CH4 emission with differences in atmospheric CO2 enrichment and rice cultivars in a Japanese paddy soil

A pot experiment was conducted to investigate CH₄ emissions from a sandy paddy soil as influenced by rice cultivars and atmospheric CO₂ elevation. The experiment with two CO₂ levels, 370 μL L⁻¹ (ambient) and 570 μL L⁻¹ (elevated), was performed in a climatron, located at the National Institute for Agro‐Environmental Sciences, Tsukuba, Japan. Four rice cultivars were tested in this experiment, including IR65598, IR72, Dular and Koshihikari. Tiller number, root length and grain yield were clearly larger under elevated CO₂ than under ambient CO₂. IR72 and Dular showed significantly higher tiller number, root length and grain yield than Koshihikari and IR65598. Average daily CH₄ fluxes under elevated CO₂ were significantly larger by 10.9–23.8% than those under ambient CO₂, and varied with the cultivars in the sequence Dular ≧ IR72>IR65598 ≧ Koshihikari. Dissolved organic C (DOC) content in the soil was obviously higher under elevated CO₂ than under ambient CO₂ and differed among the cultivars, in the sequence IR72>Dular>Koshihikari>IR65598. The differences in average daily CH₄ fluxes between CO₂ levels and among the cultivars were related to different root exudation as DOC content, root length and tiller number. This study indicated that Koshihikari should be a potential cultivar for mitigating CH₄ emission and simultaneously keeping stable grain yield, because this cultivar emitted lowest CH₄ emission and produced medium grain yield.     

Fine Structural Changes in the Acrosome Reaction of the Japanese Abalone, Haliotis disus

The spermatozoon of the Japanese abalone, Haliotis discus , and its structural changes during the acrosome reaction were observed by electron microscopy. The spermatozoon has a huge acrosome in the shape of a hanging bell or a forefinger with a deep fossa at the posterior end being filled with a bundle of microfilaments. The membranes of the acrosomal apex, the so-called trigger region, are structurally discernible from those of other acrosomal regions. Following the trigger region, a unique structure under the acrosomal membrane covers the surface of the acrosomal content in the form of a truncated cone.
The acrosome reaction occurs in the jelly layer very close to the egg envelope. First, the membranes at the apex of the acrosome are vesiculated, followed by the formation of a narrow gap between the outer acrosomal membrane and the acrosomal content. Next, the bundle of micro-filaments elongates, running through the center of the acrosome, reaching the trigger region and protruding out of the acrosomal top. Then release of the acrosomal content occurs in two steps, disclosing the "membrane undercoating structure" that comprises globular particles with a fuzzy material connecting them. This resembles the undercoat network found in erythrocytes.     

Evolution of epiphytes in Davalliaceae and related ferns

The evolution of epiphytes in Davalliaceae was investigated by field observations and molecular phylogenetic analyses. Field studies revealed that in Davalliaceae and related ferns, epiphytes in a broad sense are classified into climber, secondary hemi-epiphyte, and obligate epiphyte, based on combinations of the places (ground vs. tree) of inferred spore germination and sporophyte growth. Some species of Davalliaceae have multiple life forms, i.e. secondary hemi-epiphyte and obligate epiphyte, whereas others are obligate epiphytes. Phylogenetic trees obtained from rbcL and accD gene sequences supported that secondary hemi-epiphytic Oleandra is sister to the epiphytic Davalliaceae and polygrammoid ferns. Analyses of life form evolution based on the phylogenetic relationships suggested that obligate epiphytes of the Davalliaceae and polygrammoid ferns evolved from secondary hemi-epiphytes, or less likely from climbers. We hypothesized a scenario for the evolution of life forms in Davalliaceae and related groups that involves successive changes in rhizome habit, root function, and germination place. Rhizome dorsiventrality and scale morphology, shared by climbers, secondary hemi-epiphytes, and obligate epiphytes examined, may be other innovations for the ferns to have evolved into epiphytes.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 495–510.     

