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81.
82.
Santos LO Gonzales TA Ubeda BT Monte Alegre R 《Applied microbiology and biotechnology》2007,77(4):763-769
A strategy of experimental design using a fractional factorial design (FFD) and a central composite rotatable design (CCRD)
were carried out with the aim to obtain the best conditions of temperature (20–30°C), agitation rate (100–300 rpm), initial
pH (5.0–7.0), inoculum concentration (5–15%), and glucose concentration (30–70 g/l) for glutathione (GSH) production in shake-flask
culture by Saccharomyces cerevisiae ATCC 7754. By a FFD (25–2), the agitation rate, temperature, and pH were found to be significant factors for GSH production. In CCRD (22) was obtained a second-order model equation, and the percent of variation explained by the model was 95%. The results showed
that the optimal culture conditions were agitation rate, 300 rpm; temperature, 20°C; initial pH, 5; glucose, 54 g/l; and inoculum
concentration, 5%. The highest GSH concentration (154.5 mg/l) was obtained after 72 h of fermentation. 相似文献
83.
Mechanical stress is thought to regulate the expression of genes in the periodontal ligament (PDL) cells. Using a microarray approach, we recently identified a regulator of G-protein signaling 2 (RGS2) as an up-regulated gene in the PDL cells under compressive force. The RGS protein family is known to turn off G-protein signaling. G-protein signaling involves the production of cAMP, which is thought to be one of the biological mediators in response to mechanical stress. Here, we investigated the role of RGS2 in the PDL cells under mechanical stress. PDL cells derived from the ligament tissues of human premolar teeth were cultured in collagen gels and subjected to static compressive force. Compressive force application time-dependently enhanced RGS2 expression and intracellular cAMP levels. To examine the interrelationship between RGS2 and cAMP, the PDL cells were treated with 2',5'-dideoxyadenosine (DDA), an inhibitor of adenyl cyclase, or antisense S-oligonucleotide (S-ODN) to RGS2 under compressive force. DDA dose-dependently inhibited RGS2 stimulated by compressive force. Blockage of RGS2 by antisense S-ODN elevated the cAMP levels compared with controls. These results indicate that cAMP stimulates RGS2 expression, which in turn leads to a decrease in the cAMP production by inactivating the G-protein signaling in the mechanically stressed PDL cells. 相似文献
84.
The toxicity of three common antibiotics (streptomycin sulfate, tetracycline hydrochloride, and tylosin tartrate) to the freshwater
rotifer Brachionus calyciflorus and brackish-water rotifer B. plicatilis was investigated using full-lifespan exposure durations. Effects of each antibiotic on lifespan, lifetime reproduction, and
Malthusian parameter were assessed at seven nominal concentrations (ranging from 5.6 mg l−1 to 2,000 mg l−1) and a negative control. Lowest Observed Effect Concentrations (LOECs) were determined for reproduction and lifespan, while
1%, 10%, 25%, and 50% Inhibitory Concentrations (IC1, IC10, IC25, IC50) and 95% confidence intervals were estimated for all three endpoints. LOECs ranged from 5.6 mg l−1 to 90 mg l−1, with all LOECs less than 90 mg l−1 occurring in B. calyciflorus. The lowest IC1 concentrations were 3.91 mg l−1 for the effect of tetracycline on lifetime reproduction in B. calyciflorus and 4.06 mg l−1 for the effect of tylosin on lifetime reproduction in B. plicatilis. Overall, lifetime reproduction was the most sensitive endpoint and the Malthusian parameter was the least sensitive. IC1 values for lifetime reproduction were roughly one to two orders of magnitude lower than the corresponding IC50 values.
Guest editors: S. S. S. Sarma, R. D. Gulati, R. L. Wallace, S. Nandini, H. J. Dumont and R. Rico-Martínez
Advances in Rotifer Research 相似文献
85.
C. Granado-Lorencio J. Lobón Cerviá C. R. M. Araujo Lima 《Biodiversity and Conservation》2007,16(3):679-692
The Neotropical region is renowned for its high biodiversity, and the Amazon River basin contains the highest number of fish
species of any river system in the world. In recent years, habitat fragmentation and exploitation of biotic resources have
threatened biological integrity and provoked to need for sustainable management and conservation of the Amazon River system.
We studied 36 floodplain lakes along 2000 km of the Amazon River. The fish assemblages associated with flood forests are moderately
diverse, with low species dominance and reduced populations. To detect nestedness of fish assemblage composition in floodplain
lakes, a nested subset analysis was performed on species presence–absence. The incidence matrix (species × lakes) was maximally
packed using the Nestedness Temperature Calculator software. The results of ranking lakes and species allow us to establish
targets for conservation. Such strategy for sustainable management should be focused on maintaining the Amazonian biodiversity. 相似文献
86.
