Synchronous Growth and Plastid Replication in the Naturally Wall-less Alga <i>Olisthodiscus luteus</i>

Cattolico, Rose Ann; Boothroyd, John C.; Gibbs, Sarah P.

doi:10.1104/pp.57.4.497

Cited by 66 publications

(30 citation statements)

References 29 publications

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“…Unless otherwise indicated, illumination (Westinghouse cool-white bulbs) was 612 ft-c at the culture surface. All cell counts, chloroplast counts, and DNA extractions were made with cells harvested between hours 6 to 8 of the light portion of the synchronous growth cycle when no cell division, chloroplast replication, or nuclear DNA synthesis was taking place (9 chloroplasts/cell within both the logarithmic and linear Olisthodiscus populations is not normally distributed. A positive asymmetry (skewness) and leptokurtosis (flat peakedness) are evident.…”

Section: Methodsmentioning

confidence: 99%

“…This organism contains many small plastids which replicate at a defined period of the synchronous cell cycle (9) changes in the growth regime of the cell. In addition, the chloroplast complement of these wall-less cells may be easily and stringently monitored.…”

mentioning

confidence: 99%

“…The unicellular alga Olisthodiscus luteus (9) was chosen as the test system for these studies. This organism contains many small plastids which replicate at a defined period of the synchronous cell cycle (9) changes in the growth regime of the cell.…”

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confidence: 99%

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Variation in Plastid Number

Cattolico¹

1978

Plant Physiol.

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Changes in the physiological state of the multiplastidic alga OHstbodiscus luteus result in a shift in chloroplast complement from 33 to 21 plastids. The effect of this induced change in organelle complement on nuclear and chloroplast DNA levels has been analyzed. Data suggest that the absolute amount of chloroplast and nuclear DNA found within a cell remains constant but that the amount of chloroplast DNA per plastid is inversely proportional to the number of chloroplasts to which that DNA must be distributed.Eukaryotic cell function is dependent upon a highly refined metabolic coordination between the nucleus and other compartmentalized cellular structures. Of the many organelles present within the cell, chloroplasts probably rank highest in biochemical and structural complexity (6). Light availability (25,30), light quality (23), temperature (25), the presence of plant hormones and specific carbon compounds (4) or the entrance of the organism into a specific differentiation sequence (7) may induce a cell to vary its chloroplast complement significantly. It has been known for some time (1) that nuclear gene products are necessary for organelle maintenance. Recent data (13, 26) obtained by investigators attempting to describe the specific coding function of chloroplast DNA indicate that the per cent chloroplast genome transcribed may change during different phases of cell growth and development. It has been reported (12, 27) that the total amount of chloroplast DNA/cell may shift in response to conditions of cellular maintenance of differentiation. Although a positive correlation has been postulated (8) to exist in higher plant systems between an increase in chloroplast number and a maintenance of nuclear DNA synthesis, little is known of the relationship between plastid number and organelle DNA levels. Feedback loops must exist between the nuclear and organelle genome and the macromolecular communication effected by these loops is, no doubt, of primary importance both in the regulation of organelle development and in the determination of cellular replication.Measurement of the relationship between plastid number, chloroplast DNA complement, and nuclear DNA content should provide background data of critical importance to studies concerned with the elucidation of the macromolecular interaction of genome and plastome in organelle biogenesis.The unicellular alga Olisthodiscus luteus (9) was chosen as the test system for these studies. This organism contains many small plastids which replicate at a defined period of the synchronous cell cycle (9) and plastid

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Section: Methodsmentioning

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Variation in Plastid Number

Cattolico¹

1978

Plant Physiol.

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“…Two studies gave preliminary indication that the amount of ctDNA per organelle could vary within a multiplastidic cell. Panacium maximum was shown (29) to contain 50 ctDNA molecules in bundle sheath chloroplasts but only 20 in mesophyll plastids, and it was reported (19) that Narcissus pseudonarcissus leaf chloroplasts contain 50 ctDNA copies, whereas flower chromoplasts contain only 8 ctDNA copies. The fact that ctDNA synthesis and chloroplast division are two separable events (see ref.…”

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confidence: 99%

“…Cultures were sampled in the logarithmic or the linear growth phase at L6 of the synchronous cell cycle when neither cell nor chloroplast division is taking place (8). When necessary, the sample was centrifuged at 1,500 rpm for 2 min using a clinical table top centrifuge to concentrate the cells to approximately 106 cells/ml.…”

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Kinetic Complexity, Homogeneity, and Copy Number of Chloroplast DNA from the Marine Alga Olisthodiscus luteus

Ersland¹,

Aldrich²,

Cattolico³

1981

Plant Physiol.

