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1.
Nocardia seriolae is the main pathogen responsible for fish nocardiosis. A mitochondrial‐targeting secretory protein (MTSP) 3141 with an N‐terminal transit peptide (TP) from N. seriolae was predicted by bioinformatic analysis based on the genomic sequence of the N. seriolae strain ZJ0503. However, the function of the MTSP3141 and its homologs remains totally unknown. In this study, mass spectrometry analysis of the extracellular products from N. seriolae proved that MTSP3141 was a secretory protein, subcellular localization research showed the MTSP3141‐GFP fusion protein co‐localized with mitochondria in fathead minnow (FHM) cells, the TP played an important role in mitochondria targeting, and only the TP located at N‐terminus but not C‐terminus can lead to mitochondria directing. Moreover, quantitative assays of mitochondrial membrane potential (ΔΨm) value, caspase‐3 activity and apoptosis‐related gene (Bcl‐2, Bax, Bad, Bid and p53) mRNA expression suggested that cell apoptosis was induced in FHM cells by the overexpression of both MTSP3141 and MTSP3141ΔTP (with the N‐terminal TP deleted) proteins. Taken together, the results of this study indicated that the MTSP3141 of N. seriolae was a secretory protein, might target mitochondria, induce apoptosis in host cells and function as a virulence factor.  相似文献   

2.
這鱼诺卡氏菌是鱼类诺卡氏菌病的主要病原,可导致鱼类慢性系统性肉芽肿疾病.這鱼诺卡氏菌全基因组序列分析发现了一个酪氨酸蛋白磷酸酶(protein tyrosine phosphtase,PTP)基因,生物信息学分析显示该基因很可能编码一个靶向定位于宿主细胞线粒体的分泌蛋白.本实验对這鱼诺卡氏菌PTP进行了基因克隆、分泌蛋白鉴定、亚细胞定位、过表达和线粒体膜电位检测,结果显示,在這鱼诺卡氏菌胞外产物中质谱鉴定到了PTP肽段,证实其为分泌蛋白.亚细胞定位研究观察到PTP-GFP融合蛋白均匀地分布在FHM细胞中,与线粒体分布不重合,说明這鱼诺卡氏菌PTP蛋白并未靶向定位于线粒体.亚细胞定位和过表达研究都显示PTP蛋白在FHM细胞中表达后,细胞核出现固缩浓染、凋亡小体等明显的细胞凋亡特征.通过线粒体膜电位检测表明,在pcDNA-PTP转染后48 h,线粒体跨膜电位被明显破坏,说明這鱼诺卡氏菌PTP很可能是一种可诱导细胞凋亡的细菌蛋白.通过对這鱼诺卡氏菌PTP开展基因克隆和功能初步研究,为进一步揭示该基因的功能和深入了解這鱼诺卡氏菌的分子致病机理奠定了基础.  相似文献   

3.
Fish nocardiosis is a chronic systemic granulomatous disease, and Nocardia seriolae is the main pathogen. The pathogenesis and virulence factors of N. seriolae are not fully understood. Secreted superoxide dismutase (SOD) may be a virulence factor found by a comparative bioinformatics analysis of the whole genome sequence of N. seriolae and the virulence factor database (VFDB). In order to determine the subcellular localization and study the preliminary function of SOD from N. seriolae (NsSOD), gene cloning, secreted protein identification, subcellular localization in fish cells, and apoptosis detection of NsSOD were carried out in this study. Subcellular localization research revealed that NsSOD‐GFP fusion proteins were evenly distributed in the cytoplasm. Furthermore, apoptotic bodies were observed in the transfected FHM cells by the overexpression of protein NsSOD. Then, assays of mitochondrial membrane potential (ΔΨm) value, caspase‐3 activity and apoptosis‐related genes (Bax, Bid, Bad and Bcl‐2) mRNA expression were conducted. The results showed that ΔΨm was decreased, and caspase‐3 was significantly activated. The mRNA expression of the Bad gene showed significant up‐regulated expression at 24 h.p.t., while Bid and Bax genes showed significant up‐regulated expression at 72 and 96 h.p.t. and anti‐apoptotic gene (Bcl‐2) was down‐regulated in NsSOD overexpressed cells. Taken together, the results indicated that the protein NsSOD might be involved in apoptosis regulation. This study may lay the foundations for further studies on the function of NsSOD and promote the understanding of the virulence factors and the pathogenic mechanisms of N. seriolae.  相似文献   

