PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Pyruvate Synthase”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources
PubMed2001

The isolation and characterisation of a Saccharomyces cerevisiae gene (LIP2) involved in the attachment of lipoic acid groups to mitochondrial enzymes.

Lipoic acid is an essential cofactor for a variety of mitochondrial enzymes. We have characterised a gene from Saccharomyces cerevisiae which appears to encode a protein involved in the attachment of lipoic acid groups to the pyruvate dehydrogenase and glycine decarboxylase complexes. The predicted protein product of this gene has significant identity to the lipoyl ligase B of both Escherichia coli and Kluyveromyces lactis. A strain harbouring a null allele of this S. cerevisiae gene is respiratory deficient due to inactive pyruvate dehydrogenase, and is unable to utilise glycine as a sole nitrogen source.

Acyltransferases↗
PubMed1991

Interactive effects of thyroxine and experimental location on running endurance, tissue masses, and enzyme activities in captive versus field-active lizards (Sceloporus undulatus).

This study investigates the effects of exogenous thyroxine (T4) on running endurance, tissue masses, and the activities of citrate synthase (CS), pyruvate kinase (PK), cytosolic alpha-glycerophosphate dehydrogenase (alpha-GPDH), and beta-hydroxyacyl Coenzyme A dehydrogenase (HOAD) in Sceloporus undulatus (eastern fence lizard). The enzymes were assayed to indicate maximal catabolic activities that support exercise. Parallel experiments were done on captive and field-active groups to determine whether responses in captive studies adequately predict responses in nature. Exogenous T4 was administered via intraperitoneal pellets. The effect of T4 on running endurance was dependent on the location of the experiment (P = 0.040) such that stamina was increased by T4 only in field-active lizards. At lower levels of biological organization, interactivity between T4 and experimental location was evident but less prevalent than at the level of the whole animal, and some location effects occurred independent of T4 treatment. Heart and kidney masses were significantly greater and total hind leg muscle mass was less in captive than in field-active lizards. Thyroxine reduced liver mass in both locations and kidney mass only in captive lizards. Mass-specific CS and alpha-GPDH in gastrocnemius muscle (mixed fiber type) and HOAD in heart were lower in captive than in field-active lizards; PK in heart and liver and alpha-GPDH in heart were higher in captive lizards. Thyroxine increased CS in liver and HOAD in heart, decreased alpha-GPDH in liver in both locations, and decreased alpha-GPDH in gastrocnemius only in captive lizards. The effects of T4 differed significantly between experimental locations in gastrocnemius muscle (T4 decreased PK only in captive lizards) and in liver (T4 increased PK in field-active lizards and decreased PK in captive lizards). The mechanistic basis of differences in stamina between captive and field-active and between placebo and T4-treated lizards is largely unexplained by the factors measured here, thus illustrating the uncertainty of predicting organismal performance from lower level measurements. Nonetheless, T4 has now been shown to have greater physiological activity in field-active than in captive Sceloporus with regard to resting and total daily metabolic rates and running endurance. The results of this study further confirm that endocrine experiments on captive animals may not predict responses in nature. Further efforts to clarify the physiological significance of seasonal variations in levels of thyroid hormones will have to involve, at least in part, invasive studies on field-active lizards.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1980

Regional and subcellular distribution of ATP-citrate lyase and other enzymes of acetyl-CoA metabolism in rat brain.

The activities of ATP-citrate lyase in frog, guinea pig, mouse, rat, and human brain vary from 18 to 30 mu mol/h/g of tissue, being several times higher than choline acetyltransferase activity. Activities of pyruvate dehydrogenase and acetyl coenzyme A synthetase in rat brain are 206 and 18.4 mu mol/h/g of tissue, respectively. Over 70% of the activities of both choline acetyltransferase and ATP-citrate lyase in secondary fractions are found in synaptosomes. Their preferential localization in synaptosomes and synaptoplasm is supported by RSA values above 2. Acetyl CoA synthetase activity is located mainly in whole brain mitochondria (RSA, 2.33) and its activity in synaptoplasm is low (RSA, 0.25). The activities of pyruvate dehydrogenase, citrate synthase, and carnitine acetyltransferase are present mainly in fractions C and Bp. No pyruvate dehydrogenase activity is found in synaptoplasm. Striatum, cerebral cortex, and cerebellum contain similar activities of pyruvate dehydrogenase, citrate synthase, carnitine acetyltransferase, fatty acid synthetase, and acetyl-CoA hydrolase. Activities of acetyl CoA synthetase, choline acetyltransferase and ATP-citrate lyase in cerebellum are about 10 and 4 times lower, respectively, than in other parts of the brain. These data indicate preferential localization of ATP-citrate lyase in cholinergic nerve endings, and indicate that this enzyme is not a rate limiting step in the synthesis of the acetyl moiety of ACh in brain.

