Changes in Plastid DNA Content during the Life Cycle of the Hornwort Anthoceros punctatus L.

Cells with polyploid nuclei are generally larger than cells of the same organism or species with nonpolyploid nuclei. However, no such change of cell size with ploidy level is observed in those red algae which alternate isomorphic haploid with diploid generations. The results of this investigation reveal the explanation. Nuclear DNA content and other parameters were measured in cells of the filamentous red alga Griffithsia pacifica. Nuclei of the diploid generation contain twice the DNA content of those of the haploid generation. However, all cells except newly formed reproductive cells are multinucleate. The nuclei are arranged in a nearly perfect hexagonal array just beneath the cell surface. When homologous cells of the two generations are compared, although the cell size is nearly identical, each nucleus of the diploid cell is surrounded by a region of cytoplasm (a "domain") nearly twice that surrounding a haploid nucleus. Cytoplasmic domains associated with a diploid nucleus contain twice the number of plastids, and consequently twice the amount of plastid DNA, than is associated with the domain of a haploid nucleus. Thus, doubling of ploidy is reflected in doubling of the size and organelle content of the domain associated with each nucleus. However, cell size does not differ between homologous cells of the two generations, because total nuclear DNA (sum of the DNA in all nuclei in a cell) per cell does not differ. This is the solution to the cytological paradox of isomorphy.

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Nuclear Volumes and Dna Content of Three Stages in the Life Cycle of Armillaria Bulbosa

Mycologia ◽

10.1080/00275514.1986.12025359 ◽

1986 ◽

Vol 78 (6) ◽

pp. 967-968 ◽

Cited By ~ 1

Author(s):

Diane Cope Peabody ◽

Robert B. Peabody

Keyword(s):

Life Cycle ◽

Dna Content ◽

Three Stages

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The Relationship between 2 C DNA Content, Life Cycle Type, Systematic Position and the Dynamics of DNA Endoreplication in Parenchyma Nuclei during Growth and Differentiation of Roots in some Dicotyledonous Herbaceous Species

Biochemie und Physiologie der Pflanzen ◽

10.1016/s0015-3796(83)80073-0 ◽

1983 ◽

Vol 178 (8) ◽

pp. 581-599 ◽

Cited By ~ 27

Author(s):

Maria J. Olszewska ◽

Regina Osiecka

Keyword(s):

Life Cycle ◽

Dna Content ◽

Systematic Position ◽

Herbaceous Species ◽

Dna Endoreplication ◽

The Relationship

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Age-associated change in macronuclear DNA content in Paramecium caudatum

Journal of Cell Science ◽

10.1242/jcs.54.1.137 ◽

1982 ◽

Vol 54 (1) ◽

pp. 137-147

Author(s):

Y. Takagi ◽

N. Kanazawa

Keyword(s):

Life Cycle ◽

Life Span ◽

Dna Content ◽

Tetrahymena Thermophila ◽

Relative Volume ◽

Paramecium Caudatum ◽

Unequal Distribution ◽

Equal Distribution ◽

Daughter Cells ◽

Initial Content

Macronuclear DNA content in Paramecium caudatum was found to be almost unchanged with a mean of about 400C during the earlier two-thirds of the life span in terms of the number of fissions and then it dropped rapidly to about one-fifth of the initial content. The age when rapid DNA decline occurred corresponded to that when the characteristics of senescence appeared. This decreasing pattern of macronuclear DNA content contrasted with earlier observations in P. tetraurelia, P. bursaria and Tetrahymena thermophila. The data suggested that in P. caudatum the distribution pattern of macronuclear DNA to daughter cells changed from an almost equal distribution in younger cells to an unequal distribution in older cells, while the relative volume of the macronucleus to the whole cell remained almost constant throughout the life cycle.

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Nuclear DNA content and chromosome numbers throughout the life cycle of the Colonia strain of the myxomycete, Physarum polycephalum

Journal of Cell Science ◽

10.1242/jcs.24.1.95 ◽

1977 ◽

Vol 24 (1) ◽

pp. 95-108

Author(s):

J. Mohberg

Keyword(s):

Lactic Acid ◽

Life Cycle ◽

Chromosome Number ◽

Dna Content ◽

Physarum Polycephalum ◽

Nuclear Dna ◽

Nuclear Dna Content ◽

S Phase ◽

Dna Analyses

Nuclear DNA content and ploidy have been determined at different stages of the life cycle of the Colonia strain of the myxomycete Physarum polycephalum. Analyses at the plasmodial stage showed that (a) Burton and Fuelgen DNA analyses agreed within 15% with strains which ranged from 0-6 to 3-6 pg of DNA per nucleus; (b) S-phase in Colonia is during the early part of interphase as in the Wisconsin strain; (c) in heterothallic and heterothallic × Colonia crossed strains there are 1-0-1-2 pg of DNA and 70 chromosomes per nucleus and in Colonia 0-6 pg of DNA and 40 chromosomes. Germinating spores of all strains contained one population of cells with about 0-5 pg of DNA and 40 chromosomes and another of larger cells with up to 2-5 pg of DNA and 200 chromosomes. The polyploid nuclei comprised 2–20% of the total in heterothallic strains, 2–65% in heterothallic × Colonia crosses and 25–75% in Colonia. A method was devised for making chromosome spreads of amoebae grown on bacterial lawns. Cells were first exposed to dilute formaldehyde at 26 degrees C for 30 min, then spread on slides with hot lactic acid and strained. Such spreads of CLd (Colonia) and RSD4 (heterothallic) amoebae both contained about 40 chromosomes. The data are consistent with the view that Colonia is haploid throughout its life cycle and that chromosome number is neither halved during sporulation nor doubled during plasmoidal formation. However, the possibility exists that an alternance of ploidy occurs by way of the few diploid nuclei present in the plasmodium.

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The Spoilage Yeast Zygosaccharomyces bailii Forms Mitotic Spores: a Screening Method for Haploidization

Applied and Environmental Microbiology ◽

10.1128/aem.69.1.649-653.2003 ◽

2003 ◽

Vol 69 (1) ◽

pp. 649-653 ◽

Cited By ~ 22

Author(s):

Fernando Rodrigues ◽

Paula Ludovico ◽

Maria João Sousa ◽

H. Yde Steensma ◽

Manuela Côrte-Real ◽

...

Keyword(s):

Life Cycle ◽

Dna Content ◽

Type Strain ◽

Mitotic Chromosome ◽

Molecular Genetic ◽

Screening Method ◽

Chromosome Loss ◽

Genetic Studies ◽

Zygosaccharomyces Bailii ◽

Spoilage Yeast

ABSTRACT Zygosaccharomyces bailii ISA 1307 and the type strain of this spoilage yeast show a diploid DNA content. Together with a rather peculiar life cycle in which mitotic but no meiotic spores appear to be formed, the diploid DNA content explains the observed difficulties in obtaining auxotrophic mutants. Mitotic chromosome loss induced by benomyl and selection on canavanine media resulted in three haploid strains of Z. bailii. This new set of Z. bailii strains allows the easy isolation of recessive mutants and is suitable for further molecular genetic studies.

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