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Donald A. Levin - One of the best experts on this subject based on the ideXlab platform.
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RESPONSE TO SELECTION ON Autogamy IN PHLOX
Evolution; international journal of organic evolution, 1996Co-Authors: Paul J. Bixby, Donald A. LevinAbstract:Two cycles of artificial selection were performed to increase autogamous fruiting in two wild populations of the self-incompatible Phlox drummondii, to decrease autogamous fruiting in two wild populations of the self-compatible Phlox cuspidata, and to both increase and decrease autogamous fruiting in a cultivar of P. drummondii which is pseudo-self-compatible. The breeding systems were determined to be genetically quite flexible, independent of inbreeding depression and other genetic phenomena which could hinder a breeding system shift. This is especially true for increasing Autogamy. Self-pollen-pistil compatibility seems to be the single character affected by selection. Based on the continuous variation in both Autogamy and self-compatibility, we suggest that the change has been due to genes which modify the self-incompatibility reaction rather than to the simple segregation of alleles at the S-locus.
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Effect of inbreeding on Autogamy in Phlox
Heredity, 1995Co-Authors: Donald A. LevinAbstract:The effect of inbreeding on Autogamy was studied in two greenhouse-grown populations of the weakly self-compatible Phlox dmmmondii. Sixty-one plants from a Lytle, TX. population and 20 plants from a Bastrop, TX. population were self-fertilized to generate an equivalent number of 10-plant self families. The mean level of Autogamy in the Lytle progeny was 2.49 per cent vs. 1.03 per cent in their parents. The mean level of Autogamy in the Bastrop progeny was 13.35 per cent vs. 5.95 per cent in their parents. Autogamy within families was continuous and often broadly distributed, suggesting that it was influenced by a segregating polygenic system which modifies S-gene expression. The heritability of Autogamy in the Bastrop population was 0.45, as estimated from the regression of offspring on mid-parent values.
Yoshiomi Takagi - One of the best experts on this subject based on the ideXlab platform.
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A new mutation in the timing of Autogamy in Paramecium tetraurelia.
Mechanisms of ageing and development, 2005Co-Authors: Rie Komori, Terue Harumoto, Hiroaki Sato, Yoshiomi TakagiAbstract:We have isolated a new type of Paramecium tetraurelia mutant, named rie-2, that has a long immaturity period until Autogamy. We previously isolated such an Autogamy mutant, designated rie-1. These two mutants had some additional common features such as dependence of the occurrence of Autogamy on the temperature, involvement of a single recessive gene, lower fission rate and shorter clonal life span. However, rie-2 was considered a new type mutant distinguishable from rie-1 because of their different natures of temperature sensitivity. First, the temperature at which they resembled the wild-type phenotype was low (19 degrees C) in rie-2, although it was high (32 degrees C) in rie-1. Second, the clonal life span of rie-2 at 25 degrees C was similar to that of the wild-type, but it was extremely shorter at 32 degrees C than at 25 degrees C, although it was similarly shorter at both temperatures in rie-1. Third, the difference of the fission rate between mutant and wild-type was greater at 32 degrees C than at 25 degrees C in rie-2, although it was similar at both temperatures in rie-1. This report shows that a gene mutation to elongate the period until sexual maturation does not necessarily assure the long life span.
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A Paramecium tetraurelia mutant that has long Autogamy immaturity period and short clonal life span.
Mechanisms of ageing and development, 2004Co-Authors: Rie Komori, Terue Harumoto, Hiromi Fujisawa, Yoshiomi TakagiAbstract:Abstract We have isolated an unprecedented mutant of Paramecium tetraurelia that has a long immaturity period until Autogamy. This mutant stock, d4-RK, screened for 0% Autogamy at the age of 27 fissions, began to undergo Autogamy around the age of 50 fissions in some clones and underwent Autogamy scarcely even after the age of 100 fissions in others. d4-RK expressed its mutant phenotype at 25 °C, but resembled the wild-type phenotype at 32 °C. Genetic analyses indicated that a single recessive gene, named rie (remote immaturity exit), was responsible for the mutant phenotype. This is the first report to show a gene that elongates the time to sexual maturation in unicellular organisms. The clonal life span was shorter and fission rate was lower in the rie mutant than in the wild-type, both at 25 °C and 32 °C. Even in the fourth autogamous generation following the third backcross to the wild-type, the progeny with the elongated Autogamy immaturity period still had a short clonal life span and low fission rate, while those with the wild-type phenotype in Autogamy immaturity period showed the wild-type phenotypes in clonal life span and fission rate, too.
