Analysis of Mycoplasma hyorhinis genome by use of restriction endonucleases and by electron microscopy

Abstract

The chromosome of M. hyorhinis was analyzed by using different restriction endonucleases and EM. Restriction enzymes BstEII, XhoI and SacI are the enzymes of choice for analysis and characterization of M. hyorhinis. The band resulting form digestion of M. hyorhinis DNA with BstEII had apparent MW ranging from 1.2 .times. 106 to 75 .times. 106. The apparent total MW of DNA was calculated from the MW of the individual bands and found to be 251 .times. 106. EM contour length measurements of the largest DNA fragments verified the MW values calculated from gel analysis. EM contour length measurements of intact DNA of M. hyorhinis revealed a MW of 5.4 .+-. 5 .times. 108. The discrepancy between the values of MW of M. hyorhinis DNA as determined by restriction enzyme analysis and contour length measurement is based on the fact that some of the DNA fragments which migrate as an apparent single band in the agarose gel really are double or multiple DNA fragments.