| 1. |
- Crona, Mikael, et al.
(författare)
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A Rare Combination of Ribonucleotide Reductases in the Social Amoeba Dictyostelium discoideum
- 2013
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 288:12, s. 8198-8208
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Tidskriftsartikel (refereegranskat)abstract
- Ribonucleotide reductases (RNRs) catalyze the only pathway for de novo synthesis of deoxyribonucleotides needed for DNA replication and repair. The vast majority of eukaryotes encodes only a class I RNR, but interestingly some eukaryotes, including the social amoeba Dictyostelium discoideum, encode both a class I and a class II RNR. The amino acid sequence of the D. discoideum class I RNR is similar to other eukaryotic RNRs, whereas that of its class II RNR is most similar to the monomeric class II RNRs found in Lactobacillus spp. and a few other bacteria. Here we report the first study of RNRs in a eukaryotic organism that encodes class I and class II RNRs. Both classes of RNR genes were expressed in D. discoideum cells, although the class I transcripts were more abundant and strongly enriched during mid-development compared with the class II transcript. The quaternary structure, allosteric regulation, and properties of the diiron-oxo/radical cofactor of D. discoideum class I RNR are similar to those of the mammalian RNRs. Inhibition of D. discoideum class I RNR by hydroxyurea resulted in a 90% reduction in spore formation and decreased the germination viability of the surviving spores by 75%. Class II RNR could not compensate for class I inhibition during development, and an excess of vitamin B12 coenzyme, which is essential for class II activity, did not improve spore formation. We suggest that class I is the principal RNR during D. discoideum development and growth and is important for spore formation, possibly by providing dNTPs for mitochondrial replication.
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| 2. |
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| 3. |
- Fagerqvist, Therese, et al.
(författare)
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Off-pathway alpha-synuclein oligomers seem to alter alpha-synuclein turnover in a cell model but lack seeding capability in vivo
- 2013
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Ingår i: Amyloid. - : Informa UK Limited. - 1350-6129 .- 1744-2818. ; 20:4, s. 233-244
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Tidskriftsartikel (refereegranskat)abstract
- Aggregated α-synuclein is the major component of Lewy bodies, protein inclusions observed in the brain in neurodegenerative disorders such as Parkinson’s disease and dementia with Lewy bodies. Experimental evidence indicates that α-synuclein potentially can be transferred between cells and act as a seed to accelerate the aggregation process. Here, we investigated in vitro and in vivo seeding effects of α-synuclein oligomers induced by the reactive aldehyde 4-oxo-2-nonenal (ONE). As measured by a Thioflavin-T based fibrillization assay, there was an earlier onset of aggregation when α-synuclein oligomers were added to monomeric α-synuclein. In contrast, exogenously added α-synuclein oligomers did not induce aggregation in a cell model. However, cells overexpressing α-synuclein that were treated with the oligomers displayed reduced α-synuclein levels, indicating that internalized oligomers either decreased the expression or accelerated the degradation of transfected α-synuclein. Also in vivo there were no clear seeding effects, as intracerebral injections of α-synuclein oligomers into the neocortex of α-synuclein transgenic mice did not induce formation of Proteinase K resistant α-synuclein pathology. Taken together, we could observe a seeding effect of the ONE-induced α-synuclein oligomers in a fibrillization assay, but neither in a cell nor in a mouse model.
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| 4. |
- Fagerqvist, Therese, et al.
(författare)
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Off-pathway α-synuclein oligomers seem to alter α-synuclein turnover in a cell model but lack seeding capability in vivo
- 2013
-
Ingår i: Amyloid. - : Informa Healthcare. - 1350-6129 .- 1744-2818. ; 20:4, s. 233-244
-
Tidskriftsartikel (refereegranskat)abstract
- Aggregated alpha-synuclein is the major component of Lewy bodies, protein inclusions observed in the brain in neurodegenerative disorders such as Parkinson's disease and dementia with Lewy bodies. Experimental evidence indicates that alpha-synuclein potentially can be transferred between cells and act as a seed to accelerate the aggregation process. Here, we investigated in vitro and in vivo seeding effects of alpha-synuclein oligomers induced by the reactive aldehyde 4-oxo-2-nonenal (ONE). As measured by a Thioflavin-T based fibrillization assay, there was an earlier onset of aggregation when alpha-synuclein oligomers were added to monomeric alpha-synuclein. In contrast, exogenously added alpha-synuclein oligomers did not induce aggregation in a cell model. However, cells overexpressing alpha-synuclein that were treated with the oligomers displayed reduced alpha-synuclein levels, indicating that internalized oligomers either decreased the expression or accelerated the degradation of transfected alpha-synuclein. Also in vivo there were no clear seeding effects, as intracerebral injections of alpha-synuclein oligomers into the neocortex of alpha-synuclein transgenic mice did not induce formation of proteinase K resistant alpha-synuclein pathology. Taken together, we could observe a seeding effect of the ONE-induced alpha-synuclein oligomers in a fibrillization assay, but neither in a cell nor in a mouse model.
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| 5. |
- Nystedt, Björn, et al.
(författare)
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The Norway spruce genome sequence and conifer genome evolution
- 2013
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 497:7451, s. 579-584
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Tidskriftsartikel (refereegranskat)abstract
- Conifers have dominated forests for more than 200 million years and are of huge ecological and economic importance. Here we present the draft assembly of the 20-gigabase genome of Norway spruce (Picea abies), the first available for any gymnosperm. The number of well-supported genes (28,354) is similar to the >100 times smaller genome of Arabidopsis thaliana, and there is no evidence of a recent whole-genome duplication in the gymnosperm lineage. Instead, the large genome size seems to result from the slow and steady accumulation of a diverse set of long-terminal repeat transposable elements, possibly owing to the lack of an efficient elimination mechanism. Comparative sequencing of Pinus sylvestris, Abies sibirica, Juniperus communis, Taxus baccata and Gnetum gnemon reveals that the transposable element diversity is shared among extant conifers. Expression of 24-nucleotide small RNAs, previously implicated in transposable element silencing, is tissue-specific and much lower than in other plants. We further identify numerous long (>10,000 base pairs) introns, gene-like fragments, uncharacterized long non-coding RNAs and short RNAs. This opens up new genomic avenues for conifer forestry and breeding.
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