Comparative studies on the photosynthesis of higher plants

1) CO₂ compensation points of the plants tested correlate well with the leaf anatomy. Low CO₂ compensation plants had well-developed VBS containing large and specialized chloroplasts but no plant with a high CO₂ compensation point possessed chloroplasts in the VBS.

2) CO₂ Compensation Points Closely Correlated With The Major Carboxylation Pathway In Photosynthesis. Low Compensation Plants Fixed CO₂ Via The C-4 Pathway (C-4 Plants) While High Compensation Plants Carried Out CO₂ Fixation By The Calvin Cycle (C-3 Plants).

3) Close correlations could be established for the CO₂ compensation point, the major carboxylation pathway, and glycolate oxidase activity. Glycolate oxidase activity was much higher in C-3 plants than in C-4 plants. On the other hand, dark respiration in C-4 plants was higher than that in C-3 plants.

4) TCA cycle activity in detached leaves was not inhibited to any large extent by illumination.

In C-3 plants, the release of ¹⁴CO₂ from alanine-1-¹⁴C increased with an increase in the ambient O₂ concentration; whereas, radioactivity in the sugar fraction was quite small at all O₂ concentrations. In C-4 plants the release of ¹⁴CO₂ was little affected by the ambient O₂ concentration while sugar formation was stimulated at high O₂ concentrations. This indicates that in C-3 plants CO₂ fixation is blocked at a high O₂ concentration, therefore, internal ¹⁴CO₂ is released from the leaf without being refixed, but in C-4 plants internal ¹⁴CO₂ can be efficiently refixed and metabolized to sugar by a combination of active PEP carboxylase and the ‘Kranz type’ of leaf anatomy.     

西藏青稞秸秆与多年生黑麦草混合青贮发酵品质的研究

本研究旨在将青稞秸秆与黑麦草以不同比例混合青贮,评价其发酵品质,筛选出适宜的混合比例。试验设青稞秸秆单独青贮(对照组)、80%青稞秸秆+20%多年生黑麦草混贮(L组)、60%青稞秸秆+40%多年生黑麦草混贮(M组)及40%青稞秸秆+60%多年生黑麦草混贮(H组)4个处理。青贮后第7,14和30天后打开青贮窖,测定青贮饲料发酵品质。结果表明,青稞秸秆与黑麦草混合青贮显著(P<0.05)提高了乳酸和水溶性碳水化合物含量,显著(P<0.05)降低了pH值和干物质含量,M和H组在乳酸产生的同时乙酸含量显著(P<0.05)提高,混贮组氨态氮/总氮略低于对照组(P>0.05),各组均显示较低的丙酸和丁酸含量。从秸秆利用最大化的角度出发,建议以40%黑麦草混合青贮较为适宜。     

Three‐dimensional CT observation of position and movability of the scapula in the horse using carcasses of Falabella

The three‐dimensionally real position and movement of the scapula in the lateral side of the ribcage could not be clarified in the horse, since the body size of the horse is too large to apply the CT scanning and image analysis methods. In this study, therefore, we examined the position and the movability of scapula using a carcass of the Falabella which is one of the smallest breeds of the horse. The whole skeletal system in thoracic part of the Falabella could be three‐dimensionally observed by CT scanning method. The three‐dimensional images show that the scapula cranially slides and the ventral part of the scapula dorso‐cranially rotates, when the shoulder joint moves to the most cranial position as simulation. The three‐dimensional rotation angle was approximately 10 degrees. As a result of comparative osteology of the scapula between Falabella and the large draft horse, the infraspinous fossa was caudally enlarged in the larger draft horse, whereas the Falabella had narrower infraspinous fossa. We suggest that it may be due to the adaptational morphological change in the scapula bearing various body weights among breeds. The three‐dimensional CT image analysis and the simulation in carcass contribute to the analysis of the bone movements of the horse during walking and running locomotion as well as the motion analysis from external functional‐morphological data.     

添加青稞酒糟对西藏地区青稞秸秆和高羊茅混合青贮发酵品质的影响

 ：为评价添加不同水平青稞酒糟对青稞秸秆与高羊茅（４∶６）混合青贮发酵品质的影响,试验设对照组（Ｃｏｎｔｒｏｌ）和３个添加水平（１０％,２０％和３０％）的青稞酒糟处理组,青贮后第７,１４和３０天后打开青贮窖,测定青贮饲料发酵品质。结果表明,添加青稞酒糟可以抑制青贮早期好氧性微生物的活性,促进乳酸发酵,使ｐＨ 值快速下降,青贮饲料快速进入稳定阶段。青贮３０ｄ后,与对照组相比酒糟处理显著降低（P＜０．０５）了青贮饲料的ｐＨ 值,提高了乳酸和水溶性碳水化合物含量,降低了（P＜０．０５）氨态氮／总氮及丙酸和丁酸含量。综合考虑,添加２０％ 酒糟效果更佳。     

Identification and primary structures of eel type I collagen proα1, proα2 and proα3

Many bony fish type I collagens have a characteristic third chain designated as α3(I). However, much less is known about the primary structure and distinction of the proα(I) chains. Their cDNAs were cloned by RT-PCR from the muscle tissue of Japanese eel, Anguilla japonica. Three cDNAs coding for the triple-helical domain of fibrillar collagen were identified as proα1(I), proα2(I) and proα3(I) chains by sequencing selected tryptic peptides isolated from eel type I collagen subunit chains, α1(I), α2(I) and α3(I). Eel proα3(I) had high amino acid sequence identity (81 %) to its proα1(I). The distribution of seven Cys residues in the C-propeptide of proα3(I) was identical to that of proα1(I). There was a third Cys residue at the 1,268th position from the N-terminus in proα1(I), though a supposed Cys residue at the 1,264th position in proα3(I) was replaced by a Ser residue. Similar replacement has been observed in the proα3(I) chains of trout and zebrafish. These combined results suggest that replacement of the Cys residue allows for the identification of fish collagen proα(I) previously not identified as proα3(I).     

