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排序方式: 共有178条查询结果,搜索用时 93 毫秒
51.
The Auxin-Binding Protein 1 (ABP1) was identified over 30 years ago thanks to it''s high affinity for active auxins. ABP1 plays an essential role in plant life yet to this day, its function remains ‘enigmatic.’ A recent study by our laboratory shows that ABP1 is critical for regulation of the cell cycle, acting both in G1 and at the G2/M transition. We showed that ABP1 is likely to mediate the permissive auxin signal for entry into the cell cycle. These data were obtained by studying a conditional functional knock-out of ABP1 generated by cellular immunization in the model tobacco cell line, Bright Yellow 2.Key Words: auxin responses, auxin-binding protein 1, immunomodulation, cellular immunisation 相似文献
52.
Veerman JL Barendregt JJ van Beeck EF Seidell JC Mackenbach JP 《Obesity (Silver Spring, Md.)》2007,15(9):2365-2370
Objective: Obesity is a growing problem worldwide, but there are no good methods to assess the future course of the epidemic and the potential influence of interventions. We explore the behavior change needed to stop the obesity epidemic in the U.S. Research Methods and Procedures: We modeled the population distribution of BMI as a log‐normal curve of which the mean shifts upward with time due to a positive population energy balance. Interventions that decrease food intake or increase physical activity result in more favorable trends in BMI. Results: The recently observed trend in average BMI implies that the average U.S. adult over‐consumes by ~10 kcal/d. If this trend continues unaltered, obesity prevalence will exceed 40% for men and 45% for women in 2015. To stop the epidemic, it suffices to decrease caloric consumption by ~10 kcal or walk an extra 2 to 3 minutes per day, on average. Discussion: This leads to a paradox: little behavior change seems sufficient to halt the epidemic, but in practice this proves hard to achieve. The obesogenic environment is the likely culprit. Individuals trying to maintain a healthy weight need to be supported by environments that stimulate physical activity and do not encourage over‐consumption. Research should show what measures are effective. 相似文献
53.
Jelani T.D. Leito Antoon J.M. Ligtenberg Kamran Nazmi & Enno C.I. Veerman 《FEMS yeast research》2009,9(7):1102-1110
Candida albicans , the major human fungal pathogen, undergoes a reversible morphological transition from single yeast cells to pseudohyphae and hyphae filaments. The hyphae form is considered the most invasive form of the fungus. The purpose of this study is to investigate the effect of saliva on hyphae growth of C. albicans. Candida albicans hyphae were inoculated in Roswell Park Memorial Institute medium with whole saliva, parotid saliva or buffer mimicking the saliva ion composition, and cultured for 18 h at 37 °C under aerobic conditions with 5% CO2 . Whole saliva and parotid saliva induced transition to yeast growth, whereas the culture with buffer remained in the hyphae form. Parotid saliva was fractionated on a reverse-phase C8 column and each fraction was tested for inducing transition to yeast growth. By immunoblotting, the salivary component in the active fraction was identified as statherin, a phosphoprotein of 43 amino acids that has been implicated in remineralization of the teeth. Synthetically made statherin induced transition of hyphae to yeast. By deletion of five amino acids at the negatively charged N-terminal site (DpSpSEE), yeast-inducing activity and binding to C. albicans were increased. In conclusion, statherin induces transition to yeast of C. albicans hyphae and may thus contribute to the oral defense against candidiasis. 相似文献
54.
Background
Fruits and vegetables are an essential part of the human diet, but many people do not consume the recommended serves to prevent cardiovascular disease and cancer. In this research, we evaluate the cost-effectiveness of interventions to promote fruit and vegetable consumption to determine which interventions are good value for money, and by how much current strategies can reduce the population disease burden.Methods/Principal Findings
In a review of published literature, we identified 23 interventions for promoting fruit and vegetable intake in the healthy adult population that have sufficient evidence for cost-effectiveness analysis. For each intervention, we model the health impacts in disability-adjusted life years (DALYs), the costs of intervention and the potential cost-savings from averting disease treatment, to determine cost-effectiveness of each intervention over the lifetime of the population, from an Australian health sector perspective. Interventions that rely on dietary counselling, telephone contact, worksite promotion or other methods to encourage change in dietary behaviour are not highly effective or cost-effective. Only five out of 23 interventions are less than an A$50,000 per disability-adjusted life year cost-effectiveness threshold, and even the most effective intervention can avert only 5% of the disease burden attributed to insufficient fruit and vegetable intake.Conclusions/Significance
We recommend more investment in evaluating interventions that address the whole population, such as changing policies influencing price or availability of fruits and vegetables, to see if these approaches can provide more effective and cost-effective incentives for improving fruit and vegetable intake. 相似文献55.
