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排序方式: 共有119条查询结果,搜索用时 31 毫秒
11.
Hiroki Takagi Shintaro Sugawara Tomoka Saito Haruka Tasaki Lu Yuanxue Guan Kaiyun Dong-Sheng Han Toshinari Godo Masaru Nakano 《Plant biotechnology reports》2011,5(2):187-195
The gesneriaceous perennial plant Titanotrichum oldhamii has beautiful foliage and attractive bright yellow flowers. However, breeding of T. oldhamii by conventional sexual hybridization may be difficult because sexual reproduction of this species is very rare. In the present
study, plant regeneration systems via both direct and indirect formation of adventitious shoots from leaf explants were established
as the first step toward breeding T. oldhamii by using biotechnological techniques. Adventitious shoots were formed efficiently on medium containing 0.1 mg l−1 benzyladenine. Histological observation showed that shoot formation on this medium occurred directly from leaf epidermal
cells without callus formation. On the other hand, leaf explants formed calluses on medium containing 0.1 mg l−1 2,4-dichlorophenoxyacetic acid. The calluses could be maintained by monthly subculturing to fresh medium of the same composition.
When the calluses were transferred to plant growth regulator-free medium, they formed adventitious shoots. Directly and indirectly
formed shoots rooted well on medium containing 0.1 mg l−1 indole-3-butyric acid. Plantlets thus obtained were successfully acclimatized and grew vigorously in the greenhouse. Flow
cytometry analysis indicated that no variation in the ploidy level was observed in plants regenerated via direct shoot formation,
whereas chromosome doubling occurred in several plants regenerated via indirect shoot formation. Regenerated plants with the
same ploidy level as the mother plants showed almost the same phenotype as the mother plants, whereas chromosome-doubled plants
showed apparent morphological alterations: they had small and crispate flowers, and round and deep green leaves. 相似文献
12.
Hiroshi Kamiya Hitoshi Ohshiro Yu Tabayashi Yoshihiro Kano Koji Mishima Toshiyuki Godo Masumi Yamamuro Osamu Mitamura Yu Ishitobi 《Landscape and Ecological Engineering》2011,7(1):53-64
In situ phosphorus release rates in three contiguous shallow brackish lakes were calculated by considering the amount of water
inflow, changes in salinity and phosphorus stock, and loading from phosphorus inflow based on monthly data. The annual amount
of sedimental phosphorus relative to that of phosphorus inflow was different for each of the three water bodies: 16% for Lake
Shinji, 3% for the Honjo area, and −8% for Lake Nakaumi, as estimated in a 10-year period from January 1993 to December 2002.
During the warm season, the quantity of phosphorus released surpassed sedimentation in these three water bodies. The low annual
sedimentation ratio in Lake Nakaumi is related to a large seawater backflow resulting in phosphorus removal, in addition to
a stable stratified structure promoting phosphorus release from sediment due to oxygen depletion in the lower layer. In Lake
Nakaumi, field data shows that if dissolved oxygen at the sediment surface falls below 2.54 mg L−1, phosphorus release from the sediment begins to be accelerated. 相似文献
13.
