A preliminary assessment of possible mutagenicity of betel nut and ingredients of the betel quid when administered alone or in combinations to larvae of Drosophila melanogaster.

The "carcinogenic" betel nut and constituents of betel quid were tested for possible mutagenicity in Drosophila. The test compounds were administered either alone or in combinations by larval feeding. The data on sex-chromosome loss, sex-linked recessive lethals and autosomal translocations suggest lack of mutagenicity.     

Formation of vitamin A in a freshwater fish. Isolation of retinoic acid.

The intestines of freshly caught Saccobranchus fossilis (a freshwater fish that contains dehydroretinol) became free from carotenoids and from vitamin A when the fish were starved for about 20 days. When beta-carotene was administered to such fish, retinoic acid could be isolated from the intestines after approx. 4h. When lutein was administered to such fish, dehydroretinol and 3-hydroxyretinol could be isolated from the intestines after approx. 5h.     

Urease activity and its Michaelis constant for soil systems

Summary Urea hydrolysis was measured in two separate sets of experiments. (1) Nine soil (0–15 cm) samples were treated with 200 g of urea-N g^–1 dry soil and incubated (at 37°C) at 50 per cent of the water holding capacity. Samples were periodically analysed for the remaining urea-N. The urease activity (time in hoursrequired to hydrolyse half the applied urea-N) was determined to be 5.8 to 15.2 hours in the various soils, which appeared to associate principally with the organic carbon content of the soils (r=–0.80^**). (2) Three soils were treated with 25 to 2000 g urea-N g^–1 dry soil amounting to 0.9 to 72.0 mM urea in 11 soil: solution. The system was buffered at pH 7.2 and agitated for 5h when the remaining urea-N was determined. The values of Km and Vmax were computed by two methods (i) from the integrated form of the Michaelis-Menten equation based on the results of the first study, and (ii) from the Michaelis-Menton equation based on urea hydrolysis in the second study. The integrated method appeared to be more suitable for enzyme kinetic studies in soil systems where the Km and V_max values bore close relationship (r=–0.88^**).     

Effect of temperature onin vitro pollen germination in pigeonpea

Pollen of pigeonpea(Cajanus cajan (L.) Millsp.) cultivars H-77-216 and ICPL-151 were cultivatedin vitro at six different temperatures (12, 17, 22, 27, 32, 37 °C). Pollen of cv. H-77-216 started to germinate at 17 °C whereas the pollen of cv. ICPL-151 at 22 °C, the optimal temperatures were 22 and 27 °C, respectively. Pollen germination at different temperatures was found to be positively correlated with the tube length. Per cent pollen bursting increased with rising temperature. The indeterminate cv. H-77-216 showed a wide range of suitable temperatures (17 – 27 °C) for pollen germination while the determinate cv. ICPL-151 had optimum at 27 °C     

Action of some retinol derivatives and their provitamins on microsome-catalyzed formation of benzo[a]pyrene-DNA adduct

Several vitamin A compounds have been tested for their ability to suppress formation of DNA adduct by the carcinogen benzo[a]pyrene (B[a]P) in an in vitro reaction catalyzed by rat liver microsomes. Retinol, retinal, 3-dehydroretinol and 3-hydroxyretinol were found to be effective inhibitors of adduct formation. Certain carotenoids that are precursors of these retinoids also displayed considerable inhibitory capacity. Carotenoids and the 3-substituted retinoids appeared to modulate the DNA adduct formation exclusively through their action on microsomal enzymes, since an effective inhibition in each case was observed on the formation of B[a]P-7,8-diol, a proximate carcinogenic metabolite of B[a]P. Unsubstituted retinoids, on the other hand, had marginal effect on enzymes but were found effective in accelerating inactivation of B[a]P-7,8-diol-9,10-epoxide, the ultimate carcinogenic metabolite that binds to DNA.     

Amylases during different stages of seed development in wheat

The β-Amylase activity was high in seeds of pre-Milk and milk stages but low in seeds of half seed and dough stages and very low at fully ripe stage of seed development. Zymogen (latent β-Amylase) was absent in half seed stage but appeared at pre-Milk stage. The content of zymogen increased progressively with advance in ripening time. No α-Amylase activity was detected at any stages of seed development in wheat.     

The broad spectrum antiviral agent ribavirin inhibits capping of mRNA.

Ribavirin (1-β-D-ribofuranosyl-1,2,4-triazole-3-carboxamide) is a broad spectrum antiviral substance active against a wide range of both DNA and RNA viruses. It is, however, virtually inactive against polio virus. Its pharmacological mechanism of action was obscure. A possible common target for a chemotherapeutic agent in both DNA and RNA viruses is the “capping” reaction of mRNAs which $\text{inter}\text{alia}$ involves the formation of a guanine pyrophosphate structure at the 5′ terminus by mRNA guanylyl transferase. We have observed that Ribavirin triphosphate is a potent competitive inhibitor of the capping guanylation of viral mRNA. This finding could account for the antiviral potency of the drug against both DNA and RNA viruses and its ineffectiveness against a virus in which the mRNAs derived from them are not capped.     

Uterine and placental 5-HT profile in different gestational period of albino rats

Possible role of 5-HT in pregnancy was investigated in albino rats by biological estimation of uterine and placental 5-HT contents in different periods of gestation in normal and drug treated rats. Uterine 5-HT level increased steadily from day-1 of gestation to reach the peak on day-7; thereafter, the level continued to decline throughout the period till day-20 when 5-HT level was lowest. From day-20, a mild secondary rise started and remained persistent even after parturition. The results show that a critical level of 5-HT in early gestational period is necessary for conception. Manipulation of endogenous 5-HT do not influence duration of gestation.     

Bio-control activity of Purpureocillium lilacinum strains in managing root-knot disease of tomato caused by Meloidogyne incognita

The potential of 24 indigenous isolates of Purpureocillium lilacinum (Paecilomyces lilacinus) (Thom) Samson collected from different agro-climatic zones of India was investigated against the root-knot nematode, Meloidogyne incognita. The studies were conducted in vitro (larvicidal, ovicidal and egg-parasitising capacity) and under naturally infested field conditions with selected strains. Repeated field trials were conducted with talc-based preparations of fungal strains at 10 kg ha^?1, which were applied mixed in farm yard manure (FYM) at 1.5 t ha^?1. Results (in vitro) showed that all tested isolates were capable to parasitise eggs, inhibit egg hatching and cause juvenile mortality of M. incognita at various levels. Based on the performance under in vitro studies, eight isolates (NDPL-01, ANDPL-02, SHGPL-03, HYBPL-04, AHDPL-05, PTNPL-06, SNGPL-07 and VNSPL-08) were re-tested to confirm the results. HYBDPL-04 was found causing highest mortality (80%), inhibition of egg hatching (90%) as well as parasitisation of M. incognita eggs (75%). Under field trials also, the best protection of root-knot disease of tomato (Lycopersicon esculentum L.), in terms of reduction of galls (61%) and reproductive factor (P_f/P_i (RF) = 0.2) was achieved through application of HYBDPL-04 + FYM compared to control and other tested isolates. It also enhanced marketable yield of tomato up to 43%. It is concluded that the HYBDPL-04 strain of P. lilacinum is highly effective for management of root-knot disease of tomato under naturally infested field conditions. It is the isolate which produced the maximum number of metabolites which were extracted through high pressure liquid chromatography.