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1.
A study was conducted to determine the dietary iron requirement of fingerling Atlantic salmon Salmo salar L. During the first 4 weeks of the experiment, fish with an initial weight of 5 g were fed a casein–gelatine-based purified diet which contained 11 mg iron kg?1. Thereafter duplicate tanks (200 fish in each) were fed the casein–gelatine purified diets containing supplemental iron levels of 0, 10, 20, 30, 40, 60, 100, 200 or 400 mg iron kg?1 (added as FeSO?4* 7H2O) for 12 weeks. Weight gain, body length and mortality were monitored. Liver iron and ascorbic acid concentration were analysed in addition to whole-body iron, manganese and zinc concentration. Several haematological parameters were also measured. There were no significant differences in weight gain and survival of salmon fed diets containing different iron levels. Haematological values, hepatic and whole-body iron concentrations were, however, significantly affected by the dietary iron content. Liver vitamin C concentration decreased with increasing dietary iron levels. Dietary supplementation with iron significantly reduced whole-body manganese, but no effect of dietary iron on whole-body zinc was found. Based on haematology and hepatic iron concentration, the iron requirement of Atlantic salmon was determined to be between 60 and 100 mg iron kg1.  相似文献   

2.
Atlantic salmon, Salmo salar L., with mean initial weight of 60 g were fed a diet based on cod muscle meal supplemented with elemental iron, iron sulphate or haem-bound iron in concentrations of 0, 25, 50, 100, 500 and 1500 mg iron kg?1 for 8 weeks. No significant differences in growth or mortality were found, except in fish fed 1500 mg haem iron kg?1, which showed reduced growth. In fish fed diets supplemented with elemental iron below 1500 mg iron kg?1, blood haemoglobin and hepatic iron concentration decreased compared with fish fed the unsupplemented diet. Fish fed diets supplemented with iron sulphate showed increased blood haemoglobin and hepatic iron concentrations between 25 and 100 mg iron kg?1. Fish fed diets supplemented with haem-bound iron showed increased hepatic iron at all dietary iron levels, while blood haemoglobin concentration decreased in the group fed 1500 mg haem iron kg?1. The bioavailability of haem iron relative to sulphate iron was calculated by the slope ratio method to be 239% and 148% using blood haemoglobin and hepatic iron, respectively. Relative bioavailability of elemental iron was zero when dietary supplementation levels were between 25 and 500 mg iron kg?1, while a small part was utilized when 1500 mg elemental iron kg?1 was supplemented. Additions of 500 and 1500 mg haem-bound iron kg?1 resulted in a complete loss of ascorbic acid in these diets. When these groups were discounted, no significant relationship between hepatic iron and hepatic ascorbic acid was found. There was no significant effect of dietary iron on whole-body manganese concentration and only a weak effect on whole-body zinc concentration. No significant correlations between dietary iron and hepatic copper concentration were found in any of the dietary treatments. This study also showed that the level of inorganic iron supplementation may be reduced by inclusion of 20 g blood meal kg?1 in the diet.  相似文献   

3.
The experiment was designed to investigate the dietary factors that might enhance or interfere with astaxanthin (Ax) absorption in salmon including potentially interfering factors such as certain carotenoids (zeaxanthin and lutein), plant sterols, fibre and enhancing compounds such as cholesterol and vitamin E. Two hundred and eighty‐eight salmon (778 ± 78 g) were reared in sea water under controlled conditions and fed practical experimental diets. The experimental diets were supplemented with 40 mg Ax kg?1, in addition to various dietary factors, including cholesterol (2%), vitamin E (450 IU kg?1), wheat bran (5%), lutein (40 mg kg?1), zeaxanthin (40 mg kg?1) and phytosterol (2%). After 26 days of feeding, blood was collected and plasma was separated to determine the plasma Ax concentration. Ax was not detected in the plasma of fish fed the non‐pigmented diet. Fish fed diet containing 2% cholesterol significantly improved Ax absorption, which was reflected in the higher Ax concentration in plasma of Atlantic salmon. Other supplements including vitamin E, wheat bran, lutein, zeaxanthin and phytosterols in diet had no significant effect on plasma Ax concentration . Fish fed diet containing 2% cholesterol significantly increased cholesterol concentration in fish plasma. Phytosterol had no benefit to lower cholesterol plasma level in fish fed 2% phytosterol‐supplemented diet.  相似文献   

