HATHAWAY, M.J.*; LI, S.*; DING, X.*; HATLE, J.D.*; BORST, D.W.; Illinois State Universtiy: Molecular Characterization of Hemolymph Storage Proteins in the Lubber Grasshopper

In many insects, storage proteins (SP) provide an amino acid reserve that can be used during metamorphosis and reproduction. In the lubber grasshopper, Romalea microptera, there are three abundant hemolymph proteins (~500kDa, ~200kDa, and ~90kDa) that rise and then decline during the oviposition cycle suggesting they function as storage proteins to support oocyte development. To test the hypothesis that these proteins are related to other insect storage proteins, each protein was purified and their trypsin fragments sequenced by LC-MS. The amino acid sequences of these fragments were used to design degenerate primers, which were then used to amplify a cDNA fragment for each protein. 5� and 3� RACE were used to obtain the complete cDNA sequence for the 90kDa protein (2,140bp), and partial sequences for the 500kDa protein (~1,160bp) and the 200kDa protein (~1,625bp). The deduced amino acid sequences of the three proteins are similar. Thus, the 90kDa protein is 46% and 38% similar to the 200kDa and 500 kDa proteins, respectively. The deduced sequences are also similar to many insect hexamerin storage proteins. For example, the 500kDa protein has 40% identity to the hexamerin precursor of Blaberus discoidalis, 32% identity to the juvenile hormone binding protein (JHBP) of Locusta migratoria, and 32% identity to the arylphorin-like hexamerin of Apriona germari. Analogous to other insect hexamerin storage proteins, the mRNAs for these three proteins are also detected in the lubber fat body by Northern blot analysis. We are currently studying the expression patterns of these three proteins during the reproduction cycle, as well as the effects of nutrition on their expression. Supported by NSF grants 9978810 and 0240903 to DWB.