Related Experiment Videos
Variation in density and transformation potential in deoxyribonucleic acid from Neisseria meningitidis
Abstract:
Jyssum, Kaare (University of Oslo, Oslo, Norway), and Sidsel Jyssum. Variation in density and transformation potential in deoxyribonucleic acid from Neisseria meningitidis. J. Bacteriol. 90:1513-1519. 1965.-Three variants of Neisseria meningitidis have been examined with regard to competence. One is the genetically competent M1-12 his(-)cp(+), the second is the genetically incompetent M1-12 his(-)cp(-) which does not revert to competence, and the third is the incompetent mutant M1-18 his(-)gly(-)(cp) which reverts to competence. An examination of the relation between the deoxyribonucleic acid (DNA) and protein contents indicates the existence of more DNA in strain M1-12 his(-)cp(+) than in strain M1-12 his(-)cp(-). DNA prepared from the three strains was examined by density gradient centrifugation. The distribution of DNA in the gradients was unimodal. No significant differences could be observed between the distribution curves obtained from the three test strains. When the distribution in the gradients of transformation potential corresponding to five biochemical markers was measured, a pronounced difference was found among the three test strains. The distribution of the markers in the gradient from strain M1-12 his(-)cp(-) was unimodal. In the DNA from strain M1-18 his(-)gly(-)(cp), all the markers examined showed bipartite distribution curves with low relative specific transforming activity, corresponding to an area near the middle of the DNA distribution. The strain M1-12 his(-)cp(+) showed a similar bipartite distribution of four biochemical markers, whereas the marker pro had a very high relative specific transforming activity in the area where the other markers tested had a reduced activity. The nature of the DNA with reduced transformation potential which seems to be present in strains M1-12 his(-)cp(+) and M1-18 his(-)gly(-)(cp) is discussed in relation to previous observations. The possibility has been presented that the cp factor in N. meningitidis may be a true episome.
Insights
This study examined deoxyribonucleic acid (DNA) from Neisseria meningitidis variants. Genetically competent strains showed unique DNA transformation potentials, suggesting a potential episome factor.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Neisseria meningitidis exhibits variations in genetic competence, influencing its transformation potential.
- Understanding the relationship between DNA content and transformation is crucial for bacterial genetics.
Purpose of the Study:
- To investigate the variation in deoxyribonucleic acid (DNA) density and transformation potential among different Neisseria meningitidis strains.
- To explore the characteristics of DNA associated with genetic competence and transformation in N. meningitidis.
Main Methods:
- Density gradient centrifugation was employed to analyze the distribution of DNA from three N. meningitidis strains.
- Transformation potential of specific biochemical markers was measured across density gradients.
Main Results:
- While DNA distribution was unimodal across all strains, transformation potential varied significantly.
- Competent strains displayed bipartite distribution curves for transformation potential, indicating DNA with reduced activity.
- One competent strain showed exceptionally high transformation activity for a specific marker (pro) in contrast to others.
Conclusions:
- The observed differences in transformation potential suggest unique DNA characteristics in competent N. meningitidis strains.
- The findings support the hypothesis that the competence (cp) factor in N. meningitidis may function as an episome.