Phagocytic activity of macrophages of rainbow trout against Vibrio anguillarum and the opsonising effect of antibody and complement

The phagocytosis of Vibrio anguillarum by peritoneal macrophages from normal rainbow trout was enhanced by antibody and complement. Treatment of either macrophages or the bacteria by antibody also enhanced opsonisation. Five weeks after immunisation with V anguillarum, the phagocytic activity of macrophages from rainbow trout was increased significantly compared with the activity of those from unvaccinated fish. Although agglutinin titres did not increase until three weeks after immunisation, seven out of 10 fish challenged one week after immunisation survived, indicating that immunised fish had developed resistance to vibrio infection before significant levels of antibody or phagocytic activity became detectable.     

Detection of fish antibody against protein antigen of Aeromonas salmonicida by enzyme-linked immunosorbent assay using biotin-avidin system

Antibody against Aeromonas salmonicida was detected in sera from immunised or experimentally infected rainbow trout by enzyme-linked immunosorbent assay (ELISA) using the biotin-avidin system. The ELISA titre correlated well with the agglutinin titres of the sera, but the ELISA was found to be more sensitive than the agglutination test. When the rainbow trout serum was separated by column chromatography, antibody activity (determined by ELISA and agglutination test) was detected in the IgM fractions. Minimum cross reaction was observed in the ELISA system between antigen prepared from A salmonicida and antibodies against Vibrio species and other species of Aeromonas. The specificity of the ELISA was also confirmed by inhibition test. Immunisation of rainbow trout with a virulent strain of A salmonicida provided good protection, though no correlation was observed between the protection and the ELISA titres of sera.     

Occurrence of blood disease of banana in Sumatra,Indonesia

Since 1991, the sudden death of cultivated banana plants has been widely observed in the southern region of Sumatra Island, Indonesia. Wilting from loss of petiole and midrib turgidity, yellowing, and necrosis of leaves was followed by death of the whole plant. Reddish brown bacterial ooze exuded from the cut surface of infected pseudostems and fruits. The colony appearance of the isolated bacterium was similar to that of Ralstonia solanacearum. The bacterium was pathogenic to banana plants but not to tomato. Its bacteriological properties agreed with those of blood disease bacterium (BDB) of banana described previously. The 16S rDNA sequence of strain Banana E had conserved bases characteristic of BDB. Based on these results, the causal agent was identified as BDB, which is a close relative of Ralstonia. The isolates have resistance against antibiotics, such as chloramphenicol and tetracycline.The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under the accession number AB095535     

Allele frequency distribution of the canine dopamine receptor D4 gene exon III and I in 23 breeds

Various canine breeds are remarkably different from each other not only in their sizes and shapes but also in behavioral traits, suggesting that some of them are under genetic control. Although dopaminergic neurotransmission system is considered to affect animal behavior, little is known about related genes in canine. Relations between specific alleles in polymorphic regions of the dopamine receptor D4 gene (DRD4) and personality or psychiatric disorders have been reported in humans, and we first found polymorphism in exon III region of the gene in 4 canine breeds. In this study we surveyed allele frequency distribution in 23 breeds including a total of 1,535 unrelated individuals. In exon III, 8 alleles including a novel allele were identified. A group of breeds in which the alleles 447b, 498 and 549 were frequent tended toward high scores in aggression-related behavioral traits than that with frequent alleles 435 and 447a. Moreover, a polymorphism based on 24 bp insertion/deletion was found in exon I region for the first time in dogs. This information may be of use for candidate gene studies of behavioral variation in dogs.     

An experimental study of apico-aortic valved conduit (AAVC) for surgical treatment of aortic stenosis in dogs

A new valved conduit was developed using a canine aortic valve. The bioprosthetic valve was fixed with glutaraldehyde and epoxy compound (Denacol-EX313/810). A vascular graft composed of ultra-fine polyester fiber (10 mm in diameter, 200 mm in length) was used. Four dogs underwent apico-aortic valved conduit (AAVC) implantation and aortic banding (bypass group, BG), while another 4 dogs underwent aortic banding without AAVC implantation (control group, CG). Cardiac catheterization and angiocardiography were performed for assessment of hemodynamics 2 weeks and 6 months after surgery. Left ventricular systolic pressure, left ventricular end-diastolic pressure and the left ventricular-aortic pressure gradient differed significantly (P<0.01) between the BG and CG dogs. Left ventricular angiocardiography showed patency of the valved conduit in all the BG dogs. Echocardiography was performed before and 2, 4 and 6 months after surgery, and showed that while pressure overload caused concentric myocardial hypertrophy in the CG dogs, the left ventricle dilated eccentrically in the BG dogs. Furthermore, relief of left ventricular pressure overload by AAVC was maintained.     