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variability of Autogamy maturation pattern in genetically identical populations of paramecium tetraurelia
Zoological Science, 2002Co-Authors: Rie Komori, Terue Harumoto, Hiromi Fujisawa, Yoshiomi TakagiAbstract:Autogamy in Paramecium tetraurelia is a form of sexual reproduction in a single cell that results in homozygosity in every genetic locus. Autogamy becomes inducible by natural starvation several fissions after the previous Autogamy, and percent Autogamy increases gradually with clonal age to reach 100%. We here report the degree of variability of the Autogamy-maturation pattern, and how it is inherited through autogamous generations. We assessed the Autogamy-maturation pattern by monitoring percent Autogamy at the ages of 9, 18 and 27 fissions in the wild-type stock 51. To determine how the Autogamy-maturation pattern is inherited, clones that showed the lowest and the highest percent Autogamy at age 18 in a given autogamous generation (Gn) were examined for their percent Autogamy in the next autogamous generation (Gn+1). This procedure was repeated through successive autogamous generations. We found that percent Autogamy at ages 9 and 27 was rather stable (low and high, respectively), while it was extremely variable at age 18 ranging from 3% to 100%. We also found that percent Autogamy at age 18 in the progeny clones was variable irrespective of percent Autogamy at age 18 in the parental clones; there was no regular rule such as producing progeny with higher (or lower) percent Autogamy from parents with lower (or higher) percent Autogamy.
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Factors Controlling the Length of Autogamy-Immaturity in Paramecium tetraurelia
Zoological Science, 1998Co-Authors: Yoshino Ishikawa, Akiko Suzuki, Yoshiomi TakagiAbstract:Abstract Autogamy-immaturity is the period during which Autogamy can not be induced by natural starvation; in Paramecium tetraurelia, Autogamy first becomes induceable at about 7 fissions after the previous Autogamy, and thereafter the percent of cells undergoing Autogamy increases gradually to almost 100% at the clonal age of about 20 fissions and remains at 100% thereafter. The length of Autogamy-immaturity (LAI), determined by plotting the percent of cells in Autogamy versus the number of fissions, was found to be similar in two cultures grown at different fission rates at 25°C and 30°C. This indicates that paramecia count LAI by the number of fissions, not by the calendar time. LAI estimated from the peaks of percent Autogamy through successive autogamous generations was also similar in two continuous cultures grown with different cycles of growth and starvation at 25°C and 30°C, indicating stability of LAI under ordinary laboratory conditions. However, LAI was affected by the cultural age of parameci...
Richard M. Bateman - One of the best experts on this subject based on the ideXlab platform.
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Iterative allogamy-Autogamy transitions drive actual and incipient speciation during the ongoing evolutionary radiation within the orchid genus Epipactis (Orchidaceae).
Annals of Botany, 2019Co-Authors: Gábor Sramkó, Ovidiu Paun, Marie K. Brandrud, Levente Laczkó, Attila Molnár, Richard M. BatemanAbstract:BACKGROUND AND AIMS The terrestrial orchid genus Epipactis has become a model system for the study of speciation via transitions from allogamy to Autogamy, but close phylogenetic relationships have proven difficult to resolve through Sanger sequencing. METHODS We analysed with restriction site-associated sequencing (RAD-seq) 108 plants representing 29 named taxa that together span the genus, focusing on section Epipactis. Our filtered matrix of 12 543 single nucleotide polymorphisms was used to generate an unrooted network and a rooted, well-supported likelihood tree. We further inferred genetic structure through a co-ancestry heat map and admixture analysis, and estimated inbreeding coefficients per sample. KEY RESULTS The 27 named taxa of the ingroup were resolved as 11 genuine, geographically widespread species: four dominantly allogamous and seven dominantly autogamous. A single comparatively allogamous species, E. helleborine, is the direct ancestor of most of the remaining species, though one of the derived autogams has generated one further autogamous species. An assessment of shared ancestry suggested only sporadic hybridization between the re-circumscribed species. Taxa with the greatest inclination towards Autogamy show less, if any, admixture, whereas the gene pools of more allogamous species contain a mixture alleles found in the autogams. CONCLUSIONS This clade is presently undergoing an evolutionary radiation driven by a wide spectrum of genotypic, phenotypic and environmental factors. Epipactis helleborine has also frequently generated many local variants showing inclinations toward Autogamy (and occasionally cleistogamy), best viewed as incipient speciation from within the genetic background provided by E. helleborine, which thus becomes an example of a convincingly paraphyletic species. Autogams are often as widespread and ecologically successful as allogams.
