Genetic Analysis of Resistance to Xanthomonas campestris pv. oryzae (Ishiyama) Dye in a Rice Breeding Line ARC 10464

The genetics of resistance to three Indian pathotypes of Xanthomonas campestris pv. oryzae, namely, IX01, IX08 and IX09, was studied in a landrace of Indica rice ‘ARC 10464’. Resistance to each of the two pathotypes IX01 and IX09 was governed by two independently-inherited dominant genes while a single dominant gene was operative against patho-type 1X08. The joint segregation tests conducted on F₂ plant progenies (F₃ families) using pathotypes IX01, IX08 and IX09 suggested that the gene/(s) effective against each of the pathotypes are different.     

Genetic analysis of a CSR10 (indica) × Taraori Basmati F3 population segregating for salt tolerance using ISSR markers

Segregation for salinity tolerance and ISSR markers based molecular polymorphism were investigated in a F₃ plant population raised via single-seed descent method from a cross between salt-tolerant indica rice variety CSR10 and salt-susceptible premium traditional Basmati rice variety Taraori Basmati HBC19. A total of 130 F₃plants were evaluated individually for salinity tolerance on 1–9 scale on the basis of seedling growth parameters; the average score ranged between 1.7 to 8.3. Frequency distribution curve obtained using the salinity tolerance data of F₃ population and a chi-square analysis, showed a good fit to a normal distribution. Eleven plants each in the category of salt-tolerant and salt-susceptible were selected from the segregating F₃ population for ISSR marker analysis. A total of 149 bands (4–11 bands per primer) ranging from 200 to 3530 bp were scored for the two rice varieties and the selected CSR10 × HBC19 segregating F₃ plants using 26 ISSR primers. Of these, 89 were monomorphic and 60 were polymorphic. Of the 60 polymorphic bands,36 and 20 bands were specific to CSR10 andHBC19 respectively. The remaining four bands were amplified using UBC primers 810,848, 853 and 886 and present in only some of the CSR10 × HBC19 F₃ plants. Notably, ISSR primers with dinucleotide repeat motif and 5'-anchored end amplified more number of bands (7.0 bands/primer) compared to3'-anchored dinucleotide primers (5.4bands/primer), but 3'-anchored dinucleotide primers revealed higher level of polymorphism (2.6 polymorphic bands/primer) compared to 5'-anchoreddinucleotide primers (1.43 polymorphic bands/ primer). While distribution of majority of the polymorphic bands were more or less in the expected ratios in salt-tolerant and/or salt-sensitive F₃segregating plants, but some of the bands amplified using UBC ISSR primers 823, 825,826, 849, 853, 864, 866 and 884 showed highly skewed distribution. Such polymorphic bands stand greater chances of having a linkage with the genes/ QTLs for salinity tolerance and shall be the target for further studies. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genes Lr48 and Lr49 for hypersensitive adult plant leaf rust resistance in wheat (Triticum aestivum L.)

The genetic bases of leaf rust resistance in wheat (Triticum aestivum L.) line CSP44, selected from the Australian cultivar Condor, and Indian cultivar VL404, were studied. The reaction patterns of CSP44 and VL404 against Indian races 12, 77, 77-1, 77-2, 77-3, 77-4, 77-5 and 108 were different from reaction patterns shown by near-isogenic lines with known adult plant resistance (APR) genes, viz. Lr12, Lr13, Lr22b and Lr34. Although the reaction patterns of CSP44 and VL404 were similar to the near-isogenic line Tc+Lr22a, tests of allelism indicated absence of Lr22a in both CSP44 and VL404. On the basis of genetic studies, their resistances in field tests against race 77-5, the most virulent race from the Indian sub-continent, were each ascribed to two genes. One of the two genes in each wheat was identified to be the non-hypersensitive APR gene Lr34. The second APR genes in CSP44 and VL404 gave hypersensitive reaction types and were recessive and dominant, respectively. The gene in CSP44 was designated Lr48and the gene in VL404, Lr49. This revised version was published online in August 2006 with corrections to the Cover Date.     

Ringlike structure of the Deinococcus radiodurans genome: a key to radioresistance?

