342
FINDLAY E. RUSSELL
dark staining nuclei covers the vacuolated layer. On the surface is
a thin layer of dense, cornified material in which no cell or nuclear
detail remains (Russell and Lewis, 1956).
Fleury (1950) states that in Myliobatis aquila the venom is evacuated
through one or two “ excretory canals or their ramifications in the
interdental space ”. We have been unable to reach the same conclusions after studies on the venom apparatus of Urolophus halleri and
Myliobatis californicus. The “ ducts ” described by Fleury are very
similar to those we have noted as blood vessels. Many of our sections
show blood cells in these structures. It is not particularly clear from
Fleury’s paper (which has been called to my attention by Dr. M.
Castex of Argentina, to whom I am indebted), from whence these ducts
arise and where they terminate. However, we have been preparing
serial sections from the full length of the stings from several species
of stingrays in order to evaluate Fleury’s contention.
2. Chemistry and toxicology
The freshly prepared water extract of crude venom is clear, colorless,
or faintly gray in color. It has a fishy taste and ammoniacal odor.
Its pH is 6-76. The crude extract loses its toxicity within 4-18 h on
standing at room temperatures. It is more stable at lower temperatures
or in 20 to 40% glycerol. Most of the toxicity is lost on lyophilization.
Total protein was found to be approximately 30%, total nitrogen 3%
and total carbohydrate 3%. Ten amino acids were identified by paper
chromatography. Several unidentified amino acids were also present.
It was suggested that the crude toxin was a protein of average molecular
weight (Russell et al., 195813).
Using disc electrophoresis we have recently identified 15 fractions
in extracts from the venom-containing tissues of Urolophus halleri.
Extracts prepared from sponges, which had been stabbed with fresh
stings, contained 10 fractions. Further studies on these extracts,
using gel filtration (Sephadex G 100 and G 200), suggest that the
toxic protein(s) may have a molecular weight in excess of 100,000.
The fraction showing the greatest lethal activity was found to have
two or three distinct bands when subjected to disc electrophoresis.
Further studies showed that the crude extracts contained serotonin,
5-nucleotidase and phosphodiesterase. There was no protease or
phospholipase activity.
The venom is known to exert a deleterious effect on the mammalian
cardiovascular system. Low concentrations of the venom give rise to
simple peripheral vasodilatation or vasoconstriction.
The most
consistent change seen in the electrocardiographic pattern of cats when
FINDLAY E. RUSSELL
dark staining nuclei covers the vacuolated layer. On the surface is
a thin layer of dense, cornified material in which no cell or nuclear
detail remains (Russell and Lewis, 1956).
Fleury (1950) states that in Myliobatis aquila the venom is evacuated
through one or two “ excretory canals or their ramifications in the
interdental space ”. We have been unable to reach the same conclusions after studies on the venom apparatus of Urolophus halleri and
Myliobatis californicus. The “ ducts ” described by Fleury are very
similar to those we have noted as blood vessels. Many of our sections
show blood cells in these structures. It is not particularly clear from
Fleury’s paper (which has been called to my attention by Dr. M.
Castex of Argentina, to whom I am indebted), from whence these ducts
arise and where they terminate. However, we have been preparing
serial sections from the full length of the stings from several species
of stingrays in order to evaluate Fleury’s contention.
2. Chemistry and toxicology
The freshly prepared water extract of crude venom is clear, colorless,
or faintly gray in color. It has a fishy taste and ammoniacal odor.
Its pH is 6-76. The crude extract loses its toxicity within 4-18 h on
standing at room temperatures. It is more stable at lower temperatures
or in 20 to 40% glycerol. Most of the toxicity is lost on lyophilization.
Total protein was found to be approximately 30%, total nitrogen 3%
and total carbohydrate 3%. Ten amino acids were identified by paper
chromatography. Several unidentified amino acids were also present.
It was suggested that the crude toxin was a protein of average molecular
weight (Russell et al., 195813).
Using disc electrophoresis we have recently identified 15 fractions
in extracts from the venom-containing tissues of Urolophus halleri.
Extracts prepared from sponges, which had been stabbed with fresh
stings, contained 10 fractions. Further studies on these extracts,
using gel filtration (Sephadex G 100 and G 200), suggest that the
toxic protein(s) may have a molecular weight in excess of 100,000.
The fraction showing the greatest lethal activity was found to have
two or three distinct bands when subjected to disc electrophoresis.
Further studies showed that the crude extracts contained serotonin,
5-nucleotidase and phosphodiesterase. There was no protease or
phospholipase activity.
The venom is known to exert a deleterious effect on the mammalian
cardiovascular system. Low concentrations of the venom give rise to
simple peripheral vasodilatation or vasoconstriction.
The most
consistent change seen in the electrocardiographic pattern of cats when