46
EDWARD C. CANTINO AND JAMES S. LOVETT
Without question, this big mitochondrion
is the 'side body' seen
previously with the light microscope—fonti
nulla fides. In sharp contrast
with the numerous and smaller mitochondria seen in the motile cells of
Allomyces (Turian and Kellenberger, 1956; Blondel and Turian, 1960),
this 'triton among the minnows' is situated asymmetrically, and it
extends up one side almost to the anterior end of the nuclear cap. It
completely surrounds the base of the flagellum, with the unsheathed
fibres running through it in one, and possibly two channels. The
disposition of the flagellum and its relation to the mitochondrion is
discussed in greater detail elsewhere (Cantino et ah, 1963). The refractile
granules are visibly aligned in a single layer adjacent to the mitochondrion but separated from the cytoplasm by a double membrane ; their
strongly osmiophilic nature buttresses the thought that they may be
mainly lipid. On the surface, the situation in Blastocladiella is reminiscent
of spermatogenesis (Fawcett, 1959), where mitochondria gather around
the base of flagella ; however, they subsequently elongate and then wrap
around the axial bundle of fibrils to form a mitochondrial sheath. The
presence of this single, giant mitochondrion in the motile cell of B.
emersonii may, for the moment, represent a unique situation among
fungi ; and yet, what better illustration of the law of parsimony.
The cytoplasm of the spore is lightly granular, but does not contain an
endoplasmic reticulum. Its electron scattering power is very low. The
only recognizable inclusions are some strongly osmiophilic organelles,
bound by single membranes, which could conceivably be lysosomes (or
'cytosomes' ; see Novikoff, 1960). However, they are not at all similar to
the lobed osmiophilic granules of Allomyces (Blondell and Turian, 1960).
Almost certainly, however, they must be the 'gamma' particles (Cantino
and Horenstein, 1956a) seen with the light microscope. The possible
structure of these interesting bodies has been discussed in more detail
elsewhere (Cantino et ah, 1963).
If cell differentiation generally involves a notable increase in the
extent and complexity of the endoplasmic reticulum (Fawcett, 1959),
then the spore of B. emersonii would have to be classified as a notably
undifferentiated cell. And yet, it is richly endowed with conspicuous
organelles; on this basis, it is most emphatically a differentiated one.
But when it is recalled that the spore of Blastocladiella is prone to take
on the character of an amoeba at the slightest provocation (Cantino and
Hyatt, 1953a), then one is also reminded of Brachet's (1950) suggestion
that the linear-fibrous array in cytoplasm may provide a cell with
strength and rigidity. Perhaps, then, the dilemma is resolved ; this fungus
s warmer is, indeed, a highly differentiated cell which, during its
evolutionary history, was forced to sacrifice endoplasmic reticulation
for more animate perambulation.
EDWARD C. CANTINO AND JAMES S. LOVETT
Without question, this big mitochondrion
is the 'side body' seen
previously with the light microscope—fonti
nulla fides. In sharp contrast
with the numerous and smaller mitochondria seen in the motile cells of
Allomyces (Turian and Kellenberger, 1956; Blondel and Turian, 1960),
this 'triton among the minnows' is situated asymmetrically, and it
extends up one side almost to the anterior end of the nuclear cap. It
completely surrounds the base of the flagellum, with the unsheathed
fibres running through it in one, and possibly two channels. The
disposition of the flagellum and its relation to the mitochondrion is
discussed in greater detail elsewhere (Cantino et ah, 1963). The refractile
granules are visibly aligned in a single layer adjacent to the mitochondrion but separated from the cytoplasm by a double membrane ; their
strongly osmiophilic nature buttresses the thought that they may be
mainly lipid. On the surface, the situation in Blastocladiella is reminiscent
of spermatogenesis (Fawcett, 1959), where mitochondria gather around
the base of flagella ; however, they subsequently elongate and then wrap
around the axial bundle of fibrils to form a mitochondrial sheath. The
presence of this single, giant mitochondrion in the motile cell of B.
emersonii may, for the moment, represent a unique situation among
fungi ; and yet, what better illustration of the law of parsimony.
The cytoplasm of the spore is lightly granular, but does not contain an
endoplasmic reticulum. Its electron scattering power is very low. The
only recognizable inclusions are some strongly osmiophilic organelles,
bound by single membranes, which could conceivably be lysosomes (or
'cytosomes' ; see Novikoff, 1960). However, they are not at all similar to
the lobed osmiophilic granules of Allomyces (Blondell and Turian, 1960).
Almost certainly, however, they must be the 'gamma' particles (Cantino
and Horenstein, 1956a) seen with the light microscope. The possible
structure of these interesting bodies has been discussed in more detail
elsewhere (Cantino et ah, 1963).
If cell differentiation generally involves a notable increase in the
extent and complexity of the endoplasmic reticulum (Fawcett, 1959),
then the spore of B. emersonii would have to be classified as a notably
undifferentiated cell. And yet, it is richly endowed with conspicuous
organelles; on this basis, it is most emphatically a differentiated one.
But when it is recalled that the spore of Blastocladiella is prone to take
on the character of an amoeba at the slightest provocation (Cantino and
Hyatt, 1953a), then one is also reminded of Brachet's (1950) suggestion
that the linear-fibrous array in cytoplasm may provide a cell with
strength and rigidity. Perhaps, then, the dilemma is resolved ; this fungus
s warmer is, indeed, a highly differentiated cell which, during its
evolutionary history, was forced to sacrifice endoplasmic reticulation
for more animate perambulation.