Ultrastructure ofCatharanthus roseus cells culturedin vitro and exposed to conditions for alkaloid accumulation

Summary Periwinkle (Catharanthus roseus) cells cultured in 1-B 5 medium display the ultrastructure of parenchyma cells. The parenchyma character remained unchanged when cells were exposed to any one of three different conditions effecting alkaloid accumulation. Transfer of cells to alkaloid production medium for 2 weeks (condition 1) accorded two special features,i.e., unusually big lipid droplets in the cytoplasm and, upon fixation, one or several electron-dense droplets of spongy precipitate in vacuoles. Among hormone-autotrophic cultures (condition 2) some cells showed a fine electron-dense vacuolar precipitate. Addition ofPhythium homogenate (fungal elicitor) to cells cultured in 1-B 5-medium for 10 days (condition 3), cells showed a frequent appearance of singular big lipid droplets in the cytoplasm, whereas vacuoles remained devoid of precipitate. The appearance of big lipid droplets and of vacuolar precipitate is interpreted as progressing cytodifferentiation, but is coincidental with alkaloid accumulation.NRCC no. 24524.     

Gerbstoffproduktion der Calluskulturen von Juniperus communis L.

Zusammenfassung Bestimmungen des Gerbstoffgehalts in vitro kultivierter Calli von Juniperus communis L. innerhalb einer Kulturperiode von 90 Tagen ergaben ein Maximum zu Beginn der Phase stärkeren Wachstums, etwa 30 Tage nach Versuchsbeginn.Durch Veränderungen der Glucosekonzentration des Substrates wird mit der Gerbstoffproduktion gleichzeitig auch das Wachstum der Calli beeinflußt. Deshalb wird eine deutliche Zunahme des Gerbstoffgehalts erst bei einer Steigerung der Kohlenhydratkonzentration von 1 auf 6% sichtbar.

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Tannin production in the Callus cultures of Juniperus Communis L.

Summary Callus cultures of Juniperus communis L. were analysed for tannins at intervals during a period of 90 days. The tannin content (mg tannins x 100/mg dry weight) reached a maximum at the onset of rapid growth, 30 days after inoculation, and then decreased. Variation of the glucose concentration in the medium influences both the growth and the production of tannins. An increase of the tannin content can be observed only if the carbohydrate concentration is raised from 1 to 6%.

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Herrn Prof. Dr. R. Harder zum 80. Geburtstag gewidmet.     

Big flies, small repeats: the "Thr-Gly" region of the period gene in Diptera

The region of the clock gene period (per) that encodes a repetitive tract of threonine-glycine (Thr-Gly) pairs has been compared between Dipteran species both within and outside the Drosophilidae. All the non- Drosophilidae sequences in this region are short and present a remarkably stable picture compared to the Drosophilidae, in which the region is much larger and extremely variable, both in size and composition. The accelerated evolution in the repetitive region of the Drosophilidae appears to be mainly due to an expansion of two ancestral repeats, one encoding a Thr-Gly dipeptide and the other a pentapeptide rich in serine, glycine, and asparagine or threonine. In some drosophilids the expansion involves a duplication of the pentapeptide sequence, but in Drosophila pseudoobscura both the dipeptide and the pentapeptide repeats are present in larger numbers. In the nondrosophilids, however, the pentapeptide sequence is represented by one copy and the dipeptide by two copies. These observations fulfill some of the predictions of recent theoretical models that have simulated the evolution of repetitive sequences.      

Alkaloid production in Catharanthus roseus (L.) G. Don.

Analysis of 76 cell clones derived from one leaf of a periwinkle plant (Catharanthus roseus (L.) G. Don) showed the occurrence of Corynanthe-, Strychnos-, and Aspidosperma-type alkaloids. The majority of clones (62%) displayed compounds of all three types. Variation of the alkaloid spectra of the cell clones was low when compared to that found previously with serially subcultured callus and cell suspensions derived from different plants.NRCC # 19100     

Electron-microscope observations of mitosis and cytokinesis in multinucleate protoplasts of soybean.

Multinucleate soybean protoplasts produced by spontaneous fusion during enzyme digestion of the cell wall initiated cell division after approximately 40 h in culture. The structure of these protoplasts during mitosis and cytokinesis was studied with both light and electron microscopes. Most nuclei did not fuse but divided synchronously. Interphase nuclei was commonly connected by short narrow nuclear bridges. At prophase and metaphase the nuclei appeared typical of those in most higher plants; technical difficulties prevented an adequate examination of protoplasts at anaphase. Telophase was characterized by cytokinesis involving phragmoplast and cell plate formation; however, complete partitioning of the cytoplasm by cell plants was not observed. Numerous coated vesicles were present near to or continuous with the cell plate and plasmalemma. The presence of a few dividing protoplasts with at least double the normal chromosome number suggests that some nuclear fusion occurred prior to mitosis. Very little cell wall material was detected at the margin of the dividing protoplasts.