4.
Atlantic salmon, Salmo salar L., were fed nine experimental diets containing from 0 to 200 mg astaxanthin per kg?1 for six time periods, ranging from 3 to 21 months, in sea cages at Matre Aquaculture Research Station, Matredal, Norway. The sampled fish had an initial mean weight of 115 g and reached a weight of 3.2 kg at the termination of the experiment. Every third month, 10 fish from each dose and time group were sampled and the astaxanthin concentration in the flesh determined. The amount of astaxanthin in the flesh ranged from 0.7 to 8.9 mg kg?1 at the termination of the experiment. This paper discusses deposition of astaxanthin in the flesh of Atlantic salmon in relation to dietary carotenoid levels in the 0–200 mg kg?1 range and feeding times of 3–21 months. Under the conditions of this experiment, no significant effect on astaxanthin deposition rate could be achieved by increasing the astaxanthin level above 60 mg kg dry feed?1. Atlantic salmon should be fed astaxanthin-supplemented diets during the whole seawater stage in order to obtain maximal astaxanthin level in the flesh.  相似文献   

5.
Antarctic krill (Euphausia superba) and other marine zooplankton may contain high levels of fluoride. The aim of the present experiment was to determine whether dietary fluoride from Antarctic krill at levels similar to the old and the new EU allowable limits in fish feeds (150 and 350 mg kg?1) would induce kidney lesions in freshwater‐reared Atlantic salmon (Salmo salar). In addition to the diets containing krill, two high‐sodium fluoride (NaF) diets (1500 and 3500 mg kg?1) were used to investigate the effect on growth, feed intake, faecal excretion of minerals and accumulation of fluoride in various tissues. No major effects on growth or feed intake were observed. A higher proportion of the ingested fluoride was absorbed in salmon fed with the NaF diets compared with fish fed with krill shell diets. Fluoride accumulated in liver, kidney and especially bone. Faecal excretion of calcium and magnesium was higher for the NaF‐fed fish compared with fish fed with the control and krill shell diets, whereas the levels of these minerals in plasma were unaffected. Dietary fluoride from krill shells did not induce kidney lesions. One‐third of the salmon fed with the highest NaF diet showed signs of crystal formation within the distal tubules and/or collecting ducts in the kidney.  相似文献   

6.
A growth study was conducted to determine the dietary niacin requirement of the Indian catfish, Heteropneustes fossilis (Bloch), fingerlings (Mean weight 9.41 ± 0.18 g). Semi‐purified diets with five levels (0, 5, 10, 20 and 40 mg kg?1 diet) of supplemental niacin were fed to H. fossilis for 15 weeks. Each diet was fed to three replicate groups of fish. Results indicated that the highest (P < 0.05) weight gain was for the fish fed the diet supplemented with 20 mg niacin kg?1, followed by fish fed the diets with 40, 10 and 5 mg niacin kg?1, and the lowest in fish fed the unsupplemented control diet. Patterns of specific growth rate (SGR) and protein efficiency ratio (PER) were similar to those of the weight gain. Survival of fish fed the control diet and niacin‐supplemented diet was 58% and 91–100% respectively. Niacin deficiency signs such as anaemia, anorexia, lethargy and skin haemorrhage were observed in fish fed the control diet. The haematocrit values (Ht) were higher (P < 0.05) in fish fed the diets supplemented with niacin than in fish fed the control diet. The hepatosomatic indexes (HSI) of fish fed with or without niacin‐supplemented diets were not significantly (P > 0.05) different from each other. Both body protein and lipid content were higher (P < 0.05) in fish fed the diet supplemented with 20 and 40 mg niacin kg?1, respectively, than those fish fed other diets. The niacin content in liver significantly (P < 0.05) reflected the supplementation level in the diet and ranged from 29.11 to 40.31 mg g?1 tissue. The associated liver niacin content for growth was about 47 μg g?1 tissue. Quadratic regression analysis showed that the dietary niacin requirement for maximal growth of H. fossilis under these experimental conditions was about 25 mg kg?1 diet.  相似文献   

