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1.
Spatially distributed morphological characteristics of macropores in forest soils of Hitachi Ohta Experimental Watershed, Japan 总被引:1,自引:0,他引:1
Shoji Noguchi Yoshio Tsuboyama Roy C. Sidle Ikuhiro Hosoda 《Journal of Forest Research》1997,2(4):207-215
Morphological characteristics of macropores in forest soil profiles were investigated at Hitachi Ohta Experimental Watershed
in Japan. Nine individual profiles at different locations (various spatial scales in a catchment) and twenty profiles at one
site (a small spatial scale) were excavated to the bedrock to investigate density, origin, diameter, direction, and gradient
of macropores. Macropore densities in a soil profile ranged from 3.5 to 29.1 per m and from 5.4 to 75.1 per m2, respectively. Subsurface erosion, root channels, and interactions between subsurface erosion and root channels accounted
for 36.9, 36.5, and 19.0%, of the described macropores. The mean macropore diameter in organic-rich soil layer (17–20 mm)
was larger than in the B horizon (11–14 mm) at both spatial scales. The dominant gradients of all macropores in the organic-rich
soil layer and B horizon were at negative oblique angles. Approximately 90% of the macropores in the organic-rich soil layer
and approximately 80% of the macropores in the B horizon fell within the range between −50 and 50 degree planar direction.
Subsurface flow and root systems are believed to play important roles in determining the morphological characteristics of
macropores. These characteristics appear to have variable influences in different soil horizons rather than at different spatial
scales.
A part of this paper was presented at the 103th (1992) and 105th (1994) Annual Meetings of Japanese Forestry Society. 相似文献
2.
Summary Mitochondrial DNA (mtDNA) diversity has been determined in apple landraces and cultivars, based upon restriction fragment length polymorphisms (RFLPs) for several mitochondrial genes. Our analysis includes three cultivars, Golden Delicious, McIntosh and Delicious, which represent the various patterns of mtDNA polymorphisms previously described (Ishikawa et al., 1992). A total of five RFLPs were detected, allowing classification of the apple genotypes into four cytoplasmic groups: GroupI, Golden Delicious-type; GroupII, McIntosh-type; GroupIII, Delicious-type; and Group IV, Dolgo Crab-type. European landraces and cultivars were assigned to Groups I, II, and III, while chinese crab apples were placed in either Group III or IV. 相似文献
3.
Three apple (Malus×domestica) cultivars and 11 Malus accessions have been investigated by the probe hybridization method on their mitochondrial DNA (mtDNA). The gene probes used were: coxI, coxII, atpA, atp6, and atp9. Our results revealed enough variation to characterize ten mtDNA haplotypes among the Malus genotypes examined. The taxonomic and phylogenetic implications of mtDNA polymorphism are also discussed. 相似文献
4.
Yoshiya Shimamoto Hirofumi Fukushi Jun Abe Akira Kanazawa Junyi Gai Zhong Gao Donghe Xu 《Genetic Resources and Crop Evolution》1998,45(5):433-439
RFLPs of chloroplast (cp) and mitochondrial (mt) DNA have been used to characterize the cytoplasmic genome of wild soybean, Glycine soja, growing in China. We have found from the RFLPs of that the cytoplasmic genomes of most Chinese wild soybeans have a combination of cpIII with mt-a or a combination of cpII with mt-b accompanied by mtIV or mtV according to our classification. CpII was not observed in combination with mt-a and cpIII was not observed in combination with mt-b. The regional distribution of these two types showed clines with opposite directions. The Yangtze River Valley had the greatest diversity in each of cp and two mt profiles detected in this study and the cytoplasmic genome combining these three profiles showed the highest degree of polymorphism in this region. The Yangtze River Valley may be a center of cytoplasmic diversity of wild soybean and may contain various genetic resources of soybean. 相似文献
5.
A large numbers of samples of wild soybean accessions and cultivated soybean landraces from various areas in China were analyzed by isozyrme, cytoplasmic DNA RFLP and nuclear DNA RAPD markers in order to reveal their genetic diversity. Greater comprehensive genetic diversity was detected in wild soybean than in cultivated soybean. The genetic plentifulness and the genetic dispersion of wild soybean were 180 (95. 2%) and 0. 2891 while those of cultivated soybean were 154(81.5%) and 0. 2091,respectively. On the most loci, especially on isozyme loci Idh1, Aph, Idh2,and Dia, cytoplasmic DNA RFLP loci cp Ⅰ , cp Ⅲ, mt Ⅳ a and mt Ⅳ b, and nuclear RAPD loci OPAP4-8, OPAP5-1, OPAP9-8 and OPAP20-8, the wild soybeans djffered remarkably from the cultivated ones in allele frequency. These markers could be used in further study on the evolution and origin of the cultivated soybean. 相似文献
6.
