Arthropodisierung ais biomechanischer Prozeß und die Entstehung der Trilobiten-Konstruktion

The conditions are pointed out under which the body construction of annelids could have been transformed into that of arthropods. As an adaptation to a vagile life near or in the bottom and to an uptaking of food by filtering of particles the parapodia of annelid-like organisms were shifted into a more ventral position. This process required certain bracings by connective tissue and muscles in the body, controlling the body shape. Immobilisation of body parts, initially in the dorsal region, allowed stiff skeletal structures to arise. The sclerotisation caused an increase of efficiency of the motoric system, since the body form was reliably controlled no more by the action of muscles, as in the hydrostatic skeleton systems of worms, but by rigid skeletal plates, to which muscles can be inserted. The result of this transformation were broad and flat arthropod-constructions with ventral food groove, through which the row of endites of the limbs transported a stream of food along the median line to the mouth. On this constructional level the trilobites are the first group with many species. Their structures can be explained as a result of the constructional preconditions of their ancestors and of the adaptations during the transformation, leading from annelid-like hydrostatic skeleton systems to typical arthropods with an exoskeleton-muscle apparatus.     

Stereo high voltage electron microscopy of melanophores : Matrix transformations during pigment movements and the effects of cold and colchicine

Pigment migration in isolated melanophores of the angelfish, Pterophyllum scalare, has been studied by high voltage electron microscopy. Cells were isolated from the scales by collagenase and allowed to spread on Formvar and carbon-coated gold grids. Melanophores were then fixed by glutaraldehyde and osmium tetroxide and critical-point dried for viewing of whole cells in a high voltage electron microscope (1000 kV). The three-dimensional organization of the cytoplasmic matrix was stereoscopically examined in different states of pigment distribution, as well as under cold and colchicine treatment. The most prominent matrix constituent is an extensive mesh of cytoplasmic filaments (microtrabeculae) 2–18 nm in diameter that make contact to microtubules, pigment granules, and mitochondria. Microtrabeculae undergo dramatic changes in structural appearance in association with different phases of pigment movements. Cells fixed in the process of pigment aggregation are characterized by thickened and beaded trabeculae which may form irregular clots. Part of this material trails behind centripetally moving melanosomes. In dispersing cells, microtrabeculae are straight and of relatively uniform thickness throughout their length and form a highly ordered three-dimensional lattice. Reconstruction of the mesh in part precedes the arrival of pigment granules.Under the influence of cold or colchicine treatment, microtrabeculae show a high degree of polymorphism, being beaded, branched, or flattened with globose ends. Rather formless heaps are found associated with the surface of pigment granules. Since, however, these treatments also remove microtubules, the other important component of the cytoplasmic frame, alterations in microtrabecular structure may simply be mediated through removal of this organelle. In an attempt to separate the effects on microtrabeculae and microtubules from one another, cells have been cold-treated for only 15 min, a procedure that leaves a considerable portion of microtubules intact. Also under these conditions, microtrabeculae are beaded or transformed to globose heaps and flattened sheets.The observations suggest an involvement of microtrabeculae in the process of granule movement. Centripetal melanosome migration thereby seems associated with a collapse of microtrabeculae which again are reconstructed during pigment dispersion. The cold and colchicine experiments indicate direct effects of these agents on the structure and possibly also the function of the trabecular mesh. The significance and possible chemical composition of microtrabeculae is discussed.     

Electron microscopical-immunocytochemical evidence of ecdysteroids in the prothoracic gland of Galleria mellonella

Summary Fixation of prothoracic glands of Galleria mellonella with a solution containing saponin permits immunocytochemical staining of the entire gland. By this means ecdysteroids were demonstrated electron microscopically to be present in the hyaloplasm and microtubules.Supported by Sächsische Akademie der Wissenschaften zu Leipzig     

E. coli membranes become permeable to ions following T7-virus-infection

Summary Infection of E. coli with the viruses T7 or T3 leads to a dramatic efflux of potassium ions. This ion efflux is caused by the virus particle since no concomitant protein synthesis is required. T7 mutants carrying deletions in the M-gene (Schweiger et al., 1975), however, yield virus particles disturbed in the ion release.     

