268
FINDLAY E. RUSSELL
activity is destroyed on heating. When maintained at an alkaline pH
there is a loss of both the hemolytic and ichthyotoxic activities. More
recent studies by Reich and Spiegelatein indicate that a number of
chrysomonad flagellates may be toxic (Parnas, personal communication,
1964).
C . Toxicology
Determinations of the lethal dose of the poison under varying
conditions and in different animals have been carried out by a number
of workers. These studies indicate that this poison is one of the most
lethal biological toxins known. Sommer et al. (1937) found that the dry
weight of 3000 Gonyaulax was approximately 15 pg (about 150/, of the
wet weight), and that this quantity yielded 1 pg of the toxin, or 1
mouse unit. A mouse unit, or average lethal dose, was defined as the
amount of toxin that would kill a 20 g mouse in 15 min with signs of
paralysis or respiratory failure (Prinzmetal et al., 1932 ; Sommer and
Meyer, 1937). Subsequently, various testing methods and assays were
studied by Medcof et al. (1947), Meyer (1953), and McFarren et al.
(1956). McFarren and associates found the oral LD,, per kg body
weight to vary considerably with the animal used and with its strain
and weight. Their figures would indicate that the human is twice as
susceptible to the poison as the dog and approximately four times more
susceptible than the mouse.
In 1955 a Canadian-United States Conference on Shellfish Toxicology adopted a bioassay based on the use of the purified toxin
isolated by Schantz and his colleagues (1958). Studies utilizing the
methods outlined by the Conference indicate that the intraperitoneal
minimal lethal dose of the toxin for the mouse is approximately
9.0 pg/kg body weight. The intravenous minimal lethal dose for the
rabbit is 3.0-4.0 pg/kg of body weight. The minimal lethal oral dose
for man is thought to be between 1.0-4.0 mg. Wiberg and Stephenson
(1960) demonstrated that the LD,, of the purified toxin in mice was:
Oral route
263 (251-267) pg/kg
Intravenous route
3.4 (3.2-3-6) pg/kg
Intraperitoneal route
10.0 (9.7-10'5) pg/kg
Female mice were more susceptible than males, and increases in the
pH or addition of sodium ions to the injection medium reduced the
lethal activity.
In 1932, Prinzmetal et al. demonstrated that the poison from
Mytilus californianus was slowly absorbed from the gastrointestinal
tract and rapidly excreted by the kidneys. It depressed respiration, the
FINDLAY E. RUSSELL
activity is destroyed on heating. When maintained at an alkaline pH
there is a loss of both the hemolytic and ichthyotoxic activities. More
recent studies by Reich and Spiegelatein indicate that a number of
chrysomonad flagellates may be toxic (Parnas, personal communication,
1964).
C . Toxicology
Determinations of the lethal dose of the poison under varying
conditions and in different animals have been carried out by a number
of workers. These studies indicate that this poison is one of the most
lethal biological toxins known. Sommer et al. (1937) found that the dry
weight of 3000 Gonyaulax was approximately 15 pg (about 150/, of the
wet weight), and that this quantity yielded 1 pg of the toxin, or 1
mouse unit. A mouse unit, or average lethal dose, was defined as the
amount of toxin that would kill a 20 g mouse in 15 min with signs of
paralysis or respiratory failure (Prinzmetal et al., 1932 ; Sommer and
Meyer, 1937). Subsequently, various testing methods and assays were
studied by Medcof et al. (1947), Meyer (1953), and McFarren et al.
(1956). McFarren and associates found the oral LD,, per kg body
weight to vary considerably with the animal used and with its strain
and weight. Their figures would indicate that the human is twice as
susceptible to the poison as the dog and approximately four times more
susceptible than the mouse.
In 1955 a Canadian-United States Conference on Shellfish Toxicology adopted a bioassay based on the use of the purified toxin
isolated by Schantz and his colleagues (1958). Studies utilizing the
methods outlined by the Conference indicate that the intraperitoneal
minimal lethal dose of the toxin for the mouse is approximately
9.0 pg/kg body weight. The intravenous minimal lethal dose for the
rabbit is 3.0-4.0 pg/kg of body weight. The minimal lethal oral dose
for man is thought to be between 1.0-4.0 mg. Wiberg and Stephenson
(1960) demonstrated that the LD,, of the purified toxin in mice was:
Oral route
263 (251-267) pg/kg
Intravenous route
3.4 (3.2-3-6) pg/kg
Intraperitoneal route
10.0 (9.7-10'5) pg/kg
Female mice were more susceptible than males, and increases in the
pH or addition of sodium ions to the injection medium reduced the
lethal activity.
In 1932, Prinzmetal et al. demonstrated that the poison from
Mytilus californianus was slowly absorbed from the gastrointestinal
tract and rapidly excreted by the kidneys. It depressed respiration, the