126
A.P.A. Wiihrmann
small amounts. Antifreezes are the nonglycosylated AFP in the case of
zoarcids and liparidids, and the AFGPs in Pogonophryne spp. and
Bathydraco spp. Moreover, Bathydraco spp., distributed in the cold water
of the Filchner Depression, synthesize additional AFP in the same
concentration as the AFGP. Antifreeze activity is 0.84 °C at a peptide
-1
concentration of 40 mg ml . So far, these peptides have not been further
characterized [21].
The measurable thermal hysteresis (0.1-0.5 0c) of blood serum of
several deep-living species (e.g. Muraenolepis marmoratus, Paraliparis
somovi, Neopagetopsis ionah, Bathydraco spp.) suggests that the serum
contains modest amounts of antifreezes, but that this does not lower the
freezing point of serum sufficiently to protect these species from freezing
at the usual -1.9 °C surface temperature in the Shelf Surface Water.
Combined with elevated osmolality of body fluids, a widespread
phenomenon in polar teleosts, the freezing point depression of serum in
deep water species is only 0.98-1.38 °C below the freezing point of pure
water.
However, the freezing behavior of the serum of Paraliparis somovi is
similar to that reported for some northern boreal species [24]. The
freezing points are not well defined and the ice growth in the serum
progresses through periods of stops and starts as the temperature is
lowered. In other nonnotothenioid species from the Lazarev Sea (e.g.
Macrourus holotrachys and Lycenchelys hureaui) freezing point
depression of serum could not be detected due to the extremely low
concentrations of the antifreeze peptides.
Summary
The lipid content in liver and muscle of notothenioid fish decreases with
the development of gonads and starvation experiments with Trematomus
eulepidotus indicate that high-Antarctic notothenioids can survive long
periods of food shortage due to their low metabolic rates. Notothenioid
species have low concentrations of highly glycosylated gangliosides.
These gangliosides are concentrated at the synaptic membraneous proteins
like ATPase, kinase and receptors. The concentration and composition of
antifreeze compounds depend on the ambient water temperature, the depth
of habitat, the level of activity, and the mode of life of the specimens.
Sluggish and benthic species possess higher amounts of antifreezes than
they would need in their natural habitat. Antifreeze concentration of more
active as well as benthopelagic or pelagic species is exactly tailored to the
A.P.A. Wiihrmann
small amounts. Antifreezes are the nonglycosylated AFP in the case of
zoarcids and liparidids, and the AFGPs in Pogonophryne spp. and
Bathydraco spp. Moreover, Bathydraco spp., distributed in the cold water
of the Filchner Depression, synthesize additional AFP in the same
concentration as the AFGP. Antifreeze activity is 0.84 °C at a peptide
-1
concentration of 40 mg ml . So far, these peptides have not been further
characterized [21].
The measurable thermal hysteresis (0.1-0.5 0c) of blood serum of
several deep-living species (e.g. Muraenolepis marmoratus, Paraliparis
somovi, Neopagetopsis ionah, Bathydraco spp.) suggests that the serum
contains modest amounts of antifreezes, but that this does not lower the
freezing point of serum sufficiently to protect these species from freezing
at the usual -1.9 °C surface temperature in the Shelf Surface Water.
Combined with elevated osmolality of body fluids, a widespread
phenomenon in polar teleosts, the freezing point depression of serum in
deep water species is only 0.98-1.38 °C below the freezing point of pure
water.
However, the freezing behavior of the serum of Paraliparis somovi is
similar to that reported for some northern boreal species [24]. The
freezing points are not well defined and the ice growth in the serum
progresses through periods of stops and starts as the temperature is
lowered. In other nonnotothenioid species from the Lazarev Sea (e.g.
Macrourus holotrachys and Lycenchelys hureaui) freezing point
depression of serum could not be detected due to the extremely low
concentrations of the antifreeze peptides.
Summary
The lipid content in liver and muscle of notothenioid fish decreases with
the development of gonads and starvation experiments with Trematomus
eulepidotus indicate that high-Antarctic notothenioids can survive long
periods of food shortage due to their low metabolic rates. Notothenioid
species have low concentrations of highly glycosylated gangliosides.
These gangliosides are concentrated at the synaptic membraneous proteins
like ATPase, kinase and receptors. The concentration and composition of
antifreeze compounds depend on the ambient water temperature, the depth
of habitat, the level of activity, and the mode of life of the specimens.
Sluggish and benthic species possess higher amounts of antifreezes than
they would need in their natural habitat. Antifreeze concentration of more
active as well as benthopelagic or pelagic species is exactly tailored to the