Scanning Electron Microscopic Observation of Differentiation from the Reproductive Short Form to the Infectious Long Form of Holospora obtusa

To identify the surface features of Holospora obtusa during its differentiation from the reproductive short form to the infectious long form, bacteria of four different buoyant densities were isolated by Percoll density gradient centrifugation of homogenates of host cells or isolated macronuclei, and examined with a scanning electron microscope. Bacteria of buoyant density 1.09 g/ml were reproductive short forms as well as cells at various stages in the elongation process including fully elongated ones. Bacteria of buoyant densities 1.11 g/ml and 1.13 g/ml were premature long forms and those of 1.16 g/ml were mature infectious long forms. Bacteria of buoyant density 1.09 g/ml had an entirely rough surface while those of buoyant densities 1.11 g/ml and 1.13 g/ml were smooth and had wale-like stripes on their surface. A small tapered tip was observed at one end of the bacteria of buoyant density 1.13 g/ml. Bacteria of buoyant density 1.16 g/ml had an entirely smooth surface, but one end always showed a rough surface; this locally differentiated surface of the special tip of the infectious long form may be responsible for both the nuclear and species specificities of the infectivity of H. obtusa. These observations indicate that the surface of H. obtusa changes during differentiation and the special tip develops in bacteria of buoyant density 1.13 g/ml.     

Developmental morphology of foliose shoots and seedlings of Dalzellia zeylanica (Podostemaceae) with special reference to their meristems

The developmental morphology of seedlings and shoots of Dalzellia zeylanica was examined with reference to the meristem in order to understand the dorsiventral, foliose shoot. In seedlings, no obvious primary shoot and no root are formed. Subsequent to disappearance of the vestigial primary shoot meristem, two shoot meristems are established in the axils of the cotyledons, one of which grows into a secondary shoot. Microtome and SEM examinations of mature plants show that the shoot meristem is complex, comprising three zones along the shoot margin. The organogenetic zone, equivalent to the shoot apical meristem, produces dorsal leaves proximally and much fewer marginal leaves distally. During development, the zone repeatedly changes into a dorsal zone, while a new organogenetic zone is formed in an area between developing marginal leaves, resulting in the alternation of the organogenetic and dorsal zones, which allowed development of the coenosomic structure of the shoot. The dorsal and ventral zones do not produce leaves, but contribute to shoot expansion. The ventral zone also forces the marginal leaves to shift to the lateral side of the shoot. The rosette with tufted leaves might be a modification of the short shoot (ramulus) of other Tristichoideae.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 289–302.     

角蒿生物碱及镇痛活性物质

角蒿(Incarvillea sinensis)为透骨草的主要来源之一,称为“羊角透骨草”,具有祛风除湿、消肿止痛之功效。从其全草分离得到了多种新的单萜生物碱和大环精胺类生物碱,其中单萜生物碱之一角蒿酯碱(incarvillateine),具有很强的镇痛活性,且作用机理不同于吗啡。角蒿酯碱已成为开发新型非麻醉性镇痛新药的重要先导化合物,本文对角蒿的化学成分、镇痛活性、作用机理和构效关系的研究作一综述。     

Monoclonal Antibody to a Bacterial Endonuclear Symbiont Holospora Cross Reacts with Proteins of Contractile Vacuole Radial Canals of Paramecium Species

ABSTRACT A monoclonal antibody (mAb) IR-2-1 was raised against a 67-kDa protein purified from the macronucleus-specific bacterial symbiont Holospora obtusa of Paramecium caudatum. The mAb was found to react with two bands (31 and 67-kDa) on gels of H. obtusa. Indirect immunofluorescence microscopy showed that these antigens were distributed inside the cells. However, unexpectedly, this mAb also cross reacted with the radial arms of the contractile vacuole in P. caudatum, P. tetraurelia, P. multimicronucleatum, P. jenningsi and P. bursaria as well as with their cytoplasm. Immunoelectron microscopy showed that the antigens were located on the decorated spongiome of the radial arms. In immunoblots, mAb IR-2-1 reacted with a band of 67 kDa in all Paramecium species examined. However, no band appeared in the immunoblot of isolated macronuclei of H. obtusa-free P. caudatum and no label was seen in the nuclear matrix of the macronucleus of air-dried P. caudatum. These results suggest that the 67-kDa antigen found in H. obtusa was not imported from the host macronucleus and the same antigen in the host contractile vacuoles and cytoplasm were not derived from the symbiont. These results also showed that an epitope on the decorated spongiome of the Paramecium species is shared by its bacterial symbiont. In contrast to the decorated tubule-specific mAb, DS-1, the antigens for IR-2-1 appeared to be loosely membrane bound as they were lost in paraformaldehyde fixed and acetone permeabilized Paramecium. Supplementary key words. Contractile vacuole complexes, Holospora obtusa, monoclonal antibody, Paramecium.     

