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11.
Vegetation dynamics in the coastal area of the Seto Inland Sea region in Japan, where wild fires occur frequently, were described
using a stationary Markov model. In this region, vegetation types ofMiscanthus-Pleioblastus grassland,Lespedeza-Mallotus scrub,Pinus-Rhododendron forest andCrassocephalum-Erechtites community have been identified, and these show cyclic succession under the influence of fires.
The model uses parameters determining fire frequency and rate of successional change to analyze the effect of variation in
these parameters on the areal ratio of each vegetation type at equilibrium and on the time taken for one vegetation type to
succeed another (elapsed successional time). The effect of fire frequency differs between hypothetical habitats with high
and low productivity. A policy for vegetation management in areas of high and low productivity is proposed. The advantages
and limitations of applying Markov models to studies of vegetation succession are also discussed. 相似文献
12.
Determination of base composition of DNA by high performance liquid chromatography of its nuclease P1 hydrolysate 总被引:1,自引:0,他引:1
The base composition of DNA was directly determined by high performance liquid chromatography (HPLC) of its nuclease P1 hydrolysate. This method can satisfactorily be employed even if the sample of DNA contains RNA or the amount of the sample is very small. 相似文献
13.
Identification of a single nucleotide change in a mutant gene for hypoxanthine-guanine phosphoribosyltransferase (HPRTAnn Arbor) 总被引:1,自引:1,他引:0
Shin Fujimori Yuji Hidaka Beverly L. Davidson Thomas D. Palella William N. Kelley 《Human genetics》1988,79(1):39-43
Summary HPRTAnn Arbor is a variant of hypoxanthine (guanine) phosphoribosyl-transferase (HPRT: EC 2.4.2.8), which was identified in two brothers with hyperuricemia and nephrolithiasis. In previous studies, this mutant enzyme was characterized by an increased Km for both substrates, a normal Vmax, a decreased intracellular concentration of enzyme protein, a normal subunit molecular weight and an acidic isoelectric point under native isoelectric focusing conditions. We have cloned a full-length cDNA for HPRTAnn Arbor and determined its complete nucleotide sequence. A single nucleotide change (TG) at nucleotide position 396 has been identified. This transversion predicts an amino acid substitution from isoleucine (ATT) to methionine (ATG) in codon 132, which is located within the putative 5-phosphoribosyl-1-pyrophosphate (PRPP)-binding site of HPRT. 相似文献
14.
Yoshiaki Fukuda Kohzoh Imai Kenju Miura Masashi Matsui Toshihiro Nakanishi Hiroshi Nakazato Johji Masukawa Toshiyuki Higashide Yuji Hinoda Teruhisa Noguchi Akira Yachi 《Cancer immunology, immunotherapy : CII》1988,27(1):26-32
Summary There have been few reports stating that monoclonal antibody alone inhibits human solid tumor growth in vivo. The present study demonstrated that monoclonal antibody S1 (IgG2a), which recognized the antigenic determinant of the carbohydrate moiety, showed antibody-dependent cell (or macrophage)-mediated cytotoxicity (ADCC or ADMC) in conjunction with murine splenocytes of both BALB/c and athymic mice. In vivo experiments demonstrated that the antibody S1 clearly prolonged the survival of athymic mice which had been inoculated with a human liver carcinoma cell line. In addition, the antibody S1 significantly suppressed the human hepatoma line transplanted s.c. into nude mice. 125I-Labeled monoclonal antibody S1 revealed that the antibody accumulated significantly in the tumor mass. Many mononuclear cells were observed surrounding tumor cells when the antibody was given. This model system might be useful for analyzing the ADCC (or ADMC) mechanism in vivo. 相似文献
15.
Prerequisite for the induction of lymphokine-activated killer cells from T lymphocytes 总被引:5,自引:0,他引:5
H Sawada T Abo S Sugawara K Kumagai 《Journal of immunology (Baltimore, Md. : 1950)》1988,140(10):3668-3673
Human blood mononuclear cells were separated into Leu-11+7-NK, Leu-11-7+, and Leu-11-7-T cells by means of a combination of the Percoll gradient method and C-mediated cytolysis using mAb. When purified Leu-11+7-NK, Leu-11-7+, and Leu-11-7-T cells were cultured with rIL 2 (500 U/ml) for 6 days in a medium supplemented with 10% FCS, Leu-11+7-NK cells responded at the maximum level and Leu-11-7+ cells responded moderately as shown by both cell-proliferation response and cytotoxic activity generated. On the other hand, Leu-11-7-T cells did not respond at all to rIL-2. However, when Leu-11-7-T cells were cultured with rIL-2 in a medium supplemented with 10% autologous serum, they showed considerable responsiveness to rIL-2. In addition, much greater response to Leu-11-7-T cells were produced by the addition of monocytes. Monocyte cytokines, neither IL 1, IFN-gamma, TNF, nor their combination were able to substitute for monocytes in the induction culture. In contrast, the response level of Leu-11+7- NK cells remained unchanged irrespective of supplementation with autologous serum to medium or the addition of monocytes to the culture. These results indicated that culture conditions in the experiments significantly affected the results as to determination of lymphokine-activated killer cell precursors, especially the result pertaining to the conversion of T lymphocytes to lymphokine-activated killer cells. Under appropriate conditions, not only NK cells but also T cells are important precursors of lymphokine-activated killer cells. 相似文献
16.