Preliminary characterization and biological reduction of putative biogenic iron oxides (BIOS) from the Tonga-Kermadec Arc, southwest Pacific Ocean

Sediment samples were obtained from areas of diffuse hydrothermal venting along the seabed in the Tonga sector of the Tonga‐Kermadec Arc, southwest Pacific Ocean. Sediments from Volcano 1 and Volcano 19 were analyzed by X‐ray diffraction (XRD) and found to be composed primarily of the iron oxyhydroxide mineral, two‐line ferrihydrite. XRD also suggested the possible presence of minor amounts of more ordered iron (hydr)oxides (including six‐line ferrihydrite, goethite/lepidocrocite and magnetite) in the biogenic iron oxides (BIOS) from Volcano 1; however, Mössbauer spectroscopy failed to detect any mineral phases more crystalline than two‐line ferrihydrite. The minerals were precipitated on the surfaces of abundant filamentous microbial structures. Morphologically, some of these structures were similar in appearance to the known iron‐oxidizing genus Mariprofundus spp., suggesting that the sediments are composed of biogenic iron oxides. At Volcano 19, an areally extensive, active vent field, the microbial cells appeared to be responsible for the formation of cohesive chimney‐like structures of iron oxyhydroxide, 2–3 m in height, whereas at Volcano 1, an older vent field, no chimney‐like structures were apparent. Iron reduction of the sediment material (i.e. BIOS) by Shewanella putrefaciens CN32 was measured, in vitro, as the ratio of [total Fe(II)]:[total Fe]. From this parameter, reduction rates were calculated for Volcano 1 BIOS (0.0521 day^?1), Volcano 19 BIOS (0.0473 day^?1), and hydrous ferric oxide, a synthetic two‐line ferrihydrite (0.0224 day^?1). Sediments from both BIOS sites were more easily reduced than synthetic ferrihydrite, which suggests that the decrease in effective surface area of the minerals within the sediments (due to the presence of the organic component) does not inhibit subsequent microbial reduction. These results indicate that natural, marine BIOS are easily reduced in the presence of dissimilatory iron‐reducing bacteria, and that the use of common synthetic iron minerals to model their reduction may lead to a significant underestimation of their biological reactivity.     

Biosynthesis of ethylene in sweet potato root tissue

The biosynthetic pathway of ethylene in freshly cut and blackrot-diseased tissues of sweet potato roots was investigated.Glucose-U-¹⁴C administration gave labeled ethylene in both freshand diseased tissues, but at the early stage of infection, therewas ethylene production which was not derived from the fed ¹⁴C-glucose.Acetate-1-¹⁴C and acetate-2-¹⁴C were equally incorporated intoethylene produced from fresh tissue, but acetate-2-¹⁴C was preferentiallyincorporated into ethylene from diseased tissue. Pyruvate-3-¹⁴Cwas more efficient as a precursor than was acetate or glucosein fresh tissue, while its efficiency was the same as that ofacetate in diseased tissue. Monofluoroacetate promoted pyruvate-3-¹⁴Cincorporation in fresh tissue but inhibited incorporation indiseased tissue. We concluded that the TCA cycle is involvedin the case of diseased tissue but not in fresh tissue; thus,showing different pathways for ethylene production in each tissue.In addition, in diseased tissue, ethylene is assumed to be producedfrom some cellular component(s), not easily synthesized fromglucose through fungus infection, but is degraded as soon asinfection commences. ¹This paper constitutes Part 85 of the Phytopathological Chemistryof Sweet Potato with Black Rot and Injury ²Present address: The Institute for Biochemical Regulation,Faculty of Agriculture, Nagoya University, Chikusa, Nagoya 464,Japan (Received April 20, 1970; )     

Increased night temperature reduces the stimulatory effect of elevated carbon dioxide concentration on methane emission from rice paddy soil

