Effects Of Boron Concentration On Morpphology And Gene Expression Of Bursa Of Fabricius In Ostrich Chicks

African ostrich is the largest existing bird in the world.It has strong immunity,low feeding cost,fast growth and development,wide adaptability and high economic benefits.In the process of feeding,the first three months are the brooding period.Due to the influence of infection,disease and stress,the mortality of ostrich in brooding period is high,even up to 50%.Therefore,it is an urgent problem to reduce the mortality of ostrich in brooding period.The results showed that the high mortality of ostrich in brooding stage was closely related to the imperfect development of immune function.Bursa of Fabricius is a unique immune organ of birds.It is the place where B lymphocytes develop.The maintenance of its homeostasis is of great significance to the normal development of the immune system.A large number of studies have shown that boron is involved in the regulation of energy metabolism,brain function,immune function and bone health.However,there are few reports about the effect of Boron on bursa of Fabricius in African ostrich.Therefore,this project takes brooding ostrich as experimental animals,and compares the morphological structure and gene expression differences of bursa of Fabricius after adding different doses of boron in drinking water,so as to provide scientific basis for reasonable addition of boron in drinking water in ostrich breeding production.The main research work and results are as follows:1.The effects of different concentrations of boron on the growth performance of young ostrichIn order to compare the effects of different concentrations of Boron on ostriches,36 ostriches with similar body weight at 1 day old were randomly divided into three groups after adaptive feeding for 2 weeks: control group(0 mg / L),low dose group(80 mg / L)and high dose group(640 mg / L).After 90 days of feeding,fasting body weight was measured.The results showed that the body weight of low-dose group was significantly higher than that of high-dose group and control group(P < 0.05),and that of high-dose group was lower than that of control group,but the difference was not significant.The above results showed that low dose of boron could promote the growth and development of ostrich.2.The effect of different concentrations ofboron on the morphology of bursa of Fabricius of young ostrichIn order to compare the effects of different concentrations of Boron on bursa of Fabricius,paraffin sections were made and stained with he.The results showed that the cortical and medullary layers of bursa of Fabricius in low-dose group were obvious,the cells were closely arranged,the number of cells was large,the volume of cells was large,and the mucosal layer was thickened.In the high-dose group,there was no significant difference between the cortex and medulla of bursa Fabricius.The results showed that low-dose drinking water boron could promote the development of bursa of Fabricius in ostrich,while high-dose drinking water boron could inhibit the development of bursa of Fabricius in ostrich.3.the effect of different boron concentration on gene expression in Fabricius’ sac of ostrichIn order to compare the effect of boron concentration on gene expression in the bursa of ostrich,the gene expression difference in Fabricius sac was compared by transcriptional sequencing and Q-PCR.The results showed that 1449 genes were up regulated and 2017 genes were down regulated in the low dose group compared with the control group;1050 genes were up regulated and 2073 genes were down regulated in the high dose group.In the low dose group,bcl-2 homologous(bak),B-cell lymphama-2(Bcl-2),Fas associated factor-1(FAF1),Fas associated via death domain(FADD),Fas associated via death domain(FADD),Fas associated death domain(FADD),and Fas associated death domain(FADD)were found in the low dose group The results showed that the ECTODYSPLASIN a receptor(EDAR),myelocytsis regulator(Mcl-1),bcl-2-modifying factor(BMF),Rubicon autophagy regulator(rubcn),caspase recruitment domain containing protein 8(Card8).The six genes,Bak,Bcl-2,EDAR,FADD,FAF1 and Mcl-1,were identified by Q-PCR.The expression of Bak gene was significantly decreased in 80 mg/l group(P < 0.0001),bcl-2 increased significantly in 80 mg/l group(P < 0.001),EDAR decreased significantly in 80 mg/l(P < 0.01),and increased significantly in 640mg/l group(P <0.05);,FADD was significantly decreased in 80mg/l group(P < 0.0001),and increased significantly in 640mg/l group(P < 0.0001);FAF1 decreased significantly in 80 mg/l group(P < 0.01);Mcl-1 was significantly increased in 80 mg/l group(P > 0.05).The results of fluorescence quantitative analysis and sequencing showed that Bcl-2 and Mcl-1 were significantly increased in low dose group,significantly decreased in high dose group,and the pro apoptotic genes were opposite.The above studies showed that lowdose boron can inhibit apoptosis and high dose promote apoptosis.4.the effect of boron concentration on apoptosis and gene expression of Fabricius sac cells in young ostrichIn order to compare the effect of Boron on the apoptosis of ostrich bursa cells,TUNEL was used to detect the distribution of apoptosis cells in different groups,and the expression differences of apoptosis related proteins in the bursa were compared by immunohistochemistry.The results showed that the number of apoptosis cells in low dose group was significantly lower than that in control group(P < 0.01),while that in high dose group was significantly higher than that in control group(P < 0.05).Bak was significantly reduced in 80 mg/l group(P < 0.0001);Bcl-2 expression increased significantly in 80 mg/l group(P < 0.0001),and decreased significantly in 80 mg/l group(P < 0.001);EDAR decreased significantly in 80 mg/l group(P < 0.05)and increased significantly in 640mg/l(P < 0.05);FADD was significantly reduced in 80mg/l group(P < 0.01),and increased significantly in 640mg/l group(P < 0.05).The results show that low-dose boron can inhibit apoptosis and high-dose boron can promote apoptosis.In conclusion,adding low-dose boron in drinking water can significantly promote ostrich growth and development.The number of cells in bursa of farce is more,the cell arrangement in cortex is more compact,and the development is better than that of the control group.Bcl-2 and Mcl-1,which inhibit apoptosis,are significantly higher in m RNA and protein expression level than in the control group,and the expression of Bak,EDAR and FADD are significantly lower than that of the control group,Therefore,mitochondrial pathway is the main way of low-dose boron control apoptosis;There was no significant difference between the cortex and medulla in the high dose group.The number of cortical cells decreased and the development was inhibited.The apoptosis related genes EDAR and FADD increased significantly.Therefore,highdose boron promoted apoptosis through many ways.