Coumarin constituents of Selinum tenuifolium

Three furocoumarins, bergapten, heraclenin and heraclenol have been isolated from the roots of Selinum tenuifolium (Umbelliferae). Another coumarin, m.p. 85–86°, isolated from the same source and provisionally designated as ST-1, has been proved to be mixture of imperatorin, and 8-geranyloxypsolaren by analyses of various reaction products and separation by preparative TLC on silica gel G impregnated with silver nitrate.     

A comparison of some chemical tests for available soil nitrogen

Summary The total nitrogen uptake of wheat in a pot experiment was found to be linearly related to the amounts of applied nitrogen in the range of 0 to 120 pounds N per acre. The N-value of the soil used in the pot experiment was estimated by extrapolation of the regression line of total nitrogen uptakevs rates of added nitrogen. The N-value was compared with the values of available soil nitrogen as estimated by three chemical methods, two of which used alkaline KMnO₄ and the third, dilute H₂SO₄ as hydrolysing agents of soil organic nitrogen. Results obtained by none of these methods agreed closely with the N-value. The amounts of nitrogen estimated by Shihata's method and Purvis and Leo's method were practically same and were appreciably lower than N-value whereas the value obtained by Subbiah and Asija's method was much higher than the N-value. However, Purvis and Leo's method deserves further study as it is well suited for mass-scale analysis.     

Propagation of an Aβ Dodecamer Strain Involves a Three-Step Mechanism and a Key Intermediate

Proteinaceous deposits composed of fibrillar amyloid-β (Aβ) are the primary neuropathological hallmarks in Alzheimer disease (AD) brains. The nucleation-dependent aggregation of Aβ is a stochastic process with frequently observed heterogeneity in aggregate size, structure, and conformation that manifests in fibril polymorphism. Emerging evidence indicates that polymorphic variations in Aβ fibrils contribute to phenotypic diversity and the rate of disease progression in AD. We recently demonstrated that a dodecamer strain derived from synthetic Aβ42 propagates to morphologically distinct fibrils and selectively induces cerebral amyloid angiopathy phenotype in transgenic mice. This report supports the growing contention that stable oligomer strains can influence phenotypic outcomes by faithful propagation of their structures. Although we determined the mechanism of dodecamer propagation on a mesoscopic scale, the molecular details of the microscopic reactions remained unknown. Here, we have dissected and evaluated individually the kinetics of macroscopic phases in aggregation to gain insight into the process of strain propagation. The bulk rates determined experimentally in each phase were used to build an ensemble kinetic simulation model, which confirmed our observation that dodecamer seeds initially grow by monomer addition toward the formation of a key intermediate. This is followed by conversion of the intermediate to fibrils by oligomer elongation and association mechanisms. Overall, this report reveals important insights into the molecular details of oligomer strain propagation involved in AD pathology.     

Abiotic elicitors mediated elicitation of innate immunity in tomato: an ex vivo comparison

Improvement of the host resistance by using hazard free chemical elicitors is emerging as an alternative approach in the field of plant disease management. In our present work, we have screened the efficacy and possible mechanism of abiogenic elicitors like Dipotassium hydrogen orthophosphate (K₂HPO₄), Oxalic acid (OA), Isonicotinic acid (INA), Salicylic acid (SA), Acetylsalicylate (AS), Arachidonic acid (AA) and Calcium chloride (CaCl₂) to stimulate innate immune responses in Lycopersicum esculentum Mill. Excised tomato leaves, treated with elicitors at three different concentrations, were found to stimulate defense and antioxidative enzymes, total phenol and flavonoid content after 24 h of incubation. CaCl₂ (0.5 %) followed by INA (2.5 mM) were found most effective in activation of all such defense molecules in tomato leaves. Furthermore, nitric oxide (NO), a key gaseous mediator in plant defense signaling, was also measured after subsequent elicitor application. Higher doses of elicitors showed an elevated level of reactive oxygen species (ROS) generation, enhanced lipid peroxidation rate and proline content, which indicates the extent of abiotic stress generation on the leaves. However, ROS production, lipid peroxidation rate and proline concentration remain significantly reduced as a result of CaCl₂ (0.5 %) and INA (2.5 mM) application. A sharp increase of total chlorophyll content was also recorded due to treatment of CaCl₂ (0.5 %). These results demonstrate the effects of different abiogenic elicitors to regulate the production of defense molecules. Results also suggest that among all such chemicals, CaCl₂ (0.5 %) and INA (2.5 mM) can be used as a potential elicitor in organic farming of tomato.     

Alterations in Digestive Enzymes of Three Freshwater Teleostean Fishes by Almix Herbicide: A Comparative Study

Three freshwater teleostean fishes viz., Anabas testudineus (Bloch), Heteropneustes fossilis (Bloch) and Oreochromis niloticus (Linnaeus) were exposed to almix (66.67 mg/l) herbicide for 30 days to investigate the activity of digestive enzymes (amylase, lipase and protease) in stomach, intestine and liver. Amylase activity showed significantly high (p < 0.05) in all the fishes compared to control value and highest activity was observed in liver of A. testudineus (721.99 %) and minimum in intestine of H. fossilis (195.37 %). Lipase activity was also significantly increased (p < 0.05) in all the tissues; but highest in intestine of O. niloticus (235.51 %) and minimum in intestine of A. testudineus (130.51 %). Protease activity also showed similar trends of enhancement; it was maximum in stomach of O. niloticus (362.69 %), whereas in liver of H. fossilis it was rather less (173.72 %). Increased activity of digestive enzymes resulting from tissue damage ultimately affected the fish health due to impairment of digestive physiology confirming the herbicidal contamination on fish species. The sensitivity to the almix herbicide was pronounced in the order of O. niloticus > A. testudineus > H. fossilis.