Biology subjects

Schmidt, V.

Publications and source records attributed to Schmidt, V..

At least 19 recordsLinked to original sources

bioRxiv2026

Decarboxylation of indoleacetic acid illuminates its evolution into a plant hormone

The evolution of indoleacetic acid (IAA) into the plant hormone auxin remains unclear. Here, we compared IAA response and metabolism in land plants and their closest living relatives, the streptophyte algae, using chemical treatments, phytohormone profiling, and targeted and untargeted metabolomics. Streptophyte algae showed neither plant-like auxin responses nor canonical IAA metabolism. Here, we demonstrate IAA side-chain decarboxylation as a novel pathway of cellular IAA metabolism, operating in streptophyte algae and land plants alike. Decarboxylation also underpinned IAA's innate photolability and yielded cytotoxic intermediates, which also accumulated endogenously under simulated sunlight. Together, these findings establish IAA decarboxylation as a major, conserved metabolic pathway, and suggest that the metabolic constraints arising from IAA's instability and indirect cytotoxicity contributed to its adoption as a plant hormone.

plant biology↗

bioRxiv2026

Linking visual and spatial exploration dynamics during free navigation in a large-scale virtual city

Balancing exploration and exploitation is a fundamental challenge for adaptive behavior, yet it remains unclear whether visual sampling and spatial locomotion reflect a single cross-domain trait or operate independently. We addressed this question by recording head-mounted eye-tracking and full-body motion tracking while 26 participants freely navigated "Westbrook", a large-scale virtual city for a total of 150 min across five sessions. From the movement trajectories we derived three spatial descriptors: median walking speed, occupancy entropy, and the proportion of explorative route choices. From the gaze data, we computed 38 robust visual descriptors encompassing fixation dynamics, pupil size, saccadic amplitude, gaze-head alignment, and transition entropy. Principal-component analysis reduced the visual descriptors to three components that captured 58 % of variance, with the first component (PC1) reflecting "gaze dynamism" (frequent shifts, larger saccades, higher transition entropy). Canonical correlation analysis revealed a strong coupling between spatial and visual behaviours: the first pair of canonical variates correlated at r = 0.68 (cross-validated r = 0.45), driven primarily by the association of high walking speed and occupancy entropy with elevated gaze dynamism. In contrast, the proportion of explorative route choices contributed little to this coupling. These findings demonstrate that individual differences in low-level locomotor speed and spatial coverage co-vary with an exploratory visual style, supporting the existence of a domain-general "exploration" factor that shapes both how people move through, and attend to, complex environments.

neuroscience↗

bioRxiv2025

Gaze Graphs in spatial navigation: visual behavior during free exploration explains individual differences in navigation performance

Vision is an important sense for spatial navigation, yet little is known about the role of visual behavior during spatial knowledge acquisition and its link to spatial navigation performance. In this study, participants freely explored the immersive virtual reality city of Westbrook while eye-tracking data were collected. Subsequently, participants spatial knowledge was tested in an immersive pointing-to-building task. To address the freedom of movement during the spatial exploration, we transformed the eye-tracking data into gaze graphs and applied a graph-theoretical analysis. We assessed gaze graph architecture and identified gaze-graph-defined landmarks, finding that their properties were consistent with key results from our earlier work. Furthermore, we investigated which factors contribute to the observed individual differences in spatial navigation performance. We found that global gaze graph measures, specifically gaze graph diameter, could explain 40% of the observed individual differences in participants mean task performance. In comparison, a model based on participants responses to a self-report questionnaire was not predictive of such differences. Consequently, we suggest that visual behavior, as reflected in global gaze graph measures, is a strong predictor of individual performance differences. Our results not only contribute to a better understanding of landmarks and individual differences in spatial navigation but also outline the potential of vision and gaze-graph-based spatial navigation research.

