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Jonathan M. Palozzi Swathi P. Jeedigunta Thomas R. Hurd 《Journal of molecular biology》2018,430(24):4834-4848
Numerous mitochondrial quality control mechanisms exist within cells, but none have been shown to effectively assess and control the quality of mitochondrial DNA (mtDNA). One reason such mechanisms have yet to be elucidated is that they do not appear to be particularly active in most somatic cells, where many studies are conducted. The female germline, the cell lineage that gives rise to eggs, appears to be an exception. In the germline, strong purifying selection pathways act to eliminate deleterious mtDNA. These pathways have apparently evolved to prevent pathogenic mtDNA mutations from accumulating over successive generations and causing a decline of species via Muller's ratchet. Despite their fundamental biological importance, the mechanisms underlying purifying selection remain poorly understood, with no genes involved in this process yet identified. In this review, we discuss recent studies exploring mechanisms of germline mtDNA purifying selection in both mammalian and invertebrate systems. We also discuss the challenges to future major advances. Understanding the molecular basis of purifying selection is not only a fundamental outstanding question in biology, but may also pave the way to controlling selection in somatic tissues, potentially leading to treatments for people suffering from mitochondrial diseases. 相似文献
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Aims
Warming has the potential to alter plant litter mass loss and nutrient release during decomposition. However, a great deal of uncertainty remains concerning how other factors such as litter species or substrate quality might modify the effects of increased temperature on decomposition. Meanwhile, the temperature sensitivity of plant litter decay in tropical and subtropical forest ecosystems remains poorly resolved.Methods
This study was designed to assess the effects of experimental warming on litter decomposition and nutrient release of two contrasting tree species (Schima superba and Machilus breviflora) by translocating model forest ecosystems from the high-elevation sites to the lower-elevation sites in subtropical China. Translocating model mountain evergreen broad-leaved forest (MEBF) to the altitude of 300 m and 30 m increased the average monthly soil temperature at 5 cm depth by 0.88 and 1.84 °C, respectively during the experimental period. Translocating model coniferous and broad-leaved mixed forest (CBMF) to the altitude of 30 m increased the average monthly soil temperature at 5 cm depth by 0.85 °C.Results
We found that experimental warming accelerated litter decomposition in both model forest types, and the promoting efficiency was greater when the temperature increased. The litter with high quality (Schima superba) had stronger response to warming than low quality litter (Machilus breviflora). Warming accelerated Na, K, Mg, P, N and Ca release from Schima superba litter, but only simulated Ca release from Machilus breviflora litter. Overall, litter decomposition was controlled by the order: soil temperature > litter quality > soil moisture > litter incubation forest type under experimental warming in the subtropical China.Conclusion
We conclude that leaf litter decomposition was facilitated by experimental warming in subtropical China. Litter species might modify the effects of increased temperature on litter decomposition; however, forest type has no effect on litter decomposition.
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