Fish and shellfish immunology reports最新文献

Scientific research into fish wellness is critical, and the concerns about crowding-related stress due to increased stocking density are inevitable. Taking this into consideration, the study defines the physiological signature of Ompok bimaculatus (Butter catfish) in a biofloc system when subjected to varying levels of stocking density. Fish (mean weight = 1.21 g ± 0.08, n = 600) were randomly stocked in 40-L glass aquaria at stocking densities of 0.5 g/L (T1), 1 g/L (T2), 1.5 g/L (T3), and 2 g/L (T4) and fed a 35% protein diet. After the 90-day trial, the physio-biochemical, molecular, and tissue-level changes were assessed. An integrated biomarker response (IBR) analysis for the key stress indicators aided us in better understanding them. There was a significant difference in blood count between T1 and T4 (total erythrocyte count, hemoglobin, and packed cell volume). T1 had higher levels of globulin and total plasma protein, but T2 had higher levels of albumin. Only in T1 did the respiratory burst and lysozyme activity appear to be higher (p < 0.05). Increased stocking densities had a significant impact on the liver function enzymes, GOT and GPT (p < 0.05). In comparison to lower densities (T1 & T2), higher stocking density (T3 & T4) was found to raise glucose and cortisol levels (p < 0.05). Antioxidant enzymes such as catalase, glutathione-S-transferase, and malondialdehyde were found to be more pronounced in lower density tissues (T1). Furthermore, the IBR plots show that lower densities have better health than higher densities. At higher stocking densities, mRNA expression of HSP70, IL-1, and IL-20 increased (p < 0.05) in kidney and liver tissues. The Nrf-2 and Tlr-9 genes were also upregulated. Also, when stocking density was increased, tissue-level histo-architectural changes were more pronounced than when stocking density was kept low. The findings of this study show that the welfare of Butter catfish cultured at high density in biofloc systems suffers from severe stress, and therefore draw more attention to the development of a species-specific standard rearing methodology in the pursuit of a profitable aqua-farming enterprise.

Studies are lacking that investigate the dietary nutrient requirements of lake whitefish (Coregonus clupeaformis), a newly farmed fish species in Ontario, Canada. Dietary levels of protein and lipid must be optimized to ensure high growth performance for the commercial success of this species. Additionally, the inclusion of insect meal in the diet may improve growth and immune response. The objective of this study was to evaluate the effects of dietary protein:lipid ratios and insect meal as a feed additive on the growth performance and hepatic immune function of juvenile lake whitefish (301 ± 10 g). A 16-week (112 day) trial was performed with five diets including a commercial control diet (BCC), and four experimental diets with high or low levels of protein (54 and 48%, respectively) and lipid (18 and 12%, respectively). The high protein dietary groups contained 5% of full-fat black soldier fly larvae (Hermetia illucens). Fish weights, viscera, liver, and blood were collected for further analysis. Specific growth rate, thermal growth coefficient and weight gain were significantly higher in fish fed with the BCC and high protein high lipid (HPHL) diets. However, viscerosomatic index was found to be significantly higher in fish fed the BCC diet, thus HPHL is more optimal for non-visceral weight gain. Higher levels of plasma phosphorus, aspartate aminotransferase and potassium indicated poor growth and stress in fish fed low lipid diets. Relative expression of HSP70, involved in cellular repair, was significantly downregulated in fish fed high lipid diets, and no effects were found on the expression of innate immune and oxidative stress genes. Also, IL8 (CXCL8) and catalase were upregulated (non-significant) in fish fed the HPHL diet with the largest weight gain. No effects of insects were found on growth, plasma biochemistry or gene expression, which suggests 5% dietary inclusion was too low. Overall, we recommend a HPHL diet for the cultivation of lake whitefish based on improved growth performance, low viscera weight, improved plasma biochemistry and downregulation of cellular repair genes.

