Locus determining the human sperm-specific lactate dehydrogenase, LDHC, is syntenic with LDHA

From the data presented in this report, the human LDHC gene locus is assigned to chromosome 11. Three genes determine lactate dehydrogenase (LDH) in man. LDHA and LDHB are expressed in most somatic tissues, while expression of LDHC is confined to the germinal epithelium of the testes. A human LDHC cDNA clone was used as a probe to analyze genomic DNA from rodent/human somatic cell hybrids. The pattern of bands with LDHC hybridization is easily distinguished from the pattern detected by LDHA hybridization, and the LDHC probe is specific for testis mRNA. The structural gene LDHA has been previously assigned to human chromosome 11, while LDHB maps to chromosome 12. Studies of pigeon LDH have shown tight linkage between LDHB and LDHC leading to the expectation that these genes would be syntenic in man. However, the data presented in this paper show conclusively that LDHC is syntenic with LDHA on human chromosome 11. The terminology for LDH genes LDHA, LDHB, and LDHC is equivalent to Ldh1, Ldh2, and Ldh3, respectively.     

Detection of lactate dehydrogenase B4 in human hemolysate of patients deficient in lactate dehydrogenase B subunit activity using enzyme immunoassay

We developed a sensitive enzyme immunoassay system specific for human lactate dehydrogenase (LDH)- B₄ with antiacetylated LDH-B₄ Fab-horse-radish peroxidase conjugate. The enzyme immunoassay system was not interfered with by up to 0.3 mg/tube of hemoglobin. Thus, we measured LDH-B₄ concentrations in the hemolysate of seven heterozygous individuals deficient in LDH-B subunit activity and eight normal individuals. We could not find a significant difference between the LDH-B₄ concentrations in heterozygous and those in normal individuals. These results demonstrate that heterozygous individuals deficient in LDH-B subunit activity produce enzymatically inactive B subunits.This work was supported in part by grants in aid for Scientific Research from the Ministry of Education, Japan (59570998), and from the Clinical Pathology Research Foundation of Japan.     

Evolution of Cryptosporidium parvum lactate dehydrogenase from malate dehydrogenase by a very recent event of gene duplication

We have expressed the L-lactate dehydrogenase (LDH) and L-malate dehydrogenase (malDH) genes from the apicomplexan Cryptosporidium parvum (CpLDH1 and CpMalDH1) as maltose-binding protein (MBP) fusion proteins in Escherichia coli. The substrate specificities, enzymatic kinetics, and oligomeric states of these two parasite enzymes have been characterized. By taking advantage of recently completed and ongoing apicomplexan genome sequencing projects, we identified additional MalDH genes from Plasmodium spp., Toxoplasma gondii, and Eimeria tenella that were previously unavailable. All apicomplexan MalDHs appeared to be cytosolic and no organellar homologs were identified from the completely sequenced P. falciparum genome and other ongoing apicomplexan genome-sequencing projects. Using these expanded apicomplexan LDH and MalDH sequence databases, we reexamined their phylogenetic relationships and reconfirmed their relationship to alpha-proteobacterial MalDHs. All LDH and MalDH enzymes from apicomplexans were monophyletic within the LDH-like MalDH group (i.e., MalDH resembling LDH) as a sister to alpha-proteobacterial MalDHs. All apicomplexan LDHs, with the exception of CpLDH1, formed a separate clade from their MalDH counterparts, indicating that these LDHs were evolved from an ancestral apicomplexan MalDH by a gene duplication coupled with functional conversion before the expansion of apicomplexans. Finally, CpLDH1 was consistently placed together with CpMalDH1 within the apicomplexan MalDH cluster, confirming an early working hypothesis that CpLDH1 was probably evolved from the same ancestor of CpMalDH1 by a very recent gene duplication that occurred after C. parvum diverged from other apicomplexans.     

Regional localisations of VIM, HSD3b, ACTA1 and PGM1 in pigs

The comparative map between human and pig has progressed rapidly over the past 2 years. Nevertheless, some points still need to be clarified, particularly the correspondences between human chromosome 10 (HSA10) and porcine chromosome 10 (SSC10) and between human chromosome 1 (HSA1) and porcine chromosomes. The gene codings for vimentin (VIM) carried by HSA10 and three genes carried by HSA1 (hydroxy delta 5 steroid dehydrogenase 3 beta: HSD3B; alpha actin 1: ACTA1; and phosphoglucomutase 1: PGM1) were selected and the regional localisations on pig chromosomes were determined using a well-characterised somatic cell hybrid panel.     