4.
Nocardia seriolae, a Gram-positive bacterium, is the main pathogen of fish nocardiosis. Protein NlpC/P60 is a cell-wall peptidase and a potential virulence factor of N. seriolae. Subcellular localization research revealed that both NlpC/P60-GFP and NlpC/P60Δsig-GFP fusion proteins were evenly distributed in the whole cell of fathead minnow (FHM) cells. Furthermore, typical apoptotic features, such as nuclear pyrosis and apoptotic bodies, were observed in the transfected FHM cells and grouper spleen cells by the overexpression of protein NlpC/P60. Then, quantitative assays of mitochondrial membrane potential (ΔΨm) value, caspase-3 activity and apoptosis-related gene (Bax, BNIP3, TNF1 and TNF6) mRNA expression were conducted. The results showed that ΔΨm was decreased, caspase-3 was significantly activated, and the mRNA expression of pro-apoptotic genes (Bax and BNIP3) and tumour necrosis factors (TNF1 and TNF6) was up-regulated in NlpC/P60-overexpressed cells. Taken together, the results indicated that the protein NlpC/P60 of N. seriolae might involve in apoptosis regulation. This study may lay the foundation for further study on the function of N. seriolae NlpC/P60 and promote the understanding of the virulence factors and pathogenic mechanism of N. seriolae.  相似文献   

5.
Enteromyxosis caused by Enteromyxum scophthalmi is one of the parasitizations with a higher economic impact on turbot, Scophthalmus maximus (L.), aquaculture. This myxosporean produces severe catarrhal enteritis with abundant inflammatory infiltrates in the lamina propria‐submucosa (LP), epithelial detachment and leucocyte depletion of the lymphohaematopoietic organs. Some advances made on the pathogenesis pointed to a role of apoptosis in the enteromyxosis. Therefore, the main aim of this work was to employ the TUNEL assay and the anti‐(active caspase‐3) immunohistochemical assay to detect apoptotic cells in both healthy and E. scophthalmi‐infected turbot in order to establish the presence and distribution of apoptotic cells during development of the disease. More apoptotic cells located within the gastrointestinal epithelium were observed in the initial stages of the infection in E. scophthalmi‐infected turbot compared with non‐infected turbot. As the infection progressed, a higher degree of apoptosis occurred in the epithelium of folds heavily parasitized. In the severely infected turbot, apoptosis was also found among the leucocytes of the intestinal inflammatory infiltrates. Moreover, the number of active caspase‐3‐positive cells in the lymphohaematopoietic organs tended to increase with disease severity. In view of the results, increased apoptosis in the epithelium may favour the scaling that occurs during enteromyxosis and cell death of leucocytes in the intestinal LP, contributing to leucocyte depletion in severe cases.  相似文献   

6.
The aim of this study was to evaluate the effects of dietary lipids on protein‐sparing and lipoprotein lipase (LPL) mRNA expression in culture using 360 juvenile soft‐shelled turtles (Pelodiscussinensis) (initial weight 4.26 ± 0.14 g). The turtles were allotted to six diets with three duplicates for 60 days. A control diet with 46% protein and 55% fishmeal (CD) and five isonitrogenous diets with 41.3% protein and 45% fishmeal (F, S, L1, L2 and L3) were used, containing the following three lipid types: fish oil, soybean oil and mixed oils (soybean oil: fish oil = 1:1). The results showed that the survival rate was not affected by dietary lipids (P > 0.05). The highest weight gain and lowest feed coefficient ratio were seen in the L3 diets (P < 0.05). Turtles fed with L2 and L3 diets had lower superoxide dismutase activities, higher alanine aminotransferase activities and higher cholesterol concentrations than those exposed to other diets (P < 0.05). Hepatic LPL activity and LPL mRNA expression were higher in the L3 diets than in the other diets (P < 0.05). Overall, there were obvious protein‐sparing effects of dietary lipids and LPL mRNA expression was stimulated by high dietary lipids in soft‐shelled turtles in this study.  相似文献   

