Establishment, maintenance and description of cell lines from the tick Ixodes scapularis

Interest in tick-borne pathogens has been enhanced by the emergence of Lyme disease and, more recently, human and animal ehrlichioses. In order to facilitate investigations of the vector phase of tick-borne disease agents in vitro, several new cell lines derived from embryonated eggs of northern (IDE lines) and southern (ISE lines) populations of the tick Ixodes scapularis were developed. The establishment and characteristics of 4 IDE (IDE1, 2, 8, and 12) and 2 ISE (ISE5 and 18) lines were described. Primary cultures were initiated in L-15B medium at 31 C from a single egg mass each and established lines developed a morphologically distinct phenotype. Myoblasts were present during the first year after isolation in several lines as isolated clusters or sheets covering the whole flask. Cell line extracts resolved by isoelectric focusing were characterized for 3 isozymes (lactate dehydrogenase, malate dehydrogenase, and malic enzyme). The combined banding patterns allowed discrimination between Ixodes cell lines and a Rhipicephalus appendiculatus cell line. Two lines, i.e., ISE5 and ISE18, had unique isozyme bands. Chromosome numbers and morphology conformed to those described from tissue squashes of I. scapularis.

Identification of Leishmania isolates from a Lebanese population

We report the results of enzymatic patterns of isolates of Leishmania cultured from patients referred to Department of Dermatology of the American University of Beirut Medical Center in Lebanon. The results reveal that these Lebanese isolates are all very similar despite variable clinical presentations of the patients and differences in geographic origin. Leishmania donovani sensu lato is the dominant species present in the skin lesions observed; thus, clinical manifestations and/or geographic distribution cannot be used as reliable criteria for identifying Leishmania parasites from this geographic area. Enzyme data should be combined with these parameters before definitive identification can be made.

Hysteresis of cytosolic NADP-malic enzyme II from Trypanosoma cruzi

NADP-malic enzyme II, one of two isoenzymes of NADP-malic enzyme (EC 1.1.1.40) in Trypanosoma cruzi epimastigotes, presents hysteretic behavior that results in a kinetic lag in the reaction progress curve. The lag is affected by the malate, aspartate and oxaloacetate concentrations in the assay mixture. This dependence suggests that hysteresis is due to an association-dissociation process influenced by the binding of these ligands to the enzyme. The enzyme was separated from NADP-malic enzyme I and purified 43-fold from a cell homogenate by a procedure involving column chromatography on DEAE-Sephacel and Cibacron-blue Sepharose. The molecular mass of the highly purified enzyme was determined as 126 kDa.

Randomly amplified polymorphic DNA (RAPD) and isoenzyme analysis of Trypanosoma rangeli strains

Sixteen Trypanosoma rangeli strains were compared by isoenzyme and randomly amplified polymorphic DNA (RAPD) analysis. Eight strains were isolated from either Rhodnius prolixus or Homo sapiens from Honduras, Colombia and Venezuela. Another eight strains were isolated from either Panstrongylus megistus or the rodent Echimys dasythrix from the State of Santa Catarina, southern Brazil. All six T. rangeli strains isolated from P. megistus were co-infections with Trypanosoma cruzi, demonstrating an overlap of the sylvatic cycles of these parasites and that the accurate identification of species is of utmost importance. Both isoenzyme and RAPD analysis revealed two distinct groups of T. rangeli strains, one formed by the strains from Santa Catarina and the other, by the strains from Honduras, Colombia and Venezuela. With the five enzymes used, all the strains from Santa Catarina had identical profiles which overlapped with those of the other regions only in the pattern obtained with malic enzyme. Analysis of 138 RAPD bands by means of an unweighted pair group method analysis (UPGMA) phenogram using the Dice similarity coefficient allowed the separation of the two groups based on their divergence at a lower level of similarity than the phenon line. We show that the identification of T. cruzi and T. rangeli in naturally mixed infections is readily achieved by either RAPD or isoenzyme analysis.

Some enzymes of gluconeogenesis in various fractions of sarcocysts of Sarcocystis fusiformis of buffalo (Bubalus bubalis)

A biochemical study was conducted to assess the relative presence of some enzymes of gluconeogenesis in various fractions--the cyst wall, cyst fluid and zoites--of sarcocysts of Sarcocystis fusiformis obtained from the oesophageal muscles of naturally infected Indian water buffalo (Bubalus bubalis). The activities of fructose 1,6-diphosphatase and malic enzyme were beyond detectable limits. Phosphoenol pyruvate carboxykinase (PEPCK) activity was maximally present in the zoites, whereas glucose 6-phosphatase activity was highest in the cyst wall. PEPCK seemed to play a crucial role in carbon dioxide fixation metabolism.

