An EPR study of structural perturbations induced by methylindole in the protein and lipid regions of erythrocyte membranes.

3-Methylindole has been shown in previous work to cause pulmonary edema and emphysema in cattle and goats. In this paper, evidence is presented to show that 3-methylindole induces structural perturbations in bovine erythrocyte membranes. The structural perturbations which were induced as a function of 3-methylindole concentration in the membranes were measured by EPR using the attachment of maleimide spin label to the sulfhydryl groups of membrane proteins and by intercalation of methyl-5- doxylstearate, methyl-12-doxylstearate, and methyl-16-doxylstearate into the lipid region. The EPR spectra of the malemide spin-labeled membrane proteins became more immobilized as the concentration of 3-methyl-indole increased. The order parameter describing the EPR spectra of methyl-5-doxylstearate decreased from 0.69 to 0.55 as the concentration of 3-methylindole increased. The acyl chains in the region of the carbon 5 position were converted to a less ordered structure. The EPR-spectra of methyl-12-doxylstearate was a superposition representing at least three tumbling rates. As the concentration of 3-methylindole increased, the major fraction of the methyl-12-doxylstearate probes experienced an increase in tumbling rate and a smaller fraction is observed a strongly immobilized state. The EPR spectra of methyl-16-doxylstearate were not perceptibly changed in the presence of 3-methylindole. The concentration dependence suggests that 3-methylindole preferentially intercalates into the ordered region of the alkyl chains sampled by the methyl-5-doxylstearate. These results confirm that 3-methylindole induced structural changes at the molecular level.     

Reversible reaction of cyanate with a reactive sulfhydryl group at the glutamine binding site of carbamyl phosphate synthetase.

Carbamyl phosphate synthetase from Escherichia coli reacts stoichiometrically (one to one) with [14C]cyanate to give a 14C-labeled complex which can be isolated by gel filtration. The formation of the complex is prevented if L-glutamine is present or if the enzyme is first reacted with 2-amino-4-oxo-5-chloropentanoic acid, a chloro ketone analog of glutamine which has been shown to react with a specific SH group in the glutamine binding site. The rate of complex formation is increased by ADP and decreased by ATP and HCO3-. The isolated complex is inactive with respect to glutamine-dependent synthetase activity. However, the reaction of cyanate with the enzyme is reversible. The rate of dissociation of the isolated complex is not affected by pH (over the pH range 6-10), is greatly increased by ATP and HCO3-, and is decreased by ADP. The allosteric effectors ornithine and UMP have no effect on either the rate of formation or the rate of dissociation of the complex; however, the apparent affinity of the enzyme for ATP is decreased by UMP and increased by ornithine. The site of reaction of cyanate with carbamyl phosphate synthetase, which is composed of a light and a heavy subunit, is with an SH group in the light subunit to give an S-carbamylcysteine residue. The binding of L-[14C]glutamine to the enzyme and the inhibition of glutamine-dependent synthetase activity by the chloroketone analog are both prevented by the presence of cyanate. The reaction with cyanate is considered to be with the same essential SH group which is located in the glutamine binding site and is alkylated by 2-amino-4-oxo-5-chloropentanoic acid. The bicarbonate-dependent effects of ATP suggest that formation of the activated carbon dioxide intermediate is accompanied by changes in the heavy subunit which functionally alter the properties of the glutamine binding site on the light subunit. The allosteric effects of ornithine and UMP are probably not related to this intersubunit interaction.     

The housefly interfacetal hair

The external and internal fine structure of the housefly interfacetal hair and its sensory dendrite was studied with the scanning and transmission (high and low voltage) electron microscopes. The hair shaft contains no dendrites, and is usually situated within a socket on the lens surface. Immediately beneath and directly connected to the base of each hair is a bipolar neuron whose dendrite tip is enveloped in a shealth cell which, in turn, is surrounded by a second sheath cell. Septate junctions are seen between all these cells and contiguous portions of a large pigment cell. At the hair base, the dendrite of the neuron terminates in a tubular body only 1.5 mum in diameter which is filled with about 400 microtubules in highly ordered (in parallel pentagonal and hexagonal) arrays and whose sides are fused to neurofilaments in parallel. Another filament (ca. 70 A diameter) is in the center of each microtubule-neurofilament polygon. Structures proximal to the tubular body are typical for a scolopoid sensillum, i.e., connecting cilium (9 times 2 + 0 microtubules) with rootlet and basal bodies, unmodified dendrite, perikaryon and axon. The axon has not been traced to its synapse. The high degree of internal organization and shortness of the tubular body, as well as its eccentric insertion into the hair shaft lead to the hypothesis that this hair may be a highly sensitive mechanoreceptor. On the basis of their single innervation, these hairs could monitor flight speed from the degree of hair deflection caused by wind in general or particular laminar air currents flowing past the eyes during flight.     

