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At least 19 recordsLinked to original sources
PubMed1998

Inheritance and usefulness of AFLP markers in channel catfish (Ictalurus punctatus), blue catfish (I. furcatus), and their F1, F2, and backcross hybrids.

Eight primer combinations were used to investigate the application of amplified fragment length polymorphism (AFLP) markers in catfish for genetic analysis. Intraspecific polymorphism was low among channel catfish or blue catfish strains. Interspecific AFLP polymorphism was high between the channel catfish and blue catfish. Each primer combination generated from 70 to more than 200 bands, of which 38.6 75.7% were polymorphic between channel catfish and blue catfish. On average, more than 20 polymorphic bands per primer combination were produced as quality markers suitable for genetic analysis. All AFLP markers were transmitted into channel catfish x blue catfish F1 hybrids, except rare markers that were heterozygous in the parents and therefore were segregating in F1 hybrids. The two reciprocal channel catfish x blue catfish F1 hybrids (channel catfish female x blue catfish male; blue catfish female x channel catfish male) produced identical AFLP profiles. The AFLP markers were inherited and segregated in expected Mendelian ratios. At two loci, E8-b9 and E8-b2, markers were found at significantly lower frequencies than expected with F2 and backcross hybrids which had been selected for increased growth rates. The reproducibility of AFLP was excellent. These characteristics of the catfish AFLP markers make them highly useful for genetic analysis of catfish, especially for construction of genetic linkage and quantitative trait loci maps, and for marker-assisted selection.

Animals↗
PubMed2006

Repeat structure of the catfish genome: a genomic and transcriptomic assessment of Tc1-like transposon elements in channel catfish (Ictalurus punctatus).

We have assessed the distribution and diversity of members of the Tc1/mariner superfamily of transposable elements in the channel catfish (Ictalurus punctatus) genome as well as evaluating the extent of transcription of Tc1 transposases in the species. Through use of PCR amplification and sequencing, assessment of random BAC end sequences (BES) equivalent to 1.2% genome coverage, and screening of over 45,000 catfish ESTs, a significant proportion of Tc1-like elements and their associated transcripts were captured. Up to 4.2% of the catfish genome in base pairs appears to be composed of Tc1-like transposon-related sequences and a significant fraction of the catfish cellular mRNA, approximately 0.6%, was transcribed from transposon-related sequences in both sense and antisense orientations. Based on results of repeat-masking, as much as 10% of BAC end sequences from catfish, which is a random survey of the genome, contain some remnant of Tc1 elements, suggesting that these elements are present in the catfish genome as numerous, small remnants of the transposons. Phylogenetic analysis allowed comparison of catfish Tc1 transposase types with those found in other vertebrate and invertebrate species. In spite of the existence of many types of Tc1-like sequences that are not yet able to be placed in clades with strong statistical support, it is clear that multiple families of Tc1-like elements exist in channel catfish.

Animals↗
PubMed2001

Complete nucleotide sequence of the cytochrome b gene of channel catfish Ictalurus punctatus and comparison of sequence homology among channel catfish and other fishes.

To clarify the phylogenic relationship of channel catfish with other fishes, the cytochrome b (Cyt b) gene of the catfish was cloned and sequenced. Channel catfish (Ictalurus punctatus) belonging to the family Ictaluridae in the order Siluriformes showed a 78.4-87.4% similarity to all but one fish of the family Cyprinidae and river loach Crossostoma lacustre of the family Balitoridae in the order Cypriniformes in which genes had already been sequenced, and a 97.2% similarity to the goldfish (Carassius auratus) belonging to the family Cyprinidae. Within the family Cyprinidae, a 78.8-89.2% similarity to one another was recorded. In addition, the similarity rate between the family Cyprinidae and the family Balitoridae reached a value of 77.8-79.9% in the order Cypriniformes. Furthermore, in an unrooted phylogenetic tree consisting of four branches among eight fishes, channel catfish and goldfish appeared in the same branch. These results suggested that the Cyt b gene of the channel catfish in the order Siluriformes was closely related to that of a goldfish in the order Cypriniformes. The results were not agreement with the morphological classification. Genetic reclassification of the fishes may be necessary to identify the ancestor. This is the first report on the cloning and complete sequencing the Cyt b gene of the channel catfish which may contribute to the genetic reclassification of catfishes belonging to the order Siluriformes.

Amino Acid Sequence↗
PubMed1992

Structure-function studies of five natural, including catfish and dogfish, gonadotropin-releasing hormones and eight analogs on reproduction in Thai catfish (Clarias macrocephalus).