Subregional and intracellular distribution of NADP-linked malic enzyme in human brain

High total activity (expressed as mumol/min/g of wet tissue or per milligram of DNA) and differential subregional distribution of NADP-linked malic enzyme was found in autopsy specimens of human brain. Striatum showed the highest activity of malic enzyme, which was two- to five-fold higher than that in other human organs tested. High activity was also found in frontal cortex, while the lowest activity of the enzyme in the central nervous system was found in cerebellum, substantia alba, and corpus callosum. In striatum, frontal cortex, pons, and cerebellum more than 80% of total malic enzyme activity was localized in the mitochondrial fraction, while in substantia alba and corpus callosum approximately 60% of the enzyme activity was present in the mitochondrial fraction. Relatively high specific activity of malic enzyme was found in a crude mitochondrial fraction isolated from various regions of human brain. The highest specific activity was found in the mitochondria isolated from striatum (more than 100 nmol/min/mg of mitochondrial protein); the lowest, but still high (approximately 32 nmol/min/mg of mitochondrial protein) was present in corpus callosum. These data and the different ratios of citrate synthase to mitochondrial malic enzyme activities found in different regions of brain suggest that human brain mitochondria, like the mitochondria isolated from other mammalian brains, are extremely heterogenous. A possible role of mitochondrial malic enzyme in human brain metabolism is discussed.

Cloning and analysis of the C4 photosynthetic NAD-dependent malic enzyme of amaranth mitochondria

In some C4 plant species, a mitochondrial NAD-dependent malic enzyme (EC 1.1.1.39) (NAD-ME) catalyzes the decarboxylation of 4 carbon malate in the bundle sheath cells, releasing CO2 for the Calvin cycle of photosynthesis. In amaranth, a dicotyledonous NAD-ME-type C4 plant, the photosynthetic NAD-ME purified as two subunits of 65 and 60 kDa, designated alpha and beta, respectively. Antiserum raised against the alpha subunit reacted only with the 65-kDa protein in immunoblot analysis. Immunogold electron microscopy using the alpha subunit antiserum demonstrated that this protein was localized specifically to the mitochondrial matrix of bundle sheath cells. The complete nucleotide sequence of a 2300-base pair alpha subunit cDNA clone showed that this gene encodes a protein that contains all of the motifs required for a complete and functional malic enzyme. The alpha subunit has significant similarity along its entire length to other known NAD- and NADP-dependent malic enzymes from plants, animals, and bacteria. The findings presented here provide new insights about the C4 photosynthetic NAD-ME and its evolutionary relationship to other forms of malic enzyme present in eukaryotic and prokaryotic organisms.

Characterization of Prevotella intermedia and Prevotella nigrescens isolates from periodontic and endodontic infections

The occurrence and surface properties of prevotella intermedia and P. nigrescens in healthy sites and in periodontic and endodontic infections were studied among 73 strains, tentatively identified as P. intermedia. Fifteen strains were from necrotic root canal infections, 41 were from periodontal samples, and 17 isolates were obtained from healthy gingival sites. Identification of isolates as either P. intermedia or P. nigrescens was based on differences in malate and glutamate dehydrogenase electrophoretic mobilities which allowed unambiguous separation of P. intermedia and P. nigrescens. The majority of strains from periodontal samples were P. intermedia (29 of 41 strains). In endodontic samples only 4 out of 15 isolates were P. intermedia, while all except 1 of 17 strains from healthy gingival sites were identified as P. nigrescens. SDS-PAGE of whole cell proteins revealed 31 and 38 kDa proteins in P. nigrescens which were not detected in P. intermedia. Surface biotinylation of cells, followed by Western blotting and detection by alkaline phosphatase conjugated extravidin, showed strong staining of the 31 kDa protein in P. nigrescens indicating that this protein is located on the surface of the cell. Corresponding staining was not seen in P. intermedia. Fimbria-like projections were observed using electron microscopy of negatively-stained cells of P. nigrescens. The results show that P. intermedia and P. nigrescens may have different site specificities and surface properties and thus emphasize the need for accurate identification of these two species for the evaluation of their role in the pathogenesis of oral infections.

