Meat quality is one of the most important factors for determining the efficiency of broiler production. Recently, two newly reported myopathies are gaining the more attention of poultry industry globally for their high incidence, white striping (WS) and wooden breast (WB). WS is characterized by the occurrence of white fat striations parallel to muscle fibers, while WB is mainly characterized by obvious hardening of the breast muscle. These two myopathies share similar histological lesions, and often appear together. The occurrence of the two myopathies can adversely affect meat's appearance, nutrition value and ability for further processes, which result in huge economic loss to the industry. In recent years, the study of characteristics and mechanism of WB and WS has a greater progress. Most of the studies were reported by foreign research groups, fewer by Chinese research teams. In this review, we summarized the research progress of WB and WS from the aspect of pathological features, effect on meat quality and nutrition value, and detailed mechanism in order to provide reference and theoretical basis for future studies.

Exosomes are vesicles secreted by various cells, containing proteins, lipids and nucleic acids, and have effects in signal transduction, immune regulation, metabolite management and coagulation. Exosomes are important media in information transfer between parasites and hosts. Parasites can transfer biological active substances into host cells, regulate immune responses by secreting exosomes. Exosomes can serve as drug carriers to block the transfer of parasites into host cells and enhance the immunity of host, so they provide a new opportunity for the prevention and treatment of parasitic diseases, break the frequent use of chemical synthetic drugs in livestock production, reduce drug residues, improve the quality and safety of animal products. This article reviews the formation, composition and the effects of exosomes derived from different parasites, in order to lay the foundation for the diagnosis and treatment of parasitic diseases.

The aim of this study was to explore the candidate genes and signal pathways affecting muscle fiber characteristics. In this study, muscle fiber diameter and density of longissimus dorsi of Mashen and Large White pigs aged 6 months were measured by HE staining, and the gene expressions in longissimus dorsi of the 2 pig breeds at 6 months old was detected by using RNA-Seq. GO and KEGG enrichment analysis were used to study the function of differentially expressed genes(DEGs). The accuracy of RNA-Seq results was verified by qRT-PCR. The results showed that the fiber diameter of longissimus dorsi of Mashen pig was significantly shorter than that of Large White pig (P<0.01), and the fiber density of Mashen pig was greater than that of Large White pig (P<0.01). A total of 105 DEGs at least 2-fold change were identified, including 55 up-regulated genes and 50 down-regulated genes in longissimus dorsi of Mashen pig compared to Large White pig. GO enrichment analysis showed that the DEGs were mainly enriched in the cellular component related to mitochondrion and skeletal muscle differentiation biological processes, and KEGG analysis showed that these DEGs were mainly involved in the signaling pathways related to oxidative phosphorylation. The expression trends of 6 selected DEGs detected by qRT-PCR and RNA-Seq were the same, which indicated that the results of RNA-Seq were accurate and reliable. Based on the results of expression abundance, GO and KEGG analysis of DEGs, the genes of MYL3, MYH3 and MYH6 were found to affect muscle fiber characteristic by influencing the composition of muscle fiber. ND6 gene was related to muscle fiber type by involving in oxidative phosphorylation pathway in mitochondria. MICU2 gene was involved in keeping homeostasis of Ca²⁺ concentration in mitochondria and further affected cellular function. The genes of EGR1 and FOS coding transcription factors might affect muscle growth and development by regulating cell proliferation, differentiation and apoptosis. This study preliminarily explored the reason causing significantly different muscle fiber characteristics between Mashen and Large White pigs, and provided a theoretical basis for improving meat quality in pig production.