Micro-array analysis of resistance for gemcitabine results in increased expression of ribonucleotide reductase subunits 总被引:5,自引:0,他引:5
Smid K Bergman AM Eijk PP Veerman G van Haperen VW van den Ijssel P Ylstra B Peters GJ 《Nucleosides, nucleotides & nucleic acids》2006,25(9-11):1001-1007
To study in detail the relation between gene expression and resistance against gemcitabine, a cell line was isolated from a tumor for which gemcitabine resistance was induced in vivo. Similar to the in vivo tumor, resistance in this cell line, C 26-G, was not related to deficiency of deoxycytidine kinase (dCK). Micro-array analysis showed increased expression of ribonucleotide reductase (RR) subunits M1 and M2 as confirmed by real time PCR analysis (28- and 2.7-fold, respectively). In cell culture, moderate cross-resistance (about 2-fold) was observed to 1-ss-D-arabinofuranosylcytosine (ara-C), 2-chloro-2'deoxyadenosine (CdA), LY231514 (ALIMTA), and cisplatin (CDDP), and pronounced cross-resistance (>23-fold) to 2',2'-difluorodeoxyuridine (dFdU) and 2',2'-difluorodeoxyguanosine (dFdG). Culture in the absence of gemcitabine reduced resistance as well as RRM1 RNA expression, demonstrating a direct relationship of RRM1 RNA expression with acquired resistance to gemcitabine. 相似文献
56.
Veerman EC van den Keijbus PA Nazmi K Vos W van der Wal JE Bloemena E Bolscher JG Amerongen AV 《Glycobiology》2003,13(5):363-366
Salivary mucins, encoded by the MUC5B gene, make up a heterogeneous family of molecules, which are secreted by several glands, including the submandibular, sublingual, and palatine glands. Previous studies have shown that heterogeneity in the salivary mucin population is related to its multiglandular origin. In the present study we address the question to what extent the mucin (MUC5B) population from a single human salivary gland is made up of different glycoforms. Using monoclonal antibodies to defined protein and sulfated carbohydrate epitopes specific to MUC5B, we conduct an immunohistochemical study of different salivary gland types, including submandibular, sublingual, and labial glands. In all tissues studied we found a mosaic expression pattern of sulfo-Lewis a antigen, recognized by mAb F2, which in salivary glands is exclusively present on MUC5B. On the other hand, mucous acini were uniformly labeled by mAb EU-MUC5Bb, evoked against a peptide-stretch of the tandem repeat region of MUC5B. Double staining with both antibodies confirmed the presence of MUC5B-positive/sulfo-Lewis a-positive cells, as well as MUC5B-positive/sulfo-Lewis a-negative cells within one glandular unit. These results indicate that one and the same salivary gland synthesizes different MUC5B glycoforms. 相似文献
57.
58.
