High regenerative nature ofMentha arvensis internodes

Media and incubation conditions have been defined for highly efficient regeneration of shoots from internode explants of slow and fast growing cultivars ofMentha arvensis. Internodal segments excised from thein vitro raised shoots were inoculated on the MS medium supplemented with combinations of 5 concentrations of l-napthalene acetic acid (NAA) and 3 concentrations of 6-benzyl amino purine (BAP). The media containing 2 μg ml⁻¹ NAA, 10 Μg ml⁻¹ BAP and 1 μg ml⁻¹ NAA, 5 μg ml⁻¹ BAP proved best for shoot regeneration and growth responses on cv Himalaya and cv Kalka explants, respectively. In 12 weeks time, on average one explant of cv Himalaya produced about 200 shoots and that of cv Kalka produced about 180 shoots. The Himalaya explants required higher concentrations of NAA and BAP for high efficiency proliferation as compared to the Kalka explants. The experiments demonstrated that internodal tissue inMentha arvensis can be induced to obtain direct shoot regenerants with high efficiency. The analysis of the RAPD profiles of 100 regenerated plantlets each of cv Himalaya and Kalka showed more than 99.9% homogeneity in bands with respect to the parents.     

Evaluation of mucoadhesive properties of chitosan microspheres prepared by different methods

The mucoadhesive properties of chitosan microspheres prepared by different method were evaluated by studying the interaction between mucin and microspheres in aqueous solution. The interaction was determined by the measurement of mucin adsorbed on the microspheres. A strong interaction between chitosan microspheres and mucin was detected. The intensity of the interaction was dependent upon the method of preparation of chitosan microspheres and the amount of mucin added. The extent of mucus adsorption was proportional to the absolute values of the positive zeta potential of chitosan microspheres. The zeta potential in turn was found to be dependent upon the method of preparation of microspheres. The adsorption of type III mucin (1% sialic acid content) was interpreted using Freundlich or Langmuir adsorption isotherms. The values ofr ² were greater for Langmuir isotherm as compared with Freundlich isotherm. The adsorption of a suspension of chitosan microspheres in the rat small intestine indicated that chitosan microspheres prepared by tripolyphosphate cross-linking and emulsification ionotropic gelation can be used as an excellent mucoadhesive delivery system. The microspheres prepared by glutaraldehyde and thermal cross-linking showed good stability in HC1 as compared with microspheres prepared by tripolyphosphate and emulsification ionotropic gelation.     

Role of zinc in mitigating the toxic effects of chlorpyrifos on hematological alterations and electron microscopic observations in rat blood

The present study determined the protective potential of zinc in attenuating the toxicity induced by chlorpyrifos in rat blood. Male Sparque Dawley (SD) rats received either oral chlorpyrifos (13.5 mg/kg body weight) treatment every alternate day, zinc alone (227 mg/l in drinking water) or combined chlorpyrifos plus zinc treatment for a total duration of 8 weeks. The effects of different treatments were studied on various parameters in rat blood including haemoglobin (Hb) levels, total leukocyte count (TLC), differential leukocyte count (DLC), zinc protoporphyrins (ZPP), serum trace elemental concentrations and Scanning Electron Microscopic (SEM) observation of the blood cells. Chlorpyrifos treatment to normal control animals resulted in a significant decrease in TLC and ZPP concentration after 4 and 8 weeks. Chlorpyrifos treated animals also showed significant neutrophilia and lymphopenia after 8 weeks of toxicity. In addition, a significant decrease in serum zinc and iron concentrations were observed following chlorpyrifos intoxication, however, these animals responded with increased serum copper levels following the toxic treatment with this organophosphate. SEM studies of the red blood cells from chlorpyrifos treated animals indicated marked alterations in the topographical morphology of the various cell types, with the prominent feature being common aniscocytosis of the erythrocytes. Oral zinc treatment to the chlorpyrifos treated animals significantly improved the total leukocyte, neutrophil and lymphocyte counts, as well as the otherwise reduced concentrations of ZPP and the levels of various serum trace elements. Protective effects of zinc were also evident in the electron microscopic observations where most blood cell types depicted reverted to a close to the normal appearance. Based upon these data, the present study is first of its kind and suggests that zinc treatment considerably attenuates chlorpyrifos induced toxicity induced in restoring the altered hematological indices and morphological changes.     

A protocol for in vitro mass propagation of asiatic hybrids of lily through liquid stationary culture

Summary A simple, rapid and cost-effective in vitro scheme has been proposed for mass propagating two cultivars of Asiatic lily hybrids. An average of seven bulblets was formed after 17 d when 1×1 cm² bulb scale segments (explants) were cultured on Murashige and Skoog (MS) medium with 3% sucrose and 0.5 μM α-naphthaleneacetic acid (NAA). On MS medium containing 0.5 μM NAA and 6 or 9% sucrose, depending on the cultivar, large numbers of bulblets of increased size (3.5–5.0 cm in circumference) were formed under a 16/8 h photoperiod. A continuous system of mass propagation of bulblets was achieved through in vitro scale formation (secondary explants) on MS medium supplemented with 23 μM kinetin and 0.5 μM NAA, as well as scale proliferation on MS basal liquid stationary medium. Upon transplantation all bulblets sprouted, of which 40% flowered in the first season. Under ideal conditions, ca. 9.68×10⁵ bulblets can be produced from a single scale segment in 1 yr by following the systematic propagation steps proposed here.     

