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741.
Mikhail V. Kozlov Mark D. Hunter Seppo Koponen Jari Kouki Pekka Niemelä Peter W. Price 《Population Ecology》2010,52(2):295-305
Records of 232 moth species spanning 26 years (total catch of ca. 230,000 specimens), obtained by continuous light-trapping
in Kevo, northernmost subarctic Finland, were used to examine the hypothesis that life-history traits and taxonomic position
contribute to both relative abundance and temporal variability of Lepidoptera. Species with detritophagous or moss-feeding
larvae, species hibernating in the larval stage, and species pupating during the first half of the growing season were over-represented
among 42 species classified as abundant during the entire sampling period. The coefficients of variation in annual catches
of species hibernating as eggs averaged 1.7 times higher than those of species hibernating as larvae or pupae. Time-series
analysis demonstrated that periodicity in fluctuations of annual catches is generally independent of life-history traits and
taxonomic affinities of the species. Moreover, closely related species with similar life-history traits often show different
population dynamics, undermining the phylogenetic constraints hypothesis. Species with the shortest (1 year) time lag in the
action of negative feedback processes on population growth exhibit the largest magnitude of fluctuations. Our analyses revealed
that only a few consistent patterns in the population dynamics of herbivorous moths can be deduced from life-history characteristics
of the species. Moreover, the diversity of population behaviour in one moth assemblage challenges any conventional wisdom
suggesting predictable patterns. Our results raise several questions about perceptions and paradigms in insect population
dynamics and stress the need for research on detritivorous insect population dynamics, as well as the need for more assemblage-wide
studies using common trapping methods to provide comparative data on related and unrelated species with different life-history
traits. 相似文献
742.
von Ossowski I Oksanen E von Ossowski L Cai C Sundberg M Goldman A Keinänen K 《The FEBS journal》2006,273(22):5219-5229
Synaptic targeting of GluR-A subunit-containing glutamate receptors involves an interaction with synapse-associated protein 97 (SAP97). The C-terminus of GluR-A, which contains a class I PDZ ligand motif (-x-Ser/Thr-x-phi-COOH where phi is an aliphatic amino acid) associates preferentially with the second PDZ domain of SAP97 (SAP97(PDZ2)). To understand the structural basis of this interaction, we have determined the crystal structures of wild-type and a SAP97(PDZ2) variant in complex with an 18-mer C-terminal peptide (residues 890-907) of GluR-A and of two variant PDZ2 domains in unliganded state at 1.8-2.44 A resolutions. SAP97(PDZ2) folds to a compact globular domain comprising six beta-strands and two alpha-helices, a typical architecture for PDZ domains. In the structure of the peptide complex, only the last four C-terminal residues of the GluR-A are visible, and align as an antiparallel beta-strand in the binding groove of SAP97(PDZ2). The free carboxylate group and the aliphatic side chain of the C-terminal leucine (Leu907), and the hydroxyl group of Thr905 of the GluR-A peptide are engaged in essential class I PDZ interactions. Comparison between the free and complexed structures reveals conformational changes which take place upon peptide binding. The betaAlpha-betaBeta loop moves away from the C-terminal end of alphaB leading to a slight opening of the binding groove, which may better accommodate the peptide ligand. The two conformational states are stabilized by alternative hydrogen bond and coulombic interactions of Lys324 in betaAlpha-betaBeta loop with Asp396 or Thr394 in betaBeta. Results of in vitro binding and immunoprecipitation experiments using a PDZ motif-destroying L907A mutation as well as the insertion of an extra alanine residue between the C-terminal Leu907 and the stop codon are also consistent with a 'classical' type I PDZ interaction between SAP97 and GluR-A C-terminus. 相似文献
743.