7.
A 14‐week trial was conducted to investigate the effects of antinutritional factors (ANFs) commonly present in soybean ingredients, singly and in combination, on Atlantic salmon (Salmo salar L.) fed from start‐feeding. The experimental diets consisted of a negative control fish meal diet (FM), and a positive control diet with 167 g kg?1 soybean meal inclusion (SBM) and four diets based on the FM diet supplemented with 2 g kg?1 soya‐saponins (SAP), 1.5 g kg?1 isoflavones (IFL), 0.3 g kg?1 phytosterols (PHS) or a mixture of these (MIX). Fish fed the SAP diet showed significantly higher growth performance than those fed FM, while the IFL treatment significantly decreased growth performance of salmon fry. Fish fed the IFL diet had significantly lower maltase activity and higher trypsin activity in proximal intestine than fish fed the FM diet. Histological differences were observed in the liver of fish fed the IFL diet, characterized by reduced size of the hepatocytes. Fish fed the PHS and IFL diets showed the highest frequencies of skeletal deformities among the six treatments. In conclusion, the results indicate that purified isoflavones may negatively affect growth performance, intestinal function, liver metabolism and bone formation of salmon fry.  相似文献   

8.
Plasma and liver vitamin E concentrations in a population of farmed Atlantic salmon, Salmo salar L., fed commercial diets were measured by high-performance liquid chromatography. In healthy fish fed diets containing 160-210 mg kg?1all-racα-tocopheryl acetate, vitamin E accumulated in the liver and plasma. Over a 20-month period, beginning 4 months prior to seawater transfer, mean vitamin E concentrations ranged from 51 to 754 μg g?1 wet tissue in liver and from 7 to 68 μg mL?1 in plasma. In liver, a sharp increase in vitamin E concentrations was recorded between 6 and 10 weeks after transfer. In plasma a similar increase occurred between 4 and 5 months post transfer. Total lipid and polyunsaturated fatty acid concentrations were also measured in these tissues. Liver total lipid concentrations fell during the period of smoltification, but there was no relationship between vitamin E and either total lipid or total polyunsaturated fatty acid concentrations in liver or plasma.  相似文献   

9.
The present study was performed to assess to what degree supplemented dietary iodine (I) was retained in selected tissues, including the fillet of adult Atlantic salmon (Salmo salar) reared in sea water. Atlantic salmon weighing approximately 1.5 kg were randomly assigned to three net pens per treatment and fed moist pellets (based on minced saithe and herring) supplemented with 0, 40 or 80 mg iodine (as KI) kg?1 on dry weight basis for 150 days. The iodine concentrations in the experimental feeds were analysed to be 10, 54 and 86 mg kg?1 dry weight, respectively. Growth, mortality and blood haemoglobin concentration (Hb) were recorded. Iodine concentrations were measured in muscle, liver and kidney after 90 and 150 days of feeding by inductively coupled plasma‐mass spectrometry. In addition, plasma thyroxine (T4) and triiodo‐thyronine (T3) were determined. The weight gain during the period was approximately 1 kg for all treatments. There were no mortalities, and blood Hb levels were within normal ranges. The iodine concentration in muscle, liver and kidney were all affected by the dietary iodine level, despite wide intratreatment variation. After 150 days, fillets of fish fed 10, 54 and 86 mg I kg?1 showed mean concentrations of 0.4, 0.5 and 0.9 mg I kg?1 wet weight, respectively, whereas the iodine concentration in the liver and the kidney increased approximately three times in the dietary groups. Similarly, plasma T4 and T3 showed great variation within the treatments. No significant correlations were found between individual tissue iodine concentration and thyroid hormone concentration in any of the groups at any sampling time. This preliminary feeding experiment showed that fillet iodine in adult Atlantic salmon can be increased up to 1.4 mg I kg?1 wet weight by dietary iodine 80 times the minimum requirement for salmonids, without impacting health, performance or plasma thyroid hormone status.  相似文献   

