Over the last weeks, the O. nasuta fish have been reproducing several times. After egg laying, the females pick up the eggs in their mouth until the juvenile fish are big enough to survive. The left picture shows the open mouth of a female with three yellow eggs visible, the right picture shows very young juveniles still feeding on the yolk of the egg.
One of the major aims of the GENBAS project is to investigate which genes are triggered in the female brain during the mating process and when she is confronted with a male from the same species or with a male from a different species. Genes that are differentially expressed may have been an important trigger for the speciation process.
We have tested the applicability of the Quantseq 3′ kit, a relatively new RNAseq approach that allows quantification of gene expression in 96 samples at once. We analysed gene expression in six brainparts (CE: cerebellum, OB: olfactory bulbs, OT: optic tectum, TE: telencephalon, DI: diencephalon, BS: brain stem) of five O. nasuta and O. ventralis females that have never been exposed to males. The (dis)similarities in gene expression between samples can be visualised through a PCA plot. As shown in the figure below, samples from the two species clustered according to brain part. This suggests that under the control conditions, both species are experiencing their environment in a very similar way.