Bemerkungen zur Veränderlichkeit und Streuung von Seegangsbeobachtungen im Flachwasserbereich

Zusammenfassung 1. Betrachtet werden Wellenmessungen mit Schwimmergeräten an Meßpfählen vor den deutschen Küsten. Die nach Beobachtungsstellen und in Klassen annähernd einheitlicher Windrichtung und -stärke geordneten Wellengrößen unterliegen einer sehr starken Streuung. Dies wird an Beispielen gezeigt, wobei Gründe angegeben werden.2. Mittelwerte pro Windklasse streuen gleichfalls, weil die Zahl der Beobachtungen pro Klasse in den meisten Fällen zu gering ist.3. Kritisiert wird eine vonGienapp (1972) verwendete Methode; mit ihr wurden für Windklassen, für die keine Wellenbeobachtungen vorliegen, Wellengrößen durch Ausgleichung und Extrapolation abgeleitet.4. Schließlich wird vorgeschlagen, nur Messungen bei ausgewählten Wetterlagen auszuwerten bzw. in Zukunft nur bei bestimmten, ausgewählten Windsituationen zu messen.

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Remarks on variability and scattering of wave observations in shallow water areas

Wave data, obtained by measurements off the coast of the Federal Republic of Germany scatter very strongly, even within classes of uniform wind conditions present at measuring time. The reasons for the considerable scatter are enumerated and discussed. The method used byGienapp (1972) for deriving wave properties from strong winds by extrapolation is criticized. It is proposed to conduct wave measurements only during selected, defined weather situations.

     

Surface fine structure of the eye of the housefly (Musca domestica): Ommatidia and lamina ganglionaris

Summary The compound eye of the housefly, from lens to first optic neuropile (lamina ganglionaris) was examined with a scanning electron microscope. Key findings are as follows: The pseudocone cavity is enclosed by six corneal pigment cells. The nuclei of the six cells are firmly anchored to the underside of the lens and portions remain after lens delamination from the pseudocone cavity. An eccentrically-positioned, short photoreceptor cell was observed near the region where the inferior central cell initiates its rhabdom. This eminence may represent that cell's soma. The basement membrane is revealed as a two-tiered, fibrous layer with ovoid fenestrations. Each opening is sealed with a diaphragm perforated by eight retinular axons and a trachea. Conjoined distal surfaces of the satellite glial cells form a membrane-like barrier immediately underlying the basement membrane. Monopolar somata from the lamina are covered with glial cells which possibly make more intimate contact with the somata through miniscule projections. Optic cartridges with monopolar interneurons were noted. Spherical to slightly biconcave processes of these interneurons contact retinular axons. Very fine (1000 Å) filaments interweave among and contact lateral processes. Further implications are discussed as they relate to observed structures.We gratefully acknowledge research support from the Graduate School, University of Wisconsin, Project No. 140508. Mr. Jack Rozental kindly supplied an English translation of the Cajal and Sanchez (1915) treatise on the fly nervous system. Dr. N. J. Strausfeld, Max Planck Institut für biologische Kybernetik, Tübingen, graciously provided comments about the figures.     

Initial Heat Production in Isometric Frog Muscle at 15°C

An infrared radiation-detecting system was used to measure initial heat production in bull frog sartorius muscle at 15°C. Numerous tests with the system showed that thermal artifacts were not noticeable. Many previous measurements with myothermic thermopiles were corroborated with this method. In addition, a cooling phase as large as 0.39 of peak exothermicity was found during and after relaxation. Cooling diminished with both increasing sarcomere length and increasing duration of mechanical activity. No large rapid increase in heat rate accompanied a 0.6 reactivation at the peak of twitch tension. Above rest length, initial heat rate and the heat produced up to the peak of tension decreased nearly proportionally with overlap of myofilaments, while the total twitch initial heat decreased slightly.     

Minor and trace sterols in marine invertebrates. 1. General methods of analysis.

3beta-Hydroxy sterols occurring at a concentration of at least 0.001% of the sterol mixtures of Pseudoplexaura porosa and Plexaura homomalla have been fractionated using a series of refined techniques and subsequently analyzed using combined gas chromatography-mass spectrometry (GC-MS) in the development of a procedure for examining the minor and trace components of marine sterol mixtures. A total of 49 sterols were found which spanned a molecular weight range of 274 to 440. In addition delta4-3-keto analogs of cholesterol, 24-methylcholesterol and gorgosterol were found in the extracts of P. homomalla. Initial separation of various natural sterol-containing conjugates and free sterols was found to have a number of advantages. Fractional digitonin precipitation and alumina column chromatography were found to possess greater sterol separation abilities than previously recognized. Many of the minor sterols were found to possess novel structures including a series of short side chain sterols, 19-nor sterols, 5beta-stanols and 4-monomethyl sterols for which structure elucidation work is continuing.