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排序方式: 共有221条查询结果,搜索用时 31 毫秒
41.
Teemu Smura Soile Blomqvist Tytti Vuorinen Olga Ivanova Elena Samoilovich Haider Al-Hello Carita Savolainen-Kopra Tapani Hovi Merja Roivainen 《PloS one》2014,9(4)
Genus Enterovirus (Family Picornaviridae,) consists of twelve species divided into genetically diverse types by their capsid protein VP1 coding sequences. Each enterovirus type can further be divided into intra-typic sub-clusters (genotypes). The aim of this study was to elucidate what leads to the emergence of novel enterovirus clades (types and genotypes). An evolutionary analysis was conducted for a sub-group of Enterovirus C species that contains types Coxsackievirus A21 (CVA-21), CVA-24, Enterovirus C95 (EV-C95), EV-C96 and EV-C99. VP1 gene datasets were collected and analysed to infer the phylogeny, rate of evolution, nucleotide and amino acid substitution patterns and signs of selection. In VP1 coding gene, high intra-typic sequence diversities and robust grouping into distinct genotypes within each type were detected. Within each type the majority of nucleotide substitutions were synonymous and the non-synonymous substitutions tended to cluster in distinct highly polymorphic sites. Signs of positive selection were detected in some of these highly polymorphic sites, while strong negative selection was indicated in most of the codons. Despite robust clustering to intra-typic genotypes, only few genotype-specific ‘signature’ amino acids were detected. In contrast, when different enterovirus types were compared, there was a clear tendency towards fixation of type-specific ‘signature’ amino acids. The results suggest that permanent fixation of type-specific amino acids is a hallmark associated with evolution of different enterovirus types, whereas neutral evolution and/or (frequency-dependent) positive selection in few highly polymorphic amino acid sites are the dominant forms of evolution when strains within an enterovirus type are compared. 相似文献
42.
Teemu Kuosmanen Johannes Cairns Robert Noble Niko Beerenwinkel Tommi Mononen Ville Mustonen 《PLoS computational biology》2021,17(9)
Increasing body of experimental evidence suggests that anticancer and antimicrobial therapies may themselves promote the acquisition of drug resistance by increasing mutability. The successful control of evolving populations requires that such biological costs of control are identified, quantified and included to the evolutionarily informed treatment protocol. Here we identify, characterise and exploit a trade-off between decreasing the target population size and generating a surplus of treatment-induced rescue mutations. We show that the probability of cure is maximized at an intermediate dosage, below the drug concentration yielding maximal population decay, suggesting that treatment outcomes may in some cases be substantially improved by less aggressive treatment strategies. We also provide a general analytical relationship that implicitly links growth rate, pharmacodynamics and dose-dependent mutation rate to an optimal control law. Our results highlight the important, but often neglected, role of fundamental eco-evolutionary costs of control. These costs can often lead to situations, where decreasing the cumulative drug dosage may be preferable even when the objective of the treatment is elimination, and not containment. Taken together, our results thus add to the ongoing criticism of the standard practice of administering aggressive, high-dose therapies and motivate further experimental and clinical investigation of the mutagenicity and other hidden collateral costs of therapies. 相似文献
43.
Non-Cholesterol Sterol Levels Predict Hyperglycemia and Conversion to Type 2 Diabetes in Finnish Men
Henna Cederberg Helena Gylling Tatu A. Miettinen Jussi Paananen Jagadish Vangipurapu Jussi Pihlajam?ki Teemu Kuulasmaa Alena Stan?áková Ulf Smith Johanna Kuusisto Markku Laakso 《PloS one》2013,8(6)
We investigated the levels of non-cholesterol sterols as predictors for the development of hyperglycemia (an increase in the glucose area under the curve in an oral glucose tolerance test) and incident type 2 diabetes in a 5-year follow-up study of a population-based cohort of Finnish men (METSIM Study, N = 1,050) having non-cholesterol sterols measured at baseline. Additionally we determined the association of 538,265 single nucleotide polymorphisms (SNP) with non-cholesterol sterol levels in a cross-sectional cohort of non-diabetic offspring of type 2 diabetes (the Kuopio cohort of the EUGENE2 Study, N = 273). We found that in a cross-sectional METSIM Study the levels of sterols indicating cholesterol absorption were reduced as a function of increasing fasting glucose levels, whereas the levels of sterols indicating cholesterol synthesis were increased as a function of increasing 2-hour glucose levels. A cholesterol synthesis marker desmosterol significantly predicted an increase, and two absorption markers (campesterol and avenasterol) a decrease in the risk of hyperglycemia and incident type 2 diabetes in a 5-year follow-up of the METSIM cohort, mainly attributable to insulin sensitivity. A SNP of ABCG8 was associated with fasting plasma glucose levels in a cross-sectional study but did not predict hyperglycemia or incident type 2 diabetes. In conclusion, the levels of some, but not all non-cholesterol sterols are markers of the worsening of hyperglycemia and type 2 diabetes. 相似文献
44.
