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The effect of TT knockout on c-di-GMP level. The intracellular c-di-GMP content in ZW1 and ZW1∆TT was analyzed with a reporter plasmid. The lower the fluorescence intensity, the lower the c-di-GMP content. Data are presented as means ± SD, n = 3. ** p < 0.01.
Source publication
Edwardsiella piscicida is a pathogenic bacterium, which can infect a number of fish species and cause a disease termed edwardsiellosis, threatening global fish farming with high prevalence and mortality. Thiamine (Vitamin B1), functioning in the form of thiamine pyrophosphate (TPP), is essential for almost all organisms. Bacteria acquire TPP by bio...
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Context 1
... flagella play an important role in motility, the expressions of flhB, flhD, flgA, flgB, fliC1, fliD, and fliF, the first genes of 7 flagellar operons, were analyzed by qRT-PCR. The results showed that the expressions of fliF, flhB, and fliC1 in ZW1∆TT were significantly repressed compared to those in ZW1 or ZW1∆TTc (Figure 2B-D, Supplementary Figure S4). Moreover, the expressions of the other genes in the fliF operon (fliG, fliH, fliI, fliJ, fliK, fliL, fliM, fliN, and fliO), the flhB operon (flhA and flhE), and the fliC operon (fliC2, fliA, and fliZ) were also significantly reduced in ZW1∆TT ( Figure 2B-D). ...
Context 2
... effect of TT knockout on the intracellular level of c-di-GMP was examined with a c-di-GMP sensing reporter plasmid [35]. Compared to ZW1, ZW1∆TT displayed a significantly more intense fluorescence signal, indicating a lower amount of c-di-GMP in ZW1∆TT (Figure 4). To assess the importance of c-di-GMP to the virulence associated traits of ZW1, the strain ZW1∆TT-adrA was constructed, which is ZW1∆TT overexpressing adrA, a DGC gene with certified function in c-di-GMP synthesis [36]. ...
Citations
... 子/系统被鉴定, 其效应因子及其作用也逐渐被解 析 [12,13] , 一些新型毒力因子如血清诱导蛋白Sip1和 S i p 2 [ 1 4 , 1 5 ] 、 毒 素 抗 毒 素 系 统 Ye f M -Yo e B 和 H i g -BA [16,17] 、硫氧还蛋白样蛋白TrxH/Trxlp [18,19] 、丝氨酸 渗透酶YhaO [20] 、硫胺素转运蛋白TT [21] 、酸己糖转运 系统调节蛋白UhpA [22] 、血红素利用蛋白HutZ [ . 在杀鱼爱德华氏菌中, 已发现质膜双组 分系统CpxRA [27] 、内膜蛋白YccA [28] 、周质蛋白酶 DegP [29] 和质膜蛋白酶FtsH [30] 等与细菌抗逆与毒力密 切相关. ...
... (Shanghai, China). Then a polygene phylogenetic tree was constructed using the maximum likelihood (ML) method in MEGA 7.0 [25] software with bootstrap values based on 1000 replications. F. delphinoides CBS 110140 was used as an outgroup. ...
Sorghum bicolor is cultivated worldwide. Leaf spot of sorghum, which leads to leaf lesions and yield reduction, is a prevalent and serious disease in Guizhou Province, southwest China. In August 2021, new leaf spot symptoms were observed on sorghum leaves. In this study, traditional methods and modern molecular biology techniques were used to isolate and identify the pathogen. Sorghum inoculated with the isolate GY1021 resulted in reddish brown lesion that similar to symptoms observed in the field: the original isolate inoculated was reisolated and Koch’s postulates were fulfilled. Based on morphological features and phylogenetic analysis of the internal transcribed spacer (ITS) combined sequence with β-tubulin (TUB2) and translation elongation factor 1-α (TEF-1α) genes, the isolate was identified as Fusarium thapsinum (Strain accession: GY 1021; GenBank Accession: ITS (ON882046), TEF-1α (OP096445), and β-TUB (OP096446)). Then, we studied the bioactivity of various natural products and microorganisms against F. thapsinum using the dual culture experiment. Carvacrol, 2-allylphenol, honokiol, and cinnamaldehyde showed excellent antifungal activity, with EC50 values of 24.19, 7.18, 46.18, and 52.81 µg/mL, respectively. The bioactivity of six antagonistic bacteria was measured using a dual culture experiment and the mycelial growth rate method. Paenibacillus polymyxa, Bacillus amyloliquefaciens and Bacillus velezensis displayed significant antifungal effects against F. thapsinum. This study provides a theoretical basis for the green control of leaf spot of sorghum.
