Circular RNAs (circRNAs) are a class of endogenous noncoding RNA, unlike linear RNAs, which form a covalently closed continuous loop by back-splicing. circRNA has no the 5′ end cap and 3′ end poly (A) tail structure, and exist steadily in many eukaryotic cells. Due to the limitation of traditional biological methods for circRNA detection in both species and abundance, circRNA is traditionally considered as the products of abnormal RNA splicing. With the development of bioinformatics and the innovation of high-throughput sequencing technology, the thousands of endogenous circRNA in mammalian cells were discovered, some of which are highly expressed in a tissue- and development stage-specific manner and display conservation across species, suggesting their potential regulating function on the gene expression. In combination with the characteristics, formation mechanism and biological function of circRNA, we summarize the research advance of circRNA in recent years, aiming to provide fundamental information for studying eukaryotic gene expression regulation and disease detection, and prospect circRNAs′ research in animal molecular breeding.

Adipocyte differentiation is a complicated process in which pluripotent mesenchymal stem cells (MSCs) differentiate into mature adipocytes. The process of adipocyte differentiation is strictly regulated by a number of transcription factors, hormones and signaling pathway molecules. In vivo and in vitro research has revealed that microRNAs (miRNAs) are also involved in adipocyte differentiation and play a role by targeting transcription factors and key signaling molecules. MAPK signaling pathway is one of important signaling systems which transduce the extracellular signal to intracellular space and cause cell response. The studies showed that, miRNAs can target certain genes in MAPK and affect its signal transduction, thus regulating adipocyte differentiation. Therefore, a summary of researches how miRNAs change the signal transduction of MAPK pathway and regulate adipocyte differentiation was performed in order to further understand the adipocyte differentiation mechanism and offer new ideas for curing the fat-associated diseases.

Inflammasomes are multiprotein complexes that induce downstream immune responses to environmental stimuli, specific pathogens and host cell damage, leading to the pyroptotic cell death of host cells. Inflammasomes mainly consist of recognition receptors of inflammatory signals ASC (the adapter apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain) and pro-caspase-1. Once activated, inflammasomes can induce the activation of caspase-1 and maturation of inflammatory cytokines, including IL-1β and IL-18. Inflammasomes can be classed into the NLR (nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3) inflammasome and the ALR (absent in melanoma 2 like receptor) inflammasome on the basis of the types of inflammatory signals recognition receptors. Host cells can recognize different viral components, including viroporins, non-structural proteins, viral double-stranded DNA and viral single stranded RNA, by different inflammatory signals recognition receptors and promote the formation of responding inflammasomes. Herein, we outlined the mechanisms of inflammasome formation activated by diverse viral components, and therefore provide a reference for future research and development of novel antiviral drugs.

 The aim of the study was to investigate polymorphism and evolution in South China chickens by the tandem repeat LEI0258 located within the B region of the chicken major histocompatibility complex (MHC-B region). Genotypes and sequences of LEI0258 were obtained from 12 Southern China chicken breeds and 2 commercial chicken breeds, and then these data were used to analyze genetic diversity and construct median-joining network. A total of 62 alleles were defined by DNA sequencing ranged from 182 to 501 bp in 580 samples, 37 of which was novel for these chicken breeds. The LEI0258 showed high levels of polymorphism in South China chickens, with 0.813, 0.960 and 0.957 for observed heterozygosity, expected heterozygosity and polymorphic information content, respectively. The Shalan, Wenchang and Wuhua Three-yellow chicken breeds had higher levels of genetic diversity than Guangxi Yellow chicken. Twenty-eight alleles of LEI0258 were corresponding to 27 available serotypes of MHC. The 62 alleles of LEI0258 were classified into 8 clusters in median-joining network, based on the SNPs and indels found within the flanking sequences, and 3 of which was found in red junglefowl, indicating that South China chicken mainly originated from red junglefowl. Some alleles existed in a certain chicken breed, which could be as a candidate marker for breed identification. The results suggest that LEI0258 can be used as a molecular marker for elucidate genetic diversity, serology and breed identification, evolution in indigenous chicken breeds.

