Localization of semaphorin 2a protein expression during development and in the adult of Limulus polyphemus

Christianna Allegra Howard, Tennessee State University


Semaphorins belong to a family of both membrane-bound and secreted proteins, all of which are characterized by an approximately 500 amino acid sequence called the SEMA domain. Semaphorins are grouped into eight classes based on similarities of domains and species of origin. Classes I and II are unique to invertebrates. Some semaphorins, including the invertebrate ones, have been postulated to play vital roles in axonal guidance. The objective of this study was to establish the expression pattern of invertebrate semaphorin 2a in the central nervous system of Limulus polyphemus (horseshoe crab). A Limulus-specific antibody was commercially generated against a 15 peptide region near the C-terminus of the near-full length clone of Limulus semaphorin and tested for specificity by Western blotting. Tissues were fixed in either paraformaldehyde or methanol and were either cryostat- or microtome-sectioned. Sections were processed using standard immunocytochemistry protocols. Sections were immunoreacted with the anti-semaphorin primary antibody. The antigen/antibody complex was visualized using an Alexa fluor secondary antibody. For control sections, the antibody was preabsorbed, denatured with heat, or substituted with PBS. Analysis by confocal microscopy revealed that semaphorin 2a is expressed in various regions of Limulus CNS. These data establish the expression pattern of semaphorin 2a in an invertebrate model and lay a foundation for further understanding the role(s) that semaphorin 2a play(s) in establishing and/or maintaining the architecture of the CNS.

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Recommended Citation

Christianna Allegra Howard, "Localization of semaphorin 2a protein expression during development and in the adult of Limulus polyphemus" (2007). ETD Collection for Tennessee State University. Paper AAI1447778.