ATP Citrate (pro-S)-Lyase↗
PubMed1996

Mechanistic studies on the 8-amino-7-oxopelargonate synthase, a pyridoxal-5'-phosphate-dependent enzyme involved in biotin biosynthesis.

The reaction mechanism of 8-amino-7-oxopelargonate (8-amino-7-oxononoate) synthase from Bacillus sphaericus, an enzyme dependent on pyridoxal 5'-phosphate (pyridoxal-P), which catalyzes the condensation of L-alanine with pimeloyl-CoA, the second step of biotin biosynthesis, has been studied. To facilitate mechanistic studies, an improved over-expression system in Escherichia coli, and a new continuous spectrophotometric assay for 8-amino-7-oxopelargonate synthase were designed. In order to discriminate between the two plausible basic mechanisms that can be put forth for this enzyme, that is: (a) formation of the pyridoxal-P-stabilized carbanion by abstraction of the C2-H proton of the alanine-pyridoxal-P aldimine, followed by acylation and decarboxylation, and (b) formation of the carbanion by decarboxylation followed by acylation, the fate of the C2-H proton of alanine during the course of the reaction has been examined using 1H NMR. Spectra of the 8-amino-7-oxopelargonate formed using either L-[2-2H]alanine in H2O or L-alanine in D2O, showed that the C2-H proton of alanine is lost during the reaction and that the C8-H proton of 8-amino-7-oxopelargonate is derived from the solvent, a result that is only consistent with mechanism (a). Furthermore 8-amino-7-oxopelargonate synthase catalyzes, in the absence of pimeloyl-CoA, the stereospecific exchange, with retention of configuration, of the C2-H proton of L-alanine with the solvent protons. Similarly, 8-amino-7-oxopelargonate synthase catalyzes the exchange of the C8-H proton of 8-amino-7-oxopelargonate. In addition to these exchange reactions, 8-amino-7-oxopelargonate synthase catalyzes an abortive transamination yielding an inactive pyridoxamine 5'-phosphate (pyridoxamine-P) form of 8-amino-7-oxopelargonate synthase and pyruvate. Kinetic analysis gave a rate constant of kexch. = 1.8 min-1 for the exchange reaction which is 10 times lower than the catalytic constant and a rate constant of ktrans. = 0.11 h-1 for the transamination. Finally deuterium kinetic isotope effects (KIE) were measured at position 2 of L-alanine (DV = 1.3) and in D2O (D2OV = 4.0). The magnitudes of the KIE are consistent with a partially rate-limiting abstraction of the C2-H proton of alanine and a partially rate-limiting reprotonation step. Taken together, all these results show that 8-amino-7-oxopelargonate synthase utilizes mechanism (a). 8-Amino-7-oxopelargonate synthase and 5-aminolevulinate synthase, which has also been shown to use mechanism (a), belong to a class of pyridoxal-P-dependent enzymes that catalyze the formation of alpha-oxoamines. Based on the fact that all these alpha-oxoamine synthases share strong sequence similarities, we postulate that they also share the same reaction mechanism.

Acyl Coenzyme A↗
PubMed1980

Purification and Characterization of the Crown Gall-specific Enzyme, Octopine Synthase.

A single enzyme catalyzes the synthesis of all four N(2)-(1-carboxyethyl)-amino acid derivatives found in a crown gall tumor tissue induced by Agrobacterium tumefaciens (E. F. Sm. and Town.) Conn strain B6 on sunflower (Helianthus annuus L.). This enzyme, octopine synthase, has been purified by ammonium sulfate fractionation and chromatography on diethylaminoethylcellulose, blue agarose, and hydroxylapatite. The purified enzyme has all the N(2)-(1-carboxyethyl)-amino acid synthesizing activities found in crude preparations, and the relative activities with six amino acids remain nearly constant during purification. Although the maximum velocities (V) and Michaelis constants (K(m)) differ, the ratio V/K(m) is the same for all amino acid substrates. Thus an equimolar mixture of amino acids will give rise to an equimolar mixture of products. The kinetic properties of the enzyme are consistent with a partially ordered mechanism with arginine (NADPH, then arginine or pyruvate). Octopine synthase is a monomeric enzyme with a molecular weight of 39,000 by gel filtration and 38,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Journal Article↗
PubMed2003

Listeria intracellular growth and virulence require host-derived lipoic acid.

