Analysis of the disassortative mating pattern in a heterodichogamous plant, <Emphasis Type="Italic">Acer mono</Emphasis> Maxim. using microsatellite markers

Heterodichogamy is a form of sex expression in which protandrous and protogynous individuals coexist, and is considered to be a mechanism that avoids selfing and promotes disassortative mating. We examined mating patterns in a heterodichogamous maple, Acer mono, using microsatellite markers. Parentage analysis revealed a selfing rate of only 9.8%. Disassortative mating between flowering types significantly exceeded within-type mating, but the mating patterns were better explained by flowering phenology (i.e., the temporal overlap between the female and male stages). Heterodichogamy in A. mono thus appears to promote outcrossing without requiring obligate self- or cross-incompatibility systems, although it did not guarantee disassortative mating. Multiple-regression analysis suggested that successful reproduction of pollen parents significantly increased with increased flower production and reciprocal flowering synchrony, but decreased only marginally with mating distance, although the distribution of mating distances suggested leptokurtic dispersal of pollen.     

Fixative-Stain Sequences for Selective Demonstration of Juxtaglomerular Cells

The effects of 31 fixatives, containing alcohol, acids, formalin and metallic salts, and representing many of the standard fixatives, were observed for selectivity and intensity of staining of juxtaglomerular granules in mouse kidney. Four staining methods: 1:400,000 aqueous methyl violet 2B; Bowie's ethyl violet-Biebrich scarlet; 1:200,000 aldehyde fuchsin; and periodic acid-Schiff were used. Fixatives containing HgCl₂, trichloroacetic acid or formalin were found to be the most satisfactory for subsequent staining of the granules.     

Identification and characterization of a cathepsin B-like protease in Physarum sclerotium

In response to dry stress the plasmodium of a true slime mold, Physarum polycephalum, undergoes formation of sclerotium, which is a dormant body resistant to desiccation. The sclerotium can germinate within several hours after addition of water, followed by generation of the plasmodium. In the early phase of the germination many enzymes and other proteins of the sclerotium are required for formation of the plasmodium. As dehydration of proteins often leads to destruction of their structure or reduction in their activity, it is important to elucidate whether the dehydrated enzymes are present as the intact in the sclerotium. In this study three peaks of protease activity were detected with anion exchange column chromatography of the extract from the sclerotia. From among them, an acid protease was purified to homogeneity by gel filtration column chromatography, hydroxyapatite column chromatography, acid treatment, and cation-exchange column chromatography. Treatment of the protease fractions with pH 4.0 resulted in approximately 20-fold activation of the activity. The purified protease was a monomer with a molecular mass of 35 kDa. The optimum pH and temperature were 6.3 and 40 degrees C, respectively. Beta-casein, histone H1, and H2B were degraded by the 35 kDa protease, but human hemoglobin and human serum albumin were very poor substrates. In addition, the enzyme was sensitive to the cysteine protease inhibitors chymostatin, E-64, and leupeptin. These results indicate that, in the sclerotium, a premature form of a cathepsin B-like protease remains non-denatured under dehydrated conditions.     

Isolation and Characterization of an Enterobacter cloacae Strain That Reduces Hexavalent Chromium under Anaerobic Conditions

An Enterobacter cloacae strain (HO1) capable of reducing hexavalent chromium (chromate) was isolated from activated sludge. This bacterium was resistant to chromate under both aerobic and anaerobic conditions. Only the anaerobic culture of the E. cloacae isolate showed chromate reduction. In the anaerobic culture, yellow turned white with chromate and the turbidity increased as the reduction proceeded, suggesting that insoluble chromium hydroxide was formed. E. cloacae is likely to utilize toxic chromate as an electron acceptor anaerobically because (i) the anaerobic growth of E. cloacae HO1 accompanied the decrease of toxic chromate in culture medium, (ii) the chromate-reducing activity was rapidly inhibited by oxygen, and (iii) the reduction occurred more rapidly in glycerol- or acetate-grown cells than in glucose-grown cells. The chromate reduction in E. cloacae HO1 was observed at pH 6.0 to 8.5 (optimum pH, 7.0) and at 10 to 40°C (optimum, 30°C).     

Chemical ionization-mass spectra of aldobiouronic acids and dialdose dianhydrides

Chemical ionization (c.i.) mass spectra with isobutane as the reagent gas are reported for the peracetates of aldobiouronic acids and related compounds, and for peracetates and permethylated derivatives of dialdose dianhydrides. Ions (M⁺ + 43) having relatively high intensities were detected in the spectra of disaccharides lacking the dianhydride structure. Peracetylated dialdose dianhydrides showed very weak (M⁺ + 43) ions, and permethylated dianhydrides did not show them. The (M⁺ + 43) ion consisted of molecular ion and acetoxyl radical (but not of the reagent gas). In the c.i. mass spectra of the usual disaccharide peracetates, (M⁺ ? 31) and (M⁺ ? 60) ions had large intensities. In contrast, c.i. mass spectra extremely similar to the corresponding e.i. mass spectra were obtained for dialdose dianhydrides.     

Studies on fungal polysaccharide XVII. A new glucuronan “protuberic acid” produced by a fungus Kobayashi Nipponica

A water-soluble glucuronan “protuberic acid”, [α]_d²² −83.6° and purified from Kobayashia Nipponica, and its physicochemical properties were investigated.The purified protuberic acid was homogeneous as shown by zone electrophoresis, gel filtration over Sepharose 4B, and ultracentrifugation. The sedimentation coefficient was 1.8 S and its intrinsic viscosity was 1.1 dl/g. By gel filtration the molecular weight was estimated to be about 170 000. The results of periodate oxidation, methylation analysis, and partial acid hydrolysis indicated that this acidic polysaccharide has a linear structure of mainly 1,4-linkages and containing an acid-labile linkage. Reduced protuberic acid, [α]_d²² −44°, is also described.     

Vegetation patterns in relation to micro-scale landforms in hilly land regions

Spatial structures of landforms as constants affecting vegetation patterns are discussed based on analyses of hilly land regions, mostly in the vicinity of Sendai, northeast Japan. The lower part of a hillslope is characterized by relatively active processes of soil erosion, landslides and slope failure. It supports a plant community different from that on the upper part of the hillslope. These two parts are termed the lower hillslope and the upper hillslope, respectively. The upper hillslope consists of valley heads with no stream water nor stream channels. Since a valley head is comprised of several micro-scale landform units, an upper hillslope can be subdivided into these landform units. Plant communities vary in their species compositions and structures as well as in some other ecological characteristics paralleling changes in their respective micro-scale landform units. However, the variations in species composition within upper hillslopes are not as extreme as those between the upper and lower hillslopes. xx]Papers presented at the Vth INTECOL Congress at YOKO-hama 1990.