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991.
Pelletier L Ozlü N Hannak E Cowan C Habermann B Ruer M Müller-Reichert T Hyman AA 《Current biology : CB》2004,14(10):863-873
BACKGROUND: The centrosome is composed of a centriole pair and pericentriolar material (PCM). By marking the site of PCM assembly, the centrioles define the number of centrosomes present in the cell. The PCM, in turn, is responsible for the microtubule (MT) nucleation activity of centrosomes. Therefore, in order to assemble a functional bipolar mitotic spindle, a cell needs to control both centriole duplication and PCM recruitment. To date, however, the molecular mechanisms that govern these two processes still remain poorly understood. RESULTS: Here we show that SPD-2 is a novel component of the C. elegans centrosome. SPD-2 localizes to the centriole throughout the cell cycle and accumulates on the PCM during mitosis. We show that SPD-2 requires SPD-5 for its accumulation on the PCM and that in the absence of SPD-2, centrosome assembly fails. We further show that centriole duplication is also defective in spd-2(RNAi) embryos, but not in spd-5(RNAi) embryos, where PCM recruitment is efficiently blocked. CONCLUSIONS: Taken together, our results suggest that SPD-2 may link PCM recruitment and centriole duplication in C. elegans. SPD-2 shares homology with a human centrosome protein, suggesting that this key component of the C. elegans centrosome is evolutionarily conserved. 相似文献
992.
Se-Wook Jung Tae-Kwon Kim Kwang-Woo Lee Yong-Hyun Lee 《Biotechnology and Bioprocess Engineering》2007,12(3):207-212
The catalytic properties of β-cyclodextrin glucanotransferase (β-CGTase) from alkalophilicBacillus sp. BL-12 specific for the intermolecular transglycosylation of stevioside were investigated. The molecular mass of purified
β-CGTase by ultra-filtration and β-cyclodextrin polymer affinity chromatography was estimated to be 90 kDa, which is high
compared to other known bacterial CGTases. The optimal pH and temperature were 9.0 and 50°C, respectively, and thermal stability
at 40°C was elevated 10-fold in the presence of 1% maltodextrin. The kinetic parameters of the new β-CGTase from alkalophilicBacillus sp. BL-12 indicate that it is more suitable for transglycosylation than the cyclization reaction. Maltodextrin was the most
suitable glycosyl donor for transglycosylation of stevioside. The transglycosylation of stevioside was carried out using 60
units of CGTase per gram of maltodextrin, 20 g/L stevioside as the glycosyl acceptor, and 50 g/L maltodextrin as the gycosyl
donor at 40°C for 6 h, and a conversion yield of stevioside as high as 76% was obtained. 相似文献
993.
Inventory and monitoring of wine microbial consortia 总被引:2,自引:0,他引:2
The evolution of the wine microbial ecosystem is generally restricted to Saccharomyces cerevisiae and Oenococcus oeni, which are the two main agents in the transformation of grape must into wine by acting during alcoholic and malolactic fermentation,
respectively. But others species like the yeast Brettanomyces bruxellensis and certain ropy strains of Pediococcus parvulus can spoil the wine. The aim of this study was to address the composition of the system more precisely, identifying other
components. The advantages of the polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) approach to
wine microbial ecology studies are illustrated by bacteria and yeast species identification and their monitoring at each stage
of wine production. After direct DNA extraction, PCR-DGGE was used to make the most exhaustive possible inventory of bacteria
and yeast species found in a wine environment. Phylogenetic neighbor-joining trees were built to illustrate microbial diversity.
PCR-DGGE was also combined with population enumeration in selective media to monitor microbial changes at all stages of production.
Moreover, enrichment media helped to detect the appearance of spoilage species. The genetic diversity of the wine microbial
community and its dynamics during winemaking were also described. Most importantly, our study provides a better understanding
of the complexity and diversity of the wine microbial consortium at all stages of the winemaking process: on grape berries,
in must during fermentation, and in wine during aging. On grapes, 52 different yeast species and 40 bacteria could be identified.