Rie Komori - One of the best experts on this subject based on the ideXlab platform.
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A new mutation in the timing of Autogamy in Paramecium tetraurelia.
Mechanisms of ageing and development, 2005Co-Authors: Rie Komori, Terue Harumoto, Hiroaki Sato, Yoshiomi TakagiAbstract:We have isolated a new type of Paramecium tetraurelia mutant, named rie-2, that has a long immaturity period until Autogamy. We previously isolated such an Autogamy mutant, designated rie-1. These two mutants had some additional common features such as dependence of the occurrence of Autogamy on the temperature, involvement of a single recessive gene, lower fission rate and shorter clonal life span. However, rie-2 was considered a new type mutant distinguishable from rie-1 because of their different natures of temperature sensitivity. First, the temperature at which they resembled the wild-type phenotype was low (19 degrees C) in rie-2, although it was high (32 degrees C) in rie-1. Second, the clonal life span of rie-2 at 25 degrees C was similar to that of the wild-type, but it was extremely shorter at 32 degrees C than at 25 degrees C, although it was similarly shorter at both temperatures in rie-1. Third, the difference of the fission rate between mutant and wild-type was greater at 32 degrees C than at 25 degrees C in rie-2, although it was similar at both temperatures in rie-1. This report shows that a gene mutation to elongate the period until sexual maturation does not necessarily assure the long life span.
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A Paramecium tetraurelia mutant that has long Autogamy immaturity period and short clonal life span.
Mechanisms of ageing and development, 2004Co-Authors: Rie Komori, Terue Harumoto, Hiromi Fujisawa, Yoshiomi TakagiAbstract:Abstract We have isolated an unprecedented mutant of Paramecium tetraurelia that has a long immaturity period until Autogamy. This mutant stock, d4-RK, screened for 0% Autogamy at the age of 27 fissions, began to undergo Autogamy around the age of 50 fissions in some clones and underwent Autogamy scarcely even after the age of 100 fissions in others. d4-RK expressed its mutant phenotype at 25 °C, but resembled the wild-type phenotype at 32 °C. Genetic analyses indicated that a single recessive gene, named rie (remote immaturity exit), was responsible for the mutant phenotype. This is the first report to show a gene that elongates the time to sexual maturation in unicellular organisms. The clonal life span was shorter and fission rate was lower in the rie mutant than in the wild-type, both at 25 °C and 32 °C. Even in the fourth autogamous generation following the third backcross to the wild-type, the progeny with the elongated Autogamy immaturity period still had a short clonal life span and low fission rate, while those with the wild-type phenotype in Autogamy immaturity period showed the wild-type phenotypes in clonal life span and fission rate, too.
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variability of Autogamy maturation pattern in genetically identical populations of paramecium tetraurelia
Zoological Science, 2002Co-Authors: Rie Komori, Terue Harumoto, Hiromi Fujisawa, Yoshiomi TakagiAbstract:Autogamy in Paramecium tetraurelia is a form of sexual reproduction in a single cell that results in homozygosity in every genetic locus. Autogamy becomes inducible by natural starvation several fissions after the previous Autogamy, and percent Autogamy increases gradually with clonal age to reach 100%. We here report the degree of variability of the Autogamy-maturation pattern, and how it is inherited through autogamous generations. We assessed the Autogamy-maturation pattern by monitoring percent Autogamy at the ages of 9, 18 and 27 fissions in the wild-type stock 51. To determine how the Autogamy-maturation pattern is inherited, clones that showed the lowest and the highest percent Autogamy at age 18 in a given autogamous generation (Gn) were examined for their percent Autogamy in the next autogamous generation (Gn+1). This procedure was repeated through successive autogamous generations. We found that percent Autogamy at ages 9 and 27 was rather stable (low and high, respectively), while it was extremely variable at age 18 ranging from 3% to 100%. We also found that percent Autogamy at age 18 in the progeny clones was variable irrespective of percent Autogamy at age 18 in the parental clones; there was no regular rule such as producing progeny with higher (or lower) percent Autogamy from parents with lower (or higher) percent Autogamy.