Listeria monocytogenes is a Gram-positive intracytosolic pathogen that causes severe disease in pregnant and immunocompromised individuals. We found that L. monocytogenes lacking the lipoate protein ligase LplA1 was defective for growth specifically in the host cytosol and was less virulent in animals by a factor of 300. A major target for LplA1, the E2 subunit of pyruvate dehydrogenase (PDH), lacked a critical lipoyl modification when the DeltalplA1 strain was grown intracellularly, which suggests that abortive growth was due to loss of PDH function. Thus, the use of host-derived lipoic acid may be a critical process for in vivo replication of bacterial pathogens.

Animals↗
PubMed1997

In vitro Tn7 mutagenesis of Haemophilus influenzae Rd and characterization of the role of atpA in transformation.

Haemophilus influenzae Rd is a gram-negative bacterium capable of natural DNA transformation. The competent state occurs naturally in late exponential growth or can be induced by a nutritional downshift or by transient anaerobiosis. The genes cya, crp, topA, and sxy (tfoX) are known to function in the regulation of competence development. The phosphoenolpyruvate:carbohydrate phosphotransferase system functions to maintain levels of cyclic AMP necessary for competence development but is not directly involved in regulation. The exact signal(s) for competence and the genes that mediate the signal(s) are still unknown. In an effort to find additional regulatory genes, H. influenzae Rd was mutated by using an in vitro Tn7 system and screened for mutants with a reduced ability to induce the competence-regulatory gene, comA. Insertions in atpA, a gene coding for the alpha subunit of the F1 cytoplasmic domain of the ATP synthase, reduce transformation frequencies about 20-fold and cause a significant reduction in expression of competence-regulatory genes, while the expression of constitutive competence genes is only minimally affected. In addition, we found that an insertion in atpB, which encodes the a subunit of the F0 membrane-spanning domain, has a similar effect on transformation frequencies.

Bacterial Proteins↗
PubMed1993

Properties of a lactate-induced relaxation in human placental arteries and veins.

OBJECTIVE: Our purpose was to determine the vasoactive effects and mechanism of action of lactate in human placental vessels by means of isometric muscle bath studies. STUDY DESIGN: Isolated 1 to 2 mm human placental arteries and veins from normal term pregnancies, precontracted with prostaglandin F2 alpha and incubated under a PO2 of approximately 35 torr were exposed to lactate, 1 to 10 mmol/L, (pH 7.4), pyruvate, hydrogen peroxide, nitroglycerin, or forskolin. The effects of endothelium removal or inhibitors of cyclooxygenase (indomethacin 10 mumol/L) and L-arginine metabolism (nitro-L-arginine 30 mumol/L) on the response to lactate and the effects of an antagonist of guanylate cyclase activation (methylene blue 10 mumol/L), cyanide (1 mmol/L), and hypoxia (PO2 8-10 torr) on responses to all agents were determined by analysis of variance and t test statistics. RESULTS: Lactate-elicited dose-dependent relaxation was not inhibited by endothelium removal, indomethacin, or nitro-L-arginine but was attenuated by methylene blue, cyanide, and hypoxia. Relaxation to hydrogen peroxide was inhibited by methylene blue and cyanide but not hypoxia. Relaxation to nitroglycerin was inhibited only by methylene blue, and relaxation to forskolin was not inhibited by these probes. Pyruvate did not produce a significant relaxation. CONCLUSIONS: These findings suggest that lactate causes relaxation in the human placental vessels by an oxygen and cyclic guanosine-3':5'-monophosphate-dependent mechanism, which may involve the generation of hydrogen peroxide but not the metabolism of arginine. Lactate-induced dilatation may be of importance during labor and in situations of acute and chronic fetal hypoxia.

Analysis of Variance↗
PubMed1992

Morphologic, biochemical, and cytogenetic studies of bone marrow and circulating blood cells in painters exposed to ethylene glycol ethers.

