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M L Beauchemin

Publications and source records attributed to M L Beauchemin.

9 recordsLinked to original sources
PubMed1977

Effects of colchicine on phagosome-lysosome interaction in retinal pigment epithelium. I. In vivo observations in albino rats.

The retinal pigment epithelium (RPE) from young albino rats was examined under light and electron microscope 2 1/2 to 16 h after intravenous injections of colchicine (0.5 mg per 100 gm body weight). One of the primary effects of colchicine treatment on the RPE is the appearance of extensive acPase-positive dense body aggregates in the Golgi area. The size of the aggregates and the disappearance of microtubules appear to be related to the length of time allowed for colchicine to react. Acid phosphatase (acPase) activity is localized on the dense body aggregates and is particularly evident at a light microscopic level, where it can be observed as darkly stained clumps. Dense bodies are only rarely seen in the immediate proximity of acPase-positive phagosomes in colchicine-treated animals. The results of these experiments suggest the existence of an intracellular transport mechanism for acPase-carrying dense bodies. This intracellular transport is inhibited by colchicine, being probably related to a block of microtubular assembly.

Animals↗
PubMed1975

Retinal capillary basement membrane thickness in spiny mice (Acomys cahirinus) with induced and spontaneous diabetes.

Basement membrane thickness was measured in two groups of spiny mice (Acomys cahirinus): one with spontaneous diabetes, the other with streptozotocin-induced diabetes. A statistical analysis of the morphometric results of the two groups showed a significant basement membrane thickening in the group with induced diabetes when compared to the spontaneously diabetic group.

Animals↗
PubMed1975

'Immobile' (im), a recessive lethal mutation of Xenopus laevis tadpoles.

'Immobile' (im) is a recessive lethal mutation discovered in the F3 of a Xenopus (Xenopus laevis laevis) originating from a mesodermal nucleus of a neurula transplanted into an enucleated egg. The im embryos do not contract after mechanical stimulation nor do they present any spontaneous contraction from the neurula stage onwards. Development proceeds normally during the first days after which deformation of the lower jaw and tail are observed. The im tadpoles die when normal controls are at the feeding stage. Nevous and muscular tissues are histologically normal in the mutant tadpoles; at advanced stages, however, an irregularity in the path of the myofibrils is observed which is especially conspicuous in the electron microscope. Cholinesterases and ATPase are present in the mutant muscles. Parabiosis and chimerae experiments have shown that parabionts and grafts behave according to their own genotype. Cultures of presumptive axial systems with or without ectoderm lead to the conclusion that, first of all, the abnormality is situated in the mesodermal cells and secondly that the first muscular contractions in normal Xenopus laevis are of myogenic origin. The banding pattern of the myofibrils is normal as was shown by obtaining contractions of glycerol extracted in myoblasts with ATP. It seems therefore that in this mutation, the abnormality is situated in the membraneous system of the muscular cell, sarcoplasmic reticulum and/or tubular system as is probably the case in the mdg mutation of the mouse.

Adenosine Triphosphatases↗