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- Chen, Hwei-yen, 1983-, et al.
(författare)
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Germline mutation rate is elevated in young and old parents in Caenorhabditis remanei
- 2023
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Ingår i: Evolution Letters. - : Oxford University Press. - 2056-3744. ; 7:6, s. 478-489
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Tidskriftsartikel (refereegranskat)abstract
- The effect of parental age on germline mutation rate across generations is not fully understood. While some studies report a positive linear relationship of mutation rate with increasing age, others suggest that mutation rate varies with age but not in a linear fashion. We investigated the effect of parental age on germline mutations by generating replicated mutation accumulation lines in Caenorhabditis remanei at three parental ages ("Young T1" [Day 1], "Peak T2" [Day 2], and "Old T5" [Day 5] parents). We conducted whole-genome resequencing and variant calling to compare differences in mutation rates after three generations of mutation accumulation. We found that Peak T2 lines had an overall reduced mutation rate compared to Young T1 and Old T5 lines, but this pattern of the effect varied depending on the variant impact. Specifically, we found no high-impact variants in Peak T2 lines, and modifiers and up- and downstream gene variants were less frequent in these lines. These results suggest that animals at the peak of reproduction have better DNA maintenance and repair compared to young and old animals. We propose that C. remanei start to reproduce before they optimize their DNA maintenance and repair, trading the benefits of earlier onset of reproduction against offspring mutation load. The increase in offspring mutation load with age likely represents germline senescence. Germline mutations play a key role in evolution through the generation of novel genotypes. Estimating the mutation rate in species, populations, and individuals is one way to understand the relative timeframe of evolutionary processes, for the timing of historical events and for estimating heritability of traits and diseases. Individual age at reproduction is known to affect the number of mutations being transferred into the next generation and generally mutation rate is thought to increase with increasing parental age. However, preventing mutations in germ cells is potentially costly and it may pay off to optimize germline genome repair and maintenance during peak reproductive periods, and relax it during nonpeak periods. This idea has been put forward to explain for example the reduction of gonad size in seasonally reproducing animals during nonreproductive periods and supported by the finding that the mutation rate seems to be higher in teenage men compared to men during their peak reproductive ages. We further tested this idea of a nonlinear relationship between age and mutation rate by performing a mutation accumulation experiment in a short-lived nematode. We kept experimental lines and allowed adults to reproduce at different ages in different lines, with some lines reproducing before, some during, and some after their reproductive peak. We found that mutation rates are higher in nematode lines reproducing before or after the reproductive peak compared to those reproducing during the peak. Our results therefore support the idea that germline genome maintenance and repair is potentially costly and that the mutation rate does not just increase with age but is optimized during the peak reproductive age of an organism.
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| 3. |
- Freyschlag, Christian F, et al.
(författare)
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Imaging practice in low-grade gliomas among European specialized centers and proposal for a minimum core of imaging.
- 2018
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Ingår i: Journal of Neuro-Oncology. - : Springer Science and Business Media LLC. - 0167-594X .- 1573-7373. ; 139:3, s. 699-711
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Imaging studies in diffuse low-grade gliomas (DLGG) vary across centers. In order to establish a minimal core of imaging necessary for further investigations and clinical trials in the field of DLGG, we aimed to establish the status quo within specialized European centers.METHODS: An online survey composed of 46 items was sent out to members of the European Low-Grade Glioma Network, the European Association of Neurosurgical Societies, the German Society of Neurosurgery and the Austrian Society of Neurosurgery.RESULTS: A total of 128 fully completed surveys were received and analyzed. Most centers (n = 96, 75%) were academic and half of the centers (n = 64, 50%) adhered to a dedicated treatment program for DLGG. There were national differences regarding the sequences enclosed in MRI imaging and use of PET, however most included T1 (without and with contrast, 100%), T2 (100%) and TIRM or FLAIR (20, 98%). DWI is performed by 80% of centers and 61% of centers regularly performed PWI.CONCLUSION: A minimal core of imaging composed of T1 (w/wo contrast), T2, TIRM/FLAIR, PWI and DWI could be identified. All morphologic images should be obtained in a slice thickness of ≤ 3 mm. No common standard could be obtained regarding advanced MRI protocols and PET.IMPORTANCE OF THE STUDY: We believe that our study makes a significant contribution to the literature because we were able to determine similarities in numerous aspects of LGG imaging. Using the proposed "minimal core of imaging" in clinical routine will facilitate future cooperative studies.
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| 4. |
- Lind, Martin I., Dr, 1980-, et al.
(författare)
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Environmental variation mediates the evolution of anticipatory parental effects
- 2020
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Ingår i: Evolution Letters. - Oxford : John Wiley & Sons. - 2056-3744. ; 4:4, s. 371-381
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Tidskriftsartikel (refereegranskat)abstract
- Theory maintains that when future environment is predictable, parents should adjust the phenotype of their offspring to match the anticipated environment. The plausibility of positive anticipatory parental effects is hotly debated and the experimental evidence for the evolution of such effects is currently lacking. We experimentally investigated the evolution of anticipatory maternal effects in a range of environments that differ drastically in how predictable they are. Populations of the nematode Caenorhabditis remanei, adapted to 20°C, were exposed to a novel temperature (25°C) for 30 generations with either positive or zero correlation between parent and offspring environment. We found that populations evolving in novel environments that were predictable across generations evolved a positive anticipatory maternal effect, because they required maternal exposure to 25°C to achieve maximum reproduction in that temperature. In contrast, populations evolving under zero environmental correlation had lost this anticipatory maternal effect. Similar but weaker patterns were found if instead rate-sensitive population growth was used as a fitness measure. These findings demonstrate that anticipatory parental effects evolve in response to environmental change so that ill-fitting parental effects can be rapidly lost. Evolution of positive anticipatory parental effects can aid population viability in rapidly changing but predictable environments. © 2020 The Authors. Evolution Letters published by Wiley Periodicals LLC on behalf of Society for the Study of Evolution (SSE) and European Society for Evolutionary Biology (ESEB).
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