Table 1.

Characterization of cryoprotectants for high-pressure freezing of whole C. elegans worms.

Cryoprotectant	Adverse effects	Ease of handling	Degree of cryoprotection	Autofluorescence (λex 488 nm, a.u.)
20% BSA	None	+b	+++	80.68
10% glycerol	+a	+++	+++	3.18
0.15 M sucrose	None/+	+++	+++	5.55
20% polyvinyl pyrrolidone (PP)	None	+++	+++	25.35
15% dextran +5% BSA	None	+++	++/+++	38.97
Baker’s yeast paste	N/A	+b	+++	236.88
Perfluorodecalin	+++c	+++	++/+++	0.82
1-Hexadecene	+++c	+++	+++	0.85

Candidates were evaluated in terms of their macroscopic adverse effects and toxicity on C. elegans worms, ease of handling during sample preparation, degree of cryoprotection ascertained by microscopic examination, and autofluorescence. The scores are ranked from none to +++ or for each category based on empirical evidence and observations for the first three parameters, made in our laboratory. Autofluorescence scores are semi-quantitative and represent fluorescence values from up to three images acquired with the same parameters and averaged after masking out areas of contamination.

^aWorms appeared swollen.

^bHigh viscosity of medium.

^cWorms lost structural integrity and became soft and pasty.