Annual rhythms in immune function are the reflection of a crucial physiological strategy to deal with environmental stressors. The fish are pivotal animal models to study the annual rhythm and to understand the evolution of the vertebrate biological system. The current research was planned to assess the annual changes in the innate immune functions of immune cells in a teleost, Channa punctatus. Head kidney and splenic macrophage phagocytosis, superoxide generation, and nitrite release were evaluated to assess innate immunity. Cell-mediated immunity was measured through head kidney and splenic lymphocyte proliferation in presence of mitogens. The superoxide anion generation by the cells of head kidney and spleen was maximum in October. A bimodal pattern in nitrite production was observed with the first peak in November and the second in March. Cosinor analysis revealed a statistically significant annual rhythm in nitrite production. Similarly, phagocytosis and lymphocyte proliferation also showed statistically significant annual rhythms. It was concluded that animals maintain an optimum immune response in seasonally changing environments. Elevated immunity during certain times of the year might assist animals deal with seasonal environmental stressors. Further research may be focused upon measuring survival rate and reproductive success after season induced elevated immunity.

LHPP (Phospholysine Phosphohistidine Inorganic Pyrophosphate Phosphatase) is a protein histidine phosphatase that modulates a hidden posttranslational modification called histidine phosphorylation. LHPP also acts as a tumor suppressor, which plays a pivotal role in various cellular processes. However, whether LHPP participates in the regulation of invertebrate's immunity is still unknown. Here we characterized a LHPP homolog in P. vannamei (designated PvLHPP), with a 807 bp length of open reading frame (ORF) encoding a putative protein of 268 amino acids. Sequence analysis revealed that PvLHPP contains a typical hydrolase 6 and hydrolase-like domain, which was conserved from invertebrate to vertebrate. PvLHPP was ubiquitously expressed in tissues and induced in hemocyte and hepatopancreas by Vibrio parahaemolyticus, Streptococcus iniae and white spot syndrome virus (WSSV) challenge, indicating that PvLHPP participated in the immune responses. Moreover, silencing of PvLHPP followed by V. parahaemolyticus inhibited hemocyte apoptosis. This study enriches our current insight on shrimp immunity, and provides novel perspective to understand immune-regulatory role of PvLHPP.

Interleukins (ILs) are a subgroup of secreted cytokines, which are molecules involved in the intercellular regulation of the immune system. In this study, 12 IL homologs were cloned and functionally identified from obscure puffer Takifugu obscurus, and they were termed as ToIL-1β, ToIL-1, ToIL-6, ToIL-10, ToIL-11, ToIL-12, ToIL-17, ToIL-18, ToIL-20, ToIL-24, ToIL-27, and ToIL-34. Multiple alignment results showed that except for ToIL-24 and ToIL-27, other deduced ToIL proteins shared typical characteristics and structure with other known fish ILs. Phylogenetic analysis revealed that 12 ToILs were evolutionarily closely related to their counterparts in other selected vertebrates. Tissue distribution assay demonstrated that the mRNA transcripts of most ToIL genes were constitutively expressed in all tissues examined, with relatively high expression in immune tissues. Following Vibrio harveyi and Staphylococcus aureus infection, the expression levels of 12 ToILs in the spleen and liver were significantly upregulated, and their response over time varied. Taken together, these data were discussed accordingly with the ToIL expression and the immune response under the different situations tested. The results suggest that the 12 ToIL genes are involved in the antibacterial immune response in T. obscurus.

Ziziphus joazeiro Mart. is an endemic plant of the Caatinga that presents a great socioeconomic importance for the Northeast and Semiarid Region of Brazil. In view of this, this study aimed to evaluate the antibacterial activity and anxiolytic-like effects of Ziziphus joazeiro Mart leaves in adult zebrafish (Danio rerio). The characterization of the main classes of metabolites was performed through chemical reactions. The antibacterial and antibiotic potentiating activity was evaluated by broth microdilution assays. The 96 h acute toxicity, open field test and anxiety models test was evaluated in vivo on adult zebrafish. The results obtained in the phytochemical prospection evidenced the presence of flobabenic tannins, leucoanthocyanidins, flavonois, flavonones, catechins, alkaloids, steroids, and triterpenoids. EEFZJ did not show antibacterial activity for all microorganism tested (MIC ≥ 1024 µg/mL), but reduced the concentration required for bacterial growth inhibition in combination with gentamicin and norfloxacin against multidrug-resistant strains of S. aureus (SA10) and E. coli (EC06), exhibiting synergistic effect with these antibiotics (p<0.0001). In the tests in vivo, EEFZJ was found to be nontoxic, performing reduced locomotor activity and demonstrated an anxiolytic-like effect in adult zebrafish via GABAergic and Serotoninergic systems (5-HT₁, 5-HT_2A/2C and 5-HT_3A/3B).

