any,
Czech Republic)Comparison of methods for hatchery-scale triploidization of European catfish (Silurus glanis L.)
Journal
of Applied Ichthyology,17(6):247-255
Abstract:
Heat-, cold- and hydrostatic pressure shocks were
applied in order to improve triploidy induction in European catfish (Silurus
glanis L.). A 41°C heat shock (45 s, starting 9 min
after gamete activation) provided 88% triploids and a high percentage of
malformation (38.8 ± 4.1%). The superior 6°C cold shock (20 min,
starting 9 min after gamete activation) gave 100% triploids and a 33.4 ± 3.8%
triploid yield. The earliest hydrostatic treatments (600 kg cm2),
lasting 4 min and starting 3 min after gamete activation, gave
97.8 ± 1.8% triploids and a 33.7 ± 16.9% triploid
yield. The ploidy level was investigated using four approaches: karyotyping,
quantification of Ag-stained nucleoli per cell, flow cytometry, and
erythrocyte nuclear sizing by computer-assisted image analysis. Induction of
triploidy under mass conditions in three experiments gave triploid
percentages of 74%, 83% and 66%. Five months later, the percentage of
triploids significantly decreased to 12.4%, 8.2% and 21.4%. The growth
performance of yearlings was better in diploids than in triploids.
Differences between diploids and triploids were 13.5% (NS), 27.6% (P < 0.001)
and 25.4% (P < 0.05) in the three experiments. Analysis
of variance showed the influence of ploidy (P < 0.001)
on growth rate, and multiple range analysis (LSD) assessed differences
between total diploids (12.6 g) and total triploids (9.5 g) at the
P < 0.01 level.
(University of South Bohemia, Department of Fish Genetics and Breeding,
Research Institute of Fish Culture and Hydrobiology, Vod
any,
Czech Republic)