Shimatani T Inoue M Iwamoto K Hyogo H Yokozaki M Saeki T Tazuma S Horikawa Y Harada N 《Helicobacter》2005,10(3):256-265
BACKGROUND: Follicular gastritis is thought to be caused by Helicobacter pylori infection. However, the pathophysiology of it remains unclear. MATERIALS AND METHODS: We assessed gastric acidity in 15 patients with follicular gastritis, aged 20-37 years, using a 24-hour intragastric pH-metry, as well as by histologic and serologic evaluations; and compared it with that in other age-matched groups: 18 cases of H. pylori-positive antrum-predominant gastritis, 12 of pangastritis, and 24 H. pylori-negative normals. In eight cases with follicular gastritis, it was re-assessed 6 months after the eradication therapy for H. pylori. RESULTS: During nighttime, the percentage of time with intragastric pH above 3.0 in follicular gastritis was significantly higher than that in normals (p<.0001), and in antrum-predominant gastritis (p<.001), but was comparable with that in pangastritis. In the daytime period, this parameter in follicular gastritis was significantly higher than that in normal (p<.001), in antrum-predominant gastritis (p<.001), and in pangastritis (p<.05). Marked mononuclear cell and neutrophil infiltration but no apparent glandular atrophy were observed in both the antrum and corpus. Serum pepsinogen I/II ratio was significantly lower in follicular gastritis than that in normals (p<.0001) and in antrum-predominant gastritis (p<.001), whereas serum gastrin was significantly higher than that in normals (p<.0001), in antrum-predominant gastritis (p<.01) and in pangastritis (p<.05). After eradication for H. pylori, all of the parameters in follicular gastritis were altered to the same ranges as those in normals. CONCLUSIONS: In follicular gastritis, gastric acidity is significantly reduced, but can be normalized by eradication of H. pylori. It can thus be speculated that inflammatory cytokines or H. pylori-infection-induced prostaglandins might strongly inhibit gastric acid secretion in follicular gastritis. 相似文献
14.
Neurotransmitter release regulated by a MALS-liprin-alpha presynaptic complex 总被引:2,自引:0,他引:2
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Olsen O Moore KA Fukata M Kazuta T Trinidad JC Kauer FW Streuli M Misawa H Burlingame AL Nicoll RA Bredt DS 《The Journal of cell biology》2005,170(7):1127-1134
Synapses are highly specialized intercellular junctions organized by adhesive and scaffolding molecules that align presynaptic vesicular release with postsynaptic neurotransmitter receptors. The MALS/Veli-CASK-Mint-1 complex of PDZ proteins occurs on both sides of the synapse and has the potential to link transsynaptic adhesion molecules to the cytoskeleton. In this study, we purified the MALS protein complex from brain and found liprin-alpha as a major component. Liprin proteins organize the presynaptic active zone and regulate neurotransmitter release. Fittingly, mutant mice lacking all three MALS isoforms died perinatally with difficulty breathing and impaired excitatory synaptic transmission. Excitatory postsynaptic currents were dramatically reduced in autaptic cultures from MALS triple knockout mice due to a presynaptic deficit in vesicle cycling. These findings are consistent with a model whereby the MALS-CASK-liprin-alpha complex recruits components of the synaptic release machinery to adhesive proteins of the active zone. 相似文献
15.
The specific p38 mitogen-activated protein kinase pathway inhibitor FR167653 keeps insulitis benign in nonobese diabetic mice 总被引:2,自引:0,他引:2
The p38 mitogen-activated protein kinase (MAPK) pathway is important in Th1 immunity, macrophage activation, and apoptosis. Since they may be associated with beta-cell destruction during the development of type 1 diabetes, we investigated the role of the p38 MAPK pathway in female nonobese diabetic (NOD) mice. Phosphorylated p38 MAPK was observed immunohistochemically in CD4+ cells that had infiltrated into the islets and part of beta-cells, increasing in proportion to the severity of insulitis. Continuous oral administration of 0.08% FR167653, a specific p38 MAPK pathway inhibitor, significantly reduced the ex vivo production of interferon-gamma by splenic Th1 cells without affecting interleukin-4 production by Th2 cells. FR167653 administration from 4-30 weeks of age prevented NOD mice from developing diabetes without affecting the severity of insulitis. Treatment with FR167653 after insulitis had developed (i.e. from 10-30 weeks of age) also prevented diabetes, further suggesting that treatment with the p38 MAPK pathway inhibitor keeps insulitis benign in NOD mice, partly by inhibiting Th1 immunity. These findings suggest that p38 MAPK is a key mediator that switches insulitis from benign to destructive in the development of type 1 diabetes. 相似文献
16.
17.
