Allelopathic activity of root exudates from Leonurus sibiricus L. (Raktodrone)

Root exudates (RE) of Leonurus sibiricus L. show the stimulatory effect of a bioassay on rice, wheat and mustard. Root exudate shows concentration-dependent activity. A stock solution (one seedling in 200 mL of 0.1% Knop's solution for 4 days) is denoted as (1). A 10-fold higher concentration (10) was made by using a rotary vacuum evaporator; for example, 100 mL stock solution was reduced to 10 mL. For bioassay, (25), (50), (75) and (100)-fold concentrations have been used. The stimulatory effect increases with concentration (peak at 10), decreases thereafter, and at (50) (75) and (100), the effect is inhibitory (almost 100% at 75 and 100). Paper chromatography and staining suggest the presence of phenolics including caffeic acid in RE. Caffeic acid also shows the same concentration-dependent activity on rice seeds. An ether extract of acid hydrolyzed leaves shows a number of phenolics on thin layer chromatography. Among these phenolics, three are common with RE. One highly fluorescent band occurs in a much larger amount (both RE and acid hydrolyzed leaf extract), and coincides with standard caffeic acid. On ultraviolet spectrometer analysis after elution, the putative caffeic acid compound shows two characteristic peaks similar to that of caffeic acid at 277 and 231 nm, respectively. Gas liquid chromatography retention time of both standard caffeic acid and the fluorescent spot is the same.     

Differential expression of inducible nitric oxide synthase and cytokine mRNA in chicken lines divergent for cutaneous hypersensitivity response

Phytohemagglutinin (PHA)-induced delayed-type hypersensitivity is an immunocompetent trait considered an indicator of cell-mediated immune or T-cell responses. Divergent selection was performed to generate high and low lines for response to PHA-P. Extreme-responder birds of the F2 generation in each line were used to study possible differences in macrophage activity and the associated functional genes. To evaluate macrophage activity, nitric oxide (NO) was estimated both systemically in serum and in in vitro monocyte culture. Semi-quantitative RT-PCR was used to detect the differential mRNA expression patterns of iNOS and MIP-1beta in monocyte culture, whereas T(H)1 cytokines (IL-2 and IFN-gamma) were studied in peripheral blood mononuclear cells (PBMC) at different time intervals after lipopolysaccharide (LPS) induction. The high line showed strong systemic, as well as in vitro NO production, compared to the low line, upon stimulation with NDV and LPS, similar to early and high iNOS mRNA expression. Following the pattern of iNOS gene expression, an early strong expression of cytokines with powerful iNOS-inducing action, such as IFN-gamma and the chemokine MIP-1beta, was observed in the high line. In contrast, for response to PHA-P, low expression of IL-2 was observed in the high compared to the low line. In conclusion, the study revealed that divergent selection for response to PHA-P resulted in a divergent effect on T(H)1 cell activity, resulting in altered macrophage function in chickens. Selection, based on response to PHA-P, could lead to more resistant birds or birds with an enhanced immune response.     

Identifying critical parameters in the dynamics and control of microparasite infection using a stochastic epidemiological model

A stochastic epidemic model is presented to study infection transmission dynamics, and hence epidemic severity and disease incidence, in a closed population. The aim was to understand the relative importance of various parameters that influence the dynamics of potential epidemics, particularly when the genetic mechanisms of resistance or tolerance to infection are considered. Simulations explored the effect of varying the transmission coefficient, latent period, recovery period, mortality rate, and the period of loss of immunity on overall epidemic outcomes. The critical parameters influencing the transmission of infection, and hence disease incidence, were the transmission coefficient, the latent period, and the recovery period; the period of loss of immunity had only trivial effects. Ideally, control strategies should decrease the transmission coefficient and/or increase the latent period and/or decrease the recovery period. By equating measured traits with disease transmission parameters, the model described in this paper can be used to identify which disease resistance genes or QTL will be truly effective in helping to develop disease-resistant livestock that suffer fewer epidemics and side-effects of infection. In particular, emphases should be placed on finding genes that decrease the transmission of infection, increase the latent period, or decrease the recovery period.     

Variations in the Length of the Y Chromosome and the Seminal Attributes of Karan Fries Bulls

Fresh semen and blood samples from 20 Karan Fries bulls (4–6 years of age), maintained at the Artificial Breeding Complex of the National Dairy Research Institute, Karnal, were collected for one year. All the bulls had 60 chromosomes, comprising 58 acrocentric autosomes and 2 sex chromosomes, with X as the larger and Y as the smaller submetacentric. The mean lengths of Y_p and Y_q; the total length of the Y chromosome and the length ratio were 1.10±0.01 m, 1.83±0.02 m, 2.92±0.02 m and 62.46%±0.18%, respectively. Analysis of the length measurements of the the Y chromosomes in Karan Fries bulls showed that all the measurements, viz., the short arm of the Y chromosome, the long arm of the Y chromosome, the total length of the Y chromosome and the variation in length of Y chromosome, varied significantly among bulls. All the seminal parameters, the volume of semen, mass activity, initial motility, concentration, live sperm count and the total abnormal sperm count, were significantly affected by bulls, whereas season had a significant effect on all the seminal parameters except the total abnormal sperm count. No significant relationship between the ratio of the long arm to the total length of the Y chromosome and seminal attributes was observed.     

