Novel Miscanthus hybrids: Modelling productivity on marginal land in Europe using dynamics of canopy development determined by light interception

New biomass crop hybrids for bioeconomic expansion require yield projections to determine their potential for strategic land use planning in the face of global challenges. Our biomass growth simulation incorporates radiation interception and conversion efficiency. Models often use leaf area to predict interception which is demanding to determine accurately, so instead we use low-cost rapid light interception measurements using a simple laboratory-made line ceptometer and relate the dynamics of canopy closure to thermal time, and to measurements of biomass. We apply the model to project the European biomass potentials of new market-ready hybrids for 2020–2030. Field measurements are easier to collect, the calibration is seasonally dynamic and reduces influence of weather variation between field sites. The model obtained is conservative, being calibrated by crops of varying establishment and varying maturity on less productive (marginal) land. This results in conservative projections of miscanthus hybrids for 2020–2030 based on 10% land use conversion of the least (productive) grassland and arable for farm diversification, which show a European potential of 80.7–89.7 Mt year⁻¹ biomass, with potential for 1.2–1.3 EJ year⁻¹ energy and 36.3–40.3 Mt year⁻¹ carbon capture, with seeded Miscanthus sacchariflorus × sinensis displaying highest yield potential. Simulated biomass projections must be viewed in light of the field measurements on less productive land with high soil water deficits. We are attempting to model the results from an ambitious and novel project combining new hybrids across Europe with agronomy which has not been perfected on less productive sites. Nevertheless, at the time of energy sourcing issues, seed-propagated miscanthus hybrids for the upscaled provision of bioenergy offer an alternative source of renewable energy. If European countries provide incentives for growers to invest, seeded hybrids can improve product availability and biomass yields over the current commercial miscanthus variety.     

Poleward increase in feeding efficiency of leafminer Stigmella lapponica (Lepidoptera: Nepticulidae) in a latitudinal gradient crossing a boreal forest zone

Damage to plant communities imposed by insect herbivores generally decreases from low to high latitudes. This decrease is routinely attributed to declines in herbivore abundance and/or diversity, whereas latitudinal changes in per capita food consumption remain virtually unknown. Here, we tested the hypothesis that the lifetime food consumption by a herbivore individual decreases from low to high latitudes due to a temperature-driven decrease in metabolic expenses. From 2016 to 2019, we explored latitudinal changes in multiple characteristics of linear (gallery) mines made by larvae of the pygmy moth, Stigmella lapponica, in leaves of downy birch, Betula pubescens. The mined leaves were larger than intact leaves at the southern end of our latitudinal gradient (at 60°N) but smaller than intact leaves at its northern end (at 69°N), suggesting that female oviposition preference changes with latitude. No latitudinal changes were observed in larval size, mine length or area, and in per capita food consumption, but the larval feeding efficiency (quantified as the ratio between larval size and mine size) increased with latitude. Consequently, S. lapponica larvae consumed less foliar biomass at higher latitudes than at lower latitudes to reach the same size. Based on space-for-time substitution, we suggest that climate warming will increase metabolic expenses of insect herbivores with uncertain consequences for plant–herbivore interactions.     

Stimulation of ethylene production by a cell wall component from mature green tomato fruit

Pectic (carbonate-soluble, covalently-bound pectin, CBP) material stimulated increased ethylene production when vacuum-infiltrated into whole, mature green tomato ( Lycopersicon esculentum Mill. cv. Rutgers) fruit. Activity was greatest if CBP was extracted from mature green tomatoes with jellied locules. CBP extracted from mature green tomatoes with immature seeds had no elicitor activity, while CBP from turning or red ripe tomatoes was only moderately active. Infiltration of CBP from normal mature green fruit into ripening inhibitor ( rin ) mutant tomato fruit stimulated ethylene production and attenuated red pigmentation in these fruits. Partial purification of the active material was accomplished using DEAE-Sephadex and BioGel P-100 chromatography. The most highly purified fraction is comprised of neutral carbohydrate (95%) with a relatively low content of amino acids (1%) and a uronic acid content of less than 5%. This material may be an endogenous trigger of ethylene production and ripening.     

