Molecular cloning and sequencing of hemoglobin-β gene of channel catfish, Ictalurus punctatus Rafinesque

The hemoglobin-β gene of channel catfish, Ictalurus punctatus, was cloned and sequenced. Total RNA from head kidneys was isolated, reverse transcribed and amplified. The sequence of the channel catfish hemoglobin-β gene consists of 600 nucleotides. Analysis of the nucleotide sequence reveals one open reading frame and 5′- as well as 3′-untranslated regions. The open reading frame of the sequence potentially encodes 148 amino acids with a calculated molecular mass of 16.3 kDa. The pI and charge at pH 7.0 of the deduced hemoglobin-β protein were 7.28 and 0.47, respectively. Overall, 22 amino acid residues were conserved throughout the sequences, including His64 and His93, the sites for heme-binding. Unlike the counterpart of other common cultured fish such as Salmo salar, Oncorhynchus nerka, Oncorhynchus mykiss, Cyprinus carpio and Ctenopharyngodon idella, the hemoglobin-β of channel catfish did not have cysteine. The amino acid sequence of channel catfish hemoglobin-β shows 84% homology with that of Silurus asotus (both are in the order Siluriformes). However, comparison with those of other fish species shows homology ranging from 53 to 68%. Structural analysis by the 3D-PSSM program displays that channel catfish hemoglobin-β has eight α-helices, A–H.     

Cloning,characterization and expression of the pepsinogen C from the golden mandarin fish <Emphasis Type="Italic">Siniperca scherzeri</Emphasis> (Teleostei: Perciformes)

Pepsinogens are precursors of pepsins, which are gastric digestive proteinases that degrade food proteins into peptides. In the study reported here, the cDNA and its corresponding genomic DNA of the golden mandarin fish (Siniperca scherzeri, Perciformes) pepsinogen C (PGC) were cloned and sequenced. The golden mandarin fish PGC gene was deduced to have nine exons and eight introns, a structure similar to the PGCs of other vertebrates. The full-length cDNA was found to contain a 37-bp 5′-untranslated region, a 1,164-bp open reading frame, and a 304-bp 3′-untranslated region and the PGC protein to consist of a signal peptide, an activation segment, and a pepsin moiety. A sequence analysis revealed that pairwise sequence similarities of PGC proteins are around 70% between golden mandarin fish and other vertebrate groups, and around 90% within the fish group. A comparison of vertebrate PGC protein sequences revealed two motifs. One was in the activation segment that occurred only in the mammal and avian PGCs, suggesting that PGCs active in homeotherms (mammal and avian) have different activation mechanisms than those in poikilotherms (amphibian and fish). The second was in the pepsin moiety that occurred only in fish, suggesting the primitive position of fish among vertebrates. PGC mRNA is mainly expressed in the stomach and esophagus and at much lower levels in the skin and muscle. Taken together with results reported from other studies, the results reported here will lead to a better understanding of the molecular mechanisms of fish digestive physiology and the evolution of fish pepsinogen genes.     

Population characteristics of channel catfish near the northern edge of their distribution: implications for management

Channel catfish, Ictalurus punctatus (Rafinesque), populations in six lakes in northern Idaho, USA, were sampled to describe their population characteristics. During the summers of 2011 and 2012, 4864 channel catfish were sampled. Channel catfish populations had low to moderate catch rates, and length structure was dominated by fish <400 mm. Channel catfish were in good body condition. All populations were maintained by stocking age‐1 or age‐2 fish. Growth of fish reared in thermally enriched environments prior to stocking was fast compared to other North American channel catfish populations. After stocking, growth of channel catfish declined rapidly. Once stocked, cold water temperatures, prey resources and (or) genetic capabilities limited growth. Total annual mortality of age 2 and older channel catfish was generally <40%. Tag returns indicated that angler exploitation was low, varying from 0 to 43% among lakes. This research provides insight on factors regulating channel catfish population dynamics and highlights important considerations associated with their ecology and management.     