The bacterium Deinococcus radiodurans survives ionizing irradiation and other DNA-damaging assaults at doses that are lethal to all other organisms. How D. radiodurans accurately reconstructs its genome from hundreds of radiation-generated fragments in the absence of an intact template is unknown. Here we show that the D. radiodurans genome assumes an unusual toroidal morphology that may contribute to its radioresistance. We propose that, because of restricted diffusion within the tightly packed and laterally ordered DNA toroids, radiation-generated free DNA ends are held together, which may facilitate template-independent yet error-free joining of DNA breaks.     

Immune response of chicks to oral vaccination against Newcastle disease and fowl pox

The humoral immune response and immunity conferred in chicks were compared following separate and combined oral vaccination with F strain of Newcastle disease virus (NDV) and HP1 strain of fowl pox virus. The haemagglutination inhibition (HI) antibody titre against NDV and passive haemagglutination (PHA) antibody titre against fowl pox virus were comparable in two respective groups. The serum IgG concentration increased significantly after the second vaccination in all the groups. The NDV vaccine induced significantly higher IgG production as compared to fowl pox virus vaccine. There was no significant difference in serum IgG concentration produced by combined vaccine and separate F strain vaccine. The protection afforded by combined and separate vaccinations did not vary significantly against challenge with virulent strains of NDV and fowl pox virus at different stages.     

Production of Wild Buffalo (Bubalus arnee) Embryos by Interspecies Somatic Cell Nuclear Transfer Using Domestic Buffalo (Bubalus bubalis) Oocytes

The objective of this study was to explore the possibility of producing wild buffalo embryos by interspecies somatic cell nuclear transfer (iSCNT) through handmade cloning using wild buffalo somatic cells and domestic buffalo (Bubalus bubalis) oocytes. Somatic cells derived from the ear skin of wild buffalo were found to express vimentin but not keratin and cytokeratin‐18, indicating that they were of fibroblast origin. The population doubling time of skin fibroblasts from wild buffalo was significantly (p < 0.05) higher, and the cell proliferation rate was significantly (p < 0.05) lower compared with that of skin fibroblasts from domestic buffalo. Neither the cleavage (92.6 ± 2.0% vs 92.8 ± 2.0%) nor the blastocyst rate (42.4 ± 2.4% vs 38.7 ± 2.8%) was significantly different between the intraspecies cloned embryos produced using skin fibroblasts from domestic buffalo and interspecies cloned embryos produced using skin fibroblasts from wild buffalo. However, the total cell number (TCN) was significantly (p < 0.05) lower (192.0 ± 25.6 vs 345.7 ± 42.2), and the apoptotic index was significantly (p < 0.05) higher (15.1 ± 3.1 vs 8.0 ± 1.4) for interspecies than that for intraspecies cloned embryos. Following vitrification in open‐pulled straws (OPS) and warming, although the cryosurvival rate of both types of cloned embryos, as indicated by their re‐expansion rate, was not significantly different (34.8 ± 1.5% vs 47.8 ± 7.8), the apoptotic index was significantly (p < 0.05) higher for vitrified–warmed interspecies than that for corresponding intraspecies cloned embryos (48.9 ± 7.2 vs 23.9 ± 2.8). The global level of H3K18ac was significantly (p < 0.05) lower in interspecies cloned embryos than that in intraspecies cloned embryos. The expression level of HDAC1, DNMT3a and CASPASE3 was significantly (p < 0.05) higher, that of P53 was significantly (p < 0.05) lower in interspecies than in intraspecies embryos, whereas that of DNMT1 was similar between the two types of embryos. In conclusion, these results demonstrate that wild buffalo embryos can be produced by iSCNT.     

Comparison of three techniques for the diagnosis of urinary tract infections in dogs with urolithiasis