We have evaluated the role of monofunctional heme-containing catalase encoded by cat-1 gene from the soil bacterium Comamonas terrigena N3H in the response to various forms of oxidative stress. Our results indicate that this constitutively expressed catalase
represents the major source for the defence of Comamonas terrigena cells against toxic peroxides but the cells can express also a second form of catalase that is bigger and its regulation
is probably more complicated. The sequence analysis confirmed the presence of highly conserved catalase sequence motifs in
two environmental strains of Comamonas terrigena but in those strains that were not exposed to oxidative stress, no such sequence motif could be detected. The results obtained
underline the importance of catalase expression in the defence mechanism against oxidative stress in bacterial cells. 相似文献
18.
Ando H Oshima Y Yanagihara H Hayashi Y Takamura T Kaneko S Fujimura A 《Biochemical and biophysical research communications》2006,346(4):1297-1302
Although a number of genes expressed in most tissues, including the liver, exhibit circadian regulation, gene expression profiles are usually examined only at one scheduled time each day. In this study, we investigated the effects of obese diabetes on the hepatic mRNA levels of various genes at 6-h intervals over a single 24-h period. Microarray analysis revealed that many genes are expressed rhythmically, not only in control KK mice but also in obese diabetic KK-A(y) mice. Real-time quantitative PCR verified that 19 of 23 putative circadianly expressed genes showed significant 24-h rhythmicity in both strains. However, obese diabetes attenuated these expression rhythms in 10 of 19 genes. More importantly, the effects of obese diabetes were observed throughout the day in only two genes. These results suggest that observation time influences the results of gene expression analyses of genes expressed circadianly. 相似文献
19.
The large subunit (HycE, 569 amino acids) of Escherichia coli hydrogenase 3 produces hydrogen from formate via its Ni–Fe-binding site. In this paper, we engineered HycE for enhanced hydrogen
production by an error-prone polymerase chain reaction (epPCR) using a host that lacked hydrogenase activity via the hyaB hybC hycE mutations. Seven enhanced HycE variants were obtained with a novel chemochromic membrane screen that directly detected hydrogen
from individual colonies. The best epPCR variant contained eight mutations (S2T, Y50F, I171T, A291V, T366S, V433L, M444I,
and L523Q) and had 17-fold higher hydrogen-producing activity than wild-type HycE. In addition, this variant had eightfold
higher hydrogen yield from formate compared to wild-type HycE. Deoxyribonucleic acid shuffling using the three most-active
HycE variants created a variant that has 23-fold higher hydrogen production and ninefold higher yield on formate due to a
74-amino acid carboxy-terminal truncation. Saturation mutagenesis at T366 of HycE also led to increased hydrogen production
via a truncation at this position; hence, 204 amino acids at the carboxy terminus may be deleted to increase hydrogen production
by 30-fold. This is the first random protein engineering of a hydrogenase. 相似文献
20.
Anaerobic bacteria have been used to produce 2,4-dihydroxylamino-nitrotoluene (2,4DHANT), a reductive metabolite of 2,4,6-trinitrotoluene
(TNT). Here, an aerobic TNT biodegrader Pseudomonas sp. strain TM15 produced 2,4DHANT as evidenced by the molecular ion with m/z of 199 identified from LC-TOFMS analyses. TNT
biodegradation with a high cell concentration (109 cells/ml) led to a significant accumulation of 2,4DHANT in the culture medium, as well as hydroxylamino-dinitrotoluenes (HADNTs),
although these products were not accumulated when a low cell concentration was used; also, the accumulation of diamino-nitrotoluene
and of an unidentified metabolite were observed in the culture medium with the high cell concentration (1010 cells/ml). 2,4DHANT overproduction was a function of the aeration speed since cultures with low aeration speeds (30 rpm)
had a 19-fold higher DHANT productivity than those aerated with high speeds (180 rpm); this indicates that molecular oxygen
was related to the formation of 2,4DHANT. The quantification of dissolved oxygen (DO) in the media demonstrated that the productivity
of 2,4DHANT was increased at low DO values. Moreover, supplying oxygen to the culture media produced a remarkable decrease
of 2,4DHANT accumulation; these results clearly indicate that high 2,4DHANT production was a consequence of the oxygen deficit
in the culture medium. This finding is useful for understanding the TNT biodegradation (bioremediation technology) in an anoxic
environment.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献