We identified a novel immunoglobulin (Ig) heavy chain-like gene (tsIgH) expressed in the liver of the banded houndshark Triakis scyllium by preliminary transcriptomic analysis. The tsIgH gene showed less than 30% of amino acid identities to Ig genes of the shark. The gene encodes one variable domain (VH) and three conserved domains (CH1-CH3) with a predicted signal peptide. Interestingly, this protein has only one cysteine residue in a linker region between VH and CH1 other than those required for the formation of the immunoglobulin domain. Genome sequencing revealed that each of the domains was encoded by a corresponding single exon, and the exon-intron structures of the homologues are conserved in the other cartilaginous fishes. By RT-qPCR analysis, the transcript of the tsIgH gene was observed only in the liver, while that of the IgM was mainly detected in the epigonal organ, liver, and spleen. The novel Ig-heavy chain-like gene in cartilaginous fish may provide new clues to the evolution of immunoglobulin genes.

Pandanus tectorius leaf extract effect on the White-leg shrimp Penaeus vannamei tolerance against Vibrio parahaemolyticus were investigated in this study. Thirty shrimp post-larvae measured at approximately 1 cm were exposed for 24 h to 0.5, 1, 2, 3, 4, 5 and 6 g/L leaf extract and subsequently observed for survival and immune-related genes expression (Hsp70, ProPO, peroxinectin, penaeidin, crustin and transglutaminase), followed by determination of their tolerance and histological tissue profiles upon Vibrio challenge. Survival of shrimps treated with 6 g/L of leaf extract improved by up to 95% to controls. Hsp70, crustin, and prophenoloxidase mRNA levels were observed to be 8.5, 10.4, and 1.5-fold higher, respectively. Histopathological analysis of the hepatopancreas and the muscle tissues revealed major tissue degeneration in Vibrio-challenged shrimps but not in shrimps primed with P. tectorius leaf extract. Of all the dose examined, the best pathogen resistance results were obtained with a 24 h incubation of shrimp in 6 g/L P. tectorius methanolic leaf extract. The tolerance towards V. parahaemolyticus might be associated with the increased regulation of Hsp70, prophenoloxidase and crustin upon exposure to the extract, all immune-related proteins essential for pathogen elimination in Penaeid shrimp. The present study primarily demonstrated that P. tectorius leaf extract is a viable alternative for enhancing P. vannamei post-larvae resistance against V. parahaemolyticus, a major bacterial pathogen in aquaculture.

The study investigated the effects of dietary administration of β-glucan on aquaporins and antioxidative & immune gene expression in endangered golden mahseer, Tor putitora juveniles, exposed to ammonia stress. For that, fish were fed experimental diets having 0 (control/basal), 0.25, 0.5, and 0.75% β-d-glucan for five weeks and then exposed to ammonia (10 mgL⁻¹ total ammonia nitrogen) for 96 h. Administration of β-glucan differentially influenced the mRNA expression of aquaporins, anti-oxidative, and immune genes in ammonia-exposed fish. For instance, the transcript abundance of catalase and glutathione-s-transferase in gill varied significantly among the treatment groups, with the lowest levels in 0.75% β-glucan fed groups. At the same time, their hepatic mRNA expression was similar. Congruently, transcript abundance of inducible nitric oxide synthase considerably decreased in the β-glucan fed ammonia-challenged fish. Conversely, the relative mRNA expression of various immune genes viz., major histocompatibility complex, immunoglobulin light chain, interleukin 1-beta, toll-like receptors (tlr4 and tlr5) and complement component 3 remained largely unchanged in ammonia-exposed mahseer juveniles that were fed with graded levels of β-glucan. On the other hand, a significantly lower transcript level of aquaporins 1a and 3a was noticed in the gill of glucan-fed fish compared to ammonia-exposed fish that received the basal diet. However, branchial aquaporin 3b remained unaltered. Altogether, this study showed that dietary intake of 0.75% β-glucan improved resistance to ammonia stress to a certain degree, probably through activating anti-oxidative system and reducing brachial ammonia uptake.