Expression Of Brain Aromatase And Cytochrome Gene During The Early Gonadal Development Of Triploid Female Rainbow Trout

Rainbow trout(Oncorhynchus mykiss(Walbaum,1792))belongs to ray-finned fishes,salmon(Salmoniformes),salmon(Salmonidae)and salmon(Oncorhychus).Rainbow trout is a typical cold water fish with high protein no muscle between the thorn and meat characteristics of high rate.The meat of rainbow trout is rich in EPA DHA and unsaturated fatty acid.Rainbow trout is suitable for water resource enhancement and intensive cultivation.The gene Cyp19a1b?Cyp11a1?Cyp11b2?Cyp17a1?Hsd3b1 play an important role on steroidogenesis and gonadal differentiation of teleost,therefore in this study we chose from 31 to 68 dpf(days post fertilization)in the same cultured environment triploid and diploid rainbow trout(Oncorhynchus mykiss)as object.In this study triploid rainbow trout were used as object diploid rainbow trout were used as controls to research the expression of above several genes and the activity of CYP19A1 B enzyme in these brain of rainbow trout.Besides we also researched the form of rainbow trout's PGCs(primordial germ cells)in early stage.1.Expression of aromatase pathway gene in the different developmental stages of triploid female rainbow trout in early stageThe real-time PCR results showed that the expression of Cyp19a1 b in diploid rainbow trout was up-regulation during 30-50 dpf and maintained a stable level at this period,then during 50-56 dpf the expression was down-regulation after this during 56-68 dpf the expression was up-regulation again;the expression of Cyp19a1 b in triploid rainbow trout was up-regulation during 30-35 dpf down-regulation during 35-47 dpf,then during 47-55 dpf was up regulation again,after this until to 68 dpf the expression maintained a stable level.The expression of Cyp11a1 in diploid rainbow trout was reached peak value at 34 dpf,in triploid rainbow trout the peak value was appeared at 38 dpf.The expression of Cyp11a1 in triploid rainbow trout is later than that in diploid.After this stage the expression was downregulation,at 49 dpf the expression was reached to second peak.The expression of Hsd3b1 in diploid rainbow trout was maintained a higher level during 33-42 dpf and the expression was reached peak value at 38 dpf;the expression of Hsd3b1 in triploid rainbow trout was high during 47-59 dpf and reached peak value at 49 dpf.The expression of Cyp11b2 in diploid rainbow trout was reached peak value at 37 dpf and then the expression was downregulation,in triploid rainbow trout the peak value was appeared at 40 dpf and then the expression was down-regulation,but the expression of Cyp11b2 in triploid rainbow trout was lower than that of diploid at same period.The expression of Cyp17a1 in diploid rainbow trout was up-regulation at 35-46 dpf and the peak value was appeared at 45 dpf and then the expression was down-regulation until to 69 dpf,but in the same experimental conditions the expression of Cyp17a1 in triploid rainbow trout was not detected.2.Activity of brain aromatase in different developmental stages of diploid and triploid female rainbow troutIn the early stages of development the brain aromatase activity(CYP19A1B enzyme)of diploid and triploid female rainbow trout overall trend consistent.At 40 dpf the brain aromatase activity(CYP19A1B enzyme)of diploid and triploid female rainbow trout was reached to the peak together.But during 40 dpf-60 dpf,the activity of aromatase in diploid female rainbow trout was significantly higher than that in triploid female rainbow trout,especially at 45 and 50 dpf,the diploid activity of the enzyme was 1.15 times higher and 1.12 times higher than that of the triploid.At 62 dpf,the two curves crossed,the brain aromatase activity of diploid and triploid female rainbow trout decreased at the same time,and the difference of the enzyme activity was small.3.PGCs development of diploid and triploid female rainbow trout at different developmental stagesHE slices of the original germ cells of diploid and triploid 40,44 and 55 dpf were observed by 200 times of magnification under ordinary optical microscope.The cells were pear shaped,oval or round.There was an obvious boundary between the cytoplasm and nucleus.The nucleus was stained deeper and purplish red,and the cytoplasm was lighter,showing a colorless and transparent state.With the prolongation of development time,the number of primitive germ cells migrating to the reproductive crista in diploid and triploid was increased.The volume of the reproductive crista is also increased.But the diploid primordial germ cells were smaller than the triploid in the same period,the primordial germ cells migrating to the reproductive ridge in the triploid were less than of diploid.