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31.
Takuji Tanaka Yumiko Yasui Takahiro Tanaka KM Wahidur Rahman 《Chemico-biological interactions》2009,177(2):128-136
The inhibitory effects of exogenous melatonin (MEL) on colon oncogenesis were investigated using an azoxymethane (AOM)/dextran sodium sulfate (DSS) rat model. Male F344 rats initiated with a single intraperitoneal injection of AOM (20 mg/kg bw) were promoted by 1% (w/v) DSS in drinking water for 7 days. They were then given 0.4, 2 or 10 ppm MEL in drinking water for 17 weeks. At week 20, the development of colonic adenocarcinoma was significantly inhibited by the administration with MEL dose-dependently. MEL exposure modulated the mitotic and apoptotic indices in the colonic adenocarcinomas that developed and lowered the immunohistochemical expression of nuclear factor kappa B, tumor necrosis factor α, interleukin-1β and STAT3 in the epithelial malignancies. These results may indicate the beneficial effects of MEL on colitis-related colon carcinogenesis and a potential application for inhibiting colorectal cancer development in the inflamed colon. 相似文献
32.
Flow cytometry was used to evaluate the effects of hyperosmotic stress on cell-cycle distribution and cell-associated immunoglobulins
for murine hybridoma cells grown in batch culture. Paraformaldehyde/methanol fixation substantially increased the fluorescence
signal for intracellular immunoglobulins compared to ethanol fixation. For surface immunoglobulins, similar fluorescence signals
were observed regardless of fixation method. Dual staining of immunoglobulins and cellular DNA was employed to determine immunoglobulin
pool size as a function of cell-cycle phase. The intracellular immunoglobulin pool sizes increased as the cells progressed
through the cell cycle for both control and hyperosmotic cultures. For control cultures, the immunoglobulin pool size increased
during the exponential phase of culture, followed by a decrease as the cultures entered stationary phase. In contrast, hyperosmotic
cultures showed an initial decrease in immunoglobulin pool size upon the application of osmotic shock, followed by an increase
to a level above that of control cultures. This behavior was observed in all phases of the cell cycle. In addition, hyperosmotic
cultures exhibited an increase in cell size when compared to control cultures. When normalized for cell size, the intracellular
immunoglobulin concentration in hyperosmotic cultures was initially lower than in control cultures and subsequently increased
to slightly above the level of control cells. Cells in all phases of the cell cycle behaved in a similar manner. There was
no apparent relationship between the intracellular antibody concentration and the rate of antibody secretion. 相似文献
33.
Kazunori?Matsumotosolokmatsu@hotmail.com; MK maskohda@sci.osaka-cu.ac.jp" title="KM solokmatsu@hotmail.com; MK maskohda@sci.osaka-cu.ac.jp" itemprop="email" data-track="click" data-track-action="Email author" data-track-label="">Email author Masanori?Kohda 《Ichthyological Research》2004,51(4):354-359
Territorial defense of nonbreeding female Neolamprologus tetracanthus, a shrimp-eating Tanganyikan cichlid, was investigated. Females defended territories (=home ranges, ca. 1m across) against a variety of intruding fishes. Conspecific females were usually attacked outside the territories, heterospecific benthivores (shrimp eaters) and omnivores near the border of the territories, and piscivores, algae and detritus feeders, and herbivores inside the territories. Females used some parts of the sandy substrate in the territories for foraging (foraging areas). Territorial defense prevented most of the conspecific females and benthivores from intruding into the foraging areas. In omnivores, piscivores, and algae and detritus feeders, about half the intruders were repelled from the foraging areas, although herbivores were infrequently repelled in the areas. Soon after removal of the resident females, many food competitors invaded the foraging areas and eagerly devoured prey, suggesting that the territories are maintained for food resource protection from these competitors. Females are likely to discriminate intruding fishes and change their territorial defense primarily on the basis of the degree of dietary overlap, resulting in monofunctional serial territories. 相似文献
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35.
Vesa?P?Hyt?nen Juha?AE?M??tt? Heidi?Kidron Katrin?K?Halling Jarno?H?rh? Tuomas?Kulomaa Thomas?KM?Nyholm Mark?S?Johnson Tiina?A?Salminen Markku?S?Kulomaa Tomi?T?AirenneEmail author 《BMC biotechnology》2005,5(1):28
Background
The chicken avidin gene family consists of avidin and several avidin related genes (AVRs). Of these gene products, avidin is the best characterized and is known for its extremely high affinity for D-biotin, a property that is utilized in numerous modern life science applications. Recently, the AVR genes have been expressed as recombinant proteins, which have shown different biotin-binding properties as compared to avidin. 相似文献36.
