Diapause-Related Gene Expression in Eggs of Multivoltine Bombyx mori L. Silkworm Races 197
sion which are characteristic of eukaryotes, and
is also frequently involved in the modulation of
gene expression in response to changes in the mi-
croenvironment of the cell.
Microarray Analysis
The gene expression profiles of diapause-induced
and non-diapause eggs of multivoltine silkworm
B. mori were investigated at 18 and 30 h after
oviposition using oligonucleotide microarrays
containing 24,924 probes. Data analysis revealed
upregulation of 638 genes and downregulation
of 1136 genes at 18 h after oviposition. At 30 h
after oviposition, 675 genes were upregulated
and 595 downregulated. Further, at 18 as well as
30 h after oviposition, 115 genes were stably up-
regulated, while 117 were stably downregulated.
The annotated genes showing fold change of one
and above were classified into seven functional
groups, viz., immune, metabolism, stress, signal
transduction, cell cycle, transcription, and apop-
tosis. Hierarchical clustering based on the Pear-
son coefficient correlation algorithm revealed
that most of the identified genes fall under the
transcriptional mechanism with an increase in
the number of genes expressed in diapause eggs
at 30 h compared to 18 h, but a decrease in the
case of non-diapause eggs. The overall genes ex-
pressed at 18 h was higher than that at 30 h under
both diapause and non-diapause conditions indi-
cating that crucial biological processes for ini-
tiation or termination of the diapause mechanism
occur during 18 h time period.
This work represents the first attempt at in-
vestigating the molecular aspects of embryonic
diapause in multivoltine silkworm eggs. Through
SSH, the differential regulation of diapause-relat-
ed genes in early embryonic diapause has been
demonstrated.
Acknowledgements This research work was supported
by grants from Department of Biotechnology, Ministry
of Science and Technology, Government of India (BT/
PR11397/PBD/19/192/2008 dated 30 June 2009).
References
Adler E, Hoon MA, Mueller KL, Chandrashekar J, Ryba
NJ, Zuker CS (2000) A novel family of mammalian
taste receptors. Cell 100:693–702
Bheda A, Shackelford J, Pagano JS (2009) Expression and
functional studies of ubiquitin C-terminal hydrolase
L1 regulated genes. PLoS One 4(8): e6764
Bobik TA, Havemann GD, Busch RJ, Williams DS,
Aldrich HC (1999) The propanediol utilization (pdu)
operon of Salmonella enterica serovar Typhimurium
LT2 includes genes necessary for formation of poly-
hedral organelles involved in coenzyme B (12)-depen-
dent 1, 2-propanediol degradation. J Bacteriol
181:5967–5975
Brown JJ (1980) Haemolymph protein reserves of dia-
pausing and nondiapausing codling moth larvae,
Cydia pomonella (L) (Lepidoptera: Tortricidae). J
Insect Physiol 26:487–495
Brown JJ, Chippendale GM (1978) Juvenile hormone
and a protein associated with the larval diapause of
the Southwestern Corn Borer, Diatraea grandiosella.
Insect Biochem 8:359–397
Clark AR, Docherty K (1993) Negative regulation of
transcription in eukaryotes. Biochem J 296:521–541
Craig TL, Denlinger DL (2000) Sequence and transcription
patterns of 60S ribosomal protein P0, a diapause-reg-
ulated AP endonuclease in the flesh fly, Sarcophaga
crassipalpis. Gene 255:381–388
Curtis D, Lehmann R, Zamore PD (1995) Translational
regulation in development. Cell 81:171–178
Danks HV (1987) Insect dormancy. An ecological per-
spective. Ottawa: Biological Survey of Canada (Ter-
restrial Arthropods), pp 439
Denlinger DL (2001) Time for a rest: programmed
diapause in insects. In: Storey KB (ed) Molecular
mechanisms of metabolic arrest: life in limbo. BIOS
Scientific Publishers Ltd, Oxford, pp 155–167
Denlinger DL (2002) Regulation of diapause. Annu Rev
Entomol 47:93–122
De Moor CT Richter JD (2001) Translational control
in vertebrate development. In: Etkin LD. Jeon KW
(ed) Cell lineage specification and patterning of the
embryo. Academic, San Diego
Feder JH, Rossi JM, Solomon J, Solomon N, Lindquist
S (1992) The consequences of expressing hsp70 in
Drosophila cells at normal temperatures. Genes Dev
6:1402–1413
Flannagan RD, Tammariello SP, Joplin KH, Cikra-Irland
RA, Yocum GD, Denlinger DL (1998) Diapause
specific gene expression in pupae of the flesh fly
Sarcophaga crassipalpis. Proc Natl Acad Sci U S A
95:5616–5620
Gonen H, Dickman D, Schwartz AL, Ciechanover A
(1996) Protein synthesis elongation factor EF-1a is an
isopeptidase essential for ubiquitin-dependent degra-
dation of certain proteolytic substrates. Adv Exp Med
Biol 389:209–219