Storage hexamer utilization in Manduca sexta

Abstract

In preparing for metamorphosis insects store in their hemolymph and fat bodies a major nutrient reserve of 500-kDa hexamerins. At least three hexamerins serve this function in Lepidoptera, including arylphorin (ArH) and two high methionine proteins (M-MtH and V-MtH). Six day-old adults of Manduca sexta are shown here to have consumed over 99% of their pupal reserves of ArH and in the case of males, 99.8% of M- and V-MtH. In support of egg formation, however, females at this stage retain over 25% of their pupal reserves of the high methionine proteins. Demonstrated here are three factors contributing to the methionine protein reserves in day-6 adult females. (1) Pupal stores of the methionine proteins average 1.67 times larger in females than in males. (2) A fraction of this pupal store remains undiminished during pharate adult development: centrifugation of homogenates partitions the hexamerins into a fraction that is soluble in PBS and a smaller, particle-associated fraction that is not. Pharate adults consume most of the soluble fraction and relatively little of the particulate fraction, which then constitutes over half of the methionine protein reserves of post-eclosion females. (3) Both soluble and particle-associated reserves double in the week following eclosion and this suggests that adult females may resume the synthesis of V- and M-MtH. Though differing in amino acid sequence and antigenic properties, V-MtH and M-MtH showed no significant differences in their storage and utilization profiles.ArHarylphorinM-MtHmoderately high methionine hexamerinPBSphosphate buffered salineV-MtHvery high methionine hexamerinVgvitellogenin

The relationship between body mass and elemental composition in nymphs of the grasshopper Schistocerca americana

“…From an adaptive standpoint, the patterns of stoichiometric variation with body mass may be needed to fulfill the nutrients requirements of diapause, potentially increasing their fitness. According to our results and some published literatures (Tammaru et al 1996, Wheeler et al 2000, Rivero et al 2001, O'Brien et al 2002, Telfer and Pan 2003, Calvo and Molina 2005, we speculate that the high C:N in larval storage implies that holometabolous insects retain more lipid for survival. For the low C:N and C:S in larval storage, reflecting consumer sequestered more sulfur protein for metamorphosis and reproduction.…”

Expression and localization of storage protein 1 (SP1) in differentiated fat body tissues of red hairy caterpillar,Amsacta albistrigaWalker

“…During the larval pupal transformation, all storage proteins are taken up selectively by fat body tissue, albeit to varying degrees (Telfer and Kunkel, 1991). The SP1 showed fluctuation patterns similar to that reported in other insects Ryan et al, 1985;Kim et al, 1989;Pan and Telfer, 1996;Yoshiga et al, 1997;Telfer and Pan, 2003). N-terminal sequence data strongly suggest that all these proteins belong to the family of Met-rich hexameric storage protein or hexamerins (Telfer and Kunkel, 1991).…”

“…Storage proteins are major components of the hemolymph of the immature stage of insects and have been identified in a wide range of insect species, both hemi-and holometabolous (Levenbook, 1985;Kanost et al, 1990;Pan and Telfer, 2001). These proteins are important for insect development and, therefore, numerous studies concerning their structure, biosynthesis, regulation, and evolution have been conducted during recent years (Haunerland, 1996;Burmester 1999Burmester , 2001Telfer and Pan, 2003; Moreira et al, 2004, Ashfaq et Chandrasekar et al, 2007). Since the protein accumulates in dense protein granules, it was called SP, indicating its proposed function as an amino acid reserve for the production of adult proteins (Haunerland, 1996).…”

cDNA characterization and expression analysis of two arylphorin‐like hexameric protein genes from the diamondback moth, Plutella xylostella (L.)

“…In general, both arylphorin and methionine-rich proteins are considered sources of nitrogen and amino acids for post-prepupal stages, as, for example, production of oocytes and yolk proteins (Pan and Telfer, 2001;Telfer and Pan, 2003). Arylphorins are crucial as well in the synthesis of other somatic tissues, like adult integument (Pan and Telfer, 1996) and thus may be functionally di- vergent.…”