Gastrointestinal torsion in a channel catfish (Ictalurus punctatus)

A case of gastrointestinal torsion with dilatation in a farm-raised channel catfish (Ictalurus punctatus) was examined at the Thad Cochran National Warmwater Aquaculture Center (Stoneville, Mississippi, USA). The affected fish was a gravid female broodfish, which displayed pale gills and a markedly distended abdomen. Internal examination revealed that the gastrointestinal tract and ovaries were rotated around each other four times in a counterclockwise direction as viewed in right lateral recumbency. The catfish had a markedly distended gastrointestinal tract, pale liver, hypoplastic spleen, hypoplastic swim bladder, and high volume of ascitic fluid. Blood analysis indicated multiple abnormalities, including severe anemia and metabolic acidosis. The etiology of the torsion was uncertain; however, the presence of a hypoplastic swim bladder most likely allowed for increased movement of the gastrointestinal tract and ovaries. When examining cases of abdominal distention in fish, gastrointestinal torsion can be considered among the differential diagnoses.     

Identification and expression analyses of poly [I:C]-stimulated genes in channel catfish (Ictalurus punctatus)

Channel catfish (Ictalurus punctatus) have proven to be an excellent model with which to study immune responses of lower vertebrates. Identification of anti-viral antibodies and cytotoxic cells, as well as both type I and II interferon (IFN), demonstrates that catfish likely mount a vigorous anti-viral immune response. In this report, we focus on other elements of the anti-viral response, and identify more than two dozen genes that are induced following treatment of catfish cells with poly [I:C]. We showed that poly [I:C] induced type I interferon within 2 h of treatment, and that characteristic interferon stimulated genes (ISGs) appeared 6–12 h after exposure. Among the ISGs detected by RT-PCR assay were homologs of ISG15, Mx1, IFN regulatory factor 1 (IRF-1), inhibitor of apoptosis protein-1 (IAP-1) and the chemokine CXCL10. Microarray analyses showed that 13 and 24 cellular genes, respectively, were upregulated in poly [I:C]-treated B cell and fibroblast cultures. Although many of these genes were novel and did not fit the profile of mammalian ISGs, there were several (ISG-15, ubiquitin-conjugating enzyme E2G1, integrin-linked kinase, and clathrin-associated protein 47) that were identified as ISGs in mammalian systems. Taken together, these results suggest that dsRNA, either directly or through the prior induction of IFN, upregulates catfish gene products that function individually and/or collectively to inhibit virus replication.     

Growth under stressed conditions in juvenile channel catfish Ictalurus punctatus (Rafinesque) as measured by nucleic acids

• 1.1. Juvenile channel catfish exposed to stressed conditions (low oxygen and a bacterial infection) showed a decrease in body condition during a 20-day experiment. There was no change in length or condition for control fish, but weight decreased.
• 2.2. RNA concentration and RNA:DNA ratios were higher in control fish when initial length or initial weight were removed statistically. Protein:DNA ratios were also higher in control fish.
• 3.3. Regression analysis indicated that RNA:DNA ratios were better predictors of final standard length and final wet weight than RNA concentration alone for the stressed conditions, but not the control condition.

     

Histology of cultured channel catfish, Ictalurus punctatus (Rafinesque)

Dissolved oxygen and un-ionized ammonia concentrations were monitored in 12 0.04 ha earthen ponds stocked with 10 000 channel catfish, Ictalurus punctatus ,/ha. Gill, liver and trunk kidney tissue samples were removed periodically for histological examination. Total ammonia and dissolved oxygen levels were in the ranges reported for catfish culture at this level of intensity. Average un-ionized ammonia nitrogen concentrations ranged from 20 to 67 μgh⁻¹ and average daily maxima ranged from 63 to 183 μgh⁻¹. Gill lesions characteristic of un-ionized ammonia exposure were common in fish from all ponds.     

