The effect of 2-methyl-4-chlorophenoxyacetic acid on the development ofHordeum distichum L. ovule

Application of a 1% aqueous solution of 2-methyl-4-chlorophenoxyacetic acid at the three-leaf phase brings about abnormalities in the development of barley ovule. The most typical abnormality is the complete or partial abortion of the embryonal sac, disturbances in the orientation of the embryonal sac (associated with the development of an integumental excrescence) and concrescences of two or more ovules. The abnormal ovules remain mostly unfertilized, which can have a negative influence on the crop.     

The effect of humus substances on the level of free amino acids in wheat plants

The presence of potassium humate (commercial sample of Humussäure Riedel-de Haën A. G., Seelze-Hannover) in distilled water led to an increase in the content of alanine, aspartic and glutamic acid in the overground parts of wheat plants as compared with the content of these substances in control plants grown in distilled water. In plants cultivated on nutrient solutions a higher level of alanine and glutamic acid and a considerably lower level of amides was found than in plants grown in distilled water and in water with humate. Generally the content of amino acids was higher in the overground parts than in the roots after a cultivation period of one week as well as of 14 day. In the overground parts of 1 days old plants the level of aspartic acid, asparagine and alanine was found to be higher and that of glutamine lower than in seven days old plants. In the roots of the examined plants a decrease of the amino acid content accurred almost in all cases after a cultivation period of 14 days as compared to one of 7 days.     

The effect of 2:4-dinitro-phenol on phosphorus transformations during humus decomposition

Summary The use of 2 : 4-dinitrophenol (DNP) in soil-phosphorus transformation studies revealed the presence of two broad groups of micro-organisms. One of these utilised only soil inorganic phosphate while the other derived its phosphorus solely through the mineralisation of soil organic phosphorus in spite of the presence of inorganic phosphate. The implications of this behaviour are briefly discussed.     

The effect of glycine,humus substances and sucrose on the growth of tomato rootsin vitro

The effect of glycine on the growth of isolated tomato roots in White’s nutrient solution was studied. It is obvious that the root tips grow better in the medium without glycine, because increasing rates of glycine produce inhibition. The growth of root explantates in nutrient media indicates a high synthetic ability of isolated roots. Optimal concentrations of humus acids in White’s nutrient solution without glycine and with glycine stimulate the growth of root explantates. It cannot be decided which of the two substances affects the root directly and which acts as a chelating agent in the medium. The effect of glycine varied, depending on the origin of sucrose used. It appears that in media containing beet sucrose, glycine is unsuitable but in media containing cane sucrose it is necessary.     

Share of carbohydrates in the humus substances composition

The effect of different concentrations of hydrochloric acid on the qualitative an quantitative content of carbohydrates in humus fraction hydrolyzates was investigated. Three humic acid preparations were subjected to the usual procedure for obtaining fractions of humic and hymatomelanic acids. The carbohydrate content of the hydrolyzates was determined after their Chromatographic separation on Whatman 1, using the Partridge system and detection with acid anilin phtalate. The results showed that the qualitative carbohydrate content in the hydrolyzates of most humus fractions of samples used was identical. With increasing acid concentrations the amount of hydrolyzable carbohydrates usually increased, the total amount of carbohydrate in the hydrolyzate not exceeding 4% . The difference in the carbohydrate content as between hydrolysis with 0-9N and 5-3N HC1 was sometimes fourfold. A higher content of hexoses than of pentoses was generally found.     

The toxic effect of dermotrophic substances in tests in vitro

In the model system of tissue culture, the effect of dermatotrophic substances, such as the tenzides and conservatory substances, was tested. The cytotoxic effect of the substances was evaluated according to the vitality of the cells and the lactate dehydrogenase (LDH) activity in the suspension culture of human lymphocytes and further according to the migration inhibition of cells from the animal spleen fragments (SF). The cells obtained from rabbits, guinea pigs, mice and man were used. The highest correlation between the concentration of the substance in the cultivation medium and its toxic effect in the culture has been proved in the tests of LDH activity from the supernatant of the human peripheral lymphocytes culture and further in the migration inhibition test from rabbit SF. Both the tests are in mutual correlation. The determination of LDH activity represents a sensitive marker of the cell damage, the least sensitive is the estimation of the cell vitality. It has been proved that the system of suspension culture of human peripheral lymphocytes and the migration inhibition test from rabbit SF is suitable for the screening determination of the effect of dermatotrophic substances. The system of tissue culture compared to classical tests of skin irritation performed in vivo secures overall objectivity in evaluating the results and the possibility of making a number of parallels without any ethical limits.     

