The metabolic basis of life history variation: genetic and phenotypic differences in lipid reserves among life history morphs of the wing-polymorphic cricket, Gryllus firmus

Intermediary Metabolism and Life‐History Trade‐Offs: Differential Metabolism of Amino Acids Underlies the Dispersal‐Reproduction Trade‐Off in a Wing‐Polymorphic Cricket

“…The fat-free cricket residue was washed twice with 10% trichloroacetic acid, which removed unincorporated 14 C-glycine and radiolabel from glycine incorporated into soluble carbohydrate and other amino acids. The protein residue contained no detectable carbohydrate, as determined by the anthrone assay (Zera and Larsen 2001), and was solubilized by addition of 0.5 mL of 60% perchloric acid and 1 mL of hydrogen peroxide, followed by incubation at 70Њ-80ЊC for 1 h. Incorporation of glycine into carbohydrate was not measured because carbohydrate levels are low in morphs of G. firmus and do not appear to contribute significantly to the trade-off between early-age reproduction and flight capability (Zera and Larsen 2001).…”

The hemolymph JH titer exhibits a large-amplitude, morph-dependent, diurnal cycle in the wing-polymorphic cricket, Gryllus firmus

“…Crickets were reared under a 16:8 L:D cycle at 28 °C and were fed the standard diet described in Zera and Larsen (2001). Other details of rearing can be found in Zera and Cisper (2001).…”

Biochemical basis of specialization for dispersal vs. reproduction in a wing-polymorphic cricket: Morph-specific metabolism of amino acids

“…These diets are known to affect whole-body mass gain, ovarian growth, lipid accumulation, and many aspects of lipid metabolism in morphs of Gryllus (Zera et al, 1998;Zera and Larsen, 2001;Zhao, 2003a andZhao, 2003b). C-1 crickets were raised on the high nutrient (100%) diet from egg hatch until molt to adulthood (day 0), after which they were either maintained on that diet, or switched to one of the other two diets; C-2 crickets were always fed the standard 100% diet.…”

“…Standard chemical extraction protocols, thin-layer chromatography, and liquid scintillation counting (see Zera and Zhao (2006) for details) were used to quantify the amount of radiolabel incorporated during a 5 h incubation period (28° C) into the following chemical components: expired CO 2 (trapped in aqueous NaOH contained in a cup near the top of the sealed fl ask); ovarian and somatic (whole-body minus ovaries) total protein; and somatic and ovarian total lipid, triglyceride and phospholipid. Incorporation of 14 C from glycine into carbohydrate was not measured because carbohydrate levels are low in morphs of G. fi rmus and do not appear to contribute signifi cantly to the trade-off between early age reproduction and fl ight capability (Zera and Larsen, 2001). …”

“…A number of physiological studies have documented differences between morphs in energetic or endocrine aspects of fl ight capability and egg production (reviewed in Zera and Denno, 1997;Zera et al, 1998;Zera and Harshman, 2001, Zera, 2004, Zera, 2005. More recently studies in the wing-polymorphic cricket, Gryllus fi rmus, have begun to investigate the biochemical basis of morph specialization for dispersal vs. reproduction, most notably the role of morph-specifi c differences in lipid metabolism (Zhao and Zera, 2002;Zera and Zhao, 2003a, Zera and Zhao, 2003b, Zera and Zhao, 2004As is the case for many other insects, especially orthopterans (Beenakkers et al, 1985;Candy, 1989), the fl ight-capable morph of G. fi rmus accumulates substantially more total lipid and triglyceride, than its fl ight-capable counterpart during the fi rst week of adulthood (Zera and Larsen, 2001). Subsequent biochemical studies have shown that the increased lipid (triglyceride) levels in the dispersing morph are produced by elevated de novo biosynthesis of fatty acids, increased diversion of fatty acids into triglyceride as opposed to phospholipid biosynthesis, and decreased oxidation of fatty acids relative to the fl ightless morph (Zhao and Zera, 2002;Zhao, 2003a andZhao, 2003b;Zera, 2005).…”