... Bacteria synthesize the TPP or acquire it via the transportation of exogenous thiamine [37]. Deletion of the thiamine transporter (TT) operon in Edwardsiella piscicida, the causative agent of the edwardsiellosis disease in fish, resulted in attenuated pathogenicity, reduced host cell adhesion, and impaired abilities associated with motility [38]. ...
... Bacteria synthesize the TPP or acquire it via the transportation of exogenous thiamine [37]. Deletion of the thiamine transporter (TT) operon in Edwardsiella piscicida, the causative agent of the edwardsiellosis disease in fish, resulted in attenuated pathogenicity, reduced host cell adhesion, and impaired abilities associated with motility [38]. ...
Flavobacterium psychrophilum (Fp), the causative agent of Bacterial Cold-Water disease in salmonids, causes substantial losses in aquaculture. Bacterial outer membrane vesicles (OMVs) contain several virulence factors, enzymes, toxins, and nucleic acids and are expected to play an essential role in host–pathogen interactions. In this study, we used transcriptome sequencing, RNA-seq, to investigate the expression abundance of the protein-coding genes in the Fp OMVs versus the Fp whole cell. RNA-seq identified 2190 transcripts expressed in the whole cell and 2046 transcripts in OMVs. Of them, 168 transcripts were uniquely identified in OMVs, 312 transcripts were expressed only in the whole cell, and 1878 transcripts were shared in the two sets. Functional annotation analysis of the OMV-abundant transcripts showed an association with the bacterial translation machinery and histone-like DNA-binding proteins. RNA-Seq of the pathogen transcriptome on day 5 post-infection of Fp-resistant versus Fp-susceptible rainbow trout genetic lines revealed differential gene expression of OMV-enriched genes, suggesting a role for the OMVs in shaping the host–microbe interaction. Interestingly, a cell wall-associated hydrolase (CWH) gene was the most highly expressed gene in OMVs and among the top upregulated transcripts in susceptible fish. The CWH sequence was conserved in 51 different strains of Fp. The study provides insights into the potential role of OMVs in host–pathogen interactions and explores microbial genes essential for virulence and pathogenesis.
... Strain accession and GenBank accession were derived from NCBI's GenBank nucleotide database (http://www.ncbi.nlm.nih.gov (accessed on 19 June 2022)), and a polygene phylogenetic tree was constructed using the maximum likelihood (ML) method in MEGA 7.0 software [21] with bootstrap values based on 1000 replications. Monilochaetes infuscans (CBS 896.96) was used as an outgroup. ...
Sorghum bicolor is cultivated worldwide. Leaf spots on sorghum, which lead to leaf lesions and impaired growth, are prevalent and severe in Guizhou Province, Southwest China. In August 2021, new leaf spot symptoms were observed on sorghum plants growing in agricultural fields. We used conventional tissue isolation methods and pathogenicity determination tests. Inoculations of sorghum with isolate 022ZW resulted in brown lesions similar to those observed under field conditions. The original inoculated isolates were reisolated and fulfilled Koch’s postulates. Based on the morphological character and phylogenetic analyses of the combined sequences of the internal transcribed spacer (ITS) region and the β-tubulin (TUB2) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes, we identified the isolated fungus as C. fructicola. This paper is the first to report this fungus-causing disease in sorghum leaves. We studied the sensitivity of the pathogen to various phytochemicals. The sensitivity of C. fructicola to seven phytochemicals was measured using the mycelial growth rate method. Honokiol, magnolol, thymol, and carvacrol displayed good antifungal effects, with EC50 (concentration for 50% of the maximal effect) values of 21.70 ± 0.81, 24.19 ± 0.49, 31.97 ± 0.51, and 31.04 ± 0.891 µg/mL, respectively. We tested the control effect of the seven phytochemicals on the anthracnose caused by C. fructicola: honokiol and magnolol displayed good field efficacy. In this study, we expand the host range of C. fructicola, providing a basis for controlling sorghum leaf diseases caused by C. fructicola.
