title: Disappearing scales in carps: re-visiting Kirpichnikov's model on the genetics of scale pattern formation.
abstract: The body of most fishes is fully covered by scales that typically form tight, partially overlapping rows. While some of the genes controlling the formation and growth of fish scales have been studied, very little is known about the genetic mechanisms regulating scale pattern formation. Although the existence of two genes with two pairs of alleles (S&s and N&n) regulating scale coverage in cyprinids has been predicted by Kirpichnikov and colleagues nearly eighty years ago, their identity was unknown until recently. In 2009, the 'S' gene was found to be a paralog of fibroblast growth factor receptor 1, fgfr1a1, while the second gene called 'N' has not yet been identified. We re-visited the original model of Kirpichnikov that proposed four major scale pattern types and observed a high degree of variation within the so-called scattered phenotype due to which this group was divided into two sub-types: classical mirror and irregular. We also analyzed the survival rates of offspring groups and found a distinct difference between Asian and European crosses. Whereas nude × nude crosses involving at least one parent of Asian origin or hybrid with Asian parent(s) showed the 25% early lethality predicted by Kirpichnikov (due to the lethality of the NN genotype), those with two Hungarian nude parents did not. We further extended Kirpichnikov's work by correlating changes in phenotype (scale-pattern) to the deformations of fins and losses of pharyngeal teeth. We observed phenotypic changes which were not restricted to nudes, as described by Kirpichnikov, but were also present in mirrors (and presumably in linears as well; not analyzed in detail here). We propose that the gradation of phenotypes observed within the scattered group is caused by a gradually decreasing level of signaling (a dose-dependent effect) probably due to a concerted action of multiple pathways involved in scale formation.
authors.affiliation: Reproductive Genomics Group, Strategic Research Program, Temasek Life Sciences Laboratory, Singapore, Singapore.
authors.forename: Laura
authors.initials: L
authors.lastname: Casas
authors.affiliation: Department of Animal Sciences and Animal Husbandry, Georgikon Faculty, University of Pannonia, Keszthely, Hungary.
authors.forename: Réka
authors.initials: R
authors.lastname: Szűcs
authors.affiliation: Reproductive Genomics Group, Strategic Research Program, Temasek Life Sciences Laboratory, Singapore, Singapore.
authors.forename: Shubha
authors.initials: S
authors.lastname: Vij
authors.affiliation: Fish Facility, Temasek Life Sciences Laboratory, Singapore, Singapore.
authors.forename: Chin Heng
authors.initials: CH
authors.lastname: Goh
authors.affiliation: Reproductive Genomics Group, Strategic Research Program, Temasek Life Sciences Laboratory, Singapore, Singapore.
authors.forename: Purushothaman
authors.initials: P
authors.lastname: Kathiresan
authors.affiliation: Department of Animal Sciences and Animal Husbandry, Georgikon Faculty, University of Pannonia, Keszthely, Hungary.
authors.forename: Sándor
authors.initials: S
authors.lastname: Németh
authors.affiliation: Research Institute for Fisheries, Aquaculture and Irrigation, Szarvas, Hungary.
authors.forename: Zsigmond
authors.initials: Z
authors.lastname: Jeney
authors.affiliation: Department of Animal Sciences and Animal Husbandry, Georgikon Faculty, University of Pannonia, Keszthely, Hungary.
authors.forename: Miklós
authors.initials: M
authors.lastname: Bercsényi
authors.affiliation: Reproductive Genomics Group, Strategic Research Program, Temasek Life Sciences Laboratory, Singapore, Singapore ; Department of Animal Sciences and Animal Husbandry, Georgikon Faculty, University of Pannonia, Keszthely, Hungary ; Department of Biological Sciences, National University of Singapore, Singapore, Singapore.
authors.forename: László
authors.initials: L
authors.lastname: Orbán
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000235:genetics*; D002347:Carps / Q000235:genetics*; D005260:Female; D005838:Genotype; D008297:Male; D008957:Models, Genetic; D010641:Phenotype