7.
A previous proteomic study examining the plasma acute‐phase response of rainbow trout to sterile inflammation highlighted an unidentified 9.5‐kDa spot using 2D‐PAGE, which was dramatically increased. The 15 amino acid sequence obtained from this protein spot allowed rapid amplification of cDNA ends PCR to generate a 443‐bp nucleotide sequence that was 98.6% similar to type‐4 ice‐structuring protein LS‐12 from Atlantic salmon Salmo salar Linnaeus. Quantitative reverse translation PCR and an ELISA were used to measure gene expression and plasma concentrations of LS‐12 following experimental intraperitoneal injection of rainbow trout with either 106 or 108 colony‐forming units (CFU) of Flavobacterium psychrophilum. There was no significant change in the plasma concentration of LS‐12 up to 15 days post‐infection in any group. Hepatic LS‐12 gene expression was significantly reduced at 3 and 6 days (p < 0.001) post‐infection in fish injected with 108 CFU of F. psychrophilum relative to control fish, while branchial or head kidney expression was unchanged. Infected fish had significantly increased hepatic gene expression of serum amyloid A, confirming an acute‐phase response. Under the conditions used, LS‐12 is not a positive acute‐phase protein in rainbow trout.  相似文献   

8.
This study was conducted to investigate the protective effect of L‐carnitine (LC) against H2O2‐induced oxidative stress in the fathead minnow muscle cell line (FHM). The FHM cells were stimulated with 1 mM H2O2 for 1 h after LC pre‐treatment, and the cell viability and the activity and mRNA relative expression of antioxidant enzyme were measured to assess the antioxidant properties of LC. The results showed that the toxic effect of H2O2 on the viability of FHM cells was both dose‐ and time‐dependent. Furthermore, the viability of the 0.01–1 LC mM groups was significantly higher than those of the 1 mM H2O2 group. L‐carnitine protected the cells from H2O2‐induced oxidative damage, which was demonstrated by a significant reduction in the malondialdehyde and reactive oxygen species levels and increases in the intracellular total glutathione levels and the activities of total superoxide dismutase, catalase, glutathione peroxidase (GPx) and gamma‐glutamyl‐cysteine synthetase (γ‐GCS) in FHM cells pre‐treated with LC for 6 h compared with the 1 mM H2O2 group. In addition, the mRNA relative expression levels of the γ‐GCS catalytic subunit and nuclear factor nuclear factor erythroid 2‐related factor 2 were significantly higher than those of the 1 mM H2O2 group. It could be concluded that LC exerts a beneficial antioxidant effect against oxidative stress induced by H2O2 in FHM cells and that the appropriate treatment is 0.1–1 mM for 6 h in this study.  相似文献   

9.
Largemouth bass Micropterus salmoides were immunized with four different N. seriolae strains—two α-glucosidase-positive (961113, KU040801) and two α-glucosidase-negative (94260, OTTS) strains—along with Freund’s incomplete adjuvant. After primary immunization (week 0), a booster was administered at weeks 4 and 8. Nonspecific immune responses to multiple immunizations with the different N. seriolae strains were determined based on serum lysozyme activity and nitroblue tetrazolium (NBT)-positive cells in peripheral blood. The serum lysozyme activity and NBT-positive cells in peripheral blood were not significantly increased even after the two booster immunizations. Specific antibody responses against N. seriolae cells were investigated by enzyme-linked immunosorbent assay. At 4 weeks after immunization, all groups immunized with N. seriolae antigens showed significant increases in their specific antibody levels. The sera from fish immunized with different N. seriolae strains exhibited reactivity with N. seriolae sonicated antigens of 28, 30, 36 and 84 kDa by western blot analysis. After two boosters, fish were challenged with live N. seriolae to assess the vaccine’s efficacy; however, multiple injections of the N. seriolae strains did not reduce mortality, irrespective of the bacterin.  相似文献   