Bichlmaier I Siiskonen A Kurkela M Finel M Yli-Kauhaluoma J 《Biological chemistry》2006,387(4):407-416
The stereoselective binding and transformation of optically pure bicyclic alcohols by human UDP-glucuronosyltransferases from subfamily 2B were investigated. The enantiomers of 1-indanol, 1-tetralol, and 1-benzosuberol were synthesized by asymmetric Corey-Bakshi-Shibata reduction and subjected to glucuronidation assays. The alcohols studied were primarily glucuronidated by UGT2B7 and UGT2B17. The catalytic transformation by UGT2B17 was highly stereoselective, favoring conjugation of the (R)-enantiomers. UGT2B7, on the other hand, did not exhibit stereoselectivity toward 1-benzosuberol, the best substrate in this series. To assess binding affinities to the enzymes, the six different compounds were tested for their efficiency as inhibitors of either UGT2B7 or UGT2B17. The results of the latter analyses indicated that the affinities of both enantiomers of each pair towards UGT2B7 and UGT2B17 were of the same order of magnitude. Therefore, the findings of this study suggest that the spatial arrangement of the hydroxy group plays an important role in the glucuronic acid transfer reaction, but not necessarily in substrate binding to the UGTs. 相似文献
744.
Alm R Johansson P Hjernø K Emanuelsson C Ringnér M Häkkinen J 《Journal of proteome research》2006,5(4):785-792
We describe an approach to screen large sets of MALDI-MS mass spectra for protein isoforms separated on two-dimensional electrophoresis gels. Mass spectra are matched against each other by utilizing extracted peak mass lists and hierarchical clustering. The output is presented as dendrograms in which protein isoforms cluster together. Clustering could be applied to mass spectra from different sample sets, dates, and instruments, revealed similarities between mass spectra, and was a useful tool to highlight peptide peaks of interest for further investigation. Shared peak masses in a cluster could be identified and were used to create novel peak mass lists suitable for protein identification using peptide mass fingerprinting. Complex mass spectra consisting of more than one protein were deconvoluted using information from other mass spectra in the same cluster. The number of peptide peaks shared between mass spectra in a cluster was typically found to be larger than the number of peaks that matched to calculated peak masses in databases, thus modified peaks are probably among the shared peptides. Clustering increased the number of peaks associated with a given protein. 相似文献
745.
Plant phenological data and tree-rings were tested for their palaeoclimatic value in south-west Finland since AD 1750. The information from fragmentary, partly overlapping, partly non-systematically biased plant phenological records of 14 different phenomena (a total of 3,144 observations) was combined into one continuous time series of phenological indices. All site- and phenomenon-specific series were standardized to present an average of zero and standard deviation of one. The mean phenomenon-specific series were then averaged as arithmetic means for annually resolved time series representing the variability in the particular plant phenomenon. Consequently, each phenomenon-specific mean series was based on spatially normalized site-specific index series. These series were compared to each other, living-tree and subfossil tree-rings, and to early and modern meteorological time series. Phenological indices showed strong positive correlation with February to June temperatures. On the other hand, the correlations between phenological indices and precipitation data were around zero. Analysis using time-dependent running correlations showed non-stationary relationship between the tree-rings and phenological indices and observed spring temperatures. The skill of phenological data for reconstructing the spring temperatures was statistically proved. 相似文献
746.
Hekim C Leinonen J Närvänen A Koistinen H Zhu L Koivunen E Väisänen V Stenman UH 《The Journal of biological chemistry》2006,281(18):12555-12560
Human kallikrein 2 (hK2) is a serine protease produced by the secretory epithelial cells in the prostate. Because hK2 activates several factors participating in proteolytic cascades that may mediate metastasis of prostate cancer, modulation of the activity of hK2 is a potential way of preventing tumor growth and metastasis. Furthermore, specific ligands for hK2 are potentially useful for targeting and imaging of prostate cancer and for assay development. We have used enzymatically active recombinant hK2 captured by a monoclonal antibody exposing the active site of the enzyme to screen phage display peptide libraries. Using libraries expressing 10 or 11 amino acids long linear peptides, we identified six different peptides binding to hK2. Three of these were shown to be specific and efficient inhibitors of the enzymatic activity of hK2 toward a peptide substrate. Furthermore, the peptides inhibited the activation of the proform of prostate-specific antigen by hK2. Amino acid substitution analyses revealed that motifs of six amino acids were required for the inhibitory activity. These peptides are potentially useful for treatment and targeting of prostate cancer. 相似文献
747.
