Biology subjects

Geiger, N.

Publications and source records attributed to Geiger, N..

4 recordsLinked to original sources

bioRxiv2025

Context-dependent abdomen bobbing in a jumping spider: a dynamic visual signal

Anti-predatory visual signals play a key role in deterring predatory attacks, and can include crypsis, warning colors or visual mimicry. Static traits such as shape or color are well-studied, whereas locomotion-related signals remain less understood despite being particularly intriguing as they can be controlled by the animals perception of danger. In this study, we explore the potential function of a highly conspicuous dynamic behavior--abdomen bobbing--exhibited by the diurnal jumping spider Heliophanus cf. cupreus during locomotion. Due to the high conspicuousness, we hypothesized that abdomen bobbing could function as a visual signal, specifically as an anti-predatory signal. To test this hypothesis, we first analyzed the behavior and found that bobs occur almost exclusively during gait stops (98.5%) with 83.5% of gait stops entailing abdomen bobbing. We then examined its context-dependency, measuring the prevalence of abdomen bobbing under four conditions: 1) control, 2) in darkness, 3) during prey encounters, 4) during simulated conspecific encounters (i.e. mirror), and 5) during predator encounters. Abdomen bobbing was virtually absent in darkness and during prey encounters, but significantly increased during conspecific and predator encounters, suggesting active control. The increase in abdomen bobbing when confronted with a predator strongly supports an anti-predatory signaling function, potentially a form of locomotion mimicry. We equally found support for an intra-specific signaling function, which might indicate the co-option of a signal from one context (predatory) to another (conspecific). Our study opens new avenues for investigating the role of motion in both inter- and intraspecific signaling.

animal behavior and cognition↗

bioRxiv2025

Visualizing the transcription and replication of influenza A viral RNAs in cells by multiple direct RNA padlock probing and in-situ sequencing (mudRapp-seq)

Influenza A viruses (IAV) contain eight negative-sense single-stranded viral RNA (vRNA) molecules, which are transcribed into mRNA and replicated via complementary RNA (cRNA). These processes are tightly regulated, but the precise molecular mechanisms governing the switch from transcription to replication remain elusive. Here, we introduce multiple direct-RNA assisted padlock probing in combination with in situ sequencing (mudRapp-seq) to visualize the transcription and replication of all eight IAV vRNA and mRNA molecules at the single-cell level. We demonstrate that direct RNA padlock probing is three times more efficient than conventional probes that target cDNA. Individual probes showed variations in efficiency, partly due to the RNA structure of the target, which was mitigated by employing multiple padlock probes per target. Applying mudRapp-seq to an infection time course, we observed early mRNA expression, followed by vRNA accumulation approximately 3 hours later. Individual viral segments exhibited differential expression, particularly in the mRNA population. Both bulk and single-cell analyses revealed a correlation between the expression of M mRNA and the onset of the transcription-to-replication switch. Our findings demonstrate that mudRapp-seq offers significant potential for elucidating viral replication mechanisms and may be applicable to studying other RNA viruses and cellular RNA processes.

microbiology↗

bioRxiv2022

Acetylsalicylic acid and Salicylic acid inhibit SARS-CoV-2 replication in precision-cut lung slices

Aspirin, with its active compound acetylsalicylic acid (ASA), shows antiviral activity against rhino- and influenza viruses and at high concentrations. We sought to investigate whether ASA and its metabolite salicylic acid (SA) inhibit SARS-CoV-2 since it might use similar pathways to influenza viruses. The compound-treated cells were infected with SARS-CoV-2. Viral replication was analyzed by RTqPCR. The compounds suppressed SARS-CoV-2 replication in cell culture cells and in a patient-near replication system using human precision-cut lung slices by two orders of magnitude. The compounds did not interfere with viral entry but led to lower viral RNA expression after 24 h.

microbiology↗

bioRxiv2021

Towards a broad-spectrum antiviral, the myristoyltransferase inhibitor IMP-1088 suppresses viral replication - the Yellow fever NS5 is myristoylated

Although a potent Yellow fever vaccine is available since 1937, up to 200.000 severe cases are reported per year, which indicates that virus vaccines require additional support by antiviral therapies. Direct-acting antiviral drugs against severe and widespread diseases, such as DENV and Yellow fever infections with more than millions of diagnosed diseases per year, are still not available. Since antivirals development against neglected diseases is uneconomical, a broadspectrum antiviral compound would be of public benefit. Here, we show that IMP-1088, a recently published myristoyltransferase-1/2 inhibitor suppressing Rhino- and Polioviruses, inhibits replication of HIV-1, Yellow fever virus, Dengue virus, Vaccinia virus, CMV, and human Herpesvirus 8 in the low nanomolar range, indicating that IMP-1088 has broad-range activity against different pathogenic virus families. The inhibition relies on virally encoded myristoylation signals since Zika, Chikungunya, and Enterovirus 71 are not affected by IMP-1088. Furthermore, we show that the Yellow fever NS5 protein is myristoylated and IMP-1088 treatment of Dengue and Yellow fever infected cells leads to a re-localisation of the viral NS5 proteins. Author SummaryTreatment of viral diseases requires the development of tailored drugs specific to inhibit certain virus families. This specificity results in missing treatment options for important human pathogens such as Yellow fever and Dengue virus infection since the development is laborious and costly. Substances acting on various virus families could solve this problem. Here, we describe that IMP-1088, an inhibitor of the cellular myristoyltransferase, inhibits HIV-1, Dengue virus, Yellow fever viruses, Vaccinia virus, and Herpesviruses at low concentrations, which do not affect cell proliferation. Viruses without predicated myristoylation sites, such as Zika viruses, were not inhibited by IMP-1088. Since no experimental evidence was provided that Yellow fever virus proteins are myristoylated, we analysed the post-translational modification of Yellow fever NS5 protein. We determined the subcellular localisation to understand the mechanism of the IMP-1088 mediated suppression and could show that both the Dengue and the Yellow fever NS5 proteins are re-localised by IMP-1088 treatment.

microbiology↗