10.
The main objective of this study was to evaluate the effect of methionine supplementation when reducing fishmeal levels in diets for white shrimp (Litopenaeus vannamei). Tested diets consisted of a positive control with 260 g/kg fishmeal (D1), two negative controls with 100 g/kg fishmeal and no amino acid (AA) supplementation (D2) or supplemented with lysine but not methionine (D3), and four additional diets with 100g/kg fishmeal supplemented with increasing levels of DL‐Met (1.0, 2.0 or 3.0 g/kg) (D4, D5, D6) or Met‐Met (1.0 g/kg) (D7). Each diet was fed to four groups of 30 shrimp for 8 weeks at a daily rate of 70 g/kg body weight. Reduction in fishmeal from 260 g/kg down to 100 g/kg did not significantly affect survival rate, feed conversion ratio (FCR), protein efficiency ratio (PER) or protein retention efficiency (PR%) of white shrimp. However, growth performance (final body weight, FBW; weight gain, WG; specific growth rate, SGR) was reduced when dietary fishmeal level was reduced from 260 g/kg (D1) to 100 g/kg without methionine supplementation (D2). The growth performance (FBW, WG and SGR) of shrimp was significantly increased by supplementation of the 100 g/kg fishmeal diet with increasing levels of DL‐Met (p < .05). Same performance as positive control (D1) was achieved with diets containing 100 g/kg fishmeal and supplemented with 3.0 g/kg DL‐Met or 1.0 g/kg Met‐Met. The highest values of growth performance (FBW, WG and SGR) were found in shrimp fed D6 and D7 diets, which were significantly higher than those of shrimp fed D2 and D3 diets (p < .05) but without statistical differences with shrimp fed D1, D4 and D5 diets (p > .05). The highest values of whole‐body and muscle protein contents were found in shrimp fed D1 diet, which were significantly higher than those of shrimp fed all other diets (p < .05). The highest value of intestinal tract proteolytic enzyme activity was found in shrimp fed Met‐Met‐supplemented diet (D7) and followed by the positive control diet (D1) and 3 g/kg DL‐Met‐supplemented diet (D6) (p < .05). The highest values of apparent digestibility coefficients (ADCs) of dry matter and crude protein were found in Met‐Met‐supplemented diet (D7) and followed by the positive control diet (D1) (p < .05). Shrimp fed the D1 diet showed the highest value of total essential amino acid (EAA) and was significantly higher than shrimp fed D2–D3 (p < .05) but without significant difference with shrimp fed D4–D7 (p > .05). In conclusion, results showed that same performance can be achieved with diets containing 260 or 100 g/kg fishmeal supplemented with 3.0 g/kg DL‐Met or 1.0 g/kg Met‐Met. Moreover, supplementation of limiting methionine in low‐fishmeal diets seems to improve the digestive proteolytic activity, improving digestibility of dry matter and protein, and eventually to promote growth of juvenile white shrimp in fishmeal reduction diets.  相似文献   

11.
A 10‐week feeding trial was conducted to evaluate the effects of supplementing different levels of dl ‐methionyl‐dl ‐methionine (AQUAVI® Met‐Met) in plant protein–based diets on Litopenaeus vannamei. The positive control (PC) and negative control (NC) diets were designed with 20% and 8% fishmeal respectively, and other six diets were formulated with graded levels of Met‐Met from 0.05% to 0.30% with a 0.05% increment on the basis of NC diet (MM 0.05–MM 0.3). Six replicates were randomly assigned to each diet with 50 shrimp each having initial weight of 0.98 ± 0.02 g. The variation of FM concentration from 20% to 8% and supplemented with graded levels of Met‐Met did not affect the survival rate, feed conversion ratio, protein efficiency ratio, whole body and muscle proximate compositions (p > 0.05). However, diets with ≤0.20% Met‐Met supplementation resulted in significantly increased weight gain and specific growth rate, after which both parameters reached plateau. Shrimp fed the NC diet showed significantly lower total essential amino acid (EAA) content in muscle (p < 0.05). Supplementation of Met‐Met significantly improved apparent digestibility coefficients of dry matter, crude protein, lipid, phosphorus and EAAs (p < 0.05). Based on broken‐line analysis, the methionine requirement for white shrimp was estimated to be 0.87% when using Met‐Met as methionine source.  相似文献   

