Hybrid And Polyploid Inducement Of Rainbow Trout (Oncorhynchus Mykiss)

The crossbreeding between rainbow trout(Oncorhynchus mykiss)and brook trout (Salvelinus fontinalis)were carded out.About 200 four-month-old fingerlings were obtained from rainbow trout(♀)×brook trout(♂),but failed in rainbow trout(♂)×brook trout(♀).Morphological characters of rainbow trout,brook trout and hybrids F₁ grilse were measured;there were no morphological difference among them except of soft -pelvic-ray between rainbow trout and brook trout.When they matured (two-year-old or more than two-year-old),the characters of F₁ were identical to rainbow trout,but they were unlikeness to brook trout on color,fin,figure,maturation period and egg quality.Electrophoresis was used to the 8 isozymes and protein of muscle of rainbow trout,brook trout and hybrids F₁.The electrophoresis patterns ofα-GPD,LDH,PGM, MDH,IDH,and ME of hybrids F₁ were identical to the rainbow trout,but they were much different from brook trout,suggesting that the hybrids F₁ of rainbow trout(♀)×brook trout(♂)is a genogenesis type.Chromosome prepared to the eggs of tetraploid induced by heat shock and hydrostatic pressure at the embryo period.The ratio of tetraploid induced by heat shock was 5.6%,and the ratio was 22.8%by hydrostatic pressure.The highest tetraploid ratio was produced by hydrostatic pressure at 5 hour and 40 minutes after insemination,and the tetraploid ratio is 22.8%.15 tetraploid fish had been detected from 5458 fingerlings. triploid have been produced by hybriding tetraploid with diploid.Hybrids triploid(rainbow trout(♀)×brook trout(♂))was induced using heat shock.The survival of hybrids triploid at the eyed-stage and 4-month-old were higher than hybrids diploid.Chromosome preparing to the hybrids triploid,and the ratio of triploid was 93.3%.The major axis,nuclear major axis and nuclear volume of red blood cell of triploid were 19.9μm,9.2μm and 75.7μm³,the size of diploid were 14.9μm,6.9μm and 51.3μm³,the difference was significant between diploid and triploid.In hematology numerical value of rainbow trout,the RBC in triploid was extremely lower than diploid, but was much higher than diploid in MCV.In addition,the LYM,GRN,MID in the leukocyte of triploid was significant higher than in diploid(P＜0.05).The sperm characters of diploid and triploid have been detected by SEM.the volume of haploid sperm in diploid rainbow trout were 3.4～7.6μm.According to haploid sperm in diploid,the sperm of triploid could sort to three kinds:haploid(n), diploid(2n)and triploid(3n),the ratio of these three kind were 55.3%,34.2%and 10.5%.