Lectin histochemistry of the hyaline layer around the larvae of Patiriellaspecies (Asteroidea) with different developmental modes

Larvae of sea stars are surrounded by an extracellular matrix called the hy aline layer. The lectin-binding properties of this matrix were investigated in an ultrastructural study of Patiriella species having different modes o f development. The planktonic bipinnaria and brachiolaria of P. regularis a nd the planktonic brachiolaria of P. calcar demonstrated the same labeling of the hyaline layer for three lectins: Con A, SBA, and WGA. In both specie s the outer coarse meshwork stained for all three lectins, whereas the inte rvillous layer displayed patchy labeling. In the benthic brachiolaria of P. exigua, the outer coarse meshwork displayed heavy labeling for all three l ectins. The heavy labeling of the outer coarse meshwork of P. exigua compar ed with that of the other species suggests an increased number of lectin bi nding sites in the hyaline layer of this species. The similar ultrastructur e and histochemistry of the hyaline layer of P. regularis and P. calcar may reflect similar requirements of their extracellular cover in their plankto nic environment. Lectin labeling shows that hypertrophy of the hyaline laye r of P. exigua, in particular the outer coarse meshwork, involves elaborati on of the carbohydrate composition of the matrix. Modifications seen in the ultrastructure and histochemistry of the hyaline layer of P. exigua appear to be associated with the evolution of benthic development. (C) 1999 Wiley -Liss, Inc.