How much heat can we grow in our cities? Modelling UK urban biofuel production potential

Biofuel provides a globally significant opportunity to reduce fossil fuel dependence; however, its sustainability can only be meaningfully explored for individual cases. It depends on multiple considerations including: life cycle greenhouse gas emissions, air quality impacts, food versus fuel trade‐offs, biodiversity impacts of land use change and socio‐economic impacts of energy transitions. One solution that may address many of these issues is local production of biofuel on non‐agricultural land. Urban areas drive global change, for example, they are responsible for 70% of global energy use, but are largely ignored in their resource production potential; however, underused urban greenspaces could be utilized for biofuel production near the point of consumption. This could avoid food versus fuel land conflicts in agricultural land and long‐distance transport costs, provide ecosystem service benefits to urban dwellers and increase the sustainability and resilience of cities and towns. Here, we use a Geographic Information System to identify urban greenspaces suitable for biofuel production, using exclusion criteria, in 10 UK cities. We then model production potential of three different biofuels: Miscanthus grass, short rotation coppice (SRC) willow and SRC poplar, within the greenspaces identified and extrapolate up to a UK‐scale. We demonstrate that approximately 10% of urban greenspace (3% of built‐up land) is potentially suitable for biofuel production. We estimate the potential of this to meet energy demand through heat generation, electricity and combined heat and power (CHP) operations. Our findings show that, if fully utilized, urban biofuel production could meet nearly a fifth of demand for biomass in CHP systems in the United Kingdom's climate compatible energy scenarios by 2030, with potentially similar implications for other comparable countries and regions.     

Simulation modeling reveals the evolutionary role of landscape shape and species dispersal on genetic variation within a metapopulation

Different shapes of landscape boundaries can affect the habitat networks within them and consequently the spatial genetic-patterns of a metapopulation. In this study, we used a mechanistic framework to evaluate the effects of landscape shape, through watershed elongation, on genetic divergence among populations at the metapopulation scale. Empirical genetic data from four, sympatric stream-macroinvertebrates having aerial adults were collected from streams in Japan to determine the roles of species-specific dispersal strategies on metapopulation genetics. Simulation results indicated that watershed elongation allows the formation of river networks with fewer branches and larger topographic constraints. This results in decreased interpopulation connectivity but a lower level of spatial isolation of distal populations (e.g. those found in headwaters) occurring in the landscapes examined. Distal populations had higher genetic divergence when their downstream-biased dispersal (relative to upstream- and/or overland-biased dispersal) was high. This underscores the importance of distal populations influencing genetic divergence at the metapopulation scale for species having downstream-biased dispersal. In turn, lower genetic divergence was observed under watershed elongation when the genetic isolation of distal populations was decreased in such species. This strong association between landscape shape and evolutionary processes highlights the importance of natural, spatial architecture in assessing the effectiveness of conservation and management strategies.     

Chloroplasts require glutathione reductase to balance reactive oxygen species and maintain efficient photosynthesis

Thiol‐based redox‐regulation is vital for coordinating chloroplast functions depending on illumination and has been throroughly investigated for thioredoxin‐dependent processes. In parallel, glutathione reductase (GR) maintains a highly reduced glutathione pool, enabling glutathione‐mediated redox buffering. Yet, how the redox cascades of the thioredoxin and glutathione redox machineries integrate metabolic regulation and detoxification of reactive oxygen species remains largely unresolved because null mutants of plastid/mitochondrial GR are embryo‐lethal in Arabidopsis thaliana. To investigate whether maintaining a highly reducing stromal glutathione redox potential (E_GSH) via GR is necessary for functional photosynthesis and plant growth, we created knockout lines of the homologous enzyme in the model moss Physcomitrella patens. In these viable mutant lines, we found decreasing photosynthetic performance and plant growth with increasing light intensities, whereas ascorbate and zeaxanthin/antheraxanthin levels were elevated. By in vivo monitoring stromal E_GSH dynamics, we show that stromal E_GSH is highly reducing in wild‐type and clearly responsive to light, whereas an absence of GR leads to a partial glutathione oxidation, which is not rescued by light. By metabolic labelling, we reveal changing protein abundances in the GR knockout plants, pinpointing the adjustment of chloroplast proteostasis and the induction of plastid protein repair and degradation machineries. Our results indicate that the plastid thioredoxin system is not a functional backup for the plastid glutathione redox systems, whereas GR plays a critical role in maintaining efficient photosynthesis.     