斑点叉尾鮰病毒囊膜蛋白ORF6在昆虫细胞中的表达

为构建基于杆状病毒表达系统的CCV新型亚单位疫苗,将CCV的囊膜蛋白基因ORF6克隆至杆状病毒转座载体pFastBacTM 1质粒中,并将阳性重组转座质粒转化进含穿梭载体Bacmid的感受态细胞DH10Bac中,获得重组子rBacmid-ORF6。在脂质体介导下将该重组子转染sf9昆虫细胞,获得重组杆状病毒AC-ORF6。AC-ORF6感染的sf9昆虫细胞,经超薄切片电镜观察,可见重组杆状病毒呈多粒包埋,经间接免疫荧光、Western-blotting检测,CCV的ORF6蛋白可以在感染了AC-ORF6的sf9细胞中表达。研究表明,获得了插入ORF6基因的重组杆状病毒,并且该基因可以在重组杆状病毒介导下在昆虫细胞中表达,从而为基于CCV ORF6的杆状病毒亚单位疫苗研究奠定了基础。     

Effects of Varying Levels of High‐Protein Distiller's Grains on Growth Performance of Channel Catfish,Ictalurus punctatus,and Post‐Extrusion Feed Pellet Characteristics

Channel catfish, Ictalurus punctatus, remains the USA's largest aquaculture industry. However, in recent years, high feed prices have negatively impacted profitability. Production of ethanol as a biofuel has increased dramatically. Companies have modified their processes to enhance ethanol yield and these modified processes also increase the crude protein content of the byproduct. The object of this study was to evaluate this high‐protein dried distiller's grains (HP‐DDG) for its suitability in catfish diets. A total of 25 full‐sibling channel catfish (7.1 ± 2.3 g) were randomly stocked into each of twelve 260‐L polyethylene tanks to achieve 25 fish per tank. The control diet was similar to a commercial formulation. Experimental diets contained 20, 40, or 40% HP‐DDG with added lysine (1% of total diet). There were three replicate tanks per diet. Fish were fed to apparent satiation twice daily for 9 wk. Average harvest weights for fish fed the 40% HP‐DDG diet without lysine supplementation (57.0 g) were significantly smaller than that for fish fed the control diet (77.7 g). Average harvest weights of fish fed 20% HP‐DDG (86.8 g) were significantly greater than that of fish fed either 40% HP‐DDG (57.0 g) or 40% HP‐DDG + lysine (73.7 g). There were no significant differences in feed conversion ratios or survivals among treatments, which overall averaged 1.1 and 99%, respectively. These data indicate that HP‐DDG appears to be a suitable ingredient in channel catfish diets up to at least 20% of the total formulation. Data also indicate that inclusion levels of at least 40% HP‐DDG are likely limiting in lysine.     

The Effects of Water Velocity on the Growth,Dressout, and Body Composition of Channel Catfish,Ictalurus punctatus,Raised in Cicular Tanks

Research was conducted to determine the influence of water velocity on growth, dressout characteristics and fillet proximate composition of channel catfish, Ictalurus punctatus, raised in circular tanks. In this study, channel catfish cultured in water velocities of 4 cm/second averaged 75 g/fish higher weight gain and 0.12%/day greater specific growth rates than channel catfish cultured in tanks having no water velocity (P < 0.05). Channel catfish cultured at water velocities of 4 cm/second had significantly higher (P < 0.05) feed conversion efficiency and condition factor than channel catfish cultured in tanks having no water velocity. Channel catfish cultured at water velocities of 4 cm/second had significantly higher (P < 0.05) percentage carcass weight, fillet weight, and fillet moisture. The percentage visceral and fillet fat of channel catfish cultured at 4 cm/second was significantly lower (P < 0.05) than that for channel catfish raised in tanks having no water velocity. These results indicate that when cultured from initial weights of approximately 100 g to final weights exceeding 454 g in an environment having a water velocity of 4 cm/second, channel catfish have greater growth, dressout and lower fat levels than channel catfish produced in tanks having the identical water exchange rates but no water velocity.     

Effects of Feeding Diets Containing 34 or 38% Protein at Two Feeding Frequencies on Growth and Body Composition of Channel Catfish

Channel catfish, Ictalurus punctatus, fingerlings were stocked (13,585 fish/ha) in twelve 0.04-ha earthen ponds and fed to satiation with diets containing either 34 or 38% protein (79.1 or 88.8 mg protein/kcal), either once or twice daily for 170 days. Experimental diets with the proper levels of essential amino acids, vitamins, and minerals were formulated by a commercial feed mill. No significant differences (P < 0.05) in growth and body composition of channel catfish were found when analyzed by protein level, feeding frequency, or their interaction. Average individual fish weight at harvest was 461 g. Net production was 4,152 kg/ha. Percentage protein, fat, and ash in the waste (head, skin, viscera, and frame) were 41.5, 41.4, and 12.2%, respectively, while fillet had 65.7, 30.4, and 4.0%, respectively.     

