44
EDWARD C. CANTINO AND JAMES S. LOVETT
treating the parent cell from which they are derived with actidione
(cycloheximide), or increased with diphenylamine (Cantino and
Horenstein, 1956a).
(d) And finally, a single flagellum, ca. 20 μ long (Cantino and Hyatt,
1953a) of the whiplash variety (Sparrow, 1960).
More recently, this picture of the spore has been clarified and modified
by electron microscopy (Cantino et al., 1963) ; the essential details are as
follows (Fig. 3) :
The massive nuclear cap encloses the anterior end of the nucleus and
is separated from it by a double membrane; round pores of ca. 100 ιημ
diameter occur along this membrane. Although pores have been seen in
the nuclear membranes of other organisms (Watson, 1955 ; refs. therein),
they connect the nucleus with the cytoplasm; in B. emersonii, they
connect the nucleus to another, cytoplasmic organelle. Obviously, this
situation could have a real bearing upon possible mechanisms of nucleic
acid translocation (see discussion in Morton, 1961) between the nucleus
and its environment.
The nucleus contains a nucleolus at its posterior end. The cap and its
associated nucleus is surrounded by a double membrane. In all of these
respects, the spore of B. emersonii is very similar to that of the motile
cells in its close relative, Allomyces (Turian and Kellenberger, 1956;
Blondel and Turian, 1960 ; however, see Section III, G).
The single flagellum possesses the now classical (Manton, 1952;
Hoffman-Berling, 1959) 9-plus-2 structure. While the flagellar apparatus
enters through the posterior end of the spore, its flagellar sheath does
not; it ends, instead, at the spore body where it becomes confluent with
the outer membrane of the spore. The two, central fibres of the tail
appear to terminate at or very near the posterior end of the nucleus.
While the fate of the nine, outer fibres is not known with certainty
(however, see below), it is likely that they are linked to one or two
'rootlets' (Fig. 3). Since the flagella of many water-moulds are said to
terminate in blepharoplasts (refs. in Sparrow, 1960; Waterhouse, 1962),
and since in other micro-organisms such as bacteria, flagella may arise
from granules or blepharoplasts (Kerridge, 1961), it is noteworthy that
no basal granule obviously corresponding to a blepharoplast is detectable
in the spore of B. emersonii.
The most striking and provocative observation made with the electron
microscope was this : in the spore of Blastocladiella emersonii, there is
one—and only one—large mitochondrion (Fig. 3); but, aside from its
extraordinary size (relative to the volume of the spore), it possesses a
classical structure, with cristae arising by invagination of the inner
element of a double membrane. Attached to it peripherally are electrondense particles which react strongly-positive to Sudan-IV.
EDWARD C. CANTINO AND JAMES S. LOVETT
treating the parent cell from which they are derived with actidione
(cycloheximide), or increased with diphenylamine (Cantino and
Horenstein, 1956a).
(d) And finally, a single flagellum, ca. 20 μ long (Cantino and Hyatt,
1953a) of the whiplash variety (Sparrow, 1960).
More recently, this picture of the spore has been clarified and modified
by electron microscopy (Cantino et al., 1963) ; the essential details are as
follows (Fig. 3) :
The massive nuclear cap encloses the anterior end of the nucleus and
is separated from it by a double membrane; round pores of ca. 100 ιημ
diameter occur along this membrane. Although pores have been seen in
the nuclear membranes of other organisms (Watson, 1955 ; refs. therein),
they connect the nucleus with the cytoplasm; in B. emersonii, they
connect the nucleus to another, cytoplasmic organelle. Obviously, this
situation could have a real bearing upon possible mechanisms of nucleic
acid translocation (see discussion in Morton, 1961) between the nucleus
and its environment.
The nucleus contains a nucleolus at its posterior end. The cap and its
associated nucleus is surrounded by a double membrane. In all of these
respects, the spore of B. emersonii is very similar to that of the motile
cells in its close relative, Allomyces (Turian and Kellenberger, 1956;
Blondel and Turian, 1960 ; however, see Section III, G).
The single flagellum possesses the now classical (Manton, 1952;
Hoffman-Berling, 1959) 9-plus-2 structure. While the flagellar apparatus
enters through the posterior end of the spore, its flagellar sheath does
not; it ends, instead, at the spore body where it becomes confluent with
the outer membrane of the spore. The two, central fibres of the tail
appear to terminate at or very near the posterior end of the nucleus.
While the fate of the nine, outer fibres is not known with certainty
(however, see below), it is likely that they are linked to one or two
'rootlets' (Fig. 3). Since the flagella of many water-moulds are said to
terminate in blepharoplasts (refs. in Sparrow, 1960; Waterhouse, 1962),
and since in other micro-organisms such as bacteria, flagella may arise
from granules or blepharoplasts (Kerridge, 1961), it is noteworthy that
no basal granule obviously corresponding to a blepharoplast is detectable
in the spore of B. emersonii.
The most striking and provocative observation made with the electron
microscope was this : in the spore of Blastocladiella emersonii, there is
one—and only one—large mitochondrion (Fig. 3); but, aside from its
extraordinary size (relative to the volume of the spore), it possesses a
classical structure, with cristae arising by invagination of the inner
element of a double membrane. Attached to it peripherally are electrondense particles which react strongly-positive to Sudan-IV.