Accumulation of arsenic and its distribution in rice plant (Oryza sativa L.) in Gangetic West Bengal, India

The presence of arsenic in irrigation water and in paddy field soil were investigated to assess the accumulation of arsenic and its distribution in the various parts (root, straw, husk, and grain) of rice plant from an arsenic effected area of West Bengal. Results showed that the level of arsenic in irrigation water (0.05–0.70 mg l⁻¹) was much above the WHO recommended arsenic limit of 0.01 mg l⁻¹ for drinking water. The paddy soil gets contaminated from the irrigation water and thus enhancing the bioaccumulation of arsenic in rice plants. The total soil arsenic concentrations ranged from 1.34 to 14.09 mg kg⁻¹. Soil organic carbon showed positive correlation with arsenic accumulation in rice plant, while soil pH showed strong negative correlation. Higher accumulation of arsenic was noticed in the root (6.92 ± 0.241–28.63 ± 0.225 mg kg⁻¹) as compared to the straw (1.18 ± 0.002–2.13 ± 0.009 mg kg⁻¹), husk (0.40 ± 0.004–1.05 ± 0.006 mg kg⁻¹), and grain (0.16 ± 0.001–0.58 ± 0.003 mg kg⁻¹) parts of the rice plant. However, the accumulation of arsenic in the rice grain of all the studied samples was found to be between 0.16 ± 0.001 and 0.58 ± 0.003 mg kg⁻¹ dry weights of arsenic, which did not exceed the permissible limit in rice (1.0 mg kg⁻¹ according to WHO recommendation). Two rice plant varieties, one high yielding (Red Minikit) and another local (Megi) had been chosen for the study of arsenic translocation. Higher translocation of arsenic was seen in the high yielding variety (0.194–0.393) compared to that by the local rice variety (0.099–0.161). An appreciable high efficiency in translocation of arsenic from shoot to grain (0.099–0.393) was observed in both the rice varieties compared to the translocation from root to shoot (0.040–0.108).     

Induction of fertilizable eggs by conspecific vitellogenin implantation in captive female walking catfish,Clarias batrachus (Linn.)

The synthesis of vitellogenin (Vg) is induced by conspecific Vg (Vg1 and Vg2) and estradiol‐17β (E₂) as demonstrated by the pattern of ³H‐serine incorporation in the liver and plasma proteins. The incorporation studies indicated that the label was first incorporated into the liver after which it appeared in the blood in both E₂‐ and Vg‐treated male catfish. Since Vg was capable of inducing its own synthesis, experiments were conducted in females during preparatory–prespawning period (March–May) to make them gravid by implanting Vg pellets. Two implantations of 4 mg Vg1 pellets into female catfish with an interval of 15 days, followed by laboratory maintenance for 45 days of initial implantation showed a significant increment in ovarian weight with concomitant formation of yolky oocytes through synthesis and incorporation of Vg, whereas Vg2 implantation was not effective in this regard. Histological observation of yolky oocytes in Vg1‐treated group showed the peripheral migration of germinal vesicle (eccentric germinal vesicle), which indicates the onset of maturation. On 45th day, third implantation with 2 mg Vg pellets was performed and after 15 days, fish were hormonally induced with a single injection of hCG (2,000 IU/kg fish). Six groups were considered such as initial control, BSA‐implanted control, Vg1‐implanted, Vg2‐implanted, catfish collected from the field on the last day of the experiment and catfish collected during spawning period in this experiment with 3–7 fish in each group. Each of the experimental fish was sexually mature and the body weight was between 100 and 125 g. The percentage of ovulation and fertilization in the eggs of Vg1‐implanted group was 91% and 78%, respectively, which was almost similar to that of gravid female catfish collected during breeding period (July). The breeding performance in BSA‐ and Vg2‐treated females was very poor. The fertilized eggs were hatched in the laboratory conditions. Thus, in the female catfish, Vg1 not only induces vitellogenesis but also makes the oocytes viable for fertilization.     

