Localization of lactate dehydrogenase activity in the cells of the fish (Xiphorphorus helleri) eye

Lactate dehydrogenase in teleosts. The role of LDH-C4 isozyme

1. Lactate dehydrogenase (LDH) occupies an important position in cell metabolism. 2. Teleosts possess at least three genetic loci coding for lactate dehydrogenase subunits, Ldh-A, Ldh-B and Ldh-c. LDH exists in most tissues in several isozymic forms. 3. The isozyme LDH-C4 is synthesized predominantly in regions of the nervous system concerned with the eye.

Kinetic studies on the lactate dehydrogenase (LDH-5) isozymes of brown trout, Salmo trutta L

The LDH-5 isozymes of brown trout, Salmo trutta L., were purified and subjected to enzyme kinetic analysis. A hierarchy of magnitude existed for both Km(pyr) and Km(lac) such that LDH-5(105/105) greater than (100/105) greater than (100/100). The results suggest that the 105 allele has been replaced by 100 at Ldh-5 under the action of natural selection.

Ontogeny of LDH-isozymes in Mexican Axolotl, Ambystoma mexicanum by thin-layer isoelectric focusing

The ontogeny of lactate dehydrogenase (LDH) isozymes in developing Mexican axolotl, Ambystoma mexicanum was investigated by thin-layer isoelectric focusing in polyacrylamide gel. The isoelectric points (pI values) of the isozymes were determined. The minor components generally remained masked during conventional electrophoresis, but became sharp as isofocusing progressed. We identified in developing eggs and embryos five major LDH isozymes, which could also be traced in the ovarian eggs. All these isozymes, except LDH-1, consisted of one major and one minor component. Heterogeneity in axolotl LDH is reported for the first time. The separated isozymes had pI values from 5.24-6.60. Contrary to observations made by others, it was found that the anodal forms of LDH (PIs 5.24-5.80) were prominent throughout, while the remainder (pIs 6.16-6.60) gradually lost their stainability. It thus appears that isoelectric focusing is a possible method for the analysis of protein mixtures and can be successfully applied to problems of differentiation.

Differential gene expression in multilocus isozyme systmes 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.