Potential application of urea-derived herbicides as cytokinins in plant tissue culture.

Various urea-derived herbicides and different cytokinin analogues were used to determine their effects on callusing response and shoot regenerating capacity of alfalfa (Medicago sativa L.) and Coleus (Coleus forskohlii Briq.). The herbicides monuron and diuron evoked profuse callusing response from Coleus leaf segments and alfalfa petiole explants on Murashige and Skoog medium. Shoot regeneration by monuron (2.0 mg/l) showed a maximum of 3 multiple shoots both in alfalfa and Coleus with a frequency of 92% and 75%, respectively. Whereas diuron (0.5 mg/l) showed a high frequency of shoot regeneration (89%)with a mean number of 5 shoots in alfalfa, in C.forskohlii, the frequency of regeneration was 90%with a mean number of 6 shoots. Diuron with two chloride groups in the phenyl ring showed significantly higher cytokinin-like activity than single chloride substitution monuron. This study demonstrates the potential use of monuron and diuron as cytokinins in plant tissue culture.

Amylase induction during seed germination in isoproturon susceptible and resistant biotypes of Phalaris minor Retz.

Isoproturon resistant biotype of P. minor germinates early, shows higher germination percentage and faster rate of growth as compared to the susceptible biotype. Higher amylase activity is observed in the initial hours of imbibition in the resistant biotype. In the susceptible biotype it is activated at a much later stage.

Expresión de receptores a factor de crecimiento insulínico tipo I, c-fos y PCNA en un tumor mamario experimental / Expression to an insulin growth factor type I receptor, c-fos and Nuclear Antigen of cellular proliferatium in an experimental mammary tumor

Las terapias oncológicas conllevan generalmente efectos secundarios indeseados por lo que el mejor conocimiento de los mecanismos regulatorios del desarrollo y crecimiento tumoral puede abrir el camino a enfoques terapeúticos más adecuados. El objetivo de éste trabajo fue profundizar el estudio de la implicancia de factores que regulan el crecimiento del cáncer mamario empleando un modelo experimental químicamente inducido en rata, el que presenta similitudes con el cáncer mamario humano principalmente en lo que respecta a la regulación hormonal de su crecimiento. El tumor mamario fue inducido químicamente en ratas normales y diabéticas. Se analizó la expresión de receptores a factor de crecimiento insulínico tipo I (RIGF-I), el que forma parte de un sistema formado por factores de crecimiento, sus receptores y proteínas transportadas; éste sistema se encuentra alterado en pacientes con diabetes mellitus no dependiente de insulina. También se analizó la expresión de las proteínas c-FOS y PCNA (antígeno nuclear de proliferación celular), ambas relacionadas con la proliferación celular. Los resultados experimentales mostraron significativas diferencias en los tumores mamarios desarrollados: los de las ratas diabéticas presentaron mayor período de latencia (p<0,001), menor número de tumores desarrollados por rata (p<0,02) y una velocidad de crecimiento menor (p<0,05) con respecto a los tumores desarrollados en ratas normales. Asimismo, mostraron un patrón histológico de marcada benignidad, en contraste con los adenocarcinomas malignos ductales desarrollados en los animales normales. La expresión de las proteínas c-FOS y PCNA detectada por métodos inmunohistoquímicos fue significativamente menor en los tumores de las ratas diabéticas que en ratas normales. En cuanto a la expresión de RIGF-I, los resultados indicaron que la misma estaría regulada por las hormonas esteroides en animales diabéticos y normales. El trabajo permitió analizar experimentalmente la interrelación entre factores de crecimiento insulínicos y hormonas esteroides en el desarrollo y crecimiento tumoral mamario, particularmente cuando están presentes la patología mamaria y la diabetes

Effect of isoproturon on male reproductive system: clinical, histological and histoenzyonological studies in rats.

