Preparation and discharge of secretion in the subcommissural organ of the rat

Summary The secretion of the subcommissural organ (SCO) of the rat was studied by means of immunocytochemistry at the electron-microscopic level with the use of (1) the polar embedding medium Lowicryl K4M at -30° C, (2) the protein A-gold technique, and (3) a rabbit antiserum against bovine Reissner's fiber (see Sterba et al. 1981).Two different substructures of the ependymal and the hypendymal SCO-cells display a positive immunocytochemical reaction: (1) sacs containing flocculent secretion, which originate from the granular endoplasmic reticulum, and (2) vacuoles filled with fine granular secretion, which are pinched off from the Golgi apparatus. The secretory material of the sacs and the vacuoles is discharged both (i) apically into the cerebrospinal fluid and (ii) basally into intercellular spaces of the SCO-hypendyma. The apically released secretion is condensed to a lamina-like formation, which more caudally assumes the form of Reissner's fiber. The route of the basally released secretion remains, however, vague. The periodically striated bodies, which were thought to be morphological mediators of the discharge of the secretion into the capillaries, are never labeled by gold particles.Supported by grants from the Ministry for Science and Technology of the German Democratic RepublicThe expert technical assistance of Mrs. B. Wolff, Mrs. S. Mehnert, Mrs. E. Siebert, Mrs. Ch. Schneider, and Mrs. I. Seifert is gratefully acknowledged     

Degradation of the radula in the snails Biomphalaria glabrata say and Limnaea stagnalis L. (Gastropoda,Pulmonata)

Summary The radula of snails is formed at the posterior end of the radular gland or pocket, and degraded at the same rate at its anterior end. Degradation is due to different secretory activities of the inferior epithelium of the radular gland. Its secretions seem to degrade enzymatically the matrix of the radular membrane and basal plates of teeth, leaving only chitin containing microfibres and degradation products. The sclerotized parts of the teeth remain unchanged, but as they are now only loosely connected with the radular membrane. they are torn off easily during feeding movements. The rest of the degraded and frayed radular membrane and the subradular membrane are also lost by abrasion during feeding. The cells of the inferior epithelium are connected with each other by septate desmosomes and an elaborate system of deep lateral interdigitation which may provide tensile strength. Extrusion of degraded cells of the inferior epithelium into the subradular membrane takes place, although the thick basal lamina forms a continuous sheath which is closely adjoined to the basal parts of the inferior epithelium. Nerve fibres containing vesicles with electron dense neurosecretory material (deduced from the diameter of 200–250 nm) are attached to this sheath or penetrate into it; they may be involved in the regulation of production and degradation processes during radula replacement. Problems of the forward transport of radula and inferior epithelium are discussed.     

Investigations of the pigments fromCytophaga johnsonae Cy j1

Besides carotenoids a complex of flexirubin-type pigments was isolated from the gliding bacteriumCytophaga johnsonae Cy j1 and separated into 6 components, which partly containe chlorine. In spite of the fact that these components still consist of pigment mixtures, the gross structures of 18 new flexirubin-type pigments could be deduced by spectroscopic and chemical investigations. The results open insights into biosynthesis and structural variety of the flexirubins, the novel non-isoprenoid pigments recently found inFlexibacter elegans.Non-Standard Abbreviations FT Fourier transformation - HPLC high pressure liquid chromatography - M⁺ molecular ion - M/M resolution of mass spectrometer - mu mass units - t _R retention time - TLC thin layer chromatography Part 16: Investigations on metabolites of microorganisms. Part. XV: H. Achenbach, W. Kohl, H. Reichenbach: Die Hauptpigmente vonCytophaga johnsonae. Tetrahedron Lett.1977, 1061. Part XIV: H. Achenbach, J. Witzke: Totalsynthese des Flexirubindimethylethers. Angew. Chem.89, 198 (1977); Angew. Chem. Int. Ed. Engl.16, 191 (1977)     

The isolation of DNA from agarose gels by electrophoretic elution onto malachite green-polyacrylamide columns

