BAC Recombineering of the Agouti Loci from Spotted Gar and Zebrafish Reveals the Evolutionary Ancestry of Dorsal-Ventral Pigment Asymmetry in Fish.

J Exp Zool B Mol Dev Evol 2017 Nov 24;328(7):697-708. Epub 2017 May 24.

Instituto de Investigaciones Marinas, CSIC, Vigo, Spain.

Dorsoventral pigment patterning, characterized by a light ventrum and a dark dorsum, is one of the most widespread chromatic adaptations in vertebrate body coloration. In mammals, this countershading depends on differential expression of agouti-signaling protein (ASIP), which drives a switch of synthesis of one type of melanin to another within melanocytes. Teleost fish share countershading, but the pattern results from a differential distribution of multiple types of chromatophores, with black-brown melanophores most abundant in the dorsal body and reflective iridophores most abundant in the ventral body. We previously showed that Asip1 (a fish ortholog of mammalian ASIP) plays a role in patterning melanophores. This observation leads to the surprising hypothesis that agouti may control an evolutionarily conserved pigment pattern by regulating different mechanisms in mammals and fish. To test this hypothesis, we compared two ray-finned fishes: the teleost zebrafish and the nonteleost spotted gar (Lepisosteus oculatus). By examining the endogenous pattern of asip1 expression in gar, we demonstrate a dorsoventral-graded distribution of asip1 expression that is highest ventrally, similar to teleosts. Additionally, in the first reported experiments to generate zebrafish transgenic lines carrying a bacterial artificial chromosome (BAC) from spotted gar, we show that both transgenic zebrafish lines embryos replicate the endogenous asip1 expression pattern in adult zebrafish, showing that BAC transgenes from both species contain all of the regulatory elements required for regular asip1 expression within adult ray-finned fishes. These experiments provide evidence that the mechanism leading to an environmentally important pigment pattern was likely in place before the origin of teleosts.

Download full-text PDF

Source
http://dx.doi.org/10.1002/jez.b.22748DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5653409PMC
November 2017
86 Reads

Publication Analysis

Top Keywords

asip1 expression
16
spotted gar
12
ray-finned fishes
8
pigment pattern
8
expression
5
pattern
5
asip1
5
zebrafish
5
hypothesis compared
4
compared ray-finned
4
test hypothesis
4
fish test
4
pattern regulating
4
regulating mechanisms
4
mechanisms mammals
4
mammals fish
4
nonteleost spotted
4
examining endogenous
4
endogenous pattern
4
pattern asip1
4

Altmetric Statistics

Similar Publications