Gf. Zhang et al., Triploid induction in Pacific abalone Haliotis discus hannai Ino by 6-dimethylaminopurine and the performance of triploid juveniles, J SHELLFISH, 17(3), 1998, pp. 783-788
Pressure shock, thermal shock, and cytochalasin B treatment have been the m
ain treatments used in inducing triploid gastropod. In this study 6-dimethy
laminopurine (6-DMAP) was attempted to induce triploid in Pacific abalone,
Haliotis discus hannai Ino, by inhibiting formations of either polar body 1
(pb1) or polar body 2 (pb2). Although the highest triploid (73.5%) was obt
ained by blocking pb2 for 15 min with a 6-DMAP concentration as high as 300
mu M (the recommended dose for triploid induction in bivalve), no veligers
could survive. At the ranges of 75-150 mu M 6-DMAP, blacking pb2 for 20 mi
n resulted in higher abnormalities than blocking pb2 for 15 min. The relati
ve survival rate was higher and the abnormality was lower in the pb2 group
than those in the pbl group. No significant difference in triploid inductio
n (p > 0.05) was found both between 15- and 20-min treatments and between t
reatments targeting pb1 and pb2 at 75-150 mu M 6-DMAP. At 6-DMAP concentrat
ions of 75, 100, 125, and 150 mu M, in groups that blocked the ph 2 formati
on, the triploid yields (number of triploid larvae/fertilized eggs) were 30
.0, 46.0, 47.0, and 54.0% and the relative survivorships at the trochophore
stage were 96.8, 95.3, 94.8, and 90.5% for 15-min treatments, respectively
. The triploid yields were 30.1, 49.0, 51.2, and 56.0% and the relative sur
vivorships at the trochophore stage were 95.8, 90.2, 88.5, and 82.6% for 20
-min treatments, respectively; in groups that blocked pbl for 15 min, the t
riploid yields were 30.4, 43.0, 46.6, and 51.0% and the relative survivorsh
ips at the trochophore stage were 70.6, 68.4, 68.0, and 61.8%, respectively
. The shell dimensions of triploids and controls were measured at 4 mo post
fertilization. In the large-size group (1.2-1.3 cm), differences between 3n
and 2n groups in both dimensions and weight were significant (p < 0.01), w
hereas in the small-size group (0.7-0.8 cm), no significant differences wer
e found in dimensions (p > 0.05), but they were found in total weight (p <
0.01). Overall, the optimal treatment criteria for triploid production in P
acific abalone with 6-DMAP appear to be 125-150 mu M for 15-20 min at 500-6
00/mL zygote density and 23.0 degrees C.