As due to apoptosis in the head region (Fig. 1H ). We then observed the AC shapes. Injection of 200 pg of mNanog slightly elongated the AC in the absence of Activin A treatment (Fig. 1K, L), but less so with Activin A treatment (Fig. 1M). This elongation was dependent on the dose of injected mNanog (Fig. 1O). On the other hand, elongation of AC by Activin A was suppressed by injection with mNanog (Fig. 1N, O). Indeed, RT-PCR MC-LR chemical information analysis of stage-18 AC revealed that mNanog injection decreased MedChemExpress AZ876 expression of mesoderm genes such as ms-actin [19] and Xbra [20] in Activin A-treated AC, whereas the expressions of notochord markers, chd and Xnot, were upregulated (Fig. 1P). Furthermore, injection of 200 pg of mNanog mRNA into the ventral hemispheres of 4-cell embryos induced a weak secondary axis formation (Fig. 1Q, R). This induced axis did not include a head structure with eye vesicles (Fig. 1S), suggesting that mNanog may function not as a positive regulator of canonical Wnt signaling like siamois (sia) [21], but instead as a BMP inhibitor like chd and truncated-type BMP receptor (tBR) [5,22]. Furthermore, HE staining of mNanog-injected tadpole revealed both neural structures and notochord (Fig. 1T, U). Together, these results raised the possibility that mNanog possesses dorsal mesoderminducing activity in Xenopus embryo.Fig. 2B) [28,29]. Dorsal marker gene expression was not induced by mNanogDCD (Fig. 2B, 1st?rd 
columns). Quantitative analysis of the mNanog mRNA also suggested that mNanog function in mesoderm induction requires dimerization of the mNanog protein (Fig. 2B). To examine the effect of mNanog on endogenous mesodermal gene expressions, we performed in situ hybridization. Endogenous chd expression was observed in the dorsal lip region (Fig. 2C, black arrow), and only the control lacZ injection did not affect chd expression (Fig. 2C, white arrow). When mNanog was injected into the ventral marginal zone, ectopic chd expression was obviously induced (Fig. 2D, white arrow), suggesting that mNanog can induce chd expression in embryo, confirming the RT-PCR analysis. Xbra expression was seen around the yolk plug in normal embryo (Fig. 2E), but was specifically inhibited in the mNanog-injected area (Fig. 2F, white arrow), suggesting that mNanog negatively regulates Xbra expression. These data also indicated that mNanog affects the endogenous expression of mesodermal genes in Xenopus embryo. To further profile the mechanism of mesoderm induction driven by mNanog, we next compared the expression of mesodermal marker genes between Activin A treatment and mNanog injection. AC from normal embryo did not express any mesodermal genes (Fig. 2G, lane 2), but following treatment with Activin A at the dose of 1?0 ng/ml, chd and gsc were expressed in a dosedependent manner (Fig. 2G, lane 6?). Xbra was also efficiently expressed following both 1 ng/ml and 10 ng/ml Activin A treatment (Fig. 2G, lane 6?). When mNanog was injected, gsc 12926553 and chd expressions gradually increased (Fig. 2G, lane 3?), as did Xbra expression, although the effect of mNanog injection on Xbra expression was less enhanced than that induced by Activin A treatment (Fig. 2G, 3rd column). Several mesodermal genes including chd are induced by overexpression of canonical Wnt signaling and Xnr genes [5,30]. We therefore examined the expression of early canonical Wnt signaling target genes in our system. There was no increased expression of sia and Xnr3, known targets of canonical Wnt signalin.As due to apoptosis in the head region (Fig. 1H ). We then observed the AC shapes. Injection of 200 pg of mNanog slightly elongated the AC in the absence of Activin A treatment (Fig. 1K, L), but less so with Activin A treatment (Fig. 1M). This elongation was dependent on the dose of injected mNanog (Fig. 1O). On the other hand, elongation of AC by Activin A was suppressed by injection with mNanog (Fig. 1N, O). Indeed, RT-PCR analysis of stage-18 AC revealed that mNanog injection decreased expression of mesoderm genes such as ms-actin [19] and Xbra [20] in Activin A-treated AC, whereas the expressions of notochord markers, chd and Xnot, were upregulated (Fig. 1P). Furthermore, injection of 200 pg of mNanog mRNA into the ventral hemispheres of 4-cell embryos induced a weak secondary axis formation (Fig. 1Q, R). This induced axis did not include a head structure with eye vesicles (Fig. 1S), suggesting that mNanog may function not as a positive regulator of canonical Wnt signaling like siamois (sia) [21], but instead as a BMP inhibitor like chd and truncated-type BMP receptor (tBR) [5,22]. Furthermore, HE staining of mNanog-injected tadpole revealed both neural structures and notochord (Fig. 1T, U). Together, these results raised the possibility that mNanog possesses dorsal mesoderminducing activity in Xenopus embryo.Fig. 2B) [28,29]. Dorsal marker gene expression was not induced by mNanogDCD (Fig. 2B, 1st?rd columns). Quantitative analysis of the mNanog mRNA also suggested that mNanog function in mesoderm induction requires dimerization of the mNanog protein (Fig. 2B). To examine the effect of mNanog on endogenous mesodermal gene expressions, we performed in situ hybridization. Endogenous chd expression was observed in the dorsal lip region (Fig. 2C, black arrow), and only the control lacZ injection did not affect chd expression (Fig. 2C, white arrow). When mNanog was injected into the ventral marginal zone, ectopic chd expression was obviously induced (Fig. 2D, white arrow), suggesting that mNanog can induce chd expression in embryo, confirming the RT-PCR analysis. Xbra expression was seen around the yolk plug in normal embryo (Fig. 2E), but was specifically inhibited in the mNanog-injected area (Fig. 2F, white arrow), suggesting that mNanog negatively regulates Xbra expression. These data also indicated that mNanog affects the endogenous expression of mesodermal genes in Xenopus embryo. To further profile the mechanism of mesoderm induction driven by mNanog, we next compared the expression of mesodermal marker genes between Activin A treatment and mNanog injection. AC from normal embryo did not express any mesodermal genes (Fig. 2G, lane 2), but following treatment with Activin A at the dose of 1?0 ng/ml, chd and gsc were expressed in a dosedependent manner (Fig. 2G, lane 6?). Xbra was also efficiently expressed following both 1 ng/ml and 10 ng/ml Activin A treatment (Fig. 2G, lane 6?). When mNanog was injected, gsc 12926553 and chd expressions gradually increased (Fig. 2G, lane 3?), as did Xbra expression, although the effect of mNanog injection on Xbra expression was less enhanced than that induced by Activin A treatment (Fig. 2G, 3rd column). Several mesodermal genes including chd are induced by overexpression of canonical Wnt signaling and Xnr genes [5,30]. We therefore examined the expression of early canonical Wnt signaling target genes in our system. There was no increased expression of sia and Xnr3, known targets of canonical Wnt signalin.