Studies on the catalytic mechanism of H2-forming methylenetetrahydromethanopterin dehydrogenase: para-ortho H2 conversion rates in H2O and D2O

H₂–forming N ⁵,N ¹⁰ –methylenetetrahydromethanopterin dehydrogenase is a novel type of hydrogenase that contains neither nickel nor iron-sulfur clusters. Evidence has been presented that the reaction mechanism catalyzed by the enzyme is very similar to that of the formation of carbocations and H₂ from alkanes under superacidic conditions. We present here further results in support of this mechanism. It was found that the purified enzyme per se did not catalyze the conversion of para H₂ to ortho H₂, a reaction catalyzed by all other hydrogenases known to date. However, it catalyzed the conversion in the presence of the substrate N ⁵,N ¹⁰ –methenyltetrahydromethanopterin (CH≡H₄MPT⁺), indicating that for heterolytic cleavage of H₂ the enzyme-CH≡H₄MPT⁺ complex is required. In D₂O, the formation of HD and D₂ from H₂ rather than a para–ortho H₂ conversion was observed, indicating that after heterolytic cleavage of H₂ the dissociation of the proton from the enzyme-substrate complex is fast relative to the re-formation of free H₂.     

Stability of α-chymotrypsin conjugated with poly (ethylene glycols) and proxanols at high temperature and in watercosolvent mixtures

Summary -Chymotrypsin has been modified with poly(ethylene glycols) and proxanols, block-copolymers of poly(propylene oxide) and poly(ethylene oxide). These conjugates were several-fold more thermostable and showed high catalytic activity at elevated concentrations of water-miscible organic cosolvents (alcohols and dimethyl sulfoxide) which caused inactivation of free (non-modified) -chymotrypsin.     

A transposon insertion in the Arabidopsis SSR16 gene causes an embryo-defective lethal mutation

The SSR16 gene of Arabidopsis has been identified as a gene encoding a ribosomal protein S16 homolog through analysis of a transposon insertion mutation. The insertion mutation is lethal, arresting embryonic development at approximately the transition from the globular to the heart stage of embryonic development. Co-segregation of the mutant phenotype with the transposon-borne drug-resistance marker and loss of the inserted transposon concomitant with phenotypic reversion provided evidence that the transposon had caused the mutation. Sequences flanking the insertion site were amplified from DNA of viable heterozygotes by thermal asymmetric interlaced (TAIL) PCR. The amplified fragment flanking the 3' end of the inserted element was sequenced and found to be identical to an Arabidopsis expressed sequence tag (EST). The EST, in turn, contained a coding sequence homologous to the ribosomal protein S16 (RPS16) of bacteria such as Escherichia coli, Bacillus subtilis and Salmonella typhimurium , as well as Neurospora crassa mitochondria and higher plant plastids. Thus the gene identified by the embryo-defective lethal insertion mutation encodes an RPS16 homolog and has been designated the SSR16 gene.     

Size of genetic bottlenecks leading to virus fitness loss is determined by mean initial population fitness.

Genetic bottlenecks are important events in the genetic diversification of organisms and colonization of new ecological niches. Repeated bottlenecking of RNA viruses often leads to fitness losses due to the operation of Muller's ratchet. Herein we use vesicular stomatitis virus to determine the transmission population size which leads to fitness decreases of virus populations. Remarkably, the effective size of a genetic bottleneck associated with fitness loss is greater when the fitness of the parental population increases. For example, for starting virus populations with low fitness, population transfers of five-clone-to-five-clone passages resulted in a fitness increase. However, when a parental population with high fitness was transferred, 30-clone-to-30-clone passages were required simply to maintain fitness values.     

Extreme fitness differences in mammalian and insect hosts after continuous replication of vesicular stomatitis virus in sandfly cells.

Continuous, persistent replication of a wild-type strain of vesicular stomatitis virus in cultured sandfly cells for 10 months profoundly decreased virus replicative fitness in mammalian cells and greatly increased fitness in sandfly cells. After persistent infection of sandfly cells, fitness was over 2,000,000-fold greater than that in mammalian cells, indicating extreme selective differences in the environmental conditions provided by insect and mammalian cells. The sandfly-adapted virus also showed extremely low fitness in mouse brain cells (comparable to that in mammalian cell cultures). It also showed an attenuated phenotype, requiring a nearly millionfold higher intracranial dose than that of its parent clone to kill mice. A single passage of this adapted virus in BHK-21 cells at 37 degrees C restored fitness to near neutrality and also restored mouse neurovirulence. These results clearly illustrate the enormous capacity of RNA viruses to adapt to changing selective environments.