To determine how elevated night temperature interacts with carbon dioxide concentration ([CO₂]) to affect methane (CH₄) emission from rice paddy soil, we conducted a pot experiment using four controlled‐environment chambers and imposed a combination of two [CO₂] levels (ambient: 380 ppm; elevated: 680 ppm) and two night temperatures (22 and 32 °C). The day temperature was maintained at 32 °C. Rice (cv. IR72) plants were grown outside until the early‐reproductive growth stage and then transferred to the chambers. After onset of the treatment, day and night CH₄ fluxes were measured every week. The CH₄ fluxes changed significantly with the growth stage, with the largest fluxes occurring around the heading stage in all treatments. The total CH₄ emission during the treatment period was significantly increased by both elevated [CO₂] (P=0.03) and elevated night temperature (P<0.01). Elevated [CO₂] increased CH₄ emission by 3.5% and 32.2% under high and low night temperature conditions, respectively. Elevated [CO₂] increased the net dry weight of rice plants by 12.7% and 38.4% under high and low night temperature conditions, respectively. These results imply that increasing night temperature reduces the stimulatory effect of elevated [CO₂] on both CH₄ emission and rice growth. The CH₄ emission during the day was larger than at night even under the high‐night‐temperature treatment (i.e. a constant temperature all day). This difference became larger after the heading stage. We observed significant correlations between the night respiration and daily CH₄ flux (P<0.01). These results suggest that net plant photosynthesis contributes greatly to CH₄ emission and that increasing night temperature reduces the stimulatory effect of elevated [CO₂] on CH₄ emission from rice paddy soil.     

CYTOPLASMIC DYNEIN OF THE SEA URCHIN EGG I. PARTIAL PURIFICATION AND CHARACTERIZATION*

Cytoplasmic ATPase of sea urchin eggs was partially purified by ammonium sulfate fractionation, DEAE-cellulose chromatography, gel-filtration chromatography and sucrose density gradient centrifugation. The specific activity increased to 0.7 μmole/min/mg protein indicating 100 fold purification. The ATPase had a sedimentation constant of 12S and was highly specific for ATP. The enzyme fraction contained neither (Na, K)-ATPase, Ca-ATPase, oligomycin-sensitive ATPase, phosphatases, nor myosin. This cytoplasmic ATPase was inhibited by a low concentration of vanadate (V). Half-maximal inhibition was observed at a vanadate concentration of 1 μM at low ionic strength. The inhibition was almost totally reversed by addition of norepinephrine. The vanadate-sensitivity of cytoplasmic ATPase decreased with increasing KCl concentration. The activation by Mg²⁺ or Ca²⁺, and dependence of the activity on KCl concentration characteristic of dyneins from sea urchin sperm flagella and the embryonic cilia were observed with cytoplasmic ATPase. These results allowed the cytoplasmic ATPase to be classified as a dynein. In addition, this designation was reinforced by the fact that an oligomeric 23S form of cytoplasmic dynein was identified in the cytoplasm as well as in the isolated mitotic apparatus.     

SPERMIOGENESIS OF THE TELEOST,ORYZIAS LATIPES,WITH SPECIAL REFERENCE TO THE FORMATION OF FLAGELLAR MEMBRANE *

In the early stage of Oryzias spermiogenesis, an axonemal bud appears at the distal end of a centriole characterized by its electron dense accessories. When the axoneme begins to grow in the cytoplasm, small vesicles come to surround it. These vesicles are similar to those produced by the Golgi apparatus which lies close to the growing axoneme. At this stage, the spermatid cell membranes disappear, causing transformation of the mononuclear spermatids into a multinucleated syncytium. As each axoneme elongates in the syncytium, it is enveloped by a cylindrical array of vesicles which are most likely derived from the Golgi apparatus. Shortly after this stage, the syncytium is again partitioned by cell membranes, restoring the existence of mononuclear spermatids. The arrayed vesicles fuse with each other to form two concentric membranes surrounding the axoneme. The inner membrane becomes the flagellar membrane and the outer one, the membrane of a flagellar sheath. These observations lead to the conclusion that the formation of the flagellar membrane is due to the fusion of vesicles surrounding the axoneme which are derived from the Golgi apparatus. In the course of spermiogenesis, no indication of an acrosomal structure is observed.     

Microsatellite markers isolated from polyploid wood‐sorrel Oxalis alpina (Oxalidaceae)

Twelve polymorphic microsatellite loci were isolated from polyploid alpine wood‐sorrel, Oxalis alpina (Oxalidaceae), and optimized for future studies of its breeding system. The loci were screened for variability among 72 individuals from Pinos Altos, New Mexico. The primers amplified loci with allele number ranging from two to 17 per locus and with estimates of Nei's genetic diversity varying from 0.10 to 0.99. These primers provide an opportunity to use polymorphic DNA markers to study the causes of breeding system variability in this species.