Genomic instability in a clonal species, Tradescantia commelinoides (Commelinaceae)

Ann Kenton; David Langton; Janet Coleman

doi:10.1139/g88-121

Genomic instability in a clonal species, Tradescantia commelinoides (Commelinaceae)

Genome ◽

10.1139/g88-121 ◽

1988 ◽

Vol 30 (5) ◽

pp. 734-744 ◽

Cited By ~ 2

Author(s):

Ann Kenton ◽

David Langton ◽

Janet Coleman

Keyword(s):

Genomic Instability ◽

Vegetative Reproduction ◽

Control Mechanisms ◽

Spontaneous Breakage ◽

In The Wild ◽

Centric Shift ◽

Clonal Species ◽

Eventual Stability

Within a population of Tradescantia commelinoides collected in the wild, genomic instability is unique to clones having large centric shifts. Initially, the instability is attributable to breakage caused by imperfect separation of abnormally long chromatids, but the more severe effects that sometimes develop are a consequence of spontaneous breakage and reunion and disturbance of control mechanisms. Breakage of excessively long chromatids following repositioning of the centromere may destabilize some segment of DNA important for ordered replication and division. Eventual stability would result from the loss of this segment, or its transfer to a quiescent position. A period of instability, leading to the establishment of a new equilibrium, may represent an important source of variability in species that rely heavily upon vegetative reproduction for their colonizing potential.Key words: Tradescantia, clonal species, centric shift, genomic instability, karyotype orthoselection.

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Vegetative aquaculture of Fucus in the Baltic Sea—obtaining low-fertility biomass from attached or unattached populations?

Journal of Applied Phycology ◽

10.1007/s10811-021-02419-x ◽

2021 ◽

Author(s):

Rafael Meichssner ◽

Peter Krost ◽

Rüdiger Schulz

Keyword(s):

Baltic Sea ◽

Vegetative Reproduction ◽

Culture Conditions ◽

Low Fertility ◽

Natural Fertility ◽

High Fertility ◽

Seedling Biomass ◽

In The Wild ◽

The Baltic ◽

Promising Source

AbstractAn experimental farm has been installed in the Kiel Fjord, western Baltic Sea, aiming at the development of a sustainable production process for Fucus species (Fucus vesiculosus, Fucus serratus). The envisaged cultivation method includes the unattached rearing of thalli in baskets deployed in the sea and their vegetative reproduction. Fertility (i.e., receptacle formation) is expected to be problematic for this approach, because receptacles are terminated in growth and degrade after gamete release. In culture experiments, natural fertility led to only minimal overall growth in F. vesiculosus and even weight loss in F. serratus. Therefore, we tested if long-term unattached cultivation of formerly attached thalli leads to a lowering of fertility by an acclimatization process. However, fertility after 1 and 2 years of unattached cultivation was statistically equal and still comparable to the high fertility of attached populations. Furthermore, we tested if the only known naturally unattached population in the western Baltic Sea near Glücksburg, which remains largely infertile in the wild, keeps its low fertility if put under culture conditions. During an experimental 1-year cultivation, thalli from this population remained almost entirely vegetative (2.0 ± 3.1% fertile apices). Hence, the Glücksburg population is a promising source of aquacultural seedling biomass. Yet, further tests are necessary to check, if the fertility remains low over several years of cultivation. If unattached populations are used as source for commercial cultures, the collection of seedling material should always be accompanied by strong measures to ensure the continued integrity of these valuable habitats.

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Dynamics of age-related catastrophic mitotic failures and recovery in yeast

10.1101/466797 ◽

2018 ◽

Author(s):

Matthew M. Crane ◽

Adam E. Russell ◽

Brent J. Schafer ◽

Mung Gi Hong ◽

Joslyn E. Goings ◽

...

