- n autolysis lysis of plant or animal tissue by an internal process
Century Dictionary and Cyclopedia
- n autolysis Self-dissolution; in physiology, self-digestion; autodigestion. Until recently it was generally held that the only ferments occurring in the animal body were the common ferments of the digestive secretions, and that cellular digestion, in contradistinction to gastro-intestinal digestion, was referable to the peculiar activity of living protoplasm. Salkowski, however, demonstrated as early as 1890 that liver-tissue, when finely minced and kept in saturated chloroform water, will undergo changes which are manifestly analogous to those occurring during pancreatic digestion. For this form of tissue-digestion Salkowski proposed the term autodigestion, and he suggested that probably the process was referable to the action of ferments contained in the liver-cells which were liberated after the death of the latter by the chloroform. Similar changes could be demonstrated in the case of muscle-tissue. Other investigators, while admitting that autodigestion of organs does occur, explained the phenomenon on the basis of a supposed absorption of gastro-intestinal zymogens and their transformation into the corresponding enzyms by the chloroform. This view has been definitely abandoned, it having been satisfactorily demonstrated that Salkowski's interpretation of the process of autodigestion, or autolysis, as it is now more commonly termed, is correct, and that cellular digestion is undoubtedly referable to intracellular ferment-action. This is in accord with observations made in vegetable physiology, where it had already been shown that the transformation of starch in developing seeds, in tubers, and in rhizomes was referable to an intracellular diastase, and that the solution of glucosides and fats was dependent upon the action of enzyms. Nevertheless the full import of intracellular ferment-action was not fully recognized until Büchner showed that even though ferments cannot be extracted from all dead cells by ordinary means, they can be demonstrated after the destruction of the cell-envelop by high pressure, by repeated freezing and thawing, etc. These researches, which were essentially conducted with yeast-cells, and led to the discovery of the intracellular zymose, are now classical. In their general behavior the intracellular autolytic ferments are similar to the common digestive ferments. Here, as there, are proteolytic ferments, diastatic ferments, and lipolytic ferments. There is, however, a greater multiplicity; for in certain cells is recognized the existence also of oxidizing ferments, of ferments which are capable of causing the cleavage of nucleins, of others which can transform amido-acids into amides, and of still others which are capable of splitting off carbon dioxid from certain bodies, etc. Apparently we are only on the threshold of knowledge of these ferments, the number of which in a single cell may be remarkable, as in the liver-cell, where at least 12 different ferments, aide by side, have been demonstrated. Autolytic proteolysis is strictly analogous to peptic and tryptic digestion, but it is noteworthy that the autolytic proteases are more specific in their action. Generally speaking, they cause the cleavage of the albumins of their respective tissues more readily than of heterologous tissues, and certain members of the group, such as the proteolytic ferment of the liver, are totally incapable of acting upon the albumins of other organs, as lung-tissue, for example. Therefore Jacobi has suggested restricting the term autolysis to the destructive action of the ferments of a given organ or tissue upon the corresponding tissue, and designating the action of a given ferment upon a foreign tissue as heterolysis. Whether the autolytic ferments are also capable of constructive action has not yet been ascertained. A priori this appears likely, and it may be imagined that under normal conditions a certain equilibrium of reaction exists between the complex cellular components and the corresponding radicals. The recognition of this principle will lead to a more satisfactory understanding of many problems connected with cell-nutrition, not only under normal but also under pathological conditions. Jacobi has already shown that liver autolysis is much accelerated (in a catabolic direction) in animals poisoned by phosphorus, thus furnishing a satisfactory explanation of many obscure phenomena noted in this condition as well as in allied degenerative changes. The importance of autolytic processes is further exemplified in pneumonia, where the resolution of the exudate is unquestionably largely effected in this manner. There is evidence to show that autclytic processes may be active in the defense of the animal body against bacteria and bacterial products, and hence of moment in the production of immunity. Knowledge of the subject is still in its infancy, but it may safely be asserted that the discovery of autolysis is one of the most important in the domain of physiology and physiological chemistry.