Cytogenetic analysis of hybrids and hybrid triploids between the river puffer, Takifugu obscurus , and the tiger puffer, Takifugu rubripes

Abstract

Cytogenetic analyses of the river puffer, Takifugu obscurus, the tiger puffer, Takifugu rubripes and hybrids produced between female T. obscurus and male T. rubripes and their hybrid triploids (produced by cold shock treatment at 4°C) were performed.T. obscurus had 2n = 44 chromosomes and 1.84 AE 0.019 pg DNA/cell, T. rubripes had 2n = 44 and 2.64 AE 0.015, the hybrids had 2n = 44 and 2.15 AE 0.010 and the hybrid triploids had 3n = 66 and 3.22 AE 0.010. The erythrocyte values of the hybrids were more similar to those for T. obscurus, whereas the hepatocyte, midgut and proximal tubule kidney cell values of the hybrids fell down between those for the parental species (p < .05). The erythrocyte, proximal tubule, hepatocyte and midgut epithelial cell sizes for the hybrid triploids were 1.5-fold larger than those for the hybrids (p < .05). The thickness of retina and each layer in the hybrid triploids were 1.1-fold larger than those of the hybrids (p < .05) and did not differ significantly among T. obscurus, T. rubripes and the hybrids (p > .05); however, the hybrid triploids had fewer cell nucleus outer layers than the hybrids (p < .05). Gonad development in the hybrids and hybrid triploids was less matured than in T. obscurus and T. rubripes. The metaphase nucleolus organizer regions (NORs) and the gill cells of T. obscurus, T. rubripes and the hybrids contained two satellite telocentrics, whereas the hybrid triploids contained three satellite telocentrics.

Various Characteristics of Hybrid between River Puffer, Takifugu obscurus and Tiger Puffer, T. rubripes, and Their Hybrid Triploid

“…Production of river puffer, Takifugu obscurus, tiger puffer, T. rubripes , hybrids and hybrid triploids was carried out in the Chungnam Fisheries Research and Development Institute, Chungnam, Korea according to the method of Yoo et al (2016) . River puffer and tiger puffer were injected with1,000 IU/g BW human chorionic gonadotropin (HCG, Sigma, USA).…”

“…Five minutes after fertilization, a total of 3,000 fertilized eggs were subjected to cold-shock treatment (4℃) for 25 min. to prevent extrusion of the second polar body ( Yoo et al, 2016 ). Induced hybrid triploid juveniles were determined by using flowcytometry (Partec, DE / PA, Germany).…”

“…The induction of triploids has been used to generate sterility for applications in commercial farming and fishery management ( Benfey, 1999 ; Felip et al, 2001 ; Feindel et al ., 2011). Triploidy focuses on somatic growth instead of sexual maturation, thus impairing gametogenesis, retarding gonad development and restricting reproduction ( Thorgaard, 1986 ; Nam et al, 2004 ; Feindel et al., 2011 ; Yoo et al, 2016 ). Additionally, sterility in triploids may be used to prevent the decline in flesh quality associated with sexual maturation ( Wang et al., 2015 ).…”

“…Thus, hybrid triploids produced by hybridization and ploidization have been introduced to aquaculture making it possible to integrate the two features of hybrid and triploids ( Nam et al, 2004 ; Rahi & Shah, 2012 ; Huang et al, 2016 ; Yoo et al, 2016 ). Hybrid triploids are expected to have the combined traits of hybrids and triploids, and be more sterile than hybrid diploids and triploids because of the added retardation of gametogenesis ( Rahi & Shah, 2012 ).…”

Peer Review #1 of "Optimization of the cytogenetic protocol for Pangasianodon hypophthalmus (Sauvage, 1878) and Clarias gariepinus (Burchell, 1822) (v0.1)"

“…Chromosome preparation in post larvae fishes can be isolated from different tissues. These includes; fins (McPhail and Jones, 1966), gills (Yoo et al, 2017), scales (Ojima et al, 1972), kidney (Zhao et al, 2015Huang et al, 2017) abdominal cavity fluid (Fan and Fox, 1990), gonads (Tan et al, 2004) to mention but a few. Despite successfully chromosomes isolation from these tissues, variations in the mitotic cell division rates could result in differences in the quality and quantity of the chromosome observed (Shelton et al 1997).…”