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1.
Lysozyme acts as a non‐specific defence substance and is found in the peripheral blood, cutaneous mucus and certain tissues of marine and freshwater fishes. In the present study, we examined the effect of various environmental factors (water temperature, salinity, pH and suspended sediments) on plasma lysozyme activity in the Nile tilapia, Oreochromis niloticus L. When the fish were reared at different water temperatures (18.4, 23, 28 and 33°C), plasma lysozyme activity increased at 28°C after 2 and 4 weeks. A significant decrease in lysozyme activity was found in the fish reared at 33°C for 4 weeks. These results suggest that there is a water temperature range that affects the amount of plasma lysozyme activity that can be detected. Fish cultured at 24 g L?1 of salinity for 2 and 4 weeks and 12 g L?1 for 4 weeks resulted in significantly increased plasma lysozyme activity, suggesting that environmental salinity also affects the amount of plasma lysozyme that can be detected. Lysozyme activity also significantly increased when the fish were held in acidic water at pH 4.0 and in suspended sediments at 2000 mg L?1 for 2 weeks. It was concluded that changes in some aquatic environmental factors affect the non‐specific immune responses of Nile tilapia.  相似文献   

2.
分别在拥挤胁迫后第3、10、20、30天对鲫鱼(Carassiusauratus)血液皮质醇水平和血液溶菌酶水平进行了检测,并在每次采集血样后用嗜水气单胞菌(Aeromonashydrophila)进行人工感染以评估鱼体抵抗力。结果显示,血液皮质醇水平在胁迫后几天内显著升高(P<0.005),随后虽有所下降,但至第30天高密度组仍保持较高水平(216.32±11.91)ng/mL。实验初期,血液溶菌酶水平小幅升高,但经过长时间的拥挤后,高密度组血液溶菌酶活性受到极大抑制,显著低于同期对照组(P<0.01)。攻毒后的死亡率与胁迫时间成正相关,在最后一次采样期,高密度组死亡率高达58.3%,而同期对照组仅为16.7%,两者具统计学差异(P<0.01)。实验表明,经过拥挤胁迫后,鲫鱼血液皮质醇水平和溶菌酶水平均发生了变化,短期内,两者成正相关,而长期胁迫则表现为负相关。另外,拥挤胁迫也引起了鱼体抵抗力的下降。  相似文献   

3.
The innate immune system of fish is considered first line of defense against a broad spectrum of pathogens. Being a component of innate immunity and lying at the interface between fish and the aqueous environment, skin mucus plays a frontier role in protecting fish from infections. In the present study, skin mucus of Cirrhinus mrigala, Labeo rohita, Catla catla, Rita rita and Channa punctata, inhabiting different ecological niches, was analyzed to characterize potential innate immune factors such as lysozyme, proteases, phosphatases, esterase and sialic acid. The enzyme activities were high in bottom dweller species, C. punctata and C. mrigala, and low in clean water inhabiting species, L. rohita and C. catla. An inverse relationship was observed between the level of enzyme activity and the sialic acid content in these fish species. In R. rita, however, the levels of all factors were found to be low. Zymographic analysis with labeled Micrococcus lysodeikticus revealed three isoforms of lysozyme in C. punctata and two in each species, C. mrigala, L. rohita and C. catla. In R. rita, lysozyme could not be detected. Gelatin zymography revealed that serine and metalloproteases were the major mucus proteases in all fish species investigated. In addition, trypsin-like protease and Ca(++)-specific serine proteases were observed in skin mucus. Increased knowledge of these parameters could be useful in understanding the role of skin mucus in the innate immune system of fish species inhabiting different ecological niches.  相似文献   

4.
A prebiotic is a non‐digestible food ingredient that beneficially affects the host by selectively stimulating the growth and/or the activity of one or a limited number of bacteria in the colon. Despite the potential benefits to health and performance as noted in various terrestrial animals, the use of prebiotics in the farming of fish and shellfish has been less investigated. The studies of prebiotics in fish and shellfish have investigated the following parameters: effect on growth, feed conversion, gut microbiota, cell damage/morphology, resistance against pathogenic bacteria and innate immune parameters such as alternative complement activity (ACH50), lysozyme activity, natural haemagglutination activity, respiratory burst, superoxide dismutase activity and phagocytic activity. This review discusses the results from these studies and the methods used. If the use of prebiotics leads to health responses becoming more clearly manifested in fish and shellfish, then prebiotics might have the potential to increase the efficiency and sustainability of aquaculture production. However, large gaps of knowledge exist. To fully conclude on the effects of adding prebiotics in fish diets, more research efforts are needed to provide the aquaculture industry, the scientific community, the regulatory bodies and the general public with the necessary information and tools.  相似文献   

