Early developmental changes of the lactate dehydrogenase isoenzyme pattern in mouse, rat, guinea-pig, Syrian hamster and rabbit

Preparing Muscles for Diving: Age-Related Changes in Muscle Metabolic Profiles in Harp (Pagophilus groenlandicus) and Hooded (Cystophora cristata) Seals

In adult marine mammals, muscles can sustain aerobic metabolism during dives in part because they contain large oxygen (O2) stores and metabolic rates are low. However, young pups have significantly lower tissue O2 stores and much higher mass-specific metabolic rates. To investigate how these differences may influence muscle function during dives, we measured the activities of enzymes involved in aerobic and anaerobic metabolic pathways (citrate synthase [CS], β-hydroxyacyl-coenzyme A dehydrogenase [HOAD], lactate dehydrogenase [LDH]) and the LDH isoform profile in six muscles from 41 harp (Pagophilus groenlandicus) and 30 hooded (Cystophora cristata) seals ranging in age from fetal to adult. All neonatal muscles had significantly higher absolute but lower metabolically scaled CS and HOAD activities than adults (∼ 70% and ∼ 85% lower, respectively). Developmental increases in LDH activity lagged that of aerobic enzymes and were not accompanied by changes in isozyme profile, suggesting that changes in enzyme concentration rather than structure determine activity levels. Biochemical maturation proceeded faster in the major locomotory muscles. In combination, findings suggest that pup muscles are unable to support strenuous aerobic exercise or rely heavily on anaerobic metabolism during early diving activities and that pups' high mass-specific metabolic rates may play a key role in limiting the ability of their muscles to support underwater foraging.

Ontogenic activities and interactions of the lactate dehydrogenase isozymes with cellular structure in the guinea pig

The LDH activities and isozyme distributions associated with soluble and particulate fractions of five major tissues have been followed during the development of the guinea pig. Evidence has been provided for an appreciable degree of interaction between LDH and cellular structure in all these tissues (liver, kidney, skeletal muscle, brain and heart) at all stages of development, but particularly in the early foetal stages. These data have been discussed in relation to the nature and extent of this binding and the correlations with the metabolic emphases in these tissue situations during development.

Influence of embryo size on lactate dehydrogenase isozyme expression in giant mouse chimaeras

Chimaeras consisting of 2, 4, 8 and up to 16 mouse embryos were formed at day 3 and cultured in vitro up to day 8. The influence of size and cell number on the activation of the embryonic genome for LDH-5 was studied in non-attaching giant chimaeric blastocysts and compared to control embryos implanting in vivo or growing out in vitro. Day 5 chimaeric blastocysts consisting of 4 to 8 embryos had a similar size as early in vivo egg cylinders, but still expressed exclusively LDH-1 as normal preimplantation embryos do. Only during further ageing of non-attaching chimaeric blastocysts, a few samples were positive for LDH-5. There is no convincing evidence that the experimental increase of the cell number triggers a premature activation of the embryonic LDH genes. These results are discussed in comparison to other possible mechanisms regulating stage-specific activation of the embryonic genome.

Ontogenic variations in the interactions of lactate dehydrogenase isozymes with cellular structure

The interactions of the LDH isozymes with cellular structure have been studied in the major tissues of the mouse during development. Overall, there is a clear indication that interactions between LDH and cellular structure are appreciable in all major tissues and at all stages of development, and an analysis of the isozyme status of the enzyme in both soluble and bound compartments has been effected. Information has been provided supporting the preferential binding of the A type activity to actin filaments. The data provided also support the concept of pelletable B type LDH in kidney and brain during the postnatal period. Binding was particularly extensive in the early embryonic stages, and the significance of this phenomenon, and the subcellular interactions observed to varying degrees in all the tissues throughout development, have been discussed in relation to the known metabolic characteristics of these separate tissue situations.

The ontogenic characteristics of lactate dehydrogenase isozymes in mammaliam pre-implantation ova

The onotgenic characteristics of lactate dehydrogenase (LDH) isozymes in mammalian pre-implantation ova have been reviewed. Evidence has been provided that the ova of mice and other mammalian species contain enzyme activity in a masked form, and display turnover processes which possess distinctive characteristics by comparison with those in adult tissues. Also, the extraordinary high levels of LDH in the extracellular secretion of the mammaliam oviduct have been commented on, along with the influence of reproductive hormones on the activity and type of this enzyme. In addition, attention has been drawn to the unique characteristics of the oval micro-evironment, and the influence which such factors may exert on the realization of enzyme phenotype during early mammalian development.

Expression of lactate dehydrogenase isozyme 5 (LDH-5) in cultured mouse blastocysts in the absence of implantation and outgrowth

Extensive extraction studies with Triton X-100 revealed only LDH-1 (B4) but no trace of LDH-5 (A4) in one-cell and two-cell mouse and rat embryos. The LDH isozyme pattern of preimplantation mouse embryos changes from the maternally inherited B subunit isozyme (LDH-1) to a pattern dominated by LDH-5 when mouse blastocysts are cultured under conditions that prevent hatching but allow trophoblast giant cell transformation. During differentiation of mouse blastocysts in vitro, implantation is therefore not essential for the appearance of the A subunit form of LDH (LDH-5) coded for by the embryonic genome. Mechanisms controlling the expression of LDH-5 in mouse blastocysts during in vivo development are discussed.

Lactate dehydrogenase in preimplantation rabbit embryos

Unfertilized eggs and early embryos up to the 2-day (16-cell) cleavage stage of development in the rabbit contain predominantly the most cathodal lactate dehydrogenase isoenzyme made up of A-type subunits. Following early cleavage there is a progressing increase in total LDH activity in the embryo as development proceeds through 4- and 6-day blastocyst stages. This is accompanied by an increase in the amount of B-type subunits and a concomitant shift in the lactate dehydrogenase isoenzyme electrophoretic pattern toward the anodal isoenzyme types.