Ontogenetic changes in hemoglobin synthesis of two strains of Chironomus tentans.

Differentiating cells can be characterized by the number and types of proteins they produce (Markert, 1963). In man and other organisms the diversity of hemoglobins has been correlated with ontogenetic changes which reflect the alterations of gene activity (Ingram, 1963). Furthermore, the types of proteins produced are generally specific for the species. The study of insect coelomic proteins has followed closely that of mammalian serum protein analysis; however, profound differences exist between human blood and insect coelomic fluids. For this reason, the term 'hemolymph', rather than blood, has been used to designate these fluids. Svedberg & ErikssonQuensal (1934) first studied the ultracentrifuge properties of Chironomusplumosus hemoglobins and determined them to have a molecular weight of 34000. Braunitzer & Braun (1965) described the multiplicity of hemoglobins in Chironomus thummi and claimed two subunits per molecule. Man well (1966) suggested the hemoglobins of Chironomus plumosus possessed a monomeric structure. Thompson, Bleecker & English (1968) demonstrated the monomeric nature of Chironomus tentans hemoglobins and calculated a molecular weight of 15900 and suggested the hemoglobins were more asymmetrical than those of myoglobin. Unlike vertebrate hemoglobins, this insect protein is dissolved in the body fluids and constitutes over 90% of the proteinaceous material (Manwell,, 1966). Thompson & English (1966) have demonstrated the species-specific; patterns for several species of Chironomus and noted a general intensification of individual larval hemoglobins during the later stages of development. Manwell (1966) observed similar ontogenetic changes in small and large larvae of Chironomus plumosus. These differences in the sequential development of multiple hemoglobins suggested a ' switchover' in activity of certain hemoglobin genes. The following data give a more complete description of the ontogenetic changes in hemoglobin synthesis in Chironomus tentans and provide further evidence for the monomeric nature of this molecule. Such information may 1 Author's address: Department of Biology, Northern Arizona University, Flagstaff, Arizona, 86001.