Evaluation of Soybean Cultivars for Production in Meloidogyne arenaria Race 2-Infested Soil.

Field trials with 56 soybean cultivars and breeding lines from public and private sources were conducted from 1986 through 1988 at a site infested with Meloidogyne arenaria race 2. Differences (P < 0.05) among yields were found each year and yields were negatively correlated (P < 0.

Evaluation of Soybean Cultivars for Production in Meloidogyne incognita-infested Soil.

Significant (P < 0.05) differences among galling and yields of 41 soybean cultivars and breeding lines were found when they were produced at a site infested with Meloidogyne incognita during 3 years of investigation. Over a period of 6 years of testing, 13 cultivars were identified as having a suitably low susceptibility to warrant their production in M.

Galling and Yields of Soybean Cultivars Grown in Meloidogyne arenana-Infested Soil.

Field trials with 39 soybean cultivars and five breeding lines from public and private sources were conducted from 1982 through 1985 at sites infested with Meloidogyne arenaria. Nematode population densities and root-knot galling were measured for each soybean entry. All were efficient hosts for the nematode, and average juvenile numbers in the soil increased 5-50 x from planting to harvest.

On the nature of the stimulation of the lipoxygenase from rabbit reticulocytes by biological membranes.

The oxygenation of concentrated emulsions (about 260 microM) of arachidonic acid or linoleic acid catalyzed by the purified lipoxygenase from rabbit reticulocytes is strongly stimulated in the presence of low concentrations of beef heart submitochondrial particles or other membrane preparations. Maximal stimulation was observed at a proportion of about 5 mumoles polyenoic acid per mg of membrane protein. Whereas at a constant ratio of arachidonic acid and membranes the reaction rate obeyed the Michaelis-Menten kinetics with an apparent Km value of 75 microM for arachidonic acid, sigmoid kinetics was observed under conditions of constant concentration of membranes and, consequently, varying proportions of arachidonate and membranes.

The mechanism of inactivation of lipoxygenases by acetylenic fatty acids.

The inactivation of soybean lipoxygenase by 5,8,11,14-eicosatetraynoic acid was studied in detail. The inactivation was found to be time-dependent and irreversible. A kinetic scheme, based on the assumption of a rapid inactivation of the enzyme-product complex, yielded a Km value for 5,8,11,14-eicosatetraynoic acid of 1.

Haemoglobin potentiates the respiration-inhibitory action of lipoxygenases via its pseudolipohydroperoxidase activity.

The inhibition of the NADH oxidase and of the succinate-cytochrome c oxidoreductase activities of beef heart submitochondrial particles (ETP) induced by reticulocyte lipoxygenase is strongly potentiated by haemoglobin added simultaneously or subsequently to lipoxygenase. Half-maximal potentiation was observed with 0.9 microM haemoglobin.

Determination and characteristics of energy-dependent proteolysis in rabbit reticulocytes.

In reticulocytes exists an extensive and time-limited ATP-dependent proteolysis which has been measured by a new method. This enzyme system attacks exclusively the mitochondria during the maturation of reticulocytes. The proteolysis is inhibited by anaerobiosis and salicylhydroxamic acid which indicates that it is preceded by the attack of lipoxygenase.

The lipoxygenase of reticulocytes. Purification, characterization and biological dynamics of the lipoxygenase; its identity with the respiratory inhibitors of the reticulocyte.

A lipoxygenase has been purified from rabbit reticulocyte-rich anaemic blood cells. It possesses a molecular weight of 78 000 and an isoelectric point of 5.5 and contains 5% neutral sugars and two iron atoms per enzyme molecule.

[Selectivity of action of the lipoxygenase from rabbit reticulocytes on mitochondria and erythrocyte membranes].

Whereas the lipoxygenase from rabbit reticulocytes caused a large formation of malonyl dialdehyde (MDA) with rat liver mitochondria, erythrocyte ghosts were attacked only slightly independently of their type of preparation. The formation of MDA was not enhanced by release of spectrin-actin from the ghosts. The lipoxygenase did not give rise to hemolysis of intact erythrocytes.

[Action of respiratory inhibitors on the electron transport system of Escherichia coli].

Bacteria of two strains of Escherichia coli (Q13 and MRE 600) were disintegrated by aluminium oxide. The influence of the respiratory inhibitors RF (a protein from reticulocytes), carboxin, Dexon (fungicides), thenoylftrifluoroacetone (TTFA), rotenone, antimycin A, myristic acid and monolaurin was tested on the succinate oxidase and the NADH oxidase system, respectively, of the membrane preparation obtained in this way as well as on the NADH oxidase activity of the cytosol. Among the inhibitors listed, only TTFA (5mM) inhibited the succinate oxidase system and Dexon (10 miconr), monolaurin (100 micron) and myristic acid (100 micron) inhibited the NADH oxidase system of the membranes.

Degradation of mitochondria by cytosolic factors in reticulocytes.

The degradation process of mitochondria in rabbit reticulocytes proceeds predominately directly in the cytosol rather than in secondary lysosomes as judged by electronmicroscopy. At least five cytosolic protein factors are present in reticulocytes, which could be related to the degradation of mitochondria: the two inhibitory proteins of the respiratory chain RF and RC and three enzymes which cause a lysis of mitochondria in vitro (lipoxygenase, proteinase, phospholipase A). The properties of these factors are the subject of this paper.

[Chacterization of human reticulocytes: respiration, Pasteur effect, and electron microscopic findings on mitochondria].

On 5 blood samples of newborns, whose reticulocytes had been enriched by density gradient centrifugation, and on 25 blood samples of different reticulocytoses of man were determined: the extent of intra- and extramitochondrial respiration, coupling of the electron transfer with the oxidative phosphorylation and the electronmicroscopic appearance, and the number of mitochondria. The reticulocytes occurring in the flowing human blood are in general relatively stiff and are characterized by the following properties:--low respiration--low capacity of the respiratory chain enzymes--weakened Pasteur effect --varying proportion of intramitochondrial respiration and total respiration--decoupling of a major part of the intramitochondrial respiration--low number of mitochondria--qualitative changes of mitochondria. However, there are situations of erythropoiesis where immature reticulocytes are discharged in man (similar to the socalled "stress reticulocytes" of rabbits).

Some properties of the lipoxygenase from rabbit reticulocytes.

A lipoxygenase was enriched from the stoma-free supernatant of rabbit reticulocytes. The enzyme causes drastic deterioration of mitochondrial membranes. The release of matrix enzymes is paralleled by formation of products of lipid peroxidation.

[Action of the systemic fungicide dexon on several NADH dehydrogenases].

The fungicide dexon (p-dimethylaminobenzenediazosulfonate, Na-salt) inhibits the NADH oxidase activity of submitochondrial particles (ETP) from beef heart (semi-inhibition concentration 1.4 muM), while the succinate oxidase activity is unaffected. Measurements of the activity of several enzymatic partial reactions of the respiratory chain of ETP suggest that dexon acts directly on the flavine of NADH dehydrogenase.