GD (-) Aachen,a new variant of deficient glucose-6-phosphate dehydrogenase

Summary A deficient G-6PD variant was discovered in 4 males of one family from north-western Germany. Five generations of this family could be studied.The deficient G-6PD was a new variant, called Gd (-) Aachen. Its main characteristics are the following: severe enzyme deficiency in erythrocytes (3% of normal), contrasting with an almost normal activity in leukocytes; normal molecular specific activity (i.e., normal ratio enzyme activity/cross-reacting material); slow mobility in starch gel electrophoresis (92–94% of normal); increased Michaelis constant for glucose-6-phosphate (60–70 M) and NADP⁺ (20–25 M); decreased inhibition constant by NADPH with respect to NADP⁺ (7 M); increased inhibition by ATP; normal utilization of the substrate analogues; slightly biphasic pH curve; thermal instability, and normal activation energy of the enzymatic reaction.The relationships between the hematologic disorders (severe and frequent hemolytic crises) and the unfavorable kinetic modifications are discussed.with the technical assistance of Joelle Marie and Dominique CottreauDedicated to Prof. Dr. H. Schonenberg, Aachen, on his 60th birthday. The first results of this work were presented in part at the Kongress der Deutschen Kinderärzte, München.     

Die Bedeutung der Elytren bei Vertretern desMelolontha-Flugtyps (Coleoptera)

The function of the flapping elytra was investigated in garden shafers (Melolontha melolontha L.) and rhinoceros beetles (Oryctes boas Fabr.).

Ultrastructure of the prothoracic gland cells of the last instar of Galleria mellonella in relation to the state of development

The prothoracic glands of the last instar of Galleria mellonella undergo characteristic alterations of their cellular fine structure closely related to cellular activity. During progressive secretory activity of the gland cells there are extensive plasmalemmal infoldings and formation of a pronounced lacunar system. Mitochondria of the active cell phase are characterized by a specific increase in size and paler colour of the matrix. In contrast to the alterations, nuclei, ER and Golgi cisterns do not undergo any submicroscopic changes during the different phases of cellular activity. The relationship between the substructural phenomena and the specific phases of cellular activity are discussed.     

Gap junction remodeling and altered connexin43 expression in the failing human heart

Gap junctions (GJ) are important determinants of cardiac conduction and the evidence has recently emerged that altered distribution of these junctions and changes in the expression of their constituent connexins (Cx) may lead to abnormal coupling between cardiomyocytes and likely contribute to arrhythmogenesis. However, it is largely unknown whether changes in the expression and distribution of the major cardiac GJ protein, Cx43, is a general feature of diverse chronic myocardial diseases or is confined to some particular pathophysiological settings. In the present study, we therefore set out to investigate qualitatively and quantitatively the distribution and expression of Cx43 in normal human myocardium and in patients with dilated (DCM), ischemic (ICM), and inflammatory cardiomyopathies (MYO). Left ventricular tissue samples were obtained at the time of cardiac transplantation and investigated with immunoconfocal and electron microscopy. As compared with the control group, Cx43 labeling in myocytes bordering regions of healed myocardial infarction (ICM), small areas of replacement fibrosis (DCM) and myocardial inflammation (MYO) was found to be highly disrupted instead of being confined to the intercalated discs. In all groups, myocardium distant from these regions showed an apparently normal Cx43 distribution at the intercalated discs. Quantitative immunoconfocal analyis of Cx43 in the latter myocytes revealed that the Cx43 area per myocyte area or per myocyte volume is significantly decreased by respectively 30 and 55% in DCM, 23 and 48% in ICM, and by 21 and 40% in MYO as compared with normal human myocardium. In conclusion, focal disorganization of GJ distribution and down-regulation of Cx43 are typical features of myocardial remodeling that may play an important role in the development of an arrhythmogenic substrate in human cardiomyopathies.