beta-Granules were prepared from micro-dissected pancreatic islets of obese-hyperglycaemic mice. This fraction contained 60% of the insulin, 30% of the cytochrome oxidase, 16% of the acid phosphatase activity and 20% of the protein present in whole islets. The isolated granules retained a heavy metal during fractionation. Optimum conditions for granule stability were low ionic strength and pH6, the granules being unexpectedly fragile at pH7.4. The stability of the granules was unaffected by sucrose in the concentration range 50-320mm, but 1% (w/v) sodium deoxycholate released all insulin. A solubilizing effect was also noted with ATP and citrate. Spinning through 1.6m-sucrose yielded a further purification in relation to mitochondria and acid-phosphatase-carrying particles but virtually no purification in relation to protein. Electron microscopy revealed that the major contaminants were rough-surfaced vesicles and membranes. A separation of granules from acid phosphatase was achieved by phase distribution in polyethylene glycol and dextran. The location of the enzyme to the interphase was so pronounced in systems buffered with lithium phosphate that the technique may be used for future purification of acid-phosphatase-carrying particles from the beta-cells.
An ultrastructural modification of the sulfide‐silver method disclosed that rat and cattle eosinophilic granulocytes contain heavy metals in the non‐crystalloid parts of their specific granules and possibly also in the cell membrane. Metal analysis of isolated granules by means of atomic absorption spectrophotometry indicated that the principal metal contained in the granules is zinc. Consequently the metal demonstrated ultrastructurally in eosinophil granules is thought to be zinc.
Summary. Treatment of vertebrate pancreatic islet tissue with hydrogen sulphide, thus initiating the sulphidesilver procedure for ultrastructural visualization of heavy metals in tissues, evoked marked swelling in zinc-containing secretion granules of fl-cells in several species rapidly leading to disruption of many granules. Other organelles of the fi-cells were unaffected, as also were the secretion gramfles of adjacent zinc-containing ~2-cells. Likewise, fiand ~2-granules with no heavy metals or only traces of them, like those of the guinea pig and the coypu, were all well preserved after gassing with hydrogen sulphide. It is suggested that this observation may give some information on insulin-zinc-sulphydryl relationships in vivo.
Labilitg structurale des granules de sdcrgtion contenant du zinc des cellules fl du pancrgas aprgs gazage avec de l'hydrog~ne sulfurdRdsumd. Le traitement des ilots pancr6atiques de plusieurs espgces de vert6br6s avec de l'hydrog~ne sulfur6, eonstituant ainsi la phase initiale de la mgthode sulfureargent pour la visualisation ultrastructurale des m6taux lourds darts les tissus, provoquait un gonflement marqu6 des granules de s6crgtion zineif~res des cellules fl dans plusieurs esp~ees, conduisanb rapidement ~ la rupture de beaueoup de granules. D'autres organelles des cellules fl restaient intacts, ainsi que les granules de s6cr6tion des cellules e2 zincif~res voisines. De m6me, les granules fl et ~ sans ou avec seulement des traces de m6taux lourds, eomme ceux du cobaye et du nutria, 6taient bien conserv6s apr~s le gazage avec l'hydrog6ne sulfur6. --On sugg~re que cette observation peut donner quelques aspects sur les relations insuline-zinc-sulfhydryl in vivo.
Strulcturelle Labilitgit yon Selcretionsgranula mit Zinlcgehalt in panl~reatischen B-Zellen naeh Begasung mit SehwefelwasserstoffZusammenfassung. Behandlung mehrerer Arten von pankreatischem Inselgewebe yon Wirbeltieren mit Sehwefelwasserstoff, womit die Sulfid-Silber-Methode zur ultrastrukturellen Darstellung yon Gewebe-Schwermetallen eingeleitet wird, verursacht eine ausgesprochene Anschwellung der zinkhaltigen Sekretionsgranula der flZellen, die schnell zum ZerfM1 der Granula fiihrt. Andere Zellorganellen der fl-Zellen waren nicht besch~digt, auch nicht die Sekretionsgranula der benachbarten ~-Zellen. Ebenfalls waren fl-und ~-Granula mit keinen oder nur Spuren yon Schwermetallen, wie die des Meerschweinchens und der Nutria, alle wohlbehalten nach der Behandlung mit Sehwefelwasserstoff. --Als eine Arbeitshypothese fiir zukiinftige Untersuchungen wird angedeutet, dal3 diese Beobachtung yon Bedeutung in Bezug auf die InsulinZink-Sulfhydryl-Verh~ltnisse sein kann.
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