Variation in RNA Virus Mutation Rates across Host Cells

It is well established that RNA viruses exhibit higher rates of spontaneous mutation than DNA viruses and microorganisms. However, their mutation rates vary amply, from 10−6 to 10−4 substitutions per nucleotide per round of copying (s/n/r) and the causes of this variability remain poorly understood. In addition to differences in intrinsic fidelity or error correction capability, viral mutation rates may be dependent on host factors. Here, we assessed the effect of the cellular environment on the rate of spontaneous mutation of the vesicular stomatitis virus (VSV), which has a broad host range and cell tropism. Luria-Delbrück fluctuation tests and sequencing showed that VSV mutated similarly in baby hamster kidney, murine embryonic fibroblasts, colon cancer, and neuroblastoma cells (approx. 10−5 s/n/r). Cell immortalization through p53 inactivation and oxygen levels (1–21%) did not have a significant impact on viral replication fidelity. This shows that previously published mutation rates can be considered reliable despite being based on a narrow and artificial set of laboratory conditions. Interestingly, we also found that VSV mutated approximately four times more slowly in various insect cells compared with mammalian cells. This may contribute to explaining the relatively slow evolution of VSV and other arthropod-borne viruses in nature

The Gene Pool Concept Applied to Crop Wild Relatives: An Evolutionary Perspective

Crop wild relatives (CWR) can provide important resources for the genetic improvement of cultivated species. Because crops are often related to many wild species and because exploration of CWR for useful traits can take many years and substantial resources, the categorization of CWR based on a comprehensive assessment of their potential for use is an important knowledge foundation for breeding programs. The initial approach for categorizing CWR was based on crossing studies to empirically establish which species were interfertile with the crop. The foundational concept of distinct gene pools published almost 50 years ago was developed from these observations. However, the task of experimentally assessing all potential CWR proved too vast; therefore, proxies based on phylogenetic and other advanced scientific information have been explored. A current major approach to categorize CWR aims to comprehensively synthesize experimental data, taxonomic information, and phylogenetic studies. This approach very often ends up relying not only on the synthesis of data but also intuition and expert opinion and is therefore difficult to apply widely in a reproducible manner. Here, we explore the potential for a stronger standardization of the categorization method, with focus on evolutionary relationships among species combined with information on patterns of interfertility between species. Evolutionary relationships can be revealed with increasing resolution via next-generation sequencing, through the application of the multispecies coalescent model and using focused analyses on species discovery and delimitation that bridge population genetics and phylogenetics fields. Evolutionary studies of reproductive isolation can inform the understanding of patterns of interfertility in plants. For CWR, prezygotic postpollination reproductive barriers and intrinsic postzygotic barriers are the most important factors and determine the probability of producing viable and fertile offspring. To further the assessment of CWR for use in plant breeding, we present observed and predicted gene pool indices. The observed index quantifies patterns of interfertility based on fertilization success, seed production, offspring viability, and hybrid fertility. The predicted gene pool index requires further development of the understanding of quantitative and qualitative relationships between reproductive barriers, measures of genetic relatedness, and other relevant characteristics for crops and their wild relatives

Flow and particles deposition in anatomically realistic airways

The aerosol particles present in our environment are identified as increasingly risk factors for the human health. In particular, small particles that reach the surface of gas exchange in the alveolar region of lungs are considered most harmful to healt

Coupling N2 and CO2 in H2O to synthesize urea under ambient conditions

© 2020, The Author(s), under exclusive licence to Springer Nature Limited. The use of nitrogen fertilizers has been estimated to have supported 27% of the world’s population over the past century. Urea (CO(NH2)2) is conventionally synthesized through two consecutive industrial processes, N2 + H2 → NH3 followed by NH3 + CO2 → urea. Both reactions operate under harsh conditions and consume more than 2% of the world’s energy. Urea synthesis consumes approximately 80% of the NH3 produced globally. Here we directly coupled N2 and CO2 in H2O to produce urea under ambient conditions. The process was carried out using an electrocatalyst consisting of PdCu alloy nanoparticles on TiO2 nanosheets. This coupling reaction occurs through the formation of C–N bonds via the thermodynamically spontaneous reaction between *N=N* and CO. Products were identified and quantified using isotope labelling and the mechanism investigated using isotope-labelled operando synchrotron-radiation Fourier transform infrared spectroscopy. A high rate of urea formation of 3.36 mmol g–1 h–1 and corresponding Faradic efficiency of 8.92% were measured at –0.4 V versus reversible hydrogen electrode. [Figure not available: see fulltext.