Index of names of syntaxa typified in 1989

Following the “Index of new names” (Theurillat etMoravec 1991a), the present work collects the names of syntaxa (in the sense of the Code of Phytosociological Nomenclature,Barkman et al. 1986) above subassociation rank typified in 1989. The list comprises 110 names of syntaxa.     

Preliminary observations on the feeding behavior ofPan paniscus in the lomako forest of central Zaïre

The feeding behavior and ecology ofPan paniscus was studied over a seven-month period in Equateur, Republic of Zaïre, during 1974–1975. Additional data were gathered during four weeks in 1979.Pan paniscus was found to be primarily frugivorous but bonobo foods also consist of leaves, flowers, pith, invertebrates and small mammals.     

Effect of canavanine and other amino acid analogues on akinete formation in the cyanobacterium Anabaena cylindrica

Addition of the arginine analogue, canavanine, to cultures of nitrogen-fixing Anabaena cylindrica at the onset of akinete formation, resulted in the development of akinetes randomly distributed within the filament, in addition to those adjacent to heterocysts. The total frequency of akinetes increased up to five-fold. A feature of akinetes is their increased content of cyanophycin granules (an arginine-aspartic acid polymer) and addition of canavanine to cultures at an earlier stage resulted in entire filaments becoming agranular and containing agranular akinetes. The effects on akinete pattern appeared to be specific for canavanine since other amino acid analogues, although increasing the frequency of akinetes (approximately two-fold), had no effect on their position relative to heterocysts. In ammonia-grown, stationary phase cultures of A. cylindrica, akinetes were observed adjacent to proheterocysts and in positions more than 20 cells from any heterocyst. These observations indicate that nitrogen fixation and heterocysts are not essential for akinete formation in A. cylindrica, although the availability of a source of fixed nitrogen does appear to be a requirement.These results suggest that during exponential growth some aspect of the physiology of vegetative cells suppresses their development into akinetes and that the role of the heterocyst may not be one of direct stimulation of adjacent vegetative cells to form akinetes, but the removal or negation of the inhibition within them. A model for akinete formation and the involvement of canavanine is given.     

Hepatocytes from newborn and weanling rats in monolayer culture: Isolation by perfusion,fibronectin-mediated adhesion,spreading, and functional activities

Summary The two-step collagenase perfusion method originally developed for the high yield isolation of parenchymal cells from adult rat livers has been adapted to rats of 1 day, 1 week, and 3 weeks of age. The use of this method to isolate hepatocytes from five or six rats of the respective ages demonstrated its reliability in terms of cell yield, percentage of single cells, and cell viability. In all cases, hepatocytes attach with high efficiency to fibronectin precoated dishes using serum-free culture medium. The dynamics of spreading is faster for newborn hepatocytes than adult ones. The functional integrity of these parenchymal liver cells was assessed by their capacity to secrete albumin and α-fetoprotein in serum-free medium and to express lactate dehydrogenase activity over a 24-hr period in primary culture. Part of this work was presented at the 30th Annual Meeting of the Tissue Culture Association, Seattle, June, 1979.     

Mode of action of a xylanase and its significance for the structural investigation of the branched l-arabino-d-glucurono-d-xylan from redwood (Sequoia sempervirens)

The substitution pattern of the water-soluble l-arabino-(4-O-methyl-d-glucurono)-d-xylan from redwood (Sequoia sempervirens) has been studied by enzymic degradation. Exhaustive hydrolysis by an endo-xylanase (EC 3.2.1.8) from a Basidiomycete Sporotrichum dimorphosporum left a residue accounting for 20% of the original d-xylan. In the dialyzable material, oligosaccharides having arabinose or 4-O-methylglucuronic acid residues attached to the non-reducing d-xylosyl end-group of xylobiose or xylotriose, respectively, were the smallest branched oligomers released. Action of the xylanase appears to involve a region of the polysaccharide backbone having three xylosyl residues. A mode of action is proposed that requires unsubstituted hydroxyl groups at C-2, C-3, and C-2′ of a xylobiosyl residue. The binding site seems to correspond to a shallow cavity. The composition and structure of the final residue of attack shows that the enzyme has no action when the xylosyl residues branched through O-2 are separated by only one, unsubstituted xylose residue. This pattern of action, the nature of the dialyzable products, and the production of a final residue in which the substituents are accumulated, suggest that the arabinosyl and glucosyl-uronic groups are irregularly distributed on the main chain of the xylan from redwood and that in some regions they are in close vicinity when not actually on adjacent xylosyl residues.     

Interaction between macrophages and Schistosoma mansoni schistosomula: Role of IgG peptides and aggregates on the modulation of β-glucuronidase release and the cytotoxicity against schistosomula

Discharge of lysosomal enzymes, measured by release of β-glucuronidase and cytotoxicity against Schistosoma mansoni schistosomula, was studied when rat macrophages were incubated in the presence of either IgG peptides, resulting from the cleavage of nonimmune IgG by parasitic proteases, or nonimmune aggregated IgG. With peptides, the macrophage activity showed a dramatic decrease while they were stimulated by IgG aggregates. In contrast, the synthesis of lymphocyte activating factor by macrophages was unaffected. The hydrolysis of IgG is carried out by two distinct enzymatic molecules released into the medium by the larvae. The mechanism by which nonimmune IgG peptides or aggregates inhibit or stimulate macrophage activity, regulated by both parameters indicated above, is discussed and is suggested as a general regulation mechanism for the macrophage activity required for parasite survival in the host.     

A new species of Asclepias (Asclepiadaceae)from Utah

Asclepias welshii, restricted to the Coral Pink Sand Dunes of southern Utah, is described and illustrated. Its relationship to other species of seriesRoseae is discussed.     

Mutations of Chinese Hamster Somatic Cells from 2-Deoxygalactose Sensitivity to Resistance

In Chinese hamster somatic cells, the spontaneous change of phenotype from 2-deoxygalactose sensitivity to resistance was studied using fluctuation test experiments à la Luria and Delbrück (1943) for four Chinese hamster cell strains derived from V79. The results are consistent with true mutational events. The mutation rates are in the range of 1 to 3.5 X 10(-5) per cell per generation. The relationship between the 2-deoxyglactose resistance and the galactokinase markers is discussed.