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  • 1
    Electronic Resource
    Electronic Resource
    Chromosome constitution of highly motile mouse sperm (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 27 (1990), S. 168-172 
    Details
    ISSN: 1040-452X
    Keywords: Motility ; Genetics ; Sex chromosome ratio ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In this study, we address the relationship between motility and genetic content of mouse sperm. The chromosome complements of highly motile mouse sperm, selected using the swim-up technique, were analyzed after in vitro fertilization, at the first cleavage state. They were compared to those of unselected sperm. Identification of male and female chromosome sets was possible because of their differential condensation at the first mitotic division. In vitro fertilization, swim-up separation, chromosome preparation, and staining were carried out using standard techniques. The results indicate that highly motile mouse sperm did not differ in types and frequencies of chromosomal abnormalities from those not selected for motility. Moreover, separation of motile sperm does not deviate the sex ratio from the theoretical 1:1.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080270213
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  • 2
    Electronic Resource
    Electronic Resource
    Inheritance of the group I rDNA intron in Tetrahymena pigmentosa (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 13 (1992), S. 133-142 
    Details
    ISSN: 0192-253X
    Keywords: Group I introns ; intron homing ; rDNA inheritance in Tetrahymena ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have previously argued from phylogenetic sequence data that the group I intron in the rRNA genes of Tetrahymena was acquired by different Tetrahymena species at different times during evolution. We have now approached the question of intron mobility experimentally by crossing intron+ and intron- strains looking for a strong polarity in the inheritance of the intron (intron homing). Based on the genetic analysis we find that the intron in T. pigmentosa is inherited as a neutral character and that intron+ and intron- alleles segregate in a Mendelian fashion with no sign of intron homing. In an analysis of vegetatively growing cells containing intron+ and intron- rDNA, initially in the same macronucleus, we similarly find no evidence of intron homing.During the course of this work, we observed to our surprise that progeny clones from some crosses contained three types of rDNA. One possible explanation is that T. pigmentosa has two rdn loci in contrast to the single locus found in T. thermophila. Some of the progeny clones from the genetic analysis were expanded for several hundred generations, and allelic assortment of the rDNA was demonstrated by subcloning analysis. © 1992 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020130207
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  • 3
    Electronic Resource
    Electronic Resource
    Immunocytochemical analysis of secretion mutants of Tetrahymena using a mucocyst-specific monoclonal antibody (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 13 (1992), S. 151-159 
    Details
    ISSN: 0192-253X
    Keywords: Tetrahymena ; mutants ; secretion ; mucocysts ; immunofluorescence ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Dense-core granules represent an adaptation of specialized secretory cell to facilitate stimulus-regulated release of stored proteins. Such granules are a prominent feature of mammalian neuroendocrine and exocrine cells and are also well developed in the ciliates. In Tet-rahymena thermophila, the ability to generate mutants in dense-core granule biosynthesis and fusion presents a versatile system for dissecting steps in regulated exocytosis. We have previously shown that defective granules in such mutants could be characterized by several biochemical criteria, including buoyant density, which increases during maturation, and the degree of proteolytic processing of the content precursors. We have now used indirect immunofluorescence, taking advantage of a monoclonal antibody directed against a granule protein, to visualize the morphology and distribution of both granules and putative granule intermediates in mutant and wild-type cells. The results are consistent with the biochemical analysis and extend our characterization of the mutants, allowing us to distinguish four classes. In addition, the assay represents a powerful technique for diagnosis of new mutants. © 1992 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020130209
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  • 4
    Electronic Resource
    Electronic Resource
    Locus-dependent profiles of the rescue of nonexcitable behavioral mutants during conjugation in Tetrahymena thermophila (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 13 (1992), S. 174-179 
    Details
    ISSN: 0192-253X
    Keywords: Conjugation rescue ; Tetrahymena ; nonexcitable mutant ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The Tetrahymena nonreversal (TNR) mutants of Tetrahymena thermophila are behavioral mutants with nonexcitable membranes. When cells of the tnrB mutant were mated with wild type, a phenotypic change occurred about l h after pair formation. The pairs began to lose their heterotypic character in stimulation solution containing high potassium and, within 1 1/2h, they were not distinguishable from the wild-type homotypic pairs. On the contrary, although pairs of the tnrA and wild type also lost their heterotypic character about 1 1/2 h after pair formation, they never showed a full response as wild-type homotypic pairs. When tnrA was mated with tnrB more than 50% of pairs expressed a heterotypic pair character 2 h after pair formation, consistent with the tnrB defect having been rescued but not the tnrA defect. Thus, conjugation rescue of the mutant phenotype is locus dependent and probably reflects the nature of the gene products controlling voltage-dependent Ca2+ channels. © 1992 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020130212
