Acute infection of encephalomyocarditis (EMC) virus in Syrian hamsters.

One-month-old Syrian hamsters of the APA and Std: golden strains were inoculated intraperitoneally with 10(5) PFU/head of the D variant of encephalomyocarditis (EMC) virus and examined virologically and pathologically up to 7 days after inoculation. APA hamsters developed apparent hyperglycemia due to pancreatic islet cell damage while Std:golden hamsters did not. Hamsters of both strains showed clear histopathologic changes in the testis with prominent viral replication as well as in the brain, heart and exocrine pancreas. The susceptibility to EMC virus-infection was higher in males than in females and in APA than in Std: golden hamsters.     

Immunogenic properties and mycoplasmal pneumonia of swine (MPS) lung lesions in Large White pigs selected for higher peripheral blood immune capacity

Immunogenic properties and mycoplasmal pneumonia of swine (MPS) lung lesions were compared between the immunity‐selected Large White line and the non‐selected Large White line. The selected Large White line showed a higher level of pulmonary MPS lesions compared with the non‐selected Large White line. Subsequent to vaccination, the percentage of natural killer cells and T cells (CD3⁺CD4⁺CD8^‐ and CD3⁺CD4^?CD8⁺ T cells) were significantly increased in the non‐selected line but remained unchanged in the immunity‐selected Large White line. Secretion of Mycoplasma hyopneumoniae vaccine‐specific immunoblogulin G and phagocyte activity in peripheral blood were significantly higher in the immunity‐selected Large White line than in the non‐selected line. Expression of interleukin (IL)‐4 and IL‐6 messenger RNA in hilar lymph nodes was significantly lower in the immunity‐selected Large White line than in the non‐selected line. However, expression of IL‐10 in all immune tissues was significantly higher in the immunity‐selected Large White line. These results suggest that the selection for high immunity was not effective in increasing resistance to MPS lung lesions.     

Lesions in the central nervous system of DBA/2 mice infected with the D variant of encephalomyocarditis virus (EMC-D).

The central nervous system (CNS) of DBA/2 mice inoculated i.p. with the D variant of encephalomyocarditis virus (EMC-D) (10(3) PFU/head) was examined up to 28 days postinoculation (28 DPI). The virus titer of CNS reached a maximum level at 4 DPI, and infectious viruses became undetectable by 28 DPI. Histopathologically, degeneration of neurons with virus antigens was observed in St. pyramidale hippocampi, Nuc. amigdaloideus corticalis and St. granulosum cerebelli of the brain and in Cornu ventrale of the thoracic to lumbar spinal cord at 6 DPI. In addition, in the spinal cord, demyelination was found in Funiculus ventralis and Funiculus lateralis at 6 DPI and it progressed to form spongiosis at 10 DPI. In correspondence with these virological and histopathological findings, hind limb paralysis developed in some mice at 6 DPI, and its incidence increased markedly to about 60% at 10 DPI.     

Production of transgenic rabbits using centrifuged pronuclear zygotes

Superovulation of female rabbits was induced by subcutaneous injection(s) of porcine FSH. Zygotes were recovered 17 to 19 hr after hCG injection and were classified into two categories under a microscope equipped with Nomarski interference-contrast optics at x 200 magnification: (A) zygotes with clearly visible pronuclei, or (B) zygotes with visualized pronuclei after 10 min centrifugation at 12,000 x g. No significant difference between strains was found in the proportion of category-A zygotes (JW 72.6% vs NZW 79.3%). Pronuclei of category-A zygotes were located in the center of the cytoplasm, and the pronuclei of category-B zygotes were slightly moved by centrifugation toward the mass of cytoplasmic lipid droplets. Exogenous DNA solution (5 microg/ml of fusion gene composed of bovine alphaS1-casein promoter and human growth hormone structural gene) was microinjected into the pronucleus of the JW zygotes. The pronucleus of category-A zygotes with a mean volume of 7.4 pl swelled up to 16.6 pl (132% increase), while that of category-B zygotes with a mean volume of 6.1 pl swelled up to 15.9 pl (148% increase). Nevertheless, similar proportions of category-A and category-B zygotes developed into offspring after transfer to recipient females (11.1 and 11.2%, respectively). The efficiency to produce hGH-carrying transgenic rabbits was 0.9% (2/235) from category-A zygotes and 0.5% (1/215) from category-B zygotes (P>0.05). To date, transgenic rabbits have been produced without centrifugation of pronuclear zygotes. However approximately 25% of fertilized rabbit zygotes can be used for DNA microinjection after they have been centrifuged to visualize their pronuclei.     

产糖化酶的类芽孢杆菌S3菌株的多相分类鉴定

本研究从甘薯种植地、淀粉厂厂区及下水道等有机质丰富的地方采取土样,从中分离产糖化酶细菌.其中一株命名为S3的分离菌株,根据形态特征观察、生理生化性状检测、全细胞脂肪酸成分分析、16S rDNA序列分析DNA-DNA杂交等鉴定实验结果表明属于类芽孢杆菌属(Paenibacillus).根据16S rDNA序列构建的系统发育树,与S3进化距离相近的类芽孢杆菌菌种分别为:P.curdlanolyticus、P.kobensis和Paenibacillus sp.PALXIL08.但是,S3菌株在生理生化特征及细胞脂肪酸成分含量等都与这3种菌有所不同;DNA-DNA杂交实验表明S3和这3种菌的同源性分别为37.8％、21.7％和29.4％.因此,S3菌株可能是类芽孢杆菌的一个新种.     

Supplementation of various meals to fish meal diet for chum salmon fry

In a 6-week feeding experiment, chum salmon, Oncorhynchus keta, swim-up fry, were fed fish meal diets supplemented with silkworm pupae powder (5%), dried beef liver (5%), krill meal (5%) or earthworm powder (5%) at the expense of fish meal, or substituting glucose (13%) for dextrin. Fish fed the diet with earthworm powder showed the best growth performance (675% weight gain in 6 weeks) and feed efficiency (117%). The growth rate and feed efficiency of the krill meal group were also significantly better than those of the control group (without supplement or substitution). Substitution of glucose and supplementation of silkworm pupae or beef liver failed to improve the growth rate, but significantly improved feed efficiency. Food consumption of fish fed the diet supplemented with earthworms was lowest, and none of the dietary treatments appreciably increased food intake of the fish over that of the control group. The dietary group receiving earthworm powder also showed significantly higher body fat content than the remaining dietary groups. No significant differences were noted in body protein and ash contents among all dietary treatments.