(R1493) Discussion on Stability and Hopf-bifurcation of an Infected Prey under Refuge and Predator

The paper deals with the case of non-selective predation in a partially infected prey-predator system, where both the susceptible prey and predator follow the law of logistic growth and some preys avoid predation by hiding. The disease-free preys get infected in due course of time by a certain rate. However, the carrying capacity of the predator population is considered proportional to the sum-total of the susceptible and infected prey. The positivity and boundedness of the solutions of the system are studied and the existence of the equilibrium points and stability of the system are analyzed at these points. The effect of the infected prey-refuge on each population density is also discussed. It is observed that a Hopf-bifurcation may occur about the interior equilibrium, where the refuge parameter is considered as the bifurcation parameter. The analytical findings are illustrated through computer simulation using MAPLE that show the reliability of the model from the ecological point of view

Bifurcation and Stability of Prey-Predator Model with Beddington-DeAngelis Functional Response

In this paper we discuss the harvesting of the prey species making a fraction of them to be accessed by the predator while both the prey and predator are being subjected to Beddington-DeAngelis functional response. It is observed that a Hopf-bifurcation may occur around the interior equilibrium taking the environmental carrying capacity of the prey species as the parameter. Some numerical examples and the corresponding curves are studied using Maple to explain the results of the proposed model

18β-glycyrrhetinic acid triggers curative Th1 response and nitric oxide up-regulation in experimental visceral leishmaniasis associated with the activation of NF-κB

The efficacy of 18β-glycyrrhetinic acid (GRA), a pentacyclic triterpene belonging to the β-amyrin series of plant origin, was evaluated in experimental visceral leishmaniasis. GRA is reported to have antitumor and immunoregulatory activities, which may be attributable in part to the induction of NO. Indeed, an 11-fold increase in NO production was observed with 20 µM GRA in mouse peritoneal macrophages infected with Leishmania donovani promastigotes. In addition to having appreciable inhibitory effects on amastigote multiplication within macrophages (IC50, 4.6 µg/ml), complete elimination of liver and spleen parasite burden was achieved by GRA at a dose of 50 mg/kg/day, given three times, 5 days apart, in a 45-day mouse model of visceral leishmaniasis. GRA treatment resulted in reduced levels of IL-10 and IL-4, but increased levels of IL-12, IFN-γ, TNF-α, and inducible NO synthase, reflecting a switch of CD4+ differentiation from Th2 to Th1. This treatment is likely to activate immunity, thereby imparting resistance to reinfection. GRA induced NF-κB migration into the nucleus of parasite-infected cells and caused a diminishing presence of IκB in the cytoplasm. The lower level of cytoplasmic IκBα in GRA-treated cells resulted from increased phosphorylation of IκBα and higher activity of IκB kinase (IKK). Additional experiments demonstrated that GRA does not directly affect IKK activity. These results suggest that GRA exerts its effects at some level upstream of IKK in the signaling pathway and induces the production of proinflammatory mediators through a mechanism that, at least in part, involves induction of NF-κB activation

Inventory of the traditional rice varieties in farming system of southern Assam: A case study

157-163Farmers in the rural parts of the North eastern region are still known to retain traditional rice varieties in their farming systems. In the present study, an attempt was made to inventorise the traditional rice varieties cultivated in<span style="mso-bidi-font-weight:bold; mso-bidi-font-style:italic"> a village in Barak Valley, North east India. A total of 18 rice landraces were collected from the study site retained by the farmers because of their dietary, cultural and social value. The traditional rice varieties possess several stress tolerant properties. Such properties act as positive factors in the retention of the rice landraces in the face of the increasing propaganda for cultivation of high yielding rice varieties. Traditional rice varieties represent important genetic reservoirs with valuable traits and there is an urgent need to provide proper incentives and encourage the farmers to cultivate rice landraces to help in the in situ conservation of this important gene pool. </span

Local soil knowledge of smallholder rice farmers: A case study in Barak Valley, Assam

94-99 Smallholder farmers in traditional farming systems are an untapped source of traditional knowledge. They are the managers of well-preserved local soil knowledge and folk soil taxonomy. In the present study rice farmers in Barak Valley, South Assam, were inventorised for local soil knowledge in relation to rice farming systems. The rice farmers were interviewed for the prevalence of folk soil taxonomy and a total of five major soil types were recorded. Since smallholder farmers practice their farming systems under various environmental factors, they on the basis of their local knowledge of soil, etc. shape the crop diversity. The study revealed that the farmers are faced with heterogeneous soil types and hence they maintain systematic classification criteria for the nomenclature of different soils, which was found to be positively correlated to scientific analysis of the soils. </smarttagtype