Keyword(s):

Cell Cycle ◽

Genomic Instability ◽

Mother Cell ◽

Genome Instability ◽

Retrograde Transport ◽

Cell Cycle Checkpoints ◽

Control Mechanisms ◽

Cycle Arrest ◽

Single Cell Imaging ◽

Age Related

AbstractGenome instability is a hallmark of aging and contributes to age-related disorders such as progeria, cancer, and Alzheimer’s disease. In particular, nuclear quality control mechanisms and cell cycle checkpoints have generally been studied in young cells and animals where they function optimally, and where genomic instability is low. Here, we use single cell imaging to study the consequences of increased genomic instability during aging, and identify striking age-associated genome missegregation events. During these events the majority of mother cell chromatin, and often both spindle poles, are mistakenly sent to the daughter cell. This breakdown in mitotic fidelity is accompanied by a transient cell cycle arrest that can persist for many hours, as cells engage a retrograde transport mechanism to return chromosomes to the mother cell. The repetitive ribosomal DNA (rDNA) has been previously identified as being highly vulnerable to age-related replication stress and genomic instability, and we present several lines of evidence supporting a model whereby expansion of rDNA during aging results in nucleolar breakdown and competition for limited nucleosomes, thereby increasing risk of catastrophic genome missegregation.

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Effects of oriC relocation on control of replication initiation in Bacillus subtilis

Microbiology ◽

10.1099/mic.0.030080-0 ◽

2009 ◽

Vol 155 (9) ◽

pp. 3070-3082 ◽

Cited By ~ 4

Author(s):

Shigeki Moriya ◽

Yoshikazu Kawai ◽

Sakiko Kaji ◽

Adrian Smith ◽

Elizabeth J. Harry ◽

...

Keyword(s):

Cell Cycle ◽

Bacillus Subtilis ◽

Dna Replication ◽

Negative Control ◽

Replication Initiation ◽

Control Mechanisms ◽

Bacterial Cells ◽

Wild Type ◽

Dna Replication Initiation ◽

In The Wild

In bacteria, DNA replication initiation is tightly regulated in order to coordinate chromosome replication with cell growth. In Escherichia coli, positive factors and negative regulatory mechanisms playing important roles in the strict control of DNA replication initiation have been reported. However, it remains unclear how bacterial cells recognize the right time for replication initiation during the cell cycle. In the Gram-positive bacterium Bacillus subtilis, much less is known about the regulation of replication initiation, specifically, regarding negative control mechanisms which ensure replication initiation only once per cell cycle. Here we report that replication initiation was greatly enhanced in strains that had the origin of replication (oriC) relocated to various loci on the chromosome. When oriC was relocated to new loci further than 250 kb counterclockwise from the native locus, replication initiation became asynchronous and earlier than in the wild-type cells. In two oriC-relocated strains (oriC at argG or pnbA, 25 ° or 30 ° on the 36 ° chromosome map, respectively), DnaA levels were higher than in the wild-type but not enough to cause earlier initiation of replication. Our results suggest that the initiation capacity of replication is accumulated well before the actual time of initiation, and its release may be suppressed by a unique DNA structure formed near the native oriC locus.

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Role of the repressor Oaf3p in the recruitment of transcription factors and chromatin dynamics during the oleate response

Biochemical Journal ◽

10.1042/bj20121029 ◽

2012 ◽

Vol 449 (2) ◽

pp. 507-517 ◽

Cited By ~ 1

Author(s):

Yakun Wan ◽

Christina E. Arens ◽

Steven Wang ◽

Xiao Zuo ◽

Ya Zhuo ◽

...

Keyword(s):

Fatty Acid ◽

Cell Function ◽

Transcriptional Regulators ◽

Control Mechanisms ◽

Multiple Control ◽

Mrna Accumulation ◽

Chromatin Dynamics ◽

Nucleosome Structure ◽

In The Wild

Cellular responses to environmental stimuli are mediated by the co-ordinated activity of multiple control mechanisms, which result in the dynamics of cell function. Communication between different levels of regulation is central for this adaptability. The present study focuses on the interplay between transcriptional regulators and chromatin modifiers to co-operatively regulate transcription in response to a fatty acid stimulus. The genes involved in the β-oxidation of fatty acids are highly induced in response to fatty acid exposure by four gene-specific transcriptional regulators, Oaf (oleate-activated transcription factor) 1p, Pip2p (peroxisome induction pathway 2), Oaf3p and Adr1p (alcohol dehydrogenase regulator 1). In the present study, we examine the interplay of these factors with Htz1p (histone variant H2A.Z) in regulating POT1 (peroxisomal oxoacyl thiolase 1) encoding peroxisomal thiolase and PIP2 encoding the autoregulatory oleate-specific transcriptional activator. Temporal resolution of ChIP (chromatin immunoprecipitation) data indicates that Htz1p is required for the timely removal of the transcriptional repressor Oaf3p during oleate induction. Adr1p plays an important role in the assembly of Htz1p-containing nucleosomes on the POT1 and PIP2 promoters. We also investigated the function of the uncharacterized transcriptional inhibitor Oaf3p. Deletion of OAF3 led to faster POT1 mRNA accumulation than in the wild-type. Most impressively, a highly protected nucleosome structure on the POT1 promoter during activation was observed in the OAF3 mutant cells in response to oleate induction.

