Biology subjects

Steiner, F.

Publications and source records attributed to Steiner, F..

7 recordsLinked to original sources

bioRxiv2026

SLBP-independent control of maternal histone mRNA

Replication-dependent (RD) histones are crucial for packaging newly replicated DNA into chromatin, ensuring genome stability. In metazoans, the mRNA of RD histones is uniquely regulated through a conserved 3' stem-loop bound by stem-loop binding protein (SLBP). This allows cell cycle-coupled regulation of these important transcripts. However, oocytes must stabilise histone mRNAs independently of the cell cycle to ensure maternal loading to support the first embryonic divisions. Using Caenorhabditis elegans as a model system, we discovered an SLBP-independent mechanism that ensures RD histone transcript stability during oogenesis. This is mediated by the protein complex PETISCO, bound to the effector protein TOST-1, which directly binds the histone stem-loop region and maintains maternal histone mRNA levels during oogenesis and early embryogenesis. Loss of this mechanism disrupts histone homeostasis, leading to premature genome activation, mitotic defects, and embryonic lethality. Interestingly, the same complex, PETISCO, acts in piRNA biogenesis when bound to the effector PID-1, revealing an intriguing co-option of this histone mRNA homeostasis mechanism by the piRNA pathway. Our findings reveal a unique SLBP-independent mechanism of histone mRNA regulation, that served as a basis for the evolution of a novel piRNA biogenesis mechanism.

molecular biology↗

bioRxiv2025

Real-time affect decoding in the amygdalo-hippocampal circuit from dynamic auditory signals

Affect decoding from auditory signals requires the temporal tracking and neural processing of dynamic sound patterns, such as in affective speech. Affective speech is commonly expressed to maximize its emotional impact and its neural decoding in integrated medial limbic circuits of recipients. Here we examined how affective speech, which was live produced by speakers to maximize amygdala-hippocampal connectivity in listeners, can evoke significant intralimbic and cortico-limbic affect decoding mechanisms. Aggressive and joyful affective speech that was produced based on real-time feedback of amygdala-hippocampal couplings in listeners increased intralimbic connectivity as well as activity in auditory cortical nodes as parts of a broader affective sound processing network. Neural time courses in the auditory cortex also correlated with acoustic patterns of adaptive speech indicative of a communicative speaker-listener coupling. Affective speech can thus meaningfully influence limbic circuit synchronizations with a specific significance of the amygdala-hippocampal circuit for affect decoding from auditory signals.

neuroscience↗

bioRxiv2024

Morphotype-specific calcium signaling in human microglia

Key functions of Ca2+ signaling in rodent microglia include monitoring the brain state or the surrounding neuronal activity and sensing the danger or damage in their vicinity. Microglial Ca2+ dyshomeostasis is a disease hallmark in many mouse models of neurological disorders but the Ca2+ signal properties of human microglia remain unknown. Using a newly developed toolbox, we analyzed in situ Ca2+ signaling of decades-old human cortical microglia. The data revealed marked compartmentalization of Ca2+ signals, with signal properties differing across the compartments and resident morphotypes. The basal Ca2+ levels were low in ramified and high in ameboid microglia. The fraction of cells with ongoing Ca2+ signaling, the fraction and the amplitude of process Ca2+ signals and the duration of somatic Ca2+ signals decreased when moving from ramified via hypertrophic to ameboid microglia. In contrast, the size of active compartments, the fraction and amplitude of somatic Ca2+ signals and the duration of process Ca2+ signals increased along this pathway.

