ABSTRACT
In Drosophila, sequences anchoring the DNA molecule to the scaffold (SARs) and sequences able to replicate autonomously (ARSs) had been shown to comap on an 835-kb DNA fragment (Brun et al. (1990) Mol. Cell. Biol. 10, 5455-5463). To investigate the question of whether this comapping results from the coincidental recruitment of SARs and ARSs in A,T-rich regions, A,T-rich regions of the 835-kb DNA fragment have been identified by restriction analysis with enzymes recognizing motifs made exclusively of A and T. Within the limits of sensitivity of this approach, the obtained data favor the idea of a noncoincidental recruitment: obviously a SAR and an ARS subpopulation are preferentially localized in the A,T-rich regions, but not every A,T-rich region displays a SAR activity, or an ARS activity, or both, nor are all SARs or ARSs localized in the A,T-rich regions. In addition, the data support the idea that a statistical assessment of base composition using restriction analysis might be developed into a general useful approach to genome organization.
Subject(s)
DNA Replication , DNA/chemistry , DNA/genetics , Drosophila/genetics , Adenine/analysis , Animals , Base Sequence , DNA/metabolism , DNA Restriction Enzymes/metabolism , Genome , Molecular Sequence Data , Restriction Mapping , Substrate Specificity , Thymine/analysisABSTRACT
Structured as a data base and associated with data analysis tools, ACNUC allows both on-line access to a central computer and local exploitation of published nucleotide sequences. Its data retrieval capabilities seem to be presently the most powerful available.
Subject(s)
Base Sequence , Information Systems , Nucleic AcidsABSTRACT
The nucleic acid sequence bank now contains 161 mRNAs, 43 new genes are added. One sequence, that of B. mori fibroin, is dropped due to uncertainty on the starting point for translation. Frequencies of all codons are given for each gene added and for each genome type in the total bank. A new series of correspondence analyses on codon use is presented, substantiating the genome hypothesis. Internal regulation of mRNA expression by different third base choices between quartet and duet codons is proposed for bacterial genes.
