2,3,7,8-TCDD对稀有鮈鲫幼体超微结构影响的观察

国家自然科学基金29607004

Effect of high dietary starch levels on the growth performance, blood chemistry and body composition of gibel carp (Carassius auratus var. gibelio)

An 8-week growth trial was carried out in a semi-recirculation system to investigate the effect of high dietary starch levels on the growth performance, blood chemistry, starch utilization and body composition of gibel carp (Carassius auratus var. gibelio). Five isonitrogenous and isocarloric experimental diets were formulated to contain different starch levels (24%, 28%, 32%, 36% and 40% respectively). Triplicate groups of fish (24 fish per tank with an average body weight, of 8.5 g) were assigned to each diet. The results showed that dietary carbohydrate levels significantly affected the growth performance, hepatopancreatic lipid content, pyruvate kinase (PK) activity and whole-body lipid content. Growth performance, body crude lipid and plasma glucose concentrations showed a decreasing trend with an increase in dietary starch from 24% to 40%. Pyruvate kinase activities and hepatopancreatic lipid content showed an increasing trend with the dietary starch increasing from 24% to 32%, and then a decreasing trend with the dietary starch increasing from 32% to 40%. No significant difference in the hepatopancreatic hexokinase (HK) activity, plasma triglyceride contents, body crude protein, ash and calcium (Ca) and phosphorus (P) contents was observed between different treatments. In conclusion, higher dietary starch levels (32-40%) significantly (P < 0.05) decreased the growth of gibel carp in the present study.

Molecular characterization and expression profiles in response to bacterial infection of Chinese soft-shelled turtle interleukin-8 (IL-8), the first reptilian chemokine gene

In this study, an IL-8 homologue has been cloned and identified from a reptile, Chinese soft-shelled turtle for the first time. The full-length cDNA of turtle IL-8 was 1188 bp and contained a 312 bp open reading frame (ORF) coding for a protein of 104 amino acids. The chemokine CXC domain, which contained Glu-Leu-Arg (ELR) motif and four cysteine residues, was well conserved in turtle IL-8. The 4924 bp genomic DNA of turtle IL-8 contained four exons and three introns. Phylogenetic analysis showed that the amino acid sequence of turtle IL-8 clustered together with birds. RT-PCR analysis showed that turtle IL-8 mRNA was constitutively expressed liver, spleen, kidney, heart, blood and intestine tissues of control turtles. Real-time quantitative PCR analysis further indicated that the turtle IL-8 mRNA expression was apparent in various tissues at 8 h and up-regulated significantly during 8 h-7 d after Aeromonas hydrophila infection. The present studies will help us to understand the evolution of IL-8 molecule and the inflammatory response mechanism in reptiles. (C) 2009 Elsevier Ltd. All rights reserved.

Effects of dietary manganese on growth and tissue manganese concentrations of juvenile gibel carp, Carassius auratus gibelio

A 68-day growth trial was conducted in a flow-through system to determine the effect of dietary manganese levels on growth and tissue manganese concentration of juvenile gibel carp (Carassius auratus gibelio). Seven purified diets containing 7.21, 8.46, 9.50, 10.50, 13.03, 19.72 and 22.17 mg manganese (as manganic sulfate) per kilogram diet were fed to triplicate groups of fish (initial weight 3.21 +/- 0.01 g). The results showed that dietary manganese levels did not significantly affect feed intake of the fish. Specific growth rate, feed efficiency, total hepatic superoxide dismutase activity, carcass and skeletal manganese concentration increased significantly with increased dietary manganese(P < 0.05) while condition factor decreased significantly(P < 0.05). It was concluded that dietary requirement of manganese was 13.77 mg Mn per kilogram diet. Carcass and skeletal manganese concentration could also be used to evaluate the manganese requirement. Total hepatic superoxide dismulase activity was not a sensitive indicator for dietary requirement.

