Cosntruction of the physical map of yeast（Saccharomyces cerevisiae）chromosome V^1

There are about 17 chromosomes in yeast Saccharomycescerevisiae.A middle sized chromosome,chromosome V,waschosen in this work for studying and constructing the physi-cal maps.Chromosome V from strain A364a was isolatedby pulsed-field gradient gel electrophoresis(PFGE).Gelslices containing chromosome V DNA were digestedwith two rare cutting enzymes,NotⅠand SfiⅠ,and three6-Nt recognizing enzymes,SmaⅠ,SstⅡ and ApaⅠ.Several strategies-partial or complete digestions,digestion with different sets of two enzymes,and hybrid-ization with cloned genetically mapped probes(CAN1,URA3,CEN5,PRO3,CHO1,SUP19,RAD51,RAD3)——were used to align the restriction fragments.There are 9,9,15,17,and 20 sites for NotⅠ,SfiⅠ,SmaⅠ,SstⅡ and ApaⅠrespectively in the map of the A364a chromosome V.Itstotal length was calculated to be 620 Kb(Kilo-bases).Thedistributions of the cutting sites for these five enzymesthrough the whole chromosome are not uniform.A comp-arison between the physical map and the genetic map wasalso made.

There are about 17 chromosomes in yeast Saccharomyces cerevisiae. A middle sized chromosome, chromosome V, was chosen in this work for studying and constructing the physical maps. Chromosome V from strain A364a was isolated 'by pulsed-field gradient gel eleotrophoresis (PFGE). Gel slices containing chromosome V DNA were digested with two rare cutting enzymes, NotI and SfiI, and three 6-Nt recognizing enzymes, Smal, Sstll and ApaI. Several strategies-partial or complete digestions, digestion with different sets of two enzymes, and hybridization with cloned genetically mapped probes (CAN1, URA3, OEN5, PRO3, OHO1, SUP19, RAD5l,RAD3)- were used to align the restriction fragments. There are 9, 9, 15, 17, and 20 sites for NotI, SfiI, SmIl, SstII and ApaI respectively in the map of the A364a chromosome V. Its total length was calculated to be 620 Kb (Kilo-bases) .The distributions of the cutting sites for these five enzymes through the whole chromosome are not uniform. A comparison between the physical map and the genetic map was also made.