Changes in
expression patterns of stress protein genes during population growth of the
rotifer Brachionus plicatilis
G. Kaneko, S. Kinoshita, T. Yoshinaga, K.
Tsukamoto, S. Watabe-2002
Fisheries
Science, 68(6):
1317-1323
Abstract:
We amplified three kinds of cDNA fragments
encoding stress proteins from the rotifer Brachionus plicatilis by
polymerase chain reaction in order to investigate the molecular mechanisms
underlying mediation of its lifespan. The stress proteins were heat shock
protein 70 (HSP70), glucose regulated protein 94 (GRP94) and
ubiquitin-conjugating enzyme, which have been suggested to extend the
lifespans of fruitfly and yeast. The isolated clones consisted of 579, 776
and 257 bp in the above order, respectively, and their deduced amino
acid sequences showed 81, 59 and 48% identities, respectively, with
corresponding sequences from the nematode Caenorhabditis elegans. As
rotifers in the stationary phase can extend their lifespan we subsequently
performed northern blot analysis on rotifers both in the exponential and
stationary phases. The mRNA levels of HSP70 and GRP94 in the exponential
growth phase were 2.5 and 1.6 times higher, respectively, than those in the
stationary phase, whereas those of ubiquitin-conjugating enzyme did not
differ between rotifers in the two phases. These results suggest that stress
proteins are not directly responsible for the extension of rotifer lifespan,
but another factor(s) is possibly involved. Our results, however,
demonstrated that these genes are useful as molecular markers for monitoring
the population growth of rotifer.
(Laboratory of Aquatic Molecular Biology and
Biotechnology, Graduate School of Agricultural and Life Sciences, The
University of Tokyo, Bunkyo, Tokyo 113-8657, Japan, e-mail of S. Watanabe: awatabe@mail.ecc.u-tokyo.ac.jp)