Triploidy induction in Australian greenlip abalone Haliotis laevigata (Donovan) with cytochalasin B Yan Li 1,2 , Xiaoxu Li 2 & Jian G Qin 3 1 Dalian Fisheries University, Heishijiao, Dalian, China 2 South Australian Research and Development Institute (SARDI) Adelaide, SA, Australia 3 School of Biological Sciences, Flinders University, Adelaide, SA, Australia Correspondence: Y Li, School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide 5001, SA, Australia. E-mail: y.li@Flinders.edu.au Abstract Triploid induction in Australian greenlip abalone, Haliotis laevigata (Donovan), was conducted by block- ing the formation of the second polar body using cy- tochalasin B (CB). Twenty minutes after fertilization, the zygotes of greenlip abalone were treated with four CB concentrations (0, 0.25, 0.5 and 0.75 mg L 1 ) for 10, 15 and 20 min. The ploidy of resultant larvae was determined using £ow cytometry at 72-h post fertilization. Our study showed that fertilization, hatching, survival and induced triploidy of abalone larvae were signi¢cantly a¡ected by the CB concen- tration and treatment duration. The e¡ective range of CB concentration for triploid induction on greenlip abalone was 0.5^0.75 mg L 1 with an induction duration of 10^15min. The results indicate that the most e¡ective treatment combination for triploid in- duction in greenlip abalone is 0.5 mg CB L 1 for 15 min starting at 20-min post fertilization. Keywords: greenlip abalone, cytochalasin B, in- duced triploidy, £ow cytometry Introduction Australian greenlip abalone Haliotis laevigata (Dono- van) is a valuable seafood and has been widely cul- tured in Australia (Fleming 2000). Although the abalone aquaculture industry in Australia has bene- ¢ted from the development of a proper diet in the past decade, it is expected that genetic improvement (including chromosome manipulation) could further increase the growth potential (Li, Ponzoni, Brien, Nguyen & Butterworth 2005). Greenlip abalone is a slow-growing gastropod, and it normally takes 3 years to reach the market size of 80^100mm. This slow growth rate in abalone can be partially attribu- ted to the energy from somatic tissues to gonadal tis- sues (Liu, Heasman & Simpson 2004). Therefore, with the advantages of gigantism and sterility, triploi- dy is considered to be an e¡ective approach for abalone industry to reduce the production cycle, im- prove the product quality and also avoid genetic pol- lution in areas with high conservation interest (Fujino 1992; Elliott 2002). Over the last two decades, studies on triploidy in molluscan shell¢sh have mainly focused on bivalves, especially triploid oyster, which has been used for commercial production (Nell 2002). However, the triploidy induction in abalone is still at the experi- mental stage. Current methods for triploid induction in abalone include hydrostatic pressure (Curatolo & Wilkins 1995), thermal shock (Arai, Naito & Fujino 1986; Kudo, Arai & Fujino 1991; Yang, Chen & Ting 1998a), and chemical treatments with 6-dimethyla- minopurine (Zhang,Wang, Chang, Song, Ding,Wang & Wang 1998; Norris & Preston 2003) or cytochalasin B (CB) (Stepo & Cook 1998;Yang,Ting & Chen 1998b; Maldonado, Ibarra, Ramirez,Vazquez & Badillo 2001; Liu et al . 2004). Although CB has been reported as an e¡ective agent for triploid induction in bivalves (Allen Jr & Downing1986; Scarpa,Toro & Wada1994), recent stu- dies have shown that triploid induction with CB varies among species in abalone. Yang et al (1998b) found that a treatment with 0.25^0.5 mg CB L 1 for 10 min was su⁄cient to induce triploid in small Aquaculture Research, 2007, 38, 487^492 doi: 10.1111/j.1365-2109.2007.01689.x r 2007 The Authors Journal Compilation r 2007 Blackwell Publishing Ltd 487