Rice yield enhancement by elevated CO2 is reduced in cool weather

The projected increase of atmospheric CO₂ concentration ([CO₂]) is expected to increase rice yield, but little is known of the effects of [CO₂] at low temperature, which is the major constraint to growing rice in cool climates. We grew rice under two levels of [CO₂] (ambient and elevated by 200 μmol mol^?1) and two nitrogen (N) fertilization regimes in northern Japan in 2003 (cool weather) and 2004 (warm weather) in the field in a free‐air CO₂ enrichment (FACE) system. Elevated [CO₂] significantly increased grain yield in both years in both N regimes, but the magnitude of the increase differed between years: 6% in 2003 vs. 17% in 2004, with a significant interaction between [CO₂] and year. This difference resulted from responses of spikelet number and ripening percentage to elevated [CO₂]. Enhancement of dry matter production and N uptake at heading by elevated [CO₂] was smaller in 2003 than in 2004, although at maturity there was no difference between years. No significant interaction between N regime and [CO₂] was detected in yield and yield components. The results suggest that yield gain due to elevated [CO₂] can be reduced by low temperature.     

STUDIES ON CHLOROPHYLLASE OF CHLORELLA PROTOTHECOIDESI. ENZYMATIC PHYTYLATION OF METHYL CHLOROPHYLLIDE

1. The relation between chlorophyll content and the hydrolyticactivity of chlorophyllase in Chlorella protothecoides was examined.An increase in the activity was parallel to that in chlorophyllcontent during the development of green colouration, or greeningcourse, in the bleached cells. The activity sharply declinedand a parallel disappearance of chlorophyll was also found duringbleaching of the green cells.
2. A partially purified water-solublepreparation of chlorophyllasewas obtained by n-butanol treatmentand fractionation with coldacetone. It showed high activityand hydrolyzed 2 mg chlorophylla per hr per mg protein.
3. Forseparation and identification of the pigments concernedin thechlorophyllase reaction, a new solvent system of paperchromatographywas introduced.
4. When methyl chlorophyllide a and phytol wereincubated withthe enzyme, two products were formed. By comparisonwith theRf values of isolated pure substances, one was identifiedaschorophyll a and the other as chlorophyllide a. This enzymedid not catalyze the phytylation of free chlorophyllide a, butit had the ability to attach phytol to methyl chlorophyllidea. The final step in the biosynthesis of chlorophyll a is brieflydiscussed.

¹ Contribution No. 158 from the Department of Biology, Facultyof Science, Kyushu University. Supported in part by a grant-in-aidfor Fundamental Scientific Research from the Ministry of Education.     

Genetic Variation and Clonal Diversity of the Two Divergent Types of Clonal Populations of Leymus chinensis Tzvel on the Song Liao Steppe in the West of Northeastern China

The genetic variation and clonal diversity of two divergent types (grey-green and yellow-green) of clonal populations ofLeymus chinensis Tzvel at 14 loci were compared. Total gene diversity (HT) and the coefficient of genetic differentiation (GsT) were all higher for the yellow-green type (HT = 0.270; GsT = 0.186)than for the grey-green type (HT = 0.250; GsT = 0.157) of L. chinensis. Rare alleles usually occurred as heterozygotes rather than homozygotes and significant deviations from Hardy-Weinberg equilibrium were found only at a few loci. This indicated that these two types of populations were mainly out-crossing. Clonal diversity, evenness of clones, and mean clone size were not significantly different between the two types.We found that differences between the clone size and genetic variation of the yellow-green type of popula tions occurred with different climate and habitat population groups. However, for the grey-green type of populations, these genetic variations decreased under conditions of different climate and habitat popula tion groups.