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  • 5
    Electronic Resource
    Electronic Resource
    Lithium-Induced respecification of pattern in Paramecium (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 13 (1992), S. 194-202 
    Details
    ISSN: 0192-253X
    Keywords: Cellular morphogenesis ; polyphos-photidylinositide cycle ; myo-inositol ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The long-known teratogenic effects (dorsalisation) of lithium on amphibian embryos has recently raised renewed interest. As it is known that lithium blocks the polyphosphoinositide (PI) cycle, causing a depressed level of myo-inositol, and as injections of myo-inostiol have been shown to rescue the effects of Li+, it was postulated that Li+ causes a flattening of gradients of PI cycle activity underlying the developmental polarities. We have studied the effect of Li+ on the morphogenesis of the unicellular organism, Paramecium. We show (1) that exposure to 25 mM Li+ during division yields precise distorsions of the cortical pattern that can be explained by a uniformisation of surface growth i.e. partial suppression of the right/left and antero/posterior asymmetries and (2) that Li+ effects are rescued by injection of myo- inositol. These results suggest that spatially graded activity of the PI cycle (ensuring in turn a spatially graded distribution of secondary messengers directly involved in the morphogenetic processes) appeared early in evolution. © 1992 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020130304
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  • 6
    Electronic Resource
    Electronic Resource
    The influence of fission line expression on the number and positioning of oral primordia in the cdaA1 mutant of Tetrahymena thermophila (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 13 (1992), S. 216-222 
    Details
    ISSN: 0192-253X
    Keywords: Tetrahymena ; partial cytokinesis ; Positioning ; cdaA1 mutant ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: During cytokinesis, furrowing creates new boundaries for daughter cells. Following a shift to a restrictive temperature, cells of the temperature-sensitive cell-division-arrest (cdaA1) mutant of Tetrahymena thermophila complete development of the oral apparatus for the prospective posterior daughter cell before becoming arrested in cytokinesis. When maintained under weak restrictive conditions (35°C), some of the chains were arrested prior to the start of fission line formation (D-shaped chains), whereas others manifested rudimentary unilateral furrowing on the ventral side (B-shaped chains). In their second cell cycle following the temperature shift, the D-shaped chains usually formed only one oral primordium, at a position highly correlated with the length of the entire chain. The B-shaped chains always produced two separate oral primordia, located at irregular positions anterior and posterior to the division furrow, often close to the posterior oral apparatus produced during the first cycle. These results suggest that the formation of the fission line sets a reference boundary to assess the number of oral primordia and influence their position, that appear during subsequent morphogenetic episodes. They also indicate that, during cell division cycles, pre-existing oral apparatuses do not strongly inhibit the formation of new oral apparatuses in their close vicinity. © 1992 Wiley-Liss, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020130307
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  • 7
    Electronic Resource
    Electronic Resource
    Nuclear functions in postconjugational development of Paramecium caudatum: Ability to form food vacuoles analyzed by nuclear elimination and implantation (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 13 (1992), S. 223-228 
    Details
    ISSN: 0192-253X
    Keywords: Micronucleus ; macronucleus ; conjugation ; oral apparatus ; nuclear transplantation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Paramecium caudatum loses the ability to form food vacuoles at the crescent stage of the micronucleus from 5 to 6 hr after the initiation of conjugation and regains it immediately after the third division of the zygotic nucleus. To assess the micronuclear function in the development of the oral apparatus after coniugation, prezygotic micronuclei was removed from cells at various stages of conjugation, and their ability to form food vacuoles were examined. (1) When all of the prezygotic micronuclear derivatives were eliminated before the stage of formation of the zygotic nucleus, the exconjugant did not regain its ability. (2) When a zygotic nucleus or postzygotic nuclei were removed, in some cases the cell formed as many food vacuoles as did nonoperated cells after conjugation, while in other operated cells the number of food vacuoles was subnormal. (3) When a micronucleus from a cell at vegetative phase (G1) was transplanted into a cell of an amicronucleate mating pair at the stage between 8 and 9 hr after the initiation of conjugation, the implanted cell regained the ability to form food vacuoles. However, no cell regained the ability when the implantation was carried out within 1 hr after the separation of the mates. The results show that the micronucleus plays an indispensable role in the development of the oral apparatus at the stages of exchange of gametic nuclei and fertilization and that the micronucleus transplanted from asexual cells can fulfill this function. On the other hand, removal of the macronucleus from exconjugants showed that the maternal macronucleus also has an indispensable function in regaining the ability to form food Vacuoles. © 1992 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020130308
