Fig. 1. xMAK expression is dynamically regulated during Xenopus development. (A) The analysis of xMAK expression at different developmental stages. Total RNA from embryos isolated at different developmental stages was used for RT-PCR. FGFR served as a loading control. RT-, no reverse transcriptase. (B-M) Spatial distribution of xMAK RNA revealed by whole-mount in situ hybridization of albino embryos at indicated stages. (B-E,J,K) xMAK antisense probe. (F,G,I,L,M) xMAK sense probe. (D) Anterior view; e, eye; MHB, midbrain-hindbrain boundary. (H) En2 and Krox20 probes, anterior view. En2 is expressed as a bright band at the MHB, located anterior to Krox20, which marks rhombomeres 3 and 5. (B,F) Animal pole view; (C,G) lateral view; (E,I) dorsal view, anterior is towards the left. (J-M) Lateral view, anterior is towards the left. (K) e, eye; ov, otic vesicle; ba, branchial arches; tb, tailbud. (N,O) A cross-section of a stage 17 neurula embryo after in situ hybridization with xMAK antisense probe. Staining is observed in the deep (sensorial) layer of epidermal ectoderm (magnified view shown in O) and in somitogenic mesoderm.