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  • 1
    Electronic Resource
    Electronic Resource
    Selective mirror-image reversal of ciliary patterns inTetrahymena thermophila homozygous for ajanus mutation (1984)
    Springer
    Development genes and evolution 194 (1984), S. 107-120 
    Details
    ISSN: 1432-041X
    Keywords: Cellular asymmetry reversal ; Cell surface patterns ; Mutations affecting patterns ; Ciliate development ; Tetrahymena thermophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of the oral apparatus (OA) and of neighboring ciliary structures ofTetrahymena thermophila was analyzed in cells homozygous for ajanus (jan A) mutation plus a recessiveenhancer of janA (eja). Such cells frequently possess two OAs located on opposite sides of the cell, a primary (1°) OA previously reported to be normal, and a secondary (2°) OA previously reported to express a mirror-reversal of right-left asymmetry. This study confirms the reality of a reversal in the gross orientation of membranelles in most developing 2° OAs. It also shows that there is a reversal of asymmetry in the pattern of resorption of basal bodies of ciliary rows adjacent to the 2° OA, and in the arrangement of basal-body couplets making up the portion of the apical “crown” of the cell situated close to the 2° OA. However, the locations at which membranelles of the 2° OA become modified during late phases of oral development remain normal, so that membranelles of 2° OAs are superimposable on those of 1° OAs. In addition, the membranelles of 2° OAs frequently undergo a rotation during the final phases of oral development, so that even their spatial orientation becomes normal. This mixture of reversed and normal features can be accounted for by postulating a superimposition of a reversed largescale asymmetry on a normal local asymmetry of ciliary units. This postulate predicts that no single mutation can bring about a complete mirror-image reversal of ciliary patterns. 1° OAs appear normal by light microscopy. However, detailed analysis of SEM, preparations of isolated 1° OAs indicate subtle abnormalities of basal body arrangement in some of these OAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848350
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  • 2
    Electronic Resource
    Electronic Resource
    bcd: A mutation affecting the width of organelle domains in the cortex of Tetrahymena thermophila (1987)
    Springer
    Development genes and evolution 196 (1987), S. 421-433 
    Details
    ISSN: 1432-041X
    Keywords: Cell surface patterns ; Mutations affecting patterns ; Ciliate development ; Tetrahymena thermophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A single-gene recessive mutation, bcd (broadened cortical domains), of Tetrahymena thermophila is characterized by a variable broadening of the spatial domains within which cortical organelles, including both the contractile vacuole pores (CVP) and oral apparatus (OA), are formed. The phenotype is not temperature-sensitive. During the development of the organelles of the mutant prior to cell division, extra CVPs and extra oral primordia (OP) appear near ciliary rows adjacent to the rows at which these structures normally form. In the later stages of development, some, but not all, of these extra structures are resorbed, or in the case of the oral domain, multiple adjacent OPs may be completely or partially integrated into a single enlarged OA. When multiple OAs persist, one or more of these may display a reversed orientation reminiscent of those encountered in janus mutants. However, unlike janus, bcd cells do not express any sign of a mirror-image global organization. Our results can best be accounted for by postulating that the bcd mutation affects some common determinant of the widths of both CVP and OA domains. Studies are in progress which explore the relationship between this width-determining mechanism(s) and the mechanism(s) determining the location of cortical organelles around the cell circumference.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00399142
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  • 3
    Electronic Resource
    Electronic Resource
    Interactions between janus and bcd cortical pattern mutants in Tetrahymena thermophila (1988)
    Springer
    Development genes and evolution 197 (1988), S. 476-489 
    Details
    ISSN: 1432-041X
    Keywords: Cell surface patterns ; Double mutant analysis ; Ciliate development ; Tetrahymena thermophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An analysis of bcd, janA; bcd, janB; and bcd, janC double-mutant phenotypes in Tetrahymena thermophila has allowed us to examine patterning processes affected by two different classes of mutations. bcd brings about a broadening of the oral and contractile vacuole pore domains in the ciliate cortex, while the janus mutations generate a mirror-image duplication of the ventral cortical pattern. We observed both bcd and janus characteristics expressed in the double mutants, as well as features unique to the double-mutant. Temperature-shift experiments employing the temperature-sensitive janB mutation in a double-mutant (bcd, janB) combination allowed us to observe the changes in pattern as a mirror-image geometry was brought into expression and subsequently removed within the bcd, janB double homozygote. These experiments suggest that there are multiple pattern-mechanisms at work with differing kinetics of expression in the ciliate cortex. We discuss how the bcd mutation could influance expression of the janus mutations in light of a model previously proposed to account for the janus phenotype.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385681
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  • 4
    Electronic Resource
    Electronic Resource