Tissue distribution and depuration of the extracted hepatotoxic cyanotoxin microcystins in crucian carp (Carassius carassius) intraperitoneally injected at a sublethal dose

An acute toxicity experiment was conducted by intraperitoneal injection with a sublethal dose of extracted microcystins (MCs), 50 mu g MC-LR (where L = leucine and R = arginine) equivalent/kg body weight (BW), to examine tissue distribution and depuration of MCs in crucian carp (Carassius carassius). Liver to body weight ratio increased at 3, 12, 24, and 48 h postinjection compared with that at 0 h (p < 0.05). MC concentrations in various tissues and aquaria water were analyzed at 1, 3, 12, 24, 48, and 168 h postinjection using liquid chromatography coupled with mass spectrometry (LC-MS). The highest concentration of MCs (MC-RR + MC-LR) was found in blood, 2 -270 ng/g dry weight (DW), followed by heart (3 -100 ng/g DW) and kidney (13 -88 ng/g DW). MC levels were relatively low in liver, gonad, intestine, spleen, and brain. MC contents in gills, gallbladder, and muscle were below the limit of detection. Significant negative correlation was present between MC-RR concentration in blood and that in kidney, confirming that blood was important in the transportation of MC-RR to kidney for excretion. Rapid accumulation and slow degradation of MCs were observed in gonad, liver, intestine, spleen, and brain. Only 0.07% of injected MCs were detected in liver. The recovery of MCs in liver of crucian carp seemed to be dose dependent.

Elevated levels of urinary 8-hydroxy-2'-deoxyguanosine in male electrical and electronic equipment dismantling workers exposed to high concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans, polybrominated diphenyl ethers, and polychlorinated biphenyls

To investigate the occupational exposure levels to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs), indoor dust (n = 3) in workshops and hair samples from male workers (n = 64) were collected at two electrical and electronic equipment waste (E-waste) dismantling factories located in the LQ area in east China in July 11-13, 2006. Pre- and postworkshift urines (64 of each) were also collected from the workers to study oxidative damage to DNA using 8-hydroxy-2'-deoxyguanosine (8-OHdG) as a biomarker. The concentrations of PCDD/Fs, PCDD/F-WHO-TEQs, PBDEs, PCBs and PCB-WHO-TEQs were (50.0 +/- 8.1) x 10(3), 724.1 +/- 249.6, (27.5 +/- 5.8) x 10(6), (1.6 +/- 0.4) x 10(9), (26.2 +/- 3.0) x 10(3) pg/g dry weight (dw) in dust, and (2.6 +/- 0.6) x 10(3), 42.4 +/- 9.3, (870.8 +/- 205.4) x 10(3), (1.6 +/- 0.2) x 10(6), 41.5 +/- 5.5 pg/g dw in hair, respectively. The homologue and congener profiles in the samples demonstrated that high concentrations of PCDD/Fs, PBDEs, and PCBs were originated from open burning of E-waste. The 8-OHdG levels were detected at 6.40 +/- 1.64 mu mol/mol creatinine in preworkshift urines. However, the levels significantly increased to 24.55 +/- 5.96 mu mol/mol creatinine in postworkshift urines (p < 0.05). Then, it is concluded that there is a high cancer risk originated from oxidative stress indicated by the elevated 8-OHdG levels in the E-waste dismantling workers exposed to high concentrations of PCDD/Fs, PBDEs, and PCBs.

The biological effects of rainbow trout (Oncorhynchus mykiss) recombinant interleukin-8

In this report, recombinant interieukin-8 (rIL-8) was produced and its activity tested for the first time in fish. The rainbow trout rIL-8 was produced in Escherichia coli and purified using a 6xHis tag at the N-terminus. The rIL-8 induced a dose-dependent migration of head kidney leukocytes at concentrations from 0.1 to 10 ng/ml, with a peak response at 1 ng/ml. Trout rIL-8 also had a significant effect on superoxide production by head kidney cells, with maximal, activity at 0.1 and 1 ng/ml. When injected intraperitoneally into trout, rIL-8 had a clear effect on total leukocyte number in the peritoneal cavity, with increasing doses (up to 5 mu g) eliciting more cells. Of three leukocyte types distinguished, neutrophils were the dominant cell type, especially at higher rIL-8 concentrations. In contrast, the proportion of macrophages and lymphocytes decreased with rIL-8 administration, suggesting that they were not attracted at the same rate as neutrophils. (C) 2007 Elsevier Ltd. All rights reserved.

