Der Bestand vonCalanus finmarchicus in der Irminger See im Juni 1955

Zusammenfassung 1. Von den drei morphologisch unterschiedenen und zuweilen als Arten voneinander getrennten Formen des CopepodenCalanus finmarchicus s. 1. tritthelgolandicus (Claus) nur im Südosten des Untersuchungsgebietes im Nordostatlantischen Wasser auf,glacialis Yashnov ist auf das Ostgrönland-Wasser jenseits der Polarfront beschränkt, kommt aber vereinzelt auch im Tiefenwasser der Irminger See vor, währendfinmarchicus (Gunnerus) s. str. über das ganze Gebiet verbreitet ist und im Irminger-See-Wasser und dem angrenzenden Mischwasser reine Bestände bildet.2. Das Vorkommen intermediärer Formen in den Grenzgebieten sowie die großen, sich teilweise überlagernden Variationsbreiten der Merkmale lassen vermuten, daß die genannten Formen genetisch nicht streng isoliert, sondern als geographische Rassen einer plastischen ArtC. finmarchicus s. l. miteinander verbunden sind.3. Der Bestand derfinmarchicus-Rasse ist in mehrere Populationen aufgeteilt, die sich in ihrer mittleren Körpergröße und dem Entwicklungsgrad unterscheiden. Ihre Verbreitungsareale entsprechen weitgehend der hydrographischen Gliederung der Wasserkörper.4. In den Gebieten diesseits der Polarfront mit großen jahreszeitlichen Schwankungen der Temperatur besteht eine negative Korrelation zwischen der Länge der ausgewachsenen und auch jüngeren Stadien einerseits, und den örtlichen Temperaturverhältnissen andererseits. Derartige Beziehungen fehlen dagegen in den Gebieten jenseits der Polarfront mit kleiner Jahresamplitude der Temperaturschwankungen. Tiere, die durch Verdriftung oder Vermischungsvorgänge unter andere Milieuverhältnisse geraten, behalten ihr ursprüngliches Längenwachstum bei.5. Dieses unterschiedliche Verhalten gegenüber der Temperatur macht es wahrscheinlich, daß beiCalanus finmarchicus das Längenwachstum zu einem sehr frühen Zeitpunkt der Entwicklung im wesentlichen determiniert wird.

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The stock ofCalanus finmarchicus in the Irminger Sea in June 1955

During the cruise of the Fisheries Research vessel Anton Dohrn in the Irminger Sea in June 1955, the morphological and physiological composition of the stock of the copepodCalanus finmarchicus (Gunnerus) sensu lato was studied. The formhelgolandicus is restricted to the Northeast Atlantic water body, the formglacialis to the East Greenland water body, whereasfinmarchicus sensu stricto is distributed throughout the whole area. In regard to the wide variation ranges of the morphological distinctive traits and to the occurrence of intermediate forms in the border districts, the forms, hitherto described as species, are regarded as geographical races. The stock ofC. finmarchicus s. str. is divided into several populations, which differ one from another in their medium size. InC. finmarchicus, the size of adults and earlier stages is negatively related to the temperature; this correlation is lacking in populations which drifted under different temperature conditions. The distribution of the forms and populations correspond to the hydrographical and planktological pattern.

     

Evidence for the Presence of Chlorophyllide b in the Green Alga Scenedesmus obliquus in vivo

Chlorophyllide b could be extracted from the wild type of Scenedesmus obliquus and its pigment mutant C-2A'. Its identity was proved by absorption and fluorescence spectroscopy and by a positive hydroxylamine test. Chlorophyllide b could be transformed into pheophorbide b and methylpheophorbide b. The formation of chlorophyllide b from chlorophyll b by dephytylation with chlorophyllase could be ruled out. The stimulation of chlorophyllide b biosynthesis with o-phenanthroline, as described in the literature, could not be confirmed under physiological conditions.     