10.
This study was undertaken to assess dorsal aorta cannulation as a method to evaluate alterations in diet composition and feeding protocol on pigment retention in salmonid fish. Temporal changes in blood astaxanthin concentrations of dorsal aortacannulated Atlantic salmon, Salmo salar L., were followed in relation to variations in dietary pigment concentration and fish-feeding husbandry protocol. The fish were held individually in 200-L fibreglass tanks supplied with running sea water. Each fish was forced to swim at 0.5 body lengths s?1 and was fed daily by hand to satiation. The fish had an average growth rate of 1% day?1. Blood astaxanthin concentrations were noted to be highly correlated (r= 0.995) with dietary levels of astaxanthin, but not as well correlated (r= 0.71) with total gut content of this pigment. Marked variations in blood astaxanthin concentration were noted between individual fish at each dietary pigment concentration, but the ranking of the fish was generally unaffected between each dietary pigment level. After cessation of feeding a diet supplemented with 75 mg of astaxanthin kg?1, salmon fed a diet with no pigment showed more-rapid blood pigment clearance than those that were starved. Likely, feed remaining in the alimentary tract of the starved fish functioned as a reservoir of pigment for the blood until the intestinal tract was empty. Blood pigment levels were not depressed in salmon fed a diet supplemented with 75 mg of astaxanthin kg?1 once daily instead of twice daily.  相似文献   

11.
An experiment was conducted to investigate the effect of dietary iron supplement on growth, haematology and microelements of juvenile grouper, Epinephelus coioides. Casein–gelatine‐based diets supplemented with 0, 50, 100, 150, 200 and 250 mg kg−1 iron from ferrous sulphate were fed to grouper (mean initial weight: 21.0 ± 0.2 g) for 8 weeks. Weight gain was highest in fish fed the diet supplemented with 100 mg kg−1 iron, intermediate in fish fed diets with 50, 150, 200 and 250 mg kg−1 iron and lowest in fish fed the basal diet. Feed efficiency followed a similar trend except that the lowest value was in fish fed the basal diet and the diet supplemented with 250 mg kg−1 iron. Hepatic iron was highest in fish fed diets supplemented with iron ≥100 mg kg−1, followed by fish fed diet with 50 mg kg−1 iron and lowest in fish fed the basal diet. The whole‐body iron was lowest in fish fed the basal diet but not significantly different from other groups, as judged by anova . Iron supplement to the basal diet had no significant effect on haematological parameters (red blood cell count, haematocrit and haemoglobin), hepatic copper concentration or manganese, zinc concentration in liver and whole body. Broken‐line analysis of hepatic iron indicated that iron supplementation of 100 mg kg−1 satisfied the hepatic iron storage and that further supplementation did not expand the iron status.  相似文献   