Akira Yanagi - One of the best experts on this subject based on the ideXlab platform.
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timing of commitment to Autogamy in paramecium bursaria
Japanese Journal of Protozoology, 2010Co-Authors: Akira YanagiAbstract:SUMMARY To elucidate the timing of commitment to Autogamy in Paramecium bursaria, cells were treated with an Autogamy-inducing agent (1.25% methyl cellulose) for 0, 1, 2, 3, 5, and 24 h, and the duration of treatment required for the induction of Autogamy was examined 24-25.5 h after the onset of treatment. Many cells treated for 0-2 h were at the vegetative stage, but many cells treated for 3-24 h were at stages from the third pre-zygotic division to the third post-zygotic division and normally underwent Autogamy. Therefore, treatment with methyl cellulose for 3 h or more is considered necessary for the induction of Autogamy. However, some of the cells treated for 3 h were at the stage of developing either a swollen and spindle-shaped micronucleus or an early round-shaped micronucleus, which is indicative of the premeiotic S phase. This suggests that if cells proceed beyond the stage of an early round-shaped micronucleus, they normally undergo Autogamy, but if not, they terminate at the stage of either a swollen and spindle-shaped micronucleus or an early round-shaped micronucleus. Consequently, cells of P. bursaria are committed to Autogamy just after the stage of an early round-shaped micronucleus (the premeiotic S phase).
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Changes in cell-cell adhesion ability of artificially induced autogamous cells in Paramecium caudatum
2010Co-Authors: Satoshi Ohta, Akira YanagiAbstract:SUMMARY To analyze cell-cell adhesion in Paramecium caudatum, we examined methyl cellulose-induced autogamous cells for their ability to adhere. It was found that the autogamous cells have cell-cell adhesion ability. In addition, we examined the proportion of adhering (conjugating) pairs derived from autogamous cells at various stages (0.5, 1, 2, 4, 6, 9 and 12 h after the onset of induction of Autogamy). The proportion of adhering cells reached a maximum about 2 h after the onset of induction of Autogamy, and thereafter, rapidly decreased by 4 h after the onset, eventually reaching almost zero 6 h after the onset. These results suggest that there is a transient expression or activation of molecule(s) involved in cell-cell adhesion around 2 h after the onset of induction of Autogamy.
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Autogamy is induced in Paramecium bursaria by methyl cellulose
European Journal of Protistology, 2004Co-Authors: Akira YanagiAbstract:When isolated single cells of Paramecium bursaria were treated with 1.25% methyl cellulose, most of the single cells showed nuclear changes which were substantially similar to those seen in conjugation, suggesting that the cells undergo Autogamy. Additional cytological observations indicated that the cells underwent normal nuclear processes during Autogamy. The ability to induce Autogamy will facilitate genetic studies in P. bursaria.
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A simple method of induction of Autogamy by methyl cellulose in Paramecium caudatum
European Journal of Protistology, 1996Co-Authors: Akira Yanagi, Nobuyuki HagaAbstract:Summary We found that methyl cellulose induced Autogamy in Paramecium caudatum . When isolated single cells were treated with 1.25 and 2.5% methyl cellulose, most of the single cells showed Autogamy-specific nuclear changes. This suggests that the cells undergo Autogamy. The simple method, which we have developed, for artificial induction of Autogamy is that cells at low population density are simply treated with 2.5% methyl cellulose in plastic Petri dish. In this method, most of the treated cells underwent nuclear changes without cell-cell adhesion, indicating Autogamy. The present method for the induction of Autogamy will facilitate genetic studies in P. caudatum .