Contrasted histories of organelle and nuclear genomes underlying physiological diversification in a grass species

C₄ photosynthesis evolved multiple times independently in angiosperms, but most origins are relatively old so that the early events linked to photosynthetic diversification are blurred. The grass Alloteropsis semialata is an exception, as this species encompasses C₄ and non-C₄ populations. Using phylogenomics and population genomics, we infer the history of dispersal and secondary gene flow before, during and after photosynthetic divergence in A. semialata. We further analyse the genome composition of individuals with varied ploidy levels to establish the origins of polyploids in this species. Detailed organelle phylogenies indicate limited seed dispersal within the mountainous region of origin and the emergence of a C₄ lineage after dispersal to warmer areas of lower elevation. Nuclear genome analyses highlight repeated secondary gene flow. In particular, the nuclear genome associated with the C₄ phenotype was swept into a distantly related maternal lineage probably via unidirectional pollen flow. Multiple intraspecific allopolyploidy events mediated additional secondary genetic exchanges between photosynthetic types. Overall, our results show that limited dispersal and isolation allowed lineage divergence, with photosynthetic innovation happening after migration to new environments, and pollen-mediated gene flow led to the rapid spread of the derived C₄ physiology away from its region of origin.     

Optimization of culture media to enhance the growth of tissue engineered cartilage

Tissue engineering is a promising option for cartilage repair. However, several hurdles still need to be overcome to develop functional tissue constructs suitable for implantation. One of the most common challenges is the general low capacity of chondrocytes to synthesize cartilage-specific extracellular matrix (ECM). While different approaches have been explored to improve the biosynthetic response of chondrocytes, several studies have demonstrated that the nutritional environment (e.g., glucose concentration and media volume) can have a profound effect on ECM synthesis. Thus, the purpose of this study was to optimize the formulation of cell culture media to upregulate the accumulation of cartilaginous ECM constituents (i.e., proteoglycans and collagen) by chondrocytes in 3D culture. Using response surface methodology, four different media factors (basal media, media volume, glucose, and glutamine) were first screened to determine optimal media formulations. Constructs were then cultured under candidate optimal media formulations for 4 weeks and analyzed for their biochemical and structural properties. Interestingly, the maximal accumulation of proteoglycans and collagen appeared to be elicited by different media formulations. Most notably, proteoglycan accumulation was favored by high volume, low glucose-containing DMEM/F12 (1:1) media whereas collagen accumulation was favored by high volume, high glucose-containing F12 media. While high glutamine-containing media elicited increased DNA content, glutamine concentration had no apparent effect on ECM accumulation. Therefore, optimizing the nutritional environment during chondrocyte culture appears to be a promising, straight-forward approach to improve cartilaginous tissue formation. Future work will investigate the combined effects of the nutritional environment and external stimuli.     

Larval host plants of two lizard beetles in the genus Tetraphala (Coleoptera,Erotylidae, Languriinae,Languriini) from Taiwan,with a host plant list of Languriini

Lizard beetles (Erotylidae, Languriinae, Languriini) are known as stem borers of plants and contain agricultural pests and endangered species, but their species–host plant associations have been poorly documented. Here we investigated the larval host plants of two species of the genus Tetraphala Strum, T. collaris (Crotch) and Tetraphala sp. occurring in Taiwan. Females of T. collaris excavated living leafstalks and stems of the herbaceous dicot, Sambucus chinensis (Adoxaceae) using their mandibles for oviposition. We observed the eggs and early-instar larvae inside and nearby oviposition holes and late-instar larvae inside stems, suggesting that T. collaris uses living leafstalks and stems of S. chinensis as oviposition substrate and the larvae tunnel into stems with feeding on the tissues. Similarly, females of Tetraphala sp. excavated living leafstalks of the fern, Pteris wallichiana (Pteridaceae) using their mandibles for oviposition. We observed the eggs and early-instar larvae inside and nearby oviposition holes. When reared in laboratory, a larva reached adulthood inside the leafstalk. These results indicated that Tetraphala sp. uses living leafstalks of Pt. wallichiana as oviposition substrate and the larvae complete their development within. This study revealed that the genus Tetraphala contains both fern- and dicot-users during larval period. Further study is needed to clarify the evolutionary process of host plant use of languriines. Additionally, the host plant list of Languriini is provided.