Microbial community indigenous to the earthworm Eisenia foetida     

Koki Toyota  Makoto Kimura 《Biology and Fertility of Soils》2000,31(3-4):187-190

 Microbial populations of the earthworm Eisenia foetida, their casts and farmyard manure (FYM) in which E. foetida had lived were enumerated with the dilution plate method using several media. The microbial community of earthworms appeared to be similar to that of the FYM in which they had lived, while that of earthworms starved in distilled water for 24 h greatly differed from that of the FYM. The community of the starved earthworms consisted exclusively (more than 90%) of fast growers, which were defined as those that formed their colonies within 2 days, unlike that of the FYM (10–30%). About 30 isolates were randomly chosen and some physiological properties were examined. The community of starved earthworms consisted exclusively of Gram-negative, oxidase-positive, fermentative bacteria, whereas bacteria from the FYM were much more diverse and there were no fermentative bacteria in the FYM. The predominant bacteria species of the starved earthworms were identified as Aeromonas hydrophila and considered to be indigenous to the earthworm E. foetida. Received: 18 June 1999  相似文献   

Retention of a European pear aroma model mixture using different types of saccharides     

Tobitsuka K  Miura M  Kobayashi S 《Journal of agricultural and food chemistry》2006,54(14):5069-5076

Eight types of microcapsules of European pear (La France) aroma model mixture were prepared, and their retained aroma components and sample microstructures (both surface and cross-section) were compared. The La France pear aroma model mixture was prepared by the mixing of hexanal and five kinds of esters. alpha-Cyclodextrin (alpha-CD), gum arabic (GA), soybean soluble polysaccharide (SSPS), and highly branched cyclic dextrin (HBCD) were used as carrier solids, and spray drying and freeze drying comprised the drying methods. The mean particle size of the microcapsules ranged from 8.34 microm for the microcapsules with alpha-CD to 9.67 microm for those with SSPS. The total aroma contents were different depending upon the microencapsulation systems (1.35 g/100 g of microcapsules for the spray-dried microcapsules with HBCD to 14.1 g/100 g of microcapsules for the freeze-dried microcapsules with GA). The microcapsules with alpha-CD and GA were stable against heat treatment (40, 80, or 120 degrees C for 60 min) under nitrogen gas flow.  相似文献   

Hyperproduction and application of alpha-agarase to enzymatic enhancement of antioxidant activity of porphyran     

Hatada Y  Ohta Y  Horikoshi K 《Journal of agricultural and food chemistry》2006,54(26):9895-9900

The nucleotide sequence of the gene for the alpha-agarase, AgaA33, from Thalassomonas sp. strain JAMB-A33 was determined. The open reading frame for AgaA33 was revealed to encode 1463 amino acid residues. We succeeded in extracellular production of recombinant -agarase (AgaA33) efficiently using Bacillus subtilis as a host. This is the first report of recombinant production of -agarase. Furthermore, we demonstrated that hydrolysis of alpha-1,3 linkages in porphyran, a sulfated polysaccharide from marine red algae, by alpha-agarase is an important step for improvement of its antioxidant activity with regard to free-radical-scavenging capacity and superoxide radical anion scavenging activity, whereas the hydrolysis of beta-1,4 linkages in porphyran by beta-agarase did not increase on the antioxidant activity markedly.  相似文献   

Soil management: The key factors for higher productivity in the fields utilizing the system of rice intensification (SRI) in the central highland of Madagascar   总被引：1，自引：0，他引：1  

Yasuhiro Tsujimoto  Takeshi Horie  Hamon Randriamihary  Tatsuhiko Shiraiwa  Koki Homma   《Agricultural Systems》2009,100(1-3):61-71

