Fractionation and Partial Characterization of Pectic Polysaccharides in Cell Walls from Liverwort (Marchantia polymorph) Cell Cultures

Konno, H., Yamasalu, Y. and Katoh, K. 1987. Fractionation andpartial characterization of pectic polysaccharides in cell wallsfrom liverwort (Marchantia polymorpha) cell cultures.—Jexp. Bot. 38: 711–722. Pectic polysaccharides were extracted from the starch-free cellwall preparation of cell suspension cultures of Marchantia polymorpha.The polysaccharides were fractionated by DEAE-Sephadex A-50ion-exchange chromatography yielding the five fractions, andthe degree of polymerization and glycosyl composition determinedfor each fraction. The neutral rich and acidic pectic polymerswere depolymerized by purified endoglucanase (l,4-ß-D-glucan4-glucanohydrolase, E.C. 3.2.1.4 [EC] .) and endopolygalacturonase(poly-l,4--Dgalacturonide glycanohydrolase, E.C. 3.2.1.15 [EC] ),respectively. The degraded pectic fractions were fractionatedby gel filtration chromatography on Bio-Gel A-5m and Bio-GelP-2, and glycosyl composition determined for each fraction.The results indicate that pectic polysaccharides contain glucose-richpolymer, rhamnogalacturonan and homogalacturonan in a ratioof 1:4:0–6. In addition, pectic polysaccharides were releasedas five pectic fragments from the cell walls by purified endopectatelyase (poly-l,4--D-galacturonide lyase, E.C. 4.2.2.2 [EC] ). Basedon the analysis of glycosyl composition of each fragment, thepectic polysaccharides of Marchantia cell walls are characterized Key words: Cell suspension culture, cell wall, liverwort, Marchantia polymorpha, pectic polysaccharides     

Flow cytometric assessment of cytotype distributions within local populations of Phragmites australis (Poaceae) around Lake Biwa,the largest lake in Japan

Phragmites australis (Poaceae) is a clonal perennial that is an important component of wetland ecosystems worldwide. Using flow cytometry, we examined the cytotype distributions within five populations of P. australis located in the vicinity of Lake Biwa. As in previous reports, two ploidy levels, octoploid (2n = 8x = 96) and decaploid (2n = 10x = 120), were identified, which are assumed to be the main cytotypes around the lake. The coexistence of two cytotypes was detected in four of the five populations, suggesting the relatively common occurrence of mixed ploidy levels in the populations around Lake Biwa. Although intermingled cytotype distributions were observed in some populations, the 9x cytotype, that is, the expected outcome of inter‐cytotype crosses, was not observed, indicating limited gene flow between the two cytotypes.     

Flexible social organization and high incidence of drifting in the sweat bee, Halictus scabiosae

The very diverse social systems of sweat bees make them interesting models to study social evolution. Here we focus on the dispersal behaviour and social organization of Halictus scabiosae , a common yet poorly known species of Europe. By combining field observations and genetic data, we show that females have multiple reproductive strategies, which generates a large diversity in the social structure of nests. A detailed microsatellite analysis of 60 nests revealed that 55% of the nests contained the offspring of a single female, whereas the rest had more complex social structures, with three clear cases of multiple females reproducing in the same nest and frequent occurrence of unrelated individuals. Drifting among nests was surprisingly common, as 16% of the 122 nests in the overall sample and 44% of the nests with complex social structure contained females that had genotypes consistent with being full-sisters of females sampled in other nests of the population. Drifters originated from nests with an above-average productivity and were unrelated to their nestmates, suggesting that drifting might be a strategy to avoid competition among related females. The sex-specific comparison of genetic differentiation indicated that dispersal was male-biased, which would reinforce local resource competition among females. The pattern of genetic differentiation among populations was consistent with a dynamic process of patch colonization and extinction, as expected from the unstable, anthropogenic habitat of this species. Overall, our data show that H. scabiosae varies greatly in dispersal behaviour and social organization. The surprisingly high frequency of drifters echoes recent findings in wasps and bees, calling for further investigation of the adaptive basis of drifting in the social insects.     

