174
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
1.5-2.5 p in diameter, with one to four small endosomes each measuring
0.5 p in diameter; a vacuole, 1-5-2.5 p in diameter, at interior end of
spore in which a small “ body ” is sometimes seen (Fig. 62) as is a rod
within wall (Fig. 63) ; sporocyst spherical, 30-80 p in diameter,
enclosing variable number of spores, from sixteen to over 100.
Life cycle. The complete life cycle of H . tumefacientis is not known.
According to Taylor (1966), the invasive form for mussels is most
probably an amoebula which gives rise to a plasmodium through
repeated division of its nucleus coupled with an increase in size.
Spores are formed within each fully developed plasmodium (now known
as a cyst) when spore walls develop around each nucleus. At first
each spore only possesses a single thin membrane and a centrally
located nucleus enclosing a single large endosome. It is only in the
older spores that the delicate outer membrane appears. It is composed
in part of one or two compactly wrapped filaments. It is also in the
older spores that the endospore fragments into as many as four smaller
bodies. The number of spores within each sporocyst (i.e. the membrane
of the original plasmodium enclosing spores) varies from sixteen to
over 100. Upon reaching maturity, the sporocyst wall ruptures and the
spores are released. These are set free in the lumina of the digestive
gland tubules and are believed to be expelled from the molluscan host
via the excretory products or may reinfect the same host although it is
highly doubtful.
Taylor has attempted to infect both Mytilus californianus and M .
edulis by injecting tumefaction brei. His experiments were unsuccessful.
Ecology. Of the 1 114 M . californianus examined by Taylor,
twenty-three, or 2.1 yo, were infected.
Physiology. Nothing is known about the physiology of H . tumefacientis except for certain histochemical observations contributed by
Taylor. The walls of nearly mature spores include a PAS (periodic
acid-Schiff)-positive but diastase resistant thickened portion which is
believed to be the developing operculum but the definitive operculum is
PAS-negative. The cytoplasm of the mature spore is strongly PASpositive but diastase resistant and hence may be assumed not to
represent glycogen. It most probably includes certain neutral mucopolysaccharides, muco- or glycoproteins, or a complex of these. The
cytoplasm is acid fast when stained with Farley’s (1965a) modification
of Ziehl-Neelson’s carbol fuchsin. On the other hand, the cytoplasm
of immature spores is only faintly or not acid fast.
He
employed thioglycollate broth as given by Ray (1952a,b), potatoTaylor also has attempted to culture this haplosporidan.
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
1.5-2.5 p in diameter, with one to four small endosomes each measuring
0.5 p in diameter; a vacuole, 1-5-2.5 p in diameter, at interior end of
spore in which a small “ body ” is sometimes seen (Fig. 62) as is a rod
within wall (Fig. 63) ; sporocyst spherical, 30-80 p in diameter,
enclosing variable number of spores, from sixteen to over 100.
Life cycle. The complete life cycle of H . tumefacientis is not known.
According to Taylor (1966), the invasive form for mussels is most
probably an amoebula which gives rise to a plasmodium through
repeated division of its nucleus coupled with an increase in size.
Spores are formed within each fully developed plasmodium (now known
as a cyst) when spore walls develop around each nucleus. At first
each spore only possesses a single thin membrane and a centrally
located nucleus enclosing a single large endosome. It is only in the
older spores that the delicate outer membrane appears. It is composed
in part of one or two compactly wrapped filaments. It is also in the
older spores that the endospore fragments into as many as four smaller
bodies. The number of spores within each sporocyst (i.e. the membrane
of the original plasmodium enclosing spores) varies from sixteen to
over 100. Upon reaching maturity, the sporocyst wall ruptures and the
spores are released. These are set free in the lumina of the digestive
gland tubules and are believed to be expelled from the molluscan host
via the excretory products or may reinfect the same host although it is
highly doubtful.
Taylor has attempted to infect both Mytilus californianus and M .
edulis by injecting tumefaction brei. His experiments were unsuccessful.
Ecology. Of the 1 114 M . californianus examined by Taylor,
twenty-three, or 2.1 yo, were infected.
Physiology. Nothing is known about the physiology of H . tumefacientis except for certain histochemical observations contributed by
Taylor. The walls of nearly mature spores include a PAS (periodic
acid-Schiff)-positive but diastase resistant thickened portion which is
believed to be the developing operculum but the definitive operculum is
PAS-negative. The cytoplasm of the mature spore is strongly PASpositive but diastase resistant and hence may be assumed not to
represent glycogen. It most probably includes certain neutral mucopolysaccharides, muco- or glycoproteins, or a complex of these. The
cytoplasm is acid fast when stained with Farley’s (1965a) modification
of Ziehl-Neelson’s carbol fuchsin. On the other hand, the cytoplasm
of immature spores is only faintly or not acid fast.
He
employed thioglycollate broth as given by Ray (1952a,b), potatoTaylor also has attempted to culture this haplosporidan.