Five distinct forms of gonadotropin-releasing hormone (GnRH) and their analogs, six of which are newly designed, were used to study reproduction in Thai catfish, Clarias macrocephalus. Determination was made for the percentage of fish that ovulated within 16-18 h; the percentage of eggs fertilized; and the percentage of larva that hatched and survived for 7 days. The results show, firstly, that natural chicken GnRH-II, which is identical with catfish GnRH-II, was significantly more effective at a dose of 300 micrograms/kg than the control injection for the induction of ovulation. Dogfish GnRH at the same dose was also significantly more effective than the control, but was not significantly different from chicken (catfish) GnRH-II for ovulation induction. The novel catfish GnRH-I, mammalian GnRH and salmon GnRH were not effective at 100, 150 or 300 micrograms/kg in Thai catfish. Secondly, 5 of 8 analogs of GnRH at a dose of 20 micrograms/kg resulted in a significantly higher percentage of ovulating fish compared with the control fish. Among these five analogs, the most effective were the two analog forms of chicken GnRH-II (D-Arg6,Pro9 NEt and D-Nal6,Pro9 NEt), followed by the salmon GnRH analog (D-Arg6,Pro9 NEt), a dogfish GnRH analog (D-Arg6,Pro9 NEt) and the mammalian GnRH analog (D-Ala6,Pro9 NEt). Not significantly different from the controls were the two catfish GnRH-I analogs and one of the dogfish (D-Nal6,Pro9 NEt) analogs. The six new analogs had not been previously tested in any animal. Thirdly, the number of fish ovulating was the same whether GnRH was administered in one or two injections.

Amino Acid Sequence↗
PubMed1994

Isolation, characterization and expression of cDNAs encoding the catfish-type and chicken-II-type gonadotropin-releasing-hormone precursors in the African catfish.

The cDNAs encoding the catfish prepro-gonadotropin-releasing hormone and the chicken prepro-gonadotropin-releasing hormone II of the African catfish (Clarias gariepinus) have been isolated and sequenced. The catfish gonadotropin-releasing-hormone precursor and the chicken gonadotropin-releasing-hormone-II precursor have the same overall architecture as other gonadotropin-releasing-hormone precursors identified so far; each is composed of a signal peptide, gonadotropin-releasing hormone and a gonadotropin-releasing-hormone-associated peptide which is connected to gonadotropin-releasing hormone and chicken gonadotropin-releasing hormone II, in combination with the Gly-Lys-Arg sequence, are highly conserved during evolution when compared with the corresponding regions of mammalian, avian (chicken gonadotropin-releasing hormone I) and other fish gonadotropin-releasing-hormone precursors. However, the gonadotropin-releasing-hormone-associated peptide regions are markedly divergent. Northern-blot analysis revealed the presence of a single catfish gonadotropin-releasing-hormone mRNA species of about 470 bases, and the presence of a single chicken gonadotropin-releasing-hormone-II mRNA species of about 650 bases in the African catfish brain. In situ hybridization revealed catfish gonadotropin-releasing-hormone cell bodies rostro-caudally scattered in the olfactory nerve, along both sides of the midline of the telencephalon, in the preoptic area of the ventral hypothalamus, and in the infundibular stalk close to the pituitary. Chicken gonadotropin-releasing-hormone-II cell bodies, however, were exclusively found in the midbrain tegmentum.

Amino Acid Sequence↗
PubMed1992

Influence of dihydrotestosterone on sex determination in channel catfish and blue catfish: period of developmental sensitivity.

Treatment of channel catfish with 0.2, 20, or 200 mg/liter of dihydrotestosterone (DHT) in the water during the egg stage or during egg and sac-fry stages did not alter the expected 1:1 sex ratio of the progeny. Feeding DHT at 200 mg/kg of feed for the first 21 days after yolk sac absorption resulted in 80% females; this proportion was increased by combining feeding with treatment of 200 mg DHT/liter in the sac-fry stage (90%) or in the egg and sac-fry stage (97%). In contrast, treatment of blue catfish sac-fry with 200 mg DHT/liter, with or without the combination of feeding DHT at 200 mg/kg food, resulted in 100% female populations. Neither clomiphene citrate, an estrogen-receptor blocking agent, nor clofibrate, an inhibitor of hepatic synthesis of cholesterol, affected the sex ratio of channel catfish, and neither of these compounds altered the feminizing effect of 200 mg DHT/kg when fed in combination with DHT. The nonaromatizable androgen DHT is not as effective as many other androgens in producing paradoxical female populations of channel catfish. However, feminization of blue catfish by treatment of sac-fry indicates that this species is more susceptible to hormonal manipulation and that the period of sex determination may occur earlier in development than in channel catfish.