5.
Lysozymes play vital roles in humoural immune response against bacterial invasion by its lytic activity. In the present study, a new C‐type lysozyme was identified and characterized from Chinese soft‐shelled turtle Pelodiscus sinensis. The full‐length cDNA of PslysC was of 923 bp, encoding a polypeptide of 148 amino acid residues. The multiple alignments and phylogenetic relationship analysis revealed the highly enzyme‐related conserved residues. The real‐time PCR analysis suggested that PslysC was constitutively expressed in a wide range of tissues with highest level in blood cells and liver. The expression of PslysC could be significantly up‐regulated under Aeromonas jandaei infection and ammonia exposure, while no significant changes were found under Poly I:C infection. The rPslysC protein was expressed in E. coli and purified by Ni‐NTA. The optimal pH and temperature for rPslysC protein lytic activities were determined at pH 7 and 30℃. rPslysC can inhibit the growth of eight kinds of Gram‐negative bacteria, and three kinds of Gram‐positive bacteria. The binding activity of rPslysC to different microbial polysaccharides and microorganism was analysed. The results showed that rPslysC could bind to selected bacteria, and exhibit a strong binding activity to lipopolysaccharide and peptidoglycan, but a weak binding activity to β‐glucan. This suggests that the binding activity might be the major mechanism of action to realize the antibacterial activity. The present study will provide helpful evidence to further understand the innate immunity of P. sinensis, and the interaction mechanisms of C‐type lysozymes with bacterial membranes.  相似文献   

6.
Lysozyme was purified from the ovary of tilapia, Oreochromis mossambicus, with two steps, chitin coated-cellulose and Sephadex G-100, and its biological properties were investigated. Purified lysozyme had a molecular mass of 15kDa on SDS-PAGE under reducing condition. Analyses with antibody (a-EL) against the purified lysozyme revealed that serum and egg extract reacted with a-EL and the precipitin lines fused completely. The enzyme activities in serum and egg extract were inhibited by adding serially diluted a-EL. Therefore, egg extract and serum lysozyme was immunologically identical. Immunohistochemically, lysozyme was observed in the ooplasm of the oocytes laden with yolk but not in the follicle layers, egg envelope or immature oocytes (the peri-nucleolus stage). In addition, the enzyme activity in the large oocytes was higher than that in the small ones. These results suggest that lysozyme detected in the oocytes is derived from extra-ovarian tissue and transfers from the maternal circulation. Lysozyme activity in the serum of female tilapia increased with oocyte development, suggesting that the change in the enzyme level may be partially related to the reproductive events (especially vitellogenesis) of the female fish.  相似文献   

7.
In this study, the effect of extracts of two herbs (Oliviera decumbens and Satureja khuzestanica) on immune response of carp was investigated. At the beginning of experiment, fish were divided to two groups including vaccinated (using vaccine developed against A. hydrophila) and non‐vaccinated. Fish in both groups were fed diets containing O. decumbens and S. khuzestanica and combination of two herbal extracts for 5 weeks. Control fish (negative control) and fish vaccinated only (positive control) were fed basal diets without supplements of herbal extracts. Lysozyme activity, antibody titre, complement activity and bactericidal activity in serum were measured. After 5 weeks feeding, fish were infected with A. hydrophila and mortalities were recorded. In both experimental groups, no significant differences were found in terms of alternative haemolytic complement (ACH50) activity and antibody titres of Serum. In non‐vaccinated fish group, lysozyme and bactericidal activity of fish fed S. khuzestanica or combination of O. decumbens and S. khuzestanica was higher compared with control and other experimental treatments. In vaccinated fish group, the lysozyme and bactericidal activity was not significant in all treatments compared with control group. The results of this study showed that feeding non‐vaccinated and vaccinated carp with only S. khuzestanica or in combination with O. decumbens enhance only some immunity indices including lysozyme and bactericidal activity in non‐vaccinated fish and these extracts have no immunological stimulatory role on vaccinated individuals.  相似文献   

