Rhodobacter sphaeroides supplementation improves defense ability of Chinese mitten crab Eriocheir sinensis against Shewanella putrefaciens infection via intestinal flora and metabolism regulation.

Shewanella putrefaciens is a vital bacterial pathogen implicated in serious diseases in Chinese mitten crab Eriocheir sinensis. Yet the use of probiotics to improve the defense ability of E. sinensis against S. putrefaciens infection remains poorly understood. In the present study, the protective effect of dietary R. sphaeroides against S. putrefaciens infection in E. sinensis was evaluated through antioxidant capability, immune response, and survival under bacterial challenge assays, and its protective mechanism was further explored using a combination of intestinal flora and metabolome assays. Our results indicated that dietary R. sphaeroides could significantly improve immunity and antioxidant ability of Chinese mitten crabs, thereby strengthening their disease resistance with the relative percentage survival of 81.09% against S. putrefaciens. In addition, dietary R. sphaeroides could significantly alter the intestinal microbial composition and intestinal metabolism of crabs, causing not only the reduction of potential threatening pathogen load but also the increase of differential metabolites in tryptophan metabolism, pyrimidine metabolism, and glycerophospholipid metabolism. Furthermore, the regulation of differential metabolites such as N-Acetylserotonin positively correlated with beneficial Rhodobacter could be a potential protection strategy for Shewanella infection. To the best of our knowledge, this is the first study to illustrate the protective effect and mechanism of R. sphaeroides supplementation to protect E. sinensis against S. putrefaciens infection.

Shewanella putrefaciens as an emerging pathogen of hepatopancreas necrosis disease in Chinese mitten crab Eriocheir sinensis.

Shewanella putrefaciens has been recognized as an emerging important pathogen in aquaculture. However, scarce information is available on the characterization and microbial control of S. putrefaciens as a causal agent of hepatopancreas necrosis disease in Chinese mitten crab Eriocheir sinensis. In this study, a multi-resistant S. putrefaciens isolate (DZ-A) was identified as a causal pathogen of hepatopancreas necrosis disease in Chinese mitten crabs. It showed a lethal dose (LD50) of 2.20 × 105 CFU ml-1 in Chinese mitten crabs, and multiple resistance to aminoglycoside, chloramphenicol, macrolide, penicillin, peptide, and tetracycline antimicrobials. In addition, Bdellovibrio powder exhibited a significant antibacterial effect against the pathogenic S. putrefaciens, and conferred significant protection to challenged Chinese mitten crabs with relative percentage survivals of 80.00% to 93.33% via significant improvement in their immune response and antioxidant capability. The findings of this study provide valuable insights into the phenotypic characterization and biological control of pathogenic S. putrefaciens in Chinese mitten crabs.

Protective effects of Bacillus licheniformis against Citrobacter freundii infection in Chinese mitten crab Eriocheir sinensis.

Citrobacter freundii is an important bacterial pathogen that causes serious diseases in Chinese mitten crab Eriocheir sinensis. However, scarce information is available on the use of Bacillus licheniformis to protect E. sinensis from C. freundii infection by improving the immunity, antioxidant ability and intestinal flora. In the present study, a 60-day feeding trial was conducted to examine the potential effects of dietary supplementation with antagonistic B. licheniformis on the non-specific immunity, antioxidant capability, intestinal flora and resistance of E. sinensis to C. freundii infection. The results indicated that dietary supplementation of B. licheniformis could boost non-specific immunity and antioxidant capability of E. sinensis in a significant dose-dependent manner respectively by increasing serum lysozyme, superoxide dismutase, alkaline phosphatase, and catalase activities and hepatopancreatic superoxide dismutase, catalase, acid phosphatase activities. In addition, crabs fed diets with B. licheniformis displayed increased composition and diversity of the intestinal flora, and exhibited significant defense against C. freundii infection with the relative percentage survivals ranging from 61.9% to 100.0% for seven days. To our knowledge, this is the first report of antagonistic B. licheniformis as a supplement in Chinese mitten crab feed to effectively resist C. freundii infection by improving the non-specific immunity, antioxidant status and intestinal flora.