The aim of this study was to further elucidate the roles of GnIH and VIP genes in sheep seasonal estrus and reproductive regulation. Adult Sunite sheep (SNT) under short photoperiod and long photoperiod and Small Tail Han sheep (STH) at follicular stage and luteal stage were selected, meanwhile SNT at 21th day of short photoperiod and 3rd, 15th, 21th, 42th, 49th days of long photoperiod were selected, respectively. Gonadal axis tissue samples including hypothalamus, pituitary, pineal body, ovary, oviduct, uterine body were collected in 3 sheep for each reproductive stage. The qPCR method was used to analyze the expression characteristics of GnIH and VIP genes. The results showed that GnIH and VIP genes were expressed in the above 6 tissues, and had a high expression level in hypothalamus tissue of two breeds (SNT and STH). Expression level of two genes under long photoperiod (LP) was extremely significantly higher than that under short photoperiod (SP) in hypothalamus of SNT (P<0.01). Expression level of VIP gene was significantly higher at luteal stage than that at follicular stage (P<0.05), and expression level of GnIH gene was slightly higher at luteal stage than that at follicular stage but the difference was not significant (P>0.05) in hypothalamus of STH. When SP turned into LP, expression levels of two genes in hypothalamus of SNT rose and showed a transient peak at LP 3rd day, then the expression decreased. Quantitative expression characteristics of GnIH and VIP genes in gonadal axis tissues of adult sheep were revealed in this study. Additionally, expression pattern of the 2 genes in hypothalamus under different photoperiods and different reproduction stages further implied that GnIH and VIP genes was involved in the regulation of sheep seasonal estrus and transition of estrous stages. When SP turns into LP, the 2 genes play pivotal role in the first 3 days under LP.

This study was conducted to estimate the genetic parameters of cervical vertebrae and thoracic vertebrae related traits of ducks, in order to provide a reference for future duck breeding for neck and breast meat yield of Pekin duck. 405 ducks (50 males and 355 females) from the F2 resource population of Pekin duck×mallards were used as research materials for genetic parameters estimation with MTDFREML program. Traits including cervical vertebrae number (CVN), thoracic vertebrae number (TVN), body length(BL), body weight (BW), neck length (NL), neck weight (NW), neck circumference (NC), NL/BL, neck weight percentage (NWP), keel length (KL), breast meat weight (BMW) and breast meat weight percentage (BMWP) were detected and analyzed after slaughtered at 49 weeks of age. The results showed that cervical and thoracic vertebrae number variations were different in different duck populations. The heritability estimated for CVN, TVN, BL, BW, NL, NW, NC, NL/BL, NWP, KL, BMW and BMWP were 0.08, 0.65, 0.49, 0.47, 0.36, 0.45, 0.38, 0.18, 0.43, 0.55, 0.40 and 0.48, respectively. CVN had significant genetic and phenotypic correlation with NL (0.40 and 0.29), NW (0.13 and 0.17) and NWP (0.23 and 0.19). CVN significantly affected NW, NL and NWP(P<0.05). In contrast with CVN, TVN showed no significant genetic and phenotypic correlations with KL (0.01 and 0.05) and BMWP (0.03 and -0.05). KL and BMWP of ducks with different TVN both showed no significant difference(P>0.05). The genetic and phenotypic correlations of KL with BMW (0.72 and 0.49) and BMWP (0.11 and 0.32) were positive and significant. In conclusion, there existed cervical and thoracic vertebrae number variation in duck populations. Selection on cervical vertebrae number could improve the neck yield indirectly, while selection on thoracic vertebrae number could not increase the yield of the breast meat. Besides that, the study also verified that the selection on keel length could improve breast meat yield.

This study aimed to investigate the genetic laws of the variables related to the original mid-infrared spectrometry (MIRS) of cow milk. DHI, mid-infrared spectral data and pedigree data were obtained from 1 822 Holstein dairy cows owned by farm of Beijing Sunlon Livestock Development Co., Ltd. Principal component analysis and genetic parameter estimation were performed using the R language (v3.51), SAS (v9.2) and DMU (v6.0), the animal model used for genetic parameter estimation taken into account the fixed effects including the testing months, parity and days in milk and random effects including additive genetic effect and permanent environmental effect. The results showed that the correlation coefficient among more than 80% of the wavenumbers of mid-infrared spectrometry ranged from 0.500 to 1.000, and the variation coefficients of the wavenumbers in region 3 574-3 521 cm^-1 and 3 630-3 618 cm^-1 were higher. The heritability of the most wavenumbers of MIRS data were mostly between 0.010 and 0.030, and the proportion of wavenumbers with medium and high heritabilities was about 7%. With the increase of heritability, the absorption increased, the transmittance and CV decreased. The genetic law of milk components can be better understood through the genetic analysis of the original MIRS data obtained from DHI samples, in order to improve the quality of milk and provide reference for cattle breeding.