Background
Microarray technology has become popular for gene expression profiling, and many analysis tools have been developed for data interpretation. Most of these tools require complete data, but measurement values are often missing A way to overcome the problem of incomplete data is to impute the missing data before analysis. Many imputation methods have been suggested, some na?ve and other more sophisticated taking into account correlation in data. However, these methods are binary in the sense that each spot is considered either missing or present. Hence, they are depending on a cutoff separating poor spots from good spots. We suggest a different approach in which a continuous spot quality weight is built into the imputation methods, allowing for smooth imputations of all spots to larger or lesser degree. 相似文献748.
Tuomo Nieminen Rami Lehtinen Jari Viik Terho Lehtimäki Kari Niemelä Kjell Nikus Mari Niemi Janne Kallio Tiit Kööbi Väinö Turjanmaa Mika Kähönen 《BMC cardiovascular disorders》2006,6(1):1-8
Background
The occurrence of variations in the spectrum of cardiovascular disease between different regions of the world and ethnic groups have been the subject of great interest. This study report the 24-h variation of myocardial infarction (MI) occurrence in patients recruited from CCU located in Argentina and Uruguay.Methods
A cohort of 1063 patients admitted to the CCU within 24 h of the onset of symptoms of an acute MI was examined. MI incidence along the day was computed in 1 h-intervals.Results
A minimal MI incidence between 03:00 and 07:00 h and the occurrence of a first maximum between 08:00 and 12:00 h and a second maximum between 15:00 and 22:00 h were verified. The best fit curve was a 24 h cosinor (acrophase ~ 19:00 h, accounting for 63 % of variance) together with a symmetrical gaussian bell (maximum at ~ 10:00 h, accounting for 37 % of variance). A similar picture was observed for MI frequencies among different excluding subgroups (older or younger than 70 years; with or without previous symptoms; diabetics or non diabetics; Q wave- or non-Q wave-type MI; anterior or inferior MI location). Proportion between cosinor and gaussian probabilities was maintained among most subgroups except for older patients who had more MI at the afternoon and patients with previous symptoms who were equally distributed among the morning and afternoon maxima.Conclusion
The results support the existence of two maxima (at morning and afternoon hours) in MI incidence in the Argentine and Uruguayan population. 相似文献749.
750.
Habitat selection of coexisting competitors: a study of small mustelids in northern Norway 总被引:1,自引:1,他引:0
The coexistence of two very similar species, stoat and least weasel, has puzzled many researchers. From their ecology it is expected that they do not coexist, not locally at least, and still they seem to do. We reviewed the specific hypotheses proposed to explain their coexistence and related these to general theories of competitive coexistence. To test these conjectures, we studied the habitat selection of least weasels and stoats on landscape and on local scale. The study was performed during the winters, the most critical season, in years 1986–2001 in northern Norway. Stoats were usually more numerous than least weasels. Stoats showed preference for productive areas both at the landscape and at the habitat scale and appeared stereotypic in their habitat selection. Least weasels were more generalized and flexible in their habitat selection. Contrary to results reported in many studies, least weasel did not react to the presence of stoats and were not excluded from the areas with stoats. We suggest that in the conditions of northernmost Fennoscandia, the two species exhibit a variant of classical competitive coexistence. Both species have a shared preference for rodents, but the access to exclusive alternative prey in stoats allows their coexistence with least weasels, which are more efficient predators on rodents. We suggest that more attention should be paid on survival resources, exploited during times of low resource density, when studying the coexistence between close competitors. 相似文献