TAURINE I N MARINE INVERTEBRATES
231
gonads of Astropecten aurantiacus Grey. In fact, they were the first to
observe that the presence of organic nitrogenous substances in a free
state would be important in the osmotic regulation of marine invcrtebrates and that this might be particularly true for poikilosmotic animals.
Kurtz and Luck (1935) found large quantities of taurine in the polychaete Audouinia. They extracted 6-22 g taurinelkg of fresh whole
worms and over 3% in fresh body wall muscle. They correlated this
with the black layer of sulphurous mud that occurs around the tubes
of these worms. They noted that other polychaetes, Glycera and Nereis
obtained only a few feet from the Audouinia and on the same occasion
did not have the black deposit around them. Only Nereis gave taurine
on analysis, and then only in trace quantities. Similarly, estimations
on the tissues of the sipunculid Urechis caupo, Fisher and MacGinitie,
the phoronid Phoronopsis harmeri Pixell, and Lumbricus all gave
negative results. The authors appreciated the limitations of the
extinction method they used, but determinations of the sulphur content
of the " taurine fraction " indicate that it is impossible that taurine
could be present in quantity in the species they examined except in the
case of Audouinia. Kurtz and Luck (1935) also determined the totd
non-protein nitrogen and amino nitrogen of Audouinia and Nereis and
found that in both cases the quantities were of the same order and that
taurine must constitute most of the amino nitrogen present in
dudouinia. While they could offer no explanation for the difference
they do point out that in addition to any excretory function that might
be ascribed to the taurine of Audouinia (note the sulphur deposits
around the worm) the high concentration of taurine will make it
important osmotically and they put forward the idea that it may act
as a zwitter ion. As a zwitter ion it would give one ion per molecule at
the isoelectric point, and two ions per molecule at a pH sufficiently
removed from it. In the latter case an amount of taurine as large as the
3% found in Audouinia would give a high enough osmotic pressure to
balance a large proportion of the osmotic pressure of the surrounding
aea water.
Kurtz and Luck (1935) commented on the fact that at that time
large amounts of taurine had only been found in marine animals. This
has indeed proved true. Thus Simpson et al. (1959) determined the free
amino acid content of seventeen marine invertebrates and found
taurine in all varying from 2 pM/g tissue to 70 pM/g tissue. Because
taurine content appeared t o vary with the environment they extended
their analyses to land, freshwater and brackish water molluscs and
found none in freshwater and terrestrial species but found taurine in
brackish and marine species (Table VIII). They point out that the
231
gonads of Astropecten aurantiacus Grey. In fact, they were the first to
observe that the presence of organic nitrogenous substances in a free
state would be important in the osmotic regulation of marine invcrtebrates and that this might be particularly true for poikilosmotic animals.
Kurtz and Luck (1935) found large quantities of taurine in the polychaete Audouinia. They extracted 6-22 g taurinelkg of fresh whole
worms and over 3% in fresh body wall muscle. They correlated this
with the black layer of sulphurous mud that occurs around the tubes
of these worms. They noted that other polychaetes, Glycera and Nereis
obtained only a few feet from the Audouinia and on the same occasion
did not have the black deposit around them. Only Nereis gave taurine
on analysis, and then only in trace quantities. Similarly, estimations
on the tissues of the sipunculid Urechis caupo, Fisher and MacGinitie,
the phoronid Phoronopsis harmeri Pixell, and Lumbricus all gave
negative results. The authors appreciated the limitations of the
extinction method they used, but determinations of the sulphur content
of the " taurine fraction " indicate that it is impossible that taurine
could be present in quantity in the species they examined except in the
case of Audouinia. Kurtz and Luck (1935) also determined the totd
non-protein nitrogen and amino nitrogen of Audouinia and Nereis and
found that in both cases the quantities were of the same order and that
taurine must constitute most of the amino nitrogen present in
dudouinia. While they could offer no explanation for the difference
they do point out that in addition to any excretory function that might
be ascribed to the taurine of Audouinia (note the sulphur deposits
around the worm) the high concentration of taurine will make it
important osmotically and they put forward the idea that it may act
as a zwitter ion. As a zwitter ion it would give one ion per molecule at
the isoelectric point, and two ions per molecule at a pH sufficiently
removed from it. In the latter case an amount of taurine as large as the
3% found in Audouinia would give a high enough osmotic pressure to
balance a large proportion of the osmotic pressure of the surrounding
aea water.
Kurtz and Luck (1935) commented on the fact that at that time
large amounts of taurine had only been found in marine animals. This
has indeed proved true. Thus Simpson et al. (1959) determined the free
amino acid content of seventeen marine invertebrates and found
taurine in all varying from 2 pM/g tissue to 70 pM/g tissue. Because
taurine content appeared t o vary with the environment they extended
their analyses to land, freshwater and brackish water molluscs and
found none in freshwater and terrestrial species but found taurine in
brackish and marine species (Table VIII). They point out that the