Bao and Xu BMC Genomics 2011, 12:224 http://www.biomedcentral.com/1471-2164/12/224 Page 6 of 14 Figure 3 Identification of differentially expressed transcripts. Total RNA was extracted from day 1–2 brains of diapause- and nondiapause- destined pupae. Expression of 12 transcripts selected from the F (A) and R libraries (B) was analyzed by RT-PCR, with actin as a control. Four transcripts from the F library (C) were measured by Northern blot analysis. N, nondiapause-destined individuals; D, diapause-destined individuals. The results are representative of two independent experiments. complex subunit 3 is a component of the sensor of ssDNA (SOSS) complex, which is required for efficient homologous recombination-dependent repair of double- strand breaks [14]. Signaling pathway Several signaling pathways are involved in the regulation of developmental arrest, such as the guanylyl cyclase pathway, TGFb-like pathway, insulin-like pathway, and steroid hormone pathway [15]. In this study, the tran- scription of the Akt gene (HarDP-C672) was up-regu- lated. Akt is an important protein in the insulin-like pathway (Table 1C). In contrast, calmodulin protein kinase II (CaMK II) (HarNP-1301) and arginine kinase (ArgK, HarNP-138) are down-regulated during diapause initiation. Calmodulin-dependent signaling is required for development, and CaMK II is a key member of this signaling pathway. ArgK is a phosphotransferase that catalyzes the reaction between L-arginine and ATP to produce L-phospho-arginine and ADP, and it functions in the regulation of ATP level, as creatine kinase in ver- tebrates [16]. Cell cycle Six transcripts down-regulated at diapause initiation were cell cycle regulators (Table 1D). Cyclin-dependent kinase (CDK) 8 (HarNP-668) is a member of the CDK family, which are important regulators of cell cycle pro- gression. CDK8 is also a coactivator involved in regu- lated gene transcription of nearly all RNA polymerase