neuroscience↗

bioRxiv2025

PHYLOGENETIC RECLASSIFICATION OF METARHIZIUM GRANULOMATIS AND METARHIZIUM VIRIDE SPECIES COMPLEX

Metarhizium (M.) granulomatis and M. viride have previously been described as pathogens causing hyalohyphomycosis in various species of captive chameleons and bearded dragons (Pogona vitticeps). Previous studies yielded five different genotypes of M. granulomatis and four different genotypes of M. viride based on sequencing of the internal transcribed spacer1-5,8s (ITS1-5,8S) and a fragment of the large subunit of the 28S rDNA (LSU). The aim of this study was to clarify relationships between these genotypes and to obtain a more accurate phylogenetic classification by sequencing of two different loci of the RNA polymerase II second largest subunit, being referred to as RPB1 and RPB2, and the translation elongation factor 1 alpha (TEF). A total of 23 frozen isolates from 21 lizards were available for phylogenetic analysis. 13 isolates belonged to M. granulomatis-complex and 10 isolates belonged to M. viride-complex. Following the amplification and sequencing of the protein-coding genes, the resulting nucleotide sequences were analyzed, trimmed and assembled. These were further analyzed with regard to differences in single nucleotide polymorphisms (SNPs) and amino acid structure. This was complemented by the construction of phylogenetic trees. The investigation revealed no correlations between the various genotypes and the affected animal species, the isolation site or the clinical/pathological findings. With respect to the present analyses, phylogenetic reclassification is required. Three different genotypes of M. granulomatis can be distinguished, which can be phylogenetically addressed as subspecies. Six subspecies can be distinguished regarding M. viride.

molecular biology↗

bioRxiv2025

A-beta-induced distress of astrocytes triggers Alzheimer disease pathology through non-canonical delta secretase activity

The importance of astrocytes for Alzheimer disease (AD) pathology is increasingly appreciated, yet the mechanisms whereby this cell type impacts neurodegenerative processes remain elusive. In a genetic mouse model with diminished astrocyte stress response, even low levels of amyloid-{beta} trigger astrocyte reactivity, resulting in brain inflammation and massive amyloid and tau pathologies. This dysfunctional response of astrocytes to amyloid-{beta} acts through activation of {delta} secretase, a stress-induced protease implicated in both amyloid and tau-related proteolytic processing. Our findings identify a failed astrocyte stress response to amyloid-{beta} as an early inducer of amyloid and tau co-morbidity, a noxious process in AD acting through a unique non-canonical secretase pathway.

neuroscience↗

bioRxiv2024

The impact of human agents on spatial navigation and knowledge acquisition in a Virtual Environment

Concepts of spatial navigation rest on the idea of landmarks, which are immobile features or objects in the environment. However, behaviorally relevant objects or fellow humans are often mobile. This raises the question of how the presence of human agents influences spatial exploration and knowledge acquisition. Here, we investigate exploration and performance in subsequent spatial tasks within a virtual environment containing numerous human avatars. In the exploration phase, agents had a locally limited effect on navigation. They prompted participants to revisit locations with agents during their initial exploration without significantly altering overall exploration patterns or the extent of the area covered. However, agents and buildings competed for visual attention. When spatial recall was tested, pointing accuracy toward buildings improved when participants directed their attention to the buildings and nearby agents. In contrast, pointing accuracy for agents showed weaker performance and did not benefit from visual attention directed toward the adjacent building. Active agents and incongruent agent-environment pairings further enhanced pointing accuracy, revealing that violations of expectations by agents can significantly shape navigational knowledge acquisition. Overall, agents influenced spatial exploration by directing attention locally, with the interaction between agent salience and environmental features playing a key role in shaping navigational knowledge acquisition.

neuroscience↗

bioRxiv2024

Investigating saccade-onset locked EEG signatures of face perception during free-viewing in a naturalistic virtual environment

