Study On The Variation Of Mitochondrial DNA Copy Number In Chicken

Mitochondria are the main sites in animal cell energy production,it's a Semi-autonomous organelles with independent genetic material mitochondrial DNA(mt DNA).The copy number of mitochondrial DNA reflects the abundance of intracellular mitochondria,and its number varies by age,organ and physiological conditions.However,how does the mt DNA copy number change during the growth and development of chickens? Is there any difference in mt DNA copy number between different sexes of chickens? So far there is no report about this,to this end,This study have selected three different sections and functional gene fragments of the mitochondrial genome(D-loop?ATP6?ND6)and nuclear single copy gene(GCG),and quantified the DNA copy number of chicken mitochondria by Taq Man fluorescence quantitative PCR.According to the different experimental animals,mainly from the following three parts of the experimental study.Trial 1 Temporal and Spatial Distribution of Mitochondrial DNA Copy Numberin Broiler ChickensA total of 5 chicks were randomly selected from the broiler chickens to study the tissue distribution characteristics of mitochondrial copy number of 12 tissues in 21-day-old broilers.On the basis of this,100 chickens were selected randomly for 1-day-old broilers.At the age of 1-day,21-day,42-day old and 60-day-old(take three mare 42-day-old broilers at the same time)and 11-embryo-age and 17-embryo-age,take the myocardium,liver,pectoral muscle,leg muscle tissue samples,to study the variation of mitochondria DNA copy number in different age and different sexes broiler chickens.The results show that:(1)There were significant differences in mt DNA copy numbers in different tissues of broilers(P<0.01).The number of mt DNA copies in brain cells was about 8200 copies,followed by myocardium,leg muscle,liver,pectoral muscle and testis And other organizations,and the blood mt DNA copy number at least 8.22 copies;(2)Before out of the shell,among the embryo age,the copy number of mt DNA had no significant difference(P>0.05);After hatching,different tissues mt DNA copy number showed different trends,myocardial,the mt DNA copy number in breast and leg muscle tissue increased with age(P<0.01),while the mt DNA copy number in liver gradually decreased(P<0.05).In each period,the copy number of mt DNA indifferent tissues has significant difference(P<0.01);(3)In different gender of 42-day-old broiler chicks,myocardium,liver,breast and leg muscle tissue mt DNA copy number in female was higher than that of male chicks,and the difference in liver reached significant level(P<0.05).The results show that in order to meet the energy needs of various tissues and organs,the mt DNA copy number of broiler chicken showed temporal and spatial specificity.Trial 2 Effects of Restricted Feeding on mt DNA Copy Number in BroilerTissuesA total of 84 male chicks were randomly divided into four groups(21 chickens per group): control group(ad libitum group),feed restriction group(fed with morning,afternoon fasting,hereinafter referred to as feed group),energy restriction group(15% energy restriction group.Hereinafter referred to energy group),protein restriction group(15% protein restriction group,hereinafter referred to as the protein group).The chicks were fed in different feeding methods in the early stage(8 to 21 days old).After 21 days of age,the chicks returned to normal nutrition and fed with free feeding.Samples of myocardium,liver,pectoral muscle and leg muscle were randomly selected three male broilers at 21 and 42 days of age.The aim was to study the effects of different feeding methods on the mt DNA copy number in broiler tissues.The results show that:(1)The feed restriction and energy restriction of 21-day-old broilers significantly decreased the body weight(P<0.05),and all the three kinds of feeding methods can reduce the mt DNA copy number in different tissues.The energy restriction and protein restriction significantly reduced the mt DNA copy number(P<0.05),while there was no significant effect on the number of mitochondrial copies in other tissues.(2)After three weeks of feeding(21d~42d)with normal nutritional condition,the body weight,breast muscle weight and leg muscle weight of early energy restriction group and protein restriction group broiler had no significant difference with the control group(P<0.05,well compensated);Restriction group broiler body weight and breast muscle weight was significantly lower than that of control group weight(P<0.05,incomplete compensation)of breast and leg muscle tissue copy number was significantly lower than the control group(P<0.05).Studies have shown that broiler by adjusting the tissue mt DNA copy number of tissue growth and metabolism on the early feeding adaptive adjustment,and have effect on the late growth performance.Trial 3 Differences in mt DNA copy number in different population of chickensA total of 52 Silkies(hereinafter referred to as silky)and Rhode Island Red hens were selected pure self propagation and reciprocal construction of the 4 F1 chicken resource populations(Rhode Island red×silky,silky×silky silky×Rhode Island red,Rhode Island red×Rhode Island Red).Conventional breeding to 60 days of age,each group choosed three chicks,and the 60-day-old broiler chicks were slected three,take myocardium,liver,breast and leg muscle tissue samples for analysis of different test in groups of chicken tissue mainly mt DNA copy number differences.The results are as follows:(1)In five chicken populations,except silk wool×Rhode Island Red Resources Group,other groups of mitochondrial copy number differences were significant difference(P<0.05),myocardial mt DNA copy is significantly higher than the liver and muscle copy number(P<0.05).(2)In Rhode Island red×silky resource group mt DNA copy number in all tissues was the highest,and in myocardial tissue,the reciprocal resource population silky×Rhode Island Red copy number of mt DNA was significantly lower than that of Rhode Island red×silky copy number(P<0.05);liver tissue in Rhode Island red×silky resource population mt DNA expression was significantly higher than the other group,the copy number of mt DNA(P<0.05);Rhode Island red×mt DNA silky muscle copy is significantly higher than the broilers(P<0.05).The results showed that there were significant differences in the mt DNA copy number of tissues in different population 60-day-old chickens.The Rhode Island red×silky resource group had the highest mt DNA copy number,and its tissue energy metabolism was the strongest.The growth and development of broilers were the fastest.