Diapause-Related Gene Expression in Eggs of Multivoltine Bombyx mori L. Silkworm Races 195
that this enzyme might be utilized in fatty acid
β-oxidation as an energy source during embry-
onic development in B. mori.
Food Utilization
Only one gene related to food utilization was iso-
lated by SSH, i.e., taste receptor type 2 member.
The receptors of type II cells bind with sweet, bit-
ter, or umami compounds (Adler et al. 2000 ). The
actual function of the taste receptor type 2 mem-
ber during embryonic development in B. mori is
not clear.
Stress Response
In several insect species, heat shock proteins
are highly upregulated upon entry into diapause
(Denlinger et al. 2001). These proteins act as mo-
lecular chaperons by preventing abnormal pro-
tein folding during environmental stresses and
have also been implicated in playing a role in cell
cycle arrest (Feder et al. 1992 ). Hsp23 and hsp70
are upregulated during diapause in flesh fly Sar-
cophagi crassipalpis (Rinehart and Denlinger
2000 ). A small heat shock protein is observed to
be slightly upregulated during adult diapause in
Cx. pipiens (Robich et al. 2007 ). A heat shockFig. 2 Relative gene expression patterns of genes upregulated during non-diapause. RNA was isolated at 6 h intervals
from 6 to 48 h after oviposition. The experiment was performed in triplicate and results were standardized to the expres-
sion level of the constitutive β actin gene. A non-template control (NTC) sample was also run to detect contamination
if any. □-Non-diapause ■- Diapause