Current research strives to investigate cognitive processes under natural conditions. Virtual reality and EEG are promising techniques combining naturalistic settings with close experimental control. However, many questions and technical challenges remain, e.g., are fixation or saccade onsets a suitable replacement as key events in continuous gaze trajectories (Amme et al., 2024), and can VR effectively capture differences across experimental conditions (Rossion & Jacques, 2008)? To address both questions, we investigate the N170 face effect in a free-viewing immersive VR study that contained houses, various background stimuli, and, notably, static and moving pedestrians to study face perception under naturalistic conditions. Our results show that aligning trials to saccade-onset leads to more well-defined ERPs, especially for the P100 component, and support that saccade-onset ERPs are the better-suited analysis method than fixation-onset ERPs for this type of experiment. Further, we observe an evolution of condition-based differences, i.e., face vs. background fixations, compatible with previous reports but extending in a large temporal window and including all electrode sites at different points in time. In summary, experiments combining VR, EEG, and eye-tracking provide further insights into the processing of faces and the relevance of saccadic onsets as event triggers under natural conditions. Significance StatementWith the effort of investigating and understanding cognitive processes under naturalistic conditions, combining virtual reality and EEG can be fruitful to implement free-viewing studies. The current work combines these technologies to explore key challenges in the context of face perception in an immersive virtual environment. Our results show that saccade-onset ERPs yield more precise measurements when analyzing continuous eye-tracking data than fixation onsets. Furthermore, when processing face compared to background stimuli, distinct temporal patterns encompassing all electrode sites can be observed, offering new insights into face perception. Overall, this work highlights the potential of integrating VR and EEG to advance our understanding of cognitive processes in naturalistic settings.

neuroscience↗

bioRxiv2024

The role of IAA and its transport in the complex streptophyte algae Chara braunii

The role of auxin indole-3-acetic acid (IAA), a phytohormone with numerous morphogenic functions, is now well-established in land plants. Although the role of IAA and its transport in algae remains unclear, PIN-driven auxin export is probably an ancient and conserved trait within Streptophytes. Among streptophyte algae, Chara represents a genus with a considerable degree of complexity in body arrangement. This study investigates the auxin response and characterizes homologs of land plant PIN auxin efflux carriers in Chara braunii. Through regeneration experiments, we observed that IAA significantly promotes elongation of thallus and side branch development upon thallus tip decapitation, indicating an effect on morphogenesis. We show that IAA is actively uptaken and metabolized by thallus cells and that this process is influenced by N-1-naphthylphthalamic acid (NPA). To elucidate the underlying mechanisms, we cloned and sequenced the most expressed Chara braunii PINs, CbPINa and CbPINc. Using epitope-specific antibodies, we showed their presence in the plasma membrane (PM) of vegetative internodal cells and generative antheridial cells. Functional tests in tobacco BY-2 cells, supported by in silico docking of IAA and NPA to CbPINa and CbPINc, showed that PM-localized CbPINa interferes with auxin transport in contrast to ER-localized CbPINc. Finally, our phosphoproteome analysis indicated that IAA rapidly induces specific phosphorylation events, including RAF-like kinase phosphorylation, highlighting a potential role for IAA in fast signaling processes in Chara braunii. Altogether, we provide new insights into IAA role in Chara braunii morphogenesis and suggest that while the canonical auxin transport mechanism may not be conserved, auxin still may likely play a role in rapid signaling pathways in this close relative of land plants.

plant biology↗

bioRxiv2024

Circulation of West Nile Virus and Usutu Virus in Birds in Germany, 2021 and 2022.