Human urinary trypsin inhibitor, urinastatin, prevents pancreatic injuries induced by pancreaticobiliary duct obstruction with cerulein stimulation and systemic hypotension in the rat

OBJECTIVE

The protective effects of human urinary trypsin inhibitor against pancreatic injuries in multifactor-related experimental model of acute pancreatitis were evaluated.

DESIGN

Experimental study.

MATERIALS AND METHODS

Acute pancreatitis was induced by short-termed (1-hour) pancreatico-biliary duct obstruction with cerulein stimulation (30 minutes; 0.2 microgram/kg per hour) and systemic hypotension (30 minutes; 30% reduction of mean arterial pressure) in rats. In this model, the protective effects of UTI against pancreatic injuries were evaluated at a dose of 10,000 U/kg per hour.

RESULTS

In this model, significant increases in portal serum amylase, cathepsin B and malate dehydrogenase levels were observed as compared with the control rats. The redistribution of cathepsin B from the lysosomal to the zymogen fraction and activation of trypsinogen were also observed. Moreover, the increased lysosomal and mitochondrial fragility as well as impaired pancreatic adenylate energy metabolism were noted. The therapeutic administration of human urinary trypsin inhibitor had significant protective effects against these pancreatic injuries. Furthermore, the combined prophylactic and therapeutic administration of human urinary trypsin inhibitor had more significant protective effects than only therapeutic treatment.

CONCLUSIONS

These results suggest the importance of timing and of selecting a pertinent protease inhibitor, such as urinary trypsin inhibitor, in the treatment of pancreatitis.

[Evaluation of the malate dehydrogenase activity in deteriorated sunflower seeds]

Malate dehydrogenase (MDH) activity in sunflower (Helianthus annus L. cv. Peredovik) seeds stored at 65 degrees C and 90 degrees C for 1, 3, 5, 7, and 14 days was evaluated. This study was design to discern the usefulness of this viability test for deteriorated seeds. Differences in the resistance to the heat storage were detected between treatments as reflected by changes in the evolution of MDH activity. A decrease of MDH activity in both soluble and mitochondrial fractions was observed, which was more evident in seeds stored at high temperature. These differences are poorly correlated to viability as determined by tetrazolium staining, and should be related to integrity of cellular membranes as evidenced by differential MDH activity in soluble and mitochondrial fractions.

Metabolic capacity of muscle fibers from high-altitude natives

We evaluate the effects of chronic hypoxia on the metabolic phenotype of the muscle fiber types of humans. The subjects were three Quechua natives residing in the Peruvian Andes at an altitude greater than 3300 m, and three lowlanders from below 700 m. Biopsy specimens were obtained from the vastus lateralis muscles of volunteers. Muscle fibers were identified histochemically as type 1 (oxidative), 2a (oxidative-glycolytic) or 2b (glycolytic). The relative contribution of each fiber type to the total cross-sectional area of each biopsy sample was determined. In individual fibers, the activities of malate dehydrogenase (MDH, citric acid cycle), lactate dehydrogenase (LDH, glycolysis) and adenylokinase (high-energy phosphate) were quantified. The cross-sectional area of the muscle occupied by each fiber type is comparable between Quechuas and lowlanders. Type 1 fibers are the only fiber type to demonstrate statistically significant (P < or = 0.05) differences in enzyme activities between Quechaus and lowlanders. MDH activity is, on average, 19.6% less (P < or = 0.0001) and LDH activity 28.1% more (P < or = 0.0001) in the type 1 fibers of the Quechuas. Chronic hypoxia appears to produce a shift from oxidative to glycolytic metabolism in those fibers which are typically the most aerobic in human muscle.

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.

Subcellular action of estradiol-17 beta in a freshwater prawn Macrobrachium rosenbergii

