Abstract: To obtain a selective marker suitable for screening of thermophilic bacteria such as Thermus thermophilus. T. thermophilus are good research materials for investigating the interrelation between enzyme structures and functions since they are stable at extreme pH, crystallize easily and are easy-to-handle.

Abstract: It is desirable to have selective markers suitable for screening of thermophilic bacteria such as Thermus thermophilus. T. thermophilus are good research materials for investigating the interrelation between enzyme structures and functions since they are stable at extreme pH, crystallize easily and are easy-to-handle. Novel mutants of Staphylococcus aureus kanamydn nucleotidyltransferase with markedly improved thermostability are disclosed, as well as a selective marker using the same, and a screening method for thermophilic bacteria such as T. thermophilus using said selective marker.

Abstract: The cleaning method for use in an electrophotographic copying apparatus of the type removing toner images remaining on the surface of a photoconductor by a cleaning blade which includes the steps of bringing the cleaning blade into pressure contact with the photoconductor at least prior to the movement of the photoconductor, and moving the cleaning blade away from the surface of the photoconductor after the movement of the photoconductor is stopped with completion of copying process.

Abstract: An imaging optical system (34) scans an original document (58) and radiates a light image thereof onto a photoconductive drum (31) to form an electrostatic image which is developed to form a toner image. A first pulse generator (62) is driven synchronizingly by rotation of the drum (31) to produce first pulses. A second pulse generator which may include a clock pulse generator (19) for a microcomputer (12) used to control the operation of the copying machine (11) and a frequency divider (78) produces second pulses having a frequency typically ten times that of the first pulses. First and second counters (71), (79) count the first and second pulses respectively, the second counter (79) being reset by each of the first pulses. A sensor (83) senses a predetermined scan position of the optical system (34) and generates an electrical signal.