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  • 8
    Electronic Resource
    Electronic Resource
    Isolation of the Lembadion-factor, A morphogenetically active signal, that induces Euplotes cells to change from their ovoid form into a larger lateral winged morph (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 13 (1992), S. 241-246 
    Details
    ISSN: 0192-253X
    Keywords: Lembadion-factor ; cell-transformation ; Euplotes octocarinatus ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A morphogenetically active substance released by the predatory ciliate Lem-badion bullinum is recognized by ciliates of the genus Euplotes, which are potential prey organisms of Lembadion. The substance (L-factor) induces cells of the genus Euplotes to become less compact, which reduces their likelihood of becoming engulfed. Under the influence of this Lembadion- derived signal, E. octocarinatus develops extended wings and dorsal and ventral ridges and transforms within a few hours from its typical ovoid morph into an enlarged circular morph. This takes place without cell division. We have isolated the L-factor and report that it is a protein with a mass of 31,500 Da. The factor has been purified to chromatographic and electrophoretic homogeneity and was found to be active at concentrations as low as 10-12 mol/L. © 1992 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020130311
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  • 9
    Electronic Resource
    Electronic Resource
    Directed positioning of nuclei in living Paramecium tetraurelia: Use of the laser optical force trap for developmental biology (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 13 (1992), S. 235-240 
    Details
    ISSN: 0192-253X
    Keywords: Micronuclei ; laser tweezers ; micro-manipulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have constructed a laser optical force trap (“laser tweezers”) by coupling an Nd:YAG laser to an optical microscope with a high numerical aperture objective. The laser beam (approximately 0.1 W power) is focused to a diffraction-limited spot at the specimen plane of the objective: the wavelength chosen (1,064 nm) is not strongly absorbed by most biological materials and is thus not ablative. Because the intensity of the laser beam increases towards the center of the focal spot, small particles brought near the spot will be attracted to the center and held there. Movement of the laser beam will tend to move any trapped particles with it. The laser tweezers can permit precise, nondestructive repositioning of small structures inside a living cell, without recourse to micromanipulators. Initial work has involved the use of laser tweezers on cells of Paramecium tet-raurelia held by a rotocompressor. We have been able to trap and reposition small organelles, especially the highly refractile structures known as crystals. Using a trapped crystal as a “tool”, we have been able to push micronuclei and other structures for many micrometers to virtually any desired location in a cell. In spite of extended exposure of specific structures and of individual cells to the laser beam, no damage has been detectible. Exposed cells, which were removed from the rotocompres-sor and cultured, showed complete viabilty. The laser tweezers technique shows tremendous potential for applications to the study of many fundamental cellular and developmental phenomena in paramecia and other ciliates. For example, we intend to use this technique to investigate temporal and spatial characteristics of nuclear determining regions during sexual reorganization in Paramecium. © 1992 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020130310
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  • 10
    Electronic Resource
    Electronic Resource
    Generation of Minute phenotypes by a transformed antisense ribosomal protein gene (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 13 (1992), S. 256-263 
    Details
    ISSN: 0192-253X
    Keywords: Minute mutations ; oogenesis ; Drosophila ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Antisense RNAs have been used for gene interference experiments in many cell types and organisms. However, relatively few experiments have been conducted with antisense genes integrated into the germ line. In Drosophila reduced ribosomal protein (r-protein) gene function has been hypothesized to result in a Minute phenotype. In this report we examine the effects of antisense r-protein 49 expression, a gene known to correspond to a Minute mutation An antisense rp49 gene driven by a strong and inducible promoter was transformed into the Drosophila germ line. Induction of this gene led to the development of flies with weak Minute phenotypes and to the transient arrest of oogenesis. Parameters that may affect the success of antisense gene inactivation are discussed. © 1992 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020130403
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