Exotic hard clam in Tokyo Bay identified as Mercenaria mercenaria by genetic analysis

ABSTRACT:   An exotic hard clam has been observed in Tokyo Bay since the mid-1990s, which has been morphologically identified as Mercenaria mercenaria . The authors have determined 444-bp partial nucleotide sequences of mitochondrial DNA (mtDNA) 16S rRNA gene of 31 hard clam individuals collected in three locations of Tokyo Bay. Phylogenetic analysis indicated all individuals to be M. mercenaria . Two shell interior colorations (white or purple) were observed, but no relationships between the colorations and mtDNA haplotypes were detected. Frequency of clam individuals having white or purple shell significantly differed among locations, which was accompanied by heterogeneous amounts of acid-volatile sulfides and organic matter and mud ratio.     

Suppression of conidial germination and appressorial formation by silicate treatment in powdery mildew of strawberry

The mode of action of soluble silicon against strawberry powdery mildew (Sphaerotheca aphanis var. aphanis) was investigated in four experiments. First, silicon-treated leaves from plants grown with silicate (Si+) and control leaves were excised, inoculated with conidia, and subsequent germination and formation of appressoria in a petri dish was assessed after 24 h. The germination rate was 49.7% on Si+ leaves, and was 67.2% on control leaves (t-test, P < 0.01). Second, we soaked cellulose membranes in various solvents and then placed the membranes on 4% water agar, dusted the membranes with conidia, and examined after 12 h. No difference was apparent between any treatment and the control (distilled water). Third, strawberries growing hydroponically with additional silicon in the medium were inoculated with conidia, and leaves were observed with a scanning electron microscope 1–2 days after inoculation. Germ tubes and secondary hyphae were shorter and had fewer branches on Si+ leaves than on the control. Moreover, penetration appeared to be inhibited. Fourth, the cuticle was separated from leaves from plants grown as in the third experiment, placed on water agar, and dusted with conidia. Germination of conidia, observed with a light microscope, on Si+ leaves was suppressed markedly to 40%–60% of that of the control. These results suggested that soluble silicon induced physiological changes in the cuticle layer after absorption by the plant. In addition, soluble silicate reduced germination of conidia, formation of appressoria, and possibly the penetration of powdery mildew.     

Evaluation of quality indexes of bending performance and hardness for hardwoods

The mechanical properties of 613 small clear specimens of 35 species (11 ring-porous hardwoods, 19 diffuse-porous hardwoods, and 5 softwoods) were evaluated. The aim of the study was to examine indexes of wood quality that are easy to measure and that exhibit a high correlation with bending performance and hardness that are essential properties of hardwood products. The modulus of rigidity, dynamic modulus of elasticity, bending properties (modulus of elasticity, modulus of rupture, stress at the proportional limit, absorbed energy, Tetmajer’s modulus), dynamic energy absorption by an impact bending test, compressive strength parallel to the grain, shear strength, partial bearing strength, and Brinell’s hardness were measured. A high correlation was found between dynamic modulus of elasticity and static modulus of elasticity. Bending stress at the proportional limit was found to be approximately equivalent to the compressive strength parallel to the grain. Static energy absorption correlated with dynamic energy absorption. Tetmajer’s modulus was found to be closely related to the ratio of the initial stiffness within the elastic range to the secant modulus at the maximum load. A high correlation was observed between Brinell’s hardness and partial bearing strength. The difference in the regression coefficients obtained for these correlations between the species groups was small. Part of this study was presented at the All Division 5 Conference of IUFRO, Taipei, October 2007     

Molecular typing of Japanese strains of Ralstonia solanacearum in relation to the ability to induce a hypersensitive reaction in tobacco

The genetic diversity of 120 Ralstonia solanacearum strains isolated from a variety of host plants across Japan was assessed on the basis of hypersensitive response (HR) in tobacco leaves and phylogenetic analyses of endoglucanase gene egl, hrpB, and gyrB. Phylogenetic analysis of egl revealed that only three strains belonged to phylotype IV, and 117 strains belonged to phylotype I. Partial sequences of HrpB were identical among phylotype I strains except for one strain. Analyses using the partial nucleotide sequences of the gyrB and egl gene fragments grouped phylotype I strains into 11 gyrB and 8 egl types, respectively, whereas analyses using the partial amino acid sequences of GyrB and Egl grouped phylotype I strains into 4 GyrB and 5 Egl types, respectively. Using multilocus sequence typing of GyrB and Egl, we identified 10 unique sequence types within the Japanese phylotype I strains. Strains belonging to the GyrB42 or GyrB66 type caused wilt in tobacco, and strains belonging to GyrB2 or GyrB9 type elicited HR, demonstrating that HR induction in tobacco is genetically differentiated in the Japanese strains of R. solanacearum.