LOW-TEMPERATURE COMPARTMENT FORMATION IN FELINE IMMUNODEFICIENCY VIRUS-INFECTED AND UNINFECTED FELINE KIDNEY-CELLS

This study was to determine if feline immunodeficiency virus (FIV)-inf ected and uninfected Crandall feline kidney (CRFK) cells exhibited a l ow temperature (16 degrees C) block in membrane trafficking between tr ansitional endoplasmic reticulum and Golgi apparatus represented by in termediate compartment formation. Cells were cultured at different tem peratures and membrane changes involving the Golgi apparatus and Golgi apparatus-associated membrane structures were monitored by electron m icroscopy and quantitated. With 30 min of incubation, membranes of the Golgi apparatus stack increased in amount at temperatures of 16 degre es C and below compared to temperatures above 18 degrees C. The increa se was greatest along the major polarity axis as evidenced by an incre ased stack height. Neither the number of cisternae per stack nor the a verage stack diameter (width) was affected by temperature. The respons e was maximal between 15 and 30 min of low temperature treatment of th e cells. Results with cells infected and uninfected with feline immuno deficiency virus were similar. The increase in stack height was due pr imarily to an increase of membranes at the cis face (cis Golgi apparat us network). At 18 degrees C, membranes of the trans Golgi apparatus n etwork accumulated suggesting that import from the cis Golgi network c ould proceed at this temperature, whereas exit from the trans Golgi ne twork was still at least partially blocked. Also increased at 16 degre es C and below were numbers of transition vesicles in the space betwee n the Golgi apparatus and the transitional endoplasmic reticulum assoc iated with the cis Golgi apparatus face. The results suggested interru ption of the orderly nux of membranes into the Golgi apparatus at 16 d egrees C and below. Moreover, the block appeared to be reversible. Upo n transfer from 16 degrees C to 37 degrees C, there was a time-depende nt decrease in the accumulations of cis compartment membrane accompani ed by a corresponding equivalent increase in the membranes of the tran s Golgi apparatus compartment.