Animals↗
PubMed1998

Channel catfish reovirus (CRV) inhibits replication of channel catfish herpesvirus (CCV) by two distinct mechanisms: viral interference and induction of an anti-viral factor.

Catfish reovirus (CRV), a double stranded RNA virus, inhibited channel catfish herpes-virus (CCV) replication by 2 different mechanisms: (1) directly as a consequence of its own replication, and (2) indirectly due to the induction of an anti-viral factor. In the former, prior infection with CRV significantly reduced subsequent CCV protein synthesis and virus yield. CRV mediated-interference was greatest when CRV infection preceded CCV infection by 16 h, and was least when cell cultures were simultaneously infected with both viruses. in the latter case, the infection of channel catfish ovary (CCO) cultures with UV-inactivated CRV resulted in the synthesis (or release) of an anti-viral factor. Cells producing the factor were protected from CCV infection, as were cells which had been treated with spent culture medium containing anti-viral activity. Interestingly an anti-viral activity was constitutively present in long-term cultures of catfish T-cells and macrophages. Whether this factor and the one induced by UV-inactivated CRV are identical is not known, but analogy to mammalian systems suggests that the former may be similar to type II interferon, whereas the latter may be the piscine equivalent of type I interferon. These results suggest that UV-inactivated CRV may prove useful in the induction and characterization of interferon-like anti-viral proteins in the channel catfish and that long-term cultures of catfish T-cells and monocytes may serve as a ready source of additional anti-viral factors.

Animals↗
PubMed1987

Quantitative studies of steroid bioconversions in the seminal vesicles of spawning male African catfish, Clarias gariepinus (Burchell), under natural conditions, and of non-spawning catfish under natural and fish farm conditions.

1. Steroid bioconversions in the seminal vesicles of Clarias gariepinus were studied quantitatively in vitro by tissue incubations with [3H]pregnenolone, [3H]androstenedione and [14C]11 beta-hydroxyandrostenedione, respectively. 2. Spawning and non-spawning catfish, collected in the Hula nature reserve in northern Israel during the spawning period, and non-spawning animals, collected from a fish pond in the same region during the same period, were studied. 3.Spawning animals showed a significantly higher production of 17 alpha-hydroxyprogesterone, 5 beta-pregnan-17 alpha-ol-3,20-dione and 5 beta-reduced androgens than non-spawning feral and pond catfish, as a result of a significantly increased contribution of the enzymes 5 beta-reductase and 3 alpha-hydroxysteroid dehydrogenase (HSD). 4. In spawning catfish the concentration of gonadotropin in blood plasma were also significantly higher than in the plasma of non-spawning feral and pond catfish. This increase in gonadotropin level might have induced the rise in enzyme activity of 5 beta-reductase and 3 alpha-HSD. 5. It is concluded that the absence of a shift in steroidogenesis towards the production of 5 beta-reduced steroids may be among the factors preventing spontaneous spawning in male African catfish under husbandry conditions.

Androstenedione↗
PubMed2003

Channel catfish virus gene expression in experimentally infected channel catfish, Ictalurus punctatus (Rafinesque).

Channel catfish virus (CCV) produces an acute haemorrhagic disease in fingerling channel catfish and establishes latent infection in fish that survive the primary infection. This study investigated CCV gene expression in tissues of experimentally infected fish. Reverse transcriptase polymerase chain reaction assays were developed for detection of transcripts expressed by each of the CCV direct repeat region genes in CCV-infected channel catfish ovary cells and in tissues of infected fish. Immediate-early, early and late gene transcripts were detected in the blood, brain, kidney and liver tissues of acutely infected catfish demonstrating active viral replication in multiple tissues during the early stages of CCV infection. However, there was no evidence for viral replication by 24 days post-infection in tissues of fish that survived the acute disease. Viral latency-associated transcripts encoded by CCV direct repeat genes were not detected in latently infected catfish. The results of this study provide a foundation for further studies to investigate the molecular basis of CCV pathogenesis and latency.

Animals↗
PubMed2003

The Edwardsiella ictaluri O polysaccharide biosynthesis gene cluster and the role of O polysaccharide in resistance to normal catfish serum and catfish neutrophils.