Role of calcium channel in postvagal potentiation of contraction as evident from the effects of Mn2+, La3+, D-600, and deoxycholate on isolated guinea pig atria-vagus nerve preparation

The role of the calcium channel in the first large contraction (postvagal potentiation, PVP) of the atria at the end of the inhibitory phase of its response (IPR) to vagal stimulation has been investigated by studying the effects of agents acting on the calcium channel (e.g., Ca2+, Mn2+, La3+, and D-600) or sarcoplasmic reticulum (SR) (e.g., deoxycholate (DOC)). IPR was potentiated by high [Ca2+]o (3-16 mM) and also by the calcium channel blockers, Mn2+ (1 microM-0.5 mM), La3+ (0.1 microM-0.5 mM), D-600 (1.0-10 microM), and DOC (1 microM-0.5 mM). PVP was also potentiated by enhanced [Ca2+]o, but the PVP ratio, which employs a correction for the simultaneous changes in the force of spontaneous contraction was inhibited. This indicated greater potentiation of contractility during spontaneous activity by Ca2+ than during PVP. Mn2+, La3+, and D-600 and even DOC in the above concentrations inhibited PVP but increased the PVP ratio. High concentrations of DOC (greater than 1 mM), which disrupt SR, strongly inhibited PVP. It is concluded that the calcium channel plays a more prominent role in spontaneous contractions than in PVP in guinea pig atria. PVP is suggested to be generated by excessive triggered release of Ca2+ from SR leading to a marked increase in [Ca2+]i. The calcium channel and the calcium trapped in the glycocalyx also play significant roles in PVP.     

Role of zinc in regulating the levels of hepatic elements following nickel toxicity in rats

This study was designed to determine the protective effects of zinc on the hepatotoxicity induced by nickel in rats. Female Sprague-Dawley (SD) rats received either nickel sulfate alone in the dose of 800 mg/L nickel in drinking water, zinc sulfate alone in the dose of 227 mg/L zinc in drinking water, and nickel plus zinc or drinking water alone for a total duration of 8 wk. The effects of different treatments were studied on activities of rat liver marker enzymes like alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferases (AST) and on the status of essential elements in rat liver. The study revealed a significant increase in the activities of enzymes ALP and ALT in rats subjected to nickel treatment. Interestingly, zinc supplementation to rats treated with nickel brought back the raised activities of these enzymes to within normal limits. Further, the levels of elements in liver that include zinc, copper, selenium, and potassium were found to be significantly suppressed following nickel treatment, whereas the levels of iron and sulfur were elevated. However, zinc treatment alone did not cause any appreciable change in the concentration of these elements. To the contrary, when zinc was given to nickel-treated rats, the concentrations of zinc, copper, potassium, and phosphorus were not significantly different from that of normal controls, whereas the levels of iron, selenium, and sulfur were improved in comparison to nickel-treated rats but were not within the normal limits. The present study concludes that zinc has the ability to maintain the levels of hepatic elements and has bearing in regulating the liver functions by maintaining the activities of marker enzymes in conditions of nickel toxicity.     

Biokinetics of iodine-131 in rat thyroid following lead and lithium supplementation

The impact of lead as an environmental pollutant on the I-131 uptake and retention in rat thyroid was assayed alone and in combination with lithium treatment. Lead treatment significantly stimulated the 2- and 24-h uptake of I-131 in the thyroid, and the 24-h uptake showed the maximum stimulation after 3 mo of lead treatment. On the contrary, lithium supplementation reduced the uptake significantly and the maximum decrease was noticed after 2 mo of lithium administration. Further, simultaneous lead and lithium treatment resulted in more pronounced increase in the uptake of I-131 by the thyroid, which was maximum after 3 mo of combined treatment. The thyroidal biological half-life of I-131 (T _biol) was found to be increased significantly following lead and lithium treatments when given separately. Interestingly, combined lead and lithium treatment given up to 2 mo further prolonged theT _biol of I-131, thus reflecting its increased retention.     

Purification and characterization of trypsin inhibitor from seeds of faba bean (Vicia faba L.)

A trypsin inhibitor from seeds of faba bean (Vicia faba L.) was purified to near homogeneity as judged by native-PAGE with about 11 % recovery using ammonium sulphate fractionation, ion-exchange chromatography on DEAE-cellulose and gel filtration through Sephadex G-100. The inhibitor had a molecular weight of 18 kD as determined by SDS-PAGE and Sephadex G-100. The inhibitor inhibited trypsin and chymotrypsin to the extent of 48 and 12 %, respectively. The inhibtion was of non-competitive type with dissociation constant for the enzyme inhibitor complex in the region of 0.07 mg·ml⁻¹. The inhibtor was stable between pH 4 and 5. It completely lost its activity when heated at 125 °C for 1 h or at 100 °C for 2 h. The inhibitor also lost its activity on exposure to 2-mercaptoethanol. Based on these properties, it could be concluded that Vicia faba trypsin inhibitor belongs to Bowman-Birk type of inhibitors, as it has molecular weight lower than generally observed for Kunitz type inhibitors.     

Positive correlation between menthol content andin vitro menthol tolerance inMentha arvensis L. cultivars

Menthol is a highly valued monoterpene produced by Japanese mint (Mentha arvensis) as a natural product with wide applications in cosmetics, confectionery, flavours, beverages and therapeutics. Selection of high menthol yielding genotypes is therefore the ultimate objective of all genetic improvement programmes inMentha arvensis. A positive correlation was observed in the present study between menthol content in oils of evaluated genotypes and the level of tolerance to externally supplied menthol of explants of these genotypes in culture medium. The easy use of this relationship as a selectable biochemical marker opens the practical applicability of largescalein vitro screening of the germplasm, clones and breeders' material for selection of elite genotypes.