Chloroplast DNA: Physical and Genetic Studies

Sager, Ruth; Schlanger, Gladys

doi:10.1007/978-1-4615-7148-3_12

Cited by 10 publications

(5 citation statements)

References 125 publications

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“…1) (Fig. 3 upper) the percentage of total label in cytosine decreased substantially in the interval between 6 and 24 hr after mating (Table 1), much of it reappearing in thymine. When the paternal cells were prelabeled (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The data are from a second preparative CsCl gradient containing chloroplast DNA pooled from the first gradient in which a small amount of nuclear DNA was present. By utilizing the absorbance peaks of nuclear and chloroplast DNAs as reference points and assuming a linear gradient, we have estimated a bouyant density decrease of about [6][7][8][9][10] mg/cm3 in the tritiated chloroplast DNA of maternal origin. The homologous DNA from the paternal parent was largely degraded within 6 hr after zygote formation.…”

Section: Resultsmentioning

confidence: 99%

“…1, in which the chloroplast DNA of each parent was prelabeled by growth in medium containing [3H]thymidine. Each parent was then mated to unlabeled cells of the opposite mating type in a pair of reciprocal crosses, and chloroplast DNA was extracted from zygotes immediately after mating (To) and after 6 and 24 hr. The data are from a second preparative CsCl gradient containing chloroplast DNA pooled from the first gradient in which a small amount of nuclear DNA was present.…”

Section: Resultsmentioning

confidence: 99%

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Role of methylation in the modification and restriction of chloroplast DNA in Chlamydomonas.

Burton¹,

Grabowy²,

Sager³

1979

Proc. Natl. Acad. Sci. U.S.A.

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The different metabolic paths followed by homologous chloroplast DNAs of maternal and paternal origins in zygotes of Chlamydomonas were examined by prelabeling parental cells, before mating them, with [3H]adenine, [3Hlthy-midine, and [3Hldeoxycytidine. Within 6 hr after mating, maternal chloroplast DNA was extensively methylated to 5-methylcytosine and its bouyant density decreased. Paternal chloroplast DNA was largely degraded. Some radioactivity from deoxycytidine of maternal origin reappeared in thymine, and residual paternal DNA contained radioactivitv in a base tentatively identified as uracil. These results conirm and extend our previous findings and support our hypothesis that modification (methylation) and restriction enzymes determine maternal inheritance of chloroplast DNA and that the two parental DNAs have different metabolic fates within the zygote. In 1972, it was postulated (1) that a modification-restriction mechanism analogous to that responsible for host-range restriction of bacteriophage (2) was the molecular basis of maternal inheritance of chloroplast genes in Chlamydomonas. This hypothesis was based upon the finding that chloroplast DNAs of male and female origins, indistinguishable in vegetative cells, follow different paths in the zygotes that form after gametic fusion (fertilization). Chloroplast DNA from the female parent persists in the zygote but is shifted to a lighter bouyant density, whereas that from the male is lost soon after zygote formation (1). Thus, the density shift could result from enzymatic modification of chloroplast DNA of female origin; and the loss of chloroplast DNA of male origin could result from attack by a restriction enzyme upon unmodified DNA molecules.The modification-restriction hypothesis was further supported by studies in which maternal transmission of chloroplast genes was converted to a biparental or paternal pattern by UV-irradiation of female gametes before mating (3), by various drug pretreatments (4), or by a mutant nuclear gene, mat-i (5).Complementing the genetic studies, in studies of radioisotope prelabeled chloroplast DNAs from zygotes after UV-irradiation and in crosses with mat-i it was found (6, 7) that chloroplast DNA of male origin was preserved in parallel with the genetic markers. These experiments demonstrate that the molecular pattern of inheritance of chloroplast DNA parallels that of chloroplast genes in Chlamydomonas (reviewed in refs. 8 and 9).In this paper, we report that the bouyant density decrease of zygotic chloroplast DNA occurs in concert with the extensive methylation of cytosine residues to form 5-methylcytosine and that a low level of methylation is already present in the gametic chloroplast DNA of female origin and is greatly increased in zygotes in which the genetic pattern of transmission is maternal. These results provide definite support for the modificationrestriction mechanism of non-Mendelian inheritance of chloroplast genes in Chlamydomonas.MATERIALS AND METHODS Cells and Media. The strains used-the wild...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Role of methylation in the modification and restriction of chloroplast DNA in Chlamydomonas.

Burton¹,

Grabowy²,

Sager³

1979

Proc. Natl. Acad. Sci. U.S.A.

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“…Since 1963, CsC1 gradient centrifugation has been used widely to identify and isolate chloroplast DNA from plants [95]. However, difficulties were encountered early in isolating the chloroplast DNA of higher plants because their buoyant densities were similar to those of the nuclear DNAs.…”

Section: Genome Structurementioning

confidence: 99%

“…The first method was that of standard genetic analysis. Chloroplast genes coding for ribosomal proteins in Chlamydomonas and fraction 1 pro-teins in tobacco were analyzed by this method [95]. Analysis of the plastome mutants of Antirrhinum and Pelargonium suggested that some components of the thylakoid membrane are encoded in the chloroplast genome [46].…”

Section: Gene Structurementioning

confidence: 99%

The chloroplast genome

1992

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History of chloroplast genomics

Sugiura

Discoveries in Photosynthesis

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The presence of chloroplast DNA was established in 1963. With the development of recombinant DNA technologies, chloroplast DNA was selected as one of the first candidates for genome sequencing. The first physical map was reported for maize chloroplasts in 1976. As tobacco has been popular as an experimental system, tobacco chloroplast DNA has been extensively analyzed and the complete nucleotide sequence was established in 1986. This sequencing and the availability of tobacco chloroplast transformation techniques and of in vitro expression systems have formed the basis of an ongoing functional genomics program.

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Chloroplast DNA: Physical and Genetic Studies

Cited by 10 publications

References 125 publications

Role of methylation in the modification and restriction of chloroplast DNA in Chlamydomonas.

Role of methylation in the modification and restriction of chloroplast DNA in Chlamydomonas.

The chloroplast genome

History of chloroplast genomics

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