SANTOS, N*; HOOPER, T; KIMBLE, M; St. Augustine College, Chicago; St. Augustine College, Chicago; Northeastern Illinois University: Cyanocytes in staged Limulus polyphemus trilobite larvae.

Hemocyanins are the primary oxygen transporting proteins in arthropods. In some species, hemocyanin is produced in glandular tissues and secreted into the hemolymph, while in others, including Limulus polyphemus, specialized cells (cyanocytes) are thought to be responsible for hemocyanin synthesis. Although the structure, composition and functions of L. polyphemus hemocyanin has been extensively studied, little is known about the location or origin of the cyanocytes, beyond Fahrenbach�s report of cyanocytes in the sinus spaces associated with the compound eyes. In a previous study, clusters of hemocyanin containing cells were identified in the coxal regions of each pair of legs in trilobite larvae (Kimble et al., 200X, in review). In this study, we have begun analyzing staged trilobite larvae to understand the dynamics of hemocyanin synthesis and accumulation in the newly hatched larvae. Preliminary results suggest that hemocyanin synthesis begins at about the time of hatching. Larvae fixed within 24 hrs of hatching have very few cyanocytes and the cells stain only weakly with the anti-hemocyanin antibody. By the fourth day post-hatching, the number of antibody positive cells has increased significantly and the individual cells stain more intensely. These results are consistent with a model in which the accumulation of both cyanocytes and hemocyanin is linked to the molting cycle, as has been observed in other arthropod species.