AUTOPHAGY AND ACID-PHOSPHATASE-ACTIVITY IN THE CORPORA ALLATA OF ADULT MATED FEMALES OF DIPLOPTERA-PUNCTATA

The corpora allata exhibit cycles of synchronous cell growth and atrop hy during ovarian cycles in adult females of the cockroach Diploptera punctata. In the present report, the process of synchronous autophagy of organelles which results in cellular atrophy was investigated. In g eneral, unwanted organelles were sequentially sequestered by several d ifferent mechanisms and then targeted for destruction. Autophagy was i nitiated on day 4 when corpus allatum cells were largest and most acti vely synthesizing juvenile hormone. The first sign of the initiation o f autophagy was aggregation of ribosomes in an isolation membrane. By day 5, many organelles were isolated in the autophagic vacuoles. The r ibosome-containing vacuoles were wrapped by flattened stacks of Golgi cisternae to form conspicuous whorl-like autophagosomes. This is a pre viously undescribed type of autophagic vacuole with the entire complex of Golgi cisternae forming part of the autophagic membranes. Smooth e ndoplasmic reticulum was wrapped into membranous autophagic vacuoles w ith concentric arrays of double membranes. Plasma membrane was invagin ated and then isolated in a multivesicular body. These three different types of isolated vacuoles did not show acid phosphatase activity as indicated by histochemical staining with beta-glycerophosphate as subs trate. Subsequently, these autophagosomes fused with each other and wi th 1 degrees or 2 degrees lysosomes to form giant autophagolysosomes. Some mitochondria appeared to have coalesced directly into autophagoly sosomes. Golgi complexes were evident during this period; they activel y participated in making lysosomal enzymes. Cytoskeletons were frequen tly observed in the vicinity of autophagic vacuoles and were presumabl y involved in the transport of the vacuoles. As a result of lysosomal degradation lipofuscins and dense bodies were frequently observed by d ays 9-12 indicating atrophy of corpus allatum cells. Structural parame ters, especially those present early in autophagy, such as the isolati on membrane, ribosome-containing vacuoles and whorl-like autophagosome s, can be used to search for potential growth regulators responsible f or the induction of autophagy, of the corpora allata, and the subseque nt termination in juvenile hormone synthesis.