylated regions (DMRs) and
differentially hydroxymethylated regions (hydroxyDMRs) will be identified.
Afterwards, some identified DMRs and hydroxyDMRs will be selected for
extended analysis in all experimental groups and within both lineages using
pyrosequencing. These DMRs will also be selected according to proteomics
data and will be linked to the expression of genes of interest (RT qPCR).
Strongly linking information from the organismal and cellular phenotypes of
each rivulus’ lineage will permit a better understanding of the sequence of
molecular key events leading to behavioral modifications that permit the
organism to face with new situation. Comparing this phenotype anchoring
among lineages will help to deepen our knowledge about the role of
genotype variability on phenotypic flexibility. Moreover, this first long-term
study on imprinted behavioral plasticity and its possible epigenetic
regulation mechanisms of gene expression will open the research area of
transgenerational inheritance of a behavioral trait.