Deglycosylation Effect of the Mammalian Sperm Maturation Antigen (SMA2) on Serological Reaction and Acrosome Reaction

Spermatozoal membrane proteins are considered to possess several immunological unique characteristics as the cell is formed behind the blood-testes barriers. Major goat sperm maturation antigen (SMA2) contains one hexosamine along with mannose, galactose and glucose. In the present study, effects of deglycosylation of SMA2 antigen on immunoreactivity and the serological activity was investigated. SMA2 glycoantigen showed positive immunoreactivity after treatment with sodium borohydride (NaBH4) and moreover this generated a 44 kDa protein band which was negative for periodic acid Schiff reagent. Trifluoromethanesulfonic acid (TFMS) caused aggregation and restricted the free mobility of the treated antigen on SDS-PAGE and the protein band generated by TFMS treatment also showed positive immuno-reactivity. The results supported the views that the protein portion retains its immuno-reactivity even after oxidation of the vicinal hydroxyl group of saccharide component of SMA2 antigen. These data suggest that immunodominent epitopes exist on the core protein by which the SMA2 antigen retains its immuno-reactivity even after disruption of the saccharide portion. Additional experiments demonstrate that protein epitopes have a role in capacitation and the acrosome reaction (AR) in presence of antibody which is raised against this protein part of SMA2 using the negative staining of FITC-PSA (fluorescein isothiocyanate-labeled Pisum sativum agglutinin) probe. Altogether these findings indicate that the protein portion of SMA2 might fulfill the serological activity of the antigen as well as the protein epitope affects the acrosome reaction. In view of this property, we propose that the protein portion of SMA2 antigen might be considered as a potential antigenic target for an immune response

A method to obtain static potentials for electron-molecule scattering

We present a method for calculating the static potential of an arbitrary molecule which is represented by the well-known Gaussian wavefunctions. This potential is given in analytic form which, in additions to elementary functions, contains the error function for which simple and accurate methods for its evaluation exist. As an example we have used this potential, along with polarization-correlation and exchange potentials, to calculate the differential cross sections for the scattering of electrons from the water molecule in the energy range 30–100 eV. Comparison with previous calculations and experimental measurements show that this method produces accurate results for the differential scattering cross sections

18�-Glycyrrhetinic Acid Triggers Curative Th1 Response and Nitric Oxide Up-Regulation in Experimental Visceral Leishmaniasis Associated with the Activation of NF-�B1

The efficacy of 18�-glycyrrhetinic acid (GRA), a pentacyclic triterpene belonging to the �-amyrin series of plant origin, was evaluated in experimental visceral leishmaniasis. GRA is reported to have antitumor and immunoregulatory activities, which may be attributable in part to the induction of NO. Indeed, an 11-fold increase in NO production was observed with 20 �M GRA in mouse peritoneal macrophages infected with Leishmania donovani promastigotes. In addition to having appreciable inhibitory effects on amastigote multiplication within macrophages (IC50, 4.6 �g/ml), complete elimination of liver and spleen parasite burden was achieved by GRA at a dose of 50 mg/kg/day, given three times, 5 days apart, in a 45-day mouse model of visceral leishmaniasis. GRA treatment resulted in reduced levels of IL-10 and IL-4, but increased levels of IL-12, IFN-�, TNF-�, and inducible NO synthase, reflecting a switch of CD4� differentiation from Th2 to Th1. This treatment is likely to activate immunity, thereby imparting resistance to reinfection. GRA induced NF-�B migration into the nucleus of parasite-infected cells and caused a diminishing presence of I�B in the cytoplasm. The lower level of cytoplasmic I�B� in GRA-treated cells resulted from increased phosphorylation of I�B� and higher activity of I�B kinase (IKK). Additional experiments demonstrated that GRA does not directly affect IKK activity. These results suggest that GRA exerts its effects at some level upstream of IKK in the signaling pathway and induces the production of proinflammatory mediators through a mechanism that, at least in part, involves induction of NF-�B activation