Fluorescent antibody localization of Microciona prolifera aggregation factor and its baseplate component

Area of Science:

• Marine Biology
• Cellular Biology
• Biochemistry

Background:

• Marine sponges possess complex mechanisms for cell adhesion and aggregation.
• Aggregation factor (AF) and its receptor, baseplate (BP), are key components in sponge cell reaggregation.
• Understanding the localization and regulation of AF and BP is crucial for deciphering sponge cell interactions.

Purpose of the Study:

• To generate specific antibodies against Microciona prolifera aggregation factor (AF) and baseplate (BP).
• To determine the surface localization of AF and BP on disaggregated sponge cells.
• To investigate the role of divalent cations (Ca++ and Mg++) in maintaining AF and BP cell surface presence.

Main Methods:

• Production of specific rabbit antisera against purified AF and BP from Microciona prolifera.
• Indirect immunofluorescence assay using fluorescent-labeled goat anti-rabbit IgG to visualize AF and BP.
• Rotation-mediated assay to confirm antibody specificity and study the cation-dependent nature of cell aggregation.

Main Results:

• Specific antibodies confirmed the presence of both AF and BP on the surface of disaggregated sponge cells.
• AF and BP were detected on cell surfaces only in the presence of Ca++ and Mg++; they were absent in cation-free seawater.
• AF and BP showed differential distribution, being abundant on archeocytes and choanocytes but less so on gray cells.

Conclusions:

• This study validates the surface localization of aggregation factor and baseplate in Microciona prolifera.
• The cell-surface presence of AF and BP is dependent on divalent cations, highlighting their role in cell adhesion.
• The findings provide insights into the specific roles of different cell types in sponge aggregation processes.