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

Aflatoxin B 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 GG phase and GM phase arrest of cell cycle in the bursa of Fabricius in broilers exposed to dietary AFB. 144 one-day-old healthy Cobb broilers were randomly divided into two groups and fed on control diet and 0.6 mg·Kg AFB diet for 3 weeks. Histological observation showed that AFB induced the increase of nuclear debris and vacuoles in lymphoid follicle of BF. Results of flow cytometry studies showed that bursal cells arrested in GM phase at 7 days of age and blocked in GG phase at 14 and 21 days of age following exposure to AFB. The qRT-PCR analysis indicated that cell cycle arrested in GM phase via ATM-Chk2-cdc25-cyclin B/cdc2 pathway, and blocked in GG 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 AFB diet induced GM and GG phase blockage of BF cells in different periods, and different pathways were activated in different arrested cell cycle phase.