Assessment of the dynamics of microparasite infections in genetically homogeneous and heterogeneous populations using a stochastic epidemic model

The aim of this paper was to explore the effect of genetic heterogeneity in host resistance to infection on the population-level risks and outcomes of epidemics. This was done using a stochastic epidemiological model in which the model parameters were assumed to be genetically controlled traits of the host. A finite locus model was explored, with a gene controlling the transmission coefficient (i.e., host susceptibility to infection) and a gene controlling the recovery period. Both genes were simulated to have 2 alleles with underlying additive or dominance inheritance and an independent assortment of alleles. The model was parameterized for a viral pig disease (transmissible gastroenteritis), and complete homogeneous mixing among genotypes was assumed. Mean population genotype dramatically affected epidemic outcomes, and subtle effects of heterogeneity on epidemic properties were also observed. Genetic variation in the transmission coefficient led to probabilities of epidemics occurring that were slightly greater than expected, but genetic variation in the recovery rate had no such effect. Epidemics were generally less severe in genetically heterogeneous populations than expected from the constituent subpopulations. Furthermore, the genotype of the initial infected animal had a marked effect on epidemic probabilities, particularly when genetic variation was for recovery rate. The results of this model provide useful information to determine the optimum population structures and to exploit genetic variation in resistance to infection. Applications of the proposed model in genetically heterogeneous populations for identifying practical disease management strategies are also discussed.     

Comparative analysis of genome of Edwardsiella tarda by BOX-PCR and PCR-ribotyping

The Genus Edwardsiella comprises of bacteria differing strongly in their biochemical characteristics, physiological features, natural habitat and pathogenic properties. The most common species of the genus is Edwardsiella tarda, recovered from a variety of environmental and animal sources. In this study 51 isolates including one reference strain obtained from freshwater culture systems were analyzed for their genomic diversity by BOX-PCR and PCR-ribotyping. By comparison of fingerprint of different isolates 27 and 32 genotypes were obtained by PCR-ribotyping and BOX-PCR respectively. Cluster analysis of genetic profile obtained by BOX-PCR and ribotyping clearly showed 9 and 8 clusters respectively. Some correlation between BOX-PCR and ribotyping was observed. Several clusters delineated on the basis of source of isolation in the dendrogram by BOX-PCR with 70% cut off value had corresponding clusters in the ribotyping with 50% cut off value. Some of the genotypes were found to be habitat specific. However, there was mixing and dispersal of most of the genotypes obtained from water, sediment and fish samples. Of both the techniques, BOX-PCR was found to be more discriminating than ribotyping.     

Effect of substituting live feed with formulated feed on the reproductive performance and fry survival of Siamese fighting fish, Betta splendens (Regan, 1910)

This study aimed to elucidate the effect of partial or complete replacement of live feed (LF) (Tubifex) with formulated feed (FF) on the reproductive performance of Betta splendens. Three hundred B. splendens fry (average weight 0.19 ± 0.01 g) were equally distributed into five different groups, each with three replicates. They were fed for 105 days with following different diets: control (C)—100% LF; T1—75% LF, 25% FF; T2—50% LF, 50% FF; T3—25% LF, 75% FF, and T4—100% FF. Results showed that the average number of hatched larvae (654 ± 101) and fry survival after 2 weeks of rearing (428 ± 70), after completion of three spawning, were recorded highest in the control group, which was, however, not significantly different from the T1, T2, and T3 groups. At the end of the feeding trial, the highest hatching percentage (90.3%) was registered in the T2 group, which was not significantly different from the control and T1 groups. The T2 group also recorded highest fry survival (65.54%) after completion of three spawning, which was not significantly (P < 0.05) different from the T1 and T3 groups. Control diet contained higher saturated fatty acid (63.23%) than formulated diet (29.80%). In the whole-body tissue, highest level of EPA (0.42%) and DHA (3.13%) were found in the T4 group followed by T3 group. The DHA/EPA ration was recorded highest in the T2 group (10.96%), which did not differ significantly from the T1 and T3 groups. Significant positive correlation was observed between saturated fatty acid levels in fish whole-body tissue and number of hatched larvae (Y = 30.81 × −825.3, R ² = 0.968) and fry survival after 2 weeks of rearing (Y = 21.38 × −580.9, R ² = 0.967). Considering all these factors, it can be concluded that the live feed Tubifex can be replaced up to 50% without any adverse effect on the reproductive performance and fry survival of B. splendens.     

Small-scale agroforestry for upland community development: a case study from Chittagong Hill Tracts, Bangladesh

The potentialities of agroforestry are generally investigated through their biophysiological phenomena, cost–benefit analysis, and possible impact upon poverty reduction. There have been inadequate studies on the actual impacts of agroforestry intervention on small landholders and of farmers' attitudes toward these agroforestry programs. Drawing upon the findings of an empirical study, this article explores the effects of small-scale agroforestry on upland community development in the Chittagong Hill Tracts, Bangladesh. More specifically, the study clarifies the merits and demerits of different agroforestry systems as perceived by farmers, their impacts on the rural economy and the environment, farmers' attitudes toward the adoption of agroforestry, and impacts of various government policies. Field data were collected by administering questions to 90 randomly selected smallholders of the Upland Settlement Project (USP), as well as from project staff. The research tools employed were semistructured interviews, group discussions, and uncontrolled observations. The results indicated that the agroforestry interventions have in fact increased farmers' income through employment and the selling of farm products, as well as by improving the ecological conditions of these areas through reduction of soil erosion, increasing tree coverage, and maintaining soil fertility. The adoption of different agroforestry systems was governed mainly by the farmers' interests in following these techniques, their ability to cultivate the land in the prescribed manner, and the market demand for their products. The major obstacles that prevented increased agroforestry improvements included lack of confidence in new land-use systems, inappropriate project design (e.g., top-down innovation approach), and policy issues regarding land tenure. Recommendations are proposed to strengthen social capital in local organizations to enhance the livelihoods of the upland communities.