BackgroundUsutu virus (USUV) and West Nile virus (WNV) are zoonotic arthropod-borne orthoflaviviruses. The enzootic transmission cycles of both include Culex mosquitoes as vectors and birds as amplifying hosts. For more than ten years, these viruses have been monitored in birds in Germany by a multidisciplinary network. While USUV is present nationwide, WNV used to be restricted to the central-east. MethodsIn 2021 and 2022, over 2300 live bird blood samples and organs from over 3000 deceased birds were subjected to molecular and serological analysis regarding presence of WNV and USUV. The samples were collected at sites all over Germany. ResultsCirculation of both viruses increased in 2022. For USUV, the nationwide presence of lineages Africa 3 and Europe 3 reported in previous years was confirmed. Lineage Europe 2, formerly restricted to the German east, was able to expand westward. Nonetheless, USUV neutralizing antibody (nAb) detection rates remained low (< 9%). 2021 and 2022 were characterized by stable enzootic circulation of WNV lineage 2, dominated by one previously identified subcluster (95% of generated sequences). In 2022, more than 20% of birds in the endemic region in eastern Germany carried nAb against WNV. Serological data also indicate expanding WNV circulation west and south of the known hotspots in Germany. ConclusionsUSUV circulates enzootically nationwide. Emergence of WNV at several new locations in Germany with a potential increase in human infections may be imminent. In this context, wild bird monitoring serves as a capable early-warning system in a One Health setting.

microbiology↗

bioRxiv2024

The Three Stages of Learning to Master a Sensory Augmentation Device: Activation - Acquisition - Integration

By augmenting sensory perception through technology, researchers study how humans use and perceive the novel sensory input provided. Nevertheless, little is known about how learning unfolds over time. To this end, 27 participants trained with an augmentation device (feelSpace belt), which provides tactile feedback about the direction of the cardinal north, over the course of six weeks. During the training phase, we tracked participants progress using two different self-report questionnaires containing Likert-scale and open questions. Experts quantified responses to open questions using a previously established category system. As human raters are known to be susceptible to biases, we later reproduced the expert categorization using ChatGPT-4, finding a high congruence between the two classification approaches. The results suggest a three-stage model that best describes the process of acquiring an augmented sense. During the early activation stage, processing the augmented signal requires effort, induces fatigue, and a heightened awareness of the environment. In the knowledge acquisition phase, participants develop a more detailed cognitive spatial representation containing information about objects and places in relation to their current location. The deep integration stage is marked by participants seamlessly integrating the augmented information into existing perceptual processes and automatic use. The results support the supervised use of large language models (LLMs) for the analysis of qualitative data.

neuroscience↗

bioRxiv2024

Origin and evolution of Auxin Efflux Carrier family: PIN, PILS, GPR155 and the others

The resolution of the 3D structure of PIN proteins and the ability to universally predict protein structures using AlphaFold allowed us to reconsider the classification of Auxin efflux carriers within the BART superfamily, and we propose to merge members of this superfamily, possessing a characteristic fold with a helical crossover, with other families carrying this fold (BASS, NhaA, CPA and others) into a newly proposed superfamily named X-Helices Carriers (XHC). We further demonstrate a profound divergence between PIN and PILS proteins and monophyly of eukaryotic PINs with the animal cholesterol receptor GPR155/LYCHOS. We hypothesise that its signalling capacity is derived from a general feature of PIN proteins to interact with membrane lipids within the core membrane fold. Finally, we discuss the auxin-transport ability of PIN and PILS proteins in the context of the described properties of bacterial homologs that act as organic acid permeases. DisclaimerThis version is a draft and it will be updated during the next few weeks. HighlightsO_LIPINs are in plants and fragmentary in many algae and protists, but never in fungi C_LIO_LIEukaryotic PINs are monophyletic together with animal cholesterol receptor GPR155 C_LIO_LIPILS are frequently present in protists and in all fungi, but not in animals C_LIO_LIPINs/PILS split is occurred very early in Prokaryota C_LIO_LIAECs belongs to proposed superfamily of transporter with helical crossover C_LI

evolutionary biology↗

bioRxiv2023

Sorting receptor SORCS2 facilitates a protective stress response in pancreatic islets