12.
鱼类诺卡氏菌病是一种慢性系统性肉芽肿疾病,鱼诺卡氏菌是其主要病原。鱼诺卡氏菌全基因组生物信息学分析,发现了一个可能靶向定位于宿主细胞线粒体的分泌蛋白——动力蛋白调节蛋白robl/LC7。为了对鱼诺卡氏菌robl/LC7的亚细胞定位和功能进行初步研究,实验对鱼诺卡氏菌robl/LC7进行了基因克隆、真核表达重组质粒构建、分泌蛋白鉴定、亚细胞定位、过表达和凋亡检测。结果显示,成功克隆了鱼诺卡氏菌robl/LC7基因并构建了其真核表达质粒p EGFP-robl/LC7和pc DNA-robl/LC7;鱼诺卡氏菌分泌蛋白质谱鉴定证实robl/LC7为分泌蛋白;亚细胞定位研究显示robl/LC7-GFP融合蛋白呈全细胞分布,不与线粒体共定位;凋亡检测发现robl/LC7过表达能诱导FHM细胞凋亡。研究表明,鱼诺卡氏菌robl/LC7是一个不与线粒体共定位的分泌蛋白,其可能通过参与细胞凋亡调控,协助鱼诺卡氏菌在宿主体内生存和免疫逃避,并在鱼诺卡氏菌的致病过程中具有重要作用。  相似文献   

13.
Insulin‐like growth factor (IGF) plays a key role in the complex system that regulates bony fish growth, differentiation, and reproduction. In the current study, recombinant tongue sole IGF‐1 and IGF‐2 were obtained using the Pichia pastoris expression system and their comparative bioactivities were investigated. Tricine–SDS–PAGE and western blot analysis showed that the recombinant tongue sole IGFs were secreted into the culture medium and had a molecular weight of 8.7 kDa. The optimal incubation time and pH for recombinant expression of IGFs were 36 hr and 5.0 respectively. Functional analysis demonstrated that both recombinant tongue sole IGF‐1 and IGF‐2 significantly promoted cell proliferation of MFC‐7 in vitro. In addition, the recombinant tongue sole IGF‐1 and IGF‐2 proteins could suppress hepatic mRNA levels of igf‐1 and igf‐2 in vitro, which showed that they have similar physiological functions. Taken together, the biologically active recombinant tongue sole IGF‐I and IGF‐II proteins will allow us to further investigate their physiological roles in growth regulation of this species. Furthermore, the present results also hinted at the potential application of these two recombinant IGF‐I and IGF‐II proteins into the tongue sole farming industry.  相似文献   

14.
The current study aimed to investigate the effects of dietary soybean β‐conglycinin on growth performance and intestine apoptosis in juvenile grass carp (Ctenopharyngodon idella). For fish fed with the 80 g β‐conglycinin/kg diet for 7 weeks, the specific growth rate and feed intake were decreased. In the proximal intestine, dietary β‐conglycinin did not induce DNA fragmentation, tended to decrease the reactive oxygen species (ROS) content, and decreased ROS‐generating enzyme (NADPH oxidase [NOX]) activity. Subsequently, in the mid‐intestine, dietary β‐conglycinin caused DNA fragmentation, tended to increase the ROS content, increased caspase‐3, caspase‐8 and caspase‐9 activities, upregulated the mRNA levels of proapoptotic molecules (apoptotic protease‐activating factor‐1 [Apaf1] and Bcl‐2‐associated X protein [BAX]) and mitogen‐activated protein kinase (MAPK)‐related signal molecules (Jun N‐terminal kinase (JNK) and p38 MAPK) and increased the protein levels of p38 MAPK and phospho‐p38 MAPK. Moreover, in the distal intestine, dietary β‐conglycinin induced DNA fragmentation, elevated NOX activity and the ROS content and increased caspase‐3, caspase‐8 and caspase‐9 activities, death ligand (TNF‐α) mRNA expression level, and p38 MAPK and phospho‐p38 MAPK protein levels. In summary, dietary soybean β‐conglycinin suppressed fish growth and inconsistently caused apoptosis among the different intestinal segments which was partially associated with ROS‐mediated MAPK signalling.  相似文献   

