We previously cloned cDNAs for all the members (A, B and C) of Xenopus aldo
lase gene family, and using in vitro transcribed RNAs as references, perfor
med quantitative studies of the expression of three aldolase mRNAs in embry
os and adult tissues. A Xenopus egg contains ca. 60 pg aldolase A mRNA and
ca. 45 pg aldolase C mRNA, but contains only ca. 1.5 pg aldolase B mRNA. Th
e percent composition of three aldolase mRNAs (A:B:C) changes from 56:1.5:4
2.5 (fertilized egg) to 54:10:36 (gastrula), to 71:14.5:14.5 (neurula) and
to 73:20:7 (tadpole) during development. These results are compatible with
the previous results of zymogram analysis that aldolases A and C are the ma
jor aldolases in early embryos, whose development proceeds depending on yol
k as the only energy sourer. Aldolase B mRNA is expressed only late in deve
lopment in tissues such as pronephros, liver rudiment and proctodeum which
are necessary for the future dietary fructose metabolism, and the expressio
n pattern is consistent to that in adult tissues. We also show that three a
ldolase genes are localized on different chromosomes as single copy genes.
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