The diversity was dramatically reduced during winemaking then during aging. Yeast and lactic acid bacteria were also isolated
from very old vintages. B. bruxellensis and O. oeni were the most frequent. 相似文献
994.
Zaprionus indianus is a recent invader in Brazil and was probably introduced from the West Afrotropical zone. So far, studies regarding its
chromosomal polymorphism were limited to India. We found that Brazilian populations were very different from Indian ones.
Five new inversions have been discovered. In(II)A, already described in India, where it is quite common, has also been found in Brazil, where it is very rare. The X-chromosome
has three inversions; In(X)Na, In(X)Ke and In(X)Eg, which are frequent in all Brazilian populations studied. In every case, we observed strong linkage disequilibrium among
these gene arrangements. During the primary collection period (2001–2002), we noticed a significant positive correlation between
the frequency of these inversions and latitude, but this was not confirmed in later investigations. Rearrangement In(IV)EF was also common in all populations, while inversion In(V)B was only found in southern populations. Our data suggest that the founders that recently invaded Brazil were polymorphic
for the six inversions observed. The place of origin might be identified more precisely by investigating West African populations.
In order to facilitate further investigations, we present an updated polytene chromosome photomap, locating the breakpoints
of every inversion observed in Brazilian populations.
Galina Ananina and Cláudia Rohde contributed equally to this work 相似文献
995.
Marine bacteria have recently attracted attention as potentially useful candidates for the production of practical materials
from marine ecosystems, including the oceanic carbon dioxide cycle. The advantages of using marine bacteria for the biosynthesis
of poly(hydroxyalkanoate) (PHA), one of the eco-friendly bioplastics, include avoiding contamination with bacteria that lack
salt-water resistance, ability to use filtered seawater as a culture medium, and the potential for extracellular production
of PHA, all of which would contribute to large-scale industrial production of PHA. A novel marine bacterium, Vibrio sp. strain KN01, was isolated and characterized in PHA productivity using various carbon sources under aerobic and aerobic–anaerobic
marine conditions. The PHA contents of all the samples under the aerobic–anaerobic condition, especially when using soybean
oil as the sole carbon source, were enhanced by limiting the amount of dissolved oxygen. The PHA accumulated using soybean
oil as a sole carbon source under the aerobic–anaerobic condition contained 14% 3-hydroxypropionate (3HP) and 3% 5-hydroxyvalerate
(5HV) units in addition to (R)-3-hydroxybutyrate (3HB) units and had a molecular weight of 42 × 103 g/mol. The present result indicates that the activity of the beta-oxidation pathway under the aerobic–anaerobic condition
is reduced due to a reduction in the amount of dissolved oxygen. These findings have potential for use in controlling the
biosynthesis of long main-chain PHA by regulating the activity of the beta-oxidation pathway, which also could be regulated
by varying the dissolved oxygen concentration. 相似文献
996.
A significant macrophage and T-cell infiltrate commonly occurs in inflammatory joint conditions such as rheumatoid arthritis
that have significant bone destruction. Cytokines produced by activated macrophages and T cells are implicated in arthritis
pathogenesis and are involved in osteoclast-mediated bone resorption. The scope of the present review is to analyze current
knowledge and to provide a better understanding of how macrophage-derived factors promote the differentiation of a novel T-helper
subset (Th17) that promotes osteoclast formation and activation. 相似文献
997.
Ping-Jung Yi Cheng-Kang Pai Je-Ruei Liu 《World journal of microbiology & biotechnology》2011,27(5):1035-1043
The worldwide contamination of cereals, oilseeds, and other crops by mycotoxin-producing moulds is a significant problem.
