Comparative sensitivity of carp, Cyprinus carpio L. and rainbow trout, Salmo gairdneri Richardson, to Renibacterium salmoninarum

Abstract. The pathogenicity of Renibacterium salmoninarum to carp, Cyprinus carpio L., and rainbow trout, Salmo gairdneri Richardson, was investigated. All carp injected with 4·8 × 10⁸ cells/fish, or 4·8 × 10⁷ cells/fish survived for 38 days. R. salmoninarum was isolated from all moribund fish, but not from the kidney of surviving fish, although R. salmoninarum antigen was detected in several of these fish by the dot blot assay. On the other hand, mortality in rainbow trout was 95% in the fish injected with 4·8 × 10⁸ cells/fish, and 15% in those which received 4·8 × 10⁷ cells/fish. R. salmoninarum antigen was detected by the dot blot assay in all surviving rainbow trout. The number of R. salmoninarum cells was immediately decreased by carp or rainbow trout serum, and the serum bactericidal activity of carp was higher than that of rainbow trout. Carp blood leucocytes had higher phagocytic activity than those of rainbow trout.     

Validation and application of real-time polymerase chain reaction assays for representative rumen bacteria

Real‐time polymerase chain reaction (PCR) assays for 11 representative rumen bacterial species were validated. The sensitivity was tested by using the serially diluted target 16S rDNA from respective bacterial species. The recovery of the target DNA and the assay reproducibility were determined using DNA from rumen fluid spiked with different quantities of the target. Minimum detection levels for the target were 10–100 copies in pure culture. The recovery of the added target ranged from 82.4 to 116.6%. The intra‐ and inter‐assay variations of each assay were <9.4 and <12.6%, respectively. Therefore, the real‐time PCR assays evaluated in the present study are considered to be sufficiently reliable for monitoring all 11 bacterial species in the rumen. The assays were then applied to the monitoring of the bacterial species attached to ruminally incubated rice straw. Among the monitored fibrolytic species, Fibrobacter succinogenes was found to be the most dominant, accounting for 2.61% of total bacteria after 24 h incubation. Selenomonas ruminantium and Streptococcus bovis, non‐fibrolytics, were detected on the rice straw at 8.96% and 1.16% of total bacteria, respectively. Such high levels of non‐fibrolytics on the plant fiber suggest a synergistic relationship between fibrolytics and non‐fibrolytics.     

Detection of monoclonal integration of bovine leukemia virus proviral DNA as a malignant marker in two enzootic bovine leukosis cases with difficult clinical diagnosis

Monoclonal integration of bovine leukemia virus (BLV) proviral DNA into bovine genomes was detected in peripheral blood from two clinical cases of enzootic bovine leukosis (EBL) without enlargement of superficial lymph nodes. A BLV-specific probe hybridized with 1 to 3 EcoRI and HindIII fragments in these 2 atypical EBL cattle by Southern blotting and hybridization, as well as in 3 typical EBL cattle. The probe also hybridized to a large number of EcoRI and HindIII fragments in 5 cattle with persistent leukosis. These results suggest that the detection of monoclonal integration of BLV provirus into the host genome may serve as a marker of monoclonal proliferation and malignancy in difficult to diagnose EBL cattle.     

The profile of urinary lipid metabolites in healthy dogs

Polyunsaturated fatty acids, including arachidonic acid (AA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), are converted to hundreds of lipid mediators by cyclooxygenases (COX), lipoxygenases (LOX), and cytochrome P450 (CYP), or through non-enzymatic processes, and they reflect inflammatory states of the body. We comprehensively analyzed lipid metabolites in dog urine using a liquid chromatograph-mass spectrometry (LC-MS/MS) to describe their metabolic characteristics. We detected 31 AA-derived metabolites, four EPA-derived metabolites, and a DHA-derived metabolite in all urine samples. Among AA-derived metabolites, 15, 5, 3, and 8 were generated by COX, LOX, CYP, and non-enzymatic oxidation respectively. This study will be the first step to use profiles of urinary lipid metabolites for better understanding and diagnosis of canine diseases.     

Nod2 mutation in Crohn's disease potentiates NF-kappaB activity and IL-1beta processing

Variants of NOD2, an intracellular sensor of bacteria-derived muramyl dipeptide (MDP), increase susceptibility to Crohn's disease (CD). These variants are thought to be defective in activation of nuclear factor kappaB (NF-kappaB) and antibacterial defenses, but CD clinical specimens display elevated NF-kappaB activity. To illuminate the pathophysiological function of NOD2, we introduced such a variant to the mouse Nod2 locus. Mutant mice exhibited elevated NF-kappaB activation in response to MDP and more efficient processing and secretion of the cytokine interleukin-1beta (IL-1beta). These effects are linked to increased susceptibility to bacterial-induced intestinal inflammation and identify NOD2 as a positive regulator of NF-kappaB activation and IL-1beta secretion.     

Effects of food enriched with egg yolk hydrolysate (bone peptide) on bone metabolism in orchidectomized dogs

We examined the effects of chicken egg hydrolysate (also known as “bone peptide” or BP) on bone metabolism in 5- to 8-month-old orchidectomized dogs. The bone formation marker serum bone alkaline phosphatase (BAP) and the bone resorption marker urine deoxypyridinoline (DPD) were used as indicators to measure changes in bone metabolism. The following results were observed that Serum BAP was higher in dogs fed BP-enriched food throughout the clinical investigation. Serum BAP was statistically significantly higher in dogs fed BP-enriched food than in dogs fed non-BP-enriched food at 2 months after orchidectomy. This suggests that BP promoted bone formation immediately after orchidectomy.     

Hypoxia inducible factor 1α expression and effects of its inhibitors in canine lymphoma

Hypoxic conditions in various cancers are believed to relate with their malignancy, and hypoxia inducible factor-1α (HIF-1α) has been shown to be a major regulator of the response to low oxygen. In this study, we examined HIF-1α expression in canine lymphoma using cell lines and clinical samples and found that these cells expressed HIF-1α. Moreover, the HIF-1α inhibitors, echinomycin, YC-1 and 2-methoxyestradiol, suppressed the proliferation of canine lymphoma cell lines. In a xenograft model using NOD/scid mice, echinomycin treatment resulted in a dose-dependent regression of the tumor. Our results suggest that HIF-1α contributes to the proliferation and/or survival of canine lymphoma cells. Therefore, HIF-1α inhibitors may be potential agents to treat canine lymphoma.