Freezing survival, body ice content and blood composition of the freeze-tolerant European common lizard, Lacerta vivipara.
To investigate the freeze tolerance of the European common lizard, Lacerta vivipara, we froze 17 individuals to body temperatures as low as -4 degrees C under controlled laboratory conditions. The data show that this species tolerates the freezing of 50% of total body water and can survive freezing exposures of at least 24-h duration. Currently, this represents the best known development of freeze tolerance among squamate reptiles. Freezing stimulated a significant increase in blood glucose levels (16.15+/- 1.73 micromol x ml(-1) for controls versus 25.06 +/- 2.92 micromol x ml(-1) after thawing) but this increase had no significant effect on serum osmolality which was unchanged between control and freeze-exposed lizards (506.0 +/- 23.8 mosmol x l(-1) versus 501.0 +/- 25.3 mosmol x l(-1), respectively). Tests that assessed the possible presence of antifreeze proteins in lizard blood were negative. Recovery at 5 degrees C after freezing was assessed by measurements of the mean time for the return of breathing (5.9 +/- 0.5 h) and of the righting reflex (44.8 +/- 4.5 h). Because this species hibernates in wet substrates inoculative freezing may frequently occur in nature and the substantial freeze tolerance of this lizard should play a key role in its winter survival.
Voituron
Y
Y
Laboratoire d'Ecologie, Fonctionnent et Evolution des Systèmes Ecologiques, Ecole Normale Supérieure, Paris, France.
Storey
J M
JM
Grenot
C
C
Storey
K B
KB
D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D021301:Antifreeze Proteins / Q000097:blood; D001786:Blood Glucose; D005615:Freezing; D007035:Hypothermia / Q000097:blood / Q000401:mortality / Q000503:physiopathology*; D007053:Ice; D008116:Lizards / Q000502:physiology*; D009994:Osmolar Concentration
D021301:Antifreeze Proteins; D001786:Blood Glucose; D007053:Ice