To investigate the distribution and biological characteristics of Trueperella pyogenes in caprine mastitis,67 milk samples from were collected from goats with mastitis in 9 dairy goat farms in the Guanzhong area of Shaanxi Province.A total of 21 strains of T.pyogenes were isolated through bacterial separation and culture.PCR amplification was conducted for 8 virulence genes of the 21 isolated strains,and the susceptibility of the strains to 10 antimicrobial drugs was tested u-sing the micro broth dilution method.Nine selected strains were subjected to genomic sequencing using Illumina Nova Seq 6000 next-generation sequencing technology,and their pathogenicity was verified by inoculating mice through the teat canal.The results of virulence gene detection showed that the positive rates of plo,cbpA,nanH,nanP,fimA,fimC-,and fimE genes among the 21 iso-lated strains were 100.0％,38.1％,52.6％,31.6％,61.9％,57.1％,and 52.4％,respectively.In con-trast,the fimG gene was not detected,which was consistent with the results of genomic compari-son by next-generation sequencing.The drug susceptibility test results showed that the susceptibil-ity rates of the isolated strains to clindamycin(CLI),ceftiofur(CEF),and vancomycin(VAN)were 100.0％,while the resistance rates to penicillin(PEN),erythromycin(ERY),sulfamethox-azole-trimethoprim(SXT),florfenicol(FFC),tetracycline(TE),gentamicin(GEN),and enroflox-acin(ENR)were 76.2％,52.1％,52.4％,52.4％,47.6％,42.9％,and 33.3％,respectively.The pro-portion of strains resistant to at least three antimicrobial drugs was 71.4％(15/21).ResFinder a-nalysis of the resistant genes identified 8 types of resistance genes in the genomes of the 9 strains,including ant(2")-Ia and ant(3")-Ia mediating aminoglycoside resistance,cmlA1 and cmx media-ting chloramphenicol resistance,erm(X)and lnu(A)mediating macrolide resistance,sul1 media-ting sulfonamide resistance,and tet(W)mediating tetracycline resistance.Except for tet(W),cm-lA,and erm(X),the other resistance genes were detected for the first time in T.pyogenes in Chi-na.In animal pathogenicity tests,mice inoculated with the isolated strains showed signs of mastitis such as redness,congestion,and inflammatory cell infiltration in the glandular tissue within 24 h,indicating that the isolated strains have pathogenicity to mouse mammary tissue.This study pro-vides preliminary insights into the biological characteristics and pathogenicity of T.pyogenes from caprine mastitis,enriching the data on its drug resistance and genomics,and offering reference and guidance for the prevention and treatment of T.pyogenes infections in large-scale dairy goat farm-ing.

To investigate the distribution and biological characteristics of Trueperella pyogenes in caprine mastitis,67 milk samples from were collected from goats with mastitis in 9 dairy goat farms in the Guanzhong area of Shaanxi Province.A total of 21 strains of T.pyogenes were isolated through bacterial separation and culture.PCR amplification was conducted for 8 virulence genes of the 21 isolated strains,and the susceptibility of the strains to 10 antimicrobial drugs was tested u-sing the micro broth dilution method.Nine selected strains were subjected to genomic sequencing using Illumina Nova Seq 6000 next-generation sequencing technology,and their pathogenicity was verified by inoculating mice through the teat canal.The results of virulence gene detection showed that the positive rates of plo,cbpA,nanH,nanP,fimA,fimC-,and fimE genes among the 21 iso-lated strains were 100.0％,38.1％,52.6％,31.6％,61.9％,57.1％,and 52.4％,respectively.In con-trast,the fimG gene was not detected,which was consistent with the results of genomic compari-son by next-generation sequencing.The drug susceptibility test results showed that the susceptibil-ity rates of the isolated strains to clindamycin(CLI),ceftiofur(CEF),and vancomycin(VAN)were 100.0％,while the resistance rates to penicillin(PEN),erythromycin(ERY),sulfamethox-azole-trimethoprim(SXT),florfenicol(FFC),tetracycline(TE),gentamicin(GEN),and enroflox-acin(ENR)were 76.2％,52.1％,52.4％,52.4％,47.6％,42.9％,and 33.3％,respectively.The pro-portion of strains resistant to at least three antimicrobial drugs was 71.4％(15/21).ResFinder a-nalysis of the resistant genes identified 8 types of resistance genes in the genomes of the 9 strains,including ant(2")-Ia and ant(3")-Ia mediating aminoglycoside resistance,cmlA1 and cmx media-ting chloramphenicol resistance,erm(X)and lnu(A)mediating macrolide resistance,sul1 media-ting sulfonamide resistance,and tet(W)mediating tetracycline resistance.Except for tet(W),cm-lA,and erm(X),the other resistance genes were detected for the first time in T.pyogenes in Chi-na.In animal pathogenicity tests,mice inoculated with the isolated strains showed signs of mastitis such as redness,congestion,and inflammatory cell infiltration in the glandular tissue within 24 h,indicating that the isolated strains have pathogenicity to mouse mammary tissue.This study pro-vides preliminary insights into the biological characteristics and pathogenicity of T.pyogenes from caprine mastitis,enriching the data on its drug resistance and genomics,and offering reference and guidance for the prevention and treatment of T.pyogenes infections in large-scale dairy goat farm-ing.

