19-hydroxycoronaridin und 19-hydroxyibogamin,zwei antibiotisch wirksame alkaloide vom ibogamin-typ

During the separation of an extract from Tabernaemontana glandulosa, small amounts of a new alkaloid were obtained for which the structure 19-hydroxycoronaridine was deduced. This new alkaloid and 19-hydroxyibogamine, which can be obtained from it, show marked antibiotic activity in the agar plate diffusion test.     

Retinal projections in European Salamandridae

Summary The retinal projections to the brain were studied in three species of European Salamandridae using anterograde transport of horseradish peroxidase and autoradiography. The results obtained were basically identical for all species and confirmed earlier findings on the fiber supply to the preoptic nucleus and the basal optic neuropil. In the anterior thalamus projections to three distinct terminal fields are clearly visible: (i) the diffusely stained corpus geniculatum thalamicum, (ii) the neuropil of Bellonci, pars lateralis, and (iii) a dorsomedial terminal field, the neuropil of Bellonci, pars medialis. Caudal to these terminal fields is an almost terminal-free region, the lateral neuropil. In the posterior thalamus a medial terminal field, the uncinate field, and a laterally located terminal field, the posterior thalamic neuropil, are distinguishable. The tectum opticum displays as many as four dense layers of retinofugal fibers and terminals in the rostral part and, in addition, a more densely stained strip of neuropil running from rostral to caudal over the tectum. The extent of ipsilateral fibers is greater than previously reported in other urodele species. They supply the medial and the lateral parts of the neuropil of Bellonci, the uncinate field, and reach the tectum opticum via the medial optic tract. Further, they form terminals in the innermost optic fiber layer throughout the rostral half of the ipsilateral tectum. A small proportion of ipsilateral fibers contributes very sparsely to all other thalamic terminal fields, leaving only the caudal part of the tectum and several layers of the rostral tectum completely free of a direct retinofugal fiber supply.     

The lateral photoreceptor of the barnacle,Balanus eburneus

Summary The lateral eye of the barnacle, Balanus eburneus, fixed in highly concentrated osmium is a lens-shaped body of approximately 250 m in diameter and about 75 m thick. It contains three photoreceptor cells which occupy about 42% of its volume. The photoreceptor cells are irregularly shaped and extend countless dendritic processes which bear rhabdomeres at their ends. Individual rhabdomeres come into contact with rhabdomeres originating from dendrites of the same or of one of the other visual cells. Thirteen per cent of the volume of the photoreceptor cells is taken up by the rhabdomeres. The membranes of the rhabdomeric microvilli contain globular subunits which suggest a 70 Å spacing of rhodopsin molecules. There are two kinds of glial cells. One kind, type A glial cells, makes contact with the fibrous capsule of the photoreceptor. The other kind, type B glial cells, is associated with the photoreceptor cells and extends countless tiny cytoplasmic extensions which interdigitate with similar extensions of the receptor cells. There are approximately 95 type B glial cells and 130 type A glial cells in the receptor. The cytoplasm of the photoreceptor cells contains countless small Golgi fields, mitochondria, microtubules, multivesicular and multilamellar bodies. The extracellular space of the photoreceptor is less than 0.1% of its total volume.The authors wish to thank Mrs. G. Theisen and Miss D. Hupp for expert technical assistance and Drs. M. Behrens, C. Helrich, and C.C. Krischer for many inspiring discussions. This study was partly supported by the SFB 160 of the Deutsche Forschungsgemeinschaft     

Underreplication of satellite DNAs in polyploid ovarian tissue of Drosophila virilis

The satellite DNAs of Drosophila virilis have been examined in diploid and polyploid tissues by isopycnic ultracentrifugation and thermal denaturation experiments. Previous work has established that the satellite DNAs are under replicated in the polytene chromosomes of the salivary glands of D. virilis. The results of the present experiments demonstrate that this underreplication also takes place in the ovaries which contain nurse cells and follicle cells. These tissues are polyploid but do not show polytene chromosomes.     

Expermental contribution on the genesis of arteriosclerosis caused by hypertension]

Autoradiographic tests carried out on rats with renal hypertension using 3H-proline resulted in an acclerated collagen synthesis by media cells of aorta and coronary arteries. Electronmicroscopically an increased content of collagen fibers and an enrichment of ruthenium-red-positive substances in the extracellular space were found. The 35S-sulfate-incorporation in aorta and coronary arteries of animals with hypertension is also increased. These changes in the extracellular space of the vascular wall have an atherosclerosis promoting effect, probably caused by a distrubance of the permeability.