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排序方式: 共有910条查询结果,搜索用时 31 毫秒
831.
832.
Shengting Li Annalaura Barbieri Federica Tallaro Laura Lomartire Dario Vianello Alberto Montesanto Jukka S. Moilanen Vladyslav Bezrukov Hélène Blanché Antti Hervonen Kaare Christensen Luca Deiana Efstathios S. Gonos Tom B. L. Kirkwood Peter Kristensen Alberta Leon Pier Giuseppe Pelicci Michel Poulain Irene M. Rea Josè Remacle Jean Marie Robine Stefan Schreiber Ewa Sikora Peternella Eline Slagboom Liana Spazzafumo Maria Antonietta Stazi Olivier Toussaint James W. Vaupel Giuseppina Rose Kari Majamaa Markus Perola Thomas E. Johnson Lars Bolund Huanming Yang Giuseppe Passarino Claudio Franceschi 《Aging cell》2014,13(3):401-407
To re‐examine the correlation between mtDNA variability and longevity, we examined mtDNAs from samples obtained from over 2200 ultranonagenarians (and an equal number of controls) collected within the framework of the GEHA EU project. The samples were categorized by high‐resolution classification, while about 1300 mtDNA molecules (650 ultranonagenarians and an equal number of controls) were completely sequenced. Sequences, unlike standard haplogroup analysis, made possible to evaluate for the first time the cumulative effects of specific, concomitant mtDNA mutations, including those that per se have a low, or very low, impact. In particular, the analysis of the mutations occurring in different OXPHOS complex showed a complex scenario with a different mutation burden in 90+ subjects with respect to controls. These findings suggested that mutations in subunits of the OXPHOS complex I had a beneficial effect on longevity, while the simultaneous presence of mutations in complex I and III (which also occurs in J subhaplogroups involved in LHON) and in complex I and V seemed to be detrimental, likely explaining previous contradictory results. On the whole, our study, which goes beyond haplogroup analysis, suggests that mitochondrial DNA variation does affect human longevity, but its effect is heavily influenced by the interaction between mutations concomitantly occurring on different mtDNA genes. 相似文献
833.
834.
Diego Caballero Jukka Määttä Alice Qinhua Zhou Maria Sammalkorpi Corey S. O'Hern Lynne Regan 《Protein science : a publication of the Protein Society》2014,23(7):970-980
A fundamental question in protein science is what is the intrinsic propensity for an amino acid to be in an α-helix, β-sheet, or other backbone dihedral angle (-ψ) conformation. This question has been hotly debated for many years because including all protein crystal structures from the protein database, increases the probabilities for α-helical structures, while experiments on small peptides observe that β-sheet-like conformations predominate. We perform molecular dynamics (MD) simulations of a hard-sphere model for Ala dipeptide mimetics that includes steric interactions between nonbonded atoms and bond length and angle constraints with the goal of evaluating the role of steric interactions in determining protein backbone conformational preferences. We find four key results. For the hard-sphere MD simulations, we show that (1) β-sheet structures are roughly three and half times more probable than α-helical structures, (2) transitions between α-helix and β-sheet structures only occur when the backbone bond angle τ (N–Cα–C) is greater than 110°, and (3) the probability distribution of τ for Ala conformations in the “bridge” region of-ψ space is shifted to larger angles compared to other regions. In contrast, (4) the distributions obtained from Amber and CHARMM MD simulations in the bridge regions are broader and have increased τ compared to those for hard sphere simulations and from high-resolution protein crystal structures. Our results emphasize the importance of hard-sphere interactions and local stereochemical constraints that yield strong correlations between -ψ conformations and τ. 相似文献
835.
Demographic histories and genetic diversities of Fennoscandian marine and landlocked ringed seal subspecies
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Tommi Nyman Mia Valtonen Jouni Aspi Minna Ruokonen Mervi Kunnasranta Jukka U. Palo 《Ecology and evolution》2014,4(17):3420-3434
Island populations are on average smaller, genetically less diverse, and at a higher risk to go extinct than mainland populations. Low genetic diversity may elevate extinction probability, but the genetic component of the risk can be affected by the mode of diversity loss, which, in turn, is connected to the demographic history of the population. Here, we examined the history of genetic erosion in three Fennoscandian ringed seal subspecies, of which one inhabits the Baltic Sea ‘mainland’ and two the ‘aquatic islands’ composed of Lake Saimaa in Finland and Lake Ladoga in Russia. Both lakes were colonized by marine seals after their formation c. 9500 years ago, but Lake Ladoga is larger and more contiguous than Lake Saimaa. All three populations suffered dramatic declines during the 20th century, but the bottleneck was particularly severe in Lake Saimaa. Data from 17 microsatellite loci and mitochondrial control‐region sequences show that Saimaa ringed seals have lost most of the genetic diversity present in their Baltic ancestors, while the Ladoga population has experienced only minor reductions. Using Approximate Bayesian computing analyses, we show that the genetic uniformity of the Saimaa subspecies derives from an extended founder event and subsequent slow erosion, rather than from the recent bottleneck. This suggests that the population has persisted for nearly 10,000 years despite having low genetic variation. The relatively high diversity of the Ladoga population appears to result from a high number of initial colonizers and a high post‐colonization population size, but possibly also by a shorter isolation period and/or occasional gene flow from the Baltic Sea. 相似文献
836.
