Biology subjects

Nolte, T.

Publications and source records attributed to Nolte, T..

9 recordsLinked to original sources

bioRxiv2026

Fertilization offsets the maternal age effect on mouse oocytes provided the oviduct is not itself aged

Advanced maternal age compromises oocyte quality, and it is widely assumed that these deficits are transmitted to embryos. However, because most studies rely on in vivo conception, it has been difficult to separate the effects of oocyte aging from those of an aged fertilization environment. In aging mice, we observed that the fraction of ovulated oocytes forming implantation sites after in vivo conception fell ~3.7-fold, raising the question of whether this was due to reduced fertilization, reduced embryo quality or reduced support from the aged reproductive tract. Therefore we fertilized oocytes of aged and young mice in vitro with a shared young-donor sperm preparation, holding the fertilization environment constant and removing paternal variability. Hallmarks of maternal age were largely offset following fertilization in vitro: aged oocytes produced blastocysts at rates comparable to young controls, with altered - but not deficient - cell-lineage composition and no detectable impairment in development to term (E18.5) after transfer to young oviducts. Proteomic analysis revealed that, unlike the transcriptomic signature, the proteomic age signature of oocytes was not faithfully propagated to the blastocyst: for a subset of proteins, particularly those depleted in aged oocytes, the direction of the age effect reversed between oocyte and blastocyst. Comparison with parthenogenetically activated oocytes showed this divergence to be fertilization-dependent, implicating fertilization - rather than mere embryonic cleavage - as the driver of proteomic change. Stable-isotope labelling in live embryos showed that blastocysts from aged, fertilized oocytes both synthesized more new protein and retained less maternal protein than young counterparts; neither effect was detectable after parthenogenesis. Puromycin labelling, by contrast, showed a maternal-age-associated rise in bulk synthesis regardless of route. Together, these results indicate that the maternal-age effect on the oocyte proteome is labile rather than fixed and can be offset by fertilization itself, provided the maternal environment is not itself aged.

developmental biology↗

bioRxiv2026

Temporal-difference valence-partitioned Bayesian brains work out whether others are caring or uncaring

Working out whether others care for us is crucial in personal relationships and when seeking professional help. It is often most difficult for those most in need, e.g. following interpersonal traumata. Here, we introduce a simple Caring Attributions task and elucidate key computational mechanisms involved and, using EEG, the cortical activity representing the degree of belief that another is beneficent or maleficent. We find evidence for a new type of neurocomputational processing: valence-partitioned temporal-difference inference (TD-Bayes). This employs primary processing about latent causes, but also separate channels to represent these different valenced attributions, inspired by value-partitioned associative learning (VPAL). TD-Bayes uses slow propagation of beliefs using temporal-difference updating. These models gave a very good account of behaviour, slightly better than VPAL, but crucially, their partitioned representations have stronger, distinct representations in ERP signals. They provide a promising inroad into the understanding of how people may jump to atttibutions about caring vs. uncaring others.

neuroscience↗

bioRxiv2025

A novel and critical role of the intracellular Zona Pellucida protein 2 (ZP2) for blastocyst formation in mice

The zona pellucida (ZP) is the quintessential extracellular structure of mammalian oocytes. Contrary to long-standing view that the synthesis of ZP proteins is specific to oocytes and muted in embryos, we report here that the major zona pellucida protein ZP2 is re-synthesized and functionally required during mouse embryo development. The orthogonal methods of mass spectrometry and monoclonal immunofluorescence revealed an increase of ZP2 abundance at the 8-cell / morula stage, which did not occur when zygotes were microinjected with translation-blocking oligonucleotides (morpholinos). To shed light on the functional significance of embryonic ZP2, we performed protein knockdown using immunodepletion (by Trim-Away) while at the same time preventing replenishment (by translation-blocking morpholino). ZP2 knockdown resulted in morula stage retardation and formation of defective blastocysts, whose cell lineages trophectoderm and primitive endoderm were smaller and less able to support post-implantation development. The transcriptional correlates of these morphological alterations had a gene ontology (biological process) signature that included cell lineage-relevant terms ( endoderm development, gastrulation), while the proteomic correlates had a gene ontology signature related to protein synthesis. Taken together, these results call into question the traditional model that ZP proteins function solely in the extracellular space and accompany embryogenesis as passive bystanders: on the contrary, ZP proteins also participate actively in the intracellular processes of early embryogenesis.

developmental biology↗

bioRxiv2023

First cleavage is a manifestation of the geometry of the unfertilized oocyte: implications for monozygotic twinning in mice.