8.
The present work has been undertaken to analyse the antibacterial activity and innate immune components in the skin mucus of Indian major carp, Cirrhinus mrigala. Skin mucus was extracted separately in triple‐distilled water (TDW), 3% acetic acid (3% AA) or 0.1% trifluoroacetic acid (1% TFA). All mucus extracts exhibited different spectrum of the antibacterial activity against different groups of pathogenic bacteria. Protein profiling by polyacrylamide gel electrophoresis revealed a series of protein bands in the TDW extract, four major protein bands in the AA extract and two protein bands in the TFA extract. Tandem mass spectrometry analysis of distinct protein bands identified potential innate immune factors – histone H2A, histone H3, histone H4, haemoglobin, cofilin and nucleoside diphosphate kinase in the TDW extract, and ubiquitin and histone H2B isoforms in acidic extracts of skin mucus of C. mrigala. The presence of these innate immune molecules suggests that skin mucus play an important role in the protection of the fish against microbial invasion.  相似文献   

9.
This study was conducted to evaluate the effect of dietary lysozyme supplementation on growth performance and plasma biochemical parameters of rainbow trout (Oncorhynchus mykiss). Graded levels of lysozyme [0 (control), 150, 300, 450 and 600 mg kg?1 diet] were fed to fish (initial average weight 7.76 g) for 10 weeks. Dietary lysozyme supplementation regardless of inclusion level generally improved the growth, feed utilization and nutrient retention, but significant differences were mainly observed between the 450 or 600 mg kg?1 lysozyme group and the control group. Lysozyme supplementation generally decreased the plasma aspartate aminotransferase and alanine aminotransferase (ALT) activities, but significant difference was only observed in the ALT activity between the 450 mg kg?1 lysozyme group and the control group. In contrast, lysozyme supplementation generally increased the plasma alkaline phosphatase and lysozyme activities, but significant difference was only observed in the lysozyme activity between the 600 mg kg?1 lysozyme group and the control group. Lysozyme supplementation generally increased the plasma antioxidant activities of enzymes (including superoxide dismutase, glutathione peroxidase and catalase) and total antioxidant capacity, but decreased the plasma malondialdehyde level. These results suggest that dietary 450–600 mg kg?1 lysozyme inclusion may improve the growth and non‐specific immune response of rainbow trout.  相似文献   

10.
In response to pathogens, the higher vertebrate innate immune system activates pro‐inflammatory caspase‐1 which is responsible for the processing and secretion of several important cytokines involved in the host's defence against infection. To date, caspase‐1 has been described in few teleost fish, and its activity has been demonstrated through substrate cleavage and inhibition by pharmacological agents. In this study, the detection of the active form of caspase‐1 during the immune response in salmonid fish is described, where two antibodies were produced. These antibodies differentially recognize the structural epitopes of the inactive pro‐caspase‐1 and the processed active form of the caspase. Firstly, caspase‐1 activation was demonstrated in vitro by ELISA, Western blotting and immunocytochemistry in rainbow trout macrophages exposed to different pathogen‐associated molecular patterns plus the pathogen Aeromonas hydrophila. This activity was clearly abrogated by a caspase inhibitor and seems to be unrelated to IL‐1β secretion. Caspase‐1 activation was then validated in vivo in gill cells from fish challenged with Aeromonas salmonicida. These results represent the first demonstration of caspase‐1 activation in salmonids, and the first evidence of the putative regulatory role which this protease plays in inflammatory response in this fish group, as described for some other teleosts and mammals.  相似文献   

11.
We investigated the effects of hydrogen peroxide on mucous cells and lysozymes in gill tissue of olive flounder. Morphological analysis revealed significant changes in the number of mucous cells after exposure to 300 and 500 mg L ? 1 hydrogen peroxide; however, there was no detectable difference in the 100 mg L ? 1 group. Lysozyme activities declined gradually in the gill mucus, but in contrast activities in serum increased significantly following the completion of treatment. The hepatic c‐ and g‐type lysozyme levels showed significant responses, indicating that the liver is a major lysozyme producer in response to stress condition; however, in the head kidney, there were no significant changes in the g‐type lysozyme level in all the groups, while the only detectable difference with the c‐type gene in the 300 mg L ? 1. While the treatments showed no significant changes compared with the control for either branchial lysozyme, there were significant differences in c‐type lysozyme between the 3rd treatment and 5 day. Taken together, our data indicate that hydrogen peroxide treatment may lead to modulation of the innate immune response of olive flounder; therefore, the application of hydrogen peroxide in a field system will require more attention to dose and timing effects.  相似文献   

