Satellite DNA and cytogenetic evolution: molecular aspects and implications for man. [Kangaroo rats]
Simple, highly reiterated DNA sequences, often observed in density gradients as satellite DNAs, exist in condensed heterochromatin. This material is predominantly located at chromosomal centromeres, occasionally at telomeres, or intercalated within arms; in a few species it occupies entire chromosome arms. Satellite DNAs are a highly variable component of the genome of most higher eukaryotes, but their functions have remained speculative. The genus of kangaroo rats (Dipodomys) exhibits remarkable interspecies variations in content of three satellite DNAs, consisting of simple sequences 3 to 10 base pairs long, and in species karyotypes. A broad range of diploid-DNA content is correlated with satellite-DNA content. The latter is correlated positively with predominance of biarmed over uniarmed chromosomes (high fundamental number FN) and inversely with two anatomical indices (leg-bone-length ratios) of specialization for the jumping gait. Karyotypic variation is achieved via chromosomal rearrangements, e.g., Robertsonian fusion, C-band heteromorphism, and pericentric inversion. Environmental adaptation is achieved, in part, by reassortment of gene-linkage groups and regulatory controls as a result of the chromosomal rearrangements. The foregoing relationships led to the postulation that highly reiterated DNA sequences play a supragenic, global role in environmental adaptation and the evolution of new species.
- Research Organization:
- California Univ., Livermore (USA). Lawrence Livermore Lab.
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 7324032
- Report Number(s):
- UCRL-79120; CONF-770308-3
- Resource Relation:
- Conference: ICN-UCLA symposium on molecular and cellular biology, Keystone, CO, USA, 7 Mar 1977
- Country of Publication:
- United States
- Language:
- English
Similar Records
Molecular cytogenetic characterization of 17 rob(13q14q) Robertsonian translocations by FISH, narrowing the region containing the breakpoints
Cytogenetic and molecular studies on a recombinant human X chromosome: implications for the spreading of X chromosome inactivation
Related Subjects
DNA REPLICATION
GENETIC VARIABILITY
RODENTS
BIOLOGICAL EVOLUTION
GENOME MUTATIONS
CHROMOSOMES
CYTOLOGY
GENETICS
MOLECULAR BIOLOGY
WILD ANIMALS
ANIMALS
BIOLOGICAL VARIABILITY
BIOLOGY
MAMMALS
MUTATIONS
NUCLEIC ACID REPLICATION
VERTEBRATES
550400* - Genetics
550300 - Cytology