Injections with different doses (0.1, 0.25, 0.5, 1.0, 2.0, and 4.0 micrograms/g) of estradiol-17 beta (E2), administered three days consecutively, showed a statistically significant increase in mitochondrial Na(+)-K(+)-ATPase, cytosolic malate dehydrogenase, and cytosolic glucose-6-phosphate dehydrogenase activities in a dose-dependent manner in the hepatopancreas of the freshwater prawn (Macrobrachium rosenbergii) on the 4th day of treatment compared to the control values. A lower dose of 0.05 microgram/g was without any effect on these enzyme activities. A uniform increase in the Mg(2+)-ATPase activity was observed after injections with 0.5, 1.0, and 2.0 micrograms/g of E2. Ergosterol, a nonsex steroid did not show any change in the malate dehydrogenase and glucose-6-phosphate dehydrogenase activities on which this compound was tested at a 2.0 micrograms/g dose, compared to the control values. Simultaneous injection of tamoxifen (0.5 microgram/g), an antiestrogenic compound, with E2 (2 micrograms/g) caused inhibition of the E2-induced rise in mitochondrial Na(+)-K(+)-ATPase and cytosolic NADP-linked malate dehydrogenase activities. Conversely, tamoxifen (0.5 and 1.0 microgram/g) behaved as an estrogen agonist to the response (increase) of Mg(2+)-ATPase and cytosolic glucose-6-phosphate dehydrogenase activities. Potentiation of the estrogen effect with tamoxifen (1.0 microgram/g) was observed in these enzyme activities when used simultaneously with E2 (2 micrograms/g). Use of cycloheximide (0.5 mg/liter), a protein synthesis blocker, inhibited the inhibited the E2 (2 micrograms/g)-induced increase in all the enzyme activities studied. The data show specific and prominent subcellular action of estrogen with an indication of its role in energy-dependent ion transport and metabolic activation in hepatopancreas of the freshwater prawn.

[Electrophoretic analysis of isoenzyme and protein patterns of Romanomermis yunanensis and R. culicivorax (Nematoda:Mermithidae)]

Isoenzyme electrophoretic patterns of lactate dehydrogenase (LDH), malate dehydrogenase (MDH), esterase (EST) and peroxidase (PO) of post-parasitic juveniles and adults of Romanomermis yunanensis and R. culicivorax were analysed by disc electrophoresis, respectively. The protein patterns of the two species of Romanomermis were compared by vertical slab SDS polyacrylamide gel electrophoresis. The results showed marked differences in isoenzyme patterns (number of bands and/or Rf) of LDH and MDH between the two species of Romanomermis, but the similar positions of isoenzyme bands denoted a certain genetic relationship between them. No band was found in the isoenzyme patterns of PO and EST. Distinct differences in protein pattern were observed between the two species of Romanomermis, but some common bands in pattern reflected the phylogenetic relationships of these species. The differences of isoenzyme and protein patterns observed in this study have provided the reason for identifying and differentiating the two species of Romanomermis at the molecular level.

Purification of cytosolic malic enzyme from bovine brain, generation of monoclonal antibodies, and immunocytochemical localization of the enzyme in glial cells of neural primary cultures

Cytosolic malic enzyme (EC 1.1.1.40) was purified from bovine brain 5,600-fold to a specific activity of 47 U/mg. The enzyme is a homotetramer with a subunit molecular mass of 60 kDa and an isoelectric point of 6.2. Mouse monoclonal antibodies raised against this enzyme were purified and shown to be monospecific, as indicated by immunoblotting. Immunocytochemical examination of rat astroglia-rich primary cultures at the light microscopic level revealed colocalization of cytosolic malic enzyme with the astroglial marker glial fibrillary acidic protein. Also, a colocalization with the oligodendroglial marker myelin basic protein was found. Neurons in rat neuron-rich primary cultures did not show positive staining. The data suggest that cytosolic malic enzyme is a glial enzyme and is lacking in neurons.

Skeletal growth after oral administration of demineralized bone matrix

Oral administration of bone extracts obtained from bovine demineralized bone matrix to rats has a direct effect on bone metabolism, affecting bone proportions and some markers of bone formation such as bone malate dehydrogenase, serum alkaline phosphatase and serum osteocalcin. Furthermore collagen deposition, bone protein synthesis and nucleic acids content were significantly increased by the treatment.

Changes in activities of lipogenic enzymes in adipose tissue and liver of growing goats1

The lipogenic capacity of omental adipose tissue and liver was measured in vitro from samples obtained at slaughter from 33 young male goats. The animals were slaughtered either on the day of weaning (d 0) or 2, 14, or 56 d after weaning. Ages at weaning were 4 wk (early weaning) or 6 or 8 wk (late weaning). Blood samples from the jugular vein were taken before slaughter to measure the concentrations of plasma glucose and nonesterified fatty acids. There was a 30% decrease in glucose concentration after weaning. Nonesterified fatty acid concentration increased fourfold between d 0 and 2 after weaning. By d 14 after weaning, nonesterified fatty acids returned to basal concentration. The lipoprotein lipase (LPL) activity of adipose tissue declined markedly (90%) on d 2 after weaning. Lipoprotein lipase activity returned to preweaning values by d 56 after weaning in those goats that had ad libitum access to feed. In adipose tissue, nicotinamide adenine dinucleotide phosphate (NADP)-malate dehydrogenase activity fell by only 17% by d 2 after weaning and to 63% by d 14 after weaning. Lipoprotein lipase activity was closely related to metabolizable energy intake the day before slaughter. Acetyl-coenzyme A carboxylase activity was low in adipose tissue and it increased only slightly by d 56 after weaning. The data indicated that LPL played a preponderant role in the restoration of lipid stores after weaning. High NADP-malate dehydrogenase activity together with a high concentration of plasma glucose by d 56 after weaning suggested that this enzyme activity could be enhanced by high glucose availability in goat kids. Activities of lipase, acetyl-coenzyme A carboxylase, NADP-malate dehydrogenase, and glucose-6-phosphate dehydrogenase in liver were essentially unaffected by weaning. The extent and rapidity of change of lipogenic enzymes of goat kids was much more pronounced in adipose tissue than in liver.