12.
Two consecutive studies were conducted to evaluate the dietary supplementation of citrus by‐products (CB) fermented with probiotic bacteria on growth performance, feed utilization, innate immune responses and disease resistance of juvenile olive flounder. In Experiment I, five diets were formulated to contain 0% (control) or 3% four different CB fermented with Bacillus subtilis (BS), Enterococcus faecium (EF), Lactobacillus rhamnosus (LR) and L. plantarum (LP) (designated as CON, CBF‐BS, CBF‐EF, CBF‐LR and CBF‐LP, respectively). During 10 weeks of a feeding trial, growth performance and feed efficiency were not significantly different among all the fish groups. However, fish fed CBF containing diets had significantly higher survivals than the CON group. Disease resistance of fish against Edwardsiella tarda was increased by the fermentation of CB. In Experiment II, we chose the BS as a promising probiotic and formulated five diets to contain 0%, 2%, 4%, 6% and 8% CBF‐BS. Growth performance was not significantly affected by the CBF‐BS supplementation during 6 weeks of a feeding trial. Innate immunity of fish was significantly enhanced by CBF‐BS supplementation. Myeloperoxidase and lysozyme activities were increased in a dose‐dependent manner by dietary CBF‐BS inclusions. In a consecutive challenge test against E. tarda, an increased disease resistance was found by CBF‐BS supplementation. These studies indicate that the fermentation process of CB with probiotic has beneficial effects on innate immunity and thereby increases disease resistance of olive flounder against E. tarda. Bacillus subtilis can be used as a promising probiotic microbe for by‐product fermentation in fish feeds.  相似文献   

13.
The immune responses of mucus from the skin of turbot, Scophthalmus maximus, were studied in relation to changing water temperature. Groups of fish were exposed to a programmed increase of 3 °C per 48 h, until the experimental water temperatures of 16, 20, 23, 25, 27 or 28 °C were reached. After 48 h at the relevant temperature, the expressions of immune‐related factors were determined, including immunoglobulin M (IgM), IL‐1β, hepcidin, transferrin, lysozyme, acid/alkaline phosphatase and superoxide dismutase using RT–PCR and spectrophotometric methods. Significant changes in mucus immunity were observed, which paralleled with those previously reported for serum in other fish species. Hence, it is suggested that the serum and mucus immune system of turbot have a similar regulatory system. This information could be useful in better understanding the role of the mucus as a component of the innate immune system.  相似文献   

14.
Argulus siamensis is a major pathogen in freshwater aquaculture. The immune responses of Indian major carp, Labeo rohita to experimental infection of A. siamensis was evaluated by quantitation of immune‐relevant gene expression in head kidney and skin, and serum innate immune parameters through the course of infection. In skin of infected fish, antioxidant genes like natural killer cell enhancing factor (NKEF‐B) and superoxide dismutase (MnSOD) were significantly up‐regulated in addition to lysozyme G and β2 microglobulin (β2M). Both tumour necrosis factor α (TNFα) and toll‐like receptor 22 (TLR22) genes were significantly down‐regulated in skin during early phases of the infection. Most of the genes exhibited significant down‐regulation in head kidney; immunoglobulin (IgM) and β2M genes being the exceptions which were significantly up‐regulated at 12 h and 3 days post infection. Most of the innate immune parameters like serum complement activity and ceruloplasmin levels showed significant reduction in infected fish. The observed results are indicative of A. siamensis modulating the immune response of rohu by down‐regulation of many immune factors which may explain the susceptibility of rohu to A. siamensis infection. The interaction of this parasite with the host need to be further explored to understand its pathogenesis.  相似文献   

15.
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16.
This study tested the onion powder (OP) supplementation in the diet of the olive flounder on the growth, body composition, and lysozyme activity. Thirty‐five fish averaging 5.1 g were randomly stocked into 18 individual 180‐L flow‐through tanks. A commercially available OP was used as a dietary additive. Six experimental diets were prepared to contain OP at the concentrations of 0, 0.5, 1, 2, 3, and 5% for diets OP‐0, OP‐0.5, OP‐1, OP‐2, OP‐3, and OP‐5, respectively. After the 8‐wk feeding trial, 20 fish from each tank were infected with Edwardsiella tarda and mortality was monitored for the following 96 h. No distinctive improvement in survival, weight gain, or feed efficiency of fish was observed at the end of the 8‐wk feeding trial. Lysozyme activity in fish fed the OP‐0.5 diet was higher than that of fish fed the OP‐0, OP‐1, OP‐2, OP‐3, and OP‐5 diets. The cumulative mortality of fish fed the OP‐0.5, OP‐1, OP‐2, OP‐3, and OP‐5 diets was lower than that of fish fed the OP‐0 diet at 72 h after E. tarda infection. Dietary inclusion of 0.5% OP was effective at improving lysozyme activity of fish, and OP seemed to be an effective immunostimulant to lower mortality upon E. tarda infection.  相似文献   

