The oatmeal nematode Panagrellus redivivus survives moderately low temperatures by freezing tolerance and cryoprotective dehydration

Supercooling and Freezing Tolerant Animals

“…Other species of nematodes seem to have more modest cold tolerance abilities (Smith et al, 2008), although some have a small amount of freezing tolerance (Hayashi & Wharton, 2011). Tardigrades are thought to be freezing tolerant (Hengherr et al, 2009), although the role played by inoculative freezing and whether ice formation is intracellular or extracellular is yet to be determined in this phylum.…”

“…Nematodes, and animals that live in similar habitats (such as tardigrades and rotifers), are likely to be faced with the risk of inoculative freezing from ice in their surroundings. Few species have been examined in this respect, but in those that have (Panagrolaimus davidi and Panagrellus redivivus) they have little ability to resist inoculative freezing (Hayashi & Wharton, 2011;Wharton & Ferns, 1995;Wharton et al, 2003). This also is the case in the infective larvae of the insect parasitic nematode Steinernema feltiae (Farman & Wharton, unpublished results) and the free-living Antarctic nematode Plectus murrayi (Raymond, 2010).…”

“…However, if freezing of the media occurs at a high subzero temperature (-1°C) inoculative freezing does not occur in P. davidi and the nematode can survive by cryoprotective dehydration (Wharton, et al, 2003). In P. redivivus, however, inoculative freezing occurs in some individuals even at -1°C and the small amount of cold tolerance that this species possesses is largely due to freezing tolerance, although those few nematodes that remain unfrozen survive by cryoprotective dehydration (Hayashi & Wharton, 2011).…”

The ability to survive intracellular freezing in nematodes is related to the pattern and distribution of ice formed

“…after freezing at a temperature (−10°C) that produces intracellular freezing and used vital dyes (Lee et al, 1993) to look for cellular damage. We have also made comparisons with the oatmeal nematode, Panagrellus redivivus (Linnaeus 1767) Goodey 1945, whose natural habitat is thought to be fermenting tree resin, has very low survival after freezing at −10°C (Hayashi and Wharton, 2011); and with another Antarctic nematode with a similar distribution to that of P. davidi, Plectus murrayi Yeates 1970, that has intermediate levels of survival Wharton and Raymond, 2015). We used nematodes grown at 20°C to avoid any starvation effects of cold acclimation in our fed cultures .…”

“…nutrient agar or sand agar plates (Wharton and Raymond, 2015), with a layer of artificial tap water (ATW; Greenaway, 1970) or balanced salt solution (BSS; Piggott et al, 2000). Oatmeal nematodes, Panagrellus redivivus, were sourced from a commercial supplier (as 'microworms', Biosuppliers, Auckland, New Zealand) and cultured on autoclaved rolled oats (Hayashi and Wharton, 2011). Panagrolaimus sp.…”