TAURINE IN MARINE INVERTEBRATES
233
or out of the muscle fibres and partly by the increase or decrease of the
total content of sodium, chloride and free amino acids in the muscles.
Similarly Lynch and Wood (1966) in experiments on Crassostrea
showed that with increasing environmental salinity the concentration
of taurine in the body increased, as did that also of glycine, alanine and
proline. Pctersen and nuerr (1969) did not find any direct relationship
in the case of the prosobranch Tegula, rather the reverse. However,
they report a direct relationship with a n unidentified compound, which
could possibly be isethionic acid. Clearly these experiments should be
repeated.
Surveys on the amino acid content of marine, brackish- and freshwater crustaceans have shown that amino acid concentrations are
greater in muscle of marine species than in that of freshwater species,
in both cases the amino acid concentration of the blood is low in comparison with muscle (Camien et al., 1951). Duchiiteau and Florkin
(1955) found that in Eriocheir there was little difference in the proportions of the different amino acids of the pool at different salinities but
that the concentration of all constituent amino acids was greater in sea
water than in fresh water. They (DuchAteau and Florkin, 1956) found
that this was also true of Carcinus maenas. They also refer t o both these
decapods as being " poikilosmotic ) ) when in fact these animals exhibit
some maintenance of the osmotic pressure of the blood thus buffering
the effect of the external medium on the cells.
The regulation of the cell volume and of the total number of moles
of intracellular solutes-later termed isosmotic intracellular regulation
by Jeuniaux et a2. (196l)-involves the constituent amino acids. They
effect the opposition to the movement of water between the cells and the
internal medium which would otherwise result from the variations in
concentration of the latter. Thus in marine invertebrates the concentration of certain amino acids and taurine in cells often exceeds that in
the extracellular body fluid by several magnitudes (Florkin, 1963;
Lange, 1965, 1968). The maintenance of this high concentration indicates that mechanisms exist for the active transport of taurine against
covsiderable gradients. It apparently enters the cell in part by active
transport at a specific site for amino acids, in part by active transport
a t a less well defined site and in part by simple diffusion (Christensen,
1964; Christensen et al., 1954; Kromphardt, 1963). The concentration of
amino acids and taurine in the cells is in part dependant on the osmolarity of the surrounding fluid, but it appears that any change is
related only to a small extent t o an apparent change in hydration of the
tissues (Jeaniaux et al., 1961 ; Bricteux-Grbgoire et al., 1962, 1964s
and b ; Lange, 1968). Lange (1963, 1968) points out that in Mytilus,
233
or out of the muscle fibres and partly by the increase or decrease of the
total content of sodium, chloride and free amino acids in the muscles.
Similarly Lynch and Wood (1966) in experiments on Crassostrea
showed that with increasing environmental salinity the concentration
of taurine in the body increased, as did that also of glycine, alanine and
proline. Pctersen and nuerr (1969) did not find any direct relationship
in the case of the prosobranch Tegula, rather the reverse. However,
they report a direct relationship with a n unidentified compound, which
could possibly be isethionic acid. Clearly these experiments should be
repeated.
Surveys on the amino acid content of marine, brackish- and freshwater crustaceans have shown that amino acid concentrations are
greater in muscle of marine species than in that of freshwater species,
in both cases the amino acid concentration of the blood is low in comparison with muscle (Camien et al., 1951). Duchiiteau and Florkin
(1955) found that in Eriocheir there was little difference in the proportions of the different amino acids of the pool at different salinities but
that the concentration of all constituent amino acids was greater in sea
water than in fresh water. They (DuchAteau and Florkin, 1956) found
that this was also true of Carcinus maenas. They also refer t o both these
decapods as being " poikilosmotic ) ) when in fact these animals exhibit
some maintenance of the osmotic pressure of the blood thus buffering
the effect of the external medium on the cells.
The regulation of the cell volume and of the total number of moles
of intracellular solutes-later termed isosmotic intracellular regulation
by Jeuniaux et a2. (196l)-involves the constituent amino acids. They
effect the opposition to the movement of water between the cells and the
internal medium which would otherwise result from the variations in
concentration of the latter. Thus in marine invertebrates the concentration of certain amino acids and taurine in cells often exceeds that in
the extracellular body fluid by several magnitudes (Florkin, 1963;
Lange, 1965, 1968). The maintenance of this high concentration indicates that mechanisms exist for the active transport of taurine against
covsiderable gradients. It apparently enters the cell in part by active
transport at a specific site for amino acids, in part by active transport
a t a less well defined site and in part by simple diffusion (Christensen,
1964; Christensen et al., 1954; Kromphardt, 1963). The concentration of
amino acids and taurine in the cells is in part dependant on the osmolarity of the surrounding fluid, but it appears that any change is
related only to a small extent t o an apparent change in hydration of the
tissues (Jeaniaux et al., 1961 ; Bricteux-Grbgoire et al., 1962, 1964s
and b ; Lange, 1968). Lange (1963, 1968) points out that in Mytilus,