A checklist of the families Chaoboridae, Dixidae, Thaumaleidae, Psychodidae and Ptychopteridae (Diptera) recorded from Finland is given. Four species, Dixella
dyari Garret, 1924 (Dixidae), Threticus
tridactilis (Kincaid, 1899), Panimerus
albifacies (Tonnoir, 1919) and Panimerus
przhiboroi Wagner, 2005 (Psychodidae) are reported for the first time from Finland. 相似文献
837.
Tytti Niemelä Tuomas Virén Jukka Liukkonen David Argüelles Nikae C R te Moller Pia H Puhakka Jukka S Jurvelin Riitta-Mari Tulamo Juha Töyräs 《Acta veterinaria Scandinavica》2014,56(1):1-8
Background
Staphylococcus aureus is an important cause of clinical mastitis in dairy cows worldwide. The cure rate after antimicrobial treatment of clinical S. aureus mastitis is very variable due to both cow and bacterial factors. Studies have shown that bacterial genotype might affect short-term bacteriological and clinical cure, but the long-term outcome has been less studied. The objectives of this study were to investigate associations between bacterial genotype and long-term outcome of veterinary-treated clinical mastitis (VTCM) caused by S. aureus during a follow-up period of 120 days and to study genotype variation among Swedish S. aureus isolates. S. aureus isolates from cases of VTCM were genotyped by pulsed-field gel electrophoresis. Long-term outcome measurements used were somatic cell count (SCC), additional diagnoses of VTCM, milk yield and culling. Isolates were classified into clusters (>80% similarity) and pulsotypes (100% similarity). Clusters and pulsotypes were grouped according to occurrence. Multivariable mixed-effect linear regression models including cow and bacterial factors with possible influence on SCC or milk yield were used to calculate differences in SCC or milk yield between groups. Additional outcome measures were calculated using a test of proportions.Results
The isolates (n?=?185) were divided into 18 clusters and 29 pulsotypes. Two pulsotypes were classified as common, and were found in 64% of the cases of VTCM. Remaining isolates were classified as less common or rare pulsotypes. The distribution was similar at cluster level. Outcome was calculated from follow-up data on 111 cows. Significantly lower SCC during the follow-up period was found in cows infected with common clusters compared to in cows infected with less common/rare clusters. The proportion of cows with SCC <200 000 cells/ml during the whole follow-up period was significantly higher in the group common clusters than in the group less common/rare clusters. Bacterial genotype did not influence the other outcome parameters.Conclusions
In Sweden, two S. aureus pulsotypes, identified in about 64% of clinical S. aureus cases, were widespread. Cows infected with the common genotypes had significantly lower SCC during 120 days after treatment compared to cows infected with less common or rare genotypes. 相似文献838.
Yi-Te Lai Jukka Kekäläinen Raine Kortet 《Marine and Freshwater Behaviour and Physiology》2016,49(1):47-61
The influence of trophically transmitted parasite infection on fitness-related locomotor performance in fish as definite hosts has been studied relatively rarely and is thus mostly unknown. In this study, we examined the effect of body cavity dwelling nematode Philometra ovata on the swimming performance, fitness-related traits (male body quality) and male sexual ornamentation of their definitive host, European minnow (Phoxinus phoxinus). Despite the fact that P. ovata is relatively large in body size and thus presumably costly for their host minnows, we found that the abundance of the parasite did not correlate with the swimming performance of the male minnows. Neither did the infection of P. ovata impair the male sexual ornamentation or the male body quality. These partly unexpected results highlight the fact that the P. ovata induced impairment on fitness-related traits of host male minnows is not straightforward, and thus additional physiological studies in infected minnows are needed before final conclusions about the actual harmfulness of the parasite can be made. 相似文献
839.
Turbulence can affect predator–prey interactions. The effect of turbulence on the feeding efficiency of an ambush predator was tested with laboratory experiments. The experiments were conducted in 100-L aquaria in which ten individuals of fourth instar Chaoborus flavicans larvae were placed as predators. Two prey densities (3 and 10 ind. of Daphnia pulex L?1) and two durations (30 and 120 min) were tested in a nonturbulent treatment and five different turbulence levels [average root-mean-square (RMS) velocities ranging from 0 to 7.3 cm s?1, corresponding dissipation rates from 7.2 × 10?7 to 1.3 × 10?3 m2 s?3]. We hypothesized that the feeding rate of C. flavicans would be enhanced by turbulence due to increasing encounter rates up to a turbulence level above which a disturbance in post-encounter processes would lead to reduced feeding efficiency. However, the results showed no significant increase in the feeding rate of C. flavicans at intermediate turbulence. At high turbulence we found the expected significant negative response in the feeding rate of Chaoborus larvae. The feeding rate declined below the rates at nonturbulent and intermediate turbulence conditions as the average RMS velocity exceeded 3.1 cm s?1 (dissipation rate 9.9 × 10?5 m2 s?3, respectively). 相似文献
840.
Helena Tuominen-Gustafsson Markus Penttinen Jukka Hytönen Matti K Viljanen 《BMC microbiology》2006,6(1):92-14