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81.
Liisa Kautto Jasmine Grinyer Debra Birch Amit Kapur Mark Baker Mathew Traini Peter Bergquist Helena Nevalainen 《Protein expression and purification》2009,67(2):156-163
We have developed a fast and simple two column chromatographic method for the purification of the 26S proteasome from the filamentous fungus Trichoderma reesei that simplifies the overall procedure and reduces the purification time from 5 to 2.5 days. The combination of only the anionic exchange POROS® HQ column (Applied Biosystems) together with a size exclusion column has not been used previously for proteasome purification. The purified complex was analysed further by two-dimensional electrophoresis (2DE) and examined by transmission electron microscopy (TEM). A total of 102 spots separated by 2DE were identified by mass spectrometry using cross-species identification (CSI) or an in-house custom-made protein database derived from the T. reesei sequencing project. Fifty-one spots out of 102 represented unique proteins. Among them, 30 were from the 20S particle and eight were from the 19S particle. In addition, seven proteasome-interacting proteins as well as several non-proteasome related proteins were identified. Co-purification of the 19S regulatory particle was confirmed by TEM and Western blotting. The rapidity of the purification procedure and largely intact nature of the complex suggest that similar procedure may be applicable to the isolation and purification of the other protein complexes. 相似文献
82.
Teija Ruuhola Liisa M. Rantala Seppo Neuvonen Shiyong Yang Markus J. Rantala 《Basic and Applied Ecology》2009,10(7):589-596
Anthropogenic pollution causes oxidative stress in plants and reactive oxygen species (ROS) are diminished by antioxidative enzymes and small molecular antioxidants. Pollution may also affect the performance of plant-eating animals by increasing or decreasing their performance. The effects of pollution cannot be fully understood without knowledge of how pollution affects the interactions with the third trophic level, namely natural enemies and diseases of herbivores. In this study, we examined how long-term (19 yr) acid rain pollution affects (i) the oxidative responses in mountain birch foliage and (ii) the growth and immune responses of autumnal moth larvae. We found that pollution caused a 50% increase (p<0.05) in the peroxidase activities (PODs) in birch leaves whereas polyphenoloxidase (PPO) or catalase (CAT) activities were not affected, suggesting that PODs play an important role in the quenching of the oxidative stress in birches. In polluted trees, phenoloxidases probably acted as antioxidative not prooxidative enzymes, which was shown as positive relations between enzyme activities (PPO, CAT) and larval performance (pupal weights). Although acid rain pollution did not have any direct effect on either pupal weight or the length of larval period, the stronger acid rain treatment reduced slightly (6% in females) the encapsulation response of pupae. A decrease of this magnitude might be too small to have measurable effects on the incidence of moth outbreaks. 相似文献
83.
84.
Lagerspetz KY Vainio LA 《Biological reviews of the Cambridge Philosophical Society》2006,81(2):237-258
Specific thermoreceptors or putative multimodal thermoreceptors are not known in Crustacea. However, behavioural studies on thermal avoidance and preference and on the effects of temperature on motor activity indicate that the thermosensitivity of crustaceans may be in the range 0.2-2 degrees C. Work on planktonic crustaceans suggests that they respond particularly to changes in temperature by klinokinesis and orthokinesis. The thermal behaviour of crustaceans is modified by thermal acclimation among other factors. The acclimation of the critical maximum temperature is an example of resistance acclimation, while the acclimation of preference behaviour may be classified as capacity acclimation of some other function. In crustaceans, the use of the concepts stenothermy and eurythermy at the species level is questionable, and it is not possible to divide crustacean species into thermal guilds as suggested for fishes. Thermal preference behaviour contributes to fitness in different ways in different species, often by maximising the aerobic metabolic scope for activity. In crustaceans the peripheral nervous system seems to have retained the capacity for thermosensitivity and thermal acclimation independently of the central nervous system control of behaviour. 相似文献
85.
Liisa Huttunen Pekka Niemelä Vladimir Ossipov Matti Rousi Tero Klemola 《Trees - Structure and Function》2012,26(3):809-819
Subarctic mountain birch (Betula pubescens ssp. czerepanovii) forests in northern Fennoscandia have shown a slight recovery from recent severe defoliation by the winter moth (Operophtera brumata). This development in trees is hypothesized to be a result of ameliorated growing conditions through increased summer temperatures.
We examined if accumulated thermal sum affects the ability of mountain birches to tolerate foliage losses. We quantified the
number of leaf-bearing short shoots, the emergence of inflorescences and the seasonal height growth of long shoots in both
intact and defoliated trees. We also determined the concentrations of carbon and nitrogen in leaves and carbohydrates in roots.
Our results show that defoliation constrained the growth of long shoots, as well as the emergence of inflorescences regardless
of thermal sum accumulation. However, the number of leaf-bearing short shoots did not differ between intact and defoliated
trees. In the both tree groups, the amounts of emerging leaves increased as a response to thermal sum accumulation. Also the
leaf carbon concentration increased in defoliated trees at higher thermal sums, whereas it decreased in intact controls. Generally,
the mean carbohydrate concentrations were greater in roots of defoliated than intact trees. However, with increased thermal
sums, root carbohydrates increased in intact trees but remained the same in defoliated trees. We conclude that thermal sum
accumulation does not greatly promote the recovery of mountain birches. Although the damaged trees produced more leaves at
warmer growing sites, this did not increase their height growth or carbohydrate gain in roots. 相似文献
86.