ObjectiveSORCS2 is an intracellular sorting receptor genetically associated with body mass index (BMI) in humans, yet its mode of action remains unknown. Elucidating the receptor function that defines its role in metabolic health is the objective of this work. MethodsCombining in vivo metabolic studies in SORCS2-deficient mouse models with ex vivo structural and functional analyses as well as single-cell transcriptomics of murine pancreatic tissues, we studied the pathophysiological consequences of receptor dysfunction for metabolism. ResultsOur studies identified an important role for SORCS2 in islet stress response essential to sustain glucose-stimulated insulin release. In detail, we show that SORCS2 is predominantly expressed in islet alpha cells. Loss of receptor expression coincides with the inability of these cells to produce osteopontin, a secreted factor that facilitates insulin release from beta cells under stress. In line with diminished osteopontin levels, beta cells in SORCS2- deficient islets show changes in gene expression patterns related to aggravated ER stress, protein misfolding, as well as mitochondrial dysfunction; and they exhibit defects in insulin granule maturation and a blunted response to glucose stimulation in vivo and ex vivo. Impaired glucose tolerance in receptor mutant mice coincides with alterations in body weight and composition. ConclusionOur data identified a novel concept in protective islet stress response involving the alpha cell receptor SORCS2 and provide experimental support for association of SORCS2 with metabolic control in humans.

molecular biology↗

bioRxiv2023

SorLA restricts TNFalpha release from microglia to shape glioma-supportive brain microenvironment

SorLA, encoded by the gene SORL1, is an intracellular sorting receptor of the VPS10P domain receptor gene family. Although SorLA is best recognized for its ability to shuttle target proteins between intracellular compartments in neurons, recent data suggest that also its microglial expression can be of high relevance for the pathogenesis of brain diseases, including glioblastoma (GBM). Here we interrogated the impact of SorLA on the functional properties of glioma-associated microglia and macrophages (GAMs). In the GBM microenvironment, GAMs are re-programmed and in turn lose the ability to elicit anti-tumor responses. Instead, they acquire glioma-supporting phenotype, which is a key mechanism promoting glioma progression. Our analysis of scRNA-seq data from GBM patients revealed that the pro-tumorigenic and pro-inflammatory properties of GAMs are linked to high and low SORL1 expression, respectively. Using cell models, we confirm that SorLA levels are differentially regulated by the presence of glioma cells and by inflammatory cues. We further show that SorLA acts as a sorting receptor for the pro-inflammatory cytokine TNF to restrain its secretion from microglia. As a consequence, loss of SorLA enhanced the pro-inflammatory potential of microglia, having a remarkable impact on glioma progression. In a murine model of glioma, SorLA-deficient mice develop smaller tumors and show hallmarks of anti-tumor response including altered microglia morphology, enhanced necroptosis, and massive neutrophil influx into the tumor parenchyma. Our findings indicate that SorLA is a key player in shaping the phenotype of GAMs, and its depletion can unlock an anti-tumor response. Significance statementOur study provides insight into the mechanisms shaping the tumor microenvironment in glioblastoma (GBM), the most prevalent and aggressive brain malignancy in adults. Poor prognosis in GBM largely results from the properties of the glioma milieu that blocks the anti-tumor response. We show that SorLA restricts release of the pro-inflammatory cytokine TNF from microglia, thereby hampering their anti-glioma response. SorLA depletion reinforces the pro-inflammatory properties of tumor microenvironment and inhibits glioma growth. These findings have significant implications for our understanding of glioma biology, indicating SorLA-TNF interaction as a potential target in GBM therapies. They also offer a new perspective on SorLA activities in microglia which emerge as highly relevant not only for the pathogenesis GBM, but also of other brain diseases such as Alzheimers disease.