15.
Pseudomonas plecoglossicida NB2011, the causative agent of visceral granulomas disease in farmed Larimichthys crocea in China, encodes a predicted type three effector PP_ExoU, a homolog of the cytotoxin ExoU of Pseudomonas aeruginosa. In this study, secretion of PP_ExoU was tested in various broth, the protein was expressed with the pET30a prokaryotic system, the phospholipase A (PLA) activity of the recombinant protein was determined with fluorogenic phospholipid substrates, fusion expression with green fluorescent protein in transfected HeLa cells was investigated, and the lactate dehydrogenase (LDH) level was measured. The results showed the protein was type three secreted in several media; the recombinant protein displayed significant PLA1 activity with ubiquitin. Fluorescence was observed on the cell membrane and scattered in the cytoplasm of HeLa cells expressing catalytic wild‐type PP_ExoU, blebbing and stretching developed in the cell membranes indicating of membrane damage. Fluorescence scattered in the cytoplasm of cells expressing the catalytic inactive protein. A significant LDH level was detected in HeLa cells expressing wild‐type PP_exoU, but not in the Ser/Asp‐mutated protein, suggestion mutation of predicted catalytic residues abolished the PLA activity. This is the first report on the function of a secreted type three protein from P. plecoglossicida.  相似文献   

16.
Streptococcus agalactiae is a major pathogen of tilapia causing significant economic losses for the global aquatic industry yearly. To elucidate the role of cel‐EIIB protein‐mediated phosphotransferase systems (PTS) in the virulence regulation of S. agalactiae, cel‐EIIB gene deletion in a virulent strain THN0901 was achieved by homologous recombination. The cellobiose utilization of △cel‐EIIB strain was significantly decreased relative to S.a.THN0901 strain incubating in LB with 10 mg/ml cellobiose (p < 0.05). The biofilm formation ability of △cel‐EIIB strain was also significantly decreased when cultured in BHI medium (p < 0.05). Under a lower infection dose, the accumulative mortality of tilapia caused by △cel‐EIIB strain was dramatically decreased (20%), of which S.a.THN0901 strain and △cel‐EIIB::i strain were 53.33% and 50%, respectively. The competition experience using tilapia model indicated the invasion and colonization ability of △cel‐EIIB strain was significantly weaker than that of S.a.THN0901 strain (p < 0.05). Compared to △cel‐EIIB::i strain, the mRNA expression of csrS, csrR, rgfA, rgfC, bgrR and bgrS was significantly downregulated in △cel‐EIIB strain (p < 0.05). In conclusion, cel‐EIIB protein‐mediated cel‐PTS not only contributes to biofilm formation and virulence regulation, but also plays an important role in the invasion and colonization of S. agalactiae.  相似文献   

17.
The γ‐aminobutyrate type A receptor‐associated protein (GABARAP) is a ubiquitin‐like modifier implicated in membrane trafficking and fusion events involving the γ‐aminobutyrate type A receptor, autophagy and apoptosis. In this study, the gene encoding GABARAP was cloned from swimming crab Portunus trituberculatus (PtGABARAP) based on the expression sequence tag (EST). The full‐length cDNA of 664 bp includes a 5′ untranslated region (UTR) of 87 bp, a 3′ UTR of 223 bp with a poly(A) tail, and an open reading frame (ORF) of 354 bp encoding a polypeptide of 117 amino acids with a predicted molecular weight of 13.96 kDa. The deduced amino acid sequence shares high similarity (93%–100%) with GABARAPs from other species and includes a conserved Atg8 domain. In a phylogenetic analysis PtGABARAP clustered with GABARAPs from other species, and more widely with other GABARAP family proteins. The impact of elevated ocean acidification (OA) on P. trituberculatus behaviours was investigated, and real‐time RT‐PCR revealed that PtGABARAP expression was up‐regulated after OA exposure. Ocean acidification also caused crabs anxiety‐like behaviours, like the shoal average speed increase, preference for dark environment (scototaxis) and fast exploration. The results indicated that GABARAP might be involved in the interactions of GABAA receptors and elevated‐CO2 seawater.  相似文献   