The aim of this study was to explore the the miRNA expression profile in muscle tissues at different ages of yak and analyze their biological characteristics to explore their regulation patterns during yak muscle development. Four small RNA libraries of muscle tissues during 0.5-year-old, 2.5-year-old, 4.5-year-old and 7.5-year-old of yak were constructed and sequenced using Solexa technology. The sequencing results were verified and analyzed by RT-qPCR and bioinformatics methods. The expression profile of each miRNA in 4 age groups were obtained. Fifty eight miRNAs were differentially expressed in muscle tissues during the 7.5-year-old of yak compared with other 3 age groups, of which 53 miRNAs were significantly down-regulated and 5 were significantly up-regulated in 7.5-year-old muscle tissue. GO enrichment and KEGG analysis were performed using R language, 58 miRNAs might be involved in the regulation of proliferation and differentiation of yak muscle cells through PI3K-Akt,MAPK, Ras and the regulation of actin cytoskeleton signaling pathways. PI3K-Akt, MAPK and Ras signaling pathways jointly targeted 53 target genes, which indicated that the 3 signaling pathways were related to each other. Furthermore, the RT-qPCR results showed that the expression tendency of 7 of the 8 randomly selected miRNAs were consistent with the sequencing results. The results indicate that yak muscle development may be regulated by multiple miRNAs and involve in multiple signaling pathways, which may help to construct the regulatory network of miRNAs in muscle tissue, which lays a theoretical foundation for further study the miRNA regulating the mammalian muscle development.

This study aimed to explore serum differential proteins in cows with inactive ovaries using iTRAQ technology. The Holstein cows in a intensive dairy farm were determined for energy balance (EB) status by blood β-hydroxybutyric acid (BHBA), and were assigned into inactive ovaries groups (IO, n=50), normal estrus control group (CON, n=50) at 60 to 90 day postpartum by the estrus manifestation, rectal examination and B-ultrasound examination.The isotope-labeled absolute quantification (iTRAQ)/mass spectrometry (MS) combined technique were used to screen differentially expressed proteins,Western blot and ELISA methods were used to identify differentially expressed proteins in serum of dairy cows with inactive ovaries. The results showed that 61 differentially expressed proteins were obtained,GO analysis showed that the biological process consisted of 34 annotations, the molecular function consisted of 15 annotations, the cellular composition consisted of 13 annotations. A total of 57 nodes were obtained from the analysis of protein network interaction. 68 proteins interpreted each other, protein interactions were enriched P<10^-16, 11 signal metabolic pathways were obtained. After screening, it were found that glycolysis/gluconeogenesis, amino acid biosynthesis,glucagon signaling pathway, vitamin digestion and absorption might be related to the occurrence of ovarian quiescence.A total of 14 differentially expressed proteins verified by Western blot and ELISA were associated with inactive ovaries:GPX3, SCGB1D and PKM2 were down-regulated;ADIPOQ, AHSG, APOA4, FETUB, ALDOB, SPAM1, LDHB, RBP4, IGFBP2, ITIH3 and GLYCAM1 were up-regulated.ADIPOQ, IGFBP2 and RBP4 affect follicular development by affecting reproductive hormone biological processes, GPX3 affects follicular development through oxidative stress.

The purpose of this study was to investigate changes in proteome expression and screen key regulatory proteins during bovine follicular development, and protein components of GCs(granulesa cells)were analyzed by label-free quantitative proteomics technology.DF(dominant follicles)and SF(subordinate follicles)during the bovine estrous cycle were collected, GCs were separated, total proteins were extracted, proteins were digested with trypsin and analyzed by LC-MS/MS, the expression of proteins in DF and SF were analyzed after database retrieval, and key regulatory proteins were screened by bioinformatics method. In this study, 3 409 proteins were successfully identified from 30 321 peptide fragments (FDR ≤ 0.01), of which 2 895 were DF proteins and 3 102 were SF proteins, 259 differentially expressed proteins were identified (Fold change>2,P<0.05), 17 differential expressed proteins might be related to the process of bovine follicular dominance, and SERPINB2 might regulate bovine follicular atresia.The results enriched the studies on DF and SF proteome and laid a foundation for further studies on follicular atresia and dominance theory by identify differential expressed proteins and specific expression proteins.