Kristina Laaksonen Liisa Helle Lauri Parkkonen Erika Kirveskari Jyrki P. M?kel? Satu Mustanoja Turgut Tatlisumak Markku Kaste Nina Forss 《PloS one》2013,8(4)
Amplitude or frequency alterations of spontaneous brain oscillations may reveal pathological phenomena in the brain or predict recovery from brain lesions, but the temporal evolution and the functional significance of these changes is not well known. We performed follow-up recordings of spontaneous brain oscillations with whole-head MEG in 16 patients with first-ever stroke in the middle cerebral artery territory, affecting upper limb motor function, 1–7 days (T0), 1 month (T1), and 3 months (T2) after stroke, with concomitant clinical examination. Clinical test results improved significantly from T0 to T1 or T2. During recovery (at T1 and T2), the strength of temporo–parietal ∼10-Hz oscillations in the affected hemisphere (AH) was increased as compared with the unaffected hemisphere. Abnormal low-frequency magnetic activity (ALFMA) at ∼1 Hz in the AH was detected in the perilesional cortex in seven patients at T0. In four of these, ALFMA persisted at T2. In patients with ALFMA, the lesion size was significantly larger than in the rest of the patients, and worse clinical outcome was observed in patients with persisting ALFMA. Our results indicate that temporo–parietal ∼10-Hz oscillations are enhanced in the AH during recovery from stroke. Moreover, stroke causes ALFMA, which seems to persist in patients with worse clinical outcome. 相似文献
87.
88.
The recent determination of the three-dimensional structure of urease revealed striking similarities of enzyme architecture to adenosine deaminase and phosphotriesterase, evidence of a distant evolutionary relationship that had gone undetected by one-dimensional sequence comparisons. Here, based on an analysis of conservation patterns in three dimensions, we report the discovery of the same active-site architecture in an even larger set of enzymes involved primarily in nucleotide metabolism. As a consequence, we predict the three-dimensional fold and details of the active site architecture for dihydroorotases, allantoinases, hydantoinases, AMP-, adenine and cytosine deaminases, imidazolonepropionase, aryldialkylphosphatase, chlorohydrolases, formylmethanofuran dehydrogenases, and proteins involved in animal neuronal development. Two member families are common to archaea, eubacteria, and eukaryota. Thirteen other functions supported by the same structural motif and conserved chemical mechanism apparently represent later adaptations for different substrate specificities in different cellular contexts. © 1997 Wiley-Liss Inc. 相似文献
89.
The action of berry phenolics against human intestinal pathogens 总被引:1,自引:0,他引:1
Puupponen-Pimiä R Nohynek L Alakomi HL Oksman-Caldentey KM 《BioFactors (Oxford, England)》2005,23(4):243-251
Phenolic compounds present in berries selectively inhibit the growth of human gastrointestinal pathogens. Especially cranberry, cloudberry, raspberry, strawberry and bilberry possess clear antimicrobial effects against e.g. salmonella and staphylococcus. Complex phenolic polymers, such as ellagitannins, are strong antibacterial agents present in cloudberry, raspberry and strawberry. Berry phenolics seem to affect the growth of different bacterial species with different mechanisms. Adherence of bacteria to epithelial surfaces is a prerequisite for colonization and infection of many pathogens. Antimicrobial activity of berries may also be related to anti-adherence activity of the berries. Utilization of enzymes in berry processing increases the amount of phenolics and antimicrobial activity of the berry products. Antimicrobial berry compounds are likely to have many important applications in the future as natural antimicrobial agents for food industry as well as for medicine. 相似文献
90.
Little is currently known about the substrate binding site of the human UDP-glucuronosyltransferases (UGTs) and the structural elements that affect their complex substrate selectivity. In order to further understand and extend our earlier findings with phenylalanines 90 and 93 of UGT1A10, we have replaced each of them with Gly, Ala, Val, Leu, Ile or Tyr, and tested the activity of the resulting 12 mutants toward eight different substrates. Apart from scopoletin glucuronidation, the F90 mutants other than F90L were nearly inactive, while the F93 mutants’ activity was strongly substrate dependent. Hence, F93L displayed high entacapone and 1-naphthol glucuronidation rates, whereas F93G, which was nearly inactive in entacapone glucuronidation, was highly active toward estradiol, estriol and even ethinylestradiol, a synthetic estrogen that is a poor substrate for the wild-type UGT1A10. Kinetic analyses of 4-nitrophenol, estradiol and ethinylestradiol glucuronidation by the mutants that catalyzed the respective reactions at considerable rates, revealed increased Km values for 4-nitrophenol and estradiol in all the mutants, whilst the Km values of F93G and F93A for ethinylestradiol were lower than in control UGT1A10. Based on the activity results and a new molecular model of UGT1A10, it is suggested that both F90 and F93 are located in a surface helix at the far end of the substrate binding site. Nevertheless, only F93 directly affects the selectivity of UGT1A10 toward large and rigid estrogens, particularly those with substitutions at the D ring. The effects of F93 mutations on the glucuronidation of smaller or less rigid substrates are indirect, however. 相似文献