[Isoenzyme spectrum of lactate dehydrogenase, malate dehydrogenase, esterase and acid phosphatase of rat brain cells at different times after external 1 Gy gamma irradiation]

The influence of external single gamma-irradiation with a dose of 1 Gy on the isoenzyme composition of lactate dehydrogenase, malate dehydrogenase, esterase and acid phosphatase in the cytoplasm of rat brain cells has been investigated. Irradiation was shown to cause differently directed changes in the ratio of the isoenzymes under study at different times after exposure. The isoenzyme spectrum of lactate dehydrogenase and malate dehydrogenase was shown to be normalized on day 30 after irradiation, whereas the isoform composition of esterase and acid phosphatase was not stabilized at that time.

Isoenzyme analysis of Haemonchus contortus resistant or susceptible to ivermectin

Three different strains of Haemonchus contortus (susceptible to ivermectin, S-IVM; selected for resistance to ivermectin, R-IVM; a multiple resistant strain, i.e. resistant to benzimidazole and ivermectin, R-IVM/SA) were examined for isoenzyme variation by starch gel electrophoresis. Using stains for seven enzymes separated in five different buffer systems, no differences in the electrophoretic mobility could be detected between any of the strains. Results demonstrate a low level of enzyme variation in H. contortus and no differences in enzyme electrophoretic profile between IVM-sensitive and IVM-resistant parasites. Differences between the ivermectin-sensitive and both ivermectin-resistant strains were observed with the propionyl esterases and although some of the differences are probably associated with benzimidazole resistance, others are associated with resistance to ivermectin. The three strains of H. contortus are generally identical; however, differences between all strains of H. contortus and a strain of Dictyocaulus viviparus were detected.

The isoenzyme characteristics of Trypanosoma evansi and Trypanosoma equiperdum isolated from domestic stocks in China

Twelve stocks of Trypanosoma evansi and one of Trypanosoma equiperdum isolated from domestic animals in China were examined for 16 enzymes using cellulose acetate and thin-layer starch gel electrophoresis. Differences were seen between stocks in only two of the enzymes, MDH and ALAT. Three of the T. evansi stocks, isolated from buffalo, and the T. equiperdum stock had the unusual pattern MDH-3, while all the other Chinese stocks had the common MDH-1. Two other stocks of T. evansi and again the T. equiperdum, all from equines, showed a new pattern ALAT-14. Otherwise the Chinese stocks had the same enzyme profile as T. evansi from elsewhere.

Enzyme electrophoretic polymorphism differentiates invasive from non-invasive Chlamydia psittaci ruminant isolates

A group of 24 Chlamydia psittaci strains isolated from ruminants, belonging to serotype 1 and previously classified as invasive in a mouse model of virulence, was compared to a group of 10 non-invasive strains belonging to serotype 2 by using determination of glucose-6-phosphate and L-malate dehydrogenase zymotypes resulting of the infection of cells by these strains. The serotype 1 or invasive isolates represent a homogeneous group by sharing a unique zymotype which was not observed in the non-invasive strains. On the contrary, the serotype 2 or non-invasive isolates constitute a heterogeneous group in generating 2 different zymotypes. Zymotyping clearly distinguishes the ruminant strains from an avian C. psittaci and two C. trachomatis isolates studied for comparison. Our results suggest the usefulness of the studied molecular approach for chlamydiae typing. Furthermore, it can be used as marker of virulence within the C. psittaci strains isolated from ruminants.

