Comparative analysis of proteome maps of silkworm hemolymph during different developmental stages

Two-dimensional polyacrylamide gel electrophoresis showed that from the larval to moth stages, silkworm hemolymph proteins changed markedly. Not only did major proteins such as SP1, SP2, and the 30 K lipoprotein change, but other proteins varied greatly at different stages. To understand the functions of these proteins in silkworm development, 56 spots were excised from gels for analysis by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). We identified 34 proteins involved in metamorphosis, programmed cell death, food digestion, metabolism, and nutrient storage and transport. Most proteins showed different expression at different stages, suggesting functions in development and metamorphosis. An abundance of proteins related to immunity were found, including hemolin, prophenoloxidase, serine proteinase-like protein, paralytic peptide-binding protein, and protease inhibitor.Proteomics research not only provides the opportunity for direct investigation of protein expression patterns, but also identifies many attractive candidates for further study. Two-dimensional maps of hemolymph proteins expressed during the growth and metamorphosis of the silkworm offer important insights into hemolymph function and insect metamorphosis.The mulberry silkworm, Bombyx mori, has been raised for more than 5000 years in Asian countries, and is a major economic resource for many families. Currently, the silkworm is not only a domesticated insect used for silk production, but is also a model lepidopteran for pest control studies. The silkworm has an open circulatory system containing hemolymph, which surrounds the tissues of the silkworm with blood. Nutrients and oxygen are delivered to all parts of the silkworm body through the hemolymph, which is also an important depository for nutrition and energy. After eating, the percentage of hemolymph in the silkworm increases as a proportion of body weight, while a silkworm that is starved or has just