Erkki Truve Lenne Nigul Teemu H. Teeri Merike Kelve 《Nucleosides, nucleotides & nucleic acids》2013,32(5):1097-1111
Abstract Nonphosphorylated 2-5A inhibited translation and caused RNA degradation in wheat germ extract, whereas 3-5A had no effect. Protein synthesis inhibition by 2-5A was observed in tobacco protoplasts. 70 kD 2-5A-binding protein was found in potato leaf extracts by chemical crosslinking. 相似文献
45.
Anna Lintunen Stefan Mayr Yann Salmon Hervé Cochard Teemu Hölttä 《Ecology and evolution》2018,8(1):333-343
It is not well understood what determines the degree of supercooling of apoplastic sap in trees, although it determines the number and duration of annual freeze–thaw cycles in a given environment. We studied the linkage between apoplastic ice nucleation temperature, tree water status, and conduit size. We used branches of 10 gymnosperms and 16 angiosperms collected from an arboretum in Helsinki (Finland) in winter and spring. Branches with lower relative water content froze at lower temperatures, and branch water content was lower in winter than in spring. A bench drying experiment with Picea abies confirmed that decreasing branch water potential decreases apoplastic ice nucleation temperature. The studied angiosperms froze on average 2.0 and 1.8°C closer to zero Celsius than the studied gymnosperms during winter and spring, respectively. This was caused by higher relative water content in angiosperms; when branches were saturated with water, apoplastic ice nucleation temperature of gymnosperms increased to slightly higher temperature than that of angiosperms. Apoplastic ice nucleation temperature in sampled branches was positively correlated with xylem conduit diameter as shown before, but saturating the branches removed the correlation. Decrease in ice nucleation temperature decreased the duration of freezing, which could have an effect on winter embolism formation via the time available for gas escape during ice propagation. The apoplastic ice nucleation temperature varied not only between branches but also within a branch between consecutive freeze–thaw cycles demonstrating the stochastic nature of ice nucleation. 相似文献
46.
Paula Elomaa Yrjö Helariutta Mika Kotilainen Teemu H. Teeri Robert J. Griesbach Pauli Seppänen 《Molecular & general genetics : MGG》1995,248(6):649-656
Petunia mutant RL01 was transformed with maizeA1 and gerberagdfr cDNAs, which both encode dihydroflavonol-4-reductase (DFR) activity. The sameAgrobacterium vector and the same version of the CaMV 35S promoter were used in both experiments. Transformation with the cDNAs resulted in production of pelargonidin pigments in the transformants. However, theA1 andgdfr transformants showed clearly different phenotypes. The flowers of the primaryA1 transformants were pale and showed variability in pigmentation during their growth, while the flowers of thegdfr transformants showed intense and highly stable coloration. The color difference in the primary transformants was reflected in the expression levels of the transgenes as well as in the levels of anthocyanin pigment. As previously reported by others, the instability in pigmentation in theA1 transformants was more often detected in clones with multiple copies of the transgene and was associated with methylation of the 35S promoter and of the transgene cDNA itself. In thegdfr transformants, the most intense pigmentation was observed in plants with multiple transgenes in their genome. Only rarely was partial methylation of the 35S promoter detected, while thegdfr cDNA always remained in an unmethylated state. We conclude that the properties of the transgene itself strongly influence the inactivation process. The dicotyledonousgdfr cDNA with a lower GC content and fewer possible methylation sites is more compatible the genomic organization of petunia and this prevents it being recognized as a foreign gene and hence silenced by methylation. 相似文献
47.
