Comparison of growth performance among channel-blue hybrid catfish, ccGH transgenic channel catfish, and channel catfish in a tank culture system

Abstract

Fish is an essential source of high-quality protein for people worldwide. The present study was designed to compare the growth performance among the channel-blue hybrid catfish, channel catfish transgenic for the channel catfish growth hormone (ccGH) cDNA driven by the antifreeze protein promoter from an ocean pout Zoarces americanus (opAFP-ccGH), and non-transgenic channel catfish control. Mean body weight of channel-blue hybrid catfish was 15.80 and 24.06% larger than non-transgenic channel catfish control at 4 and 18 months of age, respectively. However, transgenic opAFP-ccGH channel catfish were 5.52 and 43.41% larger than channel-blue hybrid catfish and 22.19 and 77.91% larger than their controls at 4 and 18 months of age, respectively. Significant differences in mean body weight between the sexes within all genetic types were found. Males were larger than females (P < 0.001). However, mean body weight of non-transgenic males was not larger than transgenic opAFP-ccGH females or male and female hybrid catfish. Condition factor of transgenic opAFP-ccGH channel catfish was higher (P < 0.05) than that of full-sibling, non-transgenic channel catfish and hybrid catfish. The mean percentage body weight gain of GH transgenic channel catfish was 559%, the channel-blue hybrid catfish was 384.9% and their non-transgenic controls channel catfish was 352.6%.

Figure 1

Comparison of different genetic groups of the F₁ generation of hybrid catfish, transgenic channel catfish containing channel catfish growth hormone (ccGH) cDNA driven by the ocean pout Zoarces americanus antifreeze protein promoter, and channel catfish. (a) mean final body weight (g) ± SD, and (b) condition factor ± SD. Fish were 18 months of age. Fish were reared in a 100-L tank at 500 fish/tank. Treatments, Hybrid = the channel catfish, Ictalurus punctatus, ♀ × blue catfish, I. furcatus, ♂ hybrid catfish, opAFP-ccGH (T) = channel catfish transgenic for channel catfish growth hormone (ccGH) cDNA driven by the ocean pout antifreeze protein promoter, opAFP-ccGH (N) = channel catfish non-transgenic for channel catfish growth hormone (ccGH) cDNA driven by the ocean pout antifreeze protein promoter. Means that do not differ at P = 0.05 are followed by the same superscript (Duncan’s multiple range test) among different genetic groups (P < 0.0001).

Figure 2

Comparison of male and female F₁ channel catfish, Ictalurus punctatus, ♀ × blue catfish, I. furcatus, ♂ hybrid catfish, transgenic channel catfish containing channel catfish growth hormone (ccGH) cDNA driven by the ocean pout Zoarces americanus antifreeze protein promoter, and full-sibling control channel catfish. (a) mean final body weight (g) ± SD, and (b) condition factor ± SD. Fish were 18 months of age. Fish were reared in a 100-L tank at 500 fish/tank. Treatments, Hybrid = the channel catfish, Ictalurus punctatus, ♀ × blue catfish, I. furcatus, ♂ hybrid catfish, opAFP-ccGH (T) = channel catfish transgenic for channel catfish growth hormone (ccGH) cDNA driven by the ocean pout antifreeze protein promoter, opAFP-ccGH (N) = channel catfish non-transgenic for channel catfish growth hormone (ccGH) cDNA driven by the ocean pout antifreeze protein promoter. Means that do not differ at P = 0.05 are followed by the same superscript (Duncan’s multiple range test).

Figure 3

Kansas random (KR) swim bladder of a channel catfish, Ictalurus punctatus, (a) compared with that of a similar-sized channel catfish ♀ × blue catfish, I. furcatus, ♂ hybrid catfish (b). Channel catfish have a single lobed, heart shaped swim bladder. The channel catfish ♀ × blue catfish ♂ hybrid catfish has a bi-lobed swim bladder, but the first anterior chamber has a large, heart-shaped lobe while the second posterior lobe is a small, attached protrusion. (Photographs by Nermeen Y. Abass).

Figure 4

Example of PCR analyses of the F₁ KR generation of transgenic and non-transgenic (full-sibling) channel catfish, Ictalurus punctatus, total DNA. Analysis of channel catfish growth hormone (ccGH) cDNA; 332 bp. 1:14 = different DNA samples from the F₁ KR generation of transgenic and non-transgenic (full-sibling) containing channel catfish growth hormone (ccGH) cDNA driven by the ocean pout Zoarces americanus antifreeze protein promoter (18 months); +  = positive control, plasmid DNA; − = negative control, DNA sample from non-transgenic (wild-type) control fish;  W  =  water control, PCR reaction of water served as negative control; and marker lanes contain 1 Kb plus DNA ladders (Invitrogen). This figure was cropped, and the full-length gel is presented in Supplementary Fig. S1. PCR products visualized with a Molecular Imager Gel Doc XR + System using Image Lab Software (Bio-Rad Laboratories, Inc, Hercules, CA). (Photograph by Nermeen Y. Abass).