Isozyme patterns of salmoid fishes: evidence for multiple cistrons for lactate dehydrogenase polypeptides

Comparative protein profiles: potential molecular markers from spermatozoa of Acipenseriformes (Chondrostei, Pisces)

Sturgeon and paddlefish (Acipenseriformes), the source of roe consumed as caviar, are a unique and commercially valuable group of ancient fishes. In this study, comparative proteomics was used to analyze protein profiles of spermatozoa from five sturgeon species and one paddlefish: Siberian sturgeon (Acipenser baerii), sterlet (A. ruthenus), Russian sturgeon (A. gueldenstaedtii), starry sturgeon (A. stellatus), beluga (Huso huso), and Mississippi paddlefish (Polyodon spathula). Protein profiles of spermatozoa were determined by isoelectric focusing and two-dimensional electrophoresis (2-DE) high-resolution gels. The peptides, previously selected by 2-DE analysis as potentially species-specific, were obtained by "in-gel" tryptic digestion, followed by matrix-associated laser desorption/ionization time-of-flight/mass spectrometry (MALDI-TOF/MS). Among the 23 protein spots selected, 14 were identified as isoforms of enolase B present in all species, but with different isoelectric points or molecular mass. Exceptions were A. ruthenus and H. huso, species with a close phylogenetic relationship. Glycerol-3-phosphate dehydrogenase was detected exclusively in P. spathula. Phosphoglycerate kinase was detected only in A. ruthenus and H. huso, and 3 additional proteins (fructose bisphosphate aldolase A-2, glycogen phosphorylase type IV and glyceraldehyde-3-phosphate dehydrogenase) were found exclusively in A. gueldenstaedtii and H. huso. This study points to the application of proteomics for differential characterization and comparative studies of acipenseriform species at the molecular level.

Purification and some properties of two creatine kinase isoforms from herring (Clupea harengus) spermatozoa

Creatine kinase (CK, EC 2.7.3.2) isoforms play important role in energy homeostasis and together with easily diffusible compounds like creatine and phosphocreatine maintain a cellular energy buffer and intracellular energy transport system. The CK activity in spermatozoa is the highest from all studied tissues in herring. It was detected that the two CK isoforms, CK1 and CK2, are characteristic only for spermatozoa and are not expressed in other herring tissues. Isolation and purification procedures allowed obtaining purified enzymes with specific activity of the 345 micromol/min/mg for CK1 and 511 micromol/min/mg for CK2. Native Mr's of the CK1 and CK2 determined by gel permeation chromatography were about 330,000 and 90,000, respectively. These results indicate that CK1 form has octameric structure and CK2 is a dimer mostly characteristic for cytosolic CK enzymes. In immunoblotting studies with antisera against CK2, the response was observed for CK2 and there was no response for CK1 and two other isoforms from herring skeletal muscle. These findings make the herring isoforms an interesting model for studies on the fish CK biochemical properties.

Multiple isoforms and an unusual cathodic isoform of creatine kinase from channel catfish (Ictalurus punctatus)

In vertebrates, the creatine kinase (CK) family consists of two cytosolic and two mitochondrial isoforms. The two cytosolic isoforms are the muscle type (M-CK) and the brain type (B-CK). Here we report multiple CK isoenzymes in the diploid channel catfish (Ictalurus punctatus) with one unusual cathodic isoform that was previously found only in pathological situations in human. The cathodic CK isoform existed only in the channel catfish stomach, ovary, and spleen, but not in any other species analyzed such as tilapia, smallmouth bass, chicken, or rat. Two genes encode the multiple forms of the channel catfish M-CK cDNAs. M-CK1 has three alleles, M-CK1.1, M-CK1.2, and M-CK1.3, while M-CK2 has just one allele as determined by analysis of 17 cDNA clones and by allele-specific PCR. M-CK1 encodes a protein of 381 amino acids and the M-CK2 cDNA encodes a protein of 380 amino acids. The two cDNAs shared an 86% identity and both have the nine diagnostic boxes for cytosolic CKs and thus are of cytosolic origin. The M-CK1 gene was isolated, sequenced, and characterized and its promoter should be useful for transgenic research for muscle-specific expression.

Some aspects of isozymes of lactate dehydrogenase, malate dehydrogenase and glucosephosphate isomerase in fish

1. The present paper reports some aspects of the isozymes of LDH, MDH and GPI in fish. 2. In Petromyzontiformes LDH is encoded by a single Ldh-A gene locus. In Myxiniformes and in most vertebrates LDH is encoded by two gene loci, A and B. A third Ldh-C locus is characteristic of the bony fishes Actinopterygii. 3. In fish the MDH isozymes are generally encoded by three gene loci Mdh-M, Mdh-A and Mdh-B. 4. In most diploid bony fish the GPI is controlled by two independent gene loci Gpi-A and Gpi-B. 5. The relationships of isozymes with evolution of vertebrates, tissual specificity, ontogenetic changes, with physiological and metabolic roles are discussed.

