Linked Life Data

3678610

Source:http://linkedlifedata.com/resource/pubmed/id/3678610

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1987-12-30
pubmed:abstractText
Autoradiography has been used to confirm and to extend previous microspectrophotometric studies (Doerder and DeBault, 1975) on the timing of DNA synthesis during conjugation in Tetrahymena thermophila. The majority of DNA synthesis occurs at the expected periods preceding gamete formation and the two postzygotic divisions and during macronuclear development. DNA in new macronuclei is endoreplicated in an extremely discontinuous fashion. Under starvation conditions, the first endoreplication (2C to 4C) occurs immediately after the second postzygotic division when both new macronuclei and new micronuclei replicate. The second endoreplication (4C to 8C) does not occur until after separation of conjugants. If mating cells are kept under prolonged starvation conditions (20-24 hr), refeeding induces a partially synchronous division, after which an unexpectedly high percentage of cells incorporate tritiated thymidine into both macro- and micronuclei. Two previously undescribed periods of DNA synthesis were observed in the micronuclei of conjugating Tetrahymena. The first occurs during the early stages of meiotic prophase, before full crescent elongation. The second takes place in an extended period corresponding to macronuclear anlagen development, before conjugants have separated. CsCl gradient analyses indicate that, in micronuclear fractions, only main band DNA is being synthesized in both of these periods. However, in macronuclear fractions from both stages, a significant fraction (approximately 20%) of the DNA being synthesized has the buoyant density of ribosomal DNA. The finding that macro- and micronuclear DNA can be synthesized simultaneously in a single cell, both during conjugation and after refeeding starved exconjugants, raises interesting questions of how macro- or micronuclear-specific histones are targeted to the appropriate nuclei.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0012-1606
pubmed:author
pubmed:issnType
Print
pubmed:volume
124
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
469-80
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1987
pubmed:articleTitle
Scheduled and unscheduled DNA synthesis during development in conjugating Tetrahymena.
pubmed:affiliation
Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, Houston, Texas 77030.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.