Edwardsiella ictaluri, the causative agent of enteric septicaemia of catfish (ESC), expresses long O polysaccharide (OPS) chains on its surface. The authors previously reported the construction of an isogenic Ed. ictaluri OPS mutant strain and demonstrated that this strain is avirulent in channel catfish. This paper reports the cloning of the Ed. ictaluri OPS biosynthesis gene cluster and identification of the mutated gene in the OPS-negative strain. The sequenced region contains eight complete ORFs and one incomplete ORF encoding LPS biosynthesis enzymes. The mutated gene (designated wbiT) was similar to other bacterial galactose-4-epimerases. Glycosyl composition analysis indicated that wild-type Ed. ictaluri OPS contains higher amounts of galactose and N-acetylgalactosamine than the OPS mutant strain, which correlated well with predicted functions of the genes identified in the OPS biosynthesis cluster. The OPS mutant had a relatively small, but significant, decrease in its ability to survive in normal catfish serum compared to wild-type Ed. ictaluri, but it retained the ability to resist killing by catfish neutrophils.

Animals↗
PubMed2003

Both recombinant African catfish LH and FSH are able to activate the African catfish FSH receptor.

LH and FSH are heterodimeric glycoprotein hormones, composed of a common alpha-subunit non-covalently associated with a hormone-specific beta-subunit. Repeated efforts to isolate catfish FSH (cfFSH) have not been successful and only catfish LH (cfLH) has been purified from catfish pituitaries. Recently, however, we succeeded in cloning the cDNA encoding the putative cfFSHbeta; the cDNAs for the alpha- and beta-subunit of cfLH have been cloned before. Here we report the expression of biologically active cfLH and cfFSH in the soil amoeba, Dictyostelium discoideum. The biological activity of the recombinant hormones was analyzed using cell lines transiently expressing either the cfLH receptor or the cfFSH receptor. Moreover, a primary testis tIssue culture system served to study the steroidogenic potency of the recombinant hormones. Our results demonstrated that Dictyostelium produced biologically active, recombinant catfish gonadotropins, with recombinant cfLH being almost indistinguishable from its native counterpart, purified from pituitaries. Although recombinant cfFSH has significant effects in the bioassays used in this study, the specific function of native cfFSH in the control of reproduction and its expression patterns are not yet understood.

Androstenedione↗
PubMed1993

Productive infection of continuous lines of channel catfish leukocytes by channel catfish virus.

Channel catfish virus (CCV) undergoes extensive replication in fingerling catfish and establishes latent infection in survivors. Although the site of viral latency in carriers is unknown, a variety of tissues, including leukocytes, have been implicated. To explore the interaction of CCV and leukocytes further, we examined in vitro infection of continuous lines of cloned catfish B cells and non-cloned lines containing predominantly macrophages and putative T-cells. Our results indicate that all three leukocyte subpopulations were productively infected with CCV, but that the kinetics of infection and the final yields differed markedly. These findings shed light on CCV-leukocyte interaction and suggest that CCV-infected autologous macrophage or T-cell lines might be suitable targets for assays of catfish cytotoxic T cell activity.

Animals↗
PubMed2004

Multiple CC chemokines in channel catfish and blue catfish as revealed by analysis of expressed sequence tags.

Chemokines represent a superfamily of chemotactic cytokines involved in recruitment, activation and adhesion of a variety of leukocyte types to inflammatory foci, as well as in the organization and maintenance of lymphoid organ architecture and in normal developmental processes. Nearly all chemokines have been identified in human and mouse, but only a handful of fish chemokines have been identified. Here we describe 14 distinct chemokines from channel catfish and blue catfish identified by analysis of 30,000 expressed sequence tags. Based on sequence analysis, sequence similarity, and the arrangement of the conserved cysteine residues, all 14 chemokines were identified as members of the CC subfamily. Phylogenetic analysis did not reveal clear evidence of orthology of the catfish and human or mouse chemokines. Similarity analysis indicated that nine of the 14 CC chemokines were identified for the first time in fish. The availability of this pool of catfish CC chemokines should facilitate rapid identification and phylogenetic analysis of CC chemokines from other fish and related species.

Animals↗
PubMed2002

Protective immunity induced by DNA vaccination of channel catfish with early and late transcripts of the channel catfish herpesvirus (IHV-1).