A long-standing question in mammalian embryology is whether regional differences of oocyte composition matter for the properties of blastomeres receiving those regions after fertilization. A hitherto untested hypothesis is that allocation depends on the orientation of 1st cleavage. However, the orientation is influenced by the site of sperm entry, which can be almost anywhere on the membrane of oocytes when these are inseminated. This variability undermines consistency and reproducibility of studies. Therefore, we harnessed the intracytoplasmic sperm injection to impose the site of fertilization in three specific ooplasmic regions (animal pole, vegetal pole, equator) in mice. Notwithstanding this categorical distinction, after 1st cleavage, the sister blastomeres differed from each other nearly the same way, as measured by gene expression and twin blastocysts formation following 2-cell embryo splitting. We reasoned that either the oocyte territories did not matter, or their effect was obscured by other factors. To shed light on these possibilities, we immobilized the oocytes on the micromanipulation stage during sperm injection and for 24 h thereafter. Imaging revealed that the orientation of 1st cleavage, instead of varying with the fertilization site, followed the shorter diameter of the unfertilized oocyte. This led in most cases to the segregation of animal and vegetal hemispheres into the sister blastomeres of 2-cell embryos. Since one blastomere received more of the animal materials and the other blastomere more of the vegetal materials, this offers a rationale to explain the distinct properties of monozygotic twins derived from 2-cell embryos in mice.

developmental biology↗

bioRxiv2022

Intracellular fraction of zona pellucida protein 3 is required for the oocyte to embryo transition in mice

In oocyte biology the zona pellucida has long been known to operate three extracellular functions, namely, encasing the oocytes in ovarian follicles, mediating sperm-oocyte interaction and preventing premature embryo contact with maternal epithelia. The present study uncovers a fourth function that is fundamentally distinct from the other three, being critical for embryonic cell survival. Intriguingly, the three proteins of the mouse zona pellucida (ZP1, ZP2, ZP3) were found abundantly present also inside the embryo four days after fertilization, as shown by mass spectrometry, immunoblotting and immunofluorescence. Trim-away-mediated knockdown of ZPs in fertilized oocytes resulted in various grades of embryopathy: knockdown of ZP1 impeded blastocyst expansion, knockdown of ZP2 hampered the 2nd zygotic cleavage, while knockdown of ZP3 hampered the 1st zygotic cleavage - unlike the overexpression. Transcriptome analysis of ZP3-knockdown embryos pointed at defects of cytoplasmic translation in the context of embryonic genome activation. This conclusion was supported by reduced protein synthesis in the ZP3-knockdown and by the lack of cleavage arrest when knockdown was postponed from the 1-cell to the late 2-cell stage. These data place constraints on the long-standing notion that the zona pellucida proteins only operate in the extracellular space. We postulate that such noncanonical localization of ZP3 reflect novel roles in the embryos interior during the oocyte-to-embryo transition in mice. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=171 SRC="FIGDIR/small/521410v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@18c0ca2org.highwire.dtl.DTLVardef@19168aeorg.highwire.dtl.DTLVardef@16f784forg.highwire.dtl.DTLVardef@143c4b7_HPS_FORMAT_FIGEXP M_FIG C_FIG

