Morphology and biochemical genetics of Atlantic halibut, Hippoglossus hippoglossus (L.), from various spawning grounds

Potential phenotypic/genotypic differentiation of Atlantic halibut, Hippoglossus hippoglossus (L.), samples from two spawning grounds in north Norway (Malangen and Sørøysund) were studied. In addition, the genetic relationship between fish from north Norway, mid–Norway (Folia) and western Greenland (off Fredrikshåb) was investigated. Uni– and multivariate analyses of 15 morphometric measurements and six meristic counts revealed a considerable degree of homogeneity between Malangen and Sørøysund. No morphological characters were thus found suitable as diagnostic tools in the classification of potential halibut stocks. As determined from electrophoretic studies, the allelic distribution at the four polymorphic loci ADA, PGI–2, PGM–2 , and UTP (unidentified tissue protein) did not vary significantly when all four samples (Folia, Malangen, Sørøysund and Greenland) were considered together. However, when the Norwegian coast samples were split into a northern (Sørøysund and Malangen) and a middle (Folla) area, and each locus was regarded isolated, significant heterogeneity was detected at the PGM–2 locus, thus giving evidence for a potential heterogeneity along a north–south axis.     

Aluminum interaction with calmodulin. Evidence for altered structure and function from optical and enzymatic studies

The interaction of aluminum ions with bovine brain calmodulin has been examined by fluorescence spectroscopy, circular dichroic spectrophotometry and equilibrium dialysis, and by the calmodulin-dependent activation of 3',5'-cyclic nucleotide phosphodiesterase. These experiments show that aluminum binds stoichiometrically and cooperatively to calmodulin. Binding of aluminum at a molar ratio of 2:1 to calmodulin suffices to induce a major structural change. Estimates from spectroscopic data indicate that the binding affinity for the first mol of aluminum bound to the protein is about one order of magnitude stronger than that of calcium to its comparable site. These estimates agree with a dissociation constant of 0.4 microM derived from equilibrium dialysis experiments. Interaction of aluminum with calmodulin induces a helix-coil transition and enhances the hydrophobic surface area much more than calcium does. A molar ratio of 4:1 for [aluminum]/[calmodulin] is sufficient to block completely the activity of the calcium-calmodulin-dependent phosphodiesterase. Highly hydrated aluminum ions apparently promote solvent-rich, disordered polypeptide regions in calmodulin which, in turn, profoundly influence the protein's flexibility.     

Morphometrie der feinen Markfasern in der Sehrinde der Katze

Zusammenfassung In den Schichten I bis III der Sehrinde der Katze wurden die feinen markhaltigen Nervenfasern morphometrisch untersucht. Folgende Größen wurden bestimmt: 1. mit Hilfe des Punktzählverfahrens ein Volumenanteil von 7,1±1,6%. 2. Mit der Methode von Hennig (1958) in einem Raum von (0,1 mm)³ eine Oberfläche von 0,42±0,07 mm². 3. Mit Hilfe der Methode von Hennig (1963) in einem gleichen Raum eine Summenlänge der Markfasern von 152 mm. 4. Bei 3693 markhaltigen Nervenfasern ein Mittelwert aller Durchmesser von 0,51±0,08 . Die Größenverteilung der Durchmesser ist in der Abb. 2 enthalten. 5. Die Ergebnisse von 3. und 4. erlaubten eine Kontrollberechnung von Volumenanteil und Oberfläche. Die mit unterschiedlichen Methoden ermittelten Ergebnisse zeigen eine gute Übereinstimmung.

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Summary The small myelinated axons in layers I to III of the cat's visual cortex have been investigated by means of morphometric methods. It has been found that: 1. The myelinated fibres make up 7.1±1.6% of the total volume. 2. Within a volume of (0.1 mm)³ the myelinated fibres have a surface of 0.42±0.07 mm². 3. The compound length of the myelinated fibres within a volume of (0.1 mm)³ is 152 mm. 4. The diameters of 3,693 myelinated fibres have a mean value of 0.51±0.08 . The distribution of the diameters is shown in Fig. 2. 5. The results of 3. and 4. can be used to control the values given in 1. and 2. The values obtained by the two different methods are in good agreement.

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Die Untersuchungen wurden mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft ausgeführt.     