    Spontaneous Astomy: Loss of Oral Areas in Glaucoma chattoni (1961)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 8 (1961), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Specimens of Glaucoma chattoni lacking in oral areas and unable to divide were observed in both axenic and bacterized cultures. The frequency of incidence of astomy rose in the course of continued cultivation of G. chattoni A, which was the strain most extensively studied.Observations on silver impregnated animals from mass cultures, and studies of individually isolated living ciliates, have both led to the conclusion that all cells destined to become astomous pass through a certain definite sequence of events. These axe: 1. Initial damage, not microscopically detectable, predisposes the cell in such a way that within a few generattons all of its progeny become astomous. 2. The ability to complete normal stomatogenesis is lost; the cell cannot maintain normal posterior oral anlagen and also cannot regenerate following damage to the existing oral area. At this stage the cell can still divide, so that astomous opisthes are produced. 3. The existing oral area disappears shortly after the ability to produce new oral areas is lost. Loss of ability to divide occurs simultaneously with loss of oral areas. 4. Finally, there is increasing disorganization of the kineties, gradually decreasing activity and death.The incidence of astomy was compared in several different strains of G. chattoni, including two newly isolated from nature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1961.tb01211.x
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  • 5
    Electronic Resource
    Electronic Resource
    The Patterning of Ciliates (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: This past-presidential address considers the relationship between small-scale assembly and large-scale patterning in ciliates. Certain model examples of assembly-based patterning are reviewed, followed by the introduction of Williams and Honts' concept of “meta-assembly” as applied to the development of the oral apparatus. The major part of this review then explores two topics: the nature and origin of large-scale circumferential order, and the manner by which the large-scale order of cell directions influences the organization of membranelles of the oral apparatus. In this review, I summarize an existing formal description of large-scale positional order, allude to a more precise abstract theoretical model, and end with a brief discussion of the problem of searching for molecular mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04827.x
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  • 6
    Electronic Resource
    Electronic Resource
    Morphology and Development of Mirror-Image Doublets of Stylonychia mytilus (1990)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 37 (1990), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: This paper describes the cortical anatomy and development of mirror-image doublets of Stylonychia mytilus, analyzed using the protargol technique. The reversed, or “left-handed” (LH) component of these doublets is a mirror image of the normal or “right handed” (RH) component with regard to the arrangement of cortical structures. The mirror-image patterning is imperfect, however, as the individual ciliary structures of the LH component all are of normal internal asymmetry, and the orientation of membranelles is inverted. Certain structures that would be expected to form near the line of symmetry are absent. During cell division and cortical reorganization, ciliary primordia arise and become arranged in a mirror-image pattern that is more perfect than that exhibited by the mature structures. Deviations from a mirror-image pattern appear at late stages when organelle sets differentiate within ciliary primordia: for example, the membranelle set differentiates within the oral primordium of the LH component in a sequence that is an inversion rather than a mirror image of the corresponding sequence of the RH component. This mixed control of oral development by different cortical “informational systems” accounts for some of the characteristic abnormalities of the mature oral structures of the LH component.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1990.tb01106.x
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  • 7
    Electronic Resource
    Electronic Resource
    The Stability of Cortical Phenotypes in Continuously Growing Cultures of Tetrahymena pyriformis (1972)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 19 (1972), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Cortical features were analyzed in successive samples of continuously growing stock cultures of amicronucleate strains GL-C and GL-I, and in micronucleate strain WH-6 (syngen 1, mating type I). Thirteen successive samples of strain GL-C, representing a time span of 111 months, 5 samples of WH-6 (43 months) and 2 samples of GL-I (1 month) were examined. The observed range of commonly expressed ciliary row numbers (corticotypes) was 16–20 rows in strain GL-C, 15–20 in strain GL-I, and 16–20 in strain WH-6. These ranges remained constant through time within each strain. The individual samples each included all or a large part of the total range observed in the strain, but the relative abundances of different corticotypes within this range shifted through time. The shifts appeared random, with no discernible trends.Mean contractile vacuole pore (CVP) position and number of CVP meridians were assayed in the 2 “GL” strains. Mean CVP position was an apparently stable character, with only slight fluctuations through time, while the distribution of number of CVP meridians was somewhat less constant. The CVP parameters of strains GL-C and GL-I were considerably different, and both of these strains were very different from the GL strain which had been studied by Nanney. In fact, these 3 “GL” strains have, among them, virtually the entire gamut of known CVP characteristics. The possible significance of these wide differences among strains presumed to be closely related is considered in the Discussion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1972.tb03550.x
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  • 8
    Electronic Resource
    Electronic Resource