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Mutations in DNA Replication Genes Reduce Yeast Life Span

Molecular and Cellular Biology ◽

10.1128/mcb.22.12.4136-4146.2002 ◽

2002 ◽

Vol 22 (12) ◽

pp. 4136-4146 ◽

Cited By ~ 49

Author(s):

Laura L. Mays Hoopes ◽

Martin Budd ◽

Wonchae Choe ◽

Tao Weitao ◽

Judith L. Campbell

Keyword(s):

Dna Replication ◽

Life Span ◽

Genomic Instability ◽

Replicative Senescence ◽

Premature Aging ◽

Wild Type ◽

Cell Cycle Time ◽

Replicative Stress ◽

Age Related ◽

In The Wild

ABSTRACT Surprisingly, the contribution of defects in DNA replication to the determination of yeast life span has never been directly investigated. We show that a replicative yeast helicase/nuclease, encoded by DNA2 and a member of the same helicase subfamily as the RecQ helicases, is required for normal life span. All of the phenotypes of old wild-type cells, for example, extended cell cycle time, age-related transcriptional silencing defects, and nucleolar reorganization, occur after fewer generations in dna2 mutants than in the wild type. In addition, the life span of dna2 mutants is extended by expression of an additional copy of SIR2 or by deletion of FOB1, which also increase wild-type life span. The ribosomal DNA locus and the nucleolus seem to be particularly sensitive to defects in dna2 mutants, although in dna2 mutants extrachromosomal ribosomal circles do not accumulate during the aging of a mother cell. Several other replication mutations, such as rad27Δ, encoding the FEN-1 nuclease involved in several aspects of genomic stability, also show premature aging. We propose that replication fork failure due to spontaneous, endogenous DNA damage and attendant genomic instability may contribute to replicative senescence. This may imply that the genomic instability, segmental premature aging symptoms, and cancer predisposition associated with the human RecQ helicase diseases, such as Werner, Bloom, and Rothmund-Thomson syndromes, are also related to replicative stress.

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Freeze-substituted fungal cells of Nectria haematococca: A comparison of the macroconidial walls of the adhesion-competent wild type with an adhesion-reduced mutant

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100160996 ◽

1990 ◽

Vol 48 (3) ◽

pp. 688-689

Author(s):

Thecan Caesar-Ton That ◽

Lynn Epstein

Keyword(s):

Freeze Substitution ◽

Uranyl Acetate ◽

Wild Type ◽

Nectria Haematococca ◽

Fruit Extract ◽

Dialysis Tubing ◽

Tube Emergence ◽

Contrast Microscopy ◽

In The Wild ◽

Freeze Damage

Nectria haematococca mating population I (anamorph, Fusarium solani) macroconidia attach to its host (squash) and non-host surfaces prior to germ tube emergence. The macroconidia become adhesive after a brief period of protein synthesis. Recently, Hickman et al. (1989) isolated N. haematococca adhesion-reduced mutants. Using freeze substitution, we compared the development of the macroconidial wall in the wild type in comparison to one of the mutants, LEI.Macroconidia were harvested at 1C, washed by centrifugation, resuspended in a dilute zucchini fruit extract and incubated from 0 - 5 h. During the incubation period, wild type macroconidia attached to uncoated dialysis tubing. Mutant macroconidia did not attach and were collected on poly-L-lysine coated dialysis tubing just prior to freezing. Conidia on the tubing were frozen in liquid propane at 191 - 193C, substituted in acetone with 2% OsO4 and 0.05% uranyl acetate, washed with acetone, and flat-embedded in Epon-Araldite. Using phase contrast microscopy at 1000X, cells without freeze damage were selected, remounted, sectioned and post-stained sequentially with 1% Ba(MnO4)2 2% uranyl acetate and Reynold’s lead citrate. At least 30 cells/treatment were examined.

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