Biology Reference
In-Depth Information
wheat, SOPE interacts with the insect metabolic pathways involved in the biosynthesis of coenzyme
A and NAD
+
-FAD, which are the required cofactors for mitochondrial enzyme function. Moreover,
similar experiments had shown previously that adult aposymbiotic Þight ability was partly restored
when insects were supplemented with vitamins (Grenier
et al., 1994). This Ýnding links mitochon-
drial oxidative phosphorylation with Þight, an ATP-consuming phenomenon, and indicates that
SOPE interacts with both physiological traits and the behavior of weevils through Þight.
M
OLECULAR
I
NTERACTION
BETWEEN
SOPE
AND
W
EEVILS
Intracellular bacterial integration within the bacteriocytes has certainly evolved from prokaryotic
and eukaryotic gene Ñconversation.Ò The nature of these genetic communications is currently under
investigation in the weevil association, but several genes from other models have been studied in
terms of hostÏsymbiont interactions. Excluding microorganismÏplant associations, the marine
squidÏ
Vibrio
association is the best-studied animal model. The development of the squid light organ
requires the presence of the species-speciÝc bioluminescent bacterial symbiont,
Vibrio Ýscheri
(McFall-Ngai, 1998). This extracellular symbiont is recruited from the surrounding seawater by
the newly hatched squid (Ruby, 1996; Nyholm
et al., 2000). The establishment of the light organ
involves prokaryoticÏeukaryotic gene signaling that triggers many developmental changes such as
apoptosis, cell swelling, and oxidative stress (Foster
et al., 2000; Lemus and McFall-Ngai, 2000;
Visick
et al., 2000).
In the weevil symbiosis, the Ýrst evidence of gene interaction was provided by two-dimen-
sional electrophoresis experiments (Charles et al.
,
1997). Comparison between symbiotic and
aposymbiotic protein proÝles revealed at least four differential proteins Ð b, c, h- and e (
Figure
5.5)
.
! The protein b! is 30 kD and is expressed in the symbiotic strain only. Since it is not seen
on SOPE protein proÝles, it is likely to be expressed by the insect in the presence of SOPE
unless the protein is expressed by SOPE within the bacteriocyte and exported to the host cells.
The protein c (33 kD) is visualized speciÝcally in the aposymbiotic panel only. Its expression
could be related to either the absence of bacteria in aposymbiotic insects or the inhibition by
FIGURE 5.5
Two-dimensional
electrophoresis protein pattern of
S. oryzae
symbiotic strain (P1). Differences
observed in the aposymbiotic strain are reported in the panels P2, P3, and P4. b, c, h, and e proteins are represented
by 1, 2, 3, and 4, respectively. KDa = kilo Dalton; pHi = isoelectric pH. [ModiÝed from Charles, H., Heddi, A.,
Guillaud, J., Nardon, C., and Nardon, P. (1997).
Biochem. Biophys. Res. Commun
.
239:
769Ï774.]