Digestibility of Alternative Protein‐Rich Feedstuffs for Channel Catfish,Ictalurus punctatus

Apparent digestibility coefficients (ADCs) of amino acids, crude protein, gross energy, and dry matter of canola meal, corn gluten feed, fish offal meal, shrimp and fish offal meal, poultry by‐product meal, and hydrolyzed feather meal were determined for channel catfish, Ictalurus punctatus. Experimental diets contained 30% test ingredient, 69.5% casein‐based reference diet, and 0.5% chromic oxide. Groups of 20 fish (102.45 g) were fed the experimental diets twice a day at 3.5% body weight. Fecal samples were collected in triplicate daily at 0000 h and 0600 h after settlement into collection devices. Shrimp and fish offal meal and corn gluten feed presented significantly lower (P < 0.05) ADC for dry matter (59.5 and 39.3%) suggesting their low value as feedstuffs for catfish feeds. Although ADC values for crude protein were above 80% for all the test ingredients, amino acid digestibility varied significantly, except for histidine whose ADC remained constant regardless of the protein source. Lysine was the first limiting amino acid in most of the test ingredients, except in fish offal meal and poultry by‐product meal. Among the protein sources tested, only fish offal meal and poultry by‐product meal met channel catfish amino acid requirements for a 28% digestible protein grow‐out diet.     

Effects of Protein Level and Feeding Frequency on Growth and on Body Composition of Third-Year Channel Catfish Cultured in Ponds

Channel catfish, Ictalurus punctatus, adults were stocked at 3,705 fish/ha in twelve 0.04-ha earthen ponds and fed to satiation either once or twice daily with diets containing either 32 or 38% protein for 170 days. Experimental diets with the appropriate levels of essential amino acids, vitamins, and minerals were formulated by a commercial feed mill. There were no significant differences (P > 0.05) in growth and body composition of channel catfish when analyzed by protein level, feeding frequency, or their interaction. Average individual fish weight at harvest was 1,600 g. Average net production was 3,125 kg/ha. Dry-weight percentages of protein, fat, and ash in the carcass were 55.5, 38.1, and 6.7%, respectively, and in the waste (head, skin, and viscera) were 40.5, 43.2. and 12.5%. respectively. Third-year channel catfish may be able to utilize a diet with lower (<32%) protein levels and a reduced energy: protein ratio.     

POLYCULTURE OF CHANNEL CATFISH (Ictalurus punctatus) WITH ALL-MALE TILAPIA HYBRID

Channel catfish (Ictalurus punctatus) (x? = 0.8 g) and all-male hybrid tilapia fingerlings (Sarotherodon mossambica ♂ × S. hornorum ♀) (x? = 35.0 g) were stocked in 0.04 ha replicated ponds in Baton Rouge, Louisiana, in March and July 1981, respectively. The ponds were stocked at densities of 11,110 catfish per ha, 11,110 catfish with 5,550 tilapia per ha, 7,400 catfish per ha, and 7,400 catfish with 3,700 tilapia per ha. The fish were fed daily at 4% of estimated catfish biomass and were harvested in November 1981. There were no differences in dissolved oxygen or water temperature among the four culture systems (P > 0.05). The presence of tilapia, however, significantly increased water turbidity, pH and chlorophyll a concentrations (P < 0.05). Tilapia did not improve water quality and may have deteriorated it. Tilapia did not affect channel catfish growth or production (P > 0.05), but the presence of tilapia did significantly increase total fish yield (P < 0.05) by 13.5 and 32.2% at low and high catfish densities, respectively. Channel catfish and tilapia averaged 390 and 245 g at harvest, respectively. Overall catfish survival averaged 61%. Tilapia survival was 72% and 61% at low and high densities, respectively.     

Evaluation of Cuphea Meal as an Ingredient Replacement in Channel Catfish,Ictalurus punctatus,Diets

ABSTRACT

Cuphea meal is a new, alternative feedstuff that has potential as a sustainable, economical replacement for wheat, rice, and corn ingredients in channel catfish, Ictalurus punctatus, diets. Channel catfish fingerlings were fed a control diet containing wheat or two experimental diets containing 7.5% cuphea meal, or 12.5% cuphea meal for eight weeks to determine if cuphea meal could replace wheat products in catfish diets. Mean (±SE) weight gains were 317.8 ± 28.8 g, 407.0 ± 36.9 g, and 372.8 ± 29.8 g for fish fed the control diet, the 7.5% cuphea meal diet, and the 15% cuphea meal diet, respectively, and there were no significant differences (P < 0.05) among treatments. Mean (±SE) whole-body protein of fish fed the cuphea diets (13.3 ± 0.66 and 14.5 ± 0.21%) was significantly (P < 0.05) higher than that of fish fed the wheat diet (12.7 ± 0.44%). Cuphea meal enhanced body composition of juvenile channel catfish without affecting growth or survival. Therefore, cuphea meal is a promising candidate for replacement of wheat bran at the levels tested.     