The aim of this study was to investigate the possibility of CRTC3 gene as candidate gene for growth performance in Qinchuan cattle, and search the molecular markers related to Qinchuan cattle growth traits. PCR-RFLP method was applied to detect the polymorphisms of CRTC3 in 395 healthy Qinchuan cattle, and the association of its polymorphisms and genotype combination with growth traits of Qinchuan cattle was also analyzed. The result showed that 2 SNPs were identified, including G66478C in exon and C91297T in intron. At the G66478C locus, the cattle with genotype GC had greater body length and chest depth values than those with genotype CC(P<0.01 and P<0.05, respectively). At the C91297T locus, animals with genotype CT had greater body length, hip height, rump length and chest depth values than those with genotype TT(P < 0.01) . Animals with CC-TT had significantly greater hip height and rump length values than those with CC-CT(P < 0.01), and chest depth and chest circumference values for CC-TT were greater than CC-CT(P<0.05). Therefore, variations in the CRTC3 gene and the genotype combination CC-CT may be useful as molecular markers for growth traits in Qinchuan cattle breeding.

This study aimed to investigate the expression pattern of bbu-miR-103-1 from lactation and non-lactation periods in buffalo (Bubalus bubalis), and to predict its target gene and function. Expression pattern of bbu-miR-103-1 in lactation and non-lactation periods were detected by qRT-PCR. The precursor expression plasmid of bbu-miR-103-1 was constructed and named LpEZX-pre-miR-103-1 (HIV). It was packaged and propagated to produce high-titer lentivirus in 293T cell lines，which could be used to infect buffalo mammary epithelial cells (BMECs) and over express bbu-miR-103-1. The inhibitor of bbu-miR-103-1 was chemically synthesized and transfected into BMECs to suppress bbu-miR-103-1 at the same time. The relative expression of pantothenate kinase 3（PANK3） and milk fat metabolism related genes were detected by qRT-PCR. The results showed that the relative expression of bbu-miR-103-1 from lactation period was 5.29 times higher than that from non-lactation period in buffalo（P＜0.01）. The LpEZX-pre-miR-103-1 has been successfully constructed and packaged with the infection titer for 3.47×10⁶ PFU•mL^-1. Overexpress or suppress of bbu-miR-103-1 extremely significantly down-regulated or up-regulated（P＜0.01） the expression level of PANK3 in BMECs. Over expression of bbu-miR-103-1 extremely significantly enhanced the expression of Acetyl-CoA carboxylase alpha (ACACA), Glycerol-3-phosphate acyltransferase 1 mitochondrial (GPAM), Diacylglycerol O-acyltransferase 1(DGAT1) and Pyruvate dehydrogenase lipoamide kinase isozyme 4(PDK4) （P＜0.01），and also siginificantly up-regulated the expression of sterol regulatory element binding protein-1c(SREBP1c), Adipose differentiation-related protein（ADFP）, Cluster of differentiation 36（CD36）, Acetyl-CoA synthetase short-chain subfamily member 1（ACSS1）（P＜0.05）. Over expression of bbu-miR-103-1 down-regulated the expression of PANK3，and improved the mRNA level of SREBP1c by feedback regulation，finally promoted the de novo synthesis of fatty acid from ACACA pathway. bbu-miR-103-1 plays an important role in enhancing milk fatty acid synthesis, which provides a molecular base for revealing the mechanism of high-level milk fat content in buffalo.