To characterize the mechanism of the reaction of lignin with aqueous acetic acid (AW) containing a small amount of H2SO4, guaiacylglycerol--guaiacyl ether (GOG), and guaiacylglycerol--syringol ether (GOS) were refluxed in 90% AW with 0.28% H2SO4 for 0–120 min. Reaction products and their silylated derivatives were characterized by analytical methods such as gas chromatography-mass spectrometry and nuclear magnetic resonance. When the model compounds were allowed to react at boiling temperature for 0 min (heat-up time 30 min), most of their primary alcohol groups and some of their secondary alcohol groups were acetylated, but their phenolic groups were not. About 90% of GOG was degraded, polymerized, or both during boiling for at least 15 min, yielding guaiacol and isocoumaran compounds (GOG-e and GOG-f) in addition to homovanillin (II) as guaiacylvinyl alcohol (I) and other minor products. GOS yielded syringol, homovanillin (II), and a novel compound (V) together with unknown products but not the corresponding isocoumaran compounds. 相似文献
7.
8.
Maiko Sato Ashraf M Ahmed Ayako Noda Hitoshi Watanabe Yukio Fukumoto Tadashi Shimamoto 《Acta veterinaria Scandinavica》2009,51(1):46
Imported animals, especially those from developing countries, may constitute a potential hazard to native animals and to public health. In this study, a new flock of lesser flamingos imported from Tanzania to Hiroshima Zoological Park were screened for multidrug-resistant Gram-negative bacteria, integrons and antimicrobial resistance genes. Thirty-seven Gram-negative bacterial isolates were obtained from the flamingos. Seven isolates (18.9%) showed multidrug resistance phenotypes, the most common being against: ampicillin, streptomycin, tetracycline, trimethoprim/sulfamethoxazole and nalidixic acid. Molecular analyses identified class 1 and class 2 integrons, β-lactamase-encoding genes, blaTEM-1 and blaCTX-M-2 and the plasmid-mediated quinolone resistance genes, qnrS and qnrB. This study highlights the role of animal importation in the dissemination of multidrug-resistant bacteria, integrons and antimicrobial resistance genes from one country to another. 相似文献
9.
The extinction of genetic resources of Asian wild rice, Oryza rufipogon Griff.: A case study in Thailand 总被引:5,自引:0,他引:5
Masahiro Akimoto Yoshiya Shimamoto Hiroko Morishima 《Genetic Resources and Crop Evolution》1999,46(4):419-425
Natural populations of wild rice, Oryza rufipogon Griff., are now threatened with the disturbance of their natural habitats by various human activities. To obtain basic information on genetic erosion or loss of genetic diversity in wild rice, we investigated how environmental changes of habitat affected the genetic structure of its natural population at a study site in the central plain of Thailand. During 10 years from 1985 to 1994, the wild-rice population at this site was seriously destroyed and fragmented. Using two sets of seed sample collected in 1985 and 1994 from the same population, allozyme variability at 17 loci of 11 enzymes were examined. Isozyme genotypes of mother plants of seed samples were estimated by the segregation in each progeny, and we calculated genetic parameters for the population. Gene diversity severely decreased in the 1994 sample compared with the 1985 sample. It is supposed that declining and fragmentation of the wild rice population, which happened during the 10 years, caused loss of genetic variability and forced the habitually outbreeding plants to inbreed, accelerating a reduction in gene variability. Pgi1-1 allele which was common in Indica rice cultivars of this region was found in the wild rice plants growing at the side of rice fields. Probably, introgression has occurred between wild and cultivated rice plants, and consequently the intrinsic nature of wild rice was gradually blurred by cultivar genes. We must realize that the genetic erosion of wild rice is rapidly proceeding and that an action for their conservation in natural environment, so called in situ conservation, is urgently needed. 相似文献
10.
中国野生大豆与栽培大豆等位酶、RFLP和RAPD标记的遗传多样性与演化趋势分析 总被引:6,自引:1,他引:5
选用来自全国各地野生大豆和栽培大豆地方品种中有代表性的材料,分析其在等位酶、细胞器DNA RFLP和细胞核DNA RAPD标记位点上的群体遗传表现。结果表明:野生大豆在上述标记位点上的综合遗传多样性水平高于栽培大豆,二者的综合遗传丰富度和遗传离散度分别为180(95.2%)和154(81.5%)及0.2891和0.2091。野生大豆与栽培大豆群体在所分析的大多数位点上等位基因的分布频率差异明显,其中差异较大的标记位点有Idh1、Aph、Idh2和Dia(等位酶);cpⅠ、cpⅢ、mtⅣa和mtⅣb(细胞器DNA RFLP);OPAP4-8,OPAP5-1,OPAP9-8和OPAP20-8(细胞核DNA RAPD)。这些标记位点可作为进化的标记性状,以研究大豆的起源和演化问题。 相似文献