Mix; marginal zone
Mix (mesoderm induced homeobox), nucleic acid
Mix.1 cloned by Fred Rosa, 1989, and Mix.2 by Peter Vize, 1996. Very abundant mRNA, excellent marker of immediate-early response to mesoderm induction. Transcribed from MBT to stage 14. Expression is induced in animal caps by activin only. The probe used in B through E probably cross reacts with both Mix.1 and Mix.2. These genes are 89% identical at the nucleotide level (83% at amino acid level), and have similar, if not identical expression patterns as determined by RT-PCR analysis of dissected embryos.
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A. Lateral view of late blastula stained with Mix.1 (cleared). Photo by Richard Harland.
B. Section through Mix stained stage 9 embryo. Note both superficial and deep staining.
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C. Vegetal view of uncleared stage 9 embryo stained with Mix.
D. More lateral view of similar stage embryo.
E. Stage 10.5. The slightly lighter stain near the dorsal lip is probably due to mesoderm involution. Staining is difficult to detect in involuted mesoderm.
- Reference; Rosa,F.M.(1989) Mix.1, a homeobox mRNA inducible by mesoderm inducers, is expressed mostly in the presumptive endodermal cells of Xenopus embryos. Cell 57, 965-974. Note, title is a little missleading, expression is in both endoderm and mesoderm. In situs only really detect the mesodermal expression effectively in wholemounts.
Vize, P.D. (1996) DNA sequences mediating the transcriptional response of the Mix.2 homeobox gene to mesoderm induction. Developmental Biology, 177: 226-231.
- Clone; Mix2 cDNA, approx 1.2 kb, with BamHI ends.
- vector; Bluescript KSII+
- download Mix.1 sequence
- Download Mix.2 sequence
- Download Mix.2 promoter (activin responsive region) sequence
- Download graphical figure of Mix.2 promoter (.eps format)
- for Mix.2 sense transcripts cut with EcoRI and transcribe with T7
- for Mix.2 antisense transcripts cut with SacI or XbaI and transcribe with T3
- Mix2 available from Peter Vize
- Mix1 available from Fred Rosa.
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