neuroscience↗

bioRxiv2023

Phytohormone profiling in an evolutionary framework

Multiple phytohormones act as conserved developmental regulators in land plants. Although the closely related streptophyte green algae typically lack full complements of molecular pathways underlying these responses, scattered reports of endogenous phytohormone production in these organisms exist. In this study, we performed a detailed LC/MS-based analysis of several phytohormones, their precursors and metabolites in all lineages of streptophyte algae. We also included chlorophyte algae and early-diverging land plants as outgroups. Free auxin, tRNA-derived cytokinins and certain phenolics including salicylic acid were found ubiquitously. However, land plants differed from green algae by the consistent detection of abscisic acid and the presence of auxin and cytokinin conjugates and trans-zeatin, supporting the hypotheses that these three phytohormones likely came to regulate development in the ancestral land plant. By contrast, we observed a patchy distribution of jasmonates among streptophytes. We additionaly analyzed the corresponding culture and empty media to account for phytohormone excretion and environmental contamination. Extracellular auxins and cytokinins were frequently detected, while agar constituted a major external source of phenolic compounds. We provide a highly comprehensive evolution-directed screen of phytohormone compound occurrence and thoroughly discuss our data in the context of current plant hormonomics and phylogenomics. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=143 SRC="FIGDIR/small/534998v1_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@1532f4org.highwire.dtl.DTLVardef@1c4396borg.highwire.dtl.DTLVardef@195d0eborg.highwire.dtl.DTLVardef@c71b11_HPS_FORMAT_FIGEXP M_FIG C_FIG

plant biology↗

bioRxiv2023

Improved spatial knowledge acquisition through sensory augmentation

Sensory augmentation offers a novel opportunity to broaden our knowledge of human perception through the use of external sensors that record information that humans cannot perceive naturally. This information is then translated in a meaningful way to be presented through an inherent sensory modality. To assess whether such augmented senses affect the acquisition of spatial knowledge during navigation, we trained a group of 26 participants for six weeks with an augmented sense for cardinal directions, called the feelSpace belt. In order to assess perceptual and behavioral changes, we compared the use of spatial strategies and the spatial navigation performance of the belt group to the performance of a control group that did not receive the augmented sense or the training. To this end, all participants explored the virtual reality environment Westbrook for 150 minutes in total. Then, the participants spatial knowledge of the virtual reality city was assessed subjectively with the FRS questionnaire and behaviorally in four immersive virtual reality tasks within Westbrook. The belt group reported a significant increase in the use of spatial strategies after training, while the groups ratings were comparable at baseline. The finding is consistent with previous studies showing cognitive and subjective changes to space perception as a consequence of wearing the feelSpace belt for an extended time period. Behaviorally, we found that the belt group acquired significantly more accurate knowledge of cardinal directions and of survey knowledge, measured in pointing accuracy, distance and rotation estimates. Finally, we found that the augmented sense also positively affects route knowledge but to a lesser degree. These results suggest that six weeks of training with the feelSpace belt lead to an improved acquisition of survey and route knowledge as reflected by an increased accuracy in survey and route knowledge tasks in a virtual city.

neuroscience↗

bioRxiv2021

Energetics but not development is impacted in coral embryos exposed to ocean acidification

In light of the chronic stress and mass mortality reef-building corals face under climate change, it is critical to understand the processes essential to reef persistence and replenishment, including coral reproduction and development. Here we quantify gene expression and size sensitivity to ocean acidification across a set of developmental stages in the rice coral, Montipora capitata. Embryos and swimming larvae were exposed to pH treatments 7.8 (Ambient), 7.6 (Low) and 7.3 (Xlow) from fertilization to 9 days post-fertilization. Embryo and larval volume, and stage-specific gene expression were compared between treatments to determine the effects of acidified seawater on early development. While there was no measurable size differentiation between fertilized eggs and prawn chips exposed to pH 7.8, 7.6, and 7.3, early gastrula and planula raised in reduced pH treatments were significantly smaller than those raised in ambient seawater, suggesting an energetic cost to developing under low pH. However, no differentially expressed genes emerged until 9 days post-fertilization. Notably, gene expression patterns of larvae developing at pH 7.8 and pH 7.3 were more similar than those developing at pH 7.6. Larvae from pH 7.6 showed upregulation of genes involved in cell division, regulation of transcription, lipid metabolism, and oxidative stress in comparison to the other two treatments. While low pH appears to increase energetic demands and trigger oxidative stress, the developmental process is robust to this at a molecular level, with swimming larval stage reached in all pH treatments. Summary statementThis developmental time series tracks the physiological and transcriptomic outcomes of early coral development under ambient pH (pH 7.8), and two low pH conditions (pH 7.6 and 7.3).