Fermentation of potato mash,potato mash/maltrin mixtures,maltrin and wheat starch usingZymomonas mobilis

Summary Potato mash, potato mash/maltrin mixtures, maltrin and wheat starch have been fermented with 95 to 98% conversion efficiencies. Highest ethanol yields obtained were 13.5% (v/v) in 24 h. The addition of 20% backset (= thin stillage) or change of pre-culture conditions did not affect the process.

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Fermentation de purée de pommes de terre seule et en mélange avec la maltrine, de maltrine seule et d'amidon de froment par Zymomonas mobilis

Résumé On fermente la purée de pommes de terre seule et en mélange avec la maltrine ainsi que l'amidon de froment jusqu'à 95 à 98% d'efficacité de conversion. Les rendements les plus élevés en éthanol sont de 13.5% (v/v) en 24 h. Le recyclage de 20% de résidu fluide de fermentation ou le changement des conditions de préculture n'affectent pas le processus.

     

How does inactivation change timing of replication in the human X chromosome?

Summary The kinetics of replication of the inactive (late replicating) X chromosome (LRX) were studied in karyotypically normal lymphocytes and human amniotic fluid cells. Both cell types were successively pulse labeled with 1-h or 1/2-h thymidine pulses in an otherwise BrdU-substituted S phase after partial synchronization of the cultures at G₁/S. For the first time with this technique, the entire sequence of replication was analyzed for the LRX from the beginning to the end of the S phase, with special reference to mid S (R-band to G-band transition replication). The inactive X is the last chromosome of the metaphase to start replication, with a delay of 1 or 2h, after which time a thymidine pulse results in R-type patterns. In mid S, the inactive X is the first chromosome to switch to G-type replication (without overlapping of both types and without any detectable replication pause). Until the end of S, a thymidine pulse results in G-type patterns. To rule out artifacts that might arise by the synchronization of cultures in these experiments, controls were carried out with BrdU pulses and the BrdU antibody technique without synchronization. In the course of replication, no fundamental difference was seen between the two different cell types examined. In contrast to studies using continuos labeling, this study did not reveal an interindividual difference of replication kinetics in the LRXs of the seven individuals studied; thus it is concluded that the inactive X chromosome shows only one characteristic course of replication.     

Electron spin resonance evidence for the formation of free radicals in plants exposed to ozone

Electron spin resonance (ESR) spectroscopy was used to demonstrate that free radicals are formed in O₃-fumigated plant leaves prior to the formation of visible leaf injury. ESR signals with a g-value of 2.0037 to 2.0043, were observed in pea ( Pisum sativum L. cv. Feltham first) and bean ( Phaseolus vulgaris L. cv. Pinto) plants that had been fumigated for 4 h with 70–300 nl l⁻¹ of ozone after they had been treated with the spin-trap N- t -butyl-α-phenylnitrone (PBN). The size of the ESR signals increased with the concentration of ozone used but the nature of the trapped radicals could not be identified. However, further experiments using an inhibitor of ethylene biosynthesis, arninoethoxyvinyl glycine (AVG), showed that the reaction between ozone and ethylene is the cause for ozone toxicity.     

Mechanical impedance increases aluminium tolerance of soybean (Glycine max) roots

The effect of aluminium (Al) on root elongation was studied in solution culture and sand culture. Compared to solution culture, in sand culture a ten times higher Al supply was necessary to inhibit root elongation to a comparable degree. This was due to a much lower Al uptake into the 5 mm root tips in sand culture. Fe concentrations in root tips were also lower in sand culture. Ca concentrations were higher and less depressed by Al, whereas Mg and K concentrations were not affected by the culture substrate. Regressions of Al concentrations in root tips versus inhibition of root elongation by Al revealed root damage at lower Al concentrations in sand culture. The effect of culture substrate on Al tolerance was independent of N source and could also be shown in flowing solution culture with and without sand. The results indicate that mechanical impedance in sand culture decreased Al uptake. This may be due to enhanced exudation of organic complexors thus reducing activites of monomeric Al species.