| 7541. |
- Jortikka, Matti, et al.
(författare)
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Immobilisation causes longlasting matrix changes both in the immobilised and contralateral joint cartilage.
- 1997
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Ingår i: Annals of the Rheumatic Diseases. - : BMJ. - 0003-4967 .- 1468-2060. ; 56:4, s. 255-261
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The capacity of articular cartilage matrix to recover during 50 weeks of remobilisation after an atrophy caused by 11 weeks of immobilisation of the knee (stifle) joint in 90 degrees flexion starting at the age of 29 weeks, was studied in young beagle dogs.METHODS: Proteoglycan concentration (uronic acid) and synthesis ([35S]sulphate incorporation) were determined in six and three knee joint surface locations, respectively. Proteoglycans extracted from the cartilages were characterised by chemical determinations, gel filtration, and western blotting for chondroitin sulphate epitope 3B3.RESULTS: The proteoglycan concentrations that were reduced in all sample sites immediately after the immobilisation, remained 14-28% lower than controls after 50 weeks of remobilisation in the patella, the summit of medial femoral condyle, and the superior femoropatellar surface. In the contralateral joint, there was a 49% increase of proteoglycans in the inferior femoropatellar surface after remobilisation, while a 34% decrease was simultaneously noticed on the summit of the medial femoral condyle. Total proteoglycan synthesis was not significantly changed after immobilisation or 50 weeks' remobilisation in the treated or contralateral joint, compared with age matched controls. The chondroitin 6- to 4- sulphate ratio was reduced by immobilisation both in the radioactively labelled and the total tissue proteoglycans. In the remobilised joint, this ratio was restored in femur, while in tibia it remained at a level lower than controls. Neither immobilisation nor remobilisation induced epitopes recognised by the monoclonal antibody 3B3 on native (undigested) proteoglycans.CONCLUSION: These results show that the depletion of proteoglycans observed after 11 weeks of immobilisation was not completely restored in certain surface sites after 50 weeks of remobilisation. The significant changes that developed in the contralateral joint during the remobilisation period give further support to the idea that a permanent alteration of matrix metabolism results even from a temporary modification of loading pattern in immature joints.
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| 7542. |
- Jortikka, Matti, et al.
(författare)
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The role of microtubules in the regulation of proteoglycan synthesis in chondrocytes under hydrostatic pressure.
- 2000
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Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier. - 0003-9861 .- 1096-0384. ; 374:2, s. 172-180
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Tidskriftsartikel (refereegranskat)abstract
- Chondrocytes of the articular cartilage sense mechanical factors associated with joint loading, such as hydrostatic pressure, and maintain the homeostasis of the extracellular matrix by regulating the metabolism of proteoglycans (PGs) and collagens. Intermittent hydrostatic pressure stimulates, while continuous high hydrostatic pressure inhibits, the biosynthesis of PGs. High continuous hydrostatic pressure also changes the structure of cytoskeleton and Golgi complex in cultured chondrocytes. Using microtubule (MT)-affecting drugs nocodazole and taxol as tools we examined whether MTs are involved in the regulation of PG synthesis in pressurized primary chondrocyte monolayer cultures. Disruption of the microtubular array by nocodazole inhibited [(35)S]sulfate incorporation by 39-48%, while MT stabilization by taxol caused maximally a 17% inhibition. Continuous hydrostatic pressure further decreased the synthesis by 34-42% in nocodazole-treated cultures. This suggests that high pressure exerts its inhibitory effect through mechanisms independent of MTs. On the other hand, nocodazole and taxol both prevented the stimulation of PG synthesis by cyclic 0. 5 Hz, 5 MPa hydrostatic pressure. The drugs did not affect the structural and functional properties of the PGs, and none of the treatments significantly affected cell viability, as indicated by the high level of PG synthesis 24-48 h after the release of drugs and/or high hydrostatic pressure. Our data on two-dimensional chondrocyte cultures indicate that inhibition of PG synthesis by continuous high hydrostatic pressure does not interfere with the MT-dependent vesicle traffic, while the stimulation of synthesis by cyclic pressure does not occur if the dynamic nature of MTs is disturbed by nocodazole. Similar phenomena may operate in cartilage matrix embedded chondrocytes.
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| 7543. |
- Jose Bullejos, Francisco, et al.
