Additional file 1: Figure S1. Histochemical stainning of NP specimens in donors and rat NP tissues. (a) HE staining of the human NP tissues from the Grade II, Grade III, Grade IV and Grade V groups (scale bar: 250 μm). (b) HE and SO staining of rat NP tissues from Control and puncture groups cultured 0 day, 7 days and 14 days (scale bar: 500 μm). Figure S2. The expression of anabolic or catabolic genes of intervertebral disc and clock genes in rat NP cells. (a) The mRNA levels of Acan, Adamts5, Mmp3 and Mmp13 in Control and IL-1β group. (b) The mRNA levels of Per1, Per2, Cry1 and Cry2 in Control and IL-1β group. Figure S3. The efficiencies of knock down Bmal1 of NP cells by different si RNAs. (a) The efficiencies of knock down Bmal1 of NP cells by si RNAs were determined by qRT-PCR. n = 3, NS, not significant difference, *P