The molecular mechanism of cell cycle arrest in the Bursa of Fabricius in chick exposed to Aflatoxin B 1 .

Aflatoxin B1 shows potent hepatotoxic, carcinogenic, genotoxic, immunotoxic potential in humans and many species of animals. The aim of this study was to clarify the underlying mechanism of G0 G1 phase and G2 M phase arrest of cell cycle in the bursa of Fabricius in broilers exposed to dietary AFB1 . 144 one-day-old healthy Cobb broilers were randomly divided into two groups and fed on control diet and 0.6 mg·Kg-1 AFB1 diet for 3 weeks. Histological observation showed that AFB1 induced the increase of nuclear debris and vacuoles in lymphoid follicle of BF. Results of flow cytometry studies showed that bursal cells arrested in G2 M phase at 7 days of age and blocked in G0 G1 phase at 14 and 21 days of age following exposure to AFB1 . The qRT-PCR analysis indicated that cell cycle arrested in G2 M phase via ATM-Chk2-cdc25-cyclin B/cdc2 pathway, and blocked in G0 G1 phase through ATM-Chk2-cdc25-cyclin D/CDK6 pathway and ATM-Chk2-p21-cyclin D/CDK6 route. In a word, our results provided new insights that AFB1 diet induced G2 M and G0 G1 phase blockage of BF cells in different periods, and different pathways were activated in different arrested cell cycle phase.