Mitochondrial malate dehydrogenase and malic enzyme of a filarial worm Setaria digitata: some properties and effects of drugs and herbal extracts

Mitochondrial malate dehydrogenase (mMDH) and malic enzyme (mME) of a filarial worm Setaria digitata were studied. mMDH exhibited the highest activities in the oxidation and reduction reactions at pH 9.5 and pH 6.2, respectively, while mME did so in the malate decarboxylation reaction at pH 6.8. mME showed no detectable activity on the pyruvate carboxylation direction. The Km values for malate (1.7 mM) and oxaloacetate (0.17 mM) and the ratio of Vmax oxidation: Vmax reduction (2.73) tend to favor the oxaloacetate reduction by mMDH. mME showed a relatively high Km value of 8.3 mM, for malate decarboxylation. A drug, diethylcarbamazine citrate (DEC-C), did not change appreciably the activity of either mMDH or mME, while filarin (a drug of herbal origin) effectively inhibited mMDH. The leaf extracts of Ocimum sanctum, Lawsonia inermis and Calotropis gigantea and leaf and flower extracts of Azadirachta indica were, however, found to inhibit both mMDH and mME.

A rapid and efficient method for the screening of acid phosphatase 1 in young tomato seedlings, and for the identification of root-knot nematode species using miniaturized polyacrylamide gel electrophoresis

A relatively rapid and highly sensitive miniaturized polyacrylamide gel electrophoresis technique is described for the analysis of certain isozymes from single cotyledons of tomato seedlings and from single females of the root-know nematode (Meloidogyne spp.). Homogenates from single tomato cotyledons (7, 14, 21, and 28 days old) were electrophoresed and stained for acid phosphatase 1 (Aps 1) activity. Cotyledons from plants of all the above age groups showed good Aps 1 activity. Nondestructive screening for tomato Aps 1 is therefore feasible, using very small samples, from as young as 7-day-old tomato seedlings. This could be of important use in expediting root-knot nematode resistance (based on the Aps 1-linked resistance gene Mi) screening for breeding programs, or F1 testing for seed production purposes. In addition, the mini-polyacrylamide gel electrophoresis technique was useful for determination of the Aps 1 allelic contribution to the total enzyme activity. The system was also used to detect malate dehydrogenase and esterase isozyme activity from single adult females of the four common root-knot nematodes, Meloidogyne arenaria, M. hapla, M. incognita, and M. javanica, with equally good results, enabling species discrimination.

A new technique for the precise location of lactate and malate dehydrogenases in goat, boar and water buffalo spermatozoa using gel incubation film

Gel incubation film, which contained gelatin to prevent the diffusion of enzyme during chemical reaction and phenazine methosulfate to operate as a hydrogen acceptor between NADH and tetrazolium, was used and light microscopy revealed that lactate dehydrogenase was located in the head and tail of the spermatozoa as well as in the midpiece, whereas malate dehydrogenase was confined to the midpiece in spermatozoa of the animals examined. In goat spermatozoa, lactate dehydrogenase was associated mainly with the inner acrosomal membrane in the head, the mitochondrial matrix in the midpiece and with flagellar fibrils in the tail, whereas malate dehydrogenase was present only in the mitochondrial matrix.

An explanation of the achromatic bands produced by peroxidase isozymes in polyacrylamide electrophoresis gels stained for malate dehydrogenase

When plant tissue extracts are electrophoresed on polyacrylamide gels and the gels are stained for malate dehydrogenase by the standard NAD-dependent dehydrogenase reaction, terminating in the formation of reduced Nitroblue Tetrazolium (NBT), achromatic bands, in addition to the expected chromatic bands, are observed. The achromatic bands are seen when the staining conditions favor a generalized background staining of the gel and have been shown, in a previous study, to be caused by peroxidase isozymes [1]. The present study examined the mechanism by which peroxidase produced the achromatic bands using horseradish peroxidase (HRP). The generalized background staining resulted from the phenazine methosulfate (PMS)-mediated reduction of NBT. This reduction was enhanced by H2O2 and suppressed by HRP. Peroxidase apparently catalyzes the peroxidative oxidation of reduced PMS, which suppresses the generalized reduction of NBT in gel regions containing peroxidase isozymes producing the achromatic bands. In contrast, however, HRP also appears to catalyze the peroxidative oxidation of reduced NAD, but this reaction increases the reduction of NBT. The results are discussed in the context of the mechanisms proposed by others for the PMS-mediated reduction of NBT and for the peroxidase-catalyzed NADH-dependent formation of H2O2. This peroxidase-catalyzed reaction has been proposed for the plant peroxidases involved in lignification.