This study was conducted to investigate the effects of maternal exposure to BPA on testicular development of male offspring mice. Eight-week-old SPF female mice weighing 18-22 g were randomly divided into 7 groups (group A, B, C, D, E, F and G) with 4 replicates in each group, 5 per replicate. Group A was given normal distilled water daily, and group B was given 0.05 mg·kg^-1 BPA daily, group C was given 0.5 mg·kg^-1 BPA daily, group D was given 5 mg·kg^-1 BPA daily, group E was given 10 mg·kg^-1 BPA daily, group F was given 20 mg·kg^-1 BPA daily, group G was given 50 mg·kg^-1 BPA daily. F0 female mice were exposed to BPA from pregnancy day 1 to the lactation day 21. F1 male mice were sacrificed for sampling at weaning (21 d). The results showed that the BPA content in the serum and testis of the male offspring mice significantly increased when the dose of BPA was more than 5 mg·kg^-1 (P<0.05). The dose of BPA greater than or equal to 20 mg·kg^-1 resulted in a significant increase in testicular index in male offspring mice (P<0.05). H&E staining showed that the testicular tubules shrunk and the small tube gap became larger when the dose of BPA was greater than or equal to 10 mg·kg^-1. The results of comet assay showed that the damage of testicular DNA significantly increased in the progeny testis DNA when the BPA exposure dose was greater than or equal to 5 mg·kg^-1 (P<0.05). The results of immunohistochemistry showed that the expression of androgen receptor (AR) in the testes of the offspring significantly decreased when the dose of BPA was greater than or equal to 20 mg·kg^-1 (P<0.05). Transcriptome sequencing showed that the expression of Snrnp40 encoding U5 snRNA subunit up-regulated in spliceosome pathway, and the expression of Hnrnpu encoding splicing universal protein component down-regulated, which led to the first steps of mRNA post-transcriptional modification were blocked in male offspring mice when the dose of BPA was 50 mg·kg^-1. The results of the real-time PCR were consistent with those of the transcriptome sequencing. The result indicate that female mice exposing to low doses of BPA can cause testicular dysplasia of male offspring mice, and its molecular mechanism may be related to the hindered reaction of the first step of mRNA post-transcriptional modification.

This study was conducted to investigate the effects of early feeding on the morphology of rumen and small intestine of 20-60 day-old goat kids and to explore the relationship between rumen and small intestine morphological development. This experiment was based on a single factor design with the feeding strategy as the experimental factor. Seventy-two Haimen goat kids of 20 days of age with similar body weight were randomly divided into 3 treatments with 6 replicates in each treatment and 4 kids in each replicate. Goat kids were fed with milk replacer (MRO group), milk replacer+concentrate (MRC group), milk replacer+concentrate+alfalfa pellets (MCA group), respectively. The experiment lasted for 40 days after a 3-d adaptation period. Growth performance and nutrients apparent digestibility were determined during the trial. Slaughter experiment was carried out to determine the morphology of the rumen and small intestine on 60 days of age of the goat kids. The results showed that:1) During the 20-60 days of age, the dry matter and crude protein intake of goat kids in MRO group were significantly lower than those in MCA and MRC groups(P<0.05). But the apparent digestibility of dry matter and crude protein of goat kids in MRO group were significantly higher than that in MCA and MRC groups(P<0.05). 2) The rumen papilla length and width of goat kids in MCA group were significantly higher than those in MRO group(P<0.05). The length of rumen papilla of goat kids in MRC group was significantly higher than that in MRO group (P<0.05). 3) The crypt depth of duodenal of goat kids in MCA group was significantly greater than that in MRO group(P<0.05), while the V/C value was significantly lower in MCA group compared with MRO group(P<0.05). Compared with MCA group, the jejunal crypt depth of goat kids in MRC and MRO groups were significantly decreased (P<0.05), but the V/C values were significantly increased (P<0.05). The ileal V/C values of goat kids in MRC and MCA groups were significantly decreased compared with MRO group (P<0.05). 4) The papilla length, papilla width and epithelial thickness of rumen, and the crypt depth of jejunum and ileum were positively significantly cor-related with digestible dry matter intake and digestible protein intake(P<0.05), whereas the V/C values of duodenum and ileum were negatively significantly correlated with digestible dry matter intake and digestible protein intake(P<0.05). The digestible NDF intake was negatively sig-nificantly correlated with the thickness of the rumen keratin layer(P<0.05), whereas positively significantly correlated with rumen muscle layer thickness(P<0.05). Rumen papilla length and width were positively significantly correlated with digestible NFC intake(P<0.05), whereas the V/C values of the duodenum and ileum were negatively significantly correlated with digestible NFC intake(P<0.05). Early feeding is beneficial to the development of the rumen morphology, but it may slow the development of the small intestine because of the reduced apparent digestibility of nutrients in concentrate pellets or alfalfa pellets compared with milk replacer.

