Albert Claude

A Fraction from Normal Chick Embryo Similar to the Tumor Producing Fraction of Chicken Tumor I

Summary By means of a method of differential centrifugation at high speed, a fraction can be separated from normal chick embryo tissue, which, in its main characteristics, resembles the active fraction isolated from chicken tumor extracts by the same method. The implications of these observations are discussed.

Proteins, Lipids, and Nucleic Acids in, Cell Structures and Functions

Publisher Summary Several methods are recognized that permit the separation of morphological constituents of the cell, in quantities sufficient for biochemical analysis. This chapter deals with the direct study of nature of a number of cellular complexes and the integration of biochemical functions. The reactivity of chemical compounds is determined not only by their elementary composition, but to a much greater extent, by the spatial disposition of the individual atoms within the molecule, and by the configuration of the molecule as a whole. This property that allows for considerable variations is fully utilized by biological systems and is considered the basis of the specificity of biochemical reactions. Proteins are products and constituents of cells. In the cell, proteins are the parts of the structures of considerable complexity, often in association with phospholipids or nucleic acids. Essentially, proteins and nucleic acids constitute the most popular structural constituents of the cell. However, lipids also account for as much as one-third of the cell mass, and that growing and metabolically active cells have a high phospholipid turnover. Phospholipids and ribonucleic acid are often found together in the cell, being especially concentrated in microsomes, mitochondria, and nucleoli.

A spontaneous, transplantable renal carcinoma of the mouse: Electron microscope study of the cells and of an associated virus-like particle

The present report constitutes an electron microscope survey of the morphology of the cells of a spontaneous, transplantable carcinoma of the kidney, developed and grown in the BALB/c strain of mice. Two main features appear to be of particular interest: (1) dense nuclear inclusions; and (2) virus-like particles found in constant association with the cytoplasm of the renal tumor cells.

“Spreading” Properties and Mucolytic Activity of Leech Extracts

Summary and Conclusions 1. Leech extracts contain a powerful mucolytic enzyme, as shown by its effect on the viscosity of chicken tumor I extracts. 2. Leech head extracts exhibit a mucolytic activity considerably greater than that of similar extracts obtained from the rest of the leech body. A comparable quantitative relationship is found to exist between head and body extracts when tested for another property, e. g., their power to spread in the rabbit skin. 3. The parallelism in the strength of various extracts, as regards both mucolytic activity and spreading power, supports the view that the “mucinase” and the leech spreading factor may be identical. 4. A mucoprotein has been prepared from normal rabbit skin. 5. The viscosity of a skin mucoprotein solution is rapidly and considerably reduced by the action of leech extracts. 6. The effect of leech extracts on the skin mucoprotein in vitro suggests that their ability to spread through the skin may be due, at least in part, to their power to cause hydrolysis or depolymerisation of the same or a similar compound in vivo.

Cell morphology and the organization of enzymatic systems in cytoplasm.

The past development of biological sciences demonstrates that any significant advance, is the result of technical progress, or follows the application of new methods borrowed from other fields. One may wonder what credit would have remained attached to the wise writings of Claude Bernard if he had not been guided, in some of his inquiries, by a tool as simple as the reaction between iodine and glycogen. A slight improvement in the resolving power of microscopic lenses, brought about around the year 1827 by Amici, who succeeded in correcting the optical aberrations of the early microscopes, terminated a deadlock that had lasted for nearly one hundred and fifty years. Cells were seen, and almost immediately recognized as the basic units of living matter. In the next hundred and ten years or so, exploration of the interior of the cell itself was mostly confined to microscopical observation. All the morphological elements of the cell that could be seen by means of the microscope were discovered and, for good measure, some artifacts such as the Golgi apparatus. As regards the organization of the cell and the chemical constitution of its parts, the information gathered derived mostly from indirect observations, and the meaning of tests performed under the microscope remained generally doubtful. For this reason our knowledge of the cell constitution has been until recently, and to a large extent, a morphological concept.

Mitochondrial Cristae during Liver Regeneration

Elongated, dumbbell-shaped mitochondria, containing longitudinal stacks of lamellae, have been described in the liver of rats subjected to certain toxic agents, such as ammonium carbonaie or dinitrophenol; their occurrence and particular morphology have been considered to be the expression of degenerative processes, and the intramitochondrial lamellae likened to myelin figures [1, 2]. Dumbbell-shaped or elongated forms of mitochondria, with apparently concentric longitudinal cristae have been observed in rats following administration of thyroxine in excess [3]. Lehninger has pointed out that the latter extended or dumbbell-shaped configurations may be related to mitochondrial growth and division [4].

Further Experiments on the Effect of Testicle Extract on the Agent of Chicken Tumor I

Conclusion In agreement with the results of Hoffman, Parker, and Walker, Chicken Tumor I agent is spread when injected together with testicle extract and the resultant lesions are markedly enhanced.