The aim of the study was to clone the CDS of CCR2 gene, and to determine its expression in various tissues, which might provide basis for its functional research on regulating lipid metabolism. Each of 4 healthy, 2-3 years old castrated Jianzhou Big-eared goats and Tibetan goats were selected. After slaughter, the tissue samples from heart, liver, spleen, lung, kidney, longissimus dorsi muscle, biceps femoris muscle, triceps brachii muscle and subcutaneous fat were collected for the total protein and RNA extraction. The sequence of CCR2 gene was cloned by RT-PCR and analyzed using bioinformatics. The mRNA and protein expression of CCR2 was determined using real-time fluorescent quantitative (qPCR) and Western blot, respectively. A length of 1 186 bp cDNA of CCR2 gene was cloned, containing 1 100 bp CDS, 2 bp 5′ UTR and 74 bp 3′ UTR, encoding 370 amino acids. The goat CCR2 protein shared 97.3%, 91.9%, 77.0% and 69.2% similarity with bovine, pig, mouse and human, respectively. The goat CCR2 gene was closest associated with that of bovine, followed by pig, dog and mouse, and distant with human. The tissue expression analysis showed that expression of CCR2 was higher in kidney and heart, and lowest in subcutaneous fat and muscles in both of the goat breeds. These data indicate that CCR2 gene may play an important role in regulating lipid metabolism in goat.

Effects of embedding melatonin for Arbas Cashmere goats in telogen phase on control of cashmere growth cycle were conducted in order to extend anagen phase and increase the cashmere production. Cashmere goats were selected and randomly divided into 2 groups,each group with 3 goats（ the experiment group (T1,T2,T3) and the control group (C1,C2,C3)）. Skin tissues of the treatment and control groups were taken and tissue sections were observed for the influence of embedding melatonin on the induction of hair follicle growth. The total RNA was extracted from the 2 groups of samples and synthesized marked cDNA probes by reverse transcription, and had microarray hybridization on 8×15 K(Agilent) sheep genome-wide expression profile to screen differentially expressed genes. The results were verified by real-time fluorescent quantitative PCR technology. Histological analysis showed that embedding melatonin could obviously promote hair follicle growth. Microarray data showed that there were 95 differently expressed genes, including 61 up-regulated and 34 down-regulated. GO analysis indicated that the genes of 47.78% participated in the molecular function, those of 33.89% were involved in biological processes, and those of 18.33% were associated with the composition of cell. Compared with the control groups, differential expression of related genes in treatment groups were involved in the hair follicle morphogenesis and biological processes of surrounding skin appendages. These differently expressed genes provide valuable reference to research Cashmere goat hair follicle growth and the function of the cyclical controlling genes.

 In this study, we used Solexa sequencing to screen and analyze the differentially expressed microRNAs (miRNAs) of Anhuai goat pituitary tissues in the follicular phase (Fols) and luteal phase (Luts), and explore the role of pituitary at post-transcriptional level of Fols to Luts transition occurred in goats. In total, 11 319 069 and 11 432 846 raw reads were obtained from the ovaries of Anhuai goats in Fols and Luts, respectively, after eliminating impurity, 11 162 888 and 11 016 138 clean reads. 147 known miRNAs were co-expressed in the two different periods phases, 148 and 150 known miRNAs were expressed in the ovary in the Fols and Luts, respectively. In addition, 27 novel miRNAs were co-expressed in the two phases, 52 and 95 novel miRNAs were expressed in the ovary in the Fols and Luts, respectively. Let-7f was the highest expressed significantly different known miRNAs in the two phases, and miR-159 was the highest expressed significantly different novel miRNAs in the two phases, which may participate in the follicular-luteal transition of Anhuai goats. In the KEGG pathway analysis, ko00511, ko00052, ko01100, ko00030 and ko00520 may be related to the synthesis of sex hormones. The study succeeded to construct the expression library of miRNAs which were abundant and differentially expressed in Anhuai goat pituitary tissues. The results will help to further understand the role of miRNAs which regulates secretion of hormone participate in goat pituitary. And some identified miRNAs will help to further understand the role of miRNAs in the regulation of follicular to luteal transition in goat ovaries.