The system of rice intensification (SRI) developed in Madagascar in the 1980s has been promoted as an integrated crop and resource management approach to rice-cultivation, especially for resource-limited smallholder farms. While advocates have claimed that SRI could boost rice yields with less external input, many criticisms have challenged its effectiveness regarding yields and applicability to larger-scale rice farming systems. In this study, we conducted a field survey and on-farm experiments to assess rice yield performance and key management practices on a few of the early SRI-practicing smallholder farms in the central highland of Madagascar.Rice grain yields at the survey fields were 9.9 t ha⁻¹ maximum without using mineral fertilizer. Deep plowing to the depth of 25–30 cm as well as SRI practices have been conducted continuously since the early 1990s. In addition, an effective drainage system facilitated intensive water management at these high-yielding fields. On-farm experiments demonstrated some yield increases with no interaction for the examined SRI practices, though the effects were not great enough to explain the high yields at these fields. The soils of these high-yielding fields contained relatively large amounts of soil organic carbon (SOC) from the surface to the deep soil layers, and the soil mineralizable nitrogen was closely correlated with rice grain yields.The results indicated that the high yields at the fields of those who were early to adopt SRI were mainly due to the soil fertility associated with great nitrogen-supplying ability, rather than ‘synergetic effects’ of the SRI components. This high N-supplying ability of the soil and accumulated SOC from surface to deep soil layers were attributable to the long-term combined practices of extensive organic applications and deep plowing. Soil hydrology could be another key factor stimulating high rates of soil N-mineralization.These management practices were, however, only applied to the limited numbers of fields within less than 1.0 ha of total landholdings of these farmers due to the great demand in labor and organic resources and the difficulty in controlling irrigation water. Intensive weeding and widely spaced transplanting of young seedlings were also performed in the fields with irrigation and drainage systems sufficient to avoid yield losses from flooding and drought. Although extensive and long-term systematic research is further required to fully assess the benefits of this sort of intensive management as opposed to conventional methods, the preferential allocation of intensive management by the successful SRI-adopters might be the implication of its location-specificity and difficulty in scaling up even within the resource-limited smallholder farms.  相似文献   

Basin-scale distribution pattern and biomass estimation of Japanese anchovy Engraulis japonicus in the western North Pacific     

Hiroto Murase  Atsushi Kawabata  Hiroshi Kubota  Masayasu Nakagami  Kazuo Amakasu  Koki Abe  Kazushi Miyashita  Yoshioki Oozeki 《Fisheries Science》2012,78(4):761-773

The distribution pattern and biomass of the Japanese anchovy Engraulis japonicus in the offshore region of the western North Pacific (north of 35°N and west of 170°E) were studied using a quantitative echosounder. This is the first attempt at such a study in this region. Data were collected in summer from 2004 to 2007. The biomass was estimated using data collected at 38?kHz. Species compositions in the backscatterings from pelagic fish were assigned based on the results of trawl hauls taking account of sea surface temperature (SST). Japanese anchovy tended to be high density to the west of 153°E and were distributed in an SST range of 9?C24?°C. Although the temporal and spatial coverage of the survey differed each year, at least 1.5?C3.4 million tons of Japanese anchovy were present in the survey area between 2004 and 2007. To take account of the spatial coverage of the survey each year, the most reliable biomass estimate for this region in the time period was 3.4 million tons (coefficient of variation?0.22).  相似文献   

Abstracts of Nippon Dojohiryogaku Zasshi     

Erika Sato  Yuko Suga  Chihiro Kisaki  Koki Toyota  Kazuto Miyake  Atsushi Takada 《Soil Science and Plant Nutrition》2013,59(2):213-222

Abstract

The humus composition was analyzed and the humic acid characterized by UV and visible absorption spectroscopy in order to investigate the rotting and maturing process of city refuse compost according to the method of Kumada et al. During the composting process, the following findings were obtained: (1) the HT value was almost constant, but the HE/HT ratio varied somewhat, (2) HA increased with decrease in FA, and the PQ value so increased clearly, (3) the shoulder-like absorption at a wavelength near 270 nm weakened, and (4) the RF value of humic acid increased, whereas the Δ log K value seldom varied.