The change of C2C12 cells exposed to H₂O₂ was investigated and the possible path of oxidative damage was explored in this study. There was 3 treatments, and 6 repeats in each treatment. C2C12 cells attached to the substrate and cultured in DMEM for 24 h were treated as control (n=6); the medium was added with PDTC (20 μmol·L^-1, PDTC treatment, n=6) for 24 h or H₂O₂ (0.5 mmol·L^-1, H₂O₂ treatment, n=6) for 24 h. The viability, ROS level and apoptosis rate of cells in different treatments were detected. The expression of genes related to cell apoptosis and autophagy and factors related to NF-κB signaling pathway were determined by real-time PCR and Western blot. The results showed that cells in PDTC treatment had significantly higher total apoptosis rate, mRNA expression of caspase-3, caspase-6, caspase-9 and the protein expression of total caspase-3, mRNA expression of Beclin1, LC3-Ⅱ/LC3-I and the protein expression level of total LC3-Ⅱ(P<0.05), and had significantly lower mRNA expression of p50, Bcl-2, RelA, Cox-2 and protein expression of total NF-κB compared to that in the control treatment(P<0.05). Moreover, cells in H₂O₂ treatment exhibited significantly higher ROS level and total apoptosis rate(P<0.05), mRNA expression of caspase-3, caspase-6, caspase-8, caspase-9 and protein expression of total caspase-3(P<0.05), mRNA expression of Beclin 1, LC3-Ⅱ/LC3-I and protein expression of total LC3-Ⅱ(P<0.05), mRNA expression of Bax(P<0.05), and had significantly lower mRNA expressions of p50, Bcl-2, RelA, Cox-1, Cox-2 and protein expression of total NF-κB(P<0.05) compared to that in the control treatment. These results indicated that H₂O₂ could promote the ROS formation, mediated the apoptosis and autophagy processes by suppressing the NF-κB signaling pathway in C2C12 cells, which was similar with the role of PDTC, the inhibitor of NF-κB factor.

As one of the most important Alphaherpesvirus, Marek's disease virus (MDV) causes immunosuppression and rapid-onset of T-cell lymphoma in its natural host chicken, namely Marek's disease (MD). A large number of viral microRNAs (miRNAs) have been identified in the MDV genomes, which may play critical roles in virus replication, latency, and tumourigenesis. It has been previously confirmed that deletion of miR-M11-5p from the viral genome significantly enhances MDV pathogenicity and oncogenicity, suggesting that it may be a tumor suppressor during MDV tumourigenesis. To further reveal the regulatory mechanism mediated by miR-M11-5p in MDV oncogenesis, we have presently performed a hybrid-PCR to amplify the candidate host target genes using the cDNA derived from chicken embryo fibroblasts (CEF) cellular RNA as template. The PCR products were ligated into the pMD19-T vector and transformed into E. coli JM109 to construct a cDNA library for screening the candidate targets for miR-M4-5p. Based on PCR identification, DNA sequencing and BLAST analysis, a total of 77 candidate genes were obtained, of which 37 binding sites recognized by miR-M11-5p were located in the 3'-UTRs of the mRNA genes. The further analysis of dual luciferase reporter assay (DLRA), miRNA over-expression and RT-qPCR confirmed that three host genes (MAFB, LOC776816 and RFX7) were the final target genes for miR-M11-5p. Our data provide an important foundation for further elucidation of the regulatory mechanism mediated by miR-M11-5p in MDV tumourigenesis.