In a previous cross-sectional survey, up to 15% of shipyard painters were found to have mild anemia or granulocytopenia, mostly acquired since employment. Environmental studies had suggested a possible etiologic role for ethylene glycol ethers, solvents to which the men were heavily exposed and which have established myelotoxic potential. To exclude alternative hypotheses, examine possible common patterns of injury, and identify potential risk factors and markers for such an effect, the affected painters were further studied. The painters were matched with two groups of controls: exposed painters without evidence of hematologic abnormality on the previous survey and unexposed controls. Altogether 25 subjects were studied by histopathologic examination of bone marrow, cytogenetic studies of marrow cells, and peripheral lymphocytes and peripheral red cell studies of membrane and metabolic function. Except for an unexpected finding of a race-associated effect on marrow histology, insignificant differences were seen among the groups in terms of marrow morphology and cellularity, stem cell growth kinetics, and marrow or peripheral cytogenetics. Two metabolic abnormalities of peripheral red cells related to exposure or clinical status of the subjects were found. Pyruvate kinase, an established marker of acquired myelodysplasia, was significantly depressed in the subjects with previously abnormal counts. Although reduced glutathione levels and holoenzyme activities of glutathione reductase (GSHR) did not differ among groups, exposed subjects had decreased saturation of GSHR with flavin adenine dinucleotide which could be restored in vitro, suggesting riboflavin deficiency or impaired riboflavin metabolism. Thus, although a unique pattern of bone marrow injury by histologic or genetic assay attributable to ethylene glycol ethers was not defined, biochemical effects of possible mechanistic importance were identified. The relevance of these findings as subclinical disease markers remains to be established.

Adult↗
PubMed2002

D-chiro-inositol--its functional role in insulin action and its deficit in insulin resistance.

In this review we discuss the biological significance of D-chiro-inositol, originally discovered as a component of a putative mediator of intracellular insulin action, where as a putative mediator, it accelerates the dephosphorylation of glycogen synthase and pyruvate dehydrogenase, rate limiting enzymes of non-oxidative and oxidative glucose disposal. Early studies demonstrated a linear relationship between its decreased urinary excretion and the degree of insulin resistance present. When tissue contents, including muscle, of type 2 diabetic subjects were assayed, they demonstrated a more general body deficiency. Administration of D-chiro-inositol to diabetic rats, Rhesus monkeys and now to humans accelerated glucose disposal and sensitized insulin action. A defect in vivo in the epimerization of myo-inositol to chiro-inositol in insulin sensitive tissues of the GK type 2 diabetic rat has been elucidated. Thus, administered D-chiro-inositol may act to bypass a defective normal epimerization of myo-inositol to D-chiro-inositol associated with insulin resistance and act to at least partially restore insulin sensitivity and glucose disposal.

Animals↗
PubMed1996

Tritrichomonas foetus: iron acquisition from lactoferrin and transferrin.

Acquisition of iron from lactoferrin and transferrin by a parasitic protozoon Tritrichomonas foetus has been studied in vitro. Specific, time-dependent, and saturable binding of iodinated ligands to the outer membrane of T. foetus at 4 degrees C was demonstrated for 125I-labeled lactoferrin only. About 1.7 x 10(5) binding sites of a single class with Kd approximately equal to 3.6 microM was estimated by means of Scatchard analysis. Internalization of the bound lactoferrin was observed at 37 degrees C. The cell-associated radioactivity after 30 min incubation of the parasite with 125I-lactoferrin at 37 degrees C was about 3.5-fold higher than the amount bound at 4 degrees C. The majority of internalized 125I-lactoferrin was released within 15 min of cell reincubation at 37 degrees C in the presence of a 100-fold excess of nonlabeled lactoferrin. Released lactoferrin displayed unchanged mobility on autoradiography. In contrast to lactoferrin, binding of 125I-transferrin was nonspecific and did not display saturable kinetics. The growth of T. foetus in iron-restricted media was stimulated by both lactoferrin and transferrin. The ability of the cells to remove and accumulate iron from both proteins was therefore examined using 59Fe-saturated lactoferrin and transferrin. It was found that trichomonads acquired a comparable amount of iron from both lactoferrin and transferrin during 60 min incubation at 37 degrees C (495 and 577 pmole Fe/mg of protein, respectively). The pH of the assay medium (PBS) decreased from pH 7.4 to 5.6 after incubation with trichomonads. At this pH, marked release of iron from transferrin (up to 47%) but not from lactoferrin (4%) was determined in cell-free media. These results indicate that T. foetus is able to utilize both lactoferrin and transferrin to cover its iron requirements. However, mechanisms of iron acquisition from these host proteins appear to be different. Specific binding and internalization of lactoferrin suggests the possible involvement of receptor-mediated endocytosis in the acquisition of lactoferrin-bound iron, while retrieval of iron from transferrin may depend on the extracellular release of iron from this ligand.

