4. ANALYSIS O F FACTORS INVOLVED M SYMBIOSIS
89
in marine parasitic relationships. Indeed, some of my unpublished data
on Crassostrea virginica parasitized by Bucephalus sporocysts suggest
this. For this reason, what is known about protein and amino acid
utilization by parasites of freshwater molluscs is briefly reviewed below.
The uptake of amino acids in vivo and in vitro by adult trematodes
is known as the result of the studies of Robinson (1961), Senft and Senft
(1962) and Senft (1963). Little is known about the intramolluscan
stages. Friedl (1961c) has analyzed the constituents of the free amino
acid pool of Lymnaea stagnalis jugularis to determine whether there is
any correlation between prevalent amino acids and those found earlier
(Friedl, 196la,b) to favor the in vitro survival rate of the rediae of
Fascioloides magna which utilize this gastropod as the intermediate
host. Of the three amino acids (hydroxyproline, proline and serine)
previously found to favor survival, only serine has been found to be a
major constituent in the mollusc’s serum (plasma). In fact, proline has
been quantitatively determined to be present in the least amount of
seventeen amino acids detected while hydroxyproline has not been
found. Generally speaking, however, alanine, glycine, serine and
threonine, all prominently present in plasma, have been shown to extend
longevity in vitro. These indirect evidences could be interpreted as
suggesting that the potential for uptake of certain amino acids by
intramolluscan trematode larvae exists.
Dusanic and Lewert (1963) have studied alterations in the protein
and amino acid compositions in the plasma of Australorbis glabratus
following infection by Schistosoma mansoni. Although their primary
concern was to detect changes which might reflect molluscan response
in the form of humoral immunity, it is of interest to comment on their
results, especially their findings on changes in the amino acid composition. Using two dimensional paper chromatography involving butanol,
acetic acid, and water (4 : 1 : 1) as the first irrigant and a phenolsaturated solution of 6.3% sodium citrate and 3.7% monobasic sodium
phosphate as the second, these workers detected only three amino
acids, lysine, glycine and proline, in the plasma of uninfected snails.
In 45 min post-miracidial penetration, they detected an increase in all
three of these amino acids but, in addition, they detected the appearance
of two additional amino acids, threonine and leucine. This condition
persists until 2 h post-infection at which time there is a decrease of all
five amino acids, with the disappearance of leucine by the 14th h. By
the 24th h post-infection, the amino acid composition returns to normal.
These workers have inferred that the initial increase in amino acids may
be correlated with the appearance of humoral factors although they did
not state this as a fact. Their findings are of interest since evidence for
89
in marine parasitic relationships. Indeed, some of my unpublished data
on Crassostrea virginica parasitized by Bucephalus sporocysts suggest
this. For this reason, what is known about protein and amino acid
utilization by parasites of freshwater molluscs is briefly reviewed below.
The uptake of amino acids in vivo and in vitro by adult trematodes
is known as the result of the studies of Robinson (1961), Senft and Senft
(1962) and Senft (1963). Little is known about the intramolluscan
stages. Friedl (1961c) has analyzed the constituents of the free amino
acid pool of Lymnaea stagnalis jugularis to determine whether there is
any correlation between prevalent amino acids and those found earlier
(Friedl, 196la,b) to favor the in vitro survival rate of the rediae of
Fascioloides magna which utilize this gastropod as the intermediate
host. Of the three amino acids (hydroxyproline, proline and serine)
previously found to favor survival, only serine has been found to be a
major constituent in the mollusc’s serum (plasma). In fact, proline has
been quantitatively determined to be present in the least amount of
seventeen amino acids detected while hydroxyproline has not been
found. Generally speaking, however, alanine, glycine, serine and
threonine, all prominently present in plasma, have been shown to extend
longevity in vitro. These indirect evidences could be interpreted as
suggesting that the potential for uptake of certain amino acids by
intramolluscan trematode larvae exists.
Dusanic and Lewert (1963) have studied alterations in the protein
and amino acid compositions in the plasma of Australorbis glabratus
following infection by Schistosoma mansoni. Although their primary
concern was to detect changes which might reflect molluscan response
in the form of humoral immunity, it is of interest to comment on their
results, especially their findings on changes in the amino acid composition. Using two dimensional paper chromatography involving butanol,
acetic acid, and water (4 : 1 : 1) as the first irrigant and a phenolsaturated solution of 6.3% sodium citrate and 3.7% monobasic sodium
phosphate as the second, these workers detected only three amino
acids, lysine, glycine and proline, in the plasma of uninfected snails.
In 45 min post-miracidial penetration, they detected an increase in all
three of these amino acids but, in addition, they detected the appearance
of two additional amino acids, threonine and leucine. This condition
persists until 2 h post-infection at which time there is a decrease of all
five amino acids, with the disappearance of leucine by the 14th h. By
the 24th h post-infection, the amino acid composition returns to normal.
These workers have inferred that the initial increase in amino acids may
be correlated with the appearance of humoral factors although they did
not state this as a fact. Their findings are of interest since evidence for