Mycotoxins have adverse effects on humans and animals that result in illnesses and economic losses. Reduction or elimination
of mycotoxin contamination in food and feed is an important issue. This study aimed to screen soil bacteria for degradation
of zearalenone (ZEN). A pure culture of strain CK1 isolated from soil samples showed most capable of degradation of ZEN. Using
physiological, biochemical, and 16S rRNA gene sequence analysis methods, CK1 was identified as Bacillus licheniformis. Addition of 2 ppm of ZEN in Luria–Bertani (LB) medium, B. licheniformis CK1 decreased 95.8% of ZEN after 36 h of incubation. In ZEN-contaminated corn meal medium, B. licheniformis CK1 decreased more than 98% of ZEN after 36 h of incubation. In addition, B. licheniformis CK1 was non-hemolytic, non-enterotoxin producing, and displayed high levels of extracellular xylanase, cellulase, and protease
activities. These findings suggest that B. licheniformis CK1 could be used to reduce the concentrations of ZEN and improve the digestibility of nutrients in feedstuffs simultaneously. 相似文献
998.
Greenhouse hydroponic experiments were conducted using Cd-sensitive (Xiushui63) and tolerant (Bing97252) rice genotypes to
evaluate genotypic differences in response of photosynthesis and phytochelatins to Cd toxicity in the presence of exogenous
glutathione (GSH). Plant height, chlorophyll content, net photosynthetic rate (Pn), and biomass decreased in 5 and 50 μM Cd
treatments, and Cd-sensitive genotype showed more severe reduction than the tolerant one. Cadmium stress caused decrease in
maximal photochemical efficiency of PSII (Fv/Fm) and effective PSII quantum yield [Y(II)] and increase in quantum yield of
regulated energy dissipation [Y(NPQ)], with changes in Cd-sensitive genotype being more evident. Cadmium-induced phytochelatins
(PCs), GSH, and cysteine accumulation was observed in roots of both genotypes, with markedly higher level in PCs and GSH on
day 5 in Bing97252 compared with that measured in Xiushui63. Exogenous GSH significantly alleviated growth inhibition in Xiushui63
under 5 μM Cd and in both genotypes in 50 μM Cd. External GSH significantly increased chlorophyll content, Pn, Fv/Fm, and
Y(II) of plants exposed to Cd, but decreased Y(NPQ) and the coefficient of non-photochemical quenching (qN). GSH addition
significantly increased root GSH content in plants under Cd exposure (except day 5 of 50 μM Cd) and induced up-regulation
in PCs of 5 μM-Cd-treated Bing97252 throughout the 15-day and Xiushui63 of 5-day exposure. The results suggest that genotypic
difference in the tolerance to Cd stress was positively linked to the capacity in elevation of GSH and PCs, and that alleviation
of Cd toxicity by GSH is related to significant improvement in chlorophyll content, photosynthetic performance, and root GSH
levels. 相似文献
999.
1000.
Xiaokun Sun Linzhi Dai Hang Zhang Xuejun He Fandi Hou Wengao He Shijun Tang Dong Zhao 《Neurochemical research》2018,43(7):1383-1391
Neuritin is an extracellular glycophosphatidylinositol-linked protein that promotes neuronal survival, differentiation, function, and repair, but the exact mechanism of this neuroprotective effect remains unclear. Meanwhile, endoplasmic reticulum stress (ERS) induced apoptosis is attracting increased attention. In this work, we hypothesized that neuritin inhibited ERS to protect cortical neurons. To check this hypothesis, we exposed primary cultured cortical neurons to oxygen and glucose deprivation (OGD) for 45 min followed by reperfusion (R) to activate ERS. We then performed resuscitation for 6, 12, 24, and 48 h. ERS-related factors such as glucose-regulated protein 78 (GRP78), caspase-12 and CHOP were detected by Western blotting and quantitative real-time polymerase chain reaction assay. Apoptosis was assessed by Annexin V binding and propidium iodide staining. Ultrastructural changes of endoplasmic reticulum were observed under a transmission electron microscope. Results showed that GRP78 expression significantly increased at 12, 24, and 48 h and peaked at 24 h. Caspase-12 and CHOP expression significantly increased in a time-dependent manner at 12, 24, and 48 h. GRP78, caspase-12 and CHOP expression as well as apoptosis rate of primary cultured neurons and the ultrastructural changes of endoplasmic reticulum in the OGD/R?+?neuritin group significantly improved compared with the OGD/R group. In conclusion, the neuroprotection function of neuritin may be involved in ERS pathways. 相似文献