This experiment was conducted to investigate the effect of wine grape pomace supplementation to base diet on reproductive performance and antioxidant ability of testis in ram. A total of thirty 5-month-old with average weight of (25±1) kg Dorper (♂) × Small Tail Han sheep (♀) F1 male lambs were randomly selected and divided into 5 groups equally. To establish a stress model, lambs in one of groups were raised freely, while the other 4 groups were confined in stall. Lambs raised freely were fed with a base diet without grape pomace, and other lambs were fed with diets supplemented with grape pomace at 0%, 5%, 10%, 20%, respectively. The experiment lasted for 80 d. At the end of experiment, all lambs were slaughtered and sampled. Testis coefficient, epididymal sperm indicators, antioxidant levels of testis were analyzed, and moreover, expression of Cu/ZnSOD, CAT, GPx4, Nrf2 mRNA and protein in testis were detected. The results showed that, compared with free group, MDA and ROS level of testis significantly increased (P<0.01), testis weight of lambs significantly decreased (P<0.05), and the organ coefficient of testis had a trend to be lower (P=0.06) in confined group with 0% wine grape pomace; epididymal sperm density, acrosomal integrity and motility were lower (P<0.05 and P<0.01, respectively), while epididymal sperm deformity higher (P<0.01), in confined group with 0% wine grape pomace than those in free group. These results showed that ram raised in confined condition could cause oxidative stress and affect the reproductive performance. However, compared with confined group with 0% wine grape pomace, epididymal sperm density and motility were higher, while deformity lower, in wine grape pomace-added groups (P<0.05). MDA level of testis significantly decreased (P<0.01), but SOD, CAT and GSH-Px activity significantly increased (P<0.01,P<0.05 and P<0.01) in wine grape pomace-added groups. Furthermore, the mRNA expression of Cu-ZnSOD and protein expression of Cu-ZnSOD, GPx4 and CAT in testis significantly increased (P<0.05) in wine grape pomace-added groups. The results indicate that wine grape pomace can enhance antioxidant capacity in testis and improve the reproductive performance of separated-raising lambs.

The aim of this study was to investigate the relationship of ROS, developmental block and pioglitazone as an antioxidant. The experiment was divided into 3 groups：Control group, H₂O₂ group and H₂O₂+PIO group. The oxidative damage model of mouse embryos induced by H₂O₂ was established and treated with or without pioglitazone. The ROS level after treatment with pioglitazone was measured by DCHF-DA and the expression of maternal effect genes and zygotic genes were analyzed by Semi-quantitative reverse transcription PCR. The results showed that: (1) the ROS level of H₂O₂group was significantly higher than control group and H₂O₂+PIO group in both 1-cell and 2-cell embryos (P＜0.05); (2) the rate of 2-cell to 4-cell transition in H₂O₂ group was significantly lower than control group and H₂O₂+PIO group (P＜0.05), while the difference of 1-cell to 2-cell transition rate among the groups was not significant (P＞0.05)；(3) the expression of maternal effect genes (Hsf1,Zfp3612,Zp3) and zygotic genes (Eif1-α,Muerv-L,Zscan4d) in H₂O₂ group was lower than control group and H₂O₂+PIO group (P＜0.05). The results provided a clear molecular aspect regarding the mechanism by which pioglitazone promoted embryos development and overcome 2-cell block.

