The Salmonella pathogenicity islands (SPIs) play crucial roles in the progression of Salmonella infection.  In this study, we constructed an improved λ Red homologous recombination system to prepare single and triple deletion mutants of 3 prominent SPIs (SPI-1, 2, and 3), aiming at the impact of deletion on morphology, carbon source metabolism, adhesion and invasion capacity, in vivo colonization, and immune efficacy in chicks.  Our examination revealed that the surface of the single deletion mutants (SM6ΔSPI1, ΔSPI2, and ΔSPI3) exhibited a more rugged texture and appeared to be enveloped in a layer of transparent colloid, whereas the morphology of the triple deletion mutant (SM6ΔSPI1&2&3) remained unaltered when compared to the parent strain.  The carbon metabolic spectrum of the SPI mutants underwent profound alterations, with a notable and statistically significant modification observed in 30 out of 95 carbon sources, primarily carbohydrates (17 out of 30).  Furthermore, the adhesion capacity of the 4 mutants to Caco-2 cells was significantly reduced when compared to that of the parent strain.  Moreover, the invasion capacity of mutants SM6ΔSPI1 and SM6ΔSPI1&2&3 exhibited a substantial decrease, while it was enhanced to varying degrees for SM6ΔSPI3 and SM6ΔSPI2.  Importantly, none of the 4 mutants induced any clinical symptoms in the chicks.  However, they did transiently colonize the spleen and liver.  Notably, the SM6ΔSPI1&2&3 mutant was rapidly cleared from both the spleen and liver within 8 days post-infection and no notable pathological changes were observed in the organs.  Additionally, when challenged, the mutants immunized groups displayed a significant increase in antibody levels and alterations in the CD3⁺CD4⁺ and CD3⁺CD8⁺ subpopulations, and the levels of IL-4 and IFN-γ cytokines in the SM6ΔSPI1&2&3 immunized chicken serum surpassed those of other groups.  In summary, the successful construction of the 4 SPI mutants lays the groundwork for further exploration into the pathogenic (including metabolic) mechanisms of SPIs and the development of safe and effective live attenuated Salmonella vaccines or carriers.

Grain-induced subacute ruminal acidosis (SARA) impairs rumen epithelial barrier function, but it is yet to be determined if SARA can cause persistent damage to the morphology and function of the rumen epithelial barrier.  The objective of the present study was to investigate if SARA has persistent effects on the morphological structure and permeability of ruminal epithelium and the expression of the genes involved in epithelial barrier function using a lactating goat model.  Twelve mid-lactating Saanen goats with rumen cannulas were randomly assigned to 1 of 2 groups: control group (Ctrl, n=4) fed a basal diet with a non-fiber carbohydrate (NFC) to neutral detergent fiber (NDF) ratio of 1.40, and SARA group (SARA, n=8) fed the same basal diet but with increasing NFC to NDF ratio from 1.4 to 1.79, 2.31, and 3.23 overtime to induce SARA.  At the end of the SARA challenge (post-SARA), 4 goats were randomly selected from the SARA group and fed only hay mixture ad libitum for another 4 weeks to allow for restitution (post-SARA).  Ruminal pH was continuously recorded to monitor the severity of SARA.  Samples of the ventral ruminal epithelium were collected after slaughter to examine the structural and functional changes of the ruminal epithelium using transmission electron microscopy (TEM), Ussing chambers, qRT-PCR, and Western bolt analyses.  Compared with the Ctrl group, ruminal papilla length, width, surface area and thickness of stratum corneum increased (P<0.05), while stratum spinosum and basale thickness, and total depth of the epithelium decreased (P<0.05) in the SARA group.  These changes diminished or tended to return to the levels of the Ctrl group in the post-SARA group (P>0.05).  The SARA challenge also decreased cellular junction and widened the intercellular space between epithelial cells.  Rumen transepithelial short-circuit current (Isc), tissue conductance (Gt), and mucosa-to-serosa flux of paracellular horseradish peroxidase (HRP) all increased (P<0.05) both in the SARA and post-SARA groups, which indicates that SARA can induce a sustained increase in epithelial permeability and barrier dysfunction.  Moreover, the mRNA and protein expressions of CLDN1, OCLN and ZO-1 were down-regulated (P<0.01) in both the SARA and post-SARA groups.  The results of this study showed that SARA could result in sustained epithelial barrier dysfunction, at both structural and functional levels, which is associated with decreased expression of rumen epithelial tight junction proteins, and the restitution of rumen epithelial barrier function is slower than that of its morphology.