Effect of dietary carbohydrate-to-lipid ratios on growth and feed utilization in Chinese longsnout catfish (Leiocassis longirostris Gunther)

An 8-week growth trial was carried out in a semi-recirculation system at 26 +/- 0.5 degrees C to investigate the optimal dietary carbohydrate-to-lipid (CHO:L) ratio for carnivorous Chinese longsnout catfish (Leiocassis longirostris Gunther). Triplicate tanks of fish were assigned to each of five isocaloric and isonitrogenous diets with different carbohydrate-to-lipid ratios (0.75, 1.48, 1.98, 2.99 and 5.07). The results showed that a higher specific growth rate (SGR) and feed rate (FR) were observed in the fish fed diet ratios of 1.98 CHO:L (P < 0.05). Overloading dietary carbohydrate (5.07 CHO:L ratio) caused skeletal malformations. Apparent digestibility of dry matter (ADC(d)) significantly increased with dietary CHO:L ratio (P < 0.05), while significantly higher apparent digestibility of protein (ADC(p)) and apparent digestibility of energy (ACD(e)) was observed only in the 1.98 CHO:L group (P < 0.05). Whole body contents of dry matter, lipid and energy significantly increased as the CHO:L ratio decreased (P < 0.05). The hepatosomatic index (HSI) was highest at 1.98 CHO:L ratio (P < 0.05). Highest dietary CHO:L ratio resulted in lower liver glycogen, liver lipid, plasma glucose and plasma triacylglycerol (P < 0.05), whereas there was no significant difference in plasma total cholesterol (P > 0.05). High dietary CHO:L ratio caused pathological changes in fish morphology and liver histology. Based on maximum growth, the optimal carbohydrate-to-lipid ratio was 1.98 for Chinese longsnout catfish.

Characterization of novel microsatellite loci in rare minnow (Gobiocypris rarus) and amplification in closely related species in Gobioninae

Rare minnow (Gobiocypris rarus) is an endangered small fish endemic to upper reach of the Yangtze River. From a (GT)n enriched genomic library, 32 microsatellites were isolated and characterized. Nineteen of these loci were polymorphic in a test population with alleles ranging from 2-7, and observed and expected heterozygosities from zero to 0.8438, and 0.2679 to 0.8264, respectively. In the cross-species amplifications, 13 out of 19 polymorphic loci were found to be also polymorphic in at least one of the 7 closely related species of the subfamily Gobioninae. These polymorphic microsatellite loci should provide sufficient level of genetic diversity to evaluate the fine-scale population structure in rare minnow and its closely related species for the conservation purpose.

Dietary methionine requirement for juvenile rockfish, Sebastes schlegeli

A 65-day growth trial was conducted at 19.5 degrees C to determine the optimal dietary methionine for juvenile rockfish, Sebastes schlegeli. Semipurified diets were formulated to be isonitrogenous and isoenergetic. Fish meal was used as intact protein source and crystal amino acid was used as a part of dietary protein. Six experimental diets were formulated to contain 5.8, 10.8, 15.8, 20.8, 25.8 and 30.8 g kg(-1) dietary methionine. The results showed that dietary methionine significantly affected specific growth rate, weight gain, food conversion ratio, protein productive value (PPV), energy retention efficiency, carcass index and body composition. No significant difference was found in hepatosomatic index. The dietary methionine requirement for maximum growth was 13.7 g kg(-1) dry matter or 28.0 g kg(-1) of dietary protein when cystine content was 1.2 g kg(-1) dry matter.

