Biology subjects

Hofmann, G.

Publications and source records attributed to Hofmann, G..

4 recordsLinked to original sources

bioRxiv2026

A Scalable, High-Throughput Optomotor Response Pipeline for Quantitative Analysis of Vision Using Infinity-Pools

The optomotor response (OMR) provides a robust readout assay for evaluating visually guided locomotion and has been widely applied to various animal models. We present a scalable, high-throughput OMR platform with tuneable and moving stripe patterns simultaneously projected to the side of 50 petri dishes. The setup is optimized for hatchling-stage medaka (Oryzias latipes and Oryzias sakaizumii) and larval stage zebrafish (Danio rerio) and integrates custom software for automated generation of visual stimuli and specimen detection, enabling precise and automated quantification of optomotor behaviour across thousands of individuals. Using this platform, we systematically assess the visual performance of zebrafish and five medaka strains. By varying stripe width, direction, speed, contrast, and colour, we address spatial resolution, contrast, and colour sensitivity. Albino mutant medaka exhibited the highest sensitivity, responding at lower stripe widths and across a broader range of contrasts and chromatic conditions. Interestingly, some Cab and HO5 hatchlings displayed uni-directional response, revealing strain-specific visuomotor differences. Our platform enables reliable detection of OMR behaviour already at hatching and supports robust analysis of visuomotor function. The modular design, automated detection, analysis pipeline, and capacity for large sample numbers make it a powerful tool for comparative vision research, high-throughput genetic screening, and systematic behavioural profiling.

animal behavior and cognition↗

bioRxiv2024

Genomic signatures of coral adaptation and recovery following a mass mortality event

Globally, corals face an increased frequency of mass mortality events (MMEs) as populations experience repeated marine heatwaves which disrupt their obligate algal symbiosis. Despite greater occurrences of MMEs, the relative roles of the environment, host, and symbiont genetic variation in survival and recovery remain unresolved. We explore these roles using high-resolution temporal and spatial whole genome sequencing of corals before, after, and several years following a MME. We show that host genetics has an impact on bleaching and mortality and that selected alleles important for adaptation persist through the next generation. We also demonstrate that survival for the bleaching event was highly polygenic and that allele frequency shifts have reef habitat specificity. This study reveals how MMEs reshape the genomic landscape and the spatial and temporal distribution of genomic diversity within coral populations facing severe threats from global change. SIGNIFICANCEInvestigations of natural selection in coral genomes following bleaching events have primarily relied on indirect inference, using contemporary populations to explore signatures of past selective pressures, or failed to link these events to the subsequent generation. This has left an open question about the ability of a coral population to adapt from host standing genetic variation in the face of a bleaching event. We demonstrate rapid evolution in a Moorean coral population following an MME from a marine heatwave by capturing allele frequency shifts through time. However, the complex polygenic architecture of bleaching survival shows strong habitat specificity, complicating the path towards a genomic prediction of bleaching.

evolutionary biology↗

bioRxiv2024

Characterizing medaka visual features using a high-throughput optomotor response assay

Medaka fish (Oryzias latipes) is a powerful model to study genetics underlying the developmental and functional traits of the vertebrate visual system. We established a simple and high-throughput optomotor response (OMR) assay utilizing medaka larvae to study visual functions including visual acuity and contrast sensitivity. Our assay presents multiple adjustable stripes in motion to individual fish in a linear arena. For that the OMR assay employs a tablet display and the Fish Stripes software to adjust speed, width, color, and contrast of the stripes. Our results demonstrated that optomotor responses were robustly induced by black and white stripes presented from below in the linear-pool-arena. We detected robust strain specific differences in the OMR when comparing long established medaka inbred strains. We observed an interesting training effect upon the initial exposure of larvae to thick stripes, which allowed them to better respond to narrower stripes. The OMR setup and protocol presented here provide an efficient tool for quantitative phenotype mapping, addressing visual acuity, trainability of cortical neurons, color sensitivity, locomotor response, retinal regeneration and others. Our open-source setup presented here provides a crucial prerequisite for ultimately addressing the genetic basis of those processes.

animal behavior and cognition↗

bioRxiv2021

SPIRO-the automated Petri plate imaging platform designed by biologists, for biologists

Phenotyping of model organisms grown on Petri plates is often carried out manually, despite the procedures being time-consuming and laborious. The main reason for this is the limited availability of automated phenotyping facilities, whereas constructing a custom automated solution can be a daunting task for biologists. Here, we describe SPIRO, the Smart Plate Imaging Robot, an automated platform that acquires time-lapse photos of up to four vertically oriented Petri plates in a single experiment, corresponding to 192 seedlings for a typical root growth assay and up to 2500 seeds for a germination assay. SPIRO is catered specifically to biologists needs, requiring no engineering or programming expertise for assembly and operation. Its small footprint is optimized for standard incubators, the inbuilt green LED enables imaging under dark conditions, and remote control provides access to the data without interfering with sample growth. SPIROs excellent image quality is suitable for automated image processing, which we demonstrate on the example of seed germination and root growth assays. Furthermore, the robot can be easily customized for specific uses, as all information about SPIRO is released under open-source licenses. Importantly, uninterrupted imaging allows considerably more precise assessment of seed germination parameters and root growth rates compared to manual assays. Moreover, SPIRO enables previously technically challenging assays such as phenotyping in the dark. We illustrate the benefits of SPIRO in proof-of-concept experiments which yielded a novel insight on the interplay between autophagy, nitrogen sensing and photoblastic response.

plant biology↗