During their complex life cycle schistosomes alternate
between the use of stored glycogen and reliance on host
glucose to provide for their energy needs. In addition,
there is dramatic variation between the relative
contribution of aerobic versus anaerobic glucose metabolism
during development. We have cloned a set of
representative cDNAs that encode proteins involved in
glucose uptake, glycolysis, Kreb's cycle and oxidative
phosphorylation. The different cDNAs were used as
probes to examine the expression of glucose metabolism genes
during the schistosome life cycle. Steady state mRNA levels
from whole cercariae, isolated cercarial tails, schistosomula
and adult worms were analysed on Northern blots and dot blots
which were quantified using storage phosphor technology. These
studies reveal: (1) Transcripts encoding glycogen metabolic
enzymes are expressed to much higher levels in cercarial tails
than whole cercariae or schistosomula while the opposite pattern
is found for glucose transporters and hexokinase transcripts;
(2) Schistosomula contain low levels of transcripts
encoding respiratory enzymes but regain the capacity for aerobic
glucose metabolism as they mature to adulthood; (3) Male and
female adults contain similar levels of the different
transcripts involved in glucose metabolism.