The objective of the present study was to investigate the effect of in ovo feeding of beta-hydroxy-beta-methylbutyrate (HMB) on hatchability, growth performance and skeletal muscle development in broilers. A total of 540 fertilized eggs from Arbor Acre broilers were allotted into 3 treatments: one control group (without injection), and two injection groups injected with 1 mL 0.9% saline (saline group) and 1 mL 0.1% HMB (HMB group) at 7 d of incubation, respectively. After hatching, 72 healthy male chicks were selected from each treatment and randomly divided into 6 replicates with 12 birds each. The results showed that: 1) In ovo feeding had no significant effect on hatchability of fertilized eggs (P>0.05). 2) Compared with the other groups, HMB injection significantly increased the BW of broiler at hatch and 21 d posthatch and markedly elevated ADG during the first 21 days (P<0.05). 3) At 7 d of age, breast muscle percentage of chicks from HMB injection group were increased by 1.01% than that of chicks from saline group (P=0.019). In ovo feeding HMB significantly increased breast muscle percentage of broilers by 1.11% (P<0.05) than the control group and by 1.04% (P<0.05) than the saline injection group at 21 d of age. 4) The abdominal fat percentage of chicks from HMB injection group was the lowest, and significantly lower than that of chicks from the control group at 21 d of age (P=0.018). 5) Compared with the control group and saline group, chicks from HMB injection group had significantly higher myofiber diameter at hatch and 4 d of age (P<0.05). 6) At hatch and 7 d of age, the mitotic activity of satellite cells in breast muscle in chicks from HMB group were significantly higher than that from other groups (P<0.05). 7) At 7 d of age, plasma Insulin-like growth factor-1 (IGF-1) content in HMB injection group was significantly higher than that in the control group (P<0.05), while there was no significant difference between HMB and the saline groups (P>0.05). In ovo feeding HMB may improve BW at hatch, increase mitotic activity of satellite cells and IGF-1 content in the blood circulation, thus facilitating the breast muscle development and promoting the growth in the early period. In ovo feeding HMB did not affect hatchability and feed conversion ratio in broilers. Growth performance was not different between the control and saline injection groups.

The experiment was conducted to evaluate the feasibility for establishing the prediction model of the dietary metabolizable energy (ME) of compound feeds of sheep by using proximate anlaysis measurements or digestible nutrients. Sixty-six castrated Dorper × Thin-tailed Han crossbred rams ((49.6±1.3) kg of body weight) were randomly assigned into 11 groups(one basal diet group and 10 experimental diet groups). Digestibility trials were conducted to measure and calculate individual digestible energy (DE) and ME, establishing the metabolic energy and proximate nutrients and digestible nutrient prediction model with the linear regression method. The results indicated that: the OM and GE digestibility of diets were significantly related to CP, NDF, ADF and GE (P<0.01); CP digestibility was significantly related to CP, NDF and ADF (P<0.01), and significantly related to OM (P<0.05); NDF and ADF digestibility were significantly related to GE and CP (P<0.01). NDF digestibility was significantly related to OM and NDF (P<0.05). The prediction equation of dietary ME using proximate analysis measurements was ME (MJ•kg^-1)=38.881 － 19.516ADF (%)－ 28.672OM (%) (R ² = 0.640, n=60, P<0.01); The prediction equation of dietary ME using digestible nutrients was ME (MJ•kg^-1) = 1.613DE (MJ•kg^-1)－14.705DOM (%) + 2.743DNDF (%)－ 3.179 (R ²=0.879, n=60, P<0.01). In conclusion, there were significant correlations between proximate nutrients, digestible nutrients and ME. The prediction model of proximate nutrients and digestible nutrients can be used in routine analysis.