2,2'-Dipyridyl↗
PubMed2001

Loss of multiple hydrogenosomal proteins associated with organelle metabolism and high-level drug resistance in trichomonads.

Land, K. M., Clemens, D. L., and Johnson, P. J. 2001. Loss of multiple hydrogenosomal proteins associated with organelle metabolism and high-level drug resistance in trichomonads. Experimental Parasitology 97, 102-110. In trichomonads, metronidazole is activated to its cytotoxic form in a specialized energy-producing organelle called the hydrogenosome. Electron transport components in the organelle, pyruvate:ferredoxin oxidoreductase and ferredoxin, donate a single electron to the drug, converting it to a cytotoxic free radical. Previous biochemical analyses of enzyme activities of highly resistant strains of both Trichomonas vaginalis and Tritrichomonas foetus reveal undetectable activity for pyruvate:ferredoxin oxidoreductase and another hydrogenosomal enzyme, hydrogenase. We have chosen to analyze a highly drug-resistant strain of T. foetus and its parental drug-sensitive strain from which it was derived to study the molecular basis for these enzyme defects. Quantitation of pyruvate:ferredoxin oxidoreductase and ferredoxin levels in sensitive and resistant cells shows a marked reduction of these proteins in the resistant strain. RNA analysis reveals an approximately 60% reduction in pyruvate:ferredoxin oxidoreductase mRNA and 90-98% reduction in mRNA levels encoding hydrogenosomal proteins hydrogenase, ferredoxin, and malic enzyme. We have measured the levels of transcription of these genes and observed 60% reduction of pyruvate:ferredoxin oxidoreductase gene transcription and 85% reduction in malic enzyme gene transcription in the resistant strain. The reduction or absence of these organellar proteins is likely to reduce or eliminate the ability of the cell to activate the drug, giving rise to the highly resistant phenotype. Ultrastructural analysis of thin sections revealed that resistant cells are 20% smaller in size and hydrogenosomes in resistant cells are approximately one-third the size of those in the drug-sensitive parental strain. These data suggest that altered gene expression of multiple hydrogenosomal proteins results in the modification of the organelle and leads to drug resistance.

Animals↗
PubMed1998

The pyruvate:ferredoxin oxidoreductase enzyme is located in the plasma membrane and in a cytoplasmic structure in Entamoeba.

This work investigated the cellular location of the pyruvate:ferredoxin oxidoreductase (PFO) enzyme in Entamoeba. A 1.9 kb fragment located at the 3' end of the Ehpfo gene was cloned in the pRSETB vector and expressed. The recombinant peptide was purified and inoculated in rabbits. By Western blot assays the antibodies detected a single 130 kDa band in all E. histolytica strains tested and in E. moshkovskii. By immunofluorescence, the antibodies showed the presence of PFO in the plasma membrane and in a cytoplasmic structure that appeared as a ring or as a compact small body in E. histolytica strains. In E. invadens and E. moshkovskii (strains FIC and Laredo) PFO was located in the plasma membrane showing different fluorescence patterns. Immunofluorescence on E. histolytica synchronized cultures showed that the cytoplasmic structure appeared in 85, 60, 20 and 10% of the trophozoites in mitosis, G1, S and G2 phases, respectively. By in situ hybridization the Ehpfo gene was found in the nuclei and the trophozoites of the clone A, strain HM1:IMSS, differed in the Ehpfo gene content.

Animals↗
PubMed1993

Characterization of hydrogenosomes and their role in glucose metabolism of Neocallimastix sp. L2.

