Characteristics of the intestinal flora of specific pathogen free chickens with age.

Specific pathogen-free (SPF) experimental animals are recognized as standard laboratory animals in the fields of biomedical, animal husbandry and veterinary research and production. Intestinal flora plays a critical role in nutrient absorption, improving health and protecting the host from pathogens. We therefore explored the variation and maintenance of intestinal flora in SPF chicks in order to better understand the composition of intestinal microflorain SPF chickens, and provide reference for the study of intestinal flora of SPF experimental animals. Five chicks were randomly selected at each of 14, 28, and 42 days, and ceca were removed for DNA extraction. The Illumina Miseq platform was used for microbiome analysis of the V3-V4 region of the 16S rRNA gene. During the course of chick gut microbiome development, we observed major changes in diversity, especially between day 14 and day 28. Firmicutes, Proteobacteria, and Bacteroidetes were the main bacterial taxa, and Firmicutes increased significantly with age. The genus with the highest relative abundance was Lactobacillus, followed by Faecalibacterium. In addition, while abundance of Ruminococcaceae spp., Ruminococcus, and Blautia increased with age, Lactobacillus, Enterobacteriaceae spp., and Oscillospira decreased with age. Interestingly, the abundance of Faecalibacterium first increased and then decreased over time. The characteristics of SPF chicken gut flora at different ages establish a basis for the regulation of intestinal flora in the early stage of brooding, and also provide a theoretical foundation for controlling and preventing infections and poultry diseases in newborn chickens.

Isolation,identifiation and epidemiological analysis of swine Streptococcus in the northeast region of China / 中国兽医学报

In order to know that Streptococcus exist in health swine herd,2 204 cases of nose swabs were collected in swine from different areas in Dongbei three province of northeast China.Seed swab to Streptococcus culture medium,24 hours after culturing,gram staining with becteria culture,gram positive Streptococcus were identified with PCR technology,then farther identified serotype with Streptococcus suis 1,2,7,9 serotype special primers.The results showed that Streptococcus exist rate in swine herd of Heilongjiang,Jinlin,Liaoning is 29 %,27 %,34 %,respectively.PCR typing assay indicated that 155 strains of Streptococcus suis were isolated including 7 strains of 1 serotype,39 strains of 2 serotype,4 strains of 7 serotype,11 strains of 9 serotype,94 strains of other serotype in three province of northeast China.

Molecular Cloning of Two Novel Temporins From Lithobates catesbeianus and Studying of Their Antimicrobial Mechanisms / 生物化学与生物物理进展

Temporins are a kind of small,hydrophobic and C-terminus amidated antimicrobial peptides from Rana species.They are effective against bacteria,fungi,yeast,protozoa and viruses.Two novel temporins named as temporin-La(LLRHWKILEKYLanifc) and temporin-Lb(LFRHVVKIFEK.Ylamid.) were cloned from Lithobates catesbeianus.Synthetic peptides of temporin-La and temporin-Lb showed strong antimicrobial activities against bacteria tested,especially Gram-positive bacteria.Besides,temporin-La showed no haemolytic activity to rabbit erythrocytes at the concentration of 250 mg/L while temporin-Lb showed weak haemolytic activity(LC50≈ 230 μmol/L).Transmission electron microscopy showed that temporin-La and temporin-Lb induced different effects on bacterial structure of Staphylococcus aureus.

Antibiotic Sensitivity Detection and Analysis of Escherichia coli Isolated Clinically in China / 中国兽医学报

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.