Growth, feed conversion, fillet proximate composition and resistance to Edwardsiella ictaluri of channel catfish, Ictalurus punctatus (Rafinesque), blue catfish, Ictalurus furcatus (Lesueur), and their reciprocal F1 hybrids fed 25% and 45% protein diets

Juvenile channel catfish, Ictalurus punctatus (Rafinesque), blue catfish, I. furcatus (Lesueur), and their reciprocal Fl hybrids were fed practical diets containing 25% and 45% protein during a 10-week trial to determine the effects of genotype, dietary protein level and genotype X diet interactions on growth, feed conversion ratio (FCR), fillet proximate composition and resistance to the bacterium Edwardsiella ictaluri. Rankings of genotypes (best to worst) for absolute weight gain, percentage weight gain and FCR were: channel, channel female X blue male, blue, and blue female X channel male for the 25% protein diet; and channel, channel X blue, blue X channel, and blue for the 45% diet. Diet did not affect growth or FCR of channel catfish, but growth and FCR were better for blue catfish and both hybrids fed the 25% diet compared to those fed the 45% diet. Channel catfish additive genetic and maternal effects were favourable, and heterosis was negative for growth and FCR. After adjusting for effects of fish size, genotype had no effect on fillet composition. Fillet protein was higher for all genotypes, and fillet lipid was lower for blue catfish and hybrids fed the 45% diet than for fish fed the 25% diet. Genotype X diet interactions observed for growth, FCR and fillet lipid appeared to be a result of poor palatability of the 45% diet to blue catfish and hybrids. Survival (76-93%) and antibody levels (0.10-0.24 OD) after exposure to E. ictaluri at the end of the feeding trial were not affected by genotype or diet. Hybridization of blue catfish and channel catfish would not be an effective method for improving the traits measured for the fish strains and diets used in this study.     

Assessment of a channel catfish population in a large open river system

Estimates of dynamic rate functions for riverine channel catfish, Ictalurus punctatus (Rafinesque), populations are limited. The open nature and inherent difficulty in sampling riverine environments and the propensity for dispersal of channel catfish impede estimation of population variables. However, contemporary population models (i.e. robust design models) can incorporate the open nature of these systems. The purpose of this study was to determine channel catfish population abundance, survival and size structure and to characterise growth in the lower Platte River, Nebraska, USA. Annual survival estimates of adult channel catfish were 13%–49%, and channel catfish abundance estimates ranged from 8,281 to 24,261 fish within a 10‐km sampling reach. Channel catfish were predominantly (90%) <age 5 and <400 mm total length, and adult growth was similar to other populations across the species’ range. The channel catfish population characteristics in the lower Platte River are likely a result of a combination of factors including recreational harvest and potential shifts in habitat during different life stages. A multifaceted sampling and analytical approach provided additional information such as movement and abundance estimates and may also help to decipher abiotic and biotic factors that interact when managing fish populations in riverine environments.     

Production Characteristics of Channel Catfish,Ictalurus punctatusStocked at Two Densities in the Partitioned Aquaculture System

Abstract

This study was conducted to determine if channel catfish could be cultured at an increased density in the Partitioned Aquaculture System (PAS) without significantly affecting performance. Channel catfish fingerlings (36.53±6.76 g; mean ±SD) were initially stocked into six 9.15 m³ sections at 3,461±317 fish per section, twice the designed carrying capacity, and fed twice daily to satiation. After 75 days, the density of three units was reduced by approximately 50% and all six units were fed for another 97 days. There was no significant difference (P > 0.05) in mean growth rate, feed conversion ratio, or production between fish grown at the low- and high-density treatments. Also, length variation (CV) and condition factors (K) were similar (P > 0.05) between fish grown at the low and high-density. Increasing density by twice the designed carrying capacity did not affect performance of channel catfish in the PAS.