Cell Biology International Reports, Vol. 14, Abstracts Supplement 1990 215

P545 EFFECTS OF NH4Cl ON THE PROCESSING OF PHOSPHORYLATED CATHEPSIN D

Ciro Isidoro, Gabriella Bonelli, *Andre,j Hasilik and Francesco M. Baccino. Univer- sities of Torino (1) and *Muenster (RFGI.

The mannose 6-phosphate (M6P) receptor mediated transport of lysosomal enzymes depends on the presence of phosphomanno- SYl groups in the oligosaccharide side chains of the proenzyme and on the inter- action of these groups with specific receptors. We analyzed several normal and tumor cells of murine and human origin for their efficiency in generating the M6P groups on cathepsin D (CD). We show here that there is a correlation between

the Proportion of phosphomonoester (PMEI groups present on the enzyme and its se- gregation. Transformed cells secrete a higher fraction of the newly synthesized proCD than normal cells. NHdCl, which is known to disrupt the receptor mediated segregation of lysosomal enzymes by impairing the reutilization of receptors,

enhances the secretion of CD much stron- ger in the normal than in the transformed cells. The decrease in the proportion of PME groups in the presence of NHsCl indi- cates that in the examined cells, like in the previously studied U937 ceils, this agent impairs the processing or transport of proCD in the Golgi apparatus.

P547 3DRRCONSTRUCTIONOFSERL4LSECTIONSOF BLO~DP~ATEL~ BYAPERSONALCOMFUTER

Rolf Dierichs, Christian Sttimpel. Institute of Anatomy, Uni- versity of Mlinster, D-4400 Master, Fed. Rep. Germany.

To investigate the complex shape change occuning during platelet activation, platelets where fixed by impact freezing and freeze-substitution. Serial sections wa digitized and submit- ted to 3D reconstruction. The hardware consists of a Macintosh II (Apple computer).

CPU: 68020 processor (Motorola), 68881 arithmetic coproces- sor, 256 colors graphic caid, High Resolution Color Monitor, graphic Tablet (MacTahlet, Summagraphics). The program allows arrangements of the two-dimensional in-

puts by shifting and rotation. Corn~tions and additions or re- movals are possible at any time. After completing the st?rial in- puts, a list of camera parameters including three spatial rotation axes can be freely chosen for each of the reconstruction aspects desired. This can be done by interactive display using a wire frame model. By triangulation, the reconstructed models may be represented as stacks of slices, or the surface of each indi- vidual object may be continuously modelled. If&sired, trans- parency may be attributed to some details of the models in or- der to reconstruct envelopes and contents in the same model. The various aspects of reconstructions ate collected in a film sequence. The reconstructed models give insights into the stmcture of

internal membranes (the “open canalicular system”) and their contact to the cell surface, the position and shape of secretory granules, their rearrangements during the processes of shape change and secretion. The shape of activated platelets and the integration of internal membranes into the platelet surface can be shown to cormspond to the ability of platelets to form con- taets to other platelets and to bind surface ligands: cationized ferritin. that causes phUelet activation by itself, and fibrinogen, that binds to the gIycoprotein IIb-m-complex and influences the platelet responses to the activation by thrombin.

P546 DISTRIIBUTION of SME HYDROLITIC ENZWIES IW THE DIGESTIVE SLMi OF HELIX arw

t David Parcel,* Antonio bleeodros, + Juan Ii. Sueno, + Francisco Rbadia tlolina. t Servicio de Mcroscopia + Dpto. Eialogia Celular, Universidad de Granada, Spain.

The adenoeera has three types of cel1sri.e. digestive ce115, excretory cells and calciue cell5.

Ye have studied three hldrolitic enzycs: acid phosphatase, alkaline phosphatare and nun-specific erterase ip the adenoeera of the digestive gland of the snail.

The sarples of tissue were taken froe feed snails and starvatlve snails.

The results were: REid Phosphrtase. Light exroscopy: a light colored precipitate was observed in the granules citoplrsre of the digestive cells. Electron eicroscopy: the electron dense probe MS San localiced in the granules and eicrovilli of the digestive cells, in the granules of excretory cells as well as in calciue granules of calciue cell;. w Phosnhatase. The enryre reaction Ha5 elicited both altho light and electron eitrorcopy level in fibroblast. Non-Seecific m. Light ricroscopy: in the cytoplase of the digestive cells a difused reaction, rather than a clueped one, la5 observed. Electron microscopy: a clueped depostion was apparent in the cytoplase and also localized in the granules.

d corparation of the morphological features of the three stated cellular types of the digestive gland in etarvative and feed snails, rendered no apparent diffrence during the observation period. Fig I. RcP Fig 2. RlP Fig 3..Est

P546 MICROCALORIMETRY: A PARAMETER FOR TH CHARACTERISA ION OF CELLS.

Yamamura, M f ., Hayatsu, H ., Miyamae, T2., T 1. Dept. of Biocher. Tokai Univ. School of Med., Boseidai, Isehara, Kanawgawa, 259-11 2. ESCO Ltd., Uusashino, Tokyo,

Heat is produced by living cells but not by dead cells, so the quantity of heat produced should correlate with the state of cells.This study was carried out to test this hypothesis. The heat production of cells under various culture conditions was measured using a therroactive cell analyzer(ESC0 3000).

It was found that (1) the phases of the cell cycle, (2) differentiation and (3) the presence of growth factors altered heat production of cells. These results are expected as the cells were modified by adding stimulating agents such as growth and differentiation factors. The change of heat production in these experiments was directly proportional to the concentration of the stimulating agent. An interesting result is that values in heat production at given culture periods varied although they were expected to remain unchanged. This result is constant and can be interpreted that the parameter of heat production is detecting changes which can not be measured by other methods. Microcalorimetry is thus ultrasentitive method with capacities beyond the scope of established methods. It will be useful for defining the characteristics of cell and other biological constants.