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Cao JF, Ding LG, Wang QC, Han GK, Qin DC, Cheng GF, Dong ZR, Mu QJ, Kong WG, Liu X, Yu YY, Xu Z. Conserved Role of mTORC1 Signaling in B Cell Immunity in Teleost Fish. THE JOURNAL OF IMMUNOLOGY 2022; 209:1095-1107. [DOI: 10.4049/jimmunol.2200280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 07/19/2022] [Indexed: 01/04/2023]
Abstract
Abstract
Mammalian studies have demonstrated that B cell immune responses are regulated by mechanistic target of rapamycin complex 1 (mTORC1) signaling. Teleost fish represent the oldest living bony vertebrates that contain bona fide B cells. So far, whether the regulatory mechanism of mTORC1 signaling in B cells occurred in teleost fish is still unknown. In this study, we developed a fish model by using rapamycin (RAPA) treatment to inhibit mTORC1 signaling and demonstrated the role of mTORC1 signaling in teleost B cells. In support, we found inhibition of mTORC1 signaling by RAPA decreased the phagocytic capacity, proliferation, and Ig production of B cells. Critically, Flavobacterium columnare induced specific IgM binding in serum, and these titers were significantly inhibited by RAPA treatment, thus decreasing Ab-mediated agglutination of F. columnare and significantly increasing the susceptibility of fish upon F. columnare reinfection. Collectively, our findings elucidated that the mTORC1 pathway is evolutionarily conserved in regulating B cell responses, thus providing a new point for understanding the B cells functions in teleost fish.
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Affiliation(s)
- Jia-feng Cao
- *Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Li-guo Ding
- *Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Qing-chao Wang
- *Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Guang-kun Han
- *Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Da-cheng Qin
- *Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Gao-feng Cheng
- *Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Zhao-ran Dong
- *Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Qing-jiang Mu
- *Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Wei-guang Kong
- *Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Xia Liu
- *Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Yong-yao Yu
- *Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Zhen Xu
- †State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China; and
- ‡Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
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Yang Q, Wang Q, Wu J, Zhang Y, Wei D, Qu B, Liu Y, Fu S. Distinct dynamics of Vibrio parahaemolyticus populations in two farming models. J Appl Microbiol 2021; 133:1146-1155. [PMID: 34260793 DOI: 10.1111/jam.15217] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 06/16/2021] [Accepted: 07/06/2021] [Indexed: 11/28/2022]
Abstract
AIMS Despite the recent prosperity of shrimp cultivation in China, very little is known about how different shrimp farming models influence the dynamics of Vibrio parahaemolyticus populations and the antibiotic resistance of this bacterium. METHODS AND RESULTS To this end, we conducted continuous surveillance of V. parahaemolyticus on four farms over 3 years: two traditional shrimp farms with daily water exchange and two farms operated in the recirculating aquaculture systems (RAS). No antibiotics were used in these farms to exclude the potential impacts of antibiotics on the emergence of antibacterial resistance. Multilocus sequence typing was utilized to characterize the dynamics of V. parahaemolyticus populations. Whole-genome sequencing (WGS) was conducted to determine the representative sequence types (STs) at each farm. Results revealed that the population structure of V. parahaemolyticus remained stable over time in both RAS farms, with only nine and four STs observed at each. In contrast, annual replacement of V. parahaemolyticus populations was observed in traditional farms with 26 and 28 STs identified in rearing water. WGS of 50 isolates divided them into five clusters, of which ST917a isolates harboured a genomic island that disrupted the gene recA. Pair-wised genomic comparison of isolates from the same STs showed that they were genetically related but belonged to different clones associated with geographical distribution. CONCLUSIONS These results suggested that RAS presented a specific ecological niche by minimizing the water exchanges with the external environment. In contrast, traditional farming might pose a food safety issue by introducing new V. parahaemolyticus populations with antibiotic resistance genes. SIGNIFICANCE AND IMPACT OF THE STUDY Our results expose the potential food safety issue associated with conventional agriculture and should encourage the development of preventive strategies to reduce the emergence of resistant V. parahaemolyticus populations.