Yamile Gonzlez Aparecida S. Tanaka Izaura Y. Hirata Maday Alonso del Rivero Maria L.V. Oliva Mariana S. Araujo Maria A. Chvez 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2007,146(4):506
Human neutrophil elastase inhibition was detected in a crude extract of the marine snail Cenchritis muricatus (Gastropoda, Mollusca). This inhibitory activity remained after heating this extract at 60 °C for 30 min. From this extract, three human neutrophil elastase inhibitors (designated CmPI–I, CmPI–II and CmPI–III) were purified by affinity and reversed-phase chromatographies. Homogeneity of CmPI–I and CmPI–II was confirmed, while CmPI–III showed a single peak in reversed-phase chromatography, but heterogeneity in SDS-PAGE with preliminary molecular masses in the range of 18.4 to 22.0 kDa. In contrast, MALDI-TOF mass spectrometry of CmPI–I and CmPI–II showed that these inhibitors are molecules of low molecular mass, 5576 and 5469 Da, respectively. N-terminal amino acid sequences of CmPI–I (6 amino acids) and CmPI–II (20 amino acids) were determined. Homology to Kazal-type protease inhibitors was preliminarily detected for CmPI–II. Both inhibitors, CmPI–I and CmPI–II are able to inhibit human neutrophil elastase strongly, with equilibrium dissociation constant (Ki) values of 54.2 and 1.6 nM, respectively. In addition, trypsin and pancreatic elastase were also inhibited, but not plasma kallikrein or thrombin. CmPI–I and CmPI–II are the first human neutrophil elastase inhibitors described in a mollusk. 相似文献
87.
Murine Schistosoma mansoni infection is related to an increased contraction of portal vein in response to 5-hydroxytryptamine (5-HT). The present study addressed a putative alteration of ion channels and enzymes involved in vascular contraction. In control group, either inhibition of K+ channels sensitive to ATP (K(ATP)) or Ca2+ (BK(Ca)) increased 5-HT-induced contraction, but the same did not occur in infected mice. On the other hand, inhibition of p38 MAP kinase markedly decreased the vascular contraction to 5-HT in the infected mice with minor effects in the control group. Accordingly, we observed a higher density of phospho-p38 MAP kinase, that refers to the fully active state of the enzyme, in portal veins from infected mice as compared to control animals. These results suggest that the reduced function of K(ATP) and BK(Ca) channels along with an increased contribution of p38 MAP kinase contribute to the increased contraction of portal veins to 5-HT observed in murine schistosomiasis. 相似文献
88.
Ana Claudia Guerra Araujo Rosana Falcão Vera Tavares de Campos Carneiro 《Sexual plant reproduction》2007,20(3):109-121
Gametophytic organization, fertilization and reproductive success are described for the fertile diploid Brachiaria brizantha accession BRA-002747 which is being raised for use in Brachiaria breeding programs, as well as to understand and control of apomixis in this genus. The current paper reports on reproductive
biology and analysis of seed set in field experiments during three consecutive years. Unsuccessful seed production in this
plant is believed to correlate with early inbreeding depression, based on the reproductive features analyzed. Caryopsis development
was observed using differential interference contrast microscopy with seed set determined by the number of self- and open-pollinated
pistils that fully developed into viable seeds. Developing and mature female and male gametophytes were observed in the context
of flower phenology, morphology and anthesis patterns. Pollen viability was determined by acetocarmine staining and by observation
of germination in vivo, which was also used to observe pollen tube/pistil interaction. Although normal development was observed
in floral structures, anthesis and gametophytes, seed set was low, with 2 and 6% in self- and open-pollination, respectively,
producing seed. Variations observed in the female organs, such as the presence of a hermaphrodite flower in 50% of the inferior
floscules and the presence of multiple embryo sacs of the Polygonum type within the same ovule in 15% of the pistils, are
not related to low fertility. The majority of pollen grains are viable, in spite of the reduced number of pollen tubes within
the style and ovary carpel, and a developing caryopsis was observed in 70% of self-pollinated pistils, indicating successful
double fertilization from 2 days after anthesis (DAA). Nevertheless, abortion gradually increased from 2 until 7 DAA and remains
elevated until 12 DAA, when caryopsis maturity is achieved. These data confirm low seed set in this accession and indicate
that low fertility is not a consequence of abnormalities, either in the floral or gamete structures, or pollen tube rejection,
but most likely a consequence of inbreeding depression. 相似文献
89.
Sidders B Withers M Kendall SL Bacon J Waddell SJ Hinds J Golby P Movahedzadeh F Cox RA Frita R Ten Bokum AM Wernisch L Stoker NG 《Genome biology》2007,8(12):R265-13
We describe an analysis, applicable to any spotted microarray dataset produced using genomic DNA as a reference, that quantifies prokaryotic levels of mRNA on a genome-wide scale. Applying this to Mycobacterium tuberculosis, we validate the technique, show a correlation between level of expression and biological importance, define the complement of invariant genes and analyze absolute levels of expression by functional class to develop ways of understanding an organism's biology without comparison to another growth condition. 相似文献
90.
Gong KW Zhao W Li N Barajas B Kleinman M Sioutas C Horvath S Lusis AJ Nel A Araujo JA 《Genome biology》2007,8(7):R149