Little is known about the distribution of Rhodococcus equi in the soil environment of native horses in China. One hundred and eight soil samples were collected from native-horse farms in the Hulun Beier grasslands of eastern Mongolia, the Xilin Goler grasslands of southern Mongolia, and Tongliao city in Inner Mongolia of China for investigating the distribution of R. equi in these regions. The isolation rates of R. equi from soil samples from the Hulun Beier and Xilin Goler grasslands ranged from 25.9% to 30.0%. In contrast, isolation rates from soil samples from Tongliao city was as high as 82.3% and the mean number of R. equi in soil samples from Tongliao city was 10 times more than those of samples from the grasslands. The 488 isolates were examined using PCR for the presence of genes that encode virulence-associated 15 000-17 000 antigen protein (VapA) and the 20 000 antigen protein (VapB). All isolates were negative for virulence-associated proteins. Plasmid profiles of these avirulent isolates showed that cryptic plasmids of various sizes were present with an incidence of 13.3% to 21.5%. The results of the present study contrast with those of our recent study, in which we reported that R. equi was absent from Mongolian horses in Ulaanbaatar, Mongolia. It is suggested that the difference between the results of these two studies is due to the mobile pasturing system in Mongolia and nonmobile pasturing system in Inner Mongolia.

Sixty barrows (Duroc × Labdrace × Yorkshine) were randomly assigned to two groups by weight of 33 kg,each of which was replicated three times with ten pigs. Half of the pigs were fed with diets containing 10 mg/kg lead and 0.5% particulate montmorillonite,the other half pigs were fed only with diets supplemented 10 mg/kg lead as control groups for 100 days.The results showed that the addition of particulate montmorillonite to the diet significantly decreased lead concentration in tissues such as blood,brain,liver,bone,kidney and hair and enhanced the erythropoiesis as measured by increasing numbers of RBC,hemoglobin and hematocrit values ,and elevated ALA-D activity in liver. The damage of lead to the liver was evident in the increases in hepatic concentration of malondialdehyde (+ 17.08% );decreases in the antioxidant enzymes catalase(-85.73 % ),superoxide dismutase ( - 52.17% ) and glutathione peroxidase ( - 47.56% ). Concomitant use of particulate montmorillonite in the diets completely ameliorated the lead-induced oxidative damage. It indicated that particulate montmorillonite is possessed of the potential therapeutic activity against lead poison.

The experiment was conducted to examine the effect of zinc toxicity on the peripheral blood T-lymphocyte by the method of flow cytometry(FCM) and ANAE.200 one-day-old Avian broilers were divided into four groups,and fed with the diets as follows:①control group(Zn 100 mg/kg diet) and ② zinc toxic groups(Zn 1 500 mg/kg diet,zinc toxic group Ⅰ;Zn 2 000 mg/kg diet,zinc toxic group Ⅱ;Zn 2 500 mg/kg diet,zinc toxic group Ⅲ) for seven weeks.The ANAE positive ratios of the peripheral blood T-lymphocytes were much lower in the three zinc toxic groups than that in control group at 7 weeks of age.CD4+ T cell numbers were reduced from 2 to 7 weekds of age in zinc toxic group Ⅲ and from 6 to 7 weeks of age in zinc toxic group Ⅱ,as compared with that of control group.The numbers of CD8+ T cell decreased at 2 and 4 weeks of age in zinc toxic groups Ⅱ and Ⅲ,and at 7 weeks of age in zinc grups Ⅰ and Ⅲ.CD4+/CD8+ ratio was higher at 2 and 4 weeks age,and lower at 6 and 7 weeks of age in zinc toxic groups Ⅰ,Ⅱ and Ⅲ than in control group.The results showed that zinc toxicity would suppress the development of T-lymphocytes and reduce the peripheral blood T-lymphocyte populations.Potential mechanism underlying these observations are also discussed.

The experiment was conducted to examine the effect of copper toxicity on the peripheral blood T-lymphocyte using the flow cytometry(FCM) and ANAE.180 one-day-old Avian broilers were divided randomly into three groups,and fed diets as follows:(1)Controls(Cu 11.97 mg/kg diet) and (2)copper toxic(Cu 650 mg/kg diet,copper toxic group Ⅰ;Cu 850 mg/kg diet,copper toxic group Ⅱ) for six weeks.The ANAE positive ratios of the peripheral blood T-lymphocytes were much lower in the two copper toxic groups than in control group from 1 to 6 weeks of age(P＜0.05 or P＜0.01).Also,there was significant difference between copper toxic groups Ⅰ and Ⅱ at 1,3,5 and 6 weeks of age(P＜0.05 or P＜0.01).CD+4 T cell numbers reduced from 2 to 6 weeks of age in both copper toxic group Ⅰ and copper toxic group Ⅱ as compared with those of control group(P＜0.05 or P＜0.01).At the same time,there was significant difference between copper toxic groups Ⅰ and Ⅱ at 6 weeks of age(P＜0.05).But the numbers of CD+8 T cell were not varied from 2 to 6 weeks of age in copper toxic groups Ⅰ and Ⅱ in comparison with those of control group(P＞0.05).The CD+4/CD+8 ratio was lower from 2 to 6 weeks of age in copper toxic groups Ⅰ and Ⅱ than in control group.The results showed that copper toxicity could suppress the development of T-lymphocytes and reduce the peripheral blood T-lymphocyte populations.Potential mechanisms underlying these observations are also discussed.