Seven full-length transcripts encoding four early and three late genes of the channel catfish virus (CCV), ictalurid herpesvirus I (IHV-1), have been cloned following rt-PCR amplification and DNA sequencing. Transcripts were selected based on their predicted association with membrane structures, identification as an envelope glycoprotein, or as a viral capsid protein. The transcripts derived from ORF 6, ORF 7, ORF 8a, ORF 10, ORF 51, ORF 53, and ORF 59 were all shown to be complete and unspliced. Each of the seven ORFs was cloned into a vaccine expression vector designed to support high levels of expression of the inserted sequence in catfish tissues. Solutions of DNA containing one each of the seven CCV ORFs, vector alone or PBS were injected intramuscularly into 4-8 cm catfish. Four to 6 weeks after injection each experimental group was challenged with one LD(50) of CCV. Single injections of DNA expression constructs containing ORF 59, encoding the envelope glycoprotein, or ORF 6, encoding a presumptive membrane protein, were found to elicit the strongest resistance to challenge compared to uninjected, PBS injected or vector injected groups. Even more effective was a combination vaccine pair in which both ORF 59 and ORF 6 expression constructs were injected. Other ORFs did not provide consistent protection to challenge above that observed in control fish. Both percent survival and kinetics of cumulative deaths were improved using the combination DNA vaccine encoding ORF 6 and ORF 59. Both ORF 6 and ORF 59 were able to elicit virus neutralizing antibodies capable of an anamnestic response on viral challenge. We believe this evidence provides adequate proof of principle for the use of DNA vaccines in channel catfish and the effectiveness of the resistance to viral infection they elicit.

Animals↗
PubMed1999

Detection of channel catfish virus DNA in latently infected catfish.

Channel catfish virus (CCV) disease is an acute haemorrhagic disease in juvenile channel catfish (Ictalurus punctatus). While fish that survive primary CCV infection are suspected of being carriers of CCV, little is known concerning CCV latency. In this report, fingerling catfish were infected with CCV by experimental immersion challenge. Infected fish displayed clinical signs of CCV disease, but 22% of infected fish survived the acute disease. At 140 days post-infection, PCR analysis detected CCV DNA in the blood, brain, intestines, kidney, liver and peripheral blood leukocytes of latently infected fish. Further analysis indicated the CCV genome may exist as circular or concatemeric DNA during virus latency. This study, employing an experimental model of CCV disease, confirms that CCV establishes a latent infection of channel catfish.

Animals↗
PubMed2004

Susceptibility of channel catfish fry to Channel Catfish Virus (CCV) challenge increases with age.

Susceptibility of channel catfish to Channel Catfish Virus Disease (CCVD) has been generally considered to be inversely related to age. However, in experimental immersion challenges, we found that channel catfish fry, 3 to 8 d post hatch (dph), are most resistant to CCV and susceptibility increases with age. Initial studies involved 2 spawns that had high CCV carrier percentage. To determine if the resistance seen in the fry was related to the CCV carrier status of the parents, we selected 4 spawns from CCV negative parents and 2 spawns from CCV positive parents and immersion challenged them at 8, 23, 36 and 60 dph with 0, 2.5 x 10(4) or 2.5 x 10(6) plaque forming units (PFU) of CCV l(-1). Survivors of the low-dose exposed groups were rechallenged at 120 dph with 2.5 x 10(6) PFU CCV l(-1). Each brood demonstrated increasing susceptibility to CCVD with age and only the fish that were initially exposed at 60 dph developed protective immunity. Time course assays evaluating tissue levels of virus in channel catfish exposed to CCV at 7, 21 and 42 dph suggested that the resistance was an early event in the infection process. The resistance in fry was most pronounced in fish from CCV positive spawns and was correlated to neutralizing antibody titers in the maternal parent in the 8 dph challenge. However, other factors may be involved because all groups displayed the initial resistance and subsequent susceptibility to CCVD. The age effect may be an important influence on the progression of CCVD outbreaks and indicates the need to consider age for experimental challenges. Additionally, we documented the level of vertical transmission of CCV. Fry from the 4 positive spawns had a CCV prevalence of 40 to 75 %.

Age Factors↗
PubMed2001

On the osteology and myology of catfish pectoral girdle, with a reflection on catfish (Teleostei: Siluriformes) plesiomorphies.

The configuration of the pectoral girdle bones and muscles of numerous catfishes was studied in detail and compared with that of other siluriforms, as well as of other teleosts, described in the literature. The pectoral girdle of catfishes is composed of only three bones, which probably correspond to the posttemporo-supracleithrum (posttemporal + supracleithrum), scapulo-coracoid (scapula + coracoid), and cleithrum of other teleosts. These latter two bones constitute the place of origin of the pectoral girdle muscles. Two of these muscles are related to the movements of the pectoral fin. These two muscles correspond, very likely, to the abductor superficialis and to the adductor superficialis of other teleostean fishes. In relation to the pectoral spine (thickened first pectoral fin ray), it is usually moved by three well-developed muscles, which are probably homologous with the arrector ventralis, arrector dorsalis, and abductor profundus of nonsiluriform teleosts. The morphological diversity and the plesiomorphic configuration of these muscles, as well as of the other catfish pectoral girdle structures, are discussed.

Animals↗