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- Friant, S, et al.
(författare)
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Interactions between Ty1 retrotransposon RNA and the T and D regions of the tRNA(iMet) primer are required for initiation of reverse transcription in vivo
- 1998
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Ingår i: Molecular and Cellular Biology. - 0270-7306 .- 1098-5549. ; 18:2, s. 799-806
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Tidskriftsartikel (refereegranskat)abstract
- Reverse transcription of the Saccharomyces cerevisiae Ty1 retrotransposon is primed by tRNA(iMet) base paired to the primer binding site (PBS) near the 5' end of Ty1 genomic RNA. The 10-nucleotide PBS is complementary to the last 10 nucleotides of the acceptor stem of tRNA(iMet). A structural probing study of the interactions between the Ty1 RNA template and the tRNA(iMet) primer showed that besides interactions between the PBS and the 3' end of tRNA(iMet), three short regions of Ty1 RNA, named boxes 0, 1, and 2.1, interact with the T and D stems and loops of tRNA(iMet). To determine if these sequences are important for the reverse transcription pathway of the Ty1 retrotransposon, mutant Ty1 elements and tRNA(iMet) were tested for the ability to support transposition. We show that the Ty1 boxes and the complementary sequences in the T and D stems and loops of tRNA(iMet) contain bases that are critical for Ty1 retrotransposition. Disruption of 1 or 2 bp between tRNA(iMet) and box 0, 1, or 2.1 dramatically decreases the level of transposition. Compensatory mutations which restore base pairing between the primer and the template restore transposition. Analysis of the reverse transcription intermediates generated inside Ty1 virus-like particles indicates that initiation of minus-strand strong-stop DNA synthesis is affected by mutations disrupting complementarity between Ty1 RNA and primer tRNA(iMet).
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| 2. |
- Anesio, Alexandre M, et al.
(författare)
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Decreased bacterial growth on vascular plant detritus due to photochemical modification
- 1999
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Ingår i: AQUATIC MICROBIAL ECOLOGY. - 0948-3055. ; 17:2, s. 159-165
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the effects of UV radiation on abiotic decomposition and dissolution of leaf Litter from the aquatic macrophyte Phragmites australis. Dead leaves were autoclaved and incubated in quartz tubes with autoclaved Milli-Q water, in darkness, und
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| 3. |
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| 4. |
- Bergman, Eva, et al.
(författare)
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Synthesis of theoretical and empirical experineces from nutrient and cyprinid reductions in Lake Ringsjön
- 1999
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Ingår i: Hydrobiologia. - 0018-8158. ; 404, s. 145-156
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Tidskriftsartikel (refereegranskat)abstract
- The reduction in external phosphorus load to Lake Ringsjön during the 1980s, did not result in improved water transparency during the following ten-year period. Furthermore, a fish-kill in the Eastern Basin of the lake, in addition to a cyprinid reduction programme (biomanipulation; 1988–1992), in contrast to theory, did not lead to any increase in zooplankton biomass or size. This absence of response in the pelagic food chain may have been attributed to the increase in abundance of YOY (0+) fish, following the fish reduction programme. Despite the lack of effect on zooplankton, there was a decrease in phytoplankton biomass, a change in species composition and an increase in water transparency following biomanipulation. In 1989, one year after the fish-kill in Eastern Basin, the Secchi depth (summer mean) increased from 60 cm to 110 cm. In the following years, water transparency increased further, despite an increase in phosphorus loading. An unexpected effect of the biomanipulation was an increase in benthic invertebrate and staging waterfowl abundances, which occurred 2–4 years after fish reduction. Hence, the response in the benthic community following biomanipulation was considerably stronger than in the pelagic community. A likely explanation is that reduction in abundance of the benthic feeding fish species bream (Abramis brama), strongly affected the benthic invertebrate fauna. In this paper, we present what we believe happened in Lake Ringsjön, and which processes are likely to have been important at various stages of the restoration process.
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| 5. |
- Hugosson, Håkan Wilhelm, 1972-, et al.
(författare)
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Theory of phase stabilities and bonding mechanisms in stoichiometric and substoichiometric molybdenum carbide
- 1999
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 86:7, s. 3758-3767
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACTFirst principles, total energy methods have been applied to predict the relative stabilities of the four experimentally verified MoC phases: the cubic δ(NaCl) phase and the three hexagonal γ(WC), η and γ′(TiAs) phases. The effect of vacancies on the relative stability of these four phases was investigated using a model structure with ordered vacancies within the carbon sublattice. For stoichiometric MoC, the γ phase was found to be the most stable followed by γ′, δ, and η, but for substoichiometric MoC0.75,MoC0.75, the order of relative stability was changed and the substoichiometric δ phase was found to have the lowest energy followed by γ′ and γ. A study of the electronic structure revealed vacancy induced peaks in the density of state and the electron density attached to these peaks was analyzed and found to emanate from unscreened Mo–Mo bonds through the carbon vacancy site. Finally, the oxygen stabilization of the γ′ MoC phase was studied.
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