Effects of age and dietary protein level on digestive enzyme activity and gene expression of Pelteobagrus fulvidraco larvae

The present research studied the effects of age and dietary protein level on pepsin, trypsin and amylase activity and their mRNA level in Petteobagrus fulvidraco larvae from 3 to 26 days after hatch (DAH). Three DAH larvae were fed three isoenergetic diets, containing 42.8% (CP 43), 47.3% (CP 47) and 52.8% (CP 53) crude protein. Live food (newly hatched Artemia, unenriched) was included as a control. The effects of age on enzyme activity and mRNA were as follows: pepsin and trypsin activity in all treatment groups showed a significant (P < 0.05) increase at the beginning and decrease later although the timing of decrease was not the same among treatment groups and between the digestive enzymes. Pepsin and trypsin mRNA level followed the pattern of their respective enzyme changes. Age significantly affected amylase activity (P < 0.05) while age had no effect on amylase mRNA during the experimental period. The four diets significantly (P < 0.05) affected activity and mRNA level of pepsin and trypsin. Diets did not affect amylase activity or mRNA level. These results suggest that the effects of age on pepsin and trypsin gene expressions are at the transcriptional level. Dietary protein level does affect pepsin and trypsin gene expression in the early life of P. fulvidraco. There were no transcriptional effects on amylase gene expression. (c) 2005 Elsevier B.V. All rights reserved.

Effect of dietary carbohydrate sources on growth performance and utilization for gibel carp (Carassius auratus gibelio) and Chinese longsnout catfish (Leiocassis longirostris Gunther)

The nutritional function of monosaccharides, disaccharides and polysaccharides for omnivorous gibel carp and carnivorous Chinese longsnout catfish were investigated and the ability of these two species to utilize carbohydrates was compared. For each species, triplicate groups of fish were assigned to each of five groups of isoenergetic and isonitrogenous experimental diets with different carbohydrate sources: glucose, sucrose, dextrin, soluble starch (acid-modified starch) and alpha-cellulose. The carbohydrates were included at 60 g kg(-1) in Chinese longsnout catfish diets and at 200 g kg(-1) in gibel carp diets. A growth trial was carried out in a recirculation system at 27.8 +/- 1.9 degrees C for 8 weeks. The results showed that fish with different food habits showed difference in the utilization of carbohydrate sources. For gibel carp, better specific growth rate (SGR) and feed efficiency (FE) were observed in fish fed diets containing soluble starch and cellulose, but for Chinese longsnout catfish, better SGR and FE were observed in fish fed diets containing dextrin and sucrose. Apparent digestibility coefficient of dry matter (ADC(d)) and apparent digestibility coefficient of energy (ADC(e)) were significantly affected by dietary carbohydrate sources in gibel carp. ADC(d) and ADC(e) significantly decreased as dietary carbohydrate complexity increased in Chinese longsnout catfish except that glucose diet had medium ADC(d) and ADC(e). In both species, no significant difference of apparent digestibility coefficient of protein was observed between different carbohydrate sources. Dietary carbohydrate sources significantly affected body composition, and liver phosphoenolpyruvate carboxykinase (PEPCK), pyruvate kinase (PK), glucose 6-phosphate dehydrogenase (G6PD) and malic enzyme (ME) activities also varied according to dietary carbohydrate complexity. Fish with different food habits showed different abilities to synthesize liver glycogen, and the liver glycogen content in gibel carp was significantly higher than in Chinese longsnout catfish. The influence of carbohydrate source on gluconeogenesis and lipogenesis was also different in the two fish species.

Partial and total replacement of fishmeal with poultry by-product meal in diets for gibel carp, Carassius auratus gibelio Bloch

Triplicate groups of gibel carp Carassius auratus gibelio Bloch (initial body weight: 4.89 g) were fed for 8 weeks at 24.8-30.8 degrees C with nine isonitrogenous and isoenergetic diets. The control diet (F1) used white fishmeal (FM) as the sole protein source. In the other eight diets (F2-F9), 40.5-100% of FM protein was substituted by poultry by-product meal (PBM) at 8.5% increments. The specific growth rate (SGR), feed efficiency ratio, protein efficiency ratio, protein retention efficiency and energy retention rate for fish fed PBM diets (F2-F9) were all higher, but not always significantly, than those for fish fed F1. All apparent digestibility coefficients for fish fed PBM diets were lower than those for fish fed F1. Fish fed F1 had a significantly higher hepatosomatic index value than fish fed PBM diets (P < 0.05). No significant (P > 0.05) effect of diet was found in whole-body moisture and fat content. Whole-body protein and energy content for fish fed PBM diets were slightly higher than that for fish fed F1. The optimal replacement level of FM by PBM was estimated by second-order polynomial regression to be 66.5% in protein.

