Stephen F. W. Ng

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The present study of the cytoskeleton of Paramecium employed a number of heterologous monoclonal antisera raised against intermediate filament proteins of higher organisms, and also an antiserum against a 49 K protein from Tetrahymena. Anti-49 K, and also monoclonal anti-bovine cytokeratin K 8.13 which has a broad cross-reaction spectrum for epithelial(More)
The somatic function of the micronucleus during vegetative propagation of the hypotrichous ciliate Stylonychia mytilus was investigated, by generating amicronucleate cell lines with microinjection or amputation. The amicronucleate cell lines exhibited reduction in fission rate and ingestion shortly after the loss of the micronucleus. There was partial(More)
This report introduces a new system in the study of programming of genomic function during development of the somatic nucleus of Paramecium tetraurelia. Previous works have established a definite, but replaceable, role of the germ nuclei (micronuclei) in oral development in the asexual cycle; their removal from the cell generates viable amicronucleate cell(More)
The contractile vacuole pores (CVPs) in Tetrahymena pyriformis are usually found to the left of ciliary meridians (CVP meridians). When the CVP meridians are experimentally rotated 180 degrees ('inverted'), the CVPs are now found to the right of the rotated CVP meridians. In other words, the CVP is almost invariably found on the same side with respect to(More)
In ciliates, the major morphogenetic events take place in the cortex, a complex of membranes and closely associated filamentous networks. To analyze the problems of assembly and morphogenesis at the molecular level in Paramecium, we have developed a method of purification of cortex fragments which retain their in situ organization and display a highly(More)
The putrescine-biosynthesis pathway in Tetrahymena thermophila was delineated by studying crude extracts prepared from exponentially growing cultures. A pyridoxal phosphate-stimulated ornithine decarboxylase activity competitively inhibited by putrescine was detected. CO2 was also liberated from L-arginine, but analyses by t.l.c. and enzyme studies(More)
Removal of the micronuclei from Paramecium generated amicronucleate cell lines which produced oral apparatuses of much reduced length and abnormal oral membranellar pattern during an initial depression period. They subsequently recovered, but only partially. Reimplantation of the amicronucleates with micronuclei generally allowed a greater oral length to be(More)
Twelve laser-irradiated cell lines and eight cis. platin-treated cultures possessing defective micronuclei exhibited micronuclear and oral abnormalities during autogamy. Micronuclear abnormalities were characterized by the failure of some of the cells to complete the micronuclear cycle resulting in the absence of either micronuclei or macronuclear anlagen,(More)
A temperature-sensitive mutant homozygous for the recessive gene molb in Tetrahymena thermophila offers opportunity for studying the direction of microtubule assembly in vivo. At 39 degrees C the mutant fails to divide properly; the 2 daughter animals remain attached and bend over each other. As revealed by protargol staining, the bending results in acute(More)
Fifteen amicronucleate cell lines and 22 cell lines with defective micronuclei were obtained following selective laser microbeam irradiation of the micronucleus. The amicronucleate cell lines showed reduced growth rate and formed abnormal oral apparatuses in asexual reproduction, and failed to produce any oral apparatus in autogamy, in agreement with(More)