Gene expression profiling suggests differences in molecular mechanisms of fin elongation between cichlid species

Abstract

Comparative analyses of gene regulation inform about the molecular basis of phenotypic trait evolution. Here, we address a fin shape phenotype that evolved multiple times independently across teleost fish, including several species within the family Cichlidae. In a previous study, we proposed a gene regulatory network (GRN) involved in the formation and regeneration of conspicuous filamentous elongations adorning the unpaired fins of the Neolamprologus brichardi . Here, we tested the members of this network in the blockhead cichlid, Steatocranus casuarius , which displays conspicuously elongated dorsal and moderately elongated anal fins. Our study provided evidence for differences in the anatomy of fin elongation and suggested gene regulatory divergence between the two cichlid species. Only a subset of the 20 genes tested in S. casuarius showed the qPCR expression patterns predicted from the GRN identified in N. brichardi , and several of the gene-by-gene expression correlations differed between the two cichlid species. In comparison to N. brichardi , gene expression patterns in S. casuarius were in better (but not full) agreement with gene regulatory interactions inferred in zebrafish. Within S. casuarius , the dorsoventral asymmetry in ornament expression was accompanied by differences in gene expression patterns, including potential regulatory differentiation, between the anal and dorsal fin.

Molecular mechanisms underlying nuchal hump formation in dolphin cichlid, Cyrtocara moorii

“…The top 7 genes with lowest CV were chosen as candidate reference genes for qPCR expression analysis. None of the candidate have been identified as suitable reference genes in previous studies of East African cichlids, indicating the importance of identification of suitable reference genes for each experimental setup 30–34,36–38 . The results of reference gene rankings by geNorm and NormFinder software suggested rnf123 and cnnm3 as top two most stable reference genes (Table 3).…”

The Bgee suite: integrated curated expression atlas and comparative transcriptomics in animals

“…Comparative transcriptomics is essential to understand the molecular basis for phenotypes, such as, for instance, evolution of animal morphology ( 70 ), embryonic cell differentiation ( 71 ), species lifespan ( 72 , 73 ), or cancer evolution ( 74 ). Bgee, by generating comparable reference sets of expression patterns in multiple species, and homology relations to link them, is the first resource to allow the systematic and automated comparison of gene expression patterns between species.…”

Transcriptomics unravels molecular players shaping dorsal lip hypertrophy in the vacuum cleaner cichlid, Gnathochromis permaxillaris

“…The reduced expression of foxp1 suggests a potential repressive effect on transcription of the genes induced in the hypertophic regions. Interestingly, foxp1 has been already demonstrated to have repressive effects on transcription of many of its downstream targets [ 98 – 100 ]. Moreover, a mutation affecting foxp1 function has been associated with hypertophy of vermilion borders (side edges) of upper lip in humans [ 37 ].…”