npj Biofilms and Microbiomes
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2020
·Vol. 6
·期 1
·1-12
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IF 7.067
Dong Yuhao,Li Shougang,Zhao Dan,Liu Jin,Ma Shuiyan,Geng Jinzhu,Lu Chengping,Liu Yongjie
Aeromonas hydrophila is the causative agent of motile Aeromonad septicemia in fish. Previous studies have shown that the myo -inositol metabolism is essential for the virulence of this bacterium. IolR is a transcription inhibitor that negatively regulates myo -inositol metabolic activity. While in the process of studying the inositol catabolism in A. hydrophila Chinese epidemic strain NJ-35, we incidentally found that ΔiolR mutant exhibited obvious autoaggregation and increased biofilm formation compared to the wild type. The role of surface proteins in A. hydrophila autoaggregation was confirmed by different degradation treatments. Furthermore, calcium promotes the formation of aggregates, which disappear in the presence of the calcium chelator EGTA. Transcriptome analysis, followed by targeted gene deletion, demonstrated that biofilm formation and autoaggregation caused by the inactivation of iolR was due to the increased transcription of a RTX-family adhesion gene, rmpA . Further, IolR was determined to directly regulate the transcription of rmpA . These results indicated that iolR is negatively involved in autoaggregation and biofilm formation in A. hydrophila , and this involvement was associated with its inhibition on the expression of rmpA .
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高影响因子
FISH & SHELLFISH IMMUNOLOGY
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2019
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IF 3.298
Shengli Fu,Mingmei Ding,Qingjian Liang,Yanjian Yang,Meng Chen,Xiufang Wei,Anli Wang,Shaoan Liao,Jianmin Ye
The immune mechanism elicited in pufferfish ( Takifugu obscurus ) against the invasion of Aeromonas hydrophila is still poorly understood. We examined the spleen of pufferfish at the transcriptome and proteome levels by using Illumina-seq and TMT coupled mass spectrometry after 12 h infection by A. hydrophila , respectively. A total of 2,339 genes (1,512 up-regulated and 827 down-regulated) and 537 (237 up-regulated and 300 down-regulated) proteins were identified. GO and KEGG analyses revealed that the responses to stimulus were the main biological processes , intestinal immune network for IgT production and calcium signaling pathway . Fourteen genes (8 up-regulated and 6 down-regulated) and proteins (5 up-regulated and 9 down-regulated) involved immune responses or signal transduction were validated by qRT-PCR and parallel reaction monitoring to confirm the reliability of the transcriptomic and proteomic analyses, respectively. Moreover, qRT-PCR and flow cytometry were used to detect dynamics of the genes in calcium signaling pathway and changes of concentration of cytoplasm Ca 2+ in spleen cells within a 72 h challenge. This study provides the findings regarding immune response, especially intestinal immune network for IgT production pathway and calcium signaling pathway at the molecular, protein and cellular in pufferfish after infection by A. hydrophila . These results would provide a new insight and molecular targets into the response to pathogenic infection in pufferfish.
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高影响因子
FISH & SHELLFISH IMMUNOLOGY
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2018
·
IF 3.185
Dong-Liang Lu,Samwel Mchele Limbu,Hong-Bo Lv,Qiang Ma,Li-Qiao Chen,Mei-Ling Zhang,Zhen-Yu Du
Dietary α-lipoic acid (LA), β-glucan (Gluc) and l -carnitine (L-Ca) are commonly used additives to promote fish growth and stress resistance in aquaculture production. However their mechanisms and efficiencies in helping fish to resist diseases have not been compared before. In this study, we fed Nile tilapia ( Oreochromis niloticus ) with diets containing appropriate doses of LA, Gluc and L-Ca for five weeks and further intraperitoneally injected the fish with Aeromonas hydrophila . After dietary treatment, none of the additives affected the fish growth, but dietary Gluc and L-Ca reduced protein and lipid body contents in fish, respectively. After A. hydrophila challenge, all fish treated with the three dietary additives showed higher survival rate, but those fed on dietary L-Ca had lower survival than those fed on LA and Gluc diets, indicating high protection efficiency of LA and Gluc. The protective mechanisms of the three feed additives were quite different under A. hydrophila infection. Dietary LA induced higher total antioxidant capacity and higher mRNA expression of anti-oxidative genes than other additives in liver and also activated partly the immune function in serum and spleen. Gluc largely increased the immune function by activating the immunity enzymes in serum, inducing inflammation in liver and increasing the expression of immune genes in spleen and head kidney . Gluc also increased partly the antioxidant capacity in serum and liver and lipid catabolism in liver. L-Ca largely increased lipid catabolism in liver while it increased partly the antioxidant capacities in serum and liver. Taken together, these results indicate that, dietary LA, Gluc and L-Ca have various protective mechanisms and differ in their efficiencies on resisting A. hydrophila infection in Nile tilapia.