developmental biology↗

bioRxiv2021

The gatekeeper of Yersinia type III secretion is under RNA thermometer control

Many bacterial pathogens use a type III secretion system (T3SS) as molecular syringe to inject effector proteins into the host cell. In the foodborne pathogen Yersinia pseudotuberculosis, delivery of the secreted effector protein cocktail through the T3SS depends on YopN, a molecular gatekeeper that controls access to the secretion channel from the bacterial cytoplasm. Here, we show that several checkpoints adjust yopN expression to virulence conditions. A dominant cue is the host body temperature. A temperature of 37 {degrees}C is known to induce the RNA thermometer (RNAT)-dependent synthesis of LcrF, a transcription factor that activates expression of the entire T3SS regulon. Here, we uncovered a second layer of temperature control. We show that another RNAT silences translation of the yopN mRNA at low environmental temperatures. The long and short 5-untranslated region of both cellular yopN isoforms fold into a similar secondary structure that blocks ribosome binding. The hairpin structure with an internal loop melts at 37 {degrees}C and thereby permits formation of the translation initiation complex as shown by mutational analysis, in vitro structure probing and toeprinting methods. Importantly, we demonstrate the physiological relevance of the RNAT in the faithful control of type III secretion by using a point-mutated thermostable RNAT variant with a trapped SD sequence. Abrogated YopN production in this strain led to unrestricted effector protein secretion into the medium, bacterial growth arrest and delayed translocation into eukaryotic host cells. Cumulatively, our results show that substrate delivery by the Yersinia T3SS is under hierarchical surveillance of two RNATs. Author summaryTemperature serves as reliable external cue for pathogenic bacteria to recognize the entry into or exit from a warm-blooded host. At the molecular level, a temperature of 37 {degrees}C induces various virulence-related processes that manipulate host cell physiology. Here, we demonstrate the temperature-dependent synthesis of the secretion regulator YopN in the foodborne pathogen Yersinia pseudotuberculosis, a close relative of Yersinia pestis. YopN blocks secretion of effector proteins through the type III secretion system unless host cell contact is established. Temperature-specific regulation relies on an RNA structure in the 5-untranslated region of the yopN mRNA, referred to as RNA thermometer, which allows ribosome binding and thus translation initiation only at an infection-relevant temperature of 37 {degrees}C. A mutated variant of the thermosensor resulting in a closed conformation prevented synthesis of the molecular gatekeeper YopN and led to permanent secretion and defective translocation of virulence factors into host cells. We suggest that the RNA thermometer plays a critical role in adjusting the optimal cellular concentration of a surveillance factor that maintains the controlled translocation of virulence factors.

microbiology↗

bioRxiv2020

Study of flow effects on temperature-controlled radio-frequency ablation using phantom experiments and forward simulations

PurposeBlood perfusion is known to add variability to hepatic radiofrequency ablation (RFA) treatment outcomes. Simulation-assisted treatment planning taking into account blood perfusion may solve this problem in the future. Hence, this study aims to study perfusion effects on RFA in a controlled environment and to compare the outcome to a prediction made using finite volume simulations. MethodsAblation zones were induced in tissue-mimicking, thermochromic ablation phantoms with a single flow channel, using a RF generator with needle temperature controlled power delivery and a monopolar needle electrode. Channel radius and saline flow rate were varied and the impact of saline flow on the ablated cross-sectional area, on a potential occurrence of directional effects as well as on the delivered generator power input was studied. Finite-volume simulations reproducing the experimental geometry, flow conditions and generator power input were conducted in a second step and compared to the experimental ablation outcomes. ResultsVessels of different radii affected the ablation result in different manners. For the channel radius of 0.275 mm both the ablated area and energy input reduced with increasing flow rate. For radius 0.9 mm the ablated area reduced with increasing flow rate but the energy input increased. An increasing area and energy input were observed towards larger flow rates for the channel radius of 2.3 mm. Directional effects, i.e., shrinking of the lesion upstream of the needle and an extension thereof downstream, were observed only for the smallest channel radius. The simulations qualitatively confirmed these observations. When using the simulations to make a prediction of ablation outcomes with flow, the mean absolute error between experimental and predicted ablation outcomes was reduced from 23% to 12% as compared to neglecting flow effects. ConclusionSimulations can improve the prediction of RFA ablation regions in the presence of various blood flow effects. Our findings therefore underline the potential of simulation-assisted, patient-individual RFA treatment planning and guidance for the prediction of RFA outcomes in the presence of blood flow. Additional comments-Teresa Nolte and Nikhil Vaidya contributed equally to this work. -Volkmar Schulz and Karen Veroy contributed equally to this work. -A single reference experiment, i.e., not using a flow channel, and the image in the upper left corner of Figure 4 were included into a publication submitted to Int. J. Hyperthermia for model validation purposes. O_FIG O_LINKSMALLFIG WIDTH=178 HEIGHT=200 SRC="FIGDIR/small/172957v1_fig4.gif" ALT="Figure 4"> View larger version (122K): org.highwire.dtl.DTLVardef@935182org.highwire.dtl.DTLVardef@1cc4eedorg.highwire.dtl.DTLVardef@51ad9aorg.highwire.dtl.DTLVardef@5c9625_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFig. 4C_FLOATNO Experimentally obtained ablation zones for all RFA experiments and the corresponding reference experiments. The experimental and simulated 70{degrees}C temperature contours are marked by a blue and a black line, respectively. The ablation needle was inserted from the left side. Saline flow was established from right to left through the flow channel located below the ablation area. Radius and flow rate for each experiment were as specified within the figure below the ablation zones. In four experiments, the experimental ablation zone shows an unexpected bump structure, which we marked by white arrows. The numbering of the experiments refers to Table 1. C_FIG