Ultrastructure of the liver in channel catfish Ictalurus punctatus (Rafinesque)

Livers of 38 channel catfish were studied by light and electron microscopy and the morphology of hepatocytes, endothelial cells, Kupffer cells, fat-storing cells, macrophages, exocrine pancreatic cells, and epithelium of bile pre-ductules and ducts was described, Hepatocytes contained large peri-canalicular bodies which showed acid hydrolase activity. A comparison between catfish liver and that of other teleosts was made. The applicability of the findings to pathobiological studies of teleost liver is described.     

Immune hypersensitivity in the channel catfish, Ictalurus punctatus (Rafinesque)

Channel catfish, Ictalurus punctatus , exhibited passive cutaneous anaphylaxis (PCA) when sensitized with Flexibacter columnaris antiserum produced in channel catfish (the first record of PCA in any fish), but not when sensitized with homologous antiserum against channel catfish virus. Channel catfish did not give delayed skin hypersensitivity responses after immunization with either channel catfish virus or F. columnaris .     

Cortisol-induced hematologic and immunologic changes in channel catfish (Ictalurus punctatus)

1. Intravenous injections of physiologic doses of cortisol resulted in both hematologic and immunologic changes in channel catfish peripheral blood leucocytes. These changes mimicked those seen when catfish were acutely stressed by handling and transport. 2. Eighteen hours after the administration of cortisol, decreases in the number of circulating lymphocytes and concomitant increases in the number of circulating neutrophils were observed, i.e. to the same levels seen previously in stressed fish. 3. Functional analysis of peripheral blood leucocytes from cortisol-injected fish indicated that the remaining lymphocytes were no longer capable of responding to mitogenic stimuli. 4. This suppression of mitogenic stimuli was not seen when peripheral blood leucocytes were cultured in vitro with physiologic doses of cortisol. 5. This latter observation suggests that the cortisol alone was probably not directly responsible for the loss of responsiveness but possibly acted in vivo as an initiator of other events that eventually resulted in the observed immunosuppression.     

Comparative study of mannose-binding C-type lectin isolated from channel catfish (Ictalurus punctatus) and blue catfish (Ictalurus furcatus)

Mannose-binding C-type lectin (MBL) was isolated from channel catfish (Ictalurus punctatus) NWAC 102 and 103 strains, blue catfish (Ictalurus furcatus) D+B and Rio Grande strains, hybrid catfish (channel catfish female NWAC 103 x blue catfish male D+B) sera, and purified by affinity chromatography from channel catfish Norris strain serum. Reduction of purified channel catfish MBL with 2-ME yielded a single band of 62 kDa by SDS-PAGE and Western blot analysis using guinea pig anti-MBL IgG as primary antibody. Channel catfish NWAC 102 strain, channel catfish NWAC 103 strain and hybrid catfish sera had molecular masses of 63 kDa for MBL. Blue catfish (D+B strain) serum MBL had a molecular mass of 66 kDa. Rio Grande blue catfish serum MBL had a molecular mass of 65 kDa. Amino acid composition analysis (mol%) of the affinity-purified channel catfish MBL found a high content of serine present. Functional binding studies of channel catfish and blue catfish MBLs binding to Edwardsiella ictaluri were done using a dot-immunoblot ELISA method. A dot-immunoblot ELISA binding assay was done to compare nine different strains and species of channel catfish and blue catfish for their levels of serum MBL. Blue catfish had higher levels of MBL than did the various strains of channel catfish tested. MBL could be used as a genetic marker for selection of disease resistance in the different strains of catfish used in aquaculture. This study describes the presence of serum MBL in catfish and evidence for a C-type lectin complement pathway of innate immunity.     

Definition of the USDA103 strain of channel catfish (Ictalurus punctatus)

Although there are differences in performance between genetic groups of channel catfish, identification and management of these groups is difficult because catfish strains look alike and individuals cannot be tagged efficiently. Thus, US catfish producers have not been able to objectively identify fish from different strains or populations, and it has been difficult for them to maintain the genetic purity of populations on the farm. We have developed a multiplexed microsatellite genotyping system to define catfish populations based on allelic frequency and exclusion. A commercial catfish genotype database was developed using catfish samples collected from 24 processing plants in the four main US catfish-producing states. The utility of the system was tested by the molecular characterization of the USDA103 research strain. Using eight microsatellite loci, the probability of falsely classifying an individual non-USDA103 catfish as a USDA103 was 0.0065. From a sample of 50 fish from a putative USDA103 pond, the probability of falsely including two non-USDA103 fish was 1 x 10(-105), and the conservative probability of falsely excluding two USDA103 fish was 1 x 10(-6). This genotyping system provides channel catfish producers with an objective mechanism for identification and management of genetically selected fish.     

