Algae permeability to Me(2)SO from -3 to 23 degrees C

Area of Science:

• Cellular and Molecular Biology
• Biophysics
• Cryobiology

Background:

• Cryoprotective agents (CPAs) are crucial for preserving biological cells at low temperatures.
• Understanding solute and water transport dynamics is essential for optimizing cryopreservation protocols.
• Algal cells, like Chlorococcum (C.) texanum, offer a model system to study these transport phenomena.

Purpose of the Study:

• To quantify the biphasic transport of water and dimethyl sulfoxide (Me(2)SO) in C. texanum cells.
• To determine the temperature-dependent permeability of algal cells to water and Me(2)SO.
• To compare the transport characteristics of Me(2)SO with methanol (MeOH) as CPAs.

Main Methods:

• A two-step experimental protocol using a cryoperfusion stage to induce and measure cell volume changes.
• Exposure to impermeable (sucrose) and permeable (Me(2)SO, MeOH) solutes at varying temperatures (-3 to 23°C).
• Computer analysis of video images to determine cell volumes and fitting a network thermodynamic model to transient data.

Main Results:

• Biphasic transport of water and Me(2)SO was observed, with transport rates decreasing at colder temperatures.
• Water entered C. texanum cells faster than Me(2)SO.
• Methanol (MeOH) permeability was significantly higher (at least three orders of magnitude) than Me(2)SO permeability, with this difference widening at lower temperatures.

Conclusions:

• The study elucidates the differential permeability of algal cells to various CPAs, highlighting Me(2)SO's slower transport compared to water and MeOH.
• Findings provide critical data for developing more effective cryopreservation strategies for algal cells.
• Temperature significantly impacts the kinetics of water and CPA transport, influencing cryoprotective efficacy.