An immunochemical method for the detection of the expression of human gene loci in human-rodent somatic cell hybrids with special reference to the GPI locus

Species-specific antibodies, prepared against unpurified human and Chinese hamster fibroblast extracts, were used to identify the parental origins of enzymes in human-hamster somatic cell hybrids. Results of the detection of the expression of the human glucosephosphate isomerase gene locus (GPI) by electrophoretic and immunochemical techniques were concordant in 17 instances. The human GPI synthesized by fibroblasts derived from skin explants and by somatic cell hybrids retaining the human GPI locus, regardless of whether the human parental cells were lymphocytes or fibroblasts, appeared to be antigenically identical.This work was supported by the Medical Research Council of Canada (Grant MA-4061). Personnel and operating support were provided by The Children's Hospital of Winnipeg Research Foundation, Inc.     

Further data on chromosomal assignments of pig enzyme loci LDHA, LDHB, MPI, PEPB and PGM1, using somatic cell hybrids

Summary. Clear interspecies differentiation between the chromosomes in pig-mouse somatic cell hybrids was achieved by using the THA-technique for the cytogenetic analysis. The assignments of LDHB and MPI to pig chromosomes nos 5 and 7 respectively, reported previously, were confirmed by analysis of 34 hybrid clones. The LDHA, PEPB and PGM1 genes were assigned to pig chromosomes nos 2, 5 and 6 respectively. Both LDHB and PEPB were indicated to be located on the long arm, except the most proximal part, of pig chromosome no. 5. The proposed synteny between LDHB and PEPB in pigs is in accordance with the synteny observed between these two loci in several other mammalian species.     

Fluorimetric quantification of intracellular lactate dehydrogenase during fermentation using flow injection analysis

A flow injection system for the on-line detection of the intracellular enzyme lactate dehydrogenase (LDH) during fermentation has been developed. The system is comprised of an on-line cell disintegration part, an immobilised dye based expanded bed column for the affinity capture of LDH and a fluorimetric detection unit. The system with a linearity of 0.1–5.4 U LDH ml^–1 was applied for the detection of intracellular accumulation of LDH during Lactococcus lactis subsp.lactis cultivation.     

Regional assignments of NP and MPI on chromosome 7 in pig, Sus scrofa

Summary. Fibroblasts from a pig with a spontaneous reciprocal translocation involving chromosome 7, were used to prepare a set of pig-mouse somatic cell hybrids. The isozyme analysis strongly indicated that in pigs, the NP (nucleoside phosphorylase) gene is located on the distal part of the long arm of chromosome 7, (q21-qter), while the MPI (mannose phosphate isomerase) gene is in the region q21-pter. This confirmed previously reported chromosomal assignment of these genes in pigs and that this synteny has been evolutionarily conserved in several different animal species.     

Cloning, sequence and expression of the lactate dehydrogenase gene from the human malaria parasite, Plasmodium vivax

Increased drug resistance to anti-malarials highlights the need for the development of new therapeutics for the treatment of malaria. To this end, the lactate dehydrogenase (LDH) gene was cloned and sequenced from genomic DNA of Plasmodium vivax ( PvLDH) Belem strain. The 316 amino acid protein-coding region of the PvLDH gene was inserted into the prokaryotic expression vector pKK223-3 and a 34 kDa protein with LDH activity was expressed in E. coli. Structural differences between human LDHs and PfLDH make the latter an attractive target for inhibitors leading to novel anti-malarial drugs. The sequence similarity between PvLDH and PfLDH (90% residue identity and no insertions or deletions) indicate that the same approach could be applied to Plasmodium vivax, the most common human malaria parasite in the world.     

Fifteen new synteny assignments of microsatellites to the bovine genome

A panel of 36 hamster-bovine hybrid cell lines was used to assign 15 bovine microsatellites. Locus identification, synteny group and/or chromosome assignment and registration number were as follows: ILSTS001 (U22, Chr07, D7S13), ILSTS002 (U09, Chr18, D18S7), ILSTS004 (U10, Chr01, D1S28), ILSTS005 (U05, Chr10, D10S25). ILSTS006 (U22, Chr07, D7S8), ILSTS008 (U24, Chr14, D14S15), ILSTS010 (U27, DU27S11), ILSTS011 (U24, Chr14, D14S16), ILSTS012 (U16, Chr11, D11S26), ILSTS015 (U07, Chr25, D25S3), ILSTS016 (U04, Chr21, D21S22), ILSTS017 (X, DXS11), ILSTS018 (U15, Chr06, D6S15), ILSTS019 (U07, Chr25, D25S7) and ILSTS020 (U05, Chr10, D10S27). These results contribute to the international effort to improve the bovine genetic map.     