Electrophoretic elution of DNA coupled with direct adsorption onto malachite green-polyacrylamide columns was used to isolate double- and single-stranded DNA from agarose gels. Subsequently, DNA was eluted with a high salt buffer and filtered through Sephadex which permitted recovery of the DNA in a low salt buffer at concentrations suitable for heteroduplex analysis by electron microscopy. This method was tested by examining hetero-duplexes formed from the isolated complementary single strands of T7 wild type DNA and a T7 deletion mutant. More than 80% of the reannealed molecules were intact heteroduplexes showing the deletion loop. Irradiation of single-stranded DNA with 254 nm light resulted in distorted, convoluted heteroduplexes while 366 nm light did not show this effect.     

Die Beinmuskulatur und ihre Innervation bei der VogelspinneDugesiella hentzi (Ch.) (Araneae,Aviculariidae)

Zusammenfassung Gestützt auf präparative Untersuchungen und histologische Serienschnitte werden Zahl, Lage, Funktion und nervöse Versorgung aller Muskeln in den Laufbeinen der erwachsenen VogelspinneDugesiella hentzi (Ch.) beschrieben. In den acht Laufbeinen können gleichermaßen jeweils dreißig Muskeln unterschieden werden.Bis auf eine Ausnahme (M. 30) erfolgt die Innervation sämtlicher Beinmuskeln durch den Beinnerv B, wobei die Versorgung durch mehrere (bis zu 6) Nervenäste pro Muskel die Regel ist. Jeder Ast aus Nerv B enthält eine große Anzahl von Axonen. Die aus Ansatz und Ursprung ersichtliche gemeinsame Funktion verschiedener Beinmuskeln spiegelt sich auch in der Innervation aus gemeinsamen Seitenästen von Nerv B wieder.Soweit möglich werden die vermutlich homologen Beinmuskeln aus Untersuchungen anderer Autoren an anderen Arten gegenübergestellt.

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Anatomy of the leg muscles and their innervation in the tarantulaDugesiella hentzi (Ch.) (Araneae, Aviculariidae)

Summary All muscles in the walking legs of the adult tarantulaDugesiella hentzi (Ch.) are described according to their position, function, and innervation pattern. Each leg contains 30 muscles. With the exception of one (M. 30) all of them receive their motor innervation through multiple branches from the main motor nerve B. Muscle 30 is innervated through the mixed nerve A. Each branch leaving nerve B contains a large number of axons.Similarities in the function of different muscles as derived from their attachment at particular leg joints are reflected in the innervation pattern by common branches of nerve B.The leg muscles fromDugesiella are homologized with those of six other species of spiders from different families.

     

Sesquiterpene lactones from Viguiera species

Viguiera eriophora yielded the sesquiterpene lactones erioflorin, acetylerioflorin and 17,18-dehydroviguiepinin, which was correlated with tetrahyd     

Disoriented growth of pollen tubes of Lilium longiflorum Thunb. induced by prolonged treatment with the calcium-chelating antibiotic,chlorotetracycline

Pollen of Lilium longiflorum Thunb. was germinated for 12 h in growth medium containing 1·10^-4 M chlorotetracycline (CTC), or growing tubes were treated with 1·10^-4 M CTC for up to 2 h. These treatments have drastic effects: In the CTC-containing medium, out-growing tubes form only short tubes. Irregular wall thickenings are visible. Thirty minutes CTC-treatment cause growing tubes to bend and grow back toward the grain. Electron micrographs of CTC-treated tubes show that CTC affects the organelle distribution: The polar zonation of organelles is disturbed. Vesicle-and endoplasmic reticulum-accumulations are found in the wrong places, together with extensive wall thickenings and a very irregular plasma membrane. The structural details of most cell organelles look normal after CTC treatment, but the mitochondria possess unusual cristae, and microtubules are absent. The disoriented growth is interpreted as an effect of the ability of CTC to chelate intracellular calcium ions, to bind them to membranes, and thus to disturb the dynamics of the delicate Ca²⁺-equilibria thought to regulate oriented exocytosis.Abbreviations CTC chlorotetracycline - ER endoplasmic reticulum