[Changes of CCK-8, CGRP, SP, and VIP in the colon and the lung tissue of allergic asthma model rats: an experimental observation].

OBJECTIVE: To observe changes of cholecystokinin octapeptide (CCK-8), calcitonin gene related peptide (CGRP), substance P (SP), and vasoactive intestinal peptide (VIP) in each tissue of the digestive system of allergic asthma (AA) model rats. METHODS: The pulmonary disease (AA) rat model was duplicated by 1% ovalbumin. Its effect on the pathological morphology of the six main parts of the digestive system (stomach, duodenum, jejunum, ileum, colon and rectum) and related regulating factors such as CCK8, CGRP, SP, and VIP were observed. RESULTS: The pathological morphology of the lung was synchronously changed as that of the colon of model rats. But there was no obvious change in the stomach, duodenum, jejunum, ileum, or rectum. Significant changes occurred in CCK8 (79 961.4 +/- 12 577.9, 48 519.5 +/- 12 240.7), CGRP (41 950.1 +/- 12 600.1, 38 059.8 +/- 11 942.4), and SP (88 243.9 +/- 32 177.2, 47 417.8 +/- 16 462.4), and VIP (20 711.4 +/- 7 334.6, 43 208.1 +/- 13 433.8) of the lung tissue and the colon tissue of model rats (P < 0. 05, P < 0.01). But there was no significant change in the aforesaid substances of the stomach, duodenum, jejunum, ileum and rectum (P > 0.05). CONCLUSIONS: Pulmonary disease might affect the colon, inducing pathological changes of the colon tissue and changes of related regulating factors such as CCK8, CGRP, SP, and VIP. It showed no significant effect on the stomach, duodenum, jejunum, ileum and rectum.

Identification of Vibrio ponticus as a bacterial pathogen of coral trout Plectropomus leopardus.

Vibrio ponticus is a vital pathogen with potential danger for aquaculture animals. Yet V. ponticus pathogenic to the coral trout Plectropomus leopardus is still unknown. In this study, a virulent bacterial strain, temporarily named DX2, was isolated from diseased coral trout suffering liver necrosis with cell vacuolar degeneration, and was identified molecularly and phenotypically as V. ponticus. Besides, the DX2 isolate showed an LD50 value of 6.64×105 CFU mL-1, developed multiple resistances to cephalosporins, macrolides, penicillins, peptides, and sulfonamides antimicrobials, and was highly susceptible to doxycycline and florfenicol in aquaculture use. To the best of our knowledge, this is the first report of the pathogenicity of V. ponticus to the coral trout, and the findings provide a reference for the control of pathogenic V. ponticus in the coral trout.

A secure and decentralized SSI authentication protocol with privacy protection and fine-grained access control based on federated blockchain.

Self-sovereign identity authentication protocol is an active research topic in the field of identity authentication and management. However, the current SSI authentication protocols pay little attention to privacy protection and the fine-grained access control. Therefore, a secure and decentralized SSI authentication protocol with privacy protection and fine-grained access control is proposed. Firstly, the formal model of SSI including the SDPP-SSI identity model and management model is presented. And then, based on the federated blockchain, the distributed identifier is used as a global identifier for users in the decentralized domain. Finally, the verifiable statement is encapsulated using a policy control signature supporting privacy protection to develop the user's access control for identity registration in the centralized domain. Compared with the related work (Lin 2018, Zhu 2018, Stokkink 2018, Hammudoglu 2017, Othman 2017, Abraham 2018, Guan 2019, Lin 2019) from controllability, security, flexibility, privacy protection, authentication and fine-grained access control, the proposed SSI authentication protocol not only meets controllability, authentication, and flexibility, but also supports privacy protection and fine-grained access control.