| 71. |
- Sundh, Henrik, 1976, et al.
(författare)
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Environmental salinity regulates production rates of the antagonizing calciumreguatory hormones 1,25-dihydroxyvitamin D3 and 24,25- dihydroxyvitamin D3 in rainbow trout, Oncorhynchus mykiss
- 2007
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Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480. ; 152:2-3, s. 252-258
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies have shown that specific binding of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) to enterocyte basolateral membranes (BLM), as well as circulating concentrations, is affected in response to changes in environmental salinity. It is not known if the production of 1,25(OH)2D3 and 24,25(OH)2D3 is affected by environmental salinity. The aim of the present study was to measure the in vitro production of [3H]-1,25(OH)2D3 and [3H]-24,25(OH)2D3 in fresh water (FW) and after 1, 2, 3, and 7 days after transfer to seawater (SW). Pooled sub-cellular fractions (mitochondria and microsomes) from liver or kidney was incubated with [3H]-25(OH)D3 and the produced metabolites were separated using HPLC. Hepatic production of [3H]-1,25(OH)2D3 was decreased after 24 h in SW. This was followed by an up-regulation after 48 h and a second, slower decrease in production rate which leveled out after 7 days in SW. The production rate in SW was lower than the original rate in FW-adapted fish. For hepatic [3H]-24,25(OH)2D3 production the pattern was reversed. Renal production of [3H]-24,25(OH)2D3 increased significantly during the period of SW acclimation. These results suggest that environmental salinity regulates the production rate of the two antagonizing calcium regulatory hormones; 1,25(OH)2D3 and 24,25(OH)2D3. This gives further evidence to the hypothesis that there is a physiological regulation and a differentiated importance of 1,25(OH)2D3 and 24,25(OH)2D3 in relation to environmental calcium concentrations.
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| 72. |
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| 73. |
- Türk, Karin, et al.
(författare)
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NADH oxidation by the Na+-translocating NADH : quinone oxidoreductase from Vibrio cholerae
- 2004
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 279:20, s. 21349-21355
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Tidskriftsartikel (refereegranskat)abstract
- The Na(+)-translocating NADH:quinone oxidoreductase from Vibrio cholerae is a six subunit enzyme containing four flavins and a single motif for the binding of a Fe-S cluster on its NqrF subunit. This study reports the production of a soluble variant of NqrF (NqrF') and its individual flavin and Fe-S-carrying domains using V. cholerae or Escherichia coli as expression hosts. NqrF' and the flavin domain each contain 1 mol of FAD/mol of enzyme and exhibit high NADH oxidation activity (20,000 micromol min(-1) mg(-1)). EPR, visible absorption, and circular dichroism spectroscopy indicate that the Fe-S cluster in NqrF' and its Fe-S domain is related to 2Fe ferredoxins of the vertebrate-type. The addition of NADH to NqrF' results in the formation of a neutral flavosemiquinone and a partial reduction of the Fe-S cluster. The NqrF subunit harbors the active site of NADH oxidation and acts as a converter between the hydride donor NADH and subsequent one-electron reaction steps in the Na(+)-translocating NADH:quinone oxidoreductase complex. The observed electron transfer NADH --> FAD --> [2Fe-2S] in NqrF requires positioning of the FAD and the Fe-S cluster in close proximity in accordance with a structural model of the subunit.
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| 74. |
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| 75. |
- Zhuravleva, Anastasia, 1979, et al.
(författare)
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Divided evolution: a scheme for suppression of line broadening induced by conformational exchange
- 2008
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Ingår i: Journal of the American Chemical Society. - 0002-7863. ; 130:11, s. 3260-3260
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Tidskriftsartikel (refereegranskat)abstract
- We present a new signal acquisition scheme termed D-evolution that improves NMR spectra for systems undergoing conformational exchange in the intermediate time scale. The new approach separates time scales of the conformational exchange and chemical shift evolution. This reduces line broadening by avoiding the situation of intermediate exchange. The chemical shift evolution is divided into a number of short intervals interfaced by Carr-Purcell-Meiboom-Gill (CPMG) blocks. We demonstrate this method for several test systems such as small molecules, cyclohexane, and acetonitrile as well as two globular proteins, azurin and protein-L.
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| 76. |
- Alm Rosenblad, Magnus, 1957, et al.
