Channel Catfish Ictalurus Punctatus Rafinesque Research Articles

North and South American Haplotypes ofDrepanocephalus auritus(Digenea: Echinostomatidae) Are Released fromBiomphalaria havanensis(Mollusca: Planorbidae) Inhabiting Catfish Aquaculture Ponds in Mississippi, U.S.A.

Trematodes of the subclass Digenea are a major impediment to catfish aquaculture in the southeastern United States. Catfish production ponds are ideal feeding grounds for piscivorous birds, and given the variety of aquatic snails that inhabit these ponds, they offer a prime environment for the propagation of digenetic life cycles. In July 2014, snails morphologically consistent with Biomphalaria havanensis L. Pfeiffer, 1839, were collected from 2 different catfish production ponds in the catfish farming region of eastern Mississippi. These snails were refractory to Schistosoma mansoni Sambon, 1907, infection, and phylogenetic analyses based on internal transcribed spacer (ITS)1 and ITS2 fragments placed the snails within the B. havanensis/obstructa complex. Some (1.5%) of these snails shed cercariae morphologically and molecularly consistent with Drepanocephalus auritus Kudlai, Kostadinova, Pulis, and Tkach, 2015 (formerly reported as Drepanocephalus spathans Dietz, 1909), an echinostomatid parasite of the double-crested cormorant Phalacrocorax auritus Lesson, 1831, and channel catfish Ictalurus punctatus Rafinesque, 1818. Juvenile channel catfish were challenged individually with ∼275 cercariae of D. auritus per fish, resulting in limited mortality (2 out of 10 fish). Surviving fish were euthanatized 7 d postchallenge, and the presence of metacercariae was confirmed histologically. Parasite-associated pathology was consistent with previous studies. Subsequent molecular analysis of 5 different gene targets confirmed morphological identifications. Previous research has suggested the existence of discrete North American and South American haplotypes of D. auritus. Mitochondrial cytochrome c oxidase subunit 1 and nicotinamide adenine dinucleotide dehydrogenase subunit 1 sequences demonstrated that both haplotypes were released by snails in this study, suggesting a broader distribution of these genetic variants than previously thought. Along with Planorbella trivolvis Say, 1817, this work identifies a second snail species common to catfish aquaculture ponds that releases D. auritus infective to juvenile channel catfish and is the first report of B. havanensis as an intermediate host for D. auritus in North America.

First Description of supernumerary Chromosomes in Ictaluruspunctatus Rafinesque 1818 Reveals Active Ribosomal Genes in the B Complement.

The North American channel catfish Ictalurus punctatus Rafinesque 1818 is cultivated in the United States, Asia and Brazilian fish farms, and also utilized as a model species in aquaculture and genetic studies. In this work, cytogenetic analysis of . punctatus from Brazilian aquaculture revealed for the first time the presence of extra elements (supernumerary or B chromosomes) in this species. These elements were characterized as dot-like micro B chromosomes and were found in three individuals (varying from 0 to 1) and in one individual with higher incidence per cell (varying from 0 to 5; mean number of Bs per cell = 2.01). More specific cytogenetic techniques in this individual revealed 58 A chromosomes (standard complement) containing heterochromatic bands in the centromeric regions, a single Ag-NOR in a subtelocentric pair (also positive for 18S rDNA using the FISH technique) and multiple 5S rDNA clusters in three different subtelocentric chromosomes. Four B chromosomes were entirely Ag-NOR positive (also fully heterochromatic) and three presented 18S rDNA clusters by FISH. The occurrence of Ag-NOR and 18S ribosomal genes in both A and B chromosome complements may indicate an intraspecific origin for these extra chromosomes. Additionally, the terminal location of 18S ribosomal clusters in the Ag-NOR-bearing chromosomes and the presence of active NOR in the B chromosomes suggested that breakage events may be related to a possible recent origin of these extra elements. We suggest this data may be useful as cytogenetic information for future elucidation of the composition, origin and evolution of extra chromosomes in fishes.