    Participation of the Undulating Membrane in the Formation of Oral Replacement Primordia in Tetrahymena pyriformis (1969)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 16 (1969), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. Cells of T. pyriformis GL-C, transferred from a complete axenic medium to a medium lacking amino acids, cease dividing after several hours, and instead begin to undergo oral replacement. This process can be synchronized by a single long 33.8 C treatment. Oral replacement was also observed during stationary phase of normal culture growth in cells of strain GL-C and WH-6 (syngen 1).In strain GL-C the oral replacement primordium is initiated by the appearance of a small number of kinetosomes adjacent to the anterior end of kinety 1, just posterior to the undulating membrane (UM). The UM then loses its cilia and becomes disorganized, and is thus converted into a field of kinetosomes which is broadest near its posterior end. This UM-derived field then becomes joined with the much smaller field which had appeared earlier near the anterior end of kinety 1. As a consequence, the right margin of the UM-derived field becomes continuous with the anterior end of kinety 1, and thus comes to appear as an anterior extension of this kinety. The membranelles and UM of the new oral area differentiate within this composite field. While this is going on, the membranelles of the old oral area are progressively resorbed; these old membranelles always remain spatially separate from the oral replacement primordium.In strain WH-6, the stomatogenic field initially formed adjacent to kinety 1 is substantial, and the role of the UM kinetosomes in stomatogenesis is less obvious than in strain GL-C. The posterior portion of the UM probably contributes to the oral replacement primordium, while the anterior portion is resorbed. In this strain small supernumerary primordia are occasionally seen adjacent to the portion of kinety 2 which is nearest to the posterior region of the UM.It is suggested that the junction between the posterior portion of the UM and the neighboring cortex can serve as an inductive zone for initiation of stomatogenesis, the UM itself having a varying capacity for direct provision of kinetosomes for the stomatogenic field. The flexibility of the stomatogenic site in T. pyriformis is discussed in relation to the apparent restriction of potentialities in peniculine ciliates such as Paramecium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1969.tb02228.x
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  • 9
    Electronic Resource
    Electronic Resource
    Nuclear and Cortical Regulation in Doublets of Paramecium: II. When and How do Two Cortical Domains Reorganize to One? (2001)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 48 (2001), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Homopolar doublets with twofold rotational symmetry were generated in Paramecium tetraurelia and in P. undecaurelia by electrofusion or by arrested conjugation. These doublets underwent a complex cortical reorganization over time, which led to their reversion to singlets. This reorganization involved a reduction in number of ciliary rows, a progressive inactivation and loss of one oral meridian, and a reduction and eventual disappearance of one cortical surface (semicell) situated between the two oral meridians. The intermediate steps of this reorganization included some processes that resemble those previously described in regulating doublets of other ciliates, and others that are peculiar to members of the “P. aurelia” species-group and some of its close relatives. The former included a disappearance of one cortical landmark (a contractile vacuole meridian) and transient appearance of another (a third cytoproct) within the narrower semicell. The latter included a reorganization of the paratene zone and the associated invariant (non-duplicating) region to occupy the entire narrower semicell and a redistribution of zones of most active basal-body proliferation within the opposite, wider semicell. The final steps of reorganization involved anterior displacement, invagination, and resorption of one of the two oral apparatuses and eventual disappearance of the associated oral meridian. An oral meridian deprived of its oral apparatus, either by spontaneous resorption or microsurgical removal, could persist for some time in “incomplete doublets” before regulating to the singlet condition. The phylogenetically widespread events encountered in the regulation of doublets to singlets suggest that Paramecium shares some of the global regulatory properties that are likely to be ancestral in ciliates. The more specific events are probably associated with the complex cytoskeletal architecture of this organism and with the frequent occurrence of autogamy that was described in the preceding study (Prajer et al. 1999).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2001.tb00210.x
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  • 10
    Electronic Resource
    Electronic Resource
    Morphology and Development of Left-Handed Singlets Derived from Mirror-Image Doublets of Stylonychia mytilus (1990)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 37 (1990), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Mirror-image doublets of Stylonychia mytilus include 2 sets of cortical structures, one with the normal “right-handed” (RH) arrangement, the other with a reversed “left-handed” (LH) arrangement. These sets, however, are incomplete, with certain structures, most notably cirri of the right marginal type, missing near the line of symmetry. When a mirror-image doublet is bisected longitudinally to separate the RH and LH components physically, each fragment undergoes a regeneration process that restores a complete set of cortical structures, including the previously missing cirri of the right marginal type. In the resulting LH cell, all ciliary structures are present in an arrangement that is globally reversed in relation to that found in RH cells; in particular, marginal cirri of the left-marginal type are formed at the cell's right margin, and marginal cirri of the right-marginal type are produced at the cell's left margin. Whereas the regenerated RH fragment always divides and initiates a clone of normal singlets, the LH fragment, though structurally nearly complete, in all cases eventually dies without dividing. The cause of death is starvation due to the formation of an abnormal oral apparatus. In the Discussion, we consider the nature and consequences of a reversal of global positional information.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1990.tb01107.x
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