physiology↗

bioRxiv2021

Developmental series of gene expression clarifies maternal mRNA provisioning and maternal-to-zygotic transition in the reef-building coral Montipora capitata

BackgroundMaternal mRNA provisioning of oocytes regulates early embryogenesis. Maternal transcripts are degraded as zygotic genome activation (ZGA) intensifies, a phenomenon known as the maternal-to-zygotic transition (MZT). Here, we examine gene expression over nine developmental stages in the Pacific rice coral, Montipora capitata, from eggs and embryos at 1, 4, 9, 14, 22, and 36 hours-post-fertilization (hpf), as well as swimming larvae (9d), and adult colonies. ResultsWeighted Gene Coexpression Network Analysis revealed four expression peaks, identifying the maternal complement, two waves of the MZT, and adult expression. Gene ontology enrichment revealed maternal mRNAs are dominated by cell division, methylation, biosynthesis, metabolism, and protein/RNA processing and transport functions. The first MZT wave occurs from [~]4-14 hpf and is enriched in terms related to biosynthesis, methylation, cell division, and transcription. In contrast, functional enrichment in the second MZT wave, or ZGA, from 22 hpf-9dpf, includes ion/peptide transport and cell signaling. Finally, adult expression is enriched for functions related to signaling, metabolism, and ion/peptide transport. Our proposed MZT timing is further supported by expression of enzymes involved in zygotic transcriptional repression (Kaiso) and activation (Sox2), which peak at 14 hpf and 22 hpf, respectively. Further, DNA methylation writing (DNMT3a) and removing enzymes (TET1) peak and remain stable past [~]4 hpf, indicating that methylome programming occurs before 4 hpf. ConclusionsOur high-resolution insight into the coral maternal mRNA and MZT provides essential information regarding setting the stage for, and the sensitivity of, developmental success and parental carryover effects under increasing environmental stress.

developmental biology↗

bioRxiv2020

Pore constrictions in intervessel pit membranes reduce the risk of embolism spreading in angiosperm xylem

O_LIEmbolism spreading in angiosperm xylem occurs via mesoporous pit membranes between vessels. Here, we investigate how the size of pore constrictions in pit membranes is related to pit membrane thickness and embolism resistance. C_LIO_LIIn three models, pit membranes are modelled as multiple layers to investigate how pit membrane thickness and the number of intervessel pits per vessel determine pore constriction sizes, the probability of encountering large pores, and air-seeding. These estimations were complemented by measurements of pit membrane thickness, embolism resistance, and number of intervessel pits per vessel (n = 31, 31, and 20 species, respectively). C_LIO_LIConstriction sizes in pores decreased with increasing pit membrane thickness, which agreed with the measured relationship between pit membrane thickness and embolism resistance. The number of pits per vessel affected constriction size and embolism resistance much less than pit membrane thickness. A strong relationship between estimated air-seeding pressures and measured embolism resistance was observed. C_LIO_LIPore constrictions provide a mechanistic explanation why pit membrane thickness determines embolism resistance, and suggest that hydraulic safety can be uncoupled from hydraulic efficiency. Although embolism spreading remains puzzling and encompasses more than pore constriction sizes, angiosperms are unlikely to have leaky pit membranes, which enables tensile transport of water. C_LI

plant biology↗