12.
Atlantic salmon, Salmo salar L., juveniles, with a mean initial weight of 1.75 g, were fed casein-based purified diets which had been supplemented with different levels of astaxanthin for a 10-week period. The astaxanthin content of the diets ranged from 0 to 190 mg kg?1 dry diet. The growth and survival of the juveniles were recorded throughout the experiment. The proximate composition, astaxanthin and vitamin A content were determined from whole-body samples at the start and termination of the experiment. The dietary treatment was found to affect growth significantly (P < 0.05). A reduction in the mean weight of the juveniles was observed in the groups fed the diets without astaxanthin supplementation. There was no difference in growth rate between the fish in the groups fed the diets containing 36 or 190 mg astaxanthin kg?1 dry diet, whereas the fish in the group fed the diet containing 5.3 mg astaxanthin kg?1 dry diet had a lower growth rate. There was a tendency to higher survival in the groups fed the diets containing astaxanthin when compared with the groups fed the non-supplemented diets. The moisture and ash contents were significantly lower and the lipid content was higher in the groups fed the astaxanthin-supplemented diets. The astaxanthin and the vitamin A concentrations in the fish were found to be dependent upon the dietary astaxanthin dose; the highest values were found in the fish fed the diet with the highest astaxanthin content. These results strongly indicate that astaxanthin functions as a provitamin A for juvenile Atlantic salmon. The body storage of vitamin A increased in the fish fed the diets containing astaxanthin. However, the increase was low in the fish fed the diet containing 5.3 mg astaxanthin kg?1 dry diet.  相似文献   

13.
Seven isonitrogenous and isoenergetic experimental diets were formulated to investigate the effect of low molecular weight fish protein hydrolysate (FPH) in diets on growth performance, feed utilization and liver IGF‐I mRNA levels in Japanese flounder (38.80 ± 1.11 g) fed with high plant protein diets. Fish meal protein was, respectively, replaced by 6% (FPH6), 11% (FPH11), 16% (FPH16), 21% (FPH21), 26% (FPH26) FPH of total dietary protein. FPH diets contained a constant high level of plant protein (690 g kg?1) from soybean meal. As a positive control diet, FM2 contained about 590 g kg?1 plant protein and 410 g kg?1 fish meal protein, while negative control diet FM1 contained about 690 g kg?1 plant protein and 310 g kg?1 fish meal protein. The expression levels of liver IGF‐I mRNA were evaluated using real‐time PCR normalized against the 18S rRNA gene. The results showed that moderate low molecular weight FPH (FPH11) improved growth performance and protein retention. Fish fed with FPH11 and control diet FM2 had similar growth and feed utilization, while high‐level low molecular weight FPH did not improve growth performance and protein retention, and depressed liver IGF‐I mRNA expression in Japanese flounder.  相似文献   

14.
Presmolt Atlantic salmon were fed a fish meal based experimental diet supplemented with graded levels of ascorbate-2-monophosphate (AP), equivalent to 40, 400, 2000 and 4000 mg ascorbic acid (AA)/kg for 6 months prior to a bacterial challenge experiment. The liver AA concentration reflected the dietary intake of AP, but not linearly. Growth, hematology and acid phosphatase activity in zymosan stimulated macrophages were not affected by dietary AP. Serum hemolytic complement activity was higher in fish fed the highest AP level, but the variation was not significant. Production of specific antibodies was significantly higher in fish fed the highest AP level 11 and 17 weeks after vaccination. Bacterial challenge with Aeromonas salmonicida showed increased survival in the 4000 AP group. Lysozyme activity in headkidney and serum complement activity and serum iron in fish surviving the challenge were higher in the 4000 AP group, indicating important roles of vitamin C on lysozyme, complement and iron in non-specific disease resistance. The results indicate that high dietary levels of AP favourably affect health in Atlantic salmon. Disease resistance was, however, not correlated with the AA status in the liver.  相似文献   

15.
Sterile triploid fish are increasingly being used in salmon aquaculture and fisheries. For production, welfare, and experimental reasons, it is important to understand the efficacy of anesthetics and the physiological response to anesthesia in triploid fish. The efficacy (time to anesthesia and recovery) of 30, 40, 50, and 80 mg Finquel® (MS 222) L?1 and 12.5, 20, and 30 mg (active ingredient) Aqui-S® (isoeugenol) L?1 and the acute hematocrit and plasma (cortisol, glucose, osmolality, lactate) response to 30, 50, and 80 mg Finquel® L?1 and 12.5 mg Aqui-S® L?1 was therefore measured in diploid and triploid post-smolt Atlantic salmon, Salmo salar. Ploidy had no effect on the efficacy of Finquel® or Aqui-S®. Although triploidy had significant transient effects on all physiological parameters measured following anesthesia, the differences were small and likely biologically negligible with respect to the ability of Atlantic salmon to recover from the range of anesthetics tested.  相似文献   