Anticomplementary Activity of Antitumour Polysaccharides

THE polysaccharides obtained from some basidiomycetes, Pleurotus ostreatus (Jacq. ex Fr.) Quel.¹, Flammulina velutipes (Curt, ex Fr.) Sing.², Lentinus edodes (Berk.) Sing.^2–4, Polia cocos, Wolf (Bukuryo)⁵ and Schizophyllum commune Fr.⁷, strongly inhibit the growth of sarcoma 180 and their anti-tumour activity is host-mediated^8,9.     

Micromere Differentiation in the Sea Urchin Embryo: Two-Dimensional Gel Electrophoretic Analysis of Newly Synthesized Proteins

A method for large-scale culture of isolated blastomeres of sea urchin embryos in spinner flasks was developed. Micromeres and meso-, macromeres isolated from sea urchin embryos at the 16-cell stage were cultured by this method and the patterns of protein synthesis by their descendants were examined by two-dimensional gel electrophoresis of [³⁵S] methionine-labeled proteins. Six distinct proteins with molecular weights of 140–kDa, 105–kDa, 43–kDa, 32–kDa, and 28–kDa (two components) were specifically synthesized by differentiating micromeres. Quantitative analysis of the two-dimensional gel patterns demonstrated that all these proteins, except the 32–kDa protein, appeared at the time of ingression of primary mesenchyme cells (PMC's) in vivo , several hours earlier than the onset of spicule formation. The synthesis of 32–kDa protein was paralleled to active spicule formation and the uptake of Ca²⁺. Cell-free translation products directed by poly (A)⁺ RNAs isolated from descendant cells of micromeres and meso-, macromeres were compared by two-dimensional gel electrophoresis. Several spots specific to the micromere lineage were detected. However, none of them comigrated with the proteins synthesized specifically by the cultured micromeres. The results suggest that the expression of these proteins specific to differentiating micromeres may involve post-translational modification.     

Up‐regulation of Tyrosinase Gene by Nitric Oxide in Human Melanocytes

Ultraviolet light (UV) radiation causes skin‐tanning, which is thought to be mediated by stimulating the release of melanogenic factors from keratinocytes as well as other cells. Nitric oxide (NO) has been reported to be generated after UV radiation and to stimulate melanocytes as one of the melanogens. In a previous experiment by another group on melanogenesis induced by NO, increases in both tyrosinase activity and tyrosinase protein levels were observed after daily stimulation of NO for 4 days. In the present study, we investigated tyrosinase gene expression within the first 24 hr of NO‐induced melanogenesis. Tyrosinase mRNA expression was found to be induced 2 hr after a single treatment with S‐nitroso‐N‐acetyl‐ l ‐arginine. An increase of tyrosinase activity was also detected time‐dependently within the 24‐hr period, accompanied by an increase of tyrosinase protein levels. The induction of mRNA expression was suppressed by a cyclic guanosine 3′,5′‐monophosphate (cGMP)‐dependent protein kinase (cGMP/PKG) inhibitor. These results suggest that the enhancement of tyrosinase gene expression via the cGMP pathway may be a primary mechanism for NO‐induced melanogenesis.     

A roundtable on responsible innovation with autologous stem cells in Australia,Japan and Singapore

We report on a roundtable event hosted in Singapore that sought to identify some of the ethical and regulatory challenges in translating autologous cell-based interventions, particularly those claiming to involve stem cells, into safe and effective therapies and to propose some solutions to encourage responsible innovation with these products. Challenges are identified in the three areas of cell manufacturing and processing, innovative uses of autologous cells in clinical practice and standards of evidence. Proposed solutions are discussed within a co-operative model of statutory laws and regulations that can enable product development with autologous cells and professional codes and standards that can encourage ethical conduct in clinical practice. Future research should be directed toward establishing regional networks for the development of internationally consistent standards in manufacturing and ethical codes of conduct for innovating with stem cells, and other autologous cells, and fostering ongoing exchange between jurisdictions.