Characteristics of leaf rust fungi of temperate cereals and their host relationships

This thesis describes work carried out mainly on the uredinial stage of the leaf rust fungi of temperate cereals, comprising the brown rusts of barley, rye and wheat as well as oat crown rust and the wheat and barley yellow rusts.The taxonomic position of these pathogens was investigated in colony growth studies carried out under controlled conditions, with an emphasis on characters which were independant of cereal host factors. A clear morphological distinction could be made between oat crown rust, wheat brown rust, barley brown rust, rye brown rust and the yellow rusts of wheat and barley. However, no distinction apart from the host range could be made between wheat and barley yellow rust.In culture experiments the isolates were tested for their ability to grow on detached leaves of their host plants, and some of the isolates were used in axenic culture studies. All the isolates showed identical virulence patterns on detached leaves as on whole host plants. None of the isolates tested could be maintained in axenic culture.Cytogenetical characteristics were studied in some of the rust isolates. The dikaryotic binucleate condition prevailed in all isolates up to the stage of stomatal penetration. Attempts to obtain hybridisation between different races of wheat yellow rust failed.Quantitative aspects of colony growth and development were investigated in a series of studies in controlled conditions.Differences in response to inoculum density were observed in experiments with barley brown rust and yellow rust and were related to the different patterns of epidemic development of these two species. The colony growth patterns of the cereal leaf rusts in host and non-host relationships showed strong host preference. However, unexpected colony development occurred in some of the pathogen/non-host combinations

Plant Health and How it Affects Private Gardens: Experience from a Botanic Garden Pathologist

Like many other botanic gardens the Royal Botanic Garden Edinburgh (RBGE) provides advice about plant pests and diseases to amateur gardeners. This paper summarises the main problem plant categories (such as trees and vegetables), plant problems (such as pests or fungal infection) and other observations, such as number of enquiries by month noted by pathology staff at the Garden over the last twenty years

Alkaloids from the Sponge Stylissa carteri Present Prospective Scaffolds for the Inhibition of Human Immunodeficiency Virus 1 (HIV-1).

The sponge Stylissa carteri is known to produce a number of secondary metabolites displaying anti-fouling, anti-inflammatory, and anti-cancer activity. However, the anti-viral potential of metabolites produced by S. carteri has not been extensively explored. In this study, an S. carteri extract was HPLC fractionated and a cell based assay was used to evaluate the effects of HPLC fractions on parameters of Human Immunodeficiency Virus (HIV-1) infection and cell viability. Candidate HIV-1 inhibitory fractions were then analyzed for the presence of potential HIV-1 inhibitory compounds by mass spectrometry, leading to the identification of three previously characterized compounds, i.e., debromohymenialdisine (DBH), hymenialdisine (HD), and oroidin. Commercially available purified versions of these molecules were re-tested to assess their antiviral potential in greater detail. Specifically, DBH and HD exhibit a 30%-40% inhibition of HIV-1 at 3.1 μM and 13 μM, respectively; however, both exhibited cytotoxicity. Conversely, oroidin displayed a 50% inhibition of viral replication at 50 μM with no associated toxicity. Additional experimentation using a biochemical assay revealed that oroidin inhibited the activity of the HIV-1 Reverse Transcriptase up to 90% at 25 μM. Taken together, the chemical search space was narrowed and previously isolated compounds with an unexplored anti-viral potential were found. Our results support exploration of marine natural products for anti-viral drug discovery

Rapid-Survey Methods for Flowering Phenology

The Weekly Phenology Project at the Royal Botanic Garden Edinburgh has been running for three and a half years at the time of writing. Insufficient data have been collected so far for scientific analysis, but we present provisional conclusions concerning several methods of monitoring flowering behaviour. These range from objective methods, such as presence/absence of open flowers and counts of flowers or inflorescences, to non-objective methods involving assessment of the degree to which full flowering has been achieved. One monitoring method, relying on the relative numbers of flowers in the three states ‘bud’, ‘open’, and ‘gone-over’, is illustrated by the flowering behaviour of ‘simultaneously’ and ‘sequentially’ flowering species. We conclude with a discussion of the relative values of the different methods

Taxonomy based on science is necessary for global conservation

Peer reviewe

EUREC⁴A

The science guiding the EUREC⁴A campaign and its measurements is presented. EUREC⁴A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC⁴A marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or the life cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso- (200 km) and larger (500 km) scales, roughly 400 h of flight time by four heavily instrumented research aircraft; four global-class research vessels; an advanced ground-based cloud observatory; scores of autonomous observing platforms operating in the upper ocean (nearly 10 000 profiles), lower atmosphere (continuous profiling), and along the air–sea interface; a network of water stable isotopologue measurements; targeted tasking of satellite remote sensing; and modeling with a new generation of weather and climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EUREC⁴A explored – from North Brazil Current rings to turbulence-induced clustering of cloud droplets and its influence on warm-rain formation – are presented along with an overview of EUREC⁴A's outreach activities, environmental impact, and guidelines for scientific practice. Track data for all platforms are standardized and accessible at https://doi.org/10.25326/165 (Stevens, 2021), and a film documenting the campaign is provided as a video supplement

EUREC⁴A

The science guiding the EUREC⁴A campaign and its measurements is presented. EUREC⁴A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC⁴A marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or the life cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso- (200 km) and larger (500 km) scales, roughly 400 h of flight time by four heavily instrumented research aircraft; four global-class research vessels; an advanced ground-based cloud observatory; scores of autonomous observing platforms operating in the upper ocean (nearly 10 000 profiles), lower atmosphere (continuous profiling), and along the air–sea interface; a network of water stable isotopologue measurements; targeted tasking of satellite remote sensing; and modeling with a new generation of weather and climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EUREC⁴A explored – from North Brazil Current rings to turbulence-induced clustering of cloud droplets and its influence on warm-rain formation – are presented along with an overview of EUREC⁴A's outreach activities, environmental impact, and guidelines for scientific practice. Track data for all platforms are standardized and accessible at https://doi.org/10.25326/165 (Stevens, 2021), and a film documenting the campaign is provided as a video supplement

Aqueous Extracts of the Marine Brown Alga Lobophora variegata Inhibit HIV-1 Infection at the Level of Virus Entry into Cells

In recent years, marine algae have emerged as a rich and promising source of molecules with potent activities against various human pathogens. The widely distributed brown alga Lobophora variegata that is often associated with tropical coral reefs exerts strong antibacterial and antiprotozoal effects, but so far has not been associated with specific anti-viral activities. This study investigated potential HIV-1 inhibitory activity of L. variegata collected from different geographical regions, using a cell-based full replication HIV-1 reporter assay. Aqueous L. variegata extracts showed strong inhibitory effects on several HIV-1 strains, including rug-resistant and primary HIV-1 isolates, and protected even primary cells (PBMC) from HIV-1-infection. Anti-viral potency was related to ecological factors and showed clear differences depending on light exposition or epiphyte growth. Assays addressing early events of the HIV-1 replication cycle indicated that L. variegata extracts inhibited entry of HIV-1 into cells at a pre-fusion step possibly by impeding mobility of virus particles. Further characterization of the aqueous extract demonstrated that even high doses had only moderate effects on viability of cultured and primary cells (PBMCs). Imaging-based techniques revealed extract effects on the plasma membrane and actin filaments as well as induction of apoptosis at concentrations exceeding EC50 of anti-HIV-1 activity by more than 400 fold. In summary, we show for the first time that L. variegata extracts inhibit HIV-1 entry, thereby suggesting this alga as promising source for the development of novel HIV-1 inhibitors