Coexpression of distinct eye- and liver-specific LDH isozymes in cichlid fish

In a recent electrophoretic survey of lactate dehydrogenase (LDH) in neotropical cichlid fishes (Perciformes, Cichlidae) we have discovered several species in which a cathodal liver-specific isozyme is expressed along with the highly-anodal eye-specific isozyme (LDH-C4) typically encountered in perciform fishes. We believe this fourth, liver-specific LDH isozyme to be real and not artifactual since homogenization of fresh liver from one of these species, the Basketmouth cichlid (Acaronia nassa), in either of two nondenaturing detergents or in the presence of the protease inhibitor phenylmethylsulfonylfluoride affects neither the presence nor mobility of this cathodal band. Moreover, it continues to be expressed in the captively bred F1 of these same wild fish. The discovery of several fish species, like the Basketmouth, in which biochemically distinct eye- and liver-specific LDH isozymes are coexpressed, is discussed in light of the currently accepted hypothesis that these two isozymes are encoded by a single locus (LDH-C) which has undergone divergent tissue expression in several other major teleost groups. Preliminary characterization of the liver-specific isozyme relative to the eye-specific LDH-C4 in the Basketmouth cichlid with respect to thermolability and NADH-induced binding to oxamate-sepharose columns suggests that the eye- and liver-specific LDH isozymes are biochemically quite distinct in this fish and that they are probably encoded by two distinct loci.

Phosphoglucose isomerase isozymes and allozymes of the brown trout, Salmo trutta L

1. In brown trout the Pgi-1 and Pgi-2 loci are predominantly expressed in white skeletal muscle; Pgi-3 being mainly expressed in most other tissues. 2. Total PGI activity determinations revealed that the allele formerly designated Pgi-2(65) is a null allele, Pgi-2(n). 3. Enzyme kinetic studies on the partially purified PGI homodimeric isozymes revealed that from 5 to 25 degrees C both PGI-1 and PGI-2 had significantly higher mean Km(F6P) values compared to PGI-3. 4. Distinct metabolic roles for the "muscle" (PGI-1, PGI-2) and "liver" (PGI-3) isozymes are proposed. 5. Significant Km (F6P) differences were found among the PGI-2 allozymes and among the PGI-3 allozymes.

Analysis of malate dehydrogenase isozymes from anuran amphibian ovary by isoelectric focusing

The isozymes patterns of ovarian malate dehydrogenase (MDH) from various anuran amphibian series were analyzed by isoelectric focusing (IEF). Extensive variability was observed in both the soluble (sMDH) and mitochondrial (mMDH) patterns with as few as two and as many nine bands being visualized in different species. The mean pIs for sMDH ranged from 4.5 to 8.3 and those for mMDH fell between 5.1 and 8.2. The sMDHs are considerably more heat labile in Rana species living in northern latitudes compared to those from southern states. Inhibition with p-chlormercuribenzoate (PCMB) revealed the importance of sulfhydryl groups for the activity of sMDHs, while the functional requirement for these groups in mMDHs appears to be of lesser importance. Observations from these studies lend support to the accumulating evidence that Rana pipiens from such southern locations as New Mexico may have undergone speciation.

Electrophoretic variation in muscle lactate dehydrogenase in Snake Valley cutthroat trout, Salmo clarki subsp

1. Electrophoretic variation observed in muscle A group lactate dehydrogenase in Snake Valley cutthroat trout (Salmo clarki subsp.) suggested the presence of two variant alleles at the A1 locus and a null allele at the A2 locus. 2. The taxonomic status of the Snake Valley cutthroat trout was reviewed.

Gene duplication in salmonid fishes: evidence for duplicated but catalytically equivalent A4 lactate dehydrogenases

Skeletal muscle tissues from many species of salmonid fish are known to exhibit a set of three of five isozymes for A4-type lactate dehydrogenase (L-lactate: NAD oxidoreductase, E.C. 1.1.1.27), but the genetic basis for this isozyme system has not previously been assessed. This isozyme system was purified to homogeneity from salmon (Oncorhynchus tshawytscha) and shown to be composed of two polypeptides. Aalpha and Abeta, in binomial tetrameric combinations. Amino acid analysis revealed that Aalpha and Abeta are closely related but genetically distinct proteins, and thus are coded for the recently duplicated structural loci. Catalytic studies on the purified intact salmon isozyme system and on the isozymically pure Aalpha4 and Abeta4 homotetramers from brown trout (Salmo trutta) revealed no significant differences in catalytic properties among these enzymes, suggesting equivalent catalytic function of Aalpha and Abeta. These results, in combination with studies on polypeptide and isozyme ratios, suggest that one of the duplicated loci in salmon may be drifting toward a nonfunctional state by accumulation of mutations in regulatory DNA rather than in the structural gene itself.