Isoproturon, a nonhalogenated substituted phenylurea herbicide, was evaluated for its cumulative toxic effects on testicular histomorphology., steroid hormone biosynthesis-related enzymes, spermatogenesis and sperm cells in adult albino rats. The compound, suspended in refined groundnut oil, was administered (po) to rats for 10 weeks @ 0,200, 400 and 800 mg/kg/day for 6 days/week. Isoproturon, at 800 mg/kg dose, decreased epididymal sperm count and percentage of motile sperms and increased the percentage of morphologically abnormal sperm cells. At the same dose, diameter of seminiferous tubules was reduced, number of tubules per microscopic field was increased and the percentage of tubules with evidence of spermatogenesis decreased. However, the percentage of damaged tubules was increased with 400 and 800 mg/kg doses. Histoenzymological observations revealed dose-related reduction in the activities of glucose-6-phosphate dehydrogenase and delta 5-3 beta-hydroxy steroid dehydrogenase. Activity of 17 beta-hydroxy steroid dehydrogenase was not affected appreciably. Overall findings suggest that isoproturon, at high dose, impairs androgen biosynthetic process, affects spermatogenesis and induces maturational anomalies of sperm cells in rat.

Subacute toxicity of urea herbicide, isoproturon, in male rats.

Isoproturon, a substituted phenylurea herbicide, was evaluated for its cumulative toxic effect on growth, organ weight and histomorphology of different organs in adult male rats. The compound (200, 400 and 800 mg/kg/day for 6 days/week), suspended in refined groundnut oil, was administered to rats p.o. for 7 and 10 weeks. There were no definite signs and symptoms of toxicity in treated rats but the herbicide significantly decreased the weekly body weight of rats at 800 mg/kg dose. Isoproturon, in all the three doses, increased the weight of liver in a dose-dependent manner. At 800 mg/kg dose, isoproturon increased the weight of kidney and heart, and decreased the weight of epididymis. Histopathological alterations in the organs were dose-dependent. Salient microscopic changes induced by isoproturon were hepatocellular degenerative changes and focal necrosis in liver, glomerular and tubular degeneration in kidney and haemosiderosis in spleen. Testis showed degeneration and desquamation of cells of germinal layers. Tubular lumens of testis and epididymis exhibited reduced number of spermatids and spermatozoa, respectively, indicating retardation of spermatogenesis.

Neurotoxicity of isoproturon, a substituted phenylurea herbicide, in mice.

Effects of single oral administration of isoproturon (0.5, 1.0 and 2.0 g/kg) on CNS of male mice were studied. At higher doses, spontaneous motor activity (SMA) and forced locomotor activity (FLA) were reduced. Reduction of SMA and FLA was lesser than the reference drug-chlorpromazine hydrochloride (Ch. HCl; 15 mg/kg). Isoproturon, at all doses, potentiated both pentobarbital and barbital-induced sleeping time. At higher doses, potentiation of pentobarbital-induced hypnosis was comparable to Ch.HCl but isoproturon was more effective in inducing hypnosis with barbital. Isoproturon could not protect mice against amphetamine-induced aggregation toxicity. Isoproturon exhibited anticonvulsant activity against both supramaximal electroshock seizures and pentylenetetrazol-induced convulsions. It had no anticonvulsant activity against strychnine but only caused delay in onset of and protection from mortality. At higher doses, anticonvulsant action of isoproturon was comparable to diphenylhydantoin (50 mg/kg) and phenobarbital sodium (100 mg/kg). The study reveals that isoproturon has distinct inhibitory effect on central motor performance and sedative action on CNS. And also it has anticonvulsive and protective actions.

Fetotoxic and teratogenic potential of substituted phenylurea herbicide, isoproturon, in rats.

Effect of isoproturon (0.225, 0.45 and 0.90 g/kg/day) administered (po) from day 6 through 15 of gestation was studied on pregnant rats and their offsprings. There were no distinct clinical signs other than dose-related depression and drowsiness of pregnant rats. None of the animals died due to toxicity of isoproturon. At higher doses, decreased maternal body weight was observed during the advanced stage of pregnancy. The litter size, fetal weight and crown-rump and transumbilical lengths were decreased. There was increase in fetal resorption frequency and the number of fetuses with stunted growth. The compound had no effect on fetal sex ratio. No major visceral and skeletal malformations were observed. The study indicates fetotoxic potential of the compound.

Genotoxic effect of isoproturon (herbicide) as revealed by three mammalian in vivo mutagenic bioassays.

Genotoxic effect of isoproturon was assessed by employing in vivo chromosomal aberration, micronucleus and sperm-shape abnormality assays. A significant dose-responsive mutagenic effect was observed in chromosome aberration and sperm-shape abnormality tests whereas in micronucleus assay the effect was significant only at the highest dose (200 mg/kg). Only the result for the chronic dose and the two different fixation times (6 and 48 hr) were not statistically significant. The results indicate the genotoxic property of isoproturon in mammalian in vivo test system.