Document Detail

Evolution by polyploidy in Amphibia: new insights.
MedLine Citation:
PMID:  9678330     Owner:  NLM     Status:  MEDLINE    
Polyploidy is an important mechanism of evolution in lower vertebrates, resulting in gene duplication and loci duplication evolving to diploidization. In polyploid anurans DNA is increased, but RNA and protein synthesis is kept at the same levels as in their diploid counterparts. Recent cytogenetic findings in Odontophrynus americanus show: (1) amphiplasty and asynchrony of the cell division cycle in 4n and (2) intra- and interindividual alterations of chromosome 4 morphology in 4n and 2n through breaks at secondary constrictions and at/or around the centromeres, followed by the appearance of changes of centromeres position, dicentrics, bisatellited chromosomes, precocious sister-chromatid segregation, and loss or unequal segregation of the chromosomes. This genome instability suggests the presence of chromosomal aberrations with chromodomain alterations at the centromeres affecting the mechanisms ensuring normal segregation of the chromatids in anaphase of mitosis and meiosis. Cell division asynchrony and chromosome abnormalities, novel findings in polyploids, are discussed respectively in function of gene activity and putative translocations producing polymorphisms in nucleolus organizers and secondary constrictions.
M L Beçak; W Beçak
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Review    
Journal Detail:
Title:  Cytogenetics and cell genetics     Volume:  80     ISSN:  0301-0171     ISO Abbreviation:  Cytogenet. Cell Genet.     Publication Date:  1998  
Date Detail:
Created Date:  1998-08-21     Completed Date:  1998-08-21     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0367735     Medline TA:  Cytogenet Cell Genet     Country:  SWITZERLAND    
Other Details:
Languages:  eng     Pagination:  28-33     Citation Subset:  IM    
Laboratório de Genética, Instituto Butantan, São Paulo, Brazil.
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MeSH Terms
Amphibians / genetics*
DNA Replication

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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