biophysics↗

bioRxiv2018

Sensitivity to Affective Touch Depends on Adult Attachment Style

Affective touch supports affiliative bonds and social cognition. However, it remains unknown whether pre-existing models of social relating influence the perception of affective touch. Here, we present the first study (N=44) to examine how individual differences in attachment styles relate to the perception of affective touch, as well as to a different non-social modality of interoception, namely cardiac perceived accuracy. Using the gold standard assessment of adult attachment (Adult Attachment Interview), we found that insecure attachment was associated with reduced pleasantness discrimination between affective vs. non-affective, neutral touch. Acknowledging the different traditions in measuring attachment, we also used a well-validated self-report questionnaire that pertains to explicit representations of current close relationships. Using this measure, we found that higher scores on an attachment anxiety dimension (but not an attachment avoidance) were associated with reduced pleasantness discrimination between affective vs. non-affective, neutral touch. Attachment patterns (in both measures) were not related to cardiac perception accuracy. These results corroborate and extend previous literature on the affectivity of touch and its relation with affiliative bonds and social cognition. Given that attachment was not related to perceived cardiac accuracy, these findings point to the specificity of the relationship between affective touch and attachment.

neuroscience↗

bioRxiv2017

Value Encoding in the Globus Pallidus: fMRI reveals an interaction effect between reward and dopamine drive

The external part of the globus pallidus (GPe) is a core nucleus of the basal ganglia (BG) whose activity is disrupted under conditions of low dopamine release, as in Parkinsons disease. Current models assume decreased dopamine release in the dorsal striatum results in deactivation of dorsal GPe, which in turn affects motor expression via a regulatory effect on other nuclei of the BG. However, recent studies in healthy and pathological animal models have reported neural dynamics that do not match with this view of the GPe as a relay in the BG circuit. Thus, the computational role of the GPe in the BG is still to be determined. We previously proposed a neural model that revisits the functions of the nuclei of the BG, and this model predicts that GPe encodes values which are amplified under a condition of low striatal dopaminergic drive. To test this prediction, we used an fMRI paradigm involving a within-subject placebo-controlled design, using the dopamine antagonist risperidone, wherein healthy volunteers performed a motor selection and maintenance task under low and high reward conditions. ROI-based fMRI analysis revealed an interaction between reward and dopamine drive manipulations, with increased BOLD activity in GPe in a high compared to low reward condition, and under risperidone compared to placebo. These results confirm the core prediction of our computational model, and provide a new perspective on neural dynamics in the BG and their effects on motor selection and motor disorders.

neuroscience↗