DEVELOPMENT OF THE SYMBIOSIS OF CONVOLUTA ROSCOFFENSIS GRAFF AND PLATYMONAS SP.(1)

Area of Science:

• Symbiotic relationships
• Marine biology
• Cell biology

Background:

• The acoel flatworm Convoluta roscoffensis engages in a symbiotic relationship with the alga Platymonas sp.
• This symbiosis is crucial for the survival of C. roscoffensis, as it relies on the alga for nutrition.

Purpose of the Study:

• To investigate the morphological changes of Platymonas sp. algae within the acoel flatworm Convoluta roscoffensis.
• To understand the process of infection and the establishment of symbiosis between the two organisms.

Main Methods:

• Microscopic observation of infected C. roscoffensis.
• Analysis of algal morphology at different stages of infection.
• Investigation of potential enzymatic processes involved in algal transformation.

Main Results:

• Platymonas sp. algae lose flagella, theca, and eyespot sequentially after infecting C. roscoffensis.
• Algal flagellar basal bodies and striated rootlets persist within the host.
• Infected algae adopt an irregular shape with fingerlike processes that interface with host cells, a form potentially essential for mutualism.

Conclusions:

• The morphological alterations of Platymonas sp. are a critical adaptation for survival and function within C. roscoffensis.
• The loss of the theca may involve enzymatic dissolution, facilitating the intimate association between alga and host.
• The transformed algal morphology is a prerequisite for establishing a balanced photosynthetic mutualism.