Further observations on the fine structure of the haptonema in prymnesium parvum

Summary Information has been provided for the first time on the fine structure of the tip and base of a haptonema, the organism being that already studied in a preliminary way in Manton and Leedale 1963 a. The tip structure is unexpectedly simple, with the haptonema cavity interposed between the rounded apex of the core and the external wall of the organelle. The base has been shown to be unexpectedly complex in that the number of core fibres, which alone enter the cell deeply, changes progressively from 7 at the surface to 9 at the extreme base. The possible meaning of these observations is discussed in a preliminary way.

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Zusammenfassung Es wird zum ersten Mal über die Feinstruktur sowohl des Endes als auch des Basalstückes eines Haptonemas berichtet. Der Organismus selbst wurde schon früher von Manton u. Leedale (1963a) untersucht. Die Struktur des Endes ist unerwartet einfach, indem der cylindrische Hohlraum des Haptonemas zwischen dem abgerundeten Apex des Zentralstückes und der Außenwand des Organelles liegt. Das Basalstück hingegen erwies sich als unerwartet kompliziert gebaut. Die Zahl der Fibrillen, die alleine ins Zellinnere eintreten, ändert sich sukzessiv von sieben an der Oberfläche auf acht und schließlich auf neun an der Basis. Die möglichen Schlußfolgerungen dieser Beobachtungen werden vorläufig diskutiert.

     

Further observations on the bacteriology of jute retting

Bacteria capable of retting jute are present in pond water, in the soil of jute fields, and on the surface of jute plants. They probably enter stems over the whole surface through stomata, as well as through cut ends and leaf scars, after immersion for retting. Under laboratory conditions the shortest period of retting, three days, was achieved withBacillus polymyxa at a temperature of 40°. Retting in a tank was appreciably hastened by using the same water for successive batches of jute. Prolonged immersion involves the risk of over-retting, probably because of the action of cellulolytic bacteria. For natural retting, still the most appropriate process in East Pakistan, large clean ponds are thought to provide the most suitable conditions.     

Further observations on the chemistry of Pararosaniline-Feulgen staining

Summary Pararosaniline-Feulgen staining of cells in suspension produces nucleus- and chromatin-specific fluorescence as well as color. Experiments were designed to test postulated reaction mechanisms responsible for the fluorescent staining with the nonfluorescent pararosaniline. The reduction in fluorescent-staining intensity by pretreatment of cells with 2.2×10⁻²M K₂S₂O₅ tends to rule out the alkysulfonic acid pathway; conditions favoring the formation of this intermediate reduce staining intensity. The fluorescence enhancement, observed when cells stained in pararosaniline without K₂S₂O₅ are post-treated with K₂S₂O₅, suggests that there is an initial Schiff-base linkage between pararosaniline and an aldehyde of hydrolyzed DNA, and that this linkage is stabilized in the presence of K₂S₂O₅. Microspectrofluorometer measurements of cells stained at various pararosaniline concentrations in 2.2×10⁻²M K₂S₂O₅, show that the fluorescence emission maximum ranges from about 627 nm at 3.1×10⁻³M pararosaniline to about 604 nm at 3.1×10⁻⁵M. All of the employed staining protocols appear to produce the same fluorescent product, perhaps a heterocyclic pyronin analog formed from pararosaniline. Flow microfluorometric analysis of cells stained in suspension verified that the relative fluorescence intensity represents relative DNA content. Staining at reduced pararosaniline concentration (3.1×10⁻⁴M) reduces the coefficient of variation of the flow microfluorometric histograms, showing that maximum quantitation does not necessarily correlate with maximum staining intensity.