17.
The in vitro and in vivo effect of prolactin (PRL) on kidney macrophages from Atlantic salmon (Salmo salar) was investigated under the assumption that PRL stimulates immune innate response in mammals. Kidney macrophages were treated two ways: first, cultured in RPMI 1640 medium containing 10, 25, 50 and 100 ng/mL of PRL and second, isolated from a fish with a PRL-injected dose of 100 ng/Kg. Reduced nitro blue tetrazolium (formazan) was used to produce intracellular superoxide anion. Phagocytic activity of PRL was determined in treated cells by optical microscopy observation of phagocytized Congo red-stained yeast. Kidney lysozyme activity was measured in PRL-injected fish. In vitro and in vivo macrophages treated with PRL presented an enhanced superoxide anion production, elevated phagocytic index and increased phagocytic activity. Treated fish showed higher levels of lysozyme activity in the head kidney compared to the control. These results indicate that PRL-stimulated innate immune response in Atlantic salmon and future studies will allow us to assess the possibility of using PRL as an immunostimulant in the Chilean salmon industry.  相似文献   

18.
崔俊霞  徐田军 《水产学报》2023,47(5):059402-059402
先天免疫是宿主识别病原及消除病原感染的第一道防线。模式识别受体是参与识别病原入侵的主要分子，主要包括Toll样受体、RIG-I样受体、NOD样受体和C型凝集素受体等。模式识别受体在识别病原相关分子模式后，激活机体的先天免疫信号通路，诱导炎症细胞因子和干扰素的产生，从而启动抵抗病原入侵的免疫应答。越来越多的证据表明，免疫应答的激活、维持和终止受到了严格的调节，使机体在保持一定免疫强度的同时避免产生过度的免疫反应。microRNA是一类长度为18～23 nt的微小非编码RNA，是鱼类先天免疫应答网络中的重要调控因子。近年来，microRNA在鱼类免疫学领域已开展了大量的研究，但缺乏对其进行及时地全面性的总结。本文综述了近年来miRNA在鱼类先天免疫反应中的研究进展，以期为鱼类的分子抗病育种及疾病防控研究提供一些思路。  相似文献   

19.
The study was undertaken to determine the modulation in innate immune response of rohu (Labeo rohita) during experimental freshwater lice Argulus siamensis infection. Results showed that serum α‐2 macroglobulin (α‐2M) activity, ceruloplasmin level and alternative complement activity were significantly (P<0.05) lower in fish at different degrees of lice infection in comparison with uninfected control. No significant difference (P>0.05) in haemagglutination titre was observed in fish with low‐ and high‐degree lice infections as compared with uninfected control. The serum lysozyme level was significantly (P<0.05) lower in low degree of lice infection as compared with control fish. The total serum antiprotease, myeloperoxidase activity and total protein level were not significantly different (P>0.05) in different degrees of lice‐infected fish with respect to the control fish. The study indicated that A. siamensis infection modulated the immune system of rohu by suppressing the α‐2M, serum complement activities and ceruloplasmin level and through induction of stress response. The baseline data obtained in the present study have tremendous importance in understanding the susceptibility of rohu to different degrees of parasitosis and might be useful in controlling this dreaded ectoparasitic infection in fish.  相似文献   

20.
The antioxidant defence and immune response of rainbow trout (Oncorhynchus mykiss) that had received plant oils, rich in either n‐3 polyunsaturated fatty acids (PUFA; linseed oil) or n‐6 PUFA (safflower oil) was evaluated upon antigen exposure. The fish employed in this study had been offered the diets for 18 months from the first feeding. Rainbow trout from each group were injected intraperitoneally with formalin‐killed bacteria (Aeromonas hydrophila) or were sham‐injected and observations were made 24 h later. Though the fish fed safflower oil seemed to be under relatively greater oxidative stress, the antioxidant defences (superoxide dismutase, catalase, glutathione peroxidase) were as effective as in those fed linseed oil. The humoral (alternate complement activity and lysozyme activity) and cellular (phagocytic activity and lymphocyte proliferation) immune responses were not significantly affected by the oil offered. With the exception of reactive oxygen production that was significantly greater in the linseed oil fed fish, both groups did not differ greatly in their immune responses after antigen exposure. Thus, fish fed safflower oil that was deficient in n‐3 PUFA was able to sustain most of the critical responses similar to those fed linseed oil suggesting that plant oils of both fatty acid categories were effective for this fresh water fish.  相似文献   

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