Effects of 2,3,7,8-TCDD and benzo[a]pyrene on modulating vitellogenin expression in primary culture of crucian carp (Carassius auratus) hepatocytes

Vitellogenin (Vtg) is the precursor of yolk protein. Its expression and secretion are estrogen-regulated and are crucial for oocyte maturation. An in vitro xenoestrogen screening model was established by measuring Vtg induction in cultured primary hepatocytes from crucian carp. Vtg production was detected by biotin-avidin sandwich ELISA method while Vtg and cytochrome P4501A1 (CYP1A1) mRNA induction were measured by semi- quantitative PCR-primer dropping technique. Vtg and Vtg mRNA were dose-dependently induced by diethylstilbestrol (DES, 0.2-200 ng/mL) in hepatocytes of crucian carp. Co-treatment of the DES-induced hepatocytes with either 2,3,7,8-TCDD (TCDD, 0.1-4 pg/mL) or benzo[a]pyrene (B[a]P, 5-1000 ng/mL) resulted in a reduction of Vtg production and an increment of CYP1A1 mRNA expression both in a dose dependent manner, indicating the anti-estrogenic effects of the compounds. However, at lower tested concentrations, TCDD (0.1, 0.2 pg/mL), B[a]P (5 ng/mL) seemed to have a potentiating effect on Vtg expression and secretion, although by their own these compounds had no observable estrogenic effect on Vtg induction. Tamoxifen (a selective estrogen receptor modulators, 1 nmol/L-1 mumol/L), and P-naphtho-flavone (beta-NF, an aryl hydrocarbon receptor inducing compounds, 2.5-1000 ng/mL) also were employed to study the possible interactions in DES-induced Vtg expression. In co-treatment of the DES-induced hepatocytes with beta-NF or tamoxifen, the decrease in Vtg production did parallel induction of CYP1A1 for beta-NF, but tamoxifen inhibited Vtg induction did not parallel induced CYP1A1 expression in all test concentrations. On the contrary, it was found that in co-treatment of the TCDD-induced hepatocytes with DES, TCDD induced CYP1A1 mRNA production was inhibited by DES also. These results implicated a possible cross talk between estrogen receptor- and aryl hydrocarbon receptor-mediated pathways in the hepatocytes.

Effect of replacement of dietary fish meal by meat and bone meal and poultry by-product meal on growth and feed utilization of gibel carp, Carassius auratus gibelio

Triplicate groups of gibel carp Carassius auratus gibelio (initial body weight: 5.25 +/- 0.02 g) were fed for 8 weeks at 20-25 degreesC on five isonitrogenous (crude protein: 400 g kg(-1)) and isoenergetic diets (gross energy: 17 kJ g(-1)). Meat and bone meal (MBM) or poultry by-product meal (PBM) were used to replace fish meal at different levels of protein. The control diet contained fish meal as the sole protein source. In the other four diets, 150 or 500 g kg(-1) of fish meal protein was substituted by MBM (MBM15, MBM50) or PBM (PBM15, PBM50). The results showed that feeding rate for the MBM50 group was significantly higher than for other groups except the PBM50 group (P < 0.05). Growth rate in the MBM15 group was significantly higher than that in the control (P < 0.05), while there was no significant difference in growth between the control and other groups (P > 0.05). Feed efficiency and protein efficiency ratio in MBM50 was significantly lower while that in MBM15 was significantly higher (P < 0.05). Replacement of fish meal by MBM at 500 g kg(-1) protein significantly decreased apparent dry matter digestibility (ADC(D)) and gross energy (ADC(E)) while apparent protein digestibility (ADC(P)) was significantly decreased by the replacement of MBM or PBM (P < 0.05). The results suggest that MBM and PBM could replace up to 500 g kg(-1) of fish meal protein in diets for gibel carp without negative effects on growth while 150 g kg(-1) replacement by MBM protein improved feed utilization.