Aldehyde dehydrogenases (ALDHs)
If retinoic acid (RA) is an endogenous regulator
of budding, RA synthase should be
active in the developing bud. RA is produced by oxidation
of retinal (retinaldehyde).
This reaction is catalyzed by aldehyde dehydrogenase
(ALDH).
Since many different types of aldehydes are produced
in a variety of metabolic
pathways, animals have many different types of ALDHs. The amino acid
sequence
of ALDHs is highly similar to one another so that substrates can hardly
be
predicted by the sequence. We therefore tried to
isolate ALDH cDNAs of which
mRNA expression was activated during bud development.
The figure shows the result of reverse transctiption-polymerase
chain reaction
(RT-PCR) analysis of three ALDHs. The amount of aldh-9
mRNA remained constant
during bud development, suggesting that this ALDH
is involved in the house-keeping
activities. The amount of aldh-P7 gradually
increased during bud development.
aldh-P18 mRNA was not detected in the adult
and the bud at the early stages.
The mRNA was strongly expressed in the 36 hour bud.
The next aim is to examine
whether these ALDHs can synthesize RA
Lane 1, adult; lane 2, 12 h-bud; lane 3, 24 h-bud; lane 4, 36 h-bud
References
Kawamura,K., Hara,K. & Fujiwara,S. (1993) Developmental
role of
endogenous retinoids in the determination of
morphallactic field in
budding tunicates. Development 117: 835-845.
Harafuji, N., Miyashita, S., Kawamura, K. & Fujiwara,
S. (1996) Molecular cloning
and expression of aldehyde dehydrogenases in the
budding ascidian
Polyandrocarpa misakiensis. Mem. Fac.
Sci. Kochi Univ. (Ser. D) 16/17: 7-16.