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高影响因子
AQUACULTURE
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2025
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IF 3.9
Keda Ying,Xinru Ren,Meiru Tong,Siyu Ye,Yuhong Shi,Qianjin Zhou,Jiong Chen
Multidrug-resistant (MDR) pathogens are a significant threat to aquaculture due to their resistance to most conventional drugs. AcrAB-TolC is a known MDR efflux pump that increases antibiotic resistance. Inhibiting such pumps is a promising strategy in drug discovery. In this study, phytocompounds derived from Commelina communis (Asiatic dayflower) have been identified as candidate inhibitors for AcrB of Aeromonas hydrophila through virtual screening, encompassing molecular docking and molecular dynamics (MD) simulation. Consequently, five phytocompounds from the Asiatic dayflower met the criteria as suggested by the TCMSP database. Among them, flavocommelin, luteolin, and delphin_qt, exhibiting values higher than or equal to the control PAβN, emerged as candidate inhibitors of AcrB protein according to molecular docking analysis. Luteolin, which adhered to Lipinski's rule of five, was stable in binding to AcrB in a 50 ns molecular dynamics simulation. Luteolin also attenuated the reduction in Nile Red fluorescence in a dose-dependent manner, indicating the actual inhibition of the AcrAB-TolC efflux pump of the MDR A. hydrophila Y-1. The checkerboard synergy analysis revealed that luteolin exerted a positive impact on the six tested antibiotics, with fractional inhibitory concentration (FIC) indexes ranging from 0.125 to 0.375. Luteolin and florfenicol were recognized for having the best synergistic activity. When Ctenopharyngodon idella (grass carp) and Plecoglossus altivelis (ayu) were infected by A. hydrophila Y-1, the combination of luteolin and florfenicol markedly enhanced the survival rate and declined the bacterial load, as compared to either luteolin or florfenicol alone. Thus, luteolin is an effective efflux pump inhibitor for AcrAB-TolC of A. hydrophila , enhancing antibiotic sensitivity and exhibiting synergistic effects with antibiotics.
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COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY C-TOXICOLOGY & PHARMACOLOGY
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2020
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IF 2.897
Xianquan Chen,Jiajun Xie,Zhenlu Liu,Peng Yin,Ming Chen,Yongjian Liu,Lixia Tian,Jin Niu
The present study was conducted to evaluate a multi-strain probiotic (MP) on growth performance, immune and antioxidant function, response to hypoxia stress and resistance to Aeromonas hydrophila of grass carp ( Ctenopharyngodon idella ). Based on the viable cell counts of aerobic Bacillus spp., six experimental diets with MP supplemented at 0, 0.34, 1.68, 3.36, 6.72, 10.1 g kg −1 were formulated and 900 juveniles (7.30 ± 0.01 g) were equally distributed into 30 aquaria with respective diet for 60 days. Results showed that fish with 0.34–1.68 g kg −1 MP had better growth and feed utilization. Further, plasma total protein, albumin and high-density lipoprotein were remarkably increased with dietary MP at >1.68 g kg −1 . Dietary MP supplementation at 6.72–10.1 g kg −1 strikingly elevated plasma myeloperoxidase activity and complement C3 content. For fish with MP at 1.68 and 6.72–10.1 g kg −1 , their liver malondialdehyde and glutathione peroxidase were remarkably declined and promoted. After hypoxia stress, fish with 3.36–6.72 g kg −1 MP showed significantly higher respiratory burst activity. Challenge test by A. hydrophila confirmed the protection effects of MP through the decreased cumulative mortality rates. For intestinal histomorphology and enzymatic analyses, fish with 1.68 g kg −1 MP displayed significantly higher intestinal villi height, goblet cells and alkaline phosphatase activity. In conclusion, dietary MP supplementation at 1.68 g kg −1 could promote growth, intestinal morphology and antioxidant capacity , while enhancing host immunity requires higher dosages of MP. Broken-line analysis of weight gain revealed that 1.34 g kg −1 is the optimum dosage for the growth of grass carp.
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高影响因子
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