Biology subjects

Jeschke, M.

Publications and source records attributed to Jeschke, M..

5 recordsLinked to original sources

bioRxiv2026

Antibacterial activity of a newly identified phage-derived endolysin and its parental bacteriophage against clinical uropathogenic Escherichia coli

The increasing prevalence of antibiotic-resistant uropathogenic Escherichia coli highlights the need for antibacterial strategies that can complement or extend beyond conventional antibiotic treatment. Bacteriophages and phage-derived lytic enzymes represent promising alternatives because of their distinct mechanisms of bacterial killing and their potential activity against drug-resistant pathogens. In this study, we characterized the newly discovered UPEC-infecting bacteriophage vB-EcoS_57-3 and the endolysin 57_3Lys, encoded by this phage, combining genomic, structural, and functional approaches. The phage demonstrated lytic activity against clinical UPEC isolates and retained antibacterial potential under conditions relevant to the urinary tract. Genomic and sequence analyses revealed distinctive features of 57_3Lys associated with signal-anchor-release endolysins and suggested a less common mode of intracellular translocation and activation. Functional experiments supported the involvement of the bacterial secretion machinery in endolysin-mediated lysis. Notably, the purified enzyme also displayed antibacterial activity against intact clinical E. coli cells, despite the intrinsic barrier presented by the Gram-negative cell envelope. Although this activity developed slowly, it significantly reduced both bacterial culture turbidity and viable cell number. Together, these findings provide new insights into the antimicrobial strategies based on the phages and their phage lytic enzymes, supporting further exploration of vB-EcoS_57-3 and 57_3Lys as potential tools against antibiotic-resistant UPEC.

microbiology↗

bioRxiv2025

Learning to avoid collisions: Bees use cues perceived before and after a collision to prevent negative consequences during navigation in cluttered areas

Bumblebees navigate complex environments where collisions with obstacles can impair flight performance. While bees possess innate collision avoidance reflexes, they may benefit from learning to identify and avoid high-risk collision areas using environmental cues. However, the temporal dynamics of how bees form associations between visual cues and collision experiences remain unclear. We investigated whether bumblebees associate visual cues perceived before or after collision events with a movement direction. Individual foragers were trained to navigate through a flight tunnel containing a transparent barrier and an LED panel that switched colours immediately after the bees first collision. Following training, we tested bees responses to each colour cue without the barrier. Bees demonstrated significant preferences for avoiding the previously blocked side when presented with either the pre-collision colour (81% correct responses) or post-collision colour (71% correct responses), while showing no preference when no colour cue was presented. Individual analysis revealed that 61% of bees responded to both cue types, while others showed selective responses to specific temporal windows. These results demonstrate that bees can form associations with visual cues encountered in different time windows relative to negative experiences, revealing temporal flexibility in associative learning that contributes to successful navigation in cluttered environments.

animal behavior and cognition↗

bioRxiv2025

Navigating in clutter: How bumblebees optimize flight behaviour through experience

Bumblebees are excellent navigators that travel long distances while retracing paths to known locations. They forage not only in open terrains but also in cluttered environments where obstacles force them to deviate from direct paths. This study investigates the underexplored aspect of how bees become experienced foragers and optimize flight behaviour in cluttered terrains. We recorded flight trajectories of novice bees inexperienced in navigating cluttered environments and monitored their behavioural performance as they gained experience on subsequent foraging trips through numerous obstacles. By controlling for experience levels, we analysed how flight characteristics evolve with increasing expertise. Successful navigation in cluttered terrains requires avoiding collisions with obstacles. This is only possible if these can be detected by visual features such as the retinal displacement of contrast edges. Obstacles which are harder to detect and to avoid by the bees can affect their flight performance. By introducing transparent objects into our dense environment, we challenged collision avoidance and learning mechanisms, analysing their impact on flight optimization under different environmental conditions. Our findings reveal that experienced bees fly similar paths through clutter and quickly adapt their flight regardless of their training environment. However, the specific paths followed are influenced by environmental conditions. Transparent objects primarily affect naive bees flight patterns while having minimal impact on flight optimization, suggesting that the efficient flights of experienced bees result not solely from reflexive collision avoidance but from learning and previous experience in cluttered environments.