In the anaerobic fungus Neocallimastix sp. L2 fermentation of glucose proceeds via the Embden-Meyerhof-Parnas pathway. Enzyme activities leading to the formation of succinate, lactate, ethanol, and formate are associated with the cytoplasmic fraction. The enzymes 'malic enzyme,' NAD(P)H:ferredoxin oxidoreductase, pyruvate:ferredoxin oxidoreductase, hydrogenase, acetate:succinate CoA transferase and succinate thiokinase leading to the formation of H2,CO2, acetate, and ATP are localized in microbodies. Thus, these organelles are identified as hydrogenosomes. In addition, the microbodies contain the O2-scavenging enzymes NADH- and NADPH oxidase, while NAD(P)H peroxidase, catalase, or superoxide dismutase could not be detected. In cell-free extracts from zoospores of Neocallimastix sp. L2 the specific activities of hydrogenosomal enzymes as well as the quantities of these proteins are 2- to 6-fold higher than in mycelium extracts. These findings suggest that hydrogenosomes perform an important role--especially in zoospores--as H2-evolving, ATP-generating and O2-scavenging organelles.

Adenylate Kinase↗
PubMed1989

Purification and characterization of the pyruvate-ferredoxin oxidoreductase from Clostridium acetobutylicum.

The pyruvate-ferredoxin oxidoreductase from Clostridium acetobutylicum was purified to homogeneity and partially characterized. A 9.2-fold purification was achieved in a three step purification procedure: ammonium sulfate fractionation, chromatography on Phenyl Sepharose and on Procion Blue H-EGN12. The pure enzyme exhibited a specific activity of 25 U/mg of protein. Homogeneity of the pyruvate-ferredoxin oxidoreductase was confirmed by native polyacrylamide gel electrophoresis and sodium dodecylsulfate (SDS)-polyacrylamide gel electrophoresis. The molecular weight was determined to be 123,000/monomer. The subunit composition of the native enzyme could not be determined because of the instability of the pure enzyme. The pyruvate-ferredoxin oxidoreductase is sensitive to oxygen and dilution during purification. The dilution inactivation could be partially overcome by the addition of 300 microM coenzyme A or 50% ethyleneglycol. A thiamine pyrophosphate content of 0.39 mol per mol of enzyme monomer was found, the iron and sulfur content was 4.23 and 0.91, respectively. The pH-optimum was at pH 7.5 and the temperature optimum was at 60 degrees C. Kinetic constants were measured in the forward reaction. The apparent Km for pyruvate and coenzyme A were 322 microM and 3.7 microM, respectively. With 2-ketobutyrate the pyruvate-ferredoxin oxidoreductase showed 12.5% of the activity compared to pyruvate. No activity was found with 2-ketoglutarate. Ferredoxin from Clostridium pasteurianum could be used as physiological electron acceptor.

Chromatography, Ion Exchange↗
PubMed1996

Entamoeba histolytica: gene linkage groups and relevant features of its karyotype.

We identified some gene linkage groups in Entamoeba histolytica using a 4-M urea improved transversal alternating field electrophoresis (TAFE) method. Complex rosette-structured DNA molecules were found trapped along the gel lanes, explaining the fuzziness of the patterns. Using several episomal probes, including 16 S, 5.8 S, and 25 S ribosomal (r)Dna genes, an autonomous replication sequence (ARS), and EhVR1, we identified a complete ribosomal episome linkage group (CELG) at the 1.2-Mb position. Three other incomplete groups were found: IELG-1, formed by EhVR1, 16 S, 5.8 S, and 25 S genes; IELG-2 formed by EhVR1, 16 S and 25 S; and IELG-3 formed only by 5.8 S. Ehadh3, Ehpfo, and Ehredox genes migrated at the 1.8-Mb position, forming the non-ribosomal linkage group, NRLG-1.8, while the Ehenl-1 gene migrated at 1.6 Mb forming the NRLG-1.6 group. Ehhk was located at 1.2, 0.8, and 0.17 Mb in three different groups: NRLG-1.2, IELG-3-0.8, and NRLG-0.17. Putative lineal chromosomes were also identified using an heterologous telomeric probe. By in situ hybridization experiments, the rDNA and Ehhk genes were located in both nucleus and cytoplasm, while the Ehpfo and Ehredox genes were found mainly in the nucleus. We propose a model hypothezising that the 16 S and 25 S genes are in a linear molecule, duplicated in two inverted repeats, which may be looped out of the linear DNA to form an episome probably lacking or not the 5.8 S sequence, which could be added later by recombination.

Animals↗