The Regulation Mechanism Of Dio2/Dio3 System On Black-like Hamster Reproduction

The striped hamsters(Cricetulus barabensis)are the main pest of agricultural production in the northern area of China,it has large quantity,wide distribution,high fecundity,and Cricetulus barabensis is typical seasonal breeding animal,its reproduction peaked in spring and autumn,population fluctuations with seasonal characteristics,causing great distress to the agricultural production.Therefore,pest control is a problem which can’t be ignored in agricultural production.This topic is to study the candidate genes--Dio2(Type 2 iodothyronine deiodinase)and Dio3(Type 3 iodothyronine deiodinase),which are related to Cricetulus barabensis reproduction,and to understand Cricetulus barabensis reproductive mechanism and population seasonal outbreak mechanism in the molecular level.Dio2 and Dio3 belong to the deiodinase family,its main function is to regulate the dynamic balance of thyroid hormone(T2,T3,T4,rT3),thereby regulating the key genes related to reproduction GnRH.This study used the method of RT-PCR amplified and cloned the Cricetulus barabensis Dio2 and Dio3 cDNA sequence,and combined with the corresponding sequence of other closely related species to construct phylogenetic tree species.This study obtained the Cricetulus barabensis Dio2 cDNA 820 bp(GenBank accession number KJ667734),including complete CDS area 801 bp,Dio3 cDNA 934 bp(GenBank accession number KJ619382),including complete CDS area 915 bp.Dio2 encoding 266 amino acid residues,which contains two selenocysteine residues(Sec);Dio3 encoding 304 amino acid residues,which contains a selenocysteine residue.Using Clustal 2.0 software and MEGA 5.0 software to have multiple comparison analysis of Cricetulus barabensis Dio2 and Dio3 cDNA sequence with rats,mice,Mesocricetus auratus,horses,cows,human,and many other species corresponding cDNA sequence,and construct phylogenetic tree,have cluster analysis,the results show that the Cricetulus barabensis,Mesocricetus auratus and Phodopus sungorus have closest evolutionay relationship,and Rattus norvegicus and Mus musculus were closer,and several of other species such as Primates and Artiodactyla were farther,which is consistent with the traditional classification of species.Hereafter,Real-time fluorescent quantitative PCR method was used to detect the relative expression amount of Dio2 and Dio3 in different developmental stages,different seasons and different photoperiodic treatment of Cricetulus barabensis.Found in the developmental expression pattern exploration,Dio2 and Dio3 in male Cricetulus barabensis adulthood expression quantity highest,speculated that they play an important role in reproduction.Dio2 and Dio3 expressed the highest in female Cricetulus barabensis subadult quantity,indicating that Dio2 and Dio3 play an important role in the process of maturation in subadult.Expression of Dio2 and Dio3 have sexual and developmental stage specific.In exploration of seasonal reproduction,the expression quantity of Dio2 is higher in the spring and autumn,consistenting with the season expression pattern of GnRH,also consistenting with the research fact that Cricetulus barabensis,the breeding peak is in the spring and autumn.Therefore,Dio2 play a positive role in reproduction regulation of Cricetulus barabensis.In hypothalamus,the expression quantity of Dio3 is higher in the spring and autumn,while the expression quantity of Dio3 is higher in winter in testicles and ovaries.The expression of Dio3 in central nervous system and peripheral gonad is inconsistent,because Dio3 in the hypothalamus have been influenced greater by the photoperiod(12L:12N),while the efficient expression of Dio3 in winter shows that Dio3 inhibit the reproduction of Cricetulus barabensis in the gonads.On exploration of photoperiodic treatment,Dio2 was significantly higher in LD compared to SD and MD conditions.The results showed that Dio2 play a positive role in reproduction regulation of Cricetulus barabensis which is long sunshine breeding animals,and photoperiod has the synchronism function on the hypothalamus and gonads.In photoperiod treatment,the expression quantity of Dio3 in hypothalamus are highest in MD,and they have significant difference in MD compared to SD and LD conditions;but the expression quantity of Dio3 in Peripheral gonad are highest in SD.This suggests that what promote Dio3 express efficiently in the central nervous system is MD conditions(12L:12N),it is consistent with the illumination time of spring and autumn season,the same with seasonal expression;While the efficient expression of Dio3 in SD conditions shows that Dio3 inhibit the reproduction of Cricetulus barabensis in the gonads.This study analyzes the function of Dio2 and Dio3 in regulating Cricetulus barabensis reproduction,and its expression pattern affected by season,light cycle.The results provide not only a new way for understanding Cricetulus barabensis reproductive mechanism from the perspective of molecular biology,but also an effective way to control the rodent from a biological point.