Radiosensitizing and toxic effect of metronidazole and its ortho-isomer 1-(2-hydroxyethyl)-2-methyl-4-nitroimidazole on Escherichia coli B/r cells

A study was made of the effect of metronidazole and isometronidazole on the survival rate of irradiated and nonirradiated E. coli B/r cells. These substances had similar radiosensitizing activity with regard to anoxic cells and did not sensitize cells irradiated in the air. At the same time, isometronidazole was found to be less toxic than metronidazole.     

The effect of 2-(4-methyl-1-piperazinylmethyl) acrylophenone dihydrochloride on the alkylation of tubulin

2-(4-Methyl-1-piperazinylmethyl) acrylophenone dihydrochloride (MPMAP) is a novel inhibitor of microtubule assembly in vitro and in vivo whose molecular mechanism of action has not been investigated (M. L. Mallevais, A. Delacourte, I. Lesieur, D. Lesieur, M. Cazin, C. Brunet, and M. Luyckx (1984) Biochimie 66, 477-482). We have examined the effect of MPMAP on the alkylation of tubulin by iodo[14C]acetamide and N,N'-ethylenebis(iodoacetamide) (EBI). MPMAP is a very potent inhibitor of tubulin alkylation by iodo[14C]acetamide. MPMAP gives half-maximal inhibition at a concentration of 15 microM. MPMAP also inhibits the alkylation of denatured tubulin and of aldolase, implying that it reacts strongly with sulfhydryl groups. MPMAP does not, however, interfere with formation by EBI of a crosslink between cysteines 239 and 354 in the beta subunit of tubulin, suggesting that these sulfhydryls are located in a cleft in the tubulin molecule.     

The influence of humus acid on the respiration of plant roots

Biologia Plantarum - Humus acid (Humussäure Riedel de Haen AG. Seelze Hannover) in 0·01% concentration increases the respiration intensity of plant roots grown in water cultures both as...     

Enhancing effect of saccharides on the mutagenicity of 2-chloro-4-methylthiobutanoic acid

The mutagenicity of 2-chloro-4-methylthiobutanoic acid (CMBA), a nitrite-treated Sanma fish mutagen, in Salmonella typhimurium TA100 was enhanced by addition of D-glucose during the CMBA-treatment. Several other monosaccharides also enhanced the mutagenicity of CMBA, and the order of the enhancing potency was found to be D-mannose, D-glucose>D-fructose, D-ribose, D-galactose. A disaccharide, maltose, showed only little enhancement. No enhancement was found with L-glucose. We investigated whether saccharides affect uptake of [methyl-14C]CMBA into S. typhimurium TA100. Saccharides which enhanced CMBA-induced mutagenesis increased the uptake. L-Glucose did not enhance the uptake. There was good correlation between the enhanced mutagenesis and increased radioactivity in Salmonella, suggesting that the enhancing effect of monosaccharide on the CMBA-induced mutagenesis results from the enhanced uptake of the mutagen into bacteria.     

Influence of physiologically active substances of the soil humus on the activity of glucose-6-phosphate-dehydrogenase in pea (Pisum sativum L.) roots

The influence of phenolic and humic acids on the activity of glucose-6-phosphate-dehydrogenase in the roots of pea under aseptic conditions has been investigated. It seems clear that vanillic and protocatechuic acids inhibit the enzyme activity in the excised roots of pea, but their dry weight increases in relation to the control. Gallic acid stimulates the G-6-PD activity in the roots of whole plants. The humic acids influence neither the enzyme activity nor the dry weight of pea seedlings after short-term treatment.