Studies On The Relationship Between Differential Gene Expression In Ovary And Heterosis Of Reproduction Traits In Chicken

In order to understand the molecular basis of chicken heterosis in reproduction traits, mRNA differential display method and real time fluorescence quantify reverse transcriptional polymerase chain reaction (FQRT-PCR) were used to analyze the differential gene expression of ovary tissue between hybrids and their parental lines in a 4X4 diallel cross, involving 4 chicken breeds, which were White Plymouth Rock (E), CAU Brown (D), Silkies (C) and White Leghorn (A). (1) On the basis of DDRT-PCR technique we found that:Total of 331 differential displayed cDNA bands from 1161 were displayed in the 4x4 diallel cross combinations with 30 pairs of primers, which shows the differences of gene expression between hybrids and their parental lines were very obvious in quantity and quality. Seven types of differential expression patterns were found: Co-dominance expressed pattern (T1), Underexpression of parental fragements in hybrids (T2), Over-expression of parental fragements in hybrids (T3), Hybrid-absence expressed pattern (T4), Single parent-specific expressed pattern (T5), Dominant expression fragements of single parent in hybrids (T6), Hybrid-specific expressed pattern (T7).Correlation analysis indicated that there were significant correlation between the pattern of T3 and the heterosis percentage of egg number of 32- week and 42-week old (p<0.01), while there are negative significant correlation between the pattern of T7 and the heterosis percentage of egg number of 32-week and 42 week-old (P<0.01).Of 18 differential expressed sequences conirmed by rerverse Northern dot blot sequenced, one was in high homology with encoded mRNA sequences with known functions(e=0); Other 17 sequences, without homologous sequences by BLAST analysis, were new EST sequences. The sequence of differentially expressed CtPA-like had high similarity with human tissue type plasminogen activator (tPA) (e=0), which can induce ovulation. The differential expression of CtPA-like gene between hybrids (DE ED) and their parental pure breeds (EE> DD) was likely to the heterosis of egg number on 32-week-old and 42-week-old in DE and ED. These results showed the heterosis of reproduction traits were related to gene differential expression between chicken hybrids and their parents. ( 2 ) By using the technique of FQRT-PCR we found that:Differential expressed content of Follicle stimulating Hormone Receptor (FSHR) gene and Estrogen Receptor (ER) gene in 32-week-old ovary is significant between hybrids and their parental pure lines. The expressed content of FSHR gene in hybrids on 32-week-old of age positively correlated to their heterosis percentages of egg number on 32-week-old and 42-week-old respectively (p<0.05). The expressed content of ER gene in hybrids positively correlated with their heterosis percentages of 32-week old and 42-week-old egg number respectively (p<0.05). These results indicated the heterosis of egg number traits were related to the differential expression of FSHR gene and ER gene.