 The objective of this study was to research the effects of diet energy and protein levels on the mRNA expression of peroxisome proliferator-activated receptor γ(PPARγ) and fatty acid binding protein 4(FABP4) in the adipose tissues of Tan sheep. A total of 112(56♂,56♀) healthy Tan sheep with similar body weight were selected and allocated randomly to 4 groups(4 replicates in each group, and 7 sheep in each replicate). 3 stages(22-28, 29-35, 36-40 kg) was classified, and standard diets for each stage were designed according to body weight and expected daily gain in sheep feeding standard of NY/T(816-2004), 4 diets with energy and protein levels of 0.84×Standard(group I), 0.96×Standard(group II), 1.08×Standard(group III), 1.20×Standard(group IV) were assigned to feed sheep in each group, respectively. At the end of each stage, one sheep from each replicate was slaughtered, and samples of tail fat, perirenal fat and subcutaneous fat were collected for analyzing the mRNA expression of PPARγ and FABP4 by Real-time quantitative PCR. The results showed as follows: In tail fat, PPARγ and FABP4 mRNA expression levels was significantly higher in group II than other groups at the end of stage 22-28 and 36-40 kg(P<0.05); FABP4 mRNA expression levels was highest in group II, and lowest in group IV at the end of stage 29-35 kg(P<0.05). In perirenal fat, PPARγ mRNA expression levels was significnatly higher in group II, and significantly lower in group IV compared with group III at the end of 3 stages(P<0.05). FABP4 mRNA expression levels was higher in group II and III at the end of stage 22-28 kg(P<0.05); FABP4 mRNA expression levels was higher in group II compared with group IV at the end of stage 29-35 kg(P<0.05); FABP4 mRNA expression levels was higher in group I and II at the end of stage 36-40 kg(P<0.05). In subcutaneous fat, there was no significant difference between different groups at the end of 3 stages(P>0.05). These results indicated that the effect of diet energy and protein levels on PPARγ and FABP4 mRNA expression was greater in deep fat tissue(perirenal fat) than that in superficial fat tissue(subcutaneous fat) in Tan sheep. The diets with different energy and protein levels had an effect on PPARγ and FABP4 mRNA expression of tail fat in Tan sheep.

As a transporter, protein encoded by potD is involved in the binding and transportation of polyamine, which is necessary for the growth of cells. In some pathogens, the protein is identified as a virulence-associated factor, but of which the function is still unclear in Haemophilus parasuis. A potD mutant strain SC1401ΔpotD::kan was constructed by the natural transformation method. The growth curve, the ability of autoagglutination and biofilm formation, serum resistance ability and the virulence to mice of the parental strain SC1401 and potD mutant strain were measured. No significant difference was observed between the parental and mutant strains in the growth curve and the ability of autoagglutination and biofilm formation. However the potD mutant strain showed an obvious decrease in serum resistance ability and the virulence to mice. The findings above suggested that potD gene may be associated with virulence in H. parasuis.

In the present study, Marc-145cell lines with stable expression of shRNA were established by lentiviral expression system to inhibit replication of porcine reproductive and respiratory syndrome virus (PRRSV), and its interference suppression effect to PRRSV key target genes was clarified from the level of cell model. LR recombination reaction between pENTR/U6/Nsp9-4 (pENTR/U6/Nsp9-6, or pENTR/U6/-CON, respectively) and pDEST were done by using the LR technology to obtain expression skeleton. Expression vector and auxiliary plasmid Vira PowerTM Packaging Mix were cotransfected into 293-FT cells by Lipofectamine 2000, respectively, to gain Lentiviral supernate and to infect Marc-145 cells. After 48 h, the cells were incubated in standard culture medium including blasticidin (3.3 μg•mL^－1), colonies with blasticidin were obtained when cells were cultured in selection medium within 14 d, monoclonal were expanded, passaged, screened to get monoclonal cell lines. The integration of the obtained monoclonal cell lines were identified by PCR, CPE observation and TCID₅₀ determination, and the inhibition effect of the cell lines with shRNA to PRRSV proliferation were detected by indirect immunofluorescence test and real-time PCR methods. pENTR/U6/Nsp9-4, pENTR/U6/Nsp9-6 and Marc/pU6-CON had been integrated into the chromosome of Marc-145 cells and expressed stably at high level. Results showed that the shRNA expressed by two cells with pEN/U6/Nsp9-4, pEN/U6/Nsp9-6 specifically suppressed PRRSV proliferation, respectively. The infection rates of PRRSV to the negative control and normal cells were higher than those to the recombinant Marc/pU6/NSP9-4 and Marc/pU6/NSP9-6, and the difference was obvious. These results demonstrate that Marc/pU6/NSP9-4 and Marc/pU6/NSP9-6 cell lines can effectively express shRNA to inhibit the replication and proliferation of PRRSV. It helps to clarify the key target genes that suppress PRRSV replication, and is expected to construct transgenic animals based on the siRNA targeted PRRSV.