Translucent post-larvae disease (TPD), caused by Vibrio parahaemolyticus (Vp TPD), has become an emerging shrimp disease, affecting more than 70%–80% of coastal shrimp nurseries in China in spring 2020. Here, we investigated the key virulence factors of Vp TPD by analyzing protein fragments, related genomic information, as well as experimental challenge tests. After investigating the toxic effects of purified protein fragments with different molecular weights (MWs) from Vp TPD, we found that only the protein fragments with MW >100 kDa showed similar lethality to live Vp TPD in the experimental challenge test using post-larvae shrimp. Meanwhile, similar histopathological changes exhibiting in the hepatopancreas and midgut of the diseased individuals were observed in the post-larvae shrimp challenged with either bacterial protein fragments (MW >100 kDa) or live Vp TPD. Based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry analyses, two novel proteins, Vibrio high virulent protein (VHVP)-1 and VHVP-2, were identified as the candidates of key virulence factors to cause TPD. Moreover, VHVP-1 and VHVP-2 were found to be encoded by two genes (vhvp-1 and vhvp-2) tandemly located on a 187,791-bp plasmid and were predicted to depend on the same promoter following a comparative genomic analysis. Further epidemiological investigation and challenge test indicated that the V. parahaemolyticus isolate carrying only the vhvp-1 gene and lacking vhvp-2 gene could not cause mortality of experimental Penaeus vannamei post-larvae. The mutant (Δvhvp-2) by deleting vhvp-2 gene could only cause 4.92% of accumulative mortality of post-larvae that is similar to the non-Vp TPD Vibrio strain. Additionally, the complemented strains, Δvhvp-2/pBT3-vhvp-2 and Δvhvp-2/pwtCas9-vhvp-2, showed similar virulence to the wild-type Vp TPD. The results demonstrated that V. parahaemolyticus becomes lethal to post-larval shrimp by acquiring the VHVP-2 virulence factor. This study sheds light on further investigations of the pathogenic mechanism of Vp TPD and the development of strategies for early diagnosis of TPD in shrimp hatcheries.
IMPORTANCE
As a severe emerging shrimp disease, TPD has heavily impacted the shrimp aquaculture industry and resulted in serious economic losses in China since spring 2020. This study aimed to identify the key virulent factors and related genes of the Vp TPD, for a better understanding of its pathogenicity of the novel highly lethal infectious pathogen, as well as its molecular epidemiological characteristics in China. The present study revealed that a novel protein, Vibrio high virulent protein-2 (MW >100 kDa), is responsible to the lethal virulence of V. parahaemolyticus to shrimp post-larvae. The results are essential for effectively diagnosing and monitoring novel pathogenic bacteria, like Vp TPD, in aquaculture shrimps and would be beneficial to the fisheries department in early warning of Vp TPD emergence and developing prevention strategies to reduce economic losses due to severe outbreaks of TPD. Elucidation of the key virulence genes and genomics of Vp TPD could also provide valuable information on the evolution and ecology of this emerging pathogen in aquaculture environments.
Cathepsin H and Cathepsin B are two lysosomal cysteine proteases participating in various physiological processes including immune responses. In fish, the functional roles of Cathepsin H and Cathepsin B during bacterial infection are less understood. In a previous work, we characterized a Cathepsin B homologue (CsCatB) of half-smooth tongue sole (Cynoglossus semilaevis), an economically valuable fish species in China. In this report, we identified a Cathepsin H homologue (CsCatH) from C. semilaevis. In healthy tongue sole, the transcriptional expression of CsCatH was detected in nine different tissues. Laser scanning confocal microscopic analysis showed that ectopically expressed CsCatH and CsCatB were co-localized with the lysosome. Upon infection by Edwardsiella tarda, a significant fish pathogen which caused a severe fish disease termed edwardsiellosis, the expressions of CsCatH and CsCatB were remarkedly upregulated. The knockdown of CsCatH and CsCatB significantly increased the replication of E. tarda and mitigated E. tarda-induced apoptosis in tongue sole tissues. These findings revealed the importance of CsCatH and CsCatB in anti-bacterial immunity of tongue sole.
