Electron microscope examination of two plaque variants from a nuclear polyhedrosis virus of the alfalfa looper, Autographa californica

This investigation looks into the ultrastructural differences between plaque variants of the alfalfa looper nuclear polyhedrosis virus. The variants exhibit distinct differences in polyhedra morphology and enveloping of the nucleocapsids.Tissues from larvae infected per os or subcutaneously with virus from one type of plaque always contained virus representative of both plaques. This was not true of the in vitro cultured cells. In those cells, a culture infected with one plaque type always developed infections that were typical of that particular plaque.     

Enumeration of denitrifying microbial populations in turf

Summary Denitrifer populations of a silt and silt loam soil under a Kentucky bluegrass turf were enumerated using the most probable number (MPN) procedure. The influence of soil texture, soil depth, soil moisture, and additions of nitrate fertilizer on denitrifier populations were determined. Saturated soil conditions increased denitrifier populations 87-fold in the silt soil and 121-fold in the silt loam soil. Denitrifier populations did not differ significantly between soil depths and additions of fertilizer nitrate did not influence populations.