Hapten-carrier protein conjugates were made using ciprofloxacin (CPFX) and two carrier proteins by 1-ethyl-3-(3- dimethylaminopropyl)-carbodiimide hydrochloride (EDC) method. Ultraviolet spectrophotometry were used to demonstrated that the molecule conjugate ratio of CPFX to ovalbumin (OVA) and bovine serum albumin (BSA) are 6:1 and 13:1 respectively. Nondenaturing gel electrophoresis results revealed that the conjugate band migrates differently from that of the carrier protein alone and of the EDC-treated protein when as few as 6 molecules of CPFX are attached to the carrier protein. The results indicate that nondenaturing gel electrophoresis and ultraviolet spectrophotometry can be employed to analyze the molecule coupling ratio of CPFX to carrier proteins qualitatively and quantitatively.

The susceptibility to 9 kinds of antibiotics of 393 animal pathogenic E. coli isolated from clinical samples was determined from 2000 to 2003. The resistance to TC, GM, CMP, AMP, RA, KM, FT, SM and CIP were 93.89%, 57.76%,78.63%, 77.86%, 92.11% ,47.33%, 46.82%, 76.84% and 74.81%, respectively. The isolates could be classified into eight classes according to the number of drugs to which srains were resistant. The resistance spectrum of the isolates varied from 2to 9 kinds of the above drugs. The strains that were resistant to seven kinds of drugs were more than 80 percent. The resistance rates of swine origin strains to GM,AMP and KM were higher than those of poultry origin strains, while the resistance rates of poultry origin strains to TC, CMP, SM and CIP were higher remarkably than those of swine origins. The frequency of resistance increased from 2000 to 2003,which was from 67.33% to 90.58% for CMP, 71.29% to 84.81% for AMP, 73.76%to 80.10% for SM and 61.88% to 88.48% for CIP. At the same time, the resistance rate of GM decreased from 61.39% to 53.92%. Thirty-seven strains (95 %) could make all the Kunming mice die within 72 h injected intraperitoneally with the culmice three times in vivo. The pathogenicity of wild strains with drug resistance acquired naturaly to mice did not decline.

The Interleukin-2 gene cDNA was cloned into the Pichia pastoris expression vector pPICZB,which is under the control of the alcohol oxidase promoter AOX1. The linearized recombinant plasmid of BoIL2-pPICZB,digested by Sac I ,was transformed into X-33 strains by electroporation. The multi-copy insert transformants were screened by Zeocin-resistance and induced by 1% methanol. The intracellular expression products were tested by SDS-PAGE analysis and Western blotting. Purified recombinant BoIL2 was gained by metal-chelating affinity chromatographic (MCAC). Assay with murine CTLL-2 cells showed that the recombinant BoIL2 exhibited the biological activity.

In present study,comparisons were carried out to develop and improve in vitro mauration(IVM) systems of goat oocytes. Oocytes were cultured in TCM-199 supplemented with(1)10% sera (either estrous goat serum (EGS) or fetal bovine serum(FBS)) + 20 mg/L luteinizing hormone (LH) + 10 mg/L follicle stimulating hormone (FSH) + 1 mg/L estradiol (E2); (2)10% EGS with different gonadotropins(LH: FSH) at a concentration of 5 mg/L: 0.5 mg/L or at 20 mg/L: 10 mg/L with0. 075 IU/mL human menopausal gonadotropin(HMG),1 mg/L estradiol 17β; (3)10% EGS+ 0. 075 mg/L HMG+10-20 μg/EGF. The culture was also performed by M199 supplemented with 10% EGS+0. 075 mg/L HMG+ 10-20 μg/L EGF into ultra-filtrated water which was derived either from self-producing or from purchased for use. The oocytes were cultured at 38 ℃,5% CO2 in air for 24 h,and the meterphase Ⅱ stage oocytes were examined under dissecting microscope. The results showed that EGS was better than FBS in supporting goat oocyte IVM. An addition of HMG in M199 could improve oocyte maturation and induce a higher percentage of metaphase Ⅱ oocytes compared to gonadotropins. 10-20 μg/L EGF improved goat oocyte maturation but the influence was not significant. Fresh,high quality water was vital for oocyte IVM. In conclusion,under our conditions with IVM ,the best result in maturation of goat oocyte has been M199 supplemented with 10% EGS+0.075 IU/mL HMG+10-20 μg/L EGF and prepared in fresh purified water.

150-day-old Tianfu ducklings were divided into three groups,and fed with diets as follows :Zn deficient (22. 9 mgZn per kg diet),controls(100 mg Zn per kg diet) and Zn toxic (1 300 mg Zn per kg diet) for seven weeks (Zn deficiency,ZD)or four weeks (Zn toxieity,ZT). The ANAE+ positive ratios of the peripheral blood T-lymphocytes were much lower (P＜0.01 ) in Zn deficient and toxic groups than in the control group. The results showed that Zn deficiency and toxicity would suppress the development of T-lymphocytes and reduce the peripheral blood T-lymphocyte populations. Potential mechanisms underlying these observations are also discussed.

Porcine endogenous retroviruses (PERV) can infect human cell in vitro, which raised widely concerns re-garding the transmission of PERV to xenograft recipients. It's essential to establish a method for detection of PERV.3 pairs of primers were synthesized according to the sequence of gag, pol and env gene of PERV. Polymerase chainreaction (PCR) and reverse transcription PCR (RT-PCR) assays were performed for detection of PERV provirusDNA and PERV specific mRNA. The results showed that provirus DNA and mRNA of PERV existed and expressedin all 4 tested cell lines. The sizes of amplified fragments are identical with the predicted. These methods may be suit-able for monitoring PERV in other cells or tissue.