Bulk-SSR method was used to analyze the genetic diversity of 44 open-pollinated varieties collected from Henan, Shandong, Shanxi, and Jilin provinces and Guangxi Zhuang Autonomous Region, China using 70 pairs of SSR primers. The purposes of this study were to (1) compare the genetic diversity among 44 Chinese maize open-pollinated varieties; (2) estimate the minimum number of alleles for construction of a stable dendrogram; and (3) trace the genetic relationships among local germplasm from different regions of China. In total, these 70 SSR primers yielded 292 alleles in 176 samples (4×44) analyzed. The number of alleles per locus was 4.17 on average and ranged from 2 to 8. The highest number of alleles per open-pollinated variety (55.25) was detected in Shanxi germplasm, which indicated that open-pollinated varieties from Shanxi possessed the largest genetic diversity among those from the five locations. The correlation coefficients between different genetic similarity matrices suggested that 200 alleles were sufficient for analysis of the genetic diversity of these 44 open-pollinated varieties. The cluster analysis showed that 44 open-pollinated varieties collected from three growing regions in China were accurately classified into three groups that were highly consistent with their geographic origins, and there is no correlation between GS and geographic distance in this study.

The problem of associating the agricultural market names on web sites with their locations is essential for geographical analysis of the agricultural products. In this paper, an algorithm which employs the administrative ontology and the statistics from the search results were proposed. The experiments with 100 market names collected from web sites were conducted. The experimental results demonstrate that the algorithm proposed obtains satisfactory performance in resolving the problem above, thus the effectiveness of the method is verified.

Classical swine fever caused by Classical swine fever virus (CSFV) is a serious problem for swine industries in developing countries, which successful control of the disease have been relying on vaccination. However, classical swine fever still occurs in some immunized swine herds for various reasons. In this study, we conducted animal experiments to examine the influence of single or mixed infection with Porcine parvo virus (PPV), Pseudorabies virus (PRV) and Porcine reproductive and respiratory syndrome virus (PRRSV) on the protective immunity induced by the Lapinized hog cholera virus (HCLV) vaccine and the pathogenicity of CSFV. In experiment 1, pigs were first inoculated with PPV, PRV or PRRSV, then immunized with HCLV, and finally challenged with a highly virulent CSFV Shimen strain. All of the pigs immunized with HCLV survived after the challenge, while all of the pigs in the non-immunized control group died after the challenge. The pigs in the group immunized with HCLV did not show any clinical symptoms of classical swine fever and were negative with CSFV after the challenge. The pigs infected with the non-CSFV before HCLV immunization did not display any clinical symptoms after the challenge with CSFV Shiman strain, but 11 of the 12 pigs were positive with CSFV. In experiment 2, pre-infections with PPV, PRV, and PRRSV were followed by inoculation with a low-virulence CSFV strain (CSFV 39), and then the pigs were challenged with the CSFV Shimen strain. Infections by either PPV, PRV or PRRSV did not enhance the virulence of CSFV-39, but pigs infected by a mixture of the 3 viruses developed clinical symptoms after inoculation with CSFV-39. The mixed infection also increased mortality caused by the challenge with the CSFV Shimen strain. Together, these results showed PPV, PRV and PRRSV infections in pigs can reduce the efficacy of the HCLV vaccine and enhance the pathogenicity of CSFV, which may partly explain the immunization failure against CSFV in some swine herds.