These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Competence for deoxyribonucleic acid uptake and deoxyribonuclease action external to cells in the genetic transformation of Diplococcus pneumoniae.
    Author: Lacks S, Greenberg B.
    Journal: J Bacteriol; 1973 Apr; 114(1):152-63. PubMed ID: 4144589.
    Abstract:
    A mutant of Diplococcus pneumoniae that apparently does not require activator can become competent for uptake of deoxyribonucleic acid (DNA) when grown in dilute cultures or in the presence of trypsin. Development of competence in both mutant and wild strains is temperature dependent, being 10-fold greater at 30 C than at 37 C. Induction of competence on a shift from 37 to 30 C requires protein synthesis and the presence of Mg(2+) and Ca(2+); uptake of DNA does not require protein synthesis. Competence decays exponentially at higher temperatures. As well as taking up DNA, competent cells release oligonucleotide fragments of donor DNA in the medium external to the cells. Normal strains release fragments comparable in amount to the DNA taken up; but, in a mutant selected for inability to degrade DNA in agar, the amount of fragments formed external to the cells is only 40% of DNA uptake. Requirements for external deoxyribonuclease action are identical to those for DNA uptake: prior development of competence and the presence during treatment with DNA of Mg(2+) ions and a source of energy.
    [Abstract] [Full Text] [Related] [New Search]