16.
The aim of the present study was to investigate the retention of menadione nicotinamide bisulphite (MNB; vitamin K3) and phylloquinone (vitamin K1) in Atlantic salmon (Salmo salar L.). Another objective was to find a reliable method for determination of menadione in fish feed, and to include and validate more matrices in the methods for phylloquinone and menaquinones (vitamin K2). Duplicate tanks of Atlantic salmon (～93 g) were fed four levels (0–1000 mg menadione kg?1 feed) of MNB for 9 weeks. The concentration of menadione and phylloquinone in the feed and the concentration of phylloquinone and menaquinone‐4 (MK‐4) in the tissues were determined. The analysed concentration of dietary menadione found in feed indicated a substantial loss of MNB during feed production. This assumption was supported by screening 15 commercial fish feed samples which also revealed menadione concentrations far below the recommended level. MNB fed salmon showed only a minor increase in liver MK‐4 concentration, compared to salmon fed phylloquinone which had a considerably higher level of liver phylloquinone, indicating a higher retention of phylloquinone compared to menadione in Atlantic salmon. Due to highly varying stability and bioavailability of the different vitamin K derivatives, vitamin K supplementation in fish feed needs a revision.  相似文献   

17.
Maximum limits of organic and inorganic mercury in fish feed   总被引：1，自引：0，他引：1  
The relatively high levels of mercury found in fish feeds might form a fish health and food safety risk. The present study aims to establish sublethal toxic threshold levels in fish and assess feed‐fillet transfer of dietary mercury. Atlantic salmon (Salmo salar L.) parr were fed for 4 months on fish meal‐based diets supplemented with mercuric chloride (0, 0.1, 1, 10 or 100 mg Hg kg?1 dry weight (DW)) or methylmercuric chloride (0, 0.1, 0.5, 5 or 10 mg MeHg kg?1 DW). At the end of the experiment, dietary inorganic mercury mainly accumulated in intestine (80% of body burden) and assimilation was low (6%). In contrast, methylmercury readily accumulated in internal organs and muscle (80% of body burden) and had a relatively high assimilation (23%). Highest accumulation of dietary inorganic mercury was observed in the gut and kidney. Fish fed 10 mg Hg kg?1 had an early (after 2 months) significant increase in renal metallothionein (MT) level and intestinal cell proliferation, followed by intestinal pathological conditions after 4 months of exposure. At 100 mg Hg kg?1, intestinal and renal function were reduced as seen from the significantly reduced protein and glycogen digestibility and increased plasma creatinine levels. For dietary methylmercury (MeHg), highest accumulation was found in blood and muscle. Intestinal cell proliferation and liver MT significantly increased at 5 mg MeHg kg?1 after 2 months of exposure. At the end of the experiment, blood haematology was significantly affected in fish fed 5 mg MeHg kg?1 and these fish exceeded the current food safety limit for mercury. Tissue MT induction and intestinal cell proliferation appeared to be useful and quantifiable early indicators of toxic mercury exposures. Based on the absence of induction of these early biological markers such as MT and cell proliferation, nonobserved effect levels (NOELs) could be set to 0.5 mg Hg kg?1 for dietary methylmercury and 1 mg Hg kg?1 for inorganic mercury. Lowest observed effect levels (LOELs) levels could be set to 5 mg kg?1 for methylmercury and 10 mg Hg kg?1 for inorganic mercury.  相似文献   

