Vertebrate Development Maternal to Zygotic Control (Advances in Experimental Medicine and Biology)

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Xenopus

Yanai et al. used custom microarrays to compare the temporal profiles for gene
expression in X. laevis and X. tropicalis (Yanai et al. 2011 ). While they were not
focused on gene expression changes during cleavage stages, they found multiple
genes that increase in abundance from the 2-cell stage to stage 8 (MBT is at stage
8.5), which likely includes pre-MBT transcripts. Although a caveat of this analysis
is that differences in signal could reflect changes in polyadenylation rather than
zygotic transcription (see below), they observe in both X. tropicalis and X. laevis an
increase at stage 8 in the VegT-regulated pre-MBT genes identified by Skirkanich
et al., consistent with a conserved mode of regulation for these pre-MBT genes.
Subsequent RNA-Seq analyses using more detailed temporal analysis of multi-
ple stages throughout cleavage stage development revealed additional type II
zygotic genes transcribed before the MBT in X. tropicalis. Collart et al. used both
oligo-dT primed and ribosome depleted RNA for libraries, and collected samples at
30 min intervals. They identified 960 RNAs that increased in apparent abundance

Egg 16-cell 64c 256c 1024c MBT St9 St10 St12

8 7 6 5 4 3 2 1

miR427 expression 0

(Log

10 )

miR-427 expression in Xenopus

miR-430 expression in zebrafish

32-cell 64-cell 128-cell 256-cell 512-cell

+ - + - + - + - + - RT

pri-mir430

pri-mir19a

a

b

Fig. 9.3 Zygotic expression of miR-427/430 during cleavage stage in Xenopus and zebrafish. (a)
Real-time RT-PCR analysis of pri-mir-427 at the indicated stages in Xenopus laevis. Data courtesy
of Dr. Jing Yang, University of Illinois, Urbana-Champagne. Pre-MBT expression of mir-427 was
first detected by Northern blot as shown by Lund et al. ( 2009 ). (b) RT-PCR analysis of pri-mir-430
and pri-mir-19a at the indicated stages in zebrafish, from Heyn et al. ( 2014 ) Supplemental data
(Fig. S4C), reprinted with permission from the authors and from Cell Press. “+” and “−” indicate
reaction products with and without reverse transcriptase (RT), respectively

M. Zhang et al.