| The color of animal is determined by the type and arrangement of pigment cells appearantly,but essentially depends on the genetic characteristics.Fish can be used as excellent models for studying of animal color for the colorful apperance.Myxocyprinus asiaticus is a rare fish in the Yangtze River.It has been developed into a new type of cultured fish in recent years and has important scientific and economic values.The body color of the fish changing at different age,which is different from most of the freshwater fish.We conducted this study for the purpose of exploring the patterns and genetic mechanisms of the color change of this fish.Firstly,we observed the types and distribution of the pigment cells in the scales.Secondly,the melanin-synthesis-related genes such as MC1 R,ASIP,tyrp1 and dct were cloned and the expression levlel in different tissues were compared.Finally,the RNA-seq was used for screening the color-related genes and signaling pathways of the fish.The main content and results were as follows:1.Four types of pigment cells were observed,named melanophores,erythrophores,xanthophores and iridophores,respectively.There have two cell forms been detected both in the melanophores and erythrophores,which were dendritic and blocky shapes.The body color of M.asiaticus was mainly determined by the shape and quantity of these two cells.The four pigment cells were all distributed in the fish’s scales with different development stages,but the distribution patterns were different.The pigment cells distributed non-stratified in the scales of juvenile fish,but stratified in the sub-adults and adult fish: the melanophores were mostly distributed in upper layer,while the erythrophores mainly distributed in the lower.The number of erythrophores was increased along with the growth of the fish.2.Among the melanin-synthesis-related genes of M.asiaticus,the c DNA of ASIP,MC1 R,tyrp1 and dct was 448,1356,1973 and 2407 bp in length,which encoded 127,325,528 and515 amino acids respectively.The results of RT-PCR showed that all the four genes were expressed in the skins of the juvenile and adult fish,but ASIP and tyrp1 expressed significantly different with age.The expression of ASIP in muscle of adult fish was significantly higher than that in juvenile fish.The expression of MC1 R in liver and pancreas of juvenile fish was significantly higher than that in adult fish.The tyrp1 and dct were highly expressed in the skin and eyes but lower in other organizations,moreover the two genes expressed significantly higher in eyes of juvenile fish than adult fish.3.A total of 47.44 GB raw data was obtained from skin transcriptomes of M.asiaticus,and 135,858 Unigenes were annotated into seven bioinformatic databases.Different expression analysis showed that there have 8310 differentially expressed genes between juvenile and adult fish,of which 6754 Unigenes were highly expressed in juvenile fish,and1556 Unigenes were highly expressed in adult fish.Twenty-four genes related to the color formation of the fish were screened out from DEGs,four(gsk3b,mib1,Erbb3 b and kita)of them highly expressed in adult fish,while twenty(tjp1a,ECE2,meox1,aldoaa,pdh B,Foxd3,rpe65 c,serpinf1,med23,neb,mybpc1,IGSF11,mical2 b,ASIP,adcy1 a,wnt5b,fgf6 a,mitf,EDNRB and camk2b1)genes highly expressed in juvenile fish. |
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