animal behavior and cognition↗

bioRxiv2021

Thalamocortical and intracortical contributions to stimulus-evoked and oscillatory activity in rodent primary auditory cortex

Intracortical, horizontal connections seem ideally suited to contribute to cortical processing by spreading information across cortical space and coordinating activity between distant cortical sites. In sensory systems experiments have implicated horizontal connections in the generation of receptive fields and have in turn led to computational models of receptive field generation that rely on the contribution of horizontal connections. Testing the contribution of horizontal connections at the mesoscopic level has been difficult due to the lack of a suitable method to observe the activity of intracortical horizontal connections. Here, we develop such a method based on the analysis of the relative residues of the cortical laminar current source density reconstructions. In the auditory cortex of Mongolian gerbils, the method is then tested by manipulating the contribution of horizontal connections by surgical dissection. Our results indicate that intracortical horizontal connections contribute to the frequency-tuning of mesoscopic cortical patches. Futhermore, we dissociated a type of cortical gamma oscillation based on horizontal connections between mesoscopic patches from gamma oscillations locally generated within mesoscopic patches. The data further imply that global and local coordination of activity during sensory stimulation occur in a low and high gamma frequency band, respectively. Taken together the present data demonstrate that intracortical horizontal connections play an important role in generating cortical feature tuning and coordinate neuronal oscillations across cortex.

neuroscience↗

bioRxiv2020

Acute and long-term circuit-level effects in the auditory cortex after sound trauma

Harmful environmental sounds are a prevailing source for chronic hearing impairments, including noise induced hearing loss, hyperacusis, or tinnitus. How these symptoms are related to pathophysiological damage to the sensory receptor epithelia and its effects along the auditory pathway, such as functional reorganizations in the auditory cortex (ACx), have been documented in numerous studies. An open question concerns the temporal evolution of maladaptive changes after damage and their manifestation in the balance between afferent thalamocortical input and corticocortical input to the ACx. To address this, we investigated the loci of plastic reorganizations across the tonotopic axis of the auditory cortex of male Mongolian gerbils (Meriones unguiculatus) acutely after a sound trauma and after several weeks. We used a laminar residual current-source density analysis to dissociate adaptations of intracolumnar input and horizontally relayed corticocortical input to synaptic populations across cortical layers in ACx. A pure tone-based sound trauma caused acute changes of subcortical inputs and corticocortical inputs at all tonotopic regions, particularly showing a broad elimination of tone-evoked inputs at tonotopic regions with a pre-trauma best frequency between 2-8 kHz. At other cortical sites, the overall columnar activity acutely decreased, while relative contributions of lateral corticocortical inputs increased. After 4-6 weeks, cortical activity to the altered sensory inputs showed a general increase of local thalamocortical input reaching levels higher than before the trauma. Hence, our results suggest a detailed mechanism for overcompensation of altered frequency input in the auditory cortex that relies on a changing balancing of thalamocortical and intracortical input and is confined to the spectral neighborhood of the trauma frequency. Significance statementHarmful noise exposure is a major anthropogenic cause of hearing disorders and is becoming an ever-increasing burden for human health and society. Damage to the sensory epithelia elicited by harmful sounds can subsequently lead to chronic hearing loss, hyperacusis or tinnitus. We still lack an understanding of the pathophysiological plastic processes and their evolution, particularly at the circuit level of the auditory cortex (ACx), which is fundamentally involved in auditory perception. We demonstrate that plastic changes in ACx after noise induced hearing loss (NIHL) occur over several weeks, and that changes in intracortical functional connectivity compensate the acute effects in the deafferentiated subcortical inputs. Such long-term changes may underlie the temporal evolution of hearing impairments or phantom sounds after NIHL.

neuroscience↗