| The oryzias latipe is a small fish widely distributed in eastern Asia,southeastern Indochina Peninsula and Indonesian archipelago.It is characterized by its small size,abundant spawning and short breeding cycle.At the same time,it is widely used in developmental biology,toxicology and other research fields due to its advantages of easy observation of fertilization process,rapid embryo development and high sensitivity to water quality.The oryzias curvinotus(arched back medaka)is named for its raised arch-like shape when viewed from the outside.The oryzias curvinotus is a small fish that can live in wide temperature and salinity,tropical and subtropical zones,non-migratory upper estuaries.The team recently used molecular markers to reveal a clear genetic structure among the oryzias curvinotus population.In this study,the oryzias curvinotus of three different geographical groups in San Ya,Gao Qiao and Rao Ping were taken as the research objects.The hatching and early breeding methods of the oryzias curvinotus were optimized,and the morphological data of the three different geographical groups of oryzias curvinotus were measured.The transcriptomes of male and female glands in the San Ya population of oryzias curvinotus were analyzed,and the effects of temperature on the growth and development of the oryzias curvinotus in different geographic populations were explored,which provided theoretical guidance for the reproduction and resource protection of oryzias curvinotus.The relevant main results are as follows:I.The oryzias curvinotus used in this experiment were collected from San Ya(SY),Gao Qiao(GQ),and Rao Ping(RP),and the relevant parameters of each sampling point,such as annual average water temperature ans salinity,were recorded.It is showed that the annual average water temperature of the San Ya group was27.5 ?,which was significantly higher than that of the other two groups.Thesamples of three groups were used as parents to optimize the indoor hatching and early breeding methods of oryzias curvinotus.The average values of the spawning of the three groups in Rao Ping,Gao Qiao and San Ya were 23.88,22.64 and 24.64;The egg hatchability of the three groups in Rao Ping,Gao Qiao and San Ya were 87.04%,86.33% and 91.08%;And the survival rates of the three groups in Rao Ping,Gao Qiao and San Ya were 71.20%,81.36% and 88.52%.The sex-specific primers of oryzias curvinotus,Ocsex-F and Ocsex-R were used to identify the sex of the three groups.The results showed that two distinct DNA bands with length of 959 bp and 656 bp were amplified from the genetic male oryzias curvinotus in Gao Qiao and Rao Ping populations.In females,only a 959 bp band of DNA was amplified.In the San Ya population,only one 959 bp band of DNA was amplified in both male and female oryzias curvinotus.II.The morphological differences of 131 oryzias curvinotus in three populations(San Ya,Gao Qiao,and Rao Ping)were compared,and the fish eggs at the blastocyst stage were measured.There were significant differences with a P <0.001 between the horizontal and vertical diameters of the three groups and a result that Rao Ping> Gao Qiao> San Ya in terms of horizontal and vertical diameters.This study conducted a multivariate statistical analysis of the countable and quantitative traits of three populations of oryzias curvinotus(131 individuals):There were obvious male and female differentiation in body length / longest dorsal fin strip.Cluster analysis of the average value of 5 countable traits and 13 individual length / quantifiable traits indicated that Rao Ping and Gao Qiao were more similar in external morphology.The contribution rate of the first three principal component analysis was 68.14%,8.35% and 6.41%,respectively,and the cumulative contribution rate was 82.70%.Multivariate statistics showed that the differences between Rao Ping and San Ya groups were the largest,while Gao Qiao and Rao Ping groups were similar.By calculating the coefficients of variation of various indicators,it can be seen that the morphological differences among the three groups are the differences among different geographic populations within the species,which has not yet reached the level of subspecies.III.After analyzing the transcriptome of male and female glands in the San Ya population,21 genes were randomly selected to be verified by q RT-PCR.The results showed that although the fold changes were different,the overall trend of fold changes was consistent.The dmy gene(DM domain gene on Y chromosome)is asex-determining gene for oryzias curvinotus,while the dmy gene could not be retrieved in the male gonad transcriptome library of San Ya population,which was inconsistent with the fact that the other groups of male gonadal transcriptomes were available to obtain the dmy gene in the laboratory.This finding is of great significance to further explore the gender determination gene of oryzias curvinotus and to explore the gender determination and gender differentiation of oryzias curvinotus.IV.The egg membrane forming time of oryzias curvinotus at different temperature in Rao Ping,Gao Qiao and San Ya was calculated.In the range of22-30 ?,the egg membrane forming decreased with the temperature in the same population.At the same temperature,there were differences in the time of large amount of egg membrane forming in the three populations,which was San Ya> Gao Qiaoi> Rao Ping.When the zygotes of oryzias curvinotus were fertilized at a constant temperature of 22?,26? and 36?,it was found that: At 22 ?,the San Ya and Gao Qiao populations died a lot after 10 days later than group egg membrane forming,and very few(3 to 5%)could continue to grow.The Rao Ping population could grow after10 days,but the growth rate was slow.At a constant temperature of 26? and 30 ?,all three groups can grow normally,and the growth rate showed the trend of Rao Ping> Gao Qiao> San Ya. |
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