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Affiliation(s)
- Qian Yang
- Center for Microbial Ecology and Technology (CMET), Ghent University, Ghent, Belgium
| | - Qingyao Wang
- College of Marine Science and Environment, Dalian Ocean University, Dalian, China.,Key Laboratory of Environment Controlled Aquaculture (KLECA), Ministry of Education, Dalian, China
| | - Junmin Wu
- College of Marine Science and Environment, Dalian Ocean University, Dalian, China.,Key Laboratory of Environment Controlled Aquaculture (KLECA), Ministry of Education, Dalian, China
| | - Yixiang Zhang
- CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Shanghai, China
| | - Dawei Wei
- Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Baocheng Qu
- College of Marine Science and Environment, Dalian Ocean University, Dalian, China.,Key Laboratory of Environment Controlled Aquaculture (KLECA), Ministry of Education, Dalian, China
| | - Ying Liu
- College of Marine Science and Environment, Dalian Ocean University, Dalian, China.,Key Laboratory of Environment Controlled Aquaculture (KLECA), Ministry of Education, Dalian, China
| | - Songzhe Fu
- College of Marine Science and Environment, Dalian Ocean University, Dalian, China.,Key Laboratory of Environment Controlled Aquaculture (KLECA), Ministry of Education, Dalian, China
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Growth of Flavobacterium columnare Genomovars in the Presence or Lack of Supplemental Cations. Curr Microbiol 2021; 78:2474-2480. [PMID: 33991203 DOI: 10.1007/s00284-021-02507-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 04/25/2021] [Indexed: 10/21/2022]
Abstract
Flavobacterium columnare is a problematic pathogen for the aquaculture industry where isolates are classified by genomovars. Suspended growth in a low nutrient media, like tryptone yeast extract salts, is a common method used for laboratory study. The presence of calcium and magnesium is the factor contributing to growth, virulence, and biofilm formation for F. columnare. Exponential growth occurs within 24 h for F. columnare when grown in complete tryptone yeast extract salts medium at 30 ºC. Withholding CaCl2 and MgSO4 components from a complete TYES formulation reduced or completely inhibited growth of genomovar I isolates but not the growth of genomovar II, IIB, or III isolates. Only 3 of 20 genomovar I isolates, MS-FC-4, FC-CSF-53, and 023-08-3, could achieve O.D. 540 readings ≥ 0.3 but only after 48-h incubation in cation-restricted TYES. Independently adding CaCl2 or MgSO4 to tryptone and yeast extracts did not result in a genomovar-specific growth phenotype, but generally demonstrated increased clumping with individual isolates presenting abnormal growth. Clumping formed filamentous strings that migrated to the top of the culture tube when isolates were grown in TYE+CaCl2. Several of the F. columnare isolates from all the genomovars exhibited delayed growth when a single cation source was provided. This study demonstrates phenotypic differences between and within genomovars of a single bacterial species when grown under different TYES media conditions.
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Evenhuis JP, Lipscomb R, Birkett C. Virulence variations of Flavobacterium columnare in rainbow trout (Oncorhynchus mykiss) eyed eggs and alevin. JOURNAL OF FISH DISEASES 2021; 44:533-539. [PMID: 33647180 DOI: 10.1111/jfd.13343] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 01/12/2021] [Accepted: 01/13/2021] [Indexed: 06/12/2023]
Abstract
Flavobacterium columnare (Fc) is the causative agent for columnaris disease (CD) in several fish species and an emerging problem for rainbow trout aquaculture. We characterize the virulence phenotype of two Fc isolates, CSF-298-10 and MS-FC-4, against trout from two sources, NCCCWA and a production stock (PS), at the eyed egg and alevin life stages. Immersion challenges demonstrated that NCCCWA eyed eggs were susceptible to the Fc isolate MS-FC-4 (>97% mortality) but no mortality was observed against PS eyed eggs. The CSF-298-10 had little effect on any eyed eggs tested and was not highly virulent to any alevin till day six post-hatch, up to 38% for NCCCWA and ~80% PS alevin. The MS-FC-4 strain produced ≥80% mortality any day an immersion challenge occurred post-hatch. Significant difference in CFU counts was recorded between the Fc strains on 2 days post-hatch immersion challenges. Counts for the NCCCWA alevin were 4.4 × 103 CFU/ml-1 and 1.8 × 106 CFU/ml-1 for the CSF-298-10 strain and MS-FC-4 strain, respectively, and for the PS alevin CSF-298-10 measured 9.9 × 101 CFU/ml-1 and 3.8 × 105 CFU/ml-1 for MS-FC-4. These two Fc isolates present stark differences in virulence phenotypes to both eyed eggs and alevin and present an interesting model system for virulence kinetics and potentially alternative pathogenic pathways.
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Affiliation(s)
- Jason P Evenhuis
- National Center for Cool and Cold Water Aquaculture USDA/ARS, Kearneysville, WV, USA
| | - Ryan Lipscomb
- National Center for Cool and Cold Water Aquaculture USDA/ARS, Kearneysville, WV, USA
| | - Clayton Birkett
- National Center for Cool and Cold Water Aquaculture USDA/ARS, Kearneysville, WV, USA
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