Effect of alfa-difluormethylornithine on Anastrepha fraterculus (Diptera, Tephritidae) ovary size / Efeito da alfa-difluorometilornitina nas dimensões dos ovários em Anastrepha fraterculus (Diptera, Tephritidae)

Ovarian sizes (length and width) were measured in young females of Anastrepha fraterculus (Wiedemann) (Diptera, Tephritidae) subjected or not to the inhibitor α -difluormethylornithine (α -DFMO). The most effective concentration of α -DMFO used was 50 mM and the ovarian measurements (length and width) of the treated females were smaller than those of females not treated with α -DMFO. These data may suggest some relationship between ornithine decarboxylase (ODC) and sexual maturation in A. fraterculus.

As dimensões dos ovários (comprimento e largura) foram mensuradas em fêmeas jovens da Anastrepha fraterculus (Wiedemann) (Diptera, Tephritidae) submetidas ou não ao inibidor α -difluormetilornitina (α -DFMO). A concentração mais efetiva de α -DMFO utilizada foi 50 mM e as medidas (comprimento e largura) das fêmeas tratadas com o inibidor foram menores que as fêmeas não tratadas com inibidor α -DMFO. Estes dados podem sugerir uma relação entre ornitina descarboxilase (ODC) e maturação sexual em A. fraterculus.

Fluid regulation and A.D.H. in rat oestrus cycle; the effect of difluoromethyl ornithine [demo] and oestradiol

Plasma ADH concentration have been shown to fluctuate during the oestrus cycle of the rat and following ovariectomy. Oestradiol is also known to participate in the regulation of fluid and electrolyte balance. To determine how these variations in ADH and oestradiol concentrations are related to fluid balance, studies have been carried out in the overiectomized female rats injected subcutaneously daily with oestradiol benzoate [50 [micro]g/rat] and specific inhibitor of ornithine decarboxylase [ODC]; difuormethylorithine [DEMO 20 mg/100 g.b.w] for 7 days. The animals were housed in individual metabolism cages under 12 hr dark regimen with free excess to food and water. Urine samples to determine volume were obtained and food and water intake recorded at 8:00-9:00 and 17:00-18:00 hr. Plasma samples for determination of ADH levels by radioimmunoassay were taken. In DFMO and cestradiol benzoate treated rats, food and water intake were reduced during both dark and light periods compared with vehicle treated rats. But more urine output was observed in these animals. The result of this study indicate decreased water retention in the drug treated animals as compared to the controls. The observations of this study have shown that the underlying cause of fluid retention in the cycling rat during pro-oestrus may the oestradiol dependent elevation of the ADH levels. Furthermore, this increase in ODC activity in the hypothalamic neurons is part of mechanism underlying the oestradiol induced ADH release

Fluid balance: changes in cycling rats treated with difluoro-methyl-ornithine [DFMO] during the pro-oestrus.

Plasma vesopressin levels have been shown to fluctuate through out the rat oestrus cycle and following ovariectomy. To determine how these fluctuations in vesopressin are related to fluid regulations during the rat oestrus cycle. Studies have been carried out in cycling females rats using a specific inhibitor of Ornithine Decarboxylase [ODC], Di-fluoro-methyl Ornithine [DFMO 20 mg/100g body weight], the animals were housed in individual metabolism cages under 12 hours light/12 hour dark regimen with free access to food and water. Urine samples were collected to determine the osmolality and sodium concentration at 8.00 and 17.00-18.00 hours. The results of this study indicate a significant decrease in urine osmolality and sodium retention in the cycling pro-oestrus rats treated with DFMO as compared to the controls. The result of this study indicates that cause of fluid retention in the cycling rats during pro-oestrus may be the oestradiol dependent increased levels of vesopressin and the increase in the ODC activity in the Magno-cellular neurons is the part of mechanism underlying the oestradiol induced Vesopressin release

Control of zoopathogenic fungi in vitro by polyamine biosynthesis inhibitors.

Effect of inhibitors of polyamine (PA) biosynthesis, alpha-difluoromethylornithine (DFMO), methylglyoxal bis (guanylhydrazone)--MGBG and bis (cyclohexylammonium) sulphate (BCHA) on mycelial growth of three clinically important fungi-Trichophyton mentagrophytes, Microsporum gypseum and Aspergillus flavus was examined in vitro. All inhibitors at concentrations 1 to 50 mM produced greater inhibition of mycelial growth in all fungi tested in a dose-dependent manner. MGBG was the most effective inhibitor, and T. mentagrophytes was the most sensitive fungus to all inhibitors followed by M. gypseum and A. flavus. The results suggested that control of fungal diseases in animals and human beings with specific inhibitors of PA biosynthesis is possible.

Action of DL-alpha-difluoromethyl ornithine on Acanthamoeba culbertsoni.

The multiplication of A. culbertsoni in the peptone medium was not inhibited by 10-20 mM concentration of alpha-difluoromethyl ornithine (DMFO) while a partial and transient inhibition of cell multiplication was observed by 10-20 mM DFMO in proteose peptone, yeast extract, glucose (PYG) medium. Ornithine decarboxylase (ODC) activity in the cells and cell free extracts was strongly inhibited by DFMO, excluding enzyme refractoriness and impermeability of cells for DFMO as the possible causes of DFMO resistance. The presence of polyamines in the peptone and PYG media as well as uptake of polyamines by the amoebae has been demonstrated. The growth and multiplication of A. culbertsoni in chemically defined medium was not affected by 1-5 mM DFMO while 10-20 mM DMFO yielded partial inhibition. A lowering of diaminopropane levels and enhancement of spermidine levels was observed in DFMO inhibited cells and level of ODC was drastically reduced in the inhibited cultures. Uptake of polyamines from the growth media may partly account for DFMO resistance of A. culbertsoni. Alternative mechanisms for DFMO resistance are indicated.

Insecticidal activity of inhibitors of polyamine biosynthesis on Spodoptera litura F. larvae.

The inhibitors of polyamine (PA) biosynthesis such as alpha-difluoromethylornithine (DFMO), methylglyoxal bis (guanylhydrazone) (MGBG) and bis (cyclohexylammonium) sulphate (BCHA) have been used to protect crop plants from pathogenic fungi. In this communication the insecticidal activity of these inhibitors on tobacco caterpillar, S. litura has been reported. All the inhibitors exhibited insecticidal activity; MGBG being more effective than others. The results suggest, for the first time, a possible avenue for the control of insect pests by specific inhibition of insect PA biosynthesis.