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排序方式: 共有119条查询结果,搜索用时 31 毫秒
31.
Toshinari Godo Miho Komori Emi Nakaoki Tomohisa Yukawa Kazumitsu Miyoshi 《In vitro cellular & developmental biology. Plant》2010,46(3):323-328
The effects of culture conditions on the asymbiotic germination of mature seeds of Calanthe tricarinata Lindl., an endangered terrestrial cool-climate orchid, were examined. Specifically, conditions such as illumination, temperature,
and the addition of plant growth regulators to the medium were studied. Mature seeds were harvested from plants that had been
collected in Toyama Prefecture, Japan, and maintained at the Botanic Gardens of Toyama. Solidified “New Dogashima” medium
was used as the basal medium, and it was supplemented with 6-benzyladenopurine (BA) or α-naphthalene acetic acid (NAA). White
light at 40 μmol m−2 s−1, with a 16-h photoperiod, inhibited the germination of seeds by 53–80%, as compared to dark controls in genotypes examined.
The optimal temperature for the germination of seeds in darkness was 20°C and the germination frequency reached 60%, whereas
it was only 28% at 25°C. While both NAA and BA stimulated germination, BA was more effective than NAA. After storage for 18 mo
at 5°C, seeds incubated on medium that contained 0.2 mg l−1 BA germinated at a frequency of 36%, which was twice that of seeds grown without any plant growth regulators. The frequency
of subsequent germination decreased during storage of seeds at 5°C for approximately 2 yr, dropping from 61% to 13%. The protocorms
obtained in this study were developed to plantlets readily after transferring to fresh 1/2 MS medium without any plant growth
regulators. They were successfully acclimatized in green house after two to three subcultures in vitro. The significant role of a reproducible protocol for the germination of mature seeds is discussed in terms of the ex situ conservation of endangered orchid species. 相似文献
32.
Murata M Suzuki T Midorikawa K Oikawa S Kawanishi S 《Free radical biology & medicine》2004,37(6):793-802
Interstrand DNA cross-linking has been considered to be the primary action mechanism of cyclophosphamide (CP) and its hydroperoxide derivative, 4-hydroperoxycyclophosphamide (4-HC). To clarify the mechanism of anti-tumor effects by 4-HC, we investigated DNA damage in a human leukemia cell line, HL-60, and its H(2)O(2)-resistant clone HP100. Apoptosis DNA ladder formation was detected in HL-60 cells treated with 4-HC, whereas it was not observed in HP100 cells. 4-HC significantly increased 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) formation, a marker of oxidative DNA damage, in HL-60 cells. On the other hand, CP did not significantly induce 8-oxodG formation and apoptosis in HL-60 cells under the same conditions as did 4-HC. Using (32)P-labeled DNA fragments from the human p53 tumor suppressor gene, 4-HC was found to cause Cu(II)-mediated oxidative DNA damage, but CP did not. Catalase inhibited 4-HC-induced DNA damage, including 8-oxodG formation, suggesting the involvement of H(2)O(2). The generation of H(2)O(2) during 4-HC degradation was ascertained by procedures using scopoletin and potassium iodide. We conclude that, in addition to DNA cross-linking, oxidative DNA damage through H(2)O(2) generation may participate in the anti-tumor effects of 4-HC. 相似文献
33.
Taichi Usui Masahiro Suzuki Toshinari Sato Hirokazu Kawagishi Kyoko Adachi Hiroshi Sano 《Glycoconjugate journal》1994,11(2):105-110
Transmannosylation from mannotriose (Man1-4Man1-4Man) to the 4-position at the nonreducing end N-acetylglucosaminyl residue ofN,N-diacetylchitobiose was regioselectively induced through the use of -d-mannanase fromAspergillus niger. The enzyme formed the trisaccharide Man1-4GlcNAc1-4GlcNAc (3.7% of the enzyme-catalysed net decrease ofN,N-diacetylchitobiose) from mannotriose as a donor andN,N-diacetylchitobiose as an acceptor. Mannobiose (Man1-4Man) was also shown to be useful as a donor substrate for the desired trisaccharide synthesis.Abbreviations Man
d-mannose
- (M
n) (n=1–5)
-linkedn-mer of mannose
- GlcNAc2
2-acetamido-2-deoxy--d-glucopyranosyl-(1–4)-2-acetamido-2-deoxy-d-glucose 相似文献
34.
