Biology subjects

Wynne, J.

Publications and source records attributed to Wynne, J..

4 recordsLinked to original sources

bioRxiv2025

Use of the Pacific oyster (Magallana gigas) as a natural sampler for the detection of Neoparamoeba perurans

Amoebic gill disease (AGD), caused by Neoparamoeba perurans, is a challenge for Atlantic salmon aquaculture. Research has, therefore, focused on detecting/monitoring N. perurans loads within/around fish pens. Recently, molecular methods to detect N. perurans have been used to reduce labour-intensive sampling, inconsistency, and stress on stock, while complimenting gill scoring and histology methods for AGD assessment. Molecular detection depends on reliable and simple sample collection, opening the possibility of using natural samplers (organisms that collect/accumulate DNA through feeding/foraging) for aquatic eDNA collection. We evaluated, through aquarium-based experiments, the utility of the Pacific oyster (Magallana gigas) to collect N. perurans DNA from the water column. In aquaria inoculated with N. perurans, total water column amoeba load decreased significantly over time in the presence of oysters. Despite this decrease no correlation between the level of amoeba accumulation within oysters and the decrease in the water column was observed. N. perurans was detected in every oyster organ type tested (mantle, gill, palp and digestive gland), though with high variation. The detection of N. perurans DNA within the digestive gland indicates that oysters ingested amoeba. Oysters were found to be viable eDNA samplers for N. perurans, providing a useful, simplified collection method.

molecular biology↗

bioRxiv2024

Reconfiguration of the visual code and retinal cell type complement in closely related diurnal and nocturnal mice

How does evolution act on neuronal populations to match computational characteristics to functional demands? We address this problem by comparing visual code and retinal cell composition in closely related murid species with different behaviours. Rhabdomys pumilio are diurnal and have substantially thicker inner retina and larger visual thalamus than nocturnal Mus musculus. High-density electrophysiological recordings of visual response features in the dorsal lateral geniculate nucleus (dLGN) reveals that Rhabdomys attains higher spatiotemporal acuity both by denser coverage of the visual scene and a selective expansion of elements of the code characterised by non-linear spatiotemporal summation. Comparative analysis of single cell transcriptomic cell atlases reveals that realignment of the visual code is associated with increased relative abundance of bipolar and ganglion cell types supporting OFF and ON-OFF responses. These findings demonstrate how changes in retinal cell complement can reconfigure the coding of visual information to match changes in visual needs.

neuroscience↗

bioRxiv2020

Using a bistable animal opsin for switchable and scalable optogenetic inhibition of neurons

There is no consensus on the best optogenetic tool for neuronal inhibition. Lamprey parapinopsin ( Lamplight) is a Gi/o-coupled bistable animal opsin that can be activated and deactivated by short and long wavelength light, respectively. Since native mechanisms of neuronal inhibition frequently employ Gi/o signalling, we asked here whether Lamplight could be used for optogenetic silencing. We show that short (405nm) and long (525nm) wavelength pulses repeatedly switch Lamplight between stable signalling active and inactive states, and that combining these wavelengths can be used to achieve intermediate levels of activity. We demonstrate that these properties can be applied to produce switchable and scalable neuronal hyperpolarisation, and suppression of spontaneous spike firing in the mouse hypothalamic suprachiasmatic nucleus. We show that expressing Lamplight in (predominantly) ON bipolar cells can photosensitise retinas following advanced photoreceptor degeneration, and that 405 and 525nm stimuli can produce responses of opposite sign in output neurons of the retina. Lamplight-driven responses to both activating (405nm) and deactivating (525nm) light can occur within 500ms and be elicited by intensities at least 10x below threshold for available inhibitory optogenetic tools. We conclude that Lamplight can co-opt endogenous signalling mechanisms to allow optogenetic inhibition that is scalable, sustained and rapidly reversible.

neuroscience↗

bioRxiv2019

Measuring vision using innate behaviours in mice with intact and impairedretina function

Measuring vision in rodents is a critical step for understanding vision, improving models of human disease, and developing therapies. Established behavioural tests for perceptual vision, such as the visual water task, rely on learning. The learning process, while effective for sighted animals, can be laborious and stressful in animals with impaired vision, requiring long periods of training. Current tests that that do not require training are based on sub-conscious, reflex responses (e.g. optokinetic nystagmus) that dont require involvement of visual cortex and higher order thalamic nuclei. A potential alternative for measuring vision relies on using visually guided innate defensive responses, such as escape or freeze, that involve cortical and thalamic circuits. In this study we address this possibility in mice with intact and degenerate retinas. We first develop automatic methods to detect behavioural responses based on high dimensional tracking and changepoint detection of behavioural time series. Using those methods, we show that visually guided innate responses can be elicited using parametisable stimuli, and applied to describing the limits of visual acuity in healthy animals and discriminating degrees of visual dysfunction in mouse models of retinal degeneration.

neuroscience↗