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The kinetic complexity of chloroplast DNA isolated from the chromophytic alga Olistwdiscw Iutes has been determined. Using optical reassociaton ques, it was shown that the plastid DNA of this alga reacted as a single co eat with a second order rate constant of 4.1 molar 1aIdsecond' I (Cot12 0.24molar second)undercondtions equivalent to 180 miliar Na' and 60°C. Given alga, Olisthodiscus luteus provided an excellent system in which DNA ploidy variation response could be analyzed within a nondifferentiating cell. Using this naturally wall-less (8) test system, wherein precise chloroplast counts could be made, it was demonstrated (7) that the amount of ctDNA present per chloroplast was inversely related to the chloroplast complement of the cell. This result conclusively demonstrated that the chloroplasts of an organism could be significantly plastic with respect to DNA complement. The observation made in the Olisthodiscus system has now been confirmed in higher plants. Expanding spinach (27) and maturing pea leaves (18) were each shown to exhibit a similar inverse relationship between organelle DNA level and organelle number. Moreover, since the genome sizes of the pea and spinach ctDNA were known, it was possible to calculate the number of DNA molecules present per plastid. Although the elegant studies on higher plant systems represented a major advance in our understanding of the changes in organelle DNA ploidy levels which occur during different phases of plant growth and differentiation, difficulties of cell morphology (for example, the presence of an intractable cell wall) necessitated protoplast isolation (18) or the use of Chl content (27) in ascertaining organelle number. In addition, complexity of these higher plant systems dictates that a measurement of organelle number reflects a change within a population of differing cell types. Thus, large variations in organelle counts (18) per tissue sample are often obtained.A multiplastidic unicellular alga would represent an ideal system to monitor DNA ploidy changes which occur when the organism is subject to varying conditions of growth and/or development. The Euglena system which has been extensively analyzed shows (24) a dramatic change in the number of total ctDNA molecules per cell when cultures are maintained under heterotrophic, autotrophic, or mixotrophic growth conditions. Studies of Lyman and co-workers (personal communication) have shown that the spectral quality of light significantly influences the levels of ctDNA within Euglena. Cultures maintained under blue light show higher levels of ctDNA per cell than those cultures maintained under a red light regime. Unfortunately, no information on plastid complement which is known to shift (22) in response to the physiological state ofthe Euglena cell were done in conjunction with either of these studies. The macro-unicellular alga, Acetabulana, gives an exciting clue to the extremes ofctDNA complement potential within the plastid. By use of the fluorescent dye DAPI, Coleman (11) has demonstrated ...

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Composition, diversity, and activity of aerobic ammonia‐oxidizing Bacteria and Archaea in the intertidal sands of a grand strand South Carolina beach

Taylor

Kurtz

2020

MicrobiologyOpen

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Aerobic ammonia oxidation to nitrite has been established as an important ecosystem process in regulating the level of nitrogen in marine ecosystems. This process is carried out by ammonia‐oxidizing bacteria (AOB) within the classes Betaproteobacteria and Gammaproteobacteria and ammonia‐oxidizing Archaea (AOA) from the phylum Thaumarchaeota, and the latter of which has been established as more prevalent in marine systems. This study investigated the presence, abundance, and activity of these groups of microbes at a beach near Springmaid Pier in Myrtle Beach, South Carolina, through the implementation of next generation sequencing, quantitative PCR (qPCR), and microcosm experiments to monitor activity. Sequencing analysis revealed a diverse community of ammonia‐oxidizing microbes dominated by AOA classified within the family Nitrosopumilaceae, and qPCR revealed the abundance of AOA amoA genes over AOB by at least an order of magnitude in most samples. Microcosm studies indicate that the rates of potential ammonia oxidation in these communities satisfy Michaelis–Menten substrate kinetics and this process is more active at temperatures corresponding to summer months than winter. Potential rates in AOA medium were higher than that of AOB medium, indicating a potentially greater contribution of AOA to this process in this environment. In conclusion, this study provides further evidence of the dominance of AOA in these environments compared with AOB and highlights the overall efficiency of this process at turning over excess ammonium that may be present in these environments.

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Synchronous Growth and Plastid Replication in the Naturally Wall-less Alga Olisthodiscus luteus

Cited by 66 publications

References 29 publications

Variation in Plastid Number

Variation in Plastid Number

Kinetic Complexity, Homogeneity, and Copy Number of Chloroplast DNA from the Marine Alga Olisthodiscus luteus

Composition, diversity, and activity of aerobic ammonia‐oxidizing Bacteria and Archaea in the intertidal sands of a grand strand South Carolina beach

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