Biology subjects

Leesch, F.

Publications and source records attributed to Leesch, F..

3 recordsLinked to original sources

bioRxiv2025

Flickering white light stimulation at 60 Hz induces strong, widespread neural entrainment and synchrony in healthy subjects

BackgroundWhile the effects of 40 Hz externally-induced neural entrainment have been extensively described, little is known about 60 Hz entrainment in humans. Given the role of 60 Hz in cognition, neuroplasticity and neuropsychiatric disorders, this warrants further investigation. ObjectivesThis pilot study characterizes, for the first time, the neural and somatic response to 60 Hz light entrainment in healthy volunteers, over a 3 week-period. MethodsFourteen volunteers were randomized to receive either 60 Hz flickering white light or constant light as sham (30-min sessions, for 3 weeks, 5 days a week). Neural entrainment was assessed with EEG on days 1, 5 and 19. Salivary cortisol and C-reactive protein (CRP) levels, measured with ELISA, assessed the somatic response to stimulation. Side effects and well-being were monitored via questionnaires. Results60 Hz flickering light induced a strong neural entrainment across visual, parietal, temporal and frontal cortex. The signal was highly synchronous but declined significantly by day 19 compared to day 1, indicating neural habituation. Cortisol and CRP salivary levels were unchanged and the stimulation was well tolerated. ConclusionsTo the best of our knowledge this is the first study to characterize both the neural and the somatic response to flickering light over 3 weeks. The observed neural habituation suggests that neuroplasticity could be induced with repeated stimulations over 3 weeks. 60 Hz stimulation for modulating brain activity and induce neuroplasticity has implications for our basic understanding of brain physiology as well as treatment of psychiatric disorders.

neuroscience↗

bioRxiv2024

A dual ribosomal system in the zebrafish soma and germline

Protein synthesis during vertebrate embryogenesis is driven by ribosomes of two distinct origins: maternal ribosomes synthesized during oogenesis and stored in the egg, and somatic ribosomes, produced by the developing embryo after zygotic genome activation (ZGA). In zebrafish, these two ribosome types are expressed from different genomic loci and also differ in their ribosomal RNA (rRNA) sequence. To characterize this dual ribosome system further, we examined the expression patterns of maternal and somatic rRNAs during embryogenesis and in adult tissues. We found that maternal rRNAs are not only expressed during oogenesis but are continuously produced in the zebrafish germline. Proteomic analyses of maternal and somatic ribosomes unveiled differences in core ribosomal protein composition. Most nucleotide differences between maternal and somatic rRNAs are located in the flexible, structurally not resolved expansion segments. Our in vivo data demonstrated that both maternal and somatic ribosomes can be translationally active in the embryo. Using transgenically tagged maternal or somatic ribosome subunits, we experimentally confirm the presence of hybrid 80S ribosomes composed of 40S and 60S subunits from both origins and demonstrate the preferential in vivo association of maternal ribosomes with germline-specific transcripts. Our study identifies a distinct type of ribosomes in the zebrafish germline and thus presents a foundation for future explorations into possible regulatory mechanisms and functional roles of heterogeneous ribosomes.

developmental biology↗

bioRxiv2023

eIF4E1b is a non-canonical eIF4E required for maternal mRNA dormancy

Maternal mRNAs are essential for protein synthesis during oogenesis and early embryogenesis. To adapt translation to specific needs during development, maternal mRNAs are translationally repressed by shortening the polyA tails. While mRNA deadenylation is associated with decapping and degradation in somatic cells, maternal mRNAs with short polyA tails are stable. Here we report an essential role for the germline-specific paralog of the mRNA cap-binding factor eIF4E, known as eIF4E1b, in the storage and repression of maternal mRNAs with short polyA tails. eIF4E1b binds to the mRNA cap and is targeted to ribonucleoprotein complexes through its direct interaction with eIF4ENIF1/4E-T. In early embryos, eIF4E1b binds to a specific set of translationally repressed mRNAs with short or no polyA tails, such as histone mRNAs, which are translated later on during embryogenesis. Consistent with an important role in maternal mRNA dormancy, mutation of eIF4E1b in zebrafish impairs female germline development. Understanding the mechanism and function of eIF4E1B provides new insights into fundamental post-transcriptional regulatory principles governing early vertebrate development.

developmental biology↗