Nanoparticle-assisted polymerase chain reaction (nanoPCR) is a novel method for the rapid amplification of DNA. This study was aimed to establish a simple and sensitive nanoPCR assay for detection of Aleutian mink disease virus (AMDV), primers were designed based on the conserved region of the NS1 gene sequences available in GenBank to amplify a 365 bp fragment. The optimized annealing temperature and the concentration of gold nanoparticles were studied. Whether or not the DNA replication fidelity compromised in nanoparticla-assisted PCR was detected by sequencing nanoPCR products. A nanoPCR assay was developed and its sensitivity and specificity were investigated. Under the optimized conditions of nanoPCR assay, annealing temperature was 51℃ but that of conventional PCR was 55 ℃. The best concentration of gold nanoparticles was in the range of 0.2-0.8 nmol•L^-1. The 99% homology between the products obtained with the nanoPCR amplification and the conventional PCR showed that highly levels of DNA replication fidelity in this nanoPCR. In addition, the other mink viruses detected by the nanoPCR were all negative. Under the optimized conditions of the AMDV nanoPCR assay, the nanoPCR assay was 10-fold more sensitive than a conventional PCR assay in urine and feces samples. The lower detection limit of the nanoPCR assay was about 4.0×102 copies. Furthermore, a total of 40 clinical samples were detected by this assay. The results showed that the nanoPCR is sensitive than counter immunoelectrophoresis (CIEP). The nanoPCR assay developed in this study can be applied widely in clinical diagnosis the urine and feces and field surveillance of AMDV-infection.

Four cellulose-degrading rumen bacteria strains were isolated from Mongolia sheep. The four strains bacteria were identified and numbered as H1, H2, N1 and N2. The growth characteristics and cellulase activity were measured to provide experimental material for subsequent experiments. Bacterial morphological, physiological and biochemical characterization, DNA sequence homology analysis were used for identification of isolated strains. Growth curve of strains were measured by using spectrophotometer. Filter paper enzyme activity, CMCase activity, salicin enzyme activity and microcrystalline cellulose enzyme activity of four strains of cellulolytic bacteria were measured by using reducing sugar method. Two strains of bacteria H1, H2 were identified as Ruminococcus flavefaciens and N1, N2 were Streptococcus. The growth curves of four strains showed that lag phase of H1, H2, N1, N2 were 3-4 h and the maximum cell concentration of H1, H2 appeared in 28 h and N1, N2 appeared in 14 h. Four strains of bacteria had high activity of filter paper enzyme. The activity of filter paper enzyme, CMCase and microcrystalline cellulose enzyme were significantly higher for H2 than for H1, N1 and N2 (P＜0.05). Filter paper enzyme activity of H1 was 0.08 μmol•(mL•min ) ^-1 and was lowest among four strains. Four strains bacteria with cellulose enzyme activity were isolated by using the method of roll tube technique. These four cellulolytic bacteria strains can be used for subsequent study.

