Linked Life Data

6156810

Source:http://linkedlifedata.com/resource/pubmed/id/6156810

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1980-10-27
pubmed:abstractText
The organization of DNA in the mitotic metaphase and polytene chromosomes of the fungus gnat, Sciara coprophila, has been studied using base-specific DNA ligands, including anti-nucleoside antibodies. The DNA of metaphase and polytene chromosomes reacts with AT-specific probes (quinacrine, DAPI, Hoechst 33258 and anti-adenosine) and to a somewhat lesser extent with GC-specific probes (mithramycin, chromomycin A3 and anti-cytidine). In virtually every band of the polytene chromosomes chromomycin A3 fluorescence is almost totally quenched by counterstaining with the AT-specific ligand methyl green. This indicates that GC base pairs in most bands are closely interspersed with AT base pairs. The only exceptions are band IV-8A3 and the nucleolus organizer on the X. In contrast, quinacrine and DAPI fluorescence in every band is only slightly quenched by counterstaining with the GC-specific ligand actinomycin D. Thus, each band contains a moderate proportion of AT-rich DNA sequences with few interspersed GC base pairs. - The C-bands in mitotic and polytene chromosomes can be visualized by Giemsa staining after differential extraction of DNA and those in polytene chromosomes by the use of base-specific fluorochromes or antibodies without prior extraction of DNA. C-bands are located in the centromeric region of every chromosome, and the telomeric region of some. The C-bands in the polytene chromosomes contain AT-rich DNA sequences without closely interspered GC base pairs and lack relatively GC-rich sequences. However, one C-band in the centromeric region of chromosome IV contains relatively GC-rich sequences with closely interspersed AT base pairs. - C-bands make up less than 1% of polytene chromosomes compared to nearly 20% of mitotic metaphase chromosomes. The C-bands in polytene chromosomes are detectable with AT-specific or GC-specific probes while those in metaphase chromosomes are not. Thus, during polytenization there is selective replication of highly At-rich and relatively GC-rich sequences and underreplication of the remainder of the DNA sequences in the constitutive heterochromatin.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0009-5915
pubmed:author
pubmed:issnType
Print
pubmed:volume
79
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
293-314
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1980
pubmed:articleTitle
The organization of DNA in the mitotic and polytene chromosomes of Sciara corprophila.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.