LDH Loci Research Articles

Differential gene expression in multilocus isozyme systems of the developing green sunfish

The patterns of expression of eight multilocous isozyme systems were investigated in the differentiated adult tissues and the early embryonic stages (0-210 hours after fertilization) of the green sunfish, Lepomis cyanellus. Enzymes encoded by approximately 23 gene loci were resolved by starch-gel electrophoresis and detected by specific histochemical staining. The developmental patterns of these isozyme systems appear to be the result of the diffential expression of the multiple gene loci. Isozymic forms of glucoseophosphate isomerase (GPI-A2), malate dehydrogenase (MDH-A2), and creatine kinase (CK-C2) were present in most differentiated tissues, in the unfertilized eggs, and in all stages of embryonic development. Closely homologous forms of these isozymes (GPI-B2, MDH-B2, and CK-A2) were expressed predominantly in skeletal muscle and were first detected at around the time of hatching (38-42 hours). The similar temporal and spatial patterns of gene expressions for the GPI, LDH, MDH, and CK loci suggest that the duplicates loci encoding enzymes, diverged in their regulation to patterns of differential gene expression which are similar for each enzyme system.

Specialized lactate dehydrogenase isozymes: the molecular and genetic basis for the unique eye and liver LDHs of teleost fishes.

AbstractElectrophoretic and immunochemical analysis of the lactate dehydrogenase isozyme patterns of fishes indicates that these isozymes are the tetrameric products of three LDH loci — A, B, and C — which are present in virtually all teleost fishes. The A and B genes of fishes and their corresponding isozymes have previously been shown to be homologous to the A and B genes of other vertebrates. The eye‐band LDH characteristic of many groups of teleosts, and the liver‐band LDH of gadoid and cyprinid fishes are shown in this report to be encoded in the same LDH locus, designated C. In different groups of fishes this third LDH gene (C) is extremely varied both with regard to its tissue‐specific regulation and with regard to the physical properties of its corresponding subunit. The electrophoretic mobility of the C4 isozyme ranges from highly anodal in some species to slightly cathodal in others while the mobilities of the A4 and B4 tetramers remain relatively constant. Most fish species express the A and B genes for LDH in nearly all tissues. In contrast, the C gene is highly restricted in tissue expression in most advanced teleosts where its isozymic products are found predominantly in the eye of some species or in the liver of others.

CYTOGENETIC ANALYSIS OF PSEUDOLINKAGE OF LDH LOCI IN THE TELEOST GENUS SALVELINUS

Cytological and genetic analyses provide evidence that spontaneous centric fusion and fission can account for curious patterns of pseudolinkage of two LDH loci in males of brook trout (Salvelinus fontinalis) and in the F(1), F(2) and backcross generations of lake trout (S. namaycush) x brook trout hybrids. Intraindividual polymorphisms for acrocentric and metacentric chromosomes in somatic and gonadal tissue of these fish have been related to the proposed polyploid evolution in Salmonidae.

Polymorphisms for LDH and Transferrin Loci in Brook Trout Populations

Abstract Seven hatchery populations and seven of eight wild populations of brook trout sampled were polymorphic for both the LDH-B and the transferrin loci. The degree of variations of allele frequencies as well as of the amount of heterozygosity was generally greater among hatchery fish than those from natural populations. Calculations of interpopulation heterogeneities of allele frequency differences permitted distinguishing all of the hatchery strains, but not all of the small wild populations, from each other. While gross intra-population heterogeneity was found, an assessment of the breeding structure of wild brook trout in a stream was not possible. Electrophoretic variants were found in wild populations for two other LDH polypeptides and for one other serum protein. From assumptions that five loci were polymorphic in 13 total loci studied, the estimate of proportion of polymorphic loci in wild brook trout is 38.4%. The similar estimate for hatchery strains is 15.4%.