Luca Bragazza Juul Limpens† Renato Gerdol Philippe Grosvernier‡ Michal Hájek§ Tomá Hájek¶ Petra Hajkova§ Ina Hansen Paola Iacumin Lado Kutnar†† Håkan Rydin‡‡ Teemu Tahvanainen§§ 《Global Change Biology》2005,11(1):106-114
Alteration of the global nitrogen (N) cycle because of human‐enhanced N fixation is a major concern particularly for those ecosystems that are nutrient poor by nature. Because Sphagnum‐dominated mires are exclusively fed by wet and dry atmospheric deposition, they are assumed to be very sensitive to increased atmospheric N input. We assessed the consequences of increased atmospheric N deposition on total N concentration, N retention ability, and δ15N isotopic signature of Sphagnum plants collected in 16 ombrotrophic mires across 11 European countries. The mires spanned a gradient of atmospheric N deposition from about 0.1 up to about 2 g m?2 yr?1. Mean N concentration in Sphagnum capitula was about 6 mg g?1 in less polluted mires and about 13 mg g?1 in highly N‐polluted mires. The relative difference in N concentration between capitulum and stem decreased with increasing atmospheric N deposition, suggesting a possible metabolic mechanism that reduces excessive N accumulation in the capitulum. Sphagnum plants showed lower rates of N absorption under increasing atmospheric N deposition, indicating N saturation in Sphagnum tissues. The latter probably is related to a shift from N‐limited conditions to limitation by other nutrients. The capacity of the Sphagnum layer to filter atmospheric N deposition decreased exponentially along the depositional gradient resulting in enrichment of the mire pore water with inorganic N forms (i.e., NO3?+NH4+). Sphagnum plants had δ15N signatures ranging from about ?8‰ to about ?3‰. The isotopic signatures were rather related to the ratio of reduced to oxidized N forms in atmospheric deposition than to total amount of atmospheric N deposition, indicating that δ15N signature of Sphagnum plants can be used as an integrated measure of δ15N signature of atmospheric precipitation. Indeed, mires located in areas characterized by greater emissions of NH3 (i.e., mainly affected by agricultural activities) had Sphagnum plants with a lower δ15N signature compared with mires located in areas dominated by NOx emissions (i.e., mainly affected by industrial activities). 相似文献
48.
Yrjö Helariutta Mika Kotilainen Paula Elomaa Teemu H. Teeri 《Plant molecular biology》1995,28(5):935-941
In the ornamental cut flower plant Gerbera hybrida the spatial distribution of regulatory molecules characteristic of differentiation of the composite inflorescence is visualized as the various patterns of anthocyanin pigmentation of different varieties. In order to identify genes that the plant can regulate according to these anatomical patterns, we have analysed gene expression affecting two enzymatic steps, chalcone synthase (CHS) and dihydroflavonol-4-reductase (DFR), in five gerbera varieties with spatially restricted anthocyanin pigmentation patterns. The dfr expression profiles vary at the levels of floral organ, flower type and region within corolla during inflorescence development according to the anthocyanin pigmentation of the cultivars. In contrast, chs expression, although regulated in a tissue-specific manner during inflorescence development, varies only occasionally. The variation in the dfr expression profiles between the varieties reveals spatially specific gene regulation that senses the differentiation events characteristic of the composite inflorescence. 相似文献
49.
E. Vartiainen C. Sarti J. Tuomilehto K. Kuulasmaa 《BMJ (Clinical research ed.)》1995,310(6984):901-904
OBJECTIVES--To estimate the extent to which the changes in the main cardiovascular risk factors (blood pressure, smoking, and serum cholesterol concentration) can explain the observed changes in mortality from stroke in Finland during the past 20 years. DESIGN--Predicted changes in mortality from cerebrovascular disease mortality were calculated by a proportional hazards model from data obtained in cross sectional population surveys in 1972, 1977, 1982, 1987, and 1992. Predicted changes were compared with the observed changes in mortality statistics. SETTING--North Karelia and Kuopio provinces, Finland. SUBJECTS--16,741 men and 16,389 women aged 30-59 randomly selected from the national population register, of whom 14,054 men and 14,546 women participated. MAIN OUTCOME MEASURES--Levels of risk factors and predicted and observed changes in mortality from cerebrovascular disease. RESULTS--The observed changes in diastolic blood pressure, total serum cholesterol concentration, and smoking in the population from 1972 to 1992 predicted a 44% fall in mortality from stroke in men and changes in diastolic blood pressure and smoking predicted a 34% fall in women. The observed fall in mortality from stroke was 66% in men and 60% in women. CONCLUSIONS--Two thirds of the fall in mortality from stroke in men and half in women can be explained by changes in the three main cardiovascular risk factors. 相似文献
50.
Granlund Lars Vesakoski Ville Sallinen Antti Kolari Tiina H. M. Wolff Franziska Tahvanainen Teemu 《Ecosystems》2022,25(7):1455-1475
Ecosystems - We investigated recent changes in spatial patterning of fen and bog zones in five boreal aapa mire complexes (mixed peatlands with patterned fen and bog parts) in a multiproxy study.... 相似文献