Elektronenmikroskopische Untersuchungen zur Degeneration der Dunenfedermelanozyten

Zusammenfassung Die Degeration der Eumelanozyten in den Erstlingsdunen der Wachtel(Coturnix coturnix) ist licht- und elektronenmikroskopisch vom Ende der Pigmentierung bis zum vollständigen Abbau untersucht worden.Nach der Phagozytose der Pigmentzellausläufer durch die Primärleistenzellen runden sich die Perikaryen der Melanozyten ab. Dabei werden sie vom Pulpaepithel zwar vollständig umschlossen, jedoch nicht zellulär aufgenommen. Ihr Zytoplasma wird in der Folgezeit so stark kondensiert, daß mit Ausnahme unreifer oder reifer Granula sämtliche Zellorganellen verschwinden und ein homogen dicht erscheinendes Material mit unregelmäßiger Form zurückbleibt. Am Ende dieser Entwicklung sind von den über lange Zeit durch Desmosomen und tight junctions miteinander verbundenen Zellmembranen der Pulpaepithel- und Pigmentzellen nur noch Bruchstücke erhalten.

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Electron microscopic investigation of the melanocyte degeneration in down feathers

Summary The degeneration of eumelanocytes in down feathers of the quail(Coturnix coturnix) embryo has been investigated from the end of pigmentation to the total degradation with the aid of light and electron microscopy.Following phagocytosis of the pigment cell processes, the cell bodies of the melanocytes become round. Thereby they become completely surrounded by the cylinder cells but are nonetheless not taken up by these cells. The melanocyte cytoplasm subsequently becomes markedly condensed so that with the exception of mature and immature melanosomes, all cell organelles disappear and a homogeneously dense material or irregular form remains. At the end of this development, there exist only fragments of the cylinder and pigment cell membranes that had been previously held together for a long period by desmosomes and tight junctions.

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Folgende Abkürzungen werden verwendet Bl Basallamina - FS Federscheide - Fz Fibrozyt - K Kern - M Mitochondrium - Mz Melanozyt - PD Periderm - PE Pulpaepithel - Pl Plasmalemm - RD Radius - RDP Radiogenplatte - RM Ramus Mark - RMS Ramogensäule - RP Randplatte - RR Ramus Rinde     

Another name for the Umbrella Bamboo

The new combinationThamnocalamus spathaceus is made.     

Photosynthetic preparation and characterization of 13C-labeled carbohydrates in agmenellum quadruplicatum

The blue-green alga Agmenellum quadruplicatum (strain PR6) has been used to prepare photobiosynthetically ¹³C-labeled d-glucose, 2-O-(α-d-glucopyranosyl)-glyceric acid (glucosylglycerate), 2-hydroxy-1-(hydroxymethyl)ethyl α-d-gluco-pyranoside (glucosylglycerol), and α-d-glueopyranosyl β-d-fructofuranoside (sucrose). When grown to a cell density of 4.4 g.L^-1 (dry weight) under nitrate-nitrogen limiting growth conditions for 120 h, the algal cells contained 38% of the dry-cell weight as(1 → 4)-α-d-glucan (amylose). About 1% of the dry-cell weight was glucosylglycerol, glucosylglycerate, and sucrose. Glutamate was obtained, together with carbohydrates of low molecular weight, when the cells were extracted with chloroform-methanol; d-glucose was recovered from the extracted cells by acid hydrolysis of the starch. The algae were grown by using 20 mol% [¹³C] carbon dioxide for preparation of labeled carbohydrates and for cellular component identification by whole-cell n.m.r. spectroscopy.     

Prehistoric cultivated cucurbits from the Viru Valley,Peru

A sample of 535 specimens of cucurbits were retrieved from archaeological deposits in the Viru Valley, Peru, from contexts dated between ca. 1800 B.C.– 1100 A.D. by Carbon-14 analysis and cultural associations. Cultivars ofCucurbita maxima Duch. and C.moschata (Duch.) Duch. ex Poir. are found to be restricted, respectively, to early and late chronological periods, with no overlap. Cultural and ecological factors are suggested to account for the observed temporal and spatial variations in species occurrence. Comparison of materials from other coastal valleys indicat es significant, but presently unexplainable, spatial and temporal differences in the distribution of these species. Supportive evidence for South America as an independent center of domestication for C.maxima tis offered.     

Relationships between cell-substratum interactions and the distribution of concanavalin A receptors of mouse embryo fibroblasts

The mobility of concanavalin A (ConA) receptors on the surfaces of mouse embryo cells are affected by cell-substratum interactions. When the cells are grown on a substratum from which they are easily detached by EDTA, their receptors have an increased mobility and are redistributed into patches after incubation with ConA at 37 °C.     

Turnover of endogenous, microinjected, and sequestered protein in Xenopus oocytes

Pulse-labeled oocyte proteins were found to have a maximum average half-life of 73 h. In general, larger peptides underwent degradation at a faster rate than smaller peptides. In this respect, oocytes are similar to most other cells. Microinjected ¹²⁵I-labeled bovine serum albumin (BSA) was degraded over a 40 h period with a half-life of 20–30 h, regardless of the method of protein labeling, culture medium employed, size of oocyte microinjected, or hormonal history of the oocyte. The last two results, if applicable to oocyte proteins in general, imply that protein catabolism is constant throughout the later stages of oogenesis and that growth is primarily regulated by a stimulation of anabolism. Individual proteins microinjected into oocytes undergo rates of degradation consistent with turnover rates obtained in other systems. Sequestered ¹²⁵I-labeled BSA is only partially (40%) degraded, which indicates that, unlike microinjected ¹²⁵I-labeled BSA, it has access to a cytoplasmic compartment (yolk platelets?) within which it is relatively stable.     

Anthropology and mental health: Reflections on interdisciplinary growth

The publication of Joseph Westermeyer, ed., Anthropology and Mental Health: Setting a New Course, is the departure point for taking stock of past and present links between anthropology and psychiatry. These reflections relate historical trends to the conference volume which contains examples of recent interdisciplinary research. The article critically reviews some of these and then suggests other recent or current work, not mentioned, which the author considers representative of some of the promising results of anthropological contributions to psychiatric interests. Questions are raised, but left unanswered, which might be further examined in attempts to continue long established interdisciplinary collaboration.