Differentiation between bovine and ovine strains of Histophilus somni based on the sequences of 16S rDNA and rpoB gene

Nucleotide sequences of 16S rDNA and rpoB gene of 25 bovine and 6 ovine Histophilus somni strains were determined to detect subtle differences between the host animal species. The 1465 nucleotide residues of the 16S rDNA exhibited levels of sequence similarities of 99.4% or more. The high sequence similarity of the 16S rDNA of recently described species H. somni was confirmed in the 31 strains from cattle and sheep. These results suggested that the intra-specific diversity of 16S rDNA was limited in bovine and ovine strains of H. somni. The specific association of strains was also observed in the 311 bp region of rpoB gene which sequence similarities were 98.6% or more. However, the phylogenetic tree analysis of the rpoB gene showed that the ovine strains appeared to form a subgroup recovered in 70% of the bootstrap trees. In the 311 bp region of the ovine strains, a HincII restriction endonuclease site was detected. The PCR-amplified rpoB DNA of 46 bovine and 20 ovine H. somni strains were examined for the digestion with HincII. As the results, 17 strains of ovine strains were cleaved by the enzyme but none of the bovine strains appeared to possess the restriction site. The restriction enzyme analysis of rpoB gene may be useful to differentiate ovine strains from bovine strains of H. somni.     

Loss of milk yield due to Akabane disease in dairy cows

Akabane disease is an infection with clinical signs of congenital malformation and abortion in ruminants. Abnormal parturitions caused by Akabane disease result in great economic loss. The purpose of this study is to estimate the reduction in the milk yield from abnormal parturition due to Akabane disease. The data were collected from 33 Holstein cows on 11 farms. The animals had abnormal parturitions during the period from September 1998 to March 1999, and were diagnosed as having Akabane disease. The mean and standard deviation of the rate of reduction in the milk yield of 33 cows after abnormal parturition caused by Akabane disease was -11.4 +/- 14.9%. The means and standard deviations of the rate of reduction of four cows calving abnormally at 220-239 days of gestation, nine cows calving abnormally at 240-270 days of gestation, and 20 cows calving abnormally at 271-300 days of gestation were -26.6 +/- 24.7%, -14.7 +/- 11.0%, and -6.9 +/- 12.3%, respectively. In this study, we demonstrated that the rate of reduction in the milk yield in cows affected by Akabane disease was -11.4 +/- 14.9%, but values as high as -26.6 +/- 24.7% were reached in the comparison with the milk yield obtained after normal parturition.     

Effects of intramammary infusions of interleukin-8 on milk protein composition and induction of acute-phase protein in cows during mammary involution

The effects of interleukin-8 (IL-8) on bovine mammary functions such as milk protein secretion and the blood-milk barrier during mammary involution were evaluated. Following the final milking, recombinant bovine (rb) IL-8 (5 or 25 microg) and a saline placebo were individually infused into the left- and right-front teat cisterns of 6 cows, respectively. Three cows without treatment at the final milking were also used as controls. Mammary secretions and blood were collected at -24, 0, 10, 24, 72, 168, 336, and 720 h after infusion. In the mammary glands infused with 25 microg of rbIL-8, the increases in somatic cell counts and in the concentrations of serum albumin, IgG1 and IgG2, and the decreases in the concentrations of alpha- and beta-casein and beta-lactoglobulin were greater than in the control glands. In the mammary glands infused with 5 microg of rbIL-8, compared to the glands infused with 25 microg of rbIL-8, these changes were moderate. These results indicate that rbIL-8 impairs the integrity of the blood-milk barrier and suppresses milk-specific protein secretions. In the cows infused with 25 microg of rbIL-8, the rectal temperature and serum haptoglobin level were transiently elevated after the infusion, showing that intramammary infusion of rbIL-8 could elicit systemic inflammation.