18.
The invasive fish pathogen Edwardsiella tarda is common in aquatic environments and causes the environmentally and economically destructive emphysematous putrefactive disease called edwardsiellosis. In order to understand the organism's infection pathway, medaka larvae (Oryzias latipes) were immersion‐infected with E. tarda labelled with green fluorescence protein (GFP) and then visualized in three dimensions under confocal laser microscopy and light‐sheet fluorescence microscopy. Confocal microscopy revealed GFP‐labelled E. tarda in the mouth, head, gill bridges, gill cover, skin, membrane fin, gastrointestinal tract and air bladder, and in the caudal vein, somite veins, caudal artery and caudal capillaries. Light‐sheet microscopy additionally showed GFP‐labelled E. tarda in the pharyngeal cavity, muscle of the pectoral fin and cardiac atrium and ventricle. These findings suggest that during its infection of fish, E. tarda initially adheres to, and invades, the epithelial cells of the skin, gills and gastrointestinal tract (through the pharyngeal cavity); E. tarda then enters the blood vessels to access organs, including the air bladder and heart.  相似文献   

19.
A 30‐day experiment was conducted to investigate the effects of long‐term low‐salinity stress on the growth performance and osmotic related chlorine ion channel ligand regulation: gamma‐aminobutyric acid (GABA) content and GABAA receptor‐associated protein (GABARAP) expression in Portunus trituberculatus. The salinity levels of both the control group and the experimental group were 30 and 12 psu respectively. After rearing for 30 days, the specific growth rate and survival rate were compared between the two groups, and salinity 6 psu was used to test the salinity tolerance. The results were as follows: (a) Both the specific growth rate and survival rate were significant lower in the experimental group (p < 0.05) after 30 days; (b) After challenge with salinity 6 psu for 72 hr, the crabs of experimental group had a 100% survival rate, whereas the crabs of the control group were all dead within 48 hr; (c) The content of GABA and the gene expression level of GABARAP in experimental group were significant different from control group (p < 0.05) after challenge via salinity 6 psu. In the control group, the GABA content increased rapidly from 9.96 ± 2.09 to 42.00 ± 5.94 µg/g; however, in the experimental group, it only increased to 27.82 ± 2.55 µg/g; the gene expression of GABARAP in the experimental group increased to the maximum at 24 hr, then decreased and stabilized at 48 hr, suggesting that GABA and GABARAP were trigged during the early stage of low‐salinity stress resistance.  相似文献   

20.
Nannochloropsis oculata (Eustigmatophyceae) is a marine microalga of great biotechnological interest, mainly due to its large production of lipids containing polyunsaturated fatty acids. In addition, this species presents a wide range of commercial interest pigments, such as zeaxanthin, beta‐carotene, and other xanthophylls, with potential for several industrial applications. However, most of the research concerning pigment production by N. oculata has been conducted by employing high‐cost laboratorial growth media, which makes large‐scale pigment production using these microalgae impractical. Considering the high interest and commercial value in microalgae pigments, this study investigates the feasibility of producing pigments by N. oculata using five different low‐cost growth media (fertilizers and aquaculture effluents). Nutrient (ammonia, nitrite and phosphate) concentrations, cell abundance, biomass, and the concentration/composition of pigments were measured. The pigment profile of N. oculata showed chlorophyll‐a as the dominant pigment, along with violaxanthin, vaucheraxanthin, and lower concentrations of antheraxanthin, zeaxanthin and beta‐carotene. Although the highest biomass (516.4 ± 76.71 mg/L) and pigment content (0.98 mg/g) were achieved in the laboratory media (f/2), the low‐cost media (containing ammonium sulfate, calcium superphosphate and urea) revealed a great potential for the production of pigments, specially chlorophyll‐a, violaxanthin and zeaxanthin, due to the high pigment content per unit of biomass.  相似文献   

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