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N de Terra

Publications and source records attributed to N de Terra.

4 recordsLinked to original sources
PubMed1985

Does the oral apparatus of the ciliate Stentor inhibit oral development by release of a diffusible substance?

In the ciliate Stentor, many thousands of basal bodies assemble on the ventral cell surface to form a new oral apparatus during cell division, regeneration and reorganization (oral replacement during interphase). During interphase, oral development is normally inhibited by the presence of the anteriorly placed oral apparatus. A glass needle was used to cut the oral apparatus of interphase stentors in two so that the parts remained intact but separate at the anterior end of the cell. These cells initiated basal body assembly and oral development, usually within 8 h. Basal body assembly can therefore result from disconnection of fibrous structures within the oral apparatus but is unlikely to be regulated by an inhibitor diffusing from it.

Animals↗
PubMed1985

Cytoskeletal discontinuities in the cell body cortex initiate basal body assembly and oral development in the ciliate Stentor.

My previous work has shown that disconnecting the oral apparatus of Stentor into two parts induces mass assembly of basal bodies on the ventral cell surface and thus initiates oral development. This operation severs the extensive microtubule tracts joining the oral membranelles at their bases. To determine whether basal body assembly and oral development are also induced by permanently disconnecting the longitudinal microtubule fibre tracts (mt fibre tracts) of the cell body cortex, I interposed a ring of inverted (heteropolar) cortex between the anterior and posterior halves of interphase stentors. When successful, this operation made it impossible for these fibre tracts to rejoin at the heteropolar boundaries and always induced basal body assembly and oral development in the graft complex. By contrast, tripartite homopolar graft complexes rarely initiated oral development; when they did, it was apparently in response to the presence of disproportionately small oral structures, which is the normal stimulus for oral development in Stentor. The mt fibre tracts of tripartite homopolar grafts also eventually became continuous. These results support the hypothesis that permanent, extensive discontinuities anywhere within the cortical cytoskeleton can trigger basal body assembly and oral development. Since the onset of these processes is known to initiate cell division in Stentor, the results also suggest that development of discontinuities within the cortical cytoskeleton during interphase growth may be the endogenous stimulus initiating cell division in Stentor.

Animals↗
PubMed1975

Evidence for cell surface control of macronuclear DNA synthesis in Stentor.

In cell grafts, Stentor macronuclei associated with separate regions of cell surface can be made asynchronous with regard to morphology and DNA synthesis even though they demonstrably share a common endoplasm. These results suggest a mechanism for nuclear differentiation within a single cytoplasmic compartment, based on cell surface differences.

Animals↗