HISTOLOGY AND HISTOPATHOLOGY

Cellular and Molecular Biology

 

Effect of boric acid supplementation of ostrich water on the expression of Foxn1 in thymus

Ke Xiao1, Abdur Rahman Ansari1, Zia ur Rehman2, Haseeb Khaliq1, Hui Song1, Juan Tang1, Jing Wang1, Wei Wang1, Peng-Peng Sun1, Juming Zhong1,3 and Ke-Mei Peng1

1College of Veterinary Medicine, 2College of Animal Science, Huazhong Agricultural University, Wuhan, China and 3College of Veterinary Medicine, Auburn University, Auburn, AL, USA

Offprint requests to: Ke-Mei Peng, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070 China. e-mail: kemeip@163.com


Summary. Foxn1 is essential for thymus development. The relationship between boric acid and thymus development, optimal dose of boric acid in ostrich diets, and the effects of boric acid on the expression of Foxn1 were investigated in the present study. Thirty healthy ostriches were randomly divided into six groups: Group I, II, III, IV, V, VI, and supplemented with boric acid at the concentration of 0 mg/L, 40 mg/L, 80 mg/L, 160 mg/L, 320 mg/L, 640 mg/L, respectively. The histological changes in thymus were observed by HE staining, and the expression of Foxn1 analyzed by immunohistochemistry and western blot. TUNEL method was used to label the apoptotic cells. Ostrich Foxn1 was sequenced by Race method. The results were as following: Apoptosis in ostrich thymus was closely related with boric acid concentrations. Low boric acid concentration inhibited apoptosis in thymus, but high boric acid concentration promoted apoptosis. Foxn1-positive cells were mainly distributed in thymic medulla and rarely in cortex. Foxn1 is closely related to thymus growth and development. The nucleotide sequence and the encoded protein of Foxn1 were 2736 bases and 654 amino acids in length. It is highly conserved as compared with other species. These results demonstrated that the appropriate boric acid supplementation in water would produce positive effects on the growth development of ostrich thymus by promoting Foxn1 expression, especially at 80mg/L, and the microstructure of the thymus of ostrich fed 80 mg/L boric acid was well developed. The supplementation of high dose boron (>320mg/L) damaged the microstructure of thymus and inhibited the immune function by inhibiting Foxn1 expression, particularly at 640mg/L. The optimal dose of boric acid supplementation in ostrich diets is 80 mg/L boric acid. The genomic full-length of African ostrich Foxn1 was cloned for the first time in the study. Histol Histopathol
30, 1367-1378 (2015)

Key words: Foxn1, Thymus, Boric acid, African ostrich Chicks

DOI: 10.14670/HH-11-595