Adhesion between the archenteron tip and blastocoel roof in the NIH designated sea urchin embryo model is a cellular interaction that has interested investigators for over a century, but its molecular basis is not understood. Here we microdissect the two components of this cellular interaction and use alpha methyl mannose to map molecular groups that may be involved in mediating the cellular interaction. Whole 48–54 hour fixed Lytechinus pictus embryos were washed three times and then dissected in pH 8.0 artificial sea water (ASW), 15°C. The roofs of the blastocoel and the tips of the archenteron were put together and observed to stick together. In over 50 separate trials using bound sets of roof and archenterons attached together, either 0.2 M or 1.0 M alpha methyl mannose was added to the pieces. The pieces remained together. However in 100% of the cases, manually separating the pieces in alpha methyl mannose at either molarity resulted in blocking the rebinding of the blastocoel roofs and archenteron tips.Re‐binding occurred in the absence of the sugar. The results suggest that alpha methyl mannose binding receptors are involved in mediating the cellular interaction. These studies offer a novel approach to map glycans and glycan binding partners that may be functionally important. By microdissecting the components of cellular interactions out of the embryo proper, these components can be probed in pristine media away from factors in intact embryos that could confuse results (Supported by NIH NIGMS SCORE S0648680, MARC, RISE, the Joseph Drown Foundation, the Sidney Stern Memorial Trust, and CSU Northridge Biology Full Immersion Research Experience (FIRE) course funding).

Adhesion between the archenteron tip and blastocoel roof in the NIH designated sea urchin embryo model is a cellular interaction that has interested investigators for over a century, but its molecular basis is not understood. Here we microdissect the two components of this cellular interaction and use concanavalin A (Con A) and mannan derivatized agarose beads to map molecular groups that may be involved in mediating the cellular interaction. In over 50 separate trials, the results were either 100% binding or no binding, and indicated that Con A derivatized and mannan derivatized agarose beads bound to formaldehyde fixed dissected archenterons and roofs in both sterile distilled water (ddH2O) and pH 8.0 artificial sea water (ASW), 15°C, while 0.2 M alpha methyl mannose blocked the binding. Previous work indicated that fixed tissue displayed the same cell surface properties as live tissue. The results suggest that both Con A binding ligands and mannan binding partners are present on the two components of the cellular interaction. These studies offer a novel approach to map glycans and glycan binding partners that may be functionally important. By microdissecting the components of cellular interactions out of the embryo proper, these components can be probed in pristine media away from factors in intact embryos that could confuse results (Supported by NIH NIGMS SCORE S0648680, MARC, RISE, the Joseph Drown Foundation, the Sidney Stern Memorial Trust, and CSU Northridge Biology Full Immersion Research Experience (FIRE) course funding).

The adhesion between the NIH model sea urchin embryo roof of the blastocoel and tip of the archenteron is a cellular interaction that has interested investigators for over a century, yet its molecular basis is unknown. Here, 102 blastocoel roofs and archenterons were microdissected out of 102, 54 hr Lytechinus pictus embryos that adhered to each other when placed together. 25 mg per ml free mannan was added to the adhered roofs and archenterons. They remained adhered and then were pulled apart and placed together again in the free mannan solution. All 102 roofs and archenterons adhered once again, the mannan possibly bridging mannan‐binding receptors on both components. As reported in Part III of these studies, mannan conjugated agarose beads also adhered to the dissected roofs and archenterons and here this work was extended to 65, 54 hr L.pictus embryos. Part I of these studies indicated that alpha methyl mannose blocked the cellular interaction. Part II of these studies showed that mannose‐binding lectins could block the interaction. Taken together, this set of studies suggests that mannose‐containing glycans and mannose‐binding receptors may be involved in the cellular interaction between the archenteron and blastocoel roof. This microdissection method, that removes the components of adhesive events from intact embryos, is novel and likely to lead to a better understanding of the molecular basis of cellular interactions (supported by NIH NIGMS SCORE S0648680, MARC, RISE, the Joseph Drown Foundation, the Sidney Stern Memorial Trust, and CSU Northridge Biology FIRE course funding).