The immunohistochemical localization of the glycosphingolipid asialo-GM1 in the intestine of weaned piglets.

The duodenum, jejunum, ileum, cecum and colon of three male hybrid piglets, 4 weeks old just after weaning, were investigated for the immunohistochemical localization of the asialoganglioside, GM1 (asialo-GM1). The study revealed various degrees of labelling for this acid glycosphingolipid in neural, epithelial and blood elements in all the gut segments. The immunolabelled neural structures, represented by ganglionic perikarya and nerve fibers, were distributed throughout the intestinal wall and showed quantitative variations in the various regions. In contrast the numerical evaluation of labelled epithelial cells was encountered only in the terminal jejunum and along the entire ileum, cecum and large intestine. In addition, a heterogeneous population of immunolabelled leukocytes was spread randomly in the lamina propria and submucosa of the entire intestine and did not show any apparent quantitative fluctuations between the different parts. The observations regarding the typical distribution patterns of the asialoganglioside GM1 in ganglionic perikarya and epithelial cells of weaned piglets are discussed in relation to their possible functional significance in the intestine and other mammalian organs.

The immunohistochemical localization of synaptophysin protein (p38) in the gastro-entero-pancreatic (GEP) system of reptiles.

The gastro-entero-pancreatic (GEP) system of four reptilian species: turtle (Emys orbicularis), lizards (Lacerta viridis and Lacerta agilis) and snake (Natrix natrix) has been investigated immunohistochemically for the presence and topographic distribution of synaptophysin. Among the studied reptiles, only in turtles were neural, glial and neuroendocrine elements labelled for this marker protein. Semi-quantitative evaluation of the immunolabelled neural structures distributed throughout the gastroenteric wall revealed, with two exceptions, highly significant mean differences between the successive gut segments. Significant mean differences were noted also between myenteric and submucosal neurons immunolabelled in the various gastroenteric regions. Moreover, the comparison of ganglionic perikarya groups showed, at least in the stomach, significant mean differences. The amounts of immunopositive glial cells seemed to vary similarly to those of nerve fibers along the entire gastrointestinal tract. Finally, every "closed" and "open" population of immunopositive epithelial cells showed typical fluctuations along the gut. In addition to the distribution of synaptophysin in the GEP system of turtles, the above findings furnish evidence that this marker protein, which is widespread in mammals, is only occasionally expressed in reptiles and probably in most poikilothermic vertebrates.

Serotonin (5-hydroxytryptamine, 5-HT) immunoreactive endocrine and neural elements in the chromaffin enteropancreatic system of amphibians and reptiles.

The diffuse chromaffin enteropancreatic system of nine species of amphibians (newts, frogs) and reptiles (turtles, lizards, snakes) was investigated immunohistochemically for the presence and topographic distribution of serotonin (5-hydroxytryptamine, 5-HT). The study revealed various numbers of serotonin-producing cells in the pancreas and intestinal epithelium and also immunolabelled nerve profiles in the villi of all species studied. In addition, two different morphological populations of serotonin cells ("open" and "closed") were localized in the functional segments of the intestines in the representative species of all the taxa investigated. Semi-quantitative evaluation of the immunolabelled pancreatic and enteric cells revealed significantly different mean numbers of labelled cells in different amphibian and reptilian taxa, and also between the various successive gut segments of each taxon. The ratio between "open" and "closed" varieties of serotonin cells recorded along the intestines followed a decreasing trend, progressive in lizards and snakes and more abrupt in newts, frogs and turtles. The above findings may help resolve several key stages of the phylogenetic evolution of poikilothermic vertebrates.

On the evolution of erythrocyte programmed cell death: apoptosis of Rana esculenta nucleated red blood cells involves cysteine proteinase activation and mitochondrion permeabilization.

Batracian Rana esculenta erythrocytes cell death induced by either calcium influx, or staurosporine, involves typical apoptotic phenotype. Our data reveal: (i) a drastic modification of the cell morphology with loss of the ellipsoidal form as assessed by phase contrast microscopy and scanning electron microscopy; (ii) an exposure of the phosphatidylserine residues in the outer leaflet of the cell membrane; (iii) a caspase-3-like activity; (iv) a mitochondrial membrane potential (Delta Psi m) loss; and (v) a chromatin condensation and fragmentation. Erythrocyte chromatin condensation and fragmentation are prevented by caspase and calpain peptide inhibitors. These inhibitors also prevent Delta Psi m loss supporting the idea that mitochondria is a central sensor for Rana erythrocytes cell death. Our observations highlight the conservation of the programmed cell death machinery in erythrocytes across kingdom.