Protokoll der XXI. Monatssitzung

Ohne Zusammenfassung     

Connective tissue activation. XXI

Summary The quantitative radiochemical methodology described in this report allows a major increase in information generation, increased experimental flexibility, improved statistical control, and increased diversity of information per culture. Other advantages relate to economies of technical time, supplies, cells, and test materials per individual culture. Microcultures of human synovial cells incorporate [¹⁴C]glucosamine into hyaluronic acid that accumulated primarily in the media and to a lesser extent in the cell mass. CTAP-I (from lymphoid cells), CTAP-III (from human platelets), PGE₂, dibutyryl cAMP, and poly(I)·poly(C) markedly stimulated hyaluronate synthesis, whereas cortisol, cycloheximide, and tunicamycin inhibited stimulated synthesis. Time studies with cycloheximide indicated that translation, essential for the activation of synovial cells, was completed by 17 h postexposure to CTAP-I. Tunicamycin also seemed to inhibit CTAP-I induced activation primarily by interpering with translation; however, tunicamycin also caused modest post-translational inhibition of hyaluronate synthesis in activated adult human synovial cells. Study supported by U.S. Public Health Service Grant AM-10728, the Michigan Chapter of the Arthritis Foundation, and Michigan Memorial-Phoenix Project Grant No. 517.     

Notes on Lejeuneaceae: I. Microlejeunea diversiloba (Spr.) K.M.

Abstract

Previous work on the bryophytic component of dune communities has demonstrated changes in the representation of species with the progress of succession. The ability of some to act as pioneers and the restriction of others to later stages may be associated with their reactions to recurrent burial by wind-blown sand.

Eighteen species were selected for experimental investigation of the effects of sand burial, along the following lines:

(a) Transplants. Samples of eight species were transplanted to four sites representing different stages of the dune succession. Where the sand increment over 11 months exceeded about 4 cm. none survived but species found naturally in mobile dune areas emerged from about 3 cm. Those belonging to fixed dune communities survived only in the absence of burial, although on excavation all species showed some upward growth through the covering sand.

(b) Experimental burial, Method I: samples of the same eight species, grown in pots standing in water but not watered from above, were buried in sand to depths of 1, 2, 4, 5 and 6 cm. The maximum depth through which emergence took place was 4 cm., from which Ceratodon purpureus, Bryum pendulum and Brachythecium albicans reappeared. From shallower layers, however, a greater rate of emergence was shown by Tortula ruraliformis. Pseudoscleropodiun purum and Climacium dendroides did not survive depths greater than 2 cm., and 1cm. was the maximum for Hylocomium splendns and Rhytidiadelphus squarrosus.

Method II. Sample strips of fourteen species were placed in aquarium tanks and, apart from a small portion len exposed, were buried under a sand slope grading up to 7 cm. in depth. Watering was from above and the humidity was kept high by glass lids. The time taken for the appearance of shoots from increasing depths was recorded, also the periods required for reestablishment from increasing depths of 50% and 100% of the original shoot density. For species tested by both methods the results were in most cases similar. Marked powen of recolonization were also shown by Polytrichum piliferum, P. juniperinum and Pohlia annotina.

In P. annotina, Ceratodon purpureus and Dicramum scoparium re-establishment by means of vertically extending rhizoids producing protonemata at the surface is described.

The maximum depth from which the various species can emerge, the depths from which effective recolonization of the surface is achieved within a fairly short time, the ability to produce rhizoids in the overlying sand and the growth-form of the shoots on emergence are regarded as the most significant aspects of reaction to burial, in relation to the role of the species in their natural habitats.     

XXI. Jahresbericht des botanischen Tauschvereines in Wien,im Jahre 1866

Plant Systematics and Evolution -     

Vibrational analysis of peptides,polypeptides, and proteins. XXI. β-Calcium-poly(L-glutamate)

The observed Raman and ir spectra of Ca-poly(L -glutamate) in the β conformation have been analyzed by means of a normal mode calculation. The force field for the main chain was transferred without refinement from β-poly(L -alanine), yet it provides a good prediction of the observed bands and, in particular, explains subtle differences in the spectra of these two β-sheet structures. Main- and side-chain modes are well characterized, and the dependence of the amide III frequency on side-chain composition is again demonstrated.