Yuji Okawara David Ko Steven D. Morley Dietmar Richter Karl P. Lederis 《Cell and tissue research》1992,267(3):545-549
Summary In situ hybridization procedure with a 32P-labelled synthetic oligonucleotide probe was used to detect corticotropin-releasing factor-encoding messenger RNA (CRF mRNA) in the hypothalamus of the white sucker, Catostomus commersoni. Adjacent sections were immunostained by a sucker CRF-specific antiserum. CRF mRNA-containing neurons were identified by autoradiography in the magnocellular and parvocellular subdivisions of the preoptic nucleus (PON). Many of these neurons were also immunostained by sucker antiserum, showing the same distribution patterns. These results confirm the presence of CRF mRNA and CRF peptide in the white sucker hypothalamus and support the view that the magnocellular and parvocellular neurons of the PON may be involved in the control of adrenocorticotropic hormone secretion from the pituitary in the white sucker. 相似文献
17.
18.
K Tsuchiya S Tada K Gomi K Kitamoto C Kumagai G Tamura 《Bioscience, biotechnology, and biochemistry》1992,56(11):1849-1853
The Taka-amylase A gene (amyB) of Aspergillus oryzae is induced by starch or maltose. The molecular mechanism of the induction was investigated using a fusion of the amyB promoter and the Escherichia coli uidA gene encoding beta-glucuronidase (GUS). To identify the region responsible for high-level expression and regulation within the amyB promoter, a series of deletion promoters was constructed and introduced into the A. oryzae met locus by homologous recombination. Deletion of the region between -377 to -290 (the number indicates the distance in base pairs from the translation initiation point (+1) to the deletion end point) significantly reduced of the GUS activity, but slight reduction of the GUS activity was observed in deletions up to -377. Northern blot analysis showed that reduction of the GUS activity depended upon the expression level of the GUS gene. The region between -377 to -290 is suggested to include the sequence required directly for high-level expression and regulation of the amyB gene. 相似文献
19.
Flowering responses to light-breaks in photomorphogenic mutants of Arabidopsis thaliana, a long-day plant 总被引:9,自引:0,他引:9
Flowering response and plant form of photomorphogenic mutants (hy1, hy2, hy3, hy4 and hy5) of Arabidopsis thaliana (L.), a long-day plant, were examined in long and short days. There were only slight differences among genotypes including Landsberg wild type with respect to the flowering time under long days. The effect of 1 h light-(night)-breaks of far-red, red, blue and white light given in the middle of the dark period of plants grown under short days, was studied. Effects of far-red light applied at the end or the beginning of the main photoperiod on flowering and plant form were also examined. The light-breaks with all the above mentioned light qualities promoted floral initiation of all the genotypes including the wild type in terms of both the flowering time and the number of rosette leaves. In general, far-red light was most effective. It is possible to classify the hy-mutants into 3 groups by their responses to light-breaks under short day conditions: (a) Mutants hy2 and hy3, which have a reduced number of rosette leaves, and flower early. Red light is as effective as far-red light. The wavelength of light-breaks is relatively unimportant for flowering response. (b) Mutants hy4, hy5 and Landsberg wild type, which have a greater number of rosette leaves, and flower relatively late. The effectiveness of light-breaks is in the following order, far-red, blue, and red light, which is in reverse order to the transformation of phytochrome to the Pfr form. (c) Mutant hy1, which behaves anomalously with respect to relations between flowering time and number of rosette leaves; late flowering with reduced number of rosette leaves. Red, blue and far-red light are effective, but white light is ineffective for reducing the number of rosette leaves. When far-red light was given in the middle of the night or at the end of the main photoperiod, it markedly reduced the number of rosette leaves compared to those grown under short days for all the genotypes, while when applied at the beginning of the main photoperiod far-red light did not affect the number of rosette leaves. Different effects on the plant form dependent on the time of treatment with far-red light-breaks are also discussed. 相似文献
20.
Hidenori Shinkawa Masanori Sugiyama Yuji Hatada Takeshi Ohuchi Masao Udagawa Osamu Nimi 《Biotechnology letters》1991,13(8):537-542
Summary The bald mutants from streptomycin (SM)-producingStreptomyces griseus 2247 obtained by incubation at high temperature (36° C), designated as HT strains, lost resistance to their own antibiotic and scarcely produced the antibiotic. Although SM susceptibility in the mutant was due to loss of SM 6-phosphotransferase activity produced in the cell, the gene coding for the enzyme cloned from an HT strain was surely expressed inS. lividans 1326 as a host. Northern blot analysis showed that the corresponding RNA is not detected in the mutant, indicating that though the gene encoding SM 6-phosphotransferase, at least, the structural gene is not deleted in the cell, the expression is silent. 相似文献