OBJECTIVES: To identify an appropriate sampling technique(s) to accurately detect the bacteria causing urinary tract infections in dogs with urolithiasis. METHODS: Twenty-one dogs with urolithiasis were included in the study. Three types of samples were taken from each dog. Urine was collected by cystocentesis, and a urinary bladder mucosal biopsy and urolith were retrieved during cystotomy. The samples were then cultured on blood agar and MacConkey's agar to identify the bacteria associated with urinary tract infections. RESULTS: Bacterial urinary tract infection was found in 16 cases (76.19 per cent). The most prevalent bacteria found to cause urinary tract infection were Escherichia coli (n=7), followed by coagulase-positive Staphylococcus species (n=4), Klebsiella pneumoniae (n=2), Pseudomonas aeruginosa (n=2) and Proteus mirabilis (n=1). In the case of a positive urine culture, the same bacteria were also cultured from the urinary bladder mucosal biopsy alone or from both the urinary bladder mucosal biopsy and urolith. However, in the case of a negative urine culture, bacteria were found to be present in the urinary bladder mucosal biopsy or urolith cultures in 23.81 per cent of dogs. The uroliths that gave positive culture results were either infection-induced uroliths composed of struvite and calcium carbonate phosphate, ammonium acid urate only or metabolic uroliths composed of calcium oxalate and calcium phosphate, or calcium phosphate only. All the uroliths that gave negative culture results were metabolic uroliths composed of calcium oxalate and/or calcium phosphate, and uric acid and calcium phosphate. CLINICAL SIGNIFICANCE: When the culture from the urine obtained by cystocentesis is negative, cultures of urinary bladder mucosal biopsy and urolith are recommended in dogs with urolithiasis in order to accurately assess the microbiological status of the urinary tract.     

Feed consumption, nutrient utilization and serum metabolite profile of captive blackbucks (Antelope cervicapra) fed diets varying in crude protein content

A feeding trial was conducted to determine the optimum level of crude protein (CP) in the diet of captive blackbuck (Antelope cervicapra) in which feed consumption and nutrient utilization are maximal. Fifteen blackbucks (BW 25-34 kg) were distributed into three groups of five each in an experiment of 75-days duration including a digestion trial of 5-day collection period. All the animals were offered 200 g of concentrates and fresh maize fodder ad libitum. The overall CP content of the three respective diets was 6.9%, 10.4% and 12.7%. Blood samples were collected on the last day of the experiment. Intake and digestibility of CP increased (p < 0.01) with the increased level of CP in the diet. Feed consumption and nutrient intake were not significantly different among the groups. However, digestibilities of most of the nutrients were higher in the 10.4% CP diet than in the 6.9% CP diet. The endogenous loss of nitrogen was similar among the groups. Based on the endogenous losses, minimum N requirement was calculated to be 776 mg/kg BW(0.75) /day, and to meet this requirement, diet must contain at least 8.27% CP. Serum urea nitrogen concentration increased (p < 0.01) with increased level of dietary CP. Serum level of glutamate oxaloacetate transaminase and glutamate pyruvate transaminase was higher (p < 0.05) in the group fed 6.9% CP diet. Animals in the group fed low protein diet also lost body mass during the experimental period. It was concluded that a diet containing 10.4% CP was optimum for maximizing nutrient utilization without any adverse effect on voluntary feed consumption and serum metabolite profile of blackbucks.     

Feed consumption,diet digestibility and mineral utilization in captive blackbuck (Antelope cervicapra) fed different levels of concentrates

A feeding trial was conducted to know the level of concentrates in the diet of Antelope cervicapra at which diet digestibility and mineral utilization were optimum. Fifteen blackbucks (25–33 kg BW) were distributed into three groups of five each. Fresh oat (Avena sativa) and berseem (Trifolium alexandrinum) fodders were offered ad libitum to all the animals. In addition, animals in groups II and III received concentrate mixture at the rate of 0.5 and 1% of BW, whereas animals in group I received no concentrates. As the level of concentrates increased, consumption of fodder decreased resulting in decreased consumption of neutral detergent fibre (NDFom), acid detergent fibre (ADFom), hemicellulose and cellulose. However, overall total dry matter (DM) and organic matter (OM) intake was not significantly different between the groups. Digestibility of DM, OM and gross energy (GE) increased while that of NDFom and ADFom decreased with increased level of concentrates in the diet. Intake of P, Zn, Cu and Mn increased with increased level of concentrate supplementation; however, consumption of Ca and Fe followed the reverse trend. Absorption of P and Zn increased with increased level of concentrate supplementation. Serum concentration of Zn increased when concentrate was supplemented at the rate of 0.5% BW beyond which there was no further improvement. Increasing the level of concentrates in the diet was resulted in increased serum glucose and cholesterol levels. Forage‐only diet was inadequate in supply of energy, P and zinc. Supplementation of concentrates at the rate of 0.5% BW was able to meet the requirement of these nutrients. Supplementation at the rate of 1% BW supplied energy and P in excess of requirement. It was concluded that the feeding of concentrates to the captive blackbuck fed forage‐based diets should be restricted to 0.5% of BW.