Hemocyte marker proteins and regulation of the proPO system in a crustacean , Pacifastacus leniusculus

In crustaceans and other invertebrates, hemocytes are essential in immunity. The development of new hemocytes is important in the defence mechanisms in invertebrates. In crustaceans, new hemocytes which are synthesized in a specific organ called the hematopoietic tissue (Hpt). The hemocytes are produced and partly differentiated in the Hpt before they are released into the hemolymph and become freely circulating peripheral hemocytes. The final step of differentiation to mature hemocytes containing prophenoloxidase (proPO) takes place in the hemolymph. This paper presents the studies to identify proteins associated with development of different hemocyte types and a negative regulator of phenoloxidase-induced melanization in the freshwater crayfish Pacifastacus leniusculus. To obtain tools for more detailed investigations about the connection between semigranular cells, granular cells and precursor cells in Hpt of freshwater crayfish, Pacifastacus leniusculus and possibly also in other crustaceans, we have used two-dimensional gel electrophoresis (2-DE) coupled with matrix-assisted laser desorption/ ionization-time of flight (MALDI-TOF) mass spectrometry (MS) to identify specific proteins expressed in different hemocyte types differentially. In this study we report the specific expression of some genes in different hemocyte lineages and their transcript levels in Hpt cells in normal or previously laminarin or LPS treated animals analyzed by RT-PCR. Moreover, RNA inference experiments were also included to study the differentiation of Hpt cells. Söderhäll, K., Wu, C., Lin, X., Jiravanichpaisal, P. and Söderhäll, I. 2011. Hemocyte marker proteins and regulation of the proPO system in a crustacean Pacifastacus leniusculus, pp. 177-194. In Bondad-Reantaso, M.G., Jones, J.B., Corsin, F. and Aoki, T. (eds.). Diseases in Asian Aquaculture VII. Fish Health Section, Asian Fisheries Society, Selangor, Malaysia, 385 pp. Corresponding author: Kenneth.Soderhall, Kenneth.Soderhall@ebc.uu.se