This experiment was conducted to study the pathogenicity and genome variation of broiler reovirus isolates in Shandong Province. In 2017, a virus was isolated from commercial broilers with tarsal joint swelling and severe bleeding in Weifang, Shandong, and identified by RT-PCR and electron microscopy. And the virus was returned to commercial broilers. The whole genome of the isolated strain was amplified by using18 pairs of primers, then sequenced, and its genetic evolution was analyzed. Serum cross neutralization test was carried out between the isolated strain and the classical strain S1133. Our results showed that a strain of avian reovirus (named WF17) was isolated. The clinical symptoms could be completely replicated in commercial broilers and the virus could be re-isolated from experimental chickens. The genome of the isolate fully conformed to the genomic structure of avian reovirus. And the main antigen (σC protein) gene was closest to 918 strain from Taiwan Province, with 92.7% homology, and 55.9% homology with S1133 strain. The antigen-related index (R value) between WF17 strain and S1133 strain was only 0.19. At present, commercialized vaccine based on S1133 strain can not effectively protect variant avian reovirus strains.

Bovine norovirus (BNoV) is a pathogen causing calf diarrhea and has been detected in 19 countries. The aims of this study were to investigate the prevalence and molecular characteristics of the virus in several regions of China. In this study, a total of 93 diarrheic fecal samples and 54 healthy fecal samples collected from 12 farms in 5 provinces were detected by RT-PCR. The results showed that the detection rate of BNoV in diarrhea samples (25.81%) was significantly higher than that of the healthy samples (9.26%) (P<0.01), which proved that the virus was associated with calf diarrhea. Phylogenetic analysis based on 29 RdRp sequences (partial polymerase sequences) showed that 5 strains clustered into GⅢ.1 and the remaining 24 strains clustered into GⅢ.2. Phylogenetic analysis based on 18 partial VP1 and 13 VP2 sequences showed that BNoV strains in China present a unique evolutionary. These results indicated that, as an emerging pathogen with unique evolutionary characteristics in China, BNoV has been widely circulated among dairy calves, providing an important reference for the prevention and control of calf diarrhea in China.

In this study, we established a Chinese Hamster Ovary (CHO-K1) cell line stably expressing PCV2-Cap, and identified the immunogenicity of the protein and prepared for a kind of novel subunit vaccine against porcine circovirus. Firstly, we constructed the recombinant plasmid pEE12.4-PCV2-Cap. Then we transfected adherent CHO-K1 cells with the plasmid. To obtain the monoclonal cell line, the transfected cells were selected with the methods of pressurized screening and limited dilution. And then the monoclonal cell was optimized for growth in suspension and cultured in fed-batch mode for the quality evaluation. The cell strain was fermented, and the purified target protein was verified by immunoassay in mice. The results demonstrated that PCV2-Cap protein was correctly expressed by CHO-K1 cells. The maximum density of living cells reached 6×10⁶ per milliliter, the cell viability was more than 80% in the process of the culture, the PCV2-Cap production can get to 370 mg·L^-1. The results of ELISA showed that Cap protein produced by CHO-K1 has good immunogenicity. A CHO-K1 cell line stably expressing PCV2-Cap protein has been established, and the immunogenicity analysis of the target protein was further carried out. It lays a foundation for the development of new porcine circovirus subunit vaccine.

The aim of this study was to understand the genotypical characteristics of swine P. mul-tocida currently circulating in China. Capsular genotyping, LPS genotyping, MLST genotyping were performed on P. multocida isolates from the clinical samples including lungs, nasal swabs, tracheas, livers, and other tissues of pigs with respiratory disorders in different farms in different regions of mainland China; virulence genotyping based on the detection of different virulence gene profiles was also set for the isolates recovered herein. The results showed that the capsular genotypes of the swine P. multocida currently circulating in China were A (48.85%), D (42.75%), and F (2.67%); the LPS genotypes were L3 (25.00%) and L6 (75.00%); the MLST genotypes were ST3 (21.25%), ST10 (27.50%), ST11 (42.50%), ST12 (2.50%), ST16 (2.50%), ST74 (1.25%), and ST75 (2.50%). When combining the capsular genotypes with the LPS genotypes and the MLST genotypes, it was found that the predominant capsule:LPS:MLST genotypes prevalent in pigs in China were A:L3:ST3 (20.00%), A:L6:ST10 (26.25%), and D:L6:ST11 (42.50%). During the virulence genotyping, some virulence-associated genes were found to show a certain level of "genotype-preference", which means the detection rate of those genes in some genotypes is significantly higher than their detection in other genotypes. These results indicate that a capsule:LPS:MLST genotype D:L6:ST11 of P. multocida is likely to be strongly associated with swine respiratory disease in China.