immunology↗

bioRxiv2023

Super-Resolved FRET and Co-Tracking in pMINFLUX

Single-molecule FRET (smFRET) is widely used to investigate dynamic (bio) molecular interactions taking place over distances of up to 10 nm. With the advent of recent super-resolution methods such as MINFLUX, MINSTED or RASTMIN, the spatiotemporal resolution of these techniques advanced towards the smFRET regime. While these methods do not suffer from the spatial restriction of FRET, they only visualize one emitter at a time, thus rendering fast dynamics of interactions out of reach. Here, we describe two approaches to overcome this limitation in pMINFLUX using its intrinsic fluorescence lifetime information. First, we combined pMINFLUX with smFRET. This enabled us to track a FRET donor fluorophore and simultaneously colocalize its FRET acceptor with nanometer precision. To extend co-localized tracking beyond the FRET range, we developed pMINFLUX lifetime multiplexing, a method to simultaneously track two fluorophores with similar spectral properties but distinct fluorescence lifetimes. We demonstrated its application on both static and dynamic DNA origami systems with a precision better than 2 nm. Within the FRET range, pMINFLUX lifetime multiplexing additionally uses a novel combined phasor-microtimegating approach. This paves the way for nanometer precise co-localized tracking for inter-dye distances between 4 nm and 100 nm, closing the resolution gap between smFRET and co-tracking. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=137 SRC="FIGDIR/small/534096v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@11459forg.highwire.dtl.DTLVardef@1f1cee2org.highwire.dtl.DTLVardef@4592e6org.highwire.dtl.DTLVardef@1af3e48_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

bioRxiv2020

Trans-generational inheritance of centromere identity requires the CENP-A N-terminal tail in the C. elegans maternal germ line

Centromere protein A (CENP-A) is a histone H3 variant that defines centromeric chromatin and is essential for centromere function. In most eukaryotes CENP-A-containing chromatin is epigenetically maintained, and centromere identity is inherited from one cell cycle to the next. In the germ line of the holocentric nematode Caenorhabditis elegans, this inheritance cycle is disrupted. CENP-A is removed at the mitosis-to-meiosis transition and is established de novo on chromatin during diplotene of meiosis I. Here we show that the N-terminal tail of CENP-A is required for the de novo establishment of centromeres, but dispensable for centromere maintenance during embryogenesis. Worms homozygous for a CENP-A tail deletion maintain a functional centromere during development, but give rise to inviable offspring because they fail to re-establish centromeres in the maternal germ line. We identify the N-terminal tail of CENP-A as a critical domain for the interaction with the conserved kinetochore protein KNL-2, and argue that this interaction plays an important role in setting centromere identity in the germ line. We conclude that centromere establishment and maintenance are functionally distinct in C. elegans.

genetics↗

bioRxiv2020

Addressable Nanoantennas with Cleared Hotspots for Single-Molecule Detection on a Portable Smartphone Microscope

The advent of highly sensitive photodetectors1,2 and the development of photostabilization strategies3 made detecting the fluorescence of a single molecule a routine task in many labs around the world. However, to this day, this process requires cost-intensive optical instruments due to the truly nanoscopic signal of a single emitter. Simplifying single-molecule detection would enable many exciting applications, e.g. in point-of-care diagnostic settings, where costly equipment would be prohibitive.4 Here, we introduce addressable NanoAntennas with Cleared HOtSpots (NACHOS) that are scaffolded by DNA origami nanostructures and can be specifically tailored for the incorporation of bioassays. Single emitters placed in the NACHOS emit up to 461-fold brighter enabling their detection with a customary smartphone camera and an 8-US-dollar objective lens. To prove the applicability of our system, we built a portable, battery-powered smartphone microscope and successfully carried out an exemplary single-molecule detection assay for DNA specific to antibiotic-resistant Klebsiella pneumonia "on the road ".

biophysics↗

bioRxiv2019

Genomic signature of shifts in selection in a sub-alpine ant and its physiological adaptations

Understanding how organisms adapt to extreme environments is fundamental and can provide insightful case studies for both evolutionary biology and climate-change biology. Here, we take advantage of the vast diversity of lifestyles in ants to identify genomic signatures of adaptation to extreme habitats such as high altitude. We hypothesised two parallel patterns would occur in a genome adapting to an extreme habitat: i) strong positive selection on genes related to adaptation and, ii) a relaxation of previous purifying selection. We tested this hypothesis by sequencing the high-elevation specialist Tetramorium alpestre and four other phylogenetic related species. In support of our hypothesis, we recorded a strong shift of selective forces in T. alpestre, in particular a stronger magnitude of diversifying and relaxed selection when compared to all other ants. We further disentangled candidate molecular adaptations in both gene expression and protein-coding sequence that were identified by our genome-wide analyses. In particular, we demonstrate that T. alpestre has i) a derived level of expression for stv and other heat-shock proteins in chill shock tests, and ii) enzymatic enhancement of Hex-T1, a rate-limiting regulatory enzyme that controls the entry of glucose into the glycolytic pathway. Together, our analyses highlight the adaptive molecular changes that support colonisation of high-altitude environments.

evolutionary biology↗