Eight new monoterpene acylglucosides from Sibiraea angustata

Chemical investigation of the aqueous extract of the aerial portion of Sibiraea angustata led to the isolation of eight new monoterpene acylglucosides named sibiraglucoside A–H (1–8) and two known monoterpenes, sibiraic acid (9) and sibiskoside (10). Their structures were elucidated through extensive spectroscopic data analysis (including 1D and 2D NMR and HRESIMS experiments) and compared to literature data. In the in vitro bioassay, all of the compounds showed moderate hypolipidemic effects.     

Comparative metabolomics implicates threitol as a fungal signal supporting colonization of Armillaria luteobubalina on eucalypt roots

Armillaria root rot is a fungal disease that affects a wide range of trees and crops around the world. Despite being a widespread disease, little is known about the plant molecular responses towards the pathogenic fungi at the early phase of their interaction. With recent research highlighting the vital roles of metabolites in plant root–microbe interactions, we sought to explore the presymbiotic metabolite responses of Eucalyptus grandis seedlings towards Armillaria luteobuablina, a necrotrophic pathogen native to Australia. Using a metabolite profiling approach, we have identified threitol as one of the key metabolite responses in E. grandis root tips specific to A. luteobubalina that were not induced by three other species of soil-borne microbes of different lifestyle strategies (a mutualist, a commensalist, and a hemi-biotrophic pathogen). Using isotope labelling, threitol detected in the Armillaria-treated root tips was found to be largely derived from the fungal pathogen. Exogenous application of d- threitol promoted microbial colonization of E. grandis and triggered hormonal responses in root cells. Together, our results support a role of threitol as an important metabolite signal during eucalypt-Armillaria interaction prior to infection thus advancing our mechanistic understanding on the earliest stage of Armillaria disease development. Comparative metabolomics of eucalypt roots interacting with a range of fungal lifestyles identified threitol enrichment as a specific characteristic of Armillaria pathogenesis. Our findings suggest that threitol acts as one of the earliest fungal signals promoting Armillaria colonization of roots.     

Predicted future distribution of the African skimmer in response to a changing climate,land cover and distance from water in the mid-Zambezi Valley

Climate models project a hot and dry future for Southern Africa. In this research, Maximum Entropy was used to model the extent to which climate change, land cover and distance from water edges may influence current and future distribution of the African skimmer in the mid-Zambezi Valley. Global Biodiversity Information Facility data collected between the years 2000–2019 were used to develop the models. Three models were built: one for current distribution and two for future distribution under Representative Concentration Pathways (RCPs) 2.6 and 6.0. Results revealed that annual precipitation and distance from water edges were the most important predictors of habitat suitability for the African skimmer under current and future climate. Temperature and land cover were least important in explaining current and future distribution of the species. The RCP 2.6 predicted future decrease in suitable habitat for the African skimmer in the mid-Zambezi Valley, while RCP 6.0 predicted future increase in suitable habitat for the species. This research conclusively revealed that precipitation and distance from water edges were consistently key predictors of suitable habitat for the African skimmer.     

Spatial covariation of fish population vital rates in a stream network

Animal populations are spatially structured in heterogeneous landscapes, in which local patches with differing vital rates are connected by dispersal of individuals to varying degrees. Although there is evidence that vital rates differ among local populations, much less is understood about how vital rates covary among local patches in spatially heterogeneous landscapes. In this study, we conducted a nine-year annual mark–recapture survey to characterize spatial covariation of survival and growth for two Japanese native salmonids, white-spotted charr Salvelinus leucomaenis japonicus and red-spotted masu salmon Oncorhynchus masou ishikawae, in a headwater stream network composed of distinctly different tributary and mainstem habitats. Spatial structure of survival and growth differed by species and age class, but results provided support for negative covariation between vital rates, where survival was higher in the tributary habitat but growth was higher in the mainstem habitat. Thus, neither habitat was apparently more important than the other, and local habitats with complementary vital rates may make this spatially structured population less vulnerable to environmental change (i.e. portfolio effect). Despite the spatial structure of vital rates and possibilities that fish can exploit spatially distributed resources, movement of fish was limited due partly to a series of low-head dams that prevented upstream movement of fish in the study area. This study shows that spatial structure of vital rates can be complex and depend on species and age class, and this knowledge is likely paramount to elucidating dynamics of spatially structured populations.     

Tumour shape-dependent microwave hyperthermia using a novel coaxial micro-cut slot antenna

Given that the effectiveness of interstitial hyperthermia for cancer treatment is related to the temperature achieved during the ablation process, there is a need for an accurate understanding of the required temperature distribution which is affected by the physical shape and form of tumours. Although a maximum peak temperature value and minimum backward heating are desired, the temperature distribution needs to be not only high but also uniformly extended over a section instead of at one peak point, especially when a roughly oval-shaped tumour is aligned with the antenna. In this case, achieving a high temperature peak destroys only the central cancerous cells after the first minutes of ablation, leaving the cells on the side alive. In this paper, a complex model was extended for the study of the heat distribution of an antenna over a porous liver composed of blood, cancerous cells, and normal tissue. Three different types of antenna were analysed: single-slot, double-slot, and dipole-tip. A novel structure made up of the single-slot antenna with a micron cut, named the micro-cut slot (MCS) antenna, was proposed and analysed. Thanks to the new structure, high uniform temperature distribution with minimum backward heating was achieved. The extended model equations, which encompass a coupled nonlinear set of transient Maxwell's electromagnetic equations, extended Darcy–Brinkman equation, and local thermal non-equilibrium equations for porous medium approximation, were solved numerically using the novel alternating direction implicit, finite–difference time–domain approach. The results showed that each type of antenna could be useful if chosen according to the shape of the tumour. In comparison with previously used antennas, the MCS antenna presented a good combination of the required goals of achieving uniform high temperature distribution and minimum backward heating.     

In vitro vRNA–vRNA interactions in the H1N1 influenza A virus genome

The genome of influenza A virus consists of eight-segmented, single-stranded, negative-sense viral RNAs (vRNAs). Each vRNA contains a central coding region that is flanked by noncoding regions. It has been shown that upon virion formation, the eight vRNAs are selectively packaged into progeny virions through segment-specific packaging signals that are located in both the terminal coding regions and adjacent noncoding regions of each vRNA. Although recent studies using next-generation sequencing suggest that multiple intersegment interactions are involved in genome packaging, contributions of the packaging signals to the intersegment interactions are not fully understood. Herein, using synthesized full-length vRNAs of H1N1 WSN (A/WSN/33 [H1N1]) virus and short vRNAs containing the packaging signal sequences, we performed in vitro RNA binding assays and identified 15 intersegment interactions among eight vRNAs, most of which were mediated by the 3′- and 5′-terminal regions. Interestingly, all eight vRNAs interacted with multiple other vRNAs, in that some bound to different vRNAs through their respective 3′- and 5′-terminal regions. These in vitro findings would be of use in future studies of in vivo vRNA–vRNA interactions during selective genome packaging.