Studies On Early Development And Genetic Characteristics Of Penglai Milky Sea Cucumber(Apostichopus Japonicus)

Penglai milky sea cucumber(Apostichopus japonicus)is a new line of sea cucumber ranching and aquaculture.It belongs to Apostichopus,Stichopodidae,Aspidochirotida,Holothuroidea,Echinodermata.Penglai milky sea cucumber came from Yantai Penglai.The wild resources are scarce,so Penglai milky sea cucumber has just got lots of aquaculture companies and institute's attention in recent years.With the maturity and development of trepang breeding technology,penglai milky sea cucumber' breeding technology is also making a breakthrough.As a consequence,the biology,genetics research of penglai milky sea cucumber needs to be addressed.In this paper,the study objects were penglai milky sea cucumber.Study the microscopic morphology of the early development process,the grey relational grade of each growth trait of different day-old,the methods of chromosomal preparation of different period embryonic and adult respiratory tree,in order to have a deeper understanding of the morphological characteristics,growth regulation,heredity characteristics,and provide theoretical foundation to reproduction and breeding of penglai milky sea cucumber.Part 1: The Morphological observation in the early development of Penglai milky sea cucumberIn this paper,for a better understanding and identifying the similarities and differences between Penglai milky sea cucumber and common sea cucumber,the spawning,fertilization,embryonic and larval development was described under the light microscope,and the time series table of embryonic and larval development was confirmed.As a result,at the water temperature of 19 ~ 21? and salinity of 31,the first and second meiosis were finished at 12 minutes and 24 minutes respectively after insemination;the egg develop to 2 cells at 1 hour;and the egg complete a cleavage every 30 minutes,develop to the blastula at 6 hours,19 hours to the gastrula;the fertilized egg grows into the early auricularia at 40 hours after fertilization;and then into the mid-auricularia and auricularia at 5 days and 8 days respectively.In addition,an irregular shaped calcareous bone appears at the end of posterior arm of the larva,and the water cavity and the calcareous bone on the same side.The larva metamorphosis develops to the doliolaria at 10 days,and the irregular bone develops into the gear bone,as well as appears the second calcareous bone.The larva develops into the pentactula at 12 days,14 days develops into the juvenile sea cucumber.There is no significant difference of the time series table between Penglai milky sea cucumber and apostichopus japonicus.Penglai milky sea cucumber is pure white on the whole body after juvenile.However,the common see cucumber appear some pigment at surface in 45 days,especially the bottom of parapodum.At 60 days,more than half of the juvenile is full of pigment.In a conclusion,Penglai milky sea cucumber is different from common sea cucumber for white body expressed stably in progeny.Penglai milky sea cucumber has got lots of aquaculture companies and institute's attention,this paper is a reliable theoretical basis for Penglai milky sea cucumber's research in the future.Part 2: Analysis on the growth traits of Penglai milky sea cucumberIn the paper,respectively take 112 day-old,142 day-old,206 day-old,262 day-old and 320 day-old Penglai milky sea cucumber,which was born on April 29,2015.Then use the concentration of 0.3 ~ 0.4 mol/L MgSO4 solution soaked them for 1 hour;select 20 completely unfold individual and measure the body length,number of parapodum,number of podia and body weight respectively.Then,take a grey relational analysis between main growth traits and ages,at the same time,the grey relational analysis between body length,number of number of parapodum,number of podia number and body weight.As a consequence,the grey relational degrees between each growth trait and ages were calculated and ranked as follows,number of podia(0.8219)were most closely correlate to ages,body weight(0.7772)and body length(0.7732)were more closely correlate to ages,number of parapodum(0.4655)were less closely correlate to ages.In the meantime,the grey relational degrees between each growth trait and body weight were calculated and ranked as follows,number of podia(0.8370)were most closely correlate to body weight,body length(0.7592)were more closely correlate to body weight,number of parapodum(0.4178)were less closely correlate to body weight.The conclusion: the number of podia were most closely correlate to ages and body weight of Penglai milky sea cucumber in 100 ~ 300 day-old.Number of podia is expected to be a new basic to estimate the age and genetic breeding of Penglai milky sea cucumber.Part 3: Study on chromosome of Penglai milky sea cucumberIn this paper,making a comparison the result of chromosomal preparation of different material(blastula,late-gastrula and respiratory tree)treated with different colchicine concentration(0.04%?0.06%?0.08%?0.1%)in different time(30 min,45 min,1h),and treated with different concentrations of hypotonic shock(0.075 mol/L KCl,0.0375 mol/L KCl).As a result,it is failed to access the chromosomes using blastula as experimental materials;it could acquire a good-shape medium-term chromosomes split phase by late-gastrula treated with 0.06% colchicine concentration in 1 h,and respiratory tree treated with 0.04% colchicine concentration in 45 min.Conclusion after analytic statistics,the number of chromosome of Penglai milky sea cucumber is 2n=46,as the same as apostichopus japonicas which previously reported.