(författare)
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Nucleic Acid Content in Crustacean Zooplankton : Bridging Metabolic and Stoichiometric Predictions
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:1, s. e86493-
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Tidskriftsartikel (refereegranskat)abstract
- Metabolic and stoichiometric theories of ecology have provided broad complementary principles to understand ecosystem processes across different levels of biological organization. We tested several of their cornerstone hypotheses by measuring the nucleic acid (NA) and phosphorus (P) content of crustacean zooplankton species in 22 high mountain lakes (Sierra Nevada and the Pyrenees mountains, Spain). The P-allocation hypothesis (PAH) proposes that the genome size is smaller in cladocerans than in copepods as a result of selection for fast growth towards P-allocation from DNA to RNA under P limitation. Consistent with the PAH, the RNA: DNA ratio was > 8-fold higher in cladocerans than in copepods, although 'fast-growth' cladocerans did not always exhibit higher RNA and lower DNA contents in comparison to 'slow-growth' copepods. We also showed strong associations among growth rate, RNA, and total P content supporting the growth rate hypothesis, which predicts that fast-growing organisms have high P content because of the preferential allocation to P-rich ribosomal RNA. In addition, we found that ontogenetic variability in NA content of the copepod Mixodiaptomus laciniatus (intra-and interstage variability) was comparable to the interspecific variability across other zooplankton species. Further, according to the metabolic theory of ecology, temperature should enhance growth rate and hence RNA demands. RNA content in zooplankton was correlated with temperature, but the relationships were nutrient-dependent, with a positive correlation in nutrient-rich ecosystems and a negative one in those with scarce nutrients. Overall our results illustrate the mechanistic connections among organismal NA content, growth rate, nutrients and temperature, contributing to the conceptual unification of metabolic and stoichiometric theories.
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| 7544. |
- Josefson, Rebecca
(författare)
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Proteostasis beyond chaperones - Auxiliary systems in the management of damaged proteins
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aging entails loss of functionality and increased risk of death, even for unicellular organisms, such as the yeast Saccharomyces cerevisiae. On a cellular level, aging is accompanied by an accumulation of harmful aging factors, e.g. damaged and aggregated proteins. Environmental stress can also cause a protein to misfold, leading to loss of function and aggregation. Protein misfolding is counteracted by systems of protein quality control. The temporal protein quality control system acts to refold or degrade the misfolded protein, while the spatial protein quality control system sorts damaged proteins to specific inclusion sites to prevent toxicity. The proteostasis network is defined as the cellular machineries involved in protein synthesis, folding and degradation. Other systems affecting proteins and protein folding status are considered auxiliary systems to proteostasis. This thesis is based on genome-wide studies of S. cerevisiae aimed at finding new components in asymmetric inheritance of damaged proteins and the overall capacity of the cell to prevent protein aggregates. Vac17 was identified as a limiting factor for asymmetric inheritance, inclusion formation, endocytosis and lifespan. The effect of Vac17 on these processes requires endosomal components and fusion to the vacuole. In addition, I found that the GET pathway is a limiting factor in protein folding, as disruption causes massive aggregation of several proteins, not only substrates of the GET pathway. Given the major impact of these auxiliary systems on proteostatic processes, they should be considered part of the proteostasis network.
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| 7545. |
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| 7546. |
- Josefsson, Leila, et al.
(författare)
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Potato Protein Nanofibrils Produced from a Starch Industry Sidestream
- 2020
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Ingår i: ACS Sustainable Chemistry and Engineering. - : AMER CHEMICAL SOC. - 2168-0485. ; 8:2, s. 1058-1067
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Tidskriftsartikel (refereegranskat)abstract
- Protein nanofibrils have emerged as promising building blocks in functional bio/nanomaterials as well as in food products. We here demonstrate that nanofibrils with amyloid-like properties can be produced from potato protein isolate, a major sidestream from the starch industry. Methods for solubilization of potato proteins are evaluated, and a protocol for the assembly of protein nanofibrils is presented. Characterization of the nanofibrils shows that they are rich in beta-sheet structure and display the cross-beta X-ray fiber diffraction pattern, which is a hallmark of amyloid-like fibrils. Atomic force microscopy shows that the fibrils are ca. 4-5 nm in diameter with a nanoscale morphology that displays a high degree of curvature. Using mass spectrometry we identify four peptides that constitute the core building blocks of the nanofibrils and show that they originate from two different classes of proteins. The structural characteristics of these peptides are distinct from previously studied plant protein nanofibrils and thereby reveal new knowledge about the formation of protein nanostructures from agricultural resources.
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| 7547. |
- Josephy, P. David, et al.
