Elastomeric micropillar arrays for the study of protrusive forces in hyphal invasion

Fungi and Oomycetes are microorganisms that can be pathogenic and grow invasively causing significant economic losses and diseases1. • These organisms grow by extending the cell at the tip. This involves turgor pressure, cell wall yielding and a dynamic cytoskeleton, giving rise to a protrusive force2,3. •A Lab-on-a-Chip platform, with integrated force sensor based on elastomeric micro-pillars, is allowing us to study the molecular mechanisms which enable the generation of protrusive force at the tip of invasively-growing hyphae. •A maximum force of 16 μN was measured for the oomycete Achlya bisexualis cultured on the chip

Microfluidic Platform to Study Electric Field Based Root Targeting by Pathogenic Zoospores

This paper reports the fabrication and application of a microfluidic Lab-on-a-Chip platform to study the electrotactic movements of pathogenic microorganisms. The movement of the pathogens in response to electric fields are one way in which they are thought to locate their hosts. Design and fabrication of the platform, and associated micro-electronics are described. The platform contains arrays of micro-electrodes that generate an electric field of defined strength in a micro-chamber into which feed inlet and outlet channels for entry and exit of media and microorganisms. To demonstrate applicability of the platform, motile zoospores of the pathogenic oomycete Phytophthora nicotianae were seeded in the inlet and a voltage was applied to investigate the electrotactic responses of the zoospores. This platform offers a unique opportunity to study electrotactic movements that may be responsible for the ability of the pathogens to locate and invade host tissue

Comparative studies of ion transport in marine fungi

SIGLEAvailable from British Library Document Supply Centre- DSC:DX97347 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Bioactivity of ethanol extracts from Eucalyptus bosistoana F. Muell. heartwood

Variability in bioactivity and chemical composition of Eucalyptus bosistoana F. Muell. heartwood extracts between individual trees from two different sites were investigated. Combining the results of fungal assays and quantitative gas chromatography (GC) of the extracts allowed the investigation of bioactive compounds. The bioactivity of extracts was assessed against white rot (Trametes versicolor [L.] Lloyd) and brown rot (Coniophora cerebella Pers.). Ethanol extracts from E. bosistoana heartwood were less effective on the white rot than against the brown rot. Variability in the bioactivity of extracts against the two fungi was observed between the trees. A site effect in the bioactivity was found for the white rot but not the brown rot. Bioactivity of the extracts against the white rot was not correlated to that against the brown rot. The absence of a relationship between of effects of the extracts on the relative growth rates of the white rot and the brown rot indicated that the two fungi were affected by different compounds. Thirty two compounds were quantified in E. bosistoana ethanol extracts by GC, of which six (benzoic acid, hexadecanoic acid, 1,5-dihdroxy-12-methoxy-3,3-dimethyl-3,4-dihydro-1H-anthra[2, 3-c]pyran-6,11-dione, octadecanoic acid, polyphenol and beta-sitosterol) were identified. Significant variability in eight compounds was found between the two sites. Multivariate (PLSR) analysis identified compounds at the retention times 10.2 and 11.5 min (hexadecanoic acid) to be most related to the bioactivity of the E. bosistoana heartwood extracts against white rot and brown rot

Parallel screening of single zoospore germination and germ tube protrusive forces

This paper reports the parallel screening of zoospore germination and protrusive forces of germ tubes on a labon-a-chip platform, integrating valve-based single zoospore compartmentalization with micropillar force sensing. Individually-controllable, normally-closed microvalves were optimized to facilitate zoospore compartmentalization in measurement channels containing traps and sensing pillars. Performance was evaluated using microspheres and zoospores of the oomycete Achlya bisexualis. By parallelizing the screening, the platform will support fundamental studies and aid in the discovery of new compounds to control fungal and oomycete pathogens

Student application for special consideration for examination performance following a natural disaster

Universities have a long-established tradition of granting students special consideration when circumstances beyond their control negatively affect performance in assessments. Typically, such situations affect only one student (e.g. medical emergencies) but we consider the impact of a natural disaster that led to all students being eligible for special consideration on a single assessment. Students did not have to get applications for special consideration endorsed by a qualified professional but were able to rate their own level of impairment. Our findings indicated that students were impaired in their performance and accordingly application for special consideration was warranted. Those few students who did not submit an application were disadvantaged relative to their peers. There was little relationship between the students’ self-reported levels of impairment and their performance, but those who considered themselves seriously impaired were disproportionately unlikely to complete the assessment. Those with poorer grades leading into the final assessment were no more likely to request special consideration. Although our observations were with an unusual example, our overall findings support the need for a special consideration policy, and indicate that students can treat such a policy appropriately and not exploit the opportunity to obtain unmerited advantage

Fabrication of In-Channel High-Aspect Ratio Sensing Pillars for Protrusive Force Measurements on Fungi and Oomycetes

© 1992-2012 IEEE. This paper reports the fabrication and application of a Lab-on-a-Chip platform containing single-elastomeric micropillars in channel constrictions, which enable the measurement of protrusive forces exerted by individual fungal hyphae. We show the device design, the fabrication process, and photoresist optimization required to adapt the microfluidic platform to relatively thin hyphae. To demonstrate the applicability of the devices, the oomycete Achlya bisexualis and the fungus Neurospora crassa were cultured on PDMS chips. Devices were combined with confocal imaging to study the interaction of A. bisexualis hyphae with the measurement pillars. The force exerted by individual hyphae of N. crassa was measured and compared with a hyphal growth rate and diameter. The platform provides a new tool to help understand the molecular processes that underlie protrusive growth and this may present new ways to tackle the pathogenic growth of these organisms and thus combat the loss of diversity that they cause. This paper is based on the conference proceedings presented at the 31st IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2018), Belfast. [2018-0090

A monolithic polydimethylsiloxane platform for zoospore Capture, germination and single hypha force sensing

This paper reports a triple-layer, polydimethylsiloxane (PDMS)-based lab-on-a-chip platform combining the capture and culture of individual oomycete zoospores with integrated force sensing on germinated hyphae. The platform enables the concurrent study of cell-to-cell variability in hyphal growth and protrusive force generation. To demonstrate the applicability of the platform, individual zoospores of the oomycete Achlya bisexualis were trapped by a constriction structure, cultured on the device and the micro-Newton forces exerted by hyphae measured by tracking the deflection of elastomeric micropillars. The platform provides a new tool to help understand protrusive growth on a single cell level