Jasper Groenink Enno C.I. Veerman Myrna S. Zandvoort Henny C. Van der Mei Henk J. Busscher Arie V. Nieuw Amerongen 《Antonie van Leeuwenhoek》1998,73(3):279-288
The adhesion of Actinobacillus actinomycetemcomitans is a virulence factor in the aetiology of periodontitis and is determined by physico-chemical properties, e.g. surface charge and hydrophobicity, of the bacterial cell surface. Although oral surfaces are constantly coated with saliva, few studies have dealt with the binding of A. actinomycetemcomitans with saliva. In this report, the charge properties of A. actinomycetemcomitans have been studied through measurement of the zeta potential and the saliva-bacteria interaction investigated at different pH-values.At physiological conditions the zeta potential was negative, varying from -11 to -26 mV, for two laboratory and two fresh isolates of A. actinomycetemcomitans. Under these conditions, binding of the low-molecular-weight salivary mucin, lactoferrin, and S-IgA was confirmed using salivary samples and purified salivary fractions in liquid-phase and in ELISA. The iso-electric points of the laboratory and fresh clinical isolates of A. actinomycetemcomitans were determined at pH 4.6 and 3.8, respectively. At pH below the iso-electric point, giving positive values of the zeta potential, additional salivary protein species bound to A. actinomycetemcomitans, including the high-molecular-weight salivary mucin (MG1) and agglutinin. Binding of the low-molecular-weight salivary mucin (MG2), lactoferrin, and S-IgA, was hardly affected by this change in zeta potential. A salivary coating formed on the bacterium at pH 7 reduced the zeta potential of the laboratory strain Y4 greatly and an iso-electric point for the bacterium could not be determined. Overall, the study suggests that upon changes in environmental pH additional salivary attachment sites on the micro-organism are exposed. 相似文献
59.
The murid rodent subfamily Sigmodontinae contains 79 genera which are
distributed throughout the New World. The time of arrival of the first
sigmodontines in South America and the estimated divergence time(s) of the
different lineages of South American sigmodontines have been controversial
due to the lack of a good fossil record and the immense number of extant
species. The "early-arrival hypothesis" states that the sigmodontines must
have arrived in South America no later than the early Miocene, at least 20
MYA, in order to account for their vast present-day diversity, whereas the
"late-arrival hypothesis" includes the sigmodontines as part of the
Plio-Pleistocene Great American Interchange, which occurred approximately
3.5 MYA. The phylogenetic relationships among 33 of these genera were
reconstructed using mitochondrial DNA (mtDNA) sequence data from the ND3,
ND4L, arginine tRNA, and ND4 genes, which we show to be evolving at the
same rate. A molecular clock was calibrated for these genes using published
fossil dates, and the genetic distances were estimated from the DNA
sequences in this study. The molecular clock was used to estimate the dates
of the South American sigmodontine origin and the main sigmodontine
radiation in order to evaluate the "early-" and "late-arrival" scenarios.
We estimate the time of the sigmodontine invasion of South America as
between approximately 5 and 9 MYA, supporting neither of the scenarios but
suggesting two possible models in which the invading lineage was either (1)
ancestral to the oryzomyines, akodonts, and phyllotines or (2) ancestral to
the akodonts and phyllotines and accompanied by the oryzomyines. The
sigmodontine invasion of South America provides an example of the advantage
afforded to a lineage by the fortuitous invasion of a previously
unexploited habitat, in this case an entire continent.
相似文献
60.
Multiple duplications of yeast hexose transport genes in response to selection in a glucose-limited environment 总被引:11,自引:2,他引:9
When microbes evolve in a continuous, nutrient-limited environment, natural
selection can be predicted to favor genetic changes that give cells greater
access to limiting substrate. We analyzed a population of baker's yeast
that underwent 450 generations of glucose-limited growth. Relative to the
strain used as the inoculum, the predominant cell type at the end of this
experiment sustains growth at significantly lower steady-state glucose
concentrations and demonstrates markedly enhanced cell yield per mole
glucose, significantly enhanced high-affinity glucose transport, and
greater relative fitness in pairwise competition. These changes are
correlated with increased levels of mRNA hybridizing to probe generated
from the hexose transport locus HXT6. Further analysis of the evolved
strain reveals the existence of multiple tandem duplications involving two
highly similar, high- affinity hexose transport loci, HXT6 and HXT7.
Selection appears to have favored changes that result in the formation of
more than three chimeric genes derived from the upstream promoter of the
HXT7 gene and the coding sequence of HXT6. We propose a genetic mechanism
to account for these changes and speculate as to their adaptive
significance in the context of gene duplication as a common response of
microorganisms to nutrient limitation.
相似文献