The Expression Characteristics Of Several Transcription Factors And The Expression Regulation On Monosaccharide Transporter GLUT2 In Small Intestine Of Chicken

Slow growth and low feed conversion rate is a common problem in local chicken breeds in China. The development of chicken intestine directly influenced the growth rate and feed conversion of chicken. The absorption of carbohydrate is the essential condition for the function of the tissues and organs in the process of the individual development. The absorption process is accomplished by the carbohydrate nutrition transporters. But when and how much the transporter gene expressed is regulated by multiple transcription factors. The aim of this study is to study the problem of nutrient absorption via the expression regulation profiles of intestinal nutrient transporters, to elucidate the molecular mechanism of nutrient absorption at the molecular level and provide the research basis for the breeding objective of chickens with high feed conversion rate.In the study,200 Arbor Acres broilers and 200 White Leghorn layers were chosen and were divided randomly into two groups, which were just hatching and had similar weight and normal development. A total of four groups for breeding:broiler fed with layer feed, broiler fed with chicken feed, legehenne fed with chicken feed and legehenne fed with layer feed. The body weight, the weight and length of small intestine of each test group at the day of 1、3、7、14 and 28, as well as the mRNA absolute expression levels of USFl and GATA3 were measured.In addition, carbohydrate transporter GLUT2 is the main vector for the delivery of glucose and fructose in small intestine. Its expression directly affects the absorption of carbohydrate nutrients in intestine. In order to study the expression and regulation mechanism of the transcription factor USFl, GATA3 and CDXA, which binding 5’upstream of gene GLUT2, the eukaryotic expression vectors pcDNA3.1-CDXA、pcDNA3.1-GATA3 and pcDNA3.1-USF1 and the method for cultivating the chick intestinal epithelial cells were established. To make genes USF1, GATA3 and CDXA over-expressed in cells of intestinal by means of transfection. Then, the absolute expression changes of GLUT1 in the transfected cells were tested by Real-time PCR. The results indicated that:(1) As the increase of age, the body weight, the weight and length of small intestine of Arbor Acres broilers and White Leghorn layers were growing, and the mRNA expressions of USF1 and GATA3 were significantly different (P< 0.01).(2) The body weight, the weight and length of small intestine of Arbor Acres broilers were higher than that of White Leghorn layers significantly (P<0.01). The effect of diet on chicken body weight at the age of 14 was significantly different (P<0.01), but on the weight of small intestine was different (P<0.05). The effect of diet on chicken body weight at the age of 7 was different (P<0.05), but on the weight and length of small intestine at the age of 28 was significantly different (P<0.01). The interaction effect between diet and breed on chicken body weight at the age of 14 was significantly different (P<0.01), on the weight of small intestine at the age of 3 was different (P<0.05), on he weight of small intestine at the age of 7 was significantly different (P<0.01), and on the length of small intestine at the age of 7 was different (P<0.05).(3) The related traits and USFl gene expression levels of Arbor Acres broilers and White Leghorn layers in different diets were not significant different (P>0.05), but the mRNA expression of GATA3 was different (P< 0.05). The interaction effect of diet and breed on the mRNA expression of USF1 at the age of 28 was different (P<0.05).(4) The interaction influence of diets and breeds on the growth traits and the mRNA expressions of USF1 and GATA3 of Arbor Acres broilers and White Leghorn layers was not significant different (P>0.05).(5) After the over-expression of gene USF1、CDXA and GATA3, the absolute expression changes of gene GLUT2 were tested by Real-time PCR. The results showed that, over-expression of transcription factor CDXA inhibited the expression of GLUT1 gene in IEC cells, over-expression of transcription factor USF1 and GATA3 play a positive regulation for the expression of GLUT2.In conclusion, this study provides some information for the regulation of gene expression in poultry nutrition and breeding research, and a theoretical basis to clarify the interaction mechanism of the related genes in the process of glycometabolism. Besides, the study establishes a research basis for cultivating excellent chicken breed with genetic characters of high feed conversion rate.