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

Nath M  Woolliams JA  Bishop SC 《Journal of animal science》2008,86(8):1747-1757

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.  相似文献   

Replication of swine and equine influenza viruses in canine kidney cells.     

D M Nath  H C Minocha 《American journal of veterinary research》1977,38(7):1059-1061

Both swine and equine influenza viruses were replicated in Madin-Darby canine kidney cells. Hemagglutinin and complement-fixing antigens were synthesized at 4 to 8 hours postinfection and reached maximal synthesis at 16 to 20 hours. Neuraminidase activity increased 9- to 11-fold; 50% of the total hemagglutinin antigen was made before the infective virus progeny was detected.  相似文献   

Effect of different levels of calcium in a mixed ration using wheat bhoosa as roughage on the digestion of various nutrients and balances of Ca. P and N and various blood constituents in Hariana calves     

U C Saxena  V Mahadeven  K Nath 《The Indian veterinary journal》1967,44(7):596-602

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'Spent aniseed' (Pimpenella anisum) as a cattle feed     

K Nath  O N Agarwala  V Mahadevan 《The Indian veterinary journal》1966,43(10):908-912

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Forest-based betel leaf and betel nut People in Bangladesh： approach Lawachara National Park （LNP） farming of the Khasia indigenous to biodiversity conservation in     

Md. Jahirul Islam  Tapan Kumar Nath 《林业研究》2014,25(2):419-427

An exploratory survey was conducted among the Khasia living in Lawachara National Parkt （LNP） to investigate their depend- ency on the protected area （PA） for livelihoods, betel leaf hill farming, traditional forest conservation and perceptions of the PA, Field data were collected by interviewing 48 household heads from two villages （punjis） located inside the LNP and visiting their farms.： The economy of the Khasia was forest-based. They were largely dependent on betel leaf hill farming in LNP and nearly 71% of their mean annual income was de- rived from this irrespective of farmer category. On average, about 14% of the incomes of the poorer farmers came from forest produce followed by 10% and 6% for medium and rich farmers respectively. Hills and forests were the foundations of their lives and livelihoods, and LNP was the life-blood of Khasia survival. As a sustainable production system, this farming practice plays a vital role in conserving biodiversity in LNP and might be replicated elsewhere.  相似文献   

Molecular characterization and xenogenic application of wharton’s jelly derived caprine mesenchymal stem cells     

M. D. Pratheesh  Nitin E. Gade  Pawan K. Dubey  Amar Nath  T. B. Sivanarayanan  D. N. Madhu  Bhaskar Sharma  Amarpal  G. Saikumar  G. Taru Sharma 《Veterinary research communications》2014,38(2):139-148

Aim of the present study was in vitro expansion and characterization of caprine wharton’s jelly derived mesenchymal stem cells (cWJ-MSCs) to investigate their tissue healing potential in xenogenic animal model. Plastic adherent fibroblastoid cell populations with distinctive homogeneous morphology were isolated from caprine wharton’s jelly explants. These wharton’s jelly derived cells were found positive for the surface markers CD-73, STRO-1 and CD-105, whereas they were negative for hematopoetic stem cell marker CD-34. In vitro cultured cWJ-MSCs also showed differentiation properties into osteogenic, adipogenic and chondrogenic lineages as demonstrated by von Kossa, Oil Red- O and Alcian blue staining respectively, which was further confirmed and quantified by flow cytometric analysis. Furthermore, these well characterized cWJ-MSCs were evaluated for the wound-healing potential in full-thickness skin wounds in rabbit model for 28 days. Caprine WJ- MSCs treated skin wounds showed significantly (P?<?0.05) higher percentage of wound contraction especially at the 21^st day post transplantation when compared to PBS treated control group animals. Further, we observed better healing potential of cWJ-MSCs in terms of histo-morphological evaluation, epithelialisation and collagenization with matured vascularization stage by day 28 as compared to control. In conclusion, cWJ- MSCs provide an alternative inexhaustible source of mesenchymal stem cells and also unravel new perspectives pertaining to the therapeutic use of these cells in different species.  相似文献   

Chemical signature of the superconducting phase in the nd-ce-cu-o system     

Nath A  Kopelev NS  Chechersky V  Peng JL  Greene RL  O BH  Larkin MI  Markert JT 《Science (New York, N.Y.)》1994,265(5168):73-74

The electron-doped material Nd2-xCexCuO(4) becomes superconducting with a Ce(4+) composition around 0.16, but only after removal of a minuscule amount of extraneous oxygen. This enigmatic behavior was addressed here. A small fraction of copper in the CuO(2) planes of Nd2-xCexCuO(4) was substituted by cobalt-57, which serves as a microprobe of the chemical environment. Deoxygenation brought about little change in the M?ssbauer spectra both above and below the optimal superconducting concentration; however, for x = 0.16 a change was observed. In the latter, a major fraction of the magnetically split, five-coordinate species showed itself as a paramagnetically relaxed doublet upon deoxygenation. The abundance of the paramagnetically relaxed species corresponds closely to the diamagnetic volume fraction and thus provides a microscopic signature of the superconducting phase.  相似文献   

Non-arrowing and broad-leaved mutants in Rhodes grass (Chloris gayana Kunth.)     

G. Krishna  G. Shivashankar  J. Nath 《Euphytica》1984,33(2):525-528

Summary Non-arrowing and broad-leaved mutants of Rhodes grass have been isolated following gamma irradiation. The green forage yield in non-arrowing and broad-leaved types were respectively 67 and 171 percent more than the control. Crude protein, nitrogen and calcium fractions nearly doubled in the non-arrowing type and remained approxymately the same in the broad-leaved type over controls.  相似文献   

Comparative potential of phenotypic,ISSR and SSR markers for characterization of sesame (<Emphasis Type="Italic">Sesamum indicum</Emphasis> L.) varieties from India     

Vinod Kumar  Satyendra Nath Sharma 《Journal of Crop Science and Biotechnology》2011,14(3):163-171

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Effect of Climatic Variation on Yield of Sesame (Sesamum indicum L.) at Different Dates of Sowing     

R. Nath  P. K. Chakraborty  & A. Chakraborty 《Journal of Agronomy and Crop Science》2001,186(2):97-102

Although experiments have previously been carried out to determine the optimum sowing time of sesame, very few attempts have been made to determine the effects of macro and micro climatic variation on yield. Thus a field experiment was conducted at the University Research Farm, Bidhan Chandra Krishi Viswavidyalaya, Kalyani, India on an Entisol (alluvial, sandy loam) in the summer seasons of 1996 and 1997 to assess the effects of macro and micro climatic variations on yield of sesame for various dates of sowing. The number of seeds per capsule of sesame was highest in the crop sown on 19 February, although up to the 18 April sowing there was no significant variation. There was no appreciable variation in thousand-seed weight with date of sowing. Crops sown on 19 February and 1 March produced statistically similar yields. The average reduction in yield of sesame was 78.5 and 213 %, respectively, for crops sown on 10 February and 28 April, compared with the crop sown on 19 February. The cultivar Rama produced higher yields than B-67 and Kanke-1. Ambient temperature above 30 °C up to 100 % flowering had a direct positive effect on sesame yield. Crop exposure to 60–70, 70–80 and  80 % relative humidity up to 100 % flowering had a direct negative effect. Temperature profile at 50 days after emergence (DAE), relative humidity at 60 DAE, and photosynthetically active radiation (PAR) at 30 and 40 DAE within the crop canopy had direct positive effects on yield. Regression models suggested that temperature profile and PAR within the crop canopy produced 72 and 35 % variation in yield, respectively.  相似文献