Expression of the human adenylate kinase isozymes,phosphopyruvate hydratase, 6-phosphogluconate dehydrogenase,and phosphoglucomutase-1 in man-rodent somatic cell hybrids

The expression of the adenylate kinase isozymes and of phosphopyruvate hydratase was studied in man-mouse and man-hamster hybrid clones. Concordant segregation of the loci coding for AK-2 and PPH was observed in 54 of 55 primary hybrid clones, and these loci were demonstrated to be synthetic with the loci specifying PGM-1 and PGD. The pattern of expression of the four enzymes in discordant clones suggests the gene order 1pter-(PGD,PPH)-AK-2-PGM-1-centromere. In addition, AK-1 was found to be expressed independently of AK-2.This work was supported by the NIH Grants 5 PO1 HB 06276-04, HD 04807-06, and HD 06285-04.     

Regulation of the expression of lactate dehydrogenase isozymes in human lymphocytes

Mitogen activation of human peripheral lymphocytes leads to a switch in the isozymes of LDH; resting cells contain low activities of only the B₄ and B₃A forms, whereas activated cells contain high activities of the A₄ and A₃B forms. B₄ LDH is not altered in activated cells. In this study we show that the appearance of the A subunits occurs concomitantly with a several fold increase in the steady state levels of LDH-A mRNA. Responses in LDH-A mRNA are observed within 12 hrs of activation, and are, thus, associated with the G0/G1 transition or with early G1 (Marjanovicet al. Exp. Cell Res. (1991) 193: 425–431). Maximal expression of LDH-A mRNA requires both phorbol ester and concanavalin A, implying a complex regulatory pathway involving cascade systems activated through both the antigen receptor (TR) and protein kinase C.     

Estimating the number of viable animal cells in multi-well cultures based on their lactate dehydrogenase activities

A method is described for estimating the numbers ofanimal cells in multi-well culture by simultaneouslymeasuring the lactate dehydrogenase activity of thetotal culture and the medium. The difference betweenthe two reflects the dehydrogenase content of thecells and correlates with cell number. This LDH/INTmethod was tested using several lines of normal andtransformed suspension and adherent cells. Thelactate dehydrogenase activities of duplicate cultureswere determined colourimetrically using reactioncocktails containing lactate, NAD⁺, diaphorase,and p-iodonitrotetrazolium violet, with and withoutTriton X-100. The difference in absorbance at 490 nm(A₄₉₀ = A_{490, test} – A_{490, control}) was used to calculate the lactatedehydrogenase activity of the total culture (+ Triton)and the medium (– Triton). The cellular lactatedehydrogenase activity (difference between totaland medium dehydrogenaseactivities) was proportional to viable cell number. The effects on cell growth of four metabolicinhibitors, sodium azide, actinomycin D,cycloheximide, and taxol, were determined using theLDH/INT assay and direct cell counting. The inhibitorconcentrations that caused decreases in the LDHactivity and cell number by 50% were similar. TheLDH/INT assay is quick and sensitive, works equallywell for adherent and suspension cells, and providesinformation about LDH activities of both the mediumand cells. It is particularly useful for screeningpotential cell-growth inhibitors.     

LDH calcutta-1: A mutation of the B subunit of human lactate dehydrogenase

The electrophoretic variant of human LDH, Calcutta-1, occurs at phenotypic frequencies of 0–4% throughout India. The variant was examined by various electrophoretic techniques and by heat stability studies. The LD₁ (B₄) isoenzyme was purified from normal and variant bloods by affinity chromatography and ion-exchange chromatography. A minimum of five Calcutta-1 LD₁ bands was demonstrated by isoelectric focusing. Electrophoresis of variant LD₁ in high-molar urea-acrylamide denaturing gels resulted in two Calcutta-1 B subunit bands, while normal gels yielded only a single band. Homozygote Calcutta-1 LDH from red cells demonstrated a decreased heat stability, while heterozygote variant LDH showed a normal heat stability. This effect was confirmed when purified LD₁'s were compared. Evidence is presented suggesting a B-subunit variant showing thermolability in the homozygous form.The author was supported by an Australian National University Scholarship.     

Discovery of human lactate dehydrogenase 5 inhibitors (hLDH5) with anti-lung cancer activity through an in silico method and biological validation

Human lactate dehydrogenase 5 (hLDH5) is an important metabolic enzyme playing critical roles in the anaerobic glycolysis. Herein, we employed an in silico method and biological validation to identify a novel hLDH5 inhibitor with a promising cellular activity under hypoxia condition. The identified compound 9 bound to hLDH5 with a K_d value of 1.02 µM, and inhibited the enzyme with an EC₅₀ value of 0.7 µM. Compound 9 exhibited a weak potency against NCI-H1975 cell proliferation under normal condition (IC₅₀ = 36.5 µM), while dramatically increased to 5.7 µM under hypoxia condition. In line with the observation, hLDH5 expression in NCI-H1975 cell under hypoxia condition is much higher as compared to the normal oxygenated condition, indicating the hLDH5 inhibition may contribute to the cancer cell death.     