(författare)
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Screening and characterization of variant Theta-class glutathione transferases catalyzing the activation of ethylene dibromide to a mutagen
- 2006
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Ingår i: Environmental and Molecular Mutagenesis. - : Wiley. - 0893-6692 .- 1098-2280. ; 47:9, s. 657-665
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Tidskriftsartikel (refereegranskat)abstract
- Ethylene dibromide (EDB) is a widespread environmental pollutant and mutagen/carcinogen. Certain Theta-class glutathione transferases (GSTs), enzymes that catalyze the reaction of reduced glutathione (GSH) with electrophiles, activate EDB to a mutagen. Previous studies have shown that human GST T1-1, but not rat GST T2-2, activates EDB. We have constructed an E. coli lacZ reversion mutagenicity assay system in which expression of recombinant GST supports activation of EDB to a mutagen. Hexa-histidine N-terminal tagging of GST T1-1 results in greatly enhanced expression of the recombinant enzyme and gives a lacZ strain that shows a mutagenic response to EDB at extremely low levels ( approximately 1 ng EDB per plate). The hexa-histidine-tagged enzyme was purified in one step by Ni(2+)-affinity chromatography. We applied the lacZ mutagenicity assay to the rapid screening of a library of variant GST Theta enzymes. Sequence variants with altered catalytic activities were identified, purified, and characterized.
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| 7548. |
- Jouhten, P., et al.
(författare)
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Predictive evolution of metabolic phenotypes using model-designed environments
- 2022
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Ingår i: Molecular Systems Biology. - : EMBO. - 1744-4292. ; 18:10
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Tidskriftsartikel (refereegranskat)abstract
- Adaptive evolution under controlled laboratory conditions has been highly effective in selecting organisms with beneficial phenotypes such as stress tolerance. The evolution route is particularly attractive when the organisms are either difficult to engineer or the genetic basis of the phenotype is complex. However, many desired traits, like metabolite secretion, have been inaccessible to adaptive selection due to their trade-off with cell growth. Here, we utilize genome-scale metabolic models to design nutrient environments for selecting lineages with enhanced metabolite secretion. To overcome the growth-secretion trade-off, we identify environments wherein growth becomes correlated with a secondary trait termed tacking trait. The latter is selected to be coupled with the desired trait in the application environment where the trait manifestation is required. Thus, adaptive evolution in the model-designed selection environment and subsequent return to the application environment is predicted to enhance the desired trait. We experimentally validate this strategy by evolving Saccharomyces cerevisiae for increased secretion of aroma compounds, and confirm the predicted flux-rerouting using genomic, transcriptomic, and proteomic analyses. Overall, model-designed selection environments open new opportunities for predictive evolution.
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| 7549. |
- Jouve, HM, et al.
(författare)
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Structural analysis of compound I in hemoproteins: Study on Proteus mirabilis catalase
- 1997
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Ingår i: BIOCHIMIE. - : EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER. - 0300-9084. ; 79:11, s. 667-671
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Tidskriftsartikel (refereegranskat)abstract
- Ferryl catalysis has attracted considerable interest, because a diverse variety of enzymes use ferryl intermediates to perform difficult chemistry. The structure of the reactional intermediate compound I of Proteus mirabilis catalase (PMC) has been solve
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| 7550. |
- Jovells-Vaqué, Sílvia, et al.
(författare)
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The aberrant hamster Melissiodon (Cricetidae, Rodentia) from the early Miocene of Echzell and other German and French localities
- 2022
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Ingår i: Historical Biology. - : Taylor & Francis. - 0891-2963 .- 1029-2381. ; 35:6, s. 821-831
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Tidskriftsartikel (refereegranskat)abstract
- Melissiodon is a rare cricetid with a long stratigraphic range, present from the Oligocene until the Miocene, only found in western and central Europe except some specimens recovered in Anatolia. What makes Melissiodon special is its unique dental and mandible morphology that has led to many questions regarding its relationship to other cricetid genera and its type of diet. In this work, we have studied new material attributed to Melissiodon from the German localities Echzell (MN4) and Petersbuch (MN3 and MN4), and from the French locality Beaulieu (MN3). Moreover, we compared these specimens with the already published material from other localities across western and central Europe during the early Miocene (MN3 and MN4). In conclusion, the studied specimens and the comparison with other material from different European localities allow us to ascribe this new material as Melissiodon dominans, a widely dispersed species across Europe during the early Miocene.
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