(författare)
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Kinship in the SRP RNA family
- 2009
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Ingår i: RNA Biology. - 1547-6286. ; 6:5
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Tidskriftsartikel (refereegranskat)abstract
- The signal recognition particle (SRP) is a ribonucleoprotein complex which participates in the targeting of protein to cellular membranes. The RNA component of the SRP has been found in all domains of life, but the size of the molecule and the number of RNA secondary structure elements vary considerably between the different phylogenetic groups. We continued our efforts to identify new SRP RNAs, compare their sequences, discover new secondary structure elements, conserved motifs, and other properties. We found additional proof for the variability in the apical loop of helix 8, and we identified several bacteria which lack all of their SRP components. Based on the distribution of SRP RNA features within the taxonomy, we suggest seven alignment groups: Bacteria with a small (4.5S) SRP RNA, Bacteria with a large (6S) SRP RNA, Archaea, Fungi (Ascomycota), Metazoa group, Protozoa group, and Plants. The proposed divisions improve the prediction of more distantly related SRP RNAs and provide a more inclusive representation of the SRP RNA family. Updates of the Rfam SRP RNA sequence collection are expected to benefit from the suggested groupings.
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| 77. |
- Axelson-Fisk, Marina, et al.
(författare)
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Comparative genomics and gene finding in fungi
- 2006
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Ingår i: Topics in Current Genetics. ; 15, s. 1-28
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Forskningsöversikt (refereegranskat)abstract
- In the spring of 2005, we had access to 18 fully sequenced fungal genomes, and more are coming rapidly. New approaches and methods are being developed to harvest this information source to derive functional predictions and understanding of genome anatomy. Comparative genomics also tells us stories about the evolution of yeasts and filamentous fungi, and the genome rearrangements that marked their history. For example, several genes encoding proteins required for heterochromatin formation and RNA interference have been lost uniformly throughout the Hemiascomycetes, although some genes remain in a few species in a scattered pattern. Being the first eukaryote to have its genome fully sequenced, Saccharomyces cerevisiae was the forerunner for in silico methods of genome annotation in general, and gene finding in particular. Lessons learned from the comparatively simple genome of this budding yeast have paved the way for efficient genome analysis in other fungi as well as eukaryotes in general. Several fungal species are of important applied interest for mankind, and so it is essential to utilise comparative genomics to derive functional information about them. The set of fungal genomes: simple, related in evolution, and with a high density of functional information, can serve as a highly efficient test bed for the further development of comparative genomics.
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| 78. |
- Molin, Claes, 1977, et al.
(författare)
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mRNA stability changes precede changes in steady-state mRNA amounts during hyperosmotic stress
- 2009
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Ingår i: RNA. - : Cold Spring Harbor Laboratory. - 1355-8382 .- 1469-9001. ; 15:4, s. 600-614
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Tidskriftsartikel (refereegranskat)abstract
- Under stress, cells need to optimize the activity of a wide range of gene products during the response phases: shock, adaptation, and recovery. This requires coordination of several levels of regulation, including turnover and translation efficiencies ofmRNAs. Mitogen-activated protein (MAP) kinase pathways are implicated in many aspects of the environmental stress response,including initiation of transcription, translation efficiency, and mRNA turnover. In this study, we analyze mRNA turnover ratesand mRNA steady-state levels at different time points following mild hyperosmotic shock in Saccharomyces cerevisiae cells. Theregulation of mRNA stability is transient and affects most genes for which there is a change in transcript level. These changesprecede and prepare for the changes in steady-state levels, both regarding the initial increase and the later decline of stressinducedmRNAs. The inverse is true for stress-repressed genes, which become stabilized during hyperosmotic stress inpreparation of an increase as the cells recover. The MAP kinase Hog1 affects both steady-state levels and stability of stressresponsivetranscripts, whereas Rck2 influences steady-state levels without a major effect on stability. Regulation of mRNAstability is a wide-spread, but not universal, effect on stress-responsive transcripts during transient hyperosmotic stress. Bydestabilizing stress-induced mRNAs when their steady-state levels have reached a maximum, the cell prepares for thesubsequent recovery phase when these transcripts are to return to normal levels. Conversely, stabilization of stress-repressedmRNAs permits their rapid accumulation in the recovery phase. Our results show that mRNA turnover is coordinated withtranscriptional induction.
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| 79. |
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| 80. |
- Fritzsch, Guido, et al.
(författare)
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PCR Survey of Xenoturbella bocki Hox Genes
- 2008
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Ingår i: JOURNAL OF EXPERIMENTAL ZOOLOGY (MOL DEV EVOL). - : Wiley. ; 310B:3, s. 278-284
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Tidskriftsartikel (refereegranskat)abstract
- Xenoturbella bocki has recently been identified as one of the most basal deuterostomes, although an even more basal phylogenetic position cannot be ruled out. Here we report on a polymerase chain reaction survey of partial Hox homeobox sequences of X. bocki. Surprisingly, we did not find evidence for more than five Hox genes, one clear labial/PG1 ortholog, one posterior gene most similar to the PG9/10 genes of Ambulacraria, and three central group genes whose precise assignment to a specific paralog group remains open. We furthermore report on a re-evaluation of the available published evidence of Hox genes in other basal deuterostomes.
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