The Oxidative Metabolism of Antarctic Fish:
Some Peculiar Aspects of Cold Adaptation
Bruno Giardina, Alvaro Mordente, Bruno Zappacosta, Cinzia Calla, Luigi
Colacicco, Maria L. Gozzo, and Silvio Lippa
Institute of Chemistry and Clinical Chemistry, Catholic University of Rome and
CNR Cent 7 r for Receptors Chemistry, L.go F. Vito 1,00168 Rome, Italy
Introduction
Environmental factors are key determinants in the process of adaptation
and evolution of living organisms. In this respect, analysis of biological
systems from Antarctic fish may provide valuable insights on the
molecular and cellular strategies which have been adopted in response to
the very low environmental temperature which characterizes Antarctica.
Hence, the temperature of the Antarctic Ocean varies from -1.86 °C at
high latitudes to +5 °C towards the Antarctic Convergence. Moreover,
seasonal variations in temperature are less than 0.2 °C close to the
permanent ice shelf [1] and only 2.5 °C in the northern Antarctic [2]. Very
likely these conditions have existed relatively unchanged for several
million years [3]. Antarctic fish have therefore been forced to become
highly specialized to cold conditions [4]. This extreme specialization is
outlined by the fact that a water temperature of - 1.8 °C, near the freezing
point of sea water, is a condition which would be lethal for virtually all
other fish. Among antarctic fishes the strong challenge of this extreme
environmental condition has been overcome by a number of physiological
and biochemical adaptation mechanisms, the most striking of which is the
synthesis of freezing-point depressing molecules (antifreeze molecules),
either peptides or glycopeptides, which protect the organism from ice
crystal formation in a noncolligative way [5]. In addition, hematocrit of the
blood is either substantially reduced or erythrocytes and hemoglobin are
absent as in Channichthyidae [6-8]. This phenomenon could find an
explanation considering that the very low temperature of sea water would
result in a great increase of blood viscosity; hence, the decrease in the
number of erythrocytes and in the amount of hemoglobin counteract the
temperature-induced viscosity increase, greatly facilitating the cardiac
work. However, these key adaptations do not play any role in establishing
the adaptive metabolic strategies which make it possible for Antarctic fish
to survive under these extreme conditions. Thus, the work done in the last
G. di Prisco, E. Pisano, A. Clarke (Eds)
Fishes of Antarctica. A biological overview
© Springer-Verlag Italia 1998
Some Peculiar Aspects of Cold Adaptation
Bruno Giardina, Alvaro Mordente, Bruno Zappacosta, Cinzia Calla, Luigi
Colacicco, Maria L. Gozzo, and Silvio Lippa
Institute of Chemistry and Clinical Chemistry, Catholic University of Rome and
CNR Cent 7 r for Receptors Chemistry, L.go F. Vito 1,00168 Rome, Italy
Introduction
Environmental factors are key determinants in the process of adaptation
and evolution of living organisms. In this respect, analysis of biological
systems from Antarctic fish may provide valuable insights on the
molecular and cellular strategies which have been adopted in response to
the very low environmental temperature which characterizes Antarctica.
Hence, the temperature of the Antarctic Ocean varies from -1.86 °C at
high latitudes to +5 °C towards the Antarctic Convergence. Moreover,
seasonal variations in temperature are less than 0.2 °C close to the
permanent ice shelf [1] and only 2.5 °C in the northern Antarctic [2]. Very
likely these conditions have existed relatively unchanged for several
million years [3]. Antarctic fish have therefore been forced to become
highly specialized to cold conditions [4]. This extreme specialization is
outlined by the fact that a water temperature of - 1.8 °C, near the freezing
point of sea water, is a condition which would be lethal for virtually all
other fish. Among antarctic fishes the strong challenge of this extreme
environmental condition has been overcome by a number of physiological
and biochemical adaptation mechanisms, the most striking of which is the
synthesis of freezing-point depressing molecules (antifreeze molecules),
either peptides or glycopeptides, which protect the organism from ice
crystal formation in a noncolligative way [5]. In addition, hematocrit of the
blood is either substantially reduced or erythrocytes and hemoglobin are
absent as in Channichthyidae [6-8]. This phenomenon could find an
explanation considering that the very low temperature of sea water would
result in a great increase of blood viscosity; hence, the decrease in the
number of erythrocytes and in the amount of hemoglobin counteract the
temperature-induced viscosity increase, greatly facilitating the cardiac
work. However, these key adaptations do not play any role in establishing
the adaptive metabolic strategies which make it possible for Antarctic fish
to survive under these extreme conditions. Thus, the work done in the last
G. di Prisco, E. Pisano, A. Clarke (Eds)
Fishes of Antarctica. A biological overview
© Springer-Verlag Italia 1998