Terminal alpha-d-mannosides are critical during sea urchin gastrulation

Area of Science:

• Developmental Biology
• Glycobiology
• Cell Biology

Background:

• Sea urchin embryos are a model system for studying human health and disease mechanisms.
• High-mannose glycans and polysaccharides play roles in biological processes, including embryonic development.

Purpose of the Study:

• To investigate the role of high-mannose glycans in sea urchin (Lytechinus pictus) gastrulation.
• To determine the effect of α-mannosidase enzyme on embryonic morphology and cell adhesion.

Main Methods:

• Incubation of Lytechinus pictus embryos with Jack bean α-mannosidase.
• Observation of morphological deformations in living embryos.
• Microdissection of fixed embryos to assess archenteron-blastocoel roof adhesion in vitro.

Main Results:

• Enzyme treatment induced significant morphological deformations in developing embryos.
• Even low enzyme activity (0.06 U/ml) caused developmental abnormalities.
• α-mannosidase treatment abrogated the in vitro adhesion of the archenteron tip to the blastocoel roof.

Conclusions:

• Terminal mannose residues are essential for normal gastrulation in sea urchin embryos.
• These residues are involved in the adhesion between the archenteron and blastocoel roof.
• This adhesion may involve a lectin-like mechanism potentially unaffected by fixation.