Multiplex-PCR for simultaneous detection of 3 bacterial fish pathogens, Flavobacterium columnare, Edwardsiella ictaluri, and Aeromonas hydrophila

A multiplex PCR (m-PCR) method was developed for simultaneous detection of 3 important fish pathogens in warm water aquaculture. The m-PCR to amplify target DNA fragments from Flavobacterium columnare (504 bp), Edwardsiella ictaluri (407 bp) and Aeromonas hydrophila (209 bp) was optimized by adjustment of reaction buffers and a touchdown protocol. The lower detection limit for each of the 3 bacteria was 20 pg of nucleic acid template from each bacteria per m-PCR reaction mixture. The sensitivity threshold for detection of the 3 bacteria in tissues ranged between 3.4 x 10(2) and 2.5 x 10(5) cells g(-1) of tissue (channel catfish Ictalurus punctatus Rafinesque). The diagnostic sensitivity and specificity of the m-PCR was evaluated with 10 representative isolates of each of the 3 bacteria and 11 other Gram-negative and 2 Gram-positive bacteria that are taxonomically related or ubiquitous in the aquatic environment. Except for a single species (A. salmonicida subsp. salmonicida), each set of primers specifically amplified the target DNA of the cognate species of bacteria. m-PCR was compared with bacteriological culture for identification of bacteria in experimentally infected fish. The m-PCR appears promising for the rapid, sensitive and simultaneous detection of Flavobacterium columnare, E. ictaluri and A. hydrophila in infected fish compared to the time-consuming traditional bacteriological culture techniques.

Neoergasilus japonicus (Poecilostomatoida: Ergasilidae), a Parasitic Copepod New to North America

Adult, gravid female Neoergasilus japonicus Harada, 1930 are described from several species of fish from Lee County, Alabama. Samples of bluegill Lepomis macrochirus Rafinesque (n = 25), largemouth bass Micropterus salmoides Lacépéde (n = 6), redear sunfish Lepomis microlophus Gunther (n = 5), and channel catfish Ictalurus punctatus Rafinesque (n = 1) were collected between November 1993 and May 1995. Prevalence of infection was 100% in all fish collected. The dorsal fin was the site of infection containing the highest number of parasites and the anal fin showed the highest frequency of infection. Morphological comparisons are made between this report and previous descriptions, and disparities among them are indicated. New hosts for N. japonicus include largemouth bass, channel catfish, and redear sunfish. This report is the first North American record for the genus Neoergasilus.

Nitrite-induced anemia in channel catfish, Ictalurus punctatus rafinesque.

Since 1983 numerous cases of anemia have been reported in populations of channel catfish Ictalurus punctatus Rafinesque cultured in the southeastern United States. Environmental nitrite-nitrogen concentrations of 4 mg/L or more occur sporadically in channel catfish culture ponds, and the frequency of occurrence is greatest in the fall and spring. The authors have observed that some cases of anemia in populations of pond-raised channel catfish follow prolonged exposure to high concentrations of environmental nitrite. However, there was no evidence that exposure of channel catfish to environmental nitrite was the cause of the observed anemia. Hemolytic anemia following nitrite exposure has been described for sea bass Dicentrarchus labrax (L.) and rainbow trout Salmo gairdneri, but not for channel catfish. In the present study the authors show that a variable, but generally mild, anemia develops in channel catfish exposed to nitrite. They also offer a management procedure for preventing the development of anemia during periods of elevated environmental nitrite concentrations.

The bone compartment in a teleost fish, Ictalurus punctatus: size, composition and acid-base response to hypercapnia.

An estimate of the total mass of bone in the Channel catfish Ictalurus punctatus Rafinesque, was obtained by dissection. The wet weight of bone constituted 16.3 +/- 1.9% (+/- S.D.) of the total (live) wet weight, and 25.0 +/- 2.1% of the dry weight. Of the dry skeletal material, 66.3 +/- 11.1% was soluble in strong acid. The acid-soluble material was about half mineral salts, consisting of 19.5 +/- 2.21% Ca2+ and 27.6 +/- 3.22% PO4(3-), with minor fractions of Mg2+ (0.33%) and CO3(2-) (1.67%). The pH values of fluid compartments associated with skull and vertebral bone tissues were 7.420 +/- 0.026 and 7.444 +/- 0.017 (+/- S.E.), respectively, at a normocapnic plasma pH of 7.868 +/- 0.020. In response to external hypercapnia (7.5 Torr), the blood response consisted of an immediate decrease in pH, and a subsequent compensatory rise in both pH and [HCO3-]. This compensatory phase was accompanied by a net apparent H+ excretion to the water. The participation of the mineral salts of the bone compartment in compensation appeared to be negligible, since there was no significant change in either blood [Ca2+] or [PO4(3-)], nor any significant increase in calcium efflux to the water. The intracellular pH values of the bone compartments were only slightly higher than other tissues, and the changes in pHi during hypercapnia were similar in bone and white muscle. Thus, the bone compartment in the fish appears to be well regulated, relatively refractory to acute acid-base disturbance, and does not serve as an ion source during acid-base compensation.