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Scombrotoxin
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
The role of acid decarboxylases in bacteria is to control the intracellular pH to maintain homoeostasis. Figure 99.3 illustrates the mechanism of histamine formation in an acid response. Histidine is taken up by the bacteria and converted to histamine and CO2, which freely escapes through the cell membrane to the atmosphere. As a result, the reaction eliminates a large quantity of H+ ions from the cell. This mechanism provides resistance to acid stress as a result of a decrease in pH of the surrounding environment, such as during rigor mortis of the fish tissue or fermentation of food products (10,11). Additionally, histamine formation has an important role in the biosynthesis of the siderophore anguibactin of the fish pathogen Vibrio anguillarum (12). Anguibactin is a high-affinity iron chelator secreted by V. anguillarum in iron-limiting conditions, which contributes to the pathogenicity of the bacteria.
Antibacterial Activity of Seaweeds and their Extracts
Published in Leonel Pereira, Therapeutic and Nutritional Uses of Algae, 2018
In a study done by Thirunavukkarasu et al. (2014), the main objective was to isolate bioactive molecules from marine seaweed and check the antimicrobial activity against the fish pathogenic bacteria. Based on the disc diffusion method, Sargassum swartzii (formerly Sargassum wightii) showed a better antimicrobial activity than other seaweed extracts. Chloroform extract showed a minimum zone of inhibition (21.33 mm). The acetone extract of S. swartzii produced a maximum zone of inhibition (26 mm) against Vibrio anguillarum. Methanol extract of S. swartzii showed maximum zone of inhibition (32 mm) against Vibrio parahaemolyticus. Ethyl acetate extract showed maximum zone of inhibition against Vibrio harveyi (24.66 mm). No zone of inhibition was observed in aqueous extract of all the seaweeds against Vibrio sp.
Structural and physiological aspects of cell death
Published in G. F. Wiegertjes, G. Flik, Host-Parasite Interactions, 2004
When enzymatic digestion of the dead cells predominates, colliquative or liquefactive necrosis is the result. This often is seen in context of bacterial or fungal infections in fish, for instance in infections with Vibrio anguillarum (Ransom et al., 1984). These morphological changes are results of processes, which follow cell death and have to be regarded as post-mortem changes, but do not refer to physiological processes which resulted in cell death (for review see Majno and Joris, 1995; Sastry and Rao, 2000). A synthesis about cell physiological and biochemical processes resulting in cell death, however, was achieved only very recently. In this chapter major physiological events that determine the route to and how they lead to cell death are summarized. In addition, implications of cell death for local immune responses are discussed. Structural changes, which follow cell death are well documented in fish under pathogen infection. Biochemical or physiological processes resulting in cell death and its significance for pathological conditions in the context of fish diseases still needs considerable attention.
Quorum sensing pathways in Gram-positive and -negative bacteria: potential of their interruption in abating drug resistance
Published in Journal of Chemotherapy, 2019
Shafiul Haque, Dinesh K. Yadav, Shekhar C. Bisht, Neelam Yadav, Vineeta Singh, Kashyap Kumar Dubey, Arshad Jawed, Mohd Wahid, Sajad Ahmad Dar
Quorum sensing was thought to be confined to a few aquatic organisms earlier but is now extensively accepted for various bacterial species that utilize it as a part of their regulatory machinery.3,4 QS-mediated regulation of virulence determinants have been reported in several Gram-negative pathogens viz. Vibrio anguillarum, Aeromonas salmonicida, Erwinia caratovora, Agrobacterium tumefaciens, Pseudomonas aeruginosa, Burkholderia cepacia and Yersinia pseudotuberculosis.5,6 Control of expression of virulence genes or factors of organisms, parallely to many traits, by QS has a great importance which has led researchers and clinicians to explore the virulence mechanism of bacteria in greater detail at molecular level.
The role of chitosan on oral delivery of peptide-loaded nanoparticle formulation
Published in Journal of Drug Targeting, 2018
Chun Y. Wong, Hani Al-Salami, Crispin R. Dass
Vibrio anguillarum is a common fish pathogen that causes fatal vibriosis in turbot. It is characterised with superficial ulcers, haemorrhagic septicaemia and blood discharge [98]. This pathogen produces endotoxins and caused massive mortalities of turbots, which leaded to severe economic and aquaculture loss. Even though antibiotics and parasiticides are effective in killing the pathogens, these agents have negative impact on antibiotic resistance and environment. Vaccine can prevent fish infection by eliciting the immune response in fish culture. In order to develop an effective oral vaccine against vibriosis, nanoparticles were formed by electrostatic interaction between negatively charged carboxymethylated chitosan and positively charged chitosan [99]. The extracellular antigens of V. anguillarum were loaded in the nanoparticles and administered to turbots orally. It was reported that the nanocarrier could protect antigen from degradation in the stomach, provided controlled-release effects in the intestine and induced both adaptive and innate immune response by enhancing the activity of lysozyme and compliment in fish serum.
Polysaccharide nanoparticles for oral controlled drug delivery: the role of drug–polymer and interpolymer interactions
Published in Expert Opinion on Drug Delivery, 2020
Annalisa Bianchera, Ruggero Bettini
Complex coacervation was described by Vimal and coauthors [43] to encapsulate an expression vector encoding for a gene of Vibrio anguillarum, a common fish pathogen: the vector was mixed with preformed chitosan/TPP nanoparticles at 55°C and vortexed. Almost 80% of the vector was encapsulated by nanoparticles, and efficiently protected from endonuclease degradation: after oral administration to fishes, gene expression could be detected in different organs. Unfortunately, the authors did not report data relevant to the chitosan stability at such temperature [44].