Z. Zhao et Aj. Zera, Enzymological and radiotracer studies of lipid metabolism in the flight-capable and flightless morphs of the wing-polymorphic cricket, Gryllus firmus, J INSECT PH, 47(11), 2001, pp. 1337-1347
The flight-capable morph of the wing-polymorphic cricket, Gryllus firmus, e
xhibited significantly higher activities of each of five lipogenic enzymes
compared with the obligately flightless morph on a standard and a high-carb
ohydrate diet during early adulthood. Similarly, the rate of incorporation
of [C-14]-acetate into total lipid was higher in the flight-capable morph d
uring this time. By contrast, activities of lipogenic enzymes and rates of
lipid biosynthesis, in general, did not differ between morphs on a low nutr
ient diet during early adulthood. Differences in lipid biosynthesis account
for previously documented differences in lipid reserves between morphs on
some, but not all, diets. Results of the present and previous studies indic
ate that increased lipid biosynthesis in the flight capable morph on standa
rd and high-carbohydrate diets constitutes an. important adaptation for fli
ght (production of lipid flight fuel). Lipid biosynthesis is negatively cor
related with ovarian growth, and may be an important biochemical component
of the trade-off between flight capability and ovarian growth in G. firmus.
Morphs also differed in activities of three enzymes of lipid catabolism. H
owever, the extent to which variation in activities of these enzymes betwee
n morphs results in variation in lipid catabolism is unclear. Finally, the
flight-capable morph had a substantially higher activity of alanine aminotr
ansferase in the fat body. Amino acids may be utilized for lipid biosynthes
is or energy production to a greater degree in the dispersing morph compare
d with the oligately flightless morph. This study is the first to document
differences in intermediary metabolism that underlie adaptations of morphs
of a dispersal-polymorphic species for flight vs. egg production. (C) 2001
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