To investigate the function of lipoic acid metabolic enzymes in vivo, an Escherichia coli (E. coli) model was established.△lplA△lipB~DH5α mutant strain was obtained with deletion of lplA and lipB genes from DH5α strain using the Red homologous recombination system. The lplA and lipB genes were cloned into the expression vector of pBAD322G and transformed to the △lplA△lipB~DH5α mutant strain to construct the complementary strains of ClplA-△lplA△lipB~DH5α and ClipB-△lplA△lipB~DH5α. The lipoate modification on the substrates in the mutant and supplemented strains were analyzed with Western blot, mass spectrometric analysis and complementation experiment. The mutant strain △lplA△lipB~DH5α was very stable in the culture and displayed the phenotype of lplA and lipB deletion. Supplemented strain ClipB-△lplA△lipB~DH5α can grow in the M9 medium with glycerol as carbon source, ClplA-△lplA△lipB~DH5α can grow when LA is added to this medium. These results indicated that the E. coli model without lipoate modification function was successfully established. It will facilitate the functional study of enzymes associated with lipoic acid modification in other microorganism.

The aim of this study was to explore whether spleen tyrosine kinase (Syk) is involved in the expression of β-defensin-1 (SBD-1) in ovine ruminal epithelial cells (ORECs) induced by Saccharomyces cerevisiae Mannan (S.c M). Firstly, the expression of Syk in rumen tissues and ORECs was detected by immunohistochemistry, RT-PCR and immunofluorescence. Then, qPCR and Western blot were used to detect the expression of Syk after S.c M stimulation of ORECs, and the phosphorylation level of Syk was detected by Western blot. The ORECs were transfected with three Syk-specific siRNAs (#1, #2 and #3) for 24 h, qPCR was used to detect the expression of Syk mRNA, and the Syk siRNA with the best interference effect was screened. Finally, after treatment of ORECs with the best siRNA and Syk specific inhibitor R406, the expression of SBD-1 was detected by qPCR and ELISA to determine the role of Syk in the expression of SBD-1 induced by S.c M. The results showed that Syk was expressed in ORECs, and the expression level of Syk mRNA and protein were significantly higher in mannan-stimulated ORECs than in unstimulated group (P<0.05). After S.c M stimulation of ORECs for different time (5, 15, 30, 45 and 60 min), Syk was phosphorylated, and the phosphorylation level reached the maximum after 15 min stimulation (P<0.01). In addition, the expression of Syk was decreased after Syk's three specific siRNAs transfected with ORECs, and the inhibitory effect of Syk siRNA#2 was the most significant (P<0.01). Simultaneously, Syk siRNA#2 and R406 significantly reduced S.c M-induced ORECs. Expression of SBD-1 (P<0.01). The above results indicate that Syk is involved in the expression of SBD-1 induced by S.c M.

