Pig （Sus scrofa） fat accumulation can be reduced by feeding with high dosages of clenbuterol, but the molecular mechanism has not yet been explained. In our study, a porcine cDNA microarray representing 3 358 pig genes was successfully developed. This microarray is the first porcine DNA microarray in China and its false positive rate is 0.98%, which means the microarray platform is reliable. The microarray can be used to study gene expression profiles in multiple pig tissues because the present genes percentage of adipose, skeletal muscle, heart, liver, lung, kidney, and spleen were all more than 60%. This microarray was used to identify the genes responding to clenbuterol stimulation in pig internal organs, including heart, liver, lung, spleen, and kidney. Many genes were identified including enzymes involved in lipids metabolism （lipoprotein lipase up-regulated in liver, heart and lung, ATP-citrate lyase and carnitine palmitoyltransferase II precursor up-regulated in liver, succinyl-CoA up-regulated in lung, mitochondrial malate dehydrogenase down-regulated in spleen）, and signaling pathway genes （cAMP-protein kinase A signaling pathway was found up-regulated in liver, heart, lung, and kidney as reported previously, while transforming growth factor was found down-regulated in heart and lung）. However, no common gene responding to clenbuterol administration was found in all tissues. The expression levels of 14 genes were analyzed using real-time PCR with 82.1% of them induced to express similar magnitudes as in the microarray analyses. This work offers some understanding of how clenbuterol so effectively reduces pig adipose accumulation on the molecular level.
[ Objective ] This study aimed to identify Streptococcus agalactiae and lay the foundation for the prevention and control of mastiffs in dairy cows. [ Method] Ten strains were isolated from milk samples produced by diseased dairy cows suffering from mastitis for morphologic observation, culture characteristic investigation, biochemical identification and Lancefield grouping. The isolated strains were identified at the molecular level by nested-PCR. [ Result] Among the ten isolates, six strains were 13-hemolytic and Gram-positive on blood agar, belonging to Lancefield group B, which were identified as Streptococcus agalactiae by biochemical identification and nested-PCR. After overnight incubation, the coincidence rate between results of nested-PCR detection and biochemical identification reached 100%. [ Conclusion ] Bacterial incubation, rapid DNA extraction and specific PCR can provide basis for early epidemiological survey of Streptococcus agalactiae infection in cattle.
Yanying ZHANGGuisheng GAOZhengben LIGuangping GAOQiumei SHIXinhua SHAOYinju LIANGHuiran LIU