18.
The rate of deposition of carotenoids in pen-reared coho salmon was investigated by the addition of known carotenoid levels to diets. The carotenoids added to the diets were derived from red crab (P. planipes), and a process is described for the preparation of a soya oil carotenoid concentrate. Using a 3-stage counter-current extraction process, extracts containing 155 mg/100 g oil were prepared from red crab (P. planipes). Oregon moist pellets containing 3, 6, and 9 mg carotenoid/100 g were prepared using these extracts and were fed to coho salmon (Oncorhynchus kisutch) for 120 days. The amount of carotenoid deposited in the flesh of the fish was related to the carotenoid content of the diet and to the weight of the fish. Fish fed diets containing 6 and 9 mg carotenoid/100 g for the same length of time contained 60% more flesh carotenoids than those fed 3 mg/100 g. In general, after 120 days of feeding, only those fish feeding on diets containing 6.0 and 9.0 mg carotenoid/100 g and weighing over 215 g were assessed as having good-to-excellent coloration. Analysis of the flesh showed that there was no correlation between its carotenoid and fat contents.  相似文献   

19.
An 8‐week feeding trial was conducted to establish the dietary vitamin E requirement of juvenile cobia. The basal diet was supplemented with 10, 20, 30, 40, 60, 120 mg vitamin E kg?1 as all‐rac‐α‐tocopheryl acetate. The results indicated that fish fed the diets supplemented vitamin E had significantly higher specific growth rate, protein efficiency ratio, feed efficiency and survival rate than those fed the basal diet. It was further observed that vitamin E concentrations in liver increased significantly when the dietary vitamin E level increased from 13.2 to 124 mg kg?1. Fish fed the basal diet had significantly higher thiobarbituric acid‐reactive substances concentrations in liver than those fed the diets supplemented vitamin E. Fish fed the diets supplemented with 45.7 and 61.2 mg kg?1 vitamin E had significantly higher red blood cell and haemoglobin than those fed the basal diet, while fish fed the diets supplemented with 61.2 and 124 mg kg?1 vitamin E had higher immunoglobulin concentration than those fish fed the basal diet. Lysozyme and superoxide dismutase were significantly influenced by the dietary vitamin E level. The dietary vitamin E requirement of juvenile cobia was established based on second‐order polynomial regression of weight gain and lysozyme to be 78 or 111 mg all‐rac‐α‐tocopheryl acetate kg?1 diet, respectively.  相似文献   

20.
Transferrin (Tf) plays an important function in iron homeostasis and metabolism of organisms. In this study, we identified and characterized the Tf gene in Megalobrama amblycephala and evaluated its expression in basal conditions as well as after iron overload and experimental infection with Aeromonas hydrophila. Furthermore, we studied the iron binding properties of recombinant Tf. The full-length M. amblycephala Tf complementary DNA (cDNA) (GenBank accession no.: KX698308) of 2245 bp was cloned and contained a 1953 bp open reading frame (ORF) encoding 650 amino acid residues and flanked by a 68 bp 5′ and a 204 bp 3′ untranslated regions (UTR). Predicted conservative structure illustrated that M. amblycephala Tf consisted of two conservative Tf domains. Amino acid sequence alignment revealed that M. amblycephala Tf had high similarity with that of cyprinids deposited in Genbank, and phylogenetic analysis showed that M. amblycephala Tf clustered with Ctenopharyngodon idella and Hypophthalmichthys molitrix. Tissue expression pattern analyses demonstrated that the liver was the main Tf mRNA expressing organ, being significantly higher than other tissues (p < 0.05). In the liver, Tf mRNA expression in fish artificially injected with the pathogenic bacteria A. hydrophila was significantly upregulated, reaching a peak at 12 h post injection (hpi) and then decreasing afterward. The expression in FeCl3-injected fish showed a similar tendency, but reached a peak at 8 hpi. Meanwhile, fish serum iron significantly decreased following A. hydrophila injection, but increased to peak at 4 hpi and then decreased in FeCl3-injected fish. The recombinant M. amblycephala Tf showed iron binding capacity using CAS analysis. These results are helpful to understand the structure and regulation of expression of Tf, as well as the specific function of Tf for both immune responses and iron homeostasis.  相似文献   

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