Masaru?NakanoEmail author Keiko?Mizunashi Shigefumi?Tanaka Toshinari?Godo Masashi?Nakata Hiroyuki?Saito 《In vitro cellular & developmental biology. Plant》2004,40(3):274-278
Summary The liliaceous perennial plants, Tricyrtis spp., are cultivated as ornamental plants in Japan. Natural populations of several Japanese Tricyrtis spp. are severely threatened by indiscriminate collection and habitat destruction. In this study, a plant regeneration system
based on somatic embryogenesis has been developed for efficient clonal propagation of T. hirta, T. hirta var. albescens, T. formosana, T. formosana cv. Fujimusume, T. flava ssp. ohsumiensis, and T. macrantha ssp. macranthopsis. Flower tepal explants of these genotypes were cultured on media containing 2,4-dichlorophenoxyacetic acid (2,4-D) or 4-amino-3,5,6-trichloropicolinic
acid (picloram, PIC) alone or in combination with N-(1,2,3-thiadiazol-5-yl)-N′-phenylurea (thidiazuron, TDZ). Calluses induced on media containing 2,4-D produced somatic embryos following their transfer
to a plant growth regulator-free medium, indicating that these calluses were embryogenic. A combination of 4.5μM2,4-D and 0.45 μM TDZ was most effective for inducing embryogenic calluses from tepal explants. Among various explant sources, filaments were
most suitable for inducing embryogenic calluses on a medium containing 4.5μM 2,4-D and 0.45 μM TDZ. Embryogenic calluses were only obtained from filament explants for T. macrantha ssp. macranthopsis. Embryogenic calluses could be maintained by subculturing monthly onto the same medium, and a 1.5–3.5-fold increase in fresh
weight was obtained after 1 mo. of subculture. Depending on the plant genotype, 50–500 somatic embryos per 0.5g fresh weight
of embryogenic callus was obtained 1 mo. after transfer to a plant growth regulator-free medium. Most of the embryos developed
into plantlets, and they were successfully acclimatized to greenhouse conditions. Regenerated plants showed no alteration
in the ploidy level as indicated by chromosome observation and flow cytometric analysis. 相似文献
35.
Bacterial isolates Comamonas terrigena N3H (from soil contaminated with crude oil) and C. testosteroni (isolated from the sludge of a wastewater treatment plant), exhibit much higher total catalase activity than the same species from laboratory collection cultures. Electrophoretic resolution of catalases revealed only one corresponding band in cell-free extracts of both C. testosteroni cultures. Isolates of C. terrigena N3H exhibited catalase-1 and catalase-2 activity, whereas in the collection culture C. terrigena ATCC 8461 only catalase-1 was detected. The environmental isolates exhibited much higher resistance to exogenous H2O2 (20, 40 mmol/L) than collection cultures, mainly in the middle and late exponential growth phases. The stepwise H2O2-adapted culture of C. terrigena N3H, which was more resistant to oxidative stress than the original isolate, exhibited an increase of catalase and peroxidase activity represented by catalase-1. Pretreatment of cells with 0.5 mmol/L H2O2 followed by an application of the oxidative agent in toxic concentrations (up to 40 mmol/L) increased the rate of cell survival in the original isolate, but not in the H2O2-adapted variant. The protection of bacteria caused by such pretreatment corresponded with stimulation of catalase activity in pretreated culture. 相似文献
36.
In a previous study, we developed a novel cationic lipid consisting of polyamidoamine dendron of third generation and two dodecyl chains, designated as DL-G3, which in combination with a fusogenic lipid dioleoylphosphatidylethanolamine (DOPE) achieves efficient transfection of CV1 cells by synergetic action of the proton sponge effect and membrane fusion. This study examines the effect of serum on the transfection activity of the DL-G3-DOPE-plasmid DNA lipoplexes. The transfection activity of a lipoplex with a composition optimized in the absence of serum decreased markedly in the presence of serum. However, the lipoplexes that induce efficient transfection in the presence of serum were obtainable by controlling the charge ratio of the primary amine of the DL-G3 to the phosphate group (N/P ratio) and DOPE content. The complex, which exhibited the highest transfection activity in the presence of serum, has a lower N/P ratio and higher DOPE content than that optimized in the absence of serum. Whereas disintegration of these complexes was induced by addition of heparin, which is a polysaccharide with negatively charged groups, the complex that retained transfection activity in the presence of serum required more negative charges of heparin for complex disintegration. That result implies its higher stability against negatively charged serum proteins. Comparison of the serum-resistant complex with some commercially available transfection reagents, such as Lipofectamine and SuperFect, indicates that the DL-G3 complex achieved more efficient transfection of these cells in the presence of serum. 相似文献
37.