Polymorphism of A, B and C loci of lactate dehydrogenase in European fish species of the Cyprinidae family

In 24 fish species of the Cyprinidae family, belonging to 21 genera, isoenzyme patterns of lactate dehydrogenase (LDH) were determined, which could be classified in the majority of cases into 3 main groups. Isoenzyme patterns in natural hybrids of roach and rudd, roach and bream, roach and bleak were also analysed. In bitterling, polymorphism was observed in B locus of LDH. In white bream polymorphism exists in the A locus. In bream, rudd, silver carp and barbel polymorphism was found in C loci. Isoenzyme patterns indicate that in each case the polymorphism is genetically controlled by two alleles at a single locus. The populations investigated were in Hardy-Weinberg equilibrium. No significant differences were found in the activity of liver LDH in various polymorphic types of C loci of bream and rudd.     

Assignment of the gene governing cellular ouabain resistance to Mus musculus chromosome 3 using human/mouse microcell hybrids

Human/mouse microcell hybrids were used to establish the assignment of the gene governing resistance to the cardiac glycoside ouabain (Oua-1) to Mus musculus chromosome 3. Microcells were prepared from primary mouse embryo fibroblasts and fused with HeLa S3 cells, and microcell hybrids were isolated and maintained in medium containing 10^–6 m ouabain. Resistance to ouabain was not expressed concordantly with any of 26 murine isozyme markers. Karyotypic analysis of five primary clones showed that one to five murine chromosomes had been transferred from donor to recipient in these experiments. Only mouse chromosome 3 was common to all ouabain-resistant primary clones. Both ouabain-resistant and -sensitive subclones were isolated from hybrids grown in the absence of selective pressure, and karyotyping showed that loss of resistance to ouabain was concordant with the loss of murine chromosome 3.These studies were supported by Grant GM9966 from the National Institutes of Health.     

Chinese hamster x American mink somatic cell hybrids: characterization of a clone panel and assignment of the mink genes for malate dehydrogenase,NADP-1 and malate dehydrogenase,NAD-1

Summary Chinese hamster x American mink somatic cell hybrids were obtained and examined for chromosome content and expression of mink malate dehydrogenase, NADP (MOD-1; EC 1.1.1.40), malate dehydrogenase, NAD (MOR-1; EC 1.1.1.37), glucose-6-phosphate dehydrogenase (G6PD; EC 1.1.1.49) and hypoxanthine phosphoribosyltransferase (HPRT; EC 2.4.2.8). All the hybrid clones examined were found to segregate mink chromosomes. A clone panel containing 25 clones was set up. The possibilities and limitations of this panel for mink gene mapping are analysed. Using this panel, it is feasible to rapidly map genes located on chromosomes 1–13 and to provisionally assign genes located on chromosome 14 and the X. Based on the data obtained, the genes for MOD-1 and MOR-1 were firmly assigned to mink chromosomes 1 and 11, respectively, and the genes for G6PD and HPRT were provisionally assigned to the X.     

An immunochemical analysis of the novel liver-restricted LDH activity from cichlid fishes (Cichlidae: Teleostei) confirms its non-orthology with piscine LDH-C

In an electrophoretic survey of lactate dehydrogenase (LDH) isozymes in neotropical cichlid fishes (Perciformes: Cichlidae) several species were discovered in which a cathodal liver-restricted isozyme is expressed along with the highly anodal eye-restricted isozyme (LDH-C₄) typically encountered in perciform fishes. Biochemical characterization of these two isozymes from the basketmouth cichlid, Acaronia nassa (Heckel), strongly suggested that they were non-orthologous and challenged the accepted view that eye- and liver-restricted LDH isozymes are alternative expressions of the same (LDH-C *) gene. In this study, antiserum raised against cypriniform (goldfish) liver-restricted LDH-C₄ failed to cross-react with the basketmouth liver-restricted analogue while effectively titrating the eye-restricted, anodal isozyme and, at higher titres, the LDH-B₄, heart-restricted isozyme from all cichlid species. Anti-serum raised against basketmouth muscle-restricted LDH-A₄ failed to titrate any of the eye- and liver-restricted isozymes. These data confirm the orthology of eye- and liver-restricted LDH isozymes in Cypriniform and Perciform fishes as originally proposed, suggest that the liver-restricted isozyme of cichlid fishes is non-orthologous and further raise the question of identity and evolutionary origin of this anomalous LDH activity.