The IR spectrum of humic acid gradually changed as follows: (1) the absorption band in the 1700-1600 cm^-1 region and in the 1550-1500 cm^-1 region increased slightly, (2) the band in the 1100-1000 cm^-1 region decreased, and (3) the bands at 835 and 710 cm^-1 com pletely disappeared. On the whole, the shape of the IR spectrum of the city refuse compost became featureless. These changes were probably due to the oxidation which occurred in the composting process.  相似文献   

Suppression of Ralstonia solanacearum in soil following colonization by other strains of R. solanacearum     

Koki Toyota  Makoto Kimura 《Soil Science and Plant Nutrition》2013,59(2):449-459

The effect of prior colonization of a sterile loam soil and a sterile clay loam soil by individual soil bacteria on the subsequent growth of a bacterial wilt pathogen Ralstonia solanacearum YU1Rif43 (tRNA type III: Seal et al. 1992: Appl. Environ. Microbiol., 58, 3759–3761) was investigated. Various strains, belonging to the same type, the same species, the same genus, Gram-negative, Grampositive, or fungi, were used. The degree of suppression of the growth of R. solanacearum YU1Rif43 was markedly different depending on the species that had previously colonized the soil, hereafter referred to as priorcolonists. All the strains belonging to R. solanacearum type III suppressed the growth of R. solanacearum YU1Rif43 markedly, while strains of R. solanacearum type I and type II showed a moderate suppressive effect on R. solanacearum YU1Rif43. The suppressive effect of the strains belonging to species other than R. solanacearum, including fungal strains, was relatively limited, or some strains did not show any suppressive effect. The production of bacteriocin did not appear to be related to the strong suppressive effect of the R. solanacearum type III strains. Possible mechanisms for the suppressive effect of priorcolonists on R. solanacearum YU1Rif43 are discussed in relation to nutrients and physical sites in soil available for growth.  相似文献   

An in vitro screening assay to discover novel inhibitors of 4-coumarate:CoA ligase     

Yun MS  Chen W  Deng F  Kiyokawa T  Mametsuka K  Yogo Y 《Pest management science》2006,62(11):1065-1071

4-Coumarate:CoA ligase (4CL, EC 6.2.1.12) exists only in plants and plays an important role in the phenylpropanoid pathway. Identification of inhibitors targeting 4CL provides a novel approach for developing effective plant growth inhibitors (PGIs). The full-length gene of tobacco 4CL (Nt4CL1) was cloned and expressed in Escherichia coli Cast & Chalm. The recombinant 4CL protein was extracted and purified by several purification steps including gel-filtration and anion-exchange chromatography. 4CL activity assay was miniaturized and optimized using a 96-well microplate and a reader. Among 28 existing herbicides, propanil and swep strongly inhibited in vitro 4CL enzyme activity, and they were selected for further studies. The process of this assay can be developed into a high-throughput screening system of PGI targeting 4CL in the phenylpropanoid pathway.  相似文献   

Introduction of a point mutation in the KRAS gene of in vitro fertilized porcine zygotes via electroporation of the CRISPR/Cas9 system with single-stranded oligodeoxynucleotides     

Manita Wittayarat  Maki Hirata  Zhao Namula  Yoko Sato  Nhien T. Nguyen  Quynh A. Le  Qingyi Lin  Koki Takebayashi  Fuminori Tanihara  Takeshige Otoi 《Animal Science Journal》2021,92(1):e13534

This study aimed to investigate the efficiency of KRAS gene editing via CRISPR/Cas9 delivery by electroporation and analyzed the effects of the non-homologous end-joining pathway inhibitor Scr7 and single-stranded oligodeoxynucleotide (ssODN) homology arm length on introducing a point mutation in KRAS. Various concentrations (0–2 µM) of Scr7 were evaluated; all concentrations of Scr7 including 0 µM resulted in the generation of blastocysts with a point mutation and the wild-type sequence or indels. No significant differences in the blastocyst formation rates of electroporated zygotes were observed among ssODN homology arm lengths, irrespective of the gRNA (gRNA1 and gRNA2). The proportion of blastocysts carrying a point mutation with or without the wild-type sequence and indels was significantly higher in the ssODN20 group (i.e., the group with a ssODN homology arm of 20 bp) than in the ssODN60 group (gRNA1: 25.7% vs. 5.4% and gRNA2: 45.5% vs. 5.9%, p < .05). In conclusion, the CRISPR/Cas9 delivery with ssODN via electroporation is feasible for the generation of point mutations in porcine embryos. Further studies are required to improve the efficiency and accuracy of the homology-directed repair.  相似文献   

Suppression of nitrous oxide production by the herbicides glyphosate and propanil in soils supplied with organic matter     

Khin Moe KYAW  Koki TOYOTA 《Soil Science and Plant Nutrition》2007,53(4):441-447

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