Triplex DNA in plasmids and chromosomes

Circular plasmids containing pyrimidine purine tracts can form both inter-and intramolecular triplexes. Addition of poly(dTC) to plasmid pTC45, which contains a (TC)45.(GA)45 insert, results in intermolecular triplex formation. Agarose-gel electrophoresis gives rise to many well-resolved bands, which correspond to 1, 2, 3, 4... plasmid molecules attached to the added pyrimidine strand. In the electron microscope these complexes appear as a rosette of petals. The mobility of these triplex-containing complexes can be retarded by the addition of a triplex-specific monoclonal antibody, Jel318. Intramolecular triplex formation can be demonstrated at pH 5 in pTC45 and also in pT463-I, a plasmid containing a segment of a crab satellite DNA with both (G)n.(C)n and (TCC)n.(GGA)n inserts. However, although the intermolecular triplex remains stable for some time at pH 8, intramolecular triplex formation only occurs at low pH. Triplexes can also be detected by an immunoblotting procedure with Jel318. This unfamiliar structure is readily demonstrated in eukaryotic extracts, but not in cell extracts from Escherichia coli. Triplexes may thus be an inherent feature of eukaryotic chromosome structure.     

Die histologischen Vorgänge während der lichtabhängigen Schliessung und Öffnung des Plumulahakens bei den Keimlingen vonLactuca sativa L.

Summary In a preceding paper the following facts have been shown (Mohr undNoblé 1960): Dark grown seedlings ofLactuca sativa L. var.Grand Rapids (tip burn resistant strain) do not form an appreciable plumular hook. But a normal plumular hook, as is formed for instance byPhaseolus vulgaris in complete darkness, can be induced by red light. This formation of the plumular hook is controlled by the phytochrome system. — The hook which has been closed by red radiation can be reopened by light. In this respect only the high energy reaction of photomorphogenesis is effective. This reaction system shows peaks of action in the blue and in the far-red part of the visible spectrum (cf.Mohr 1962).The present paper deals with the investigation of the anatomical and cellular changes which lead to hook formation and reopening. The movements of the hook always take place in the cotyledonary plane. Bending of the hook accurs because the cells on the potentially outer side of the future hook increase their rate of elongation, unbending of the hook is due to a rapid increase in rate of elongation of the cells on the inner side of the closed hook. Cell dividions are apparently not involved either in the bending or in the unbending of the hook. It is concluded, that the apical part of the hypocotyl is a highly complex organ the potentialities of which can be described only with the help of physiological experimentation. The conventional anatomical or cytological approaches are not adequate to describe in detail the pattern of differentiation which must be present in the apical part of the hypocotyl according to the reactions which can be induced by light.

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Mit 13 Textabbildungen

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Als Plumulahaken (=plumular hook) bezeichnen wir die auffällige Einkrümmungszone im Apikalbereich einer Keimpflanze. Ein knapper und klarer Begriff hat sich offenbar in der deutschen Literatur nicht durchgesetzt. AuchTroll (1959) spricht nur allgemein von einer apikalen Krümmung des Keimsprosses. Bei dem Plumulahaken derLactuca-Keimlinge handelt es sich um eine Einkrümmung des apikalen Hypokotylbereichs.     

Electron spin resonance study of the isolated lipid components from Blastocladiella emersonii zoospores

The physical properties of the plasma membrane of the aquatic phycomycete Blastocladiella emersonii were investigated, in particular the effects of cations on membrane structure. Intact zoospores and lipid extracts were labelled with the spin-labels 5-nitroxystearate (5-NS), 12-nitroxystearate (12-NS), and 2,2,6,6-tetramethylpiperidine-1-oxyl (Tempo). Electron spin resonance spectroscopy indicated a total of three breaks in plots of the hyperfine splitting parameter, 2T_|, order parameter, S, and the partition coefficient, f, vs. temperature. The first and third break points (T_L and T_H) were found to be independent of the external K⁺, Ca²⁺, or Mg²⁺ concentrations. They were similar to the break points found in aqueous dispersions of lipid extracts and correlate well with the temperature limits for zoospore viability. In contrast, the middle break point (T_M) was markedly influenced by the external Ca²⁺ concentration. Ca²⁺ increased T_M from 12°C (no Ca²⁺ added) to 22°C (10 mM Ca²⁺), i.e., growth temperature. K⁺ reversed this Ca²⁺ effect, downshifting T_M from 22°C to 10°C. A comparison of the physico-chemical effects of these ions on the membrane, as revealed by the cation-induced shift in T_M, is closely correlated with the temperature dependence and physiological effects of cations on zoospore differentiation. This suggests that cations may modify the physical state of the plasma membrane and be involved in regulating the initial changes during zoospore encystment.