An efficient protocol was established for the cryopreservation of immature seeds of a terrestrial orchid, Bletilla striata. Immature seeds collected 2–4 months after pollination (MAP) were treated using three different cryogenic procedures: (1) direct plunging into liquid nitrogen, (2) vitrification, and (3) vitrification with preculture. When immature seeds collected 3 MAP and 4 MAP were precultured for 3 days on New Dogashima medium supplemented with 0.3 M sucrose and cryopreserved by vitrification, the survival rate after preservation, as assessed by staining with 2,3,5-triphenyltetrazolium chloride, was 92% and 81%, respectively. Immature seeds thus treated showed no decrease in germination rate relative to untreated immature seeds, and they developed into normal plantlets in vitro. 相似文献
38.
Noboru Shibasaki Toshinari Yamasaki Toru Kanno Ryuichiro Arakaki Hiromasa Sakamoto Noriaki Utsunomiya Takahiro Inoue Tatsuaki Tsuruyama Eijiro Nakamura Osamu Ogawa Tomomi Kamba 《PloS one》2015,10(6)
Vascular endothelial growth factor (VEGF) and mammalian target of rapamycin are well-known therapeutic targets for renal cell carcinoma (RCC). Sunitinib is an agent that targets VEGF receptors and is considered to be a standard treatment for metastatic or unresectable clear cell RCC (ccRCC). However, ccRCC eventually develops resistance to sunitinib in most cases, and the mechanisms underlying this resistance are not fully elucidated. In the present study, we established unique primary xenograft models, KURC1 (Kyoto University Renal Cancer 1) and KURC2, from freshly isolated ccRCC specimens. The KURC1 xenograft initially responded to sunitinib treatment, however finally acquired resistance. KURC2 retained sensitivity to sunitinib for over 6 months. Comparing gene expression profiles between the two xenograft models with different sensitivity to sunitinib, we identified interleukin 13 receptor alpha 2 (IL13RA2) as a candidate molecule associated with the acquired sunitinib-resistance in ccRCC. And patients with high IL13RA2 expression in immunohistochemistry in primary ccRCC tumor tends to have sunitinib-resistant metastatic site. Next, we showed that sunitinib-sensitive 786-O cells acquired resistance in vivo when IL13RA2 was overexpressed. Conversely, shRNA-mediated knockdown of IL13RA2 successfully overcame the sunitinib-resistance in Caki-1 cells. Histopathological analyses revealed that IL13RA2 repressed sunitinib-induced apoptosis without increasing tumor vasculature in vivo. To our knowledge, this is a novel mechanism of developing resistance to sunitinib in a certain population of ccRCC, and these results indicate that IL13RA2 could be one of potential target to overcome sunitinib resistance. 相似文献
39.
Godo Toshinari Hashimoto Toshimasa Nakata Masashi Miyoshi Kazumitsu 《In vitro cellular & developmental biology. Plant》2020,56(2):230-235
In Vitro Cellular & Developmental Biology - Plant - We examined the effects of culture conditions, namely, illumination, temperature and the addition of 6-benzylaminopurine (BAP) to the... 相似文献
40.
Malz F Yoneda Y Kawada T Mereiter K Kosma P Rosenau T Jäger C 《Carbohydrate research》2007,342(1):65-70
Double Quantum (DQ) NMR, which utilizes the magnetic dipole interaction between the (13)C atoms, was used for the complete assignment of the (13)C NMR resonances to the corresponding carbon ring positions for the monoclinic and triclinic allomorphs of methyl 4'-O-methyl-beta-D-cellobioside-(13)C(12)(1-(13)C(12)), a cellodextrin model compound of cellulose (13)C-perlabeled at the cellobiose core. The through-space interactions were used to identify the direct chemical bonds between adjacent carbon atoms in the rings. More importantly, the (13)C NMR signals of the carbon sites C1' and C4 involved in the glycosidic bond were identified. This allowed for the complete (13)C chemical shift assignment, that when combined with the X-ray crystallography data provides a complete characterization. 相似文献