37.
Coregulation of beta-galactoside uptake and hydrolysis by the hyperthermophilic bacterium Thermotoga neapolitana
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Regulation of the beta-galactoside transport system in response to growth substrates in the extremely thermophilic anaerobic bacterium Thermotoga neapolitana was studied with the nonmetabolizable analog methyl-beta-D-thiogalactopyranoside (TMG) as the transport substrate. T. neapolitana cells grown on galactose or lactose accumulated TMG against a concentration gradient in an intracellular free sugar pool that was exchangeable with external galactose or lactose and showed induced levels of beta-galactosidase. Cells grown on glucose, maltose, or galactose plus glucose showed no capacity to accumulate TMG, though these cells carried out active transport of the nonmetabolizable glucose analog 2-deoxy-D-glucose. Glucose neither inhibited TMG uptake nor caused efflux of preaccumulated TMG; rather, glucose promoted TMG uptake by supplying metabolic energy. These data show that beta-D-galactosides are taken up by T. neapolitana via an active transport system that can be induced by galactose or lactose and repressed by glucose but which is not inhibited by glucose. Thus, the phenomenon of catabolite repression is present in T. neapolitana with respect to systems catalyzing both the transport and hydrolysis of beta-D-galactosides, but inducer exclusion and inducer expulsion, mechanisms that regulate permease activity, are not present. Regulation is manifest at the level of synthesis of the beta-galactoside transport system but not in the activity of the system. 相似文献
38.
Hassan Anwarul KM; Moriya Shigeki; Baumann Paul; Yoshikawa Hiroshi; Ogasawara Naotake 《DNA research》1996,3(6):415-419
Buchnera aphidicola is an intracellular prokaryote (endosymbiont)that lives in the body cavity of the aphid. Phylogenetic studiesindicated that it is closely related to Escherichia coli andmembers of Enterobacteria. The gene order of the region containingthe dnaA gene is well conserved in many bacteria. Seven genesof the endosymbiont of the aphid Schizaphis graminum, gyrB,dnaN, dnaA, rpmH, rnpA, yidD, and 60K, were found to be homologousin sequence and relative location to those of E. coli. We havefurther sequenced the region downstream of the 60K gene to elucidatethe boundary of the conserved region, and found that one moregene, thdF , is conserved. The comparison of gene organizationsof the dnaA region of the related bacteria supported the closephylogenetic relationship of B. aphidicola to E. coli. In addition,we have identified groES and groEL genesnext to the thdF gene.GroEL protein was reported to be expressed at an elevated levelin the endosymbionts of aphids, and is considered to play animportant role in their association with the aphid host. Comparisonof the structure of the groE operon with that of the endosymbiontof the aphid Acyrthosiphon pisum revealed the conservation ofa sequence resembling the E. coli consensus heat shock promoter,and this sequence may be responsible for the high expressionof the groEL gene in aphid endosymbionts. 相似文献
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BACKGROUND: By 2016, the proportion of Canadians older than 65 years of age will increase to 16%, and there will be an increase in the absolute number of cases of cardiovascular disease in older Canadians. The Canadian Heart Health Surveys database provides information about this population upon which health policy related to cardiovascular disease can be based. This paper presents for the first time population-based data on the risk factors for cardiovascular disease in older Canadians. METHODS: Canadians from all 10 provinces participated in surveys of cardiovascular risk factors; health insurance registries were used as sampling frames. In each province, probability samples of 2200 adults 18 to 74 years old not living in institutions, on reserves or in military camps were asked to participate in interviews and to undergo testing at clinics for major risk factors for cardiovascular disease. RESULTS: A total of 2739 men (response rate 70%) and 2617 women (response rate 66%) aged 55 to 74 years participated in the survey and also provided follow-up clinical measurements at the clinic. Overall, 52% of participants were hypertensive, 26% had isolated systolic hypertension, and 30% had a total blood cholesterol level of 6.2 mmol/L or greater. Rates of current smoking were lower in women than men (17% v. 22%). Overall, 87% of men and 78% of women who were current smokers smoked at least 10 cigarettes per day. Only slightly more than half of participants exercised at least once a week for at least 15 minutes, and almost half had a body mass index of 27 or greater. In only 4% was no major risk factor for cardiovascular disease detected. INTERPRETATION: Significant numbers of older Canadians have one or more major risk factors for cardiovascular disease. Many of these risk factors are amenable to modification. 相似文献