Exogenous hyalin and sea urchin gastrulation, Part II: hyalin, An interspecies cell adhesion molecule

摘要

The 330 kDa fibrillar glycoprotein hyalin is a well known component of the sea urchin embryoudextracellular hyaline layer. Only recently, the main component of hyalin, the hyalin repeat domain,udhas been identified in organisms as widely divergent as bacteria and humans using the GenBankuddatabase and therefore its possible function has garnered a great deal of interest. In the sea urchin,udhyalin serves as an adhesive substrate in the developing embryo and we have recently shown thatudexogenously added purified hyalin from Strongylocentrotus purpuratus embryos blocks a modeludcellular interaction in these embryos, archenteron elongation/attachment to the blastocoel roof. It isudimportant to demonstrate the generality of this result by observing if hyalin from one species of seaudurchin blocks archenteron elongation/attachment in another species. Here we show in three repeatedudexperiments, with 30 replicate samples for each condition, that the same concentration of S.udpurpuratus hyalin (57 ??g/ml) that blocked the interaction in living S. purpuratus embryos blockedudthe same interaction in living Lytechinus pictus embryos. These results correspond with the knownudcrossreactivity of antibody against S. purpuratus hyalin with L. pictus hyalin. We propose that hyalin???udhyalin receptor binding may mediate this adhesive interaction. The use of a microplate assay thatudallows precise quantification of developmental effects should help facilitate identification of theudfunction of hyalin in organisms as divergent as bacteria and humans.