New slow-releasing molybdenum fertilizer

This paper describes a new water-insoluble molybdenum compound that has been developed as a slow-release fertilizer. The compound is an inorganic polymer formed by inclusion of molybdenum within a long-chain polyphosphate structure. It was designed by a process of "reverse engineering" of the molecule. Synthesis involved reaction of phosphoric acid with magnesium oxide, molybdenum trioxide, and sodium carbonate at 275 degrees C. Kinetics of reaction revealed complex multistage processes. X-ray diffraction patterns showed a crystalline nature with short-range as well as long-range ordering. The magnesium sodium polymolybdophosphate had ideal slow-release characteristics; it had low water solubility and high citrate solubility and was powdery, free flowing, and nonhygroscopic. Field testing showed an 80% increase in yield of green gram at a low dose of 0.04 kg/ha Mo. Nodulation increased by over 161%, and N content of gram increased by 20%. The slow-release fertilizer would provide an effective, low-cost, and environmentaly friendly alternative to Mo fertilization.     

Disposition kinetics,cytotoxicity and residues of fenvalerate in tissues following oral administration to goats

Disposition kinetics in goats of fenvalerate [(RS)-α-cyano-3-phenoxybenzyl (RS)-2-(4-chlorophenyl)-3-methylbutyrate] were studied after oral administration at 5 mg kg^?1. The insecticide persisted in blood for up to 48 h. The V_d(area), t_1/2(β), and t_1/2(Ka), of fenvalerate were 12.14 (±0.39) litre kg^?1, 12.25 (±0.25) h and 0.63 (±0.11)h, while the AUC and Cl_B values were respectively 7.35 (±0.39) μg h ml^?1 and 0.68 (±0.04) litre kg^?1 h^?1. The residues in tissues reached a peak four days after insecticide administration and then started to decline. Maximum residue was found in the adrenal gland, followed by liver, kidney and intestine. Both GOT and GPT activities in kidney tissue, but only GPT activities in liver tissue had decreased significantly 4, 8 and 22 days post-administration. The fenvalerate did not produce any significant effects on serum acetylcholinesterase, cholesterol or protein levels in goats. Histopathological examination showed fatty changes in the periphery of lobule, congestion in sinusoid, haemolysis in central vein, necrosis and periportal fibrosis around the central vein of liver, and necrosis in kidney of fenvalerate-treated goats.     

Transformation of Brassica oleracea var. capitata with bacterial betA gene enhances tolerance to salt stress

The bacterial betA gene for biosynthesis of glycinebetaine was transferred to cabbage (Brassica oleracea var. capitata) cultivar ‘Golden Acre’ through Agrobacterium-mediated transformation of hypocotyl explants. Transgenic status was established through Southern hybridization and mRNA expression in the shoots. The transformants exhibited higher tolerance to NaCl stress compared to untransformed parent plants. In physiological assessment of salinity tolerance, transgenics showed better growth response and greater stability in maintaining plant water relations at increasing levels of salinity. These results demonstrate that engineering glycinebetaine biosynthetic pathway into cabbage can lead to enhanced salt tolerance.     

Staling of Bread as Affected by Waxy Wheat Flour Blends

Crumb softness and improved shelf life of bread is often achieved by incorporating expensive shortenings in the formulation. We hypothesized that similar results could be achieved by blending bread wheat flour with waxy (low amylose) durum wheat flour. White pan bread was baked from 10, 20, and 30% waxy durum wheat flour composites and evaluated for loaf volume and crumb firmness over a period of 0, 3, and 5 days. The loaf volumes were not affected by the waxy flour blends. However, as staling progressed over 3–5 days, significant firming of crumb was observed in the control sample compared with loaves containing waxy flour. The firmness was inversely proportional to the level of waxy flour used in the blend. A 20% waxy wheat flour blend was optimal in retarding staling while producing bread quality comparable with the control. It was further established that bread made with 20% waxy flour gave lower firmness values after 5 days of storage in comparison to bread made with 3% shortening. These results suggest that 20% waxy wheat flour could substitute for use of shortening to achieve desirable crumb softness and to retard staling upon storage.     

Photodegradation of fenarimol

The photodegradation of aqueous alcoholic solutions of fenarimol at λ ≥ 250 nm has been examined. UV irradiation of an aqueous methanolic solution for 24 h yielded two photoproducts, identified as 2,4′‐dichlorobenzil and p‐chlorobenzoic acid, while irradiation of a solution in aqueous isopropanol yielded p‐chlorobenzoic acid and two additional products identified as 2,4′‐dichlorobenzophenone and o‐chlorobenzoic acid. A mechanism for the formation of the photoproducts is suggested. © 2000 Society of Chemical Industry