Cloning and characterisation of a channel catfish (Ictalurus punctatus) Mx gene

A 2.5 kb full-length cDNA clone of a channel catfish (Ictalurus punctatus) Mx gene was obtained using RACE (rapid amplification of cDNA ends) polymerase chain reaction (PCR) from RNA extracted from the liver of poly I:C stimulated channel catfish. The gene consists of an open reading frame of 1905 nucleotides encoding a 635 amino acid protein. The predicted protein is 72.5 kDa and contains the dynamin family signature, a tripartite GTP binding motif and a leucine zipper, characteristic of all known Mx proteins. The catfish Mx protein exhibited 79% identity with perch Mx and between 71% and 74% identity with the three Atlantic salmon and the three rainbow trout Mx proteins. Mx mRNA was constitutively expressed in channel catfish ovary (CCO) cells, but in higher quantities in response to poly I:C treatment. Mx was induced in channel catfish following injection with channel catfish virus (CCV) and poly I:C.     

Novel heme-binding component in the serum of the channel catfish (Ictalurus punctatus)

The serum of the channel catfish (Ictalurus punctatus) was examined for heme- and hemoglobin-binding proteins. Electrophoretic mobility retardation assays failed to detect a hemoglobin-binding material similar to mammalian haptoglobin; however, a heme-binding component (not previously described) was identified in catfish seru. The heme-binding component was purified by gel filtration chromatography; electrophoretic analyses suggested it to be composed of two polypeptide subunits of molecular masses about 115 and 98 kDa. This composition is inconsistent with hemopexin, the known heme-binding serum protein of mammals. Although it was not fully saturated with heme, the catfish component contained detectable heme in normal sera. When complexed by the binding material, heme was used as an iron source by isolates of the bacterial Gram-negative genusAeromonas; the capacity of other bacteria to use the complex was not tested. The physiological function of the catfish heme-binding serum protein is presently not clear.     

不同水温下氟甲砜霉素在斑点叉尾鮰体内的药代动力学研究

研究不同水温(18℃和28℃)条件下,单剂量(10mg/kgb·w)强饲氟甲砜霉素,在斑点叉尾鮰(Ictaluruspunc-tatus)体内药代动力学特征.采用高效液相色谱紫外检测法可以同时检测血浆中氟甲砜霉素及其代谢物氟甲砜霉素的浓度.用3p97药代动力学软件处理药时数据.结果表明:在不同水温条件下氟甲砜霉素在斑点叉尾鮰体内的药时数据均符合一室开放式模型.药时规律符合理论方程C血浆=71921(e-0.036t-e-0.18t)和C血浆=91061(e-0.081t-e-0.301t).18℃和28℃的条件下,主要药代动力学参数:吸收半衰期T1/2ka分别为31845h和21301h,消除半衰期T1/2ke分别为191118h和81519h,达峰时间Tpeak分别为111136h和51953h,最大血药浓度Cmax分别为41074μg/mL和41226μg/mL,曲线下面积AUC分别为1741547(μg/mL)/h和811279(μg/mL)/h,平均驻留时间MRT分别为271581h和121290h,相对表观分布容积V/F(c)分别为11580L/kg和115121L/kg.采用氟甲砜霉素防治斑点叉尾鮰细菌性疾病,建议在18℃左右口服10mg/kg体重剂量的氟甲砜霉素,2d给药1次;在28℃左右口服10mg/kg体重剂量的氟甲砜霉素,1d给药1次.试验过程中在斑点叉尾鮰血浆样品中未检测到氟甲砜霉素的主要代谢物氟甲砜霉素胺.       

