Microtubular systems are an integral and essential
element of eukaryotic cells. Many of these systems display
linkages between the microtubules. The aim of this study was
to investigate one such system, the cytostomal apparatus of
Tetramitus rostratus. It was hoped that some insight could
be gained into the nature of inter-microtubule linkages as
well as investigating conditions for possible isolation via
differential solubilization.
The cytostomal apparatus consists of two sheaves of
microtubules that originate at the basal bodies and extend
through two-thirds of the length of the cell, apparently
supporting the gullet. These microtubules are extremely
stable: they are cold stable, calcium stable and
griseofulvin/colchicine stable. They are highly cross-linked
by fine filaments. These "linkers" have an average length of
107 nm. Linker width varies from the mid-portion (6 nm) to
the ends (12 nm). In this and other respects they are
similar to the highly contested microtrabecular lattice. The
linkers were observed in positively stained samples and in
thin-sections. Glutaraldehyde was found to have a very
destructive effect on the linkers. A combination of
paraformaldehyde and glutaraldehyde (2.25\/0.5\) was found
not to have this effect over times that are normally used for
primary fixation.
Another component of the cytostomal apparatus is the
system of longitudinal filaments that is especially wellrevealed
with high salt (0.25M NaCl or KCl) extraction.
Since this extraction solubilizes the microtubules, it may
allow the longitudinal filaments to be isolated. These
filaments may be related to the tektin filaments found in
flagellar microtubules. In addition, a novel set of crossfibres
is found to originate at the juncture of the two
sheaves of microtubules and fan out across two-thirds of the
width of the apparatus. These fibres were found to be
especially stable in urea which may, again, allow for their
isolation and characterization.
The linkers have been investigated for motility.
Linker length was measured after treatment with ATP (which
successfully reactivated the flagellar dynein) and after
treatment with ATP followed by treatment with calcium (which
efficiently halted all reactivated movement of the flagella).
The length of the ATP treated linkers was very close (5 nm)
to the control linkers and their morphology was
indistinguishable. The length of the calcium treated linkers
was considerable shorter (20 nm) but the morphology suggested
that this was artifactual rather than due to a physiological
cause. / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/22489 |
| Date | 10 1900 |
| Creators | Allen, Linda B |
| Contributors | Dingle, A.D, Biology |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
Page generated in 0.0022 seconds