Linkage group V of platyfishes and Swordtails of the genus Xiphophorus (Poeciliidae): linkage of loci for malate dehydrogenase-2 and esterase-1 and esterase-4 with a gene controlling the severity of hybrid melanomas.
Electrophoretic variations ascribable to three enzyme loci coding for esterase-1 and -4 (ES1 and ES4) and a malate dehydrogenase-2 isozyme (MDH2) were studied in interspecific backcrosses of fishes of the genus Xiphophorus (Poeciliidae). Normal segregation was demonstrated for all three loci. Linkage analyses indicated a gene order of ES1-6%-ES4-33%-MDH2. This group [designated linkage group (LG) V] was shown to assort independently from the 11 loci comprising LG's I-IV and from 18 other informative markers, with the limits of the data. A factor controlling the extent of development of inherited melanomas was demonstrated to be associated only with LG V loci, implying predominant control by a single gene, which probably determines the completeness of differentiation of macromelanophores in hybrids. Possible explanations for variability in the apparent chromosomal position of the melanoma severity gene, as assessed by estimates of recombination with the LG V enzyme loci, are discussed.
D000818:Animals; D043182:Carboxylesterase; D002265:Carboxylic Ester Hydrolases / Q000235:genetics* / Q000302:isolation & purification; D003433:Crosses, Genetic; D004592:Electrophoresis, Starch Gel; D005260:Female; D005393:Fish Diseases / Q000235:genetics*; D005399:Fishes / Q000235:genetics; D008040:Genetic Linkage; D006801:Humans; D008291:Malate Dehydrogenase / Q000235:genetics* / Q000302:isolation & purification; D008297:Male; D008545:Melanoma / Q000662:veterinary*; D010641:Phenotype
D008291:Malate Dehydrogenase; D002265:Carboxylic Ester Hydrolases; D043182:Carboxylesterase