 The experiment was conducted to study on the effects of subclinical doses of neomycin sulfate on the ileal mucosa-associated microbiota (MAM) composition and dynamic change of broiler chickens at 1 to 42 days old.Chicken ileal segments were collected in group A (basal diet) and B (basal diet with 50 mg•kg^-1 Neomycin Sulfate)，and MAM DNA were extracted at day 1，7，14，21，28，35 and 42，respectively.The community of the ileal MAM between two groups were analyzed by Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE)at various ages，and the random clone library of 16S rDNA V3 region of the MAM in ileum at 42 days old between Group A and D was established by analysis of 16S rDNA gene sequences.DGGE profiles showed that the structure of the MAM in ileum between the two groups were of remarkable difference during day 1-28，and the similarity of the MAM in ileum was 40%-60%.The alterations of MAM of ileum were remarkably different between the two groups during day 1-35，with 9%-33% change in group A and 17%-45% change in group D.Analysis of the library in ileum indicated that nine operational taxonomic units (OTUs) (form 94 gene sequences or clones) were detected in the group A，as compared with 6 OTUs (form 93 clones) in the group D.Exiguobacterium and Lactobacillus were predominant in the group A and D，counting for 48.94%，38.30% and 45.16%，49.46%， respectively.The amount of other species found in ileum in group A were different from that in group D.In addition，sequence known being related to Colibacillus were not detected in group A and D.These results indicated that the composition and diversity of the MAM in ileum at day 42 does exist difference between group A and D，especially the proportion of Lactobacillus，these difference might be caused by the continuous antibiotic pressure selection.

The objective of this study was to investigate the changes of α-smooth muscle actin (α-SMA), collagen type I and collagen type III in liver of broilers with ascites syndrome (AS) and the prevention and treatment of the compound recipe of the traditional Chinese medicine (TCM) on AS. A total of 309 7-day-old Ross broilers were randomly divided into six groups, group None was bred with normal diet, the rest were bred with high-energy diet derived from standard diet added with 3% lard and 4% fish meal and 0.12% Na+ in drinking water at 9-11 ℃ to induce AS, group Control was given no medicine, compound recipe of the TCM groups (High, Middle, Low) were respectively given a dose of 2, 1, 0.5 mL•kg^-1 of the TCM in drinking water, and group L-Arg with 1% L-arginine in diet. The results showed that at 15, 25, 35 and 45 days of age, compared with group None, the incidence of AS, ascites heart index, heart index, lung index, liver index, the levels of α-SMA, collagen type I and collagen type III in liver of broilers in group Control were increased significantly (P<0.01 or P<0.05), and spleen index in group Control was decreased significantly (P<0.01 or P<0.05). Compared with group Control, the items above were all improved in compound recipe of the traditional Chinese medicine groups and group L-Arg (P<0.01 or P<0.05). The study showed the increases of the levels of α-SMA, collagen type I and collagen type III in liver of broilers participated in the pathogenesis of AS. The studied compound recipe of the traditional Chinese medicine with the role of tonifying qi-blood and activating qi to excrete water can prevent and treat AS of broilers effectively, and the mechanism was related to the decreases of compound recipe of the traditional Chinese medicine on the levels of α-SMA, collagen type I and collagen type III in liver of broilers with AS.

The aim of this study was to take the Streptococcus suis (S. suis) 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) as a drug target, and provide theoretical and experimental basis for the development of novel antibiotics for the prevention and treatment of S. suis infection. In this experiment, S. suis HMGR was prokaryotically expressed and purified by Ni-NTA agrose. Its enzyme activity was determined by spectrophotometric method. In addition, a multiple sequence alignment of HMGR was performed by CLUSTALW to identify conserved domains. Homology modeling of the three-dimensional (3D) structure of S. suis HMGR was performed by SWISS-MODEL. The quality of the model was evaluated by PROCHECK. The result of enzyme activity analyses showed that optimal reaction conditions of S. suis HMGR was pH 5.0 and 37 ℃, the Vmax and Km value was 846 U•mg^-1 and 0.213 mmol•L^－1 respectively. The analysis of SWISS-MODEL showed that crystal structure of Streptococcus pneumonia HMGR was the appropriate template for homology modeling of S. suis HMGR. The theoretic model of 3D structure of S. suis HMGR was proven to be reliable through quality assessment. The S. suis HMGR model will contribute to virtual screening of novel antibacterial agents against S. suis infection. Enzyme activity assay provides a feasible method for validation of effective inhibitors against S. suis HMGR in biochemical experiment.