ObjectiveTo observe the fine structure of the trunk kidney in zebrafish, and to identify its secreted exosomes. MethodsThe microstructure and ultrastructure of the trunk kidney in zebrafish were observed by light microscopy and electron microscopy, and the particle size of exosomes was detected by nanoparticle tracking analysis (NTA). ResultsThe trunk kidney was close and parallel to the spine in adult zebrafish. The nephron consisted of renal tubules and renal corpuscles. The renal tubules could be further divided into three types: proximal convoluted tubules, distal convoluted tubules, and cervical segments. The renal corpuscles were composed of glomerulus and renal capsules. The periodic acid-Schiff (PAS) staining results revealed that there were abundant glycogen granules in the proximal convoluted tubules, with brush-like outline in the apical surface of epithelial cells. Under transmission electron microscopy (TEM), there were exosomes distributed in the lumen of renal tubules, with numerous late endosomes and few number of multivesicular bodies (MVBs) in the cytoplasm of the epithelial cells concentrating on the apical side. Meanwhile, MVBs were also distributed in the apical regions of the renal tubules and the podocytes of the renal glomeruli. Immunohistochemical staining results showed that CD9, CD63 and TSG101 were strongly expressed in the lumen surface of the renal tubules, but weakly expressed in the corpuscles and lumen. NTA and TEM results showed that the exosomes isolated from zebrafish trunk kidney were saucer-like outline, and the particle size mode was 144.4 nm, which was consistent with the characteristics of morphological futures of exosome. ConclusionThe zebrafish somatic kidney has the typical structure of the mammalian kidney and is the urinary organ in the body. The renal tubules have the ability to secrete exosomes, and their formation is a process of releasing poly-vesicles to the free surface of epithelial cells into the extracellular space. This study laid a morphological foundation for further study of exosomes in urinary function in aquatic experimental animals as well as the development and application of related models.

Objective To study the value of using endoscopy iodine staining combined detecting the expression of p53, survivin and telomerase in the diagnosis of early esophageal carcinoma and precancerous lesions. Methods Three hundred patients who received routine gastrescopy and had high risk of esophageal carcinoma were examined by the iodine dyeing on their esophageal mucosa with 2. 5% Lugol solu-tion. Multiple biopsies were taken from the unstained or light-stained areas when their diameters were over 5mm for pathology diagnosis. The expression of p53, survivin and telomerase were detected by immunohistochemical staining. Results With the Lugol staining method, the incidences of light, moderate and high grade dysplasia and early esophageal carcinoma were 16. 3% ,9. 7% ,3.7% and 4. 3% respectively. The expression of p53, survivin and telomerase were related and the unstained were related to the expression of p53, survivin and telomerase in dysplasia and early esophageal carcinoma. Using endoscopy iodine staining combined testing p53, survivin and telomerase showed sensitiv-ity of 100%, specificity of 92. 3% and accuracy of 91.8% to diagnose of early esophageal carcinoma and high grade dysplasia. Conclusion Lugol solution chromoendscopy combined assay of p53, survivin and telomersse might be useful in the diagnosing early esophageal carcino-ma and precancerous lesion.

Objective To investigate the expression and effect of elastin in full-term rats with hyperoxia induced by chronic lung diseases. Methods One hundred and forty-four full-term rats are randomly exposed to hyperoxia (hyperoxia group)and room air(room air group).Chronic lung disease(CLD)is induced by hyperoxia exposure. Gomori's stain for elastic fibers and in situ hybridization methods were used to detect the expressions of secondary crest and tropoelastin mRNA on the 1st,3 rd, 7th, 10th,14th and 21st days after exposure. Results The expressions of secondary crest decreased significantly in hyperoxia group, compared with room air group on the 3rd to 14th days(P＜0.05).The expressions of tropoelastin mRNA decreased significantly in hypemxia group, compared with room air group on the 3rd to 10th days (P＜0.05),otherwise increased significantly from the 14th to 21 st days(P＜0.05). Hyperoxia exposure can delay the peak of tropoelastin mRNA. Conclusion Elastin is involved in the inhibition of alveolarization and lung fibrosis in the development of CLD.