This experiment was conducted to investigate the nerve toxicological effects of medulla oblongata tissues induced by deoxynivalenol (DON), through the changes of lipid peroxidation, neurotransmitter secretion and calcium homeostasis. Thirty weaned piglets (21 days old) were randomly divided into control group, low-dose and high-dose DON groups, with 10 piglets in each group. The piglets in control group were fed with basal diet, and DON low-dose group and high-dose group were fed with DON diet containing 1 and 2 mg·kg^-1 DON, respectively. The trial was conducted for 60 days. At the end of the experiment, five piglets were randomly selected from each group for slaughter. The medulla oblongata tissue was collected to detect the activities of oxidation and antioxidation indexes, neurotransmitter and Ca²⁺ concentrations, the relative expression of calmodulin (CaM) and calmodulin-dependent kinase Ⅱ (CaMK Ⅱ) mRNA, and the protein expression levels of CaM, CaMKⅡ and p-CaMKⅡ were measured. Compared with the control group, the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in medulla oblongata of piglets in high and low doses of DON group decreased significantly (P<0.01), while the concentration of nitric oxide (NO) increased significantly (P<0.01). The concentration of serotonin (5-HT) in high and low doses of DON group were significantly increased (P<0.01),while the concentration of acetylcholine (ACH) was significantly decreased (P<0.01). The concentration of dopamine (DA) and gamma-aminobutyric acid (GABA) in high doses of DON group were significantly decreased (P<0.05).The concentrations of Ca²⁺ in high and low doses of DON group were significantly increased (P<0.01).The relative expression of CaM mRNA in low doses of DON group were significantly decreased (P<0.05), the expression of CaMKⅡ mRNA in high and low doses of DON group were significantly decreased (P<0.01),the expression level of CaM protein in high doses of DON group was significantly decreased (P<0.01), while the expression of p-CaMKⅡ protein was significantly increased (P<0.01). These results suggest that DON exposure can change the lipid peroxidation reaction and the secretions of neurotransmitters and neuronal calcium homeostasis in medulla oblongata tissues of weaned piglets. It suggests that DON has some neurotoxic effects in piglets.

The present study was conducted to investigate the effects of acute exposure to bacterial lipopolysaccharide (LPS) on testis and its function in mice. Healthy male mice were randomly divided into 4 groups:Control group, 1.25 mg·kg^-1 LPS group, 2.5 mg·kg^-1 LPS group and 5.0 mg·kg^-1 LPS. The control group was intraperitoneally injected with 200 μL saline, while the other three groups were injected the same volume saline containing different doses of LPS and treated for 12 hours. Testes were collected to check the pathological changes after staining; body weight, testicular and epididymal indexes were recorded and the related sperm quality indexes were determined; testosterone (T) level in serum was measured by ELISA; Transcription of inflammatory genes (TNF-α, IL-6, GAS6 and TGF-β1) were detected by RT-qPCR. The results showed that LPS acute exposure reduced the body weight of mice in a dose-dependent manner (P<0.05 or P<0.01), significantly decreased testicular index (P<0.05 or P<0.01), sperm density (P<0.01) and sperm motility (P<0.05 or P<0.01), and increased the rate of sperm malformation (P<0.05 or P<0.01). Meanwhile, LPS exposure resulted in testicular pathological changes to varying degrees, such as spermatogenic cell apoptosis, enlargement of seminiferous duct cavity and less sperms, and significantly reduced the levels of testosterone (T) in serum. In addition, LPS also increased the transcription of pro-inflammatory factors (TNF-α and IL-6) and inhibited anti-inflammatory factors (GAS6 and TGF-β1) in a dose-dependent manner. These results indicated that acute exposure to bacterial LPS impairs testicular tissue and leads to spermatogenesis disorder via destroying the balance of inflammatory factors in the body.

To analyze genetic variation of feline panleukopenia virus (FPLV), in this study, a fecal sample was collected from a cat infected FPLV in Beijing and was used to isolate FPLV by CRFK cells, and identified by hemagglutination assay (HA), molecular biology. The results showed that cytopathic effects could be observed in CRFK cells. The diameter of virus particle about 25 nm was observed by electron microscope. The HA blood coagulation rate was 1:256. The full genome was cloned, sequenced and analyzed. The results showed that the isolated virus had a genome of 5 118 bp, phylogenetic tree of VP2 showed that FPLV BJ04 strain and KX434462 strain were on the same small branch. The isolated virus, according to VP2 gene homology analysis, shared from 99.1% to 99.5% homology with reference strains, and NS1 gene shared from 99.0% to 99.5%. Animal regression test results also suggested that clinical symptoms and pathological changes were observed in the challenge group. In this study, an epidemic strain of FPLV in Beijing was successfully isolated, and the genetic variation of VP2 and NS1 gene were analyzed. The results provide basic information for the better prevention and control of FPLV.