A standardized microsatellite marker panel for parentage and kinship analyses in channel catfish,Ictalurus punctatus

This research was designed to produce a standardized set of microsatellite loci for parentage and kinship analyses in channel catfish, the leading species of US aquaculture. Three panels of five to six markers each were developed that contained a total of two dinucleotide‐, eight trinucleotide‐ and seven tetranucleotide‐microsatellite loci respectively. The loci had a range of nine to 31 alleles per locus in an outbred population. Based on the allele frequencies measured in commercial randomly bred broodstock, the combined probability of non‐exclusion of an unrelated candidate parent pair was 5.36e‐18. The combined probability of non‐exclusion of unrelated identical genotypes was 2.58e‐08. The microsatellite panels were validated by parentage and kinship evaluation in three populations. A total of 697 spawns were collected from matings of outbred broodstock over three spawning seasons, and parents were determined unambiguously for all but three spawns. Genotype analysis also enabled the identification of half‐sibling and full‐sibling families produced by pond spawning. In a second experiment, parentage was unambiguously determined in nine spawns from a population consisting of broodstock derived from only four families. A third experiment demonstrated that all but one of 374 individuals from 10 full‐sibling families could be assigned to a family after coculture in an earthen pond for 1 year. The standardized microsatellite panels enable the development of pedigreed catfish populations and large‐scale performance evaluations in common environments to support the genetic improvement of cultured catfish through selective breeding.     

A high-affinity zinc-binding plasma protein in channel catfish (Ictalurus punctatus).

1. Channel catfish (Ictalurus punctatus) have a remarkably high concentration of zinc (Zn) in their blood serum, about 20 micrograms/ml. However, compared to mammals, the concentrations of Zn in their tissues are not remarkable. The serum Zn is dialyzable against a solution containing 1 mM EDTA. 2. Following separation of serum proteins by gel-filtration most of the Zn was recovered in a fraction with the same peak volume of elution for the Zn and protein concentrations and having a molecular weight similar to bovine serum albumin. 3. Binding of Zn to such sites was not changed by Cu2+, Cd2+, Ca2+, or La3+. N-ethylemaleimide (NEM) appeared to decrease binding slightly. 4. Equilibrium dialysis with a Scatchard plot analysis of these data suggested that a single set of binding sites was present on the protein(s) with KD of 2 x 10(-5) M. There were binding sites for 35 x 10(-8) M Zn/mg protein. 5. Parallel equilibrium dialysis measurements using human, rabbit and chicken albumins indicated that the catfish serum protein(s) had a much higher affinity and binding capacity for Zn than the albumins in these species. 6. The catfish Zn serum-binding protein may be an albumin. The possible physiological significance of such a serum protein in freshwater fish is discussed.     

Assignment of immune-related genes to the channel catfish, Ictalurus punctatus, genetic map

Eighteen new genes, adenosine A1 receptor (ADORA1), complement component 4-beta (C4b), complement component 8-beta (C8b), chemokine ligand 19 (CCL19), chemokine ligand 21 (CCL21), chemokine ligand 25 (CCL25), chemokine receptor 2 (CCR2), chemokine receptor 5 (CCR5), chemokine receptor 4 (CCR4), chemokine receptor 7 (CCR7), chemokine receptor 9 (CCR9), interleukin 1-beta (IL1B), integrin II-beta (ITGB2), novel immune type receptor 2 (NITR2), novel immune type receptor 4 (NITR4), natural killer cell lysin (NKLYSIN), nucleotide excision repair (RAD23B) and tumour necrosis factor-alpha (TNF), were assigned to the channel catfish (Ictalurus punctatus) genetic linkage map. Polymorphic microsatellite markers were developed for NITR2, NITR4 and RAD23B from short-tandem repeats in the available sequence. Polymorphic microsatellite markers were developed for the remaining 15 genes by short-tandem repeat-anchored primer sequencing of catfish bacterial artificial chromosomes. Two gene clusters (MYOG-NRAMP-ADORA1) and (CCR4-CCR2-CCR5) displayed conservation of synteny between catfish and mammals. Assignment of 18 new genes to the catfish linkage map will further advance integration of genetic and physical maps and comparative mapping between channel catfish and map rich species.