Biology subjects

Martin, A.

Publications and source records attributed to Martin, A..

At least 37 records · Page 2Linked to original sources

bioRxiv2026

ABCG transporter knockouts alter integument and eye pigmentation with gene-specific effects on viability in butterflies and moths

Insects possess remarkable diversity in pigmentation across life stages, generated from a limited number of pigment precursors. ABCG transporters play central roles in pigmentation by mediating the intracellular transport of these precursors, yet their functions outside a few model systems remain poorly characterized. Here, we investigate the roles of the ABCG transporter genes white (w), scarlet (st), and oily kinshiryu (ok) across five lepidopteran species representing both butterflies and moths. CRISPR-Cas9 knockouts reveal conserved, tissue-specific functions of ABCG transporters throughout development, affecting larval and pupal integuments as well as adult eyes, but not scale coloration. Notably, our data indicate that both ommochrome and uric acid deposition underlie the coloration and opacity of Lepidoptera larvae and pupae, with the relative contributions of these pathways differing across species and stages. We also reveal that the vivid orange coloration of Gulf fritillary caterpillars arises from the interplay of ommochromes and urate granules, providing a clear example of how these pathways combine to produce diverse integument pigmentation. Loss of white was deleterious in four species examined, whereas scarlet knockouts produced viable individuals with easily detectable pigmentation phenotypes, identifying scarlet mutant backgrounds as a practical genetic marker for functional studies. Together, these findings show that conserved ABCG transporter complexes are differentially deployed across tissues and life stages, providing a mechanistic basis for the evolutionary diversification of pigmentation in Lepidoptera and enabling expanded functional genomics and transgenesis in emerging model species. Research HighlightsCRISPR-Cas9 disruption of ABCG transporters across Lepidoptera reveals conserved, tissue-specific roles in pigmentation. Interactions between ommochrome and uric acid deposition generate stage-specific coloration in larval and pupal integument.

genetics↗

bioRxiv2026

The ivory:mir-193 non-coding RNA gene controls melanic camouflage in a polymorphic moth

A majority of moths use melanic pigmentation to blend into the visual environment, and some species display genetically controlled color polymorphisms that provide tractable systems for dissecting the genetic basis of camouflage. Here we leveraged the natural polymorphism of Anticarsia gemmatalis moths to map a major-effect gene that controls melanic variation, and study its developmental roles using expression and loss-of-function assays. A genome-wide association mapping identifies the ivory:mir-193 non-coding RNA locus as a major locus of melanic variation, with highly-divergent haplotypes differentiating the Light and Dark morphs. Second, the expression of ivory:mir-193 prefigures the melanic coloration of each morph, and suggests that cis-regulatory variation at this locus determines the difference in adult pattern. Finally, CRISPR disruption of the ivory promoter and mir-193 hairpin region each abolish melanic scale pigmentation, demonstrating that this lnc-pri-miRNA module is required for dark-scale differentiation. These findings corroborate the emerging role of ivory:mir-193 as a key factor in the development of melanic patterning, and highlight its unique propensity to repeatedly drive phenotypic variation of adaptive potential in butterflies and moths. HighlightsO_LIAnticarsia gemmatalis display striking variation in camouflage patterns C_LIO_LIDark vs. Light color polymorphism map to the ivory:mir-193 hotspot locus C_LIO_LIHighly-diverged haplotypes drive morph-specific expression of ivory:mir-193 C_LIO_LIThe miR-193 miRNA is required for melanic scale development C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/707733v2_ufig1.gif" ALT="Figure 1"> View larger version (80K): org.highwire.dtl.DTLVardef@8e491eorg.highwire.dtl.DTLVardef@1628425org.highwire.dtl.DTLVardef@d1b691org.highwire.dtl.DTLVardef@29247b_HPS_FORMAT_FIGEXP M_FIG C_FIG

evolutionary biology↗

bioRxiv2026

Potential virulence factors in Pyrenophora teres through label-free cellular proteomics analysis

Pyrenophora teres f. teres (Ptt) is the causative agent of net blotch diseases in barley and an economically important pathogen in the barley industry worldwide. To date, however, little is known about the protein expression profile of Ptt, which is important to understand the pathogen behaviour. In this study we report the first cellular proteomics analysis of Ptt. Label-free proteomics was used to quantify the protein expression levels of two parental and one of its progeny isolates from a Ptt cross, grown in culture. One parental isolate of the cross was virulent on the barley variety Prior while the other isolate was avirulent. The progeny isolate used in this study was also virulent on Prior. A total of 3,502 proteins were identified in samples of the three Ptt isolates, of which 99 were found only in the pathogenic isolates, while another 255 proteins were significantly more abundant in the pathogenic isolates compared to the non-pathogenic isolate. Gene ontology analyses of the significant proteins revealed that the proteins increased in pathogenic isolates were involved in fatty acid elongation, biosynthesis of unsaturated fatty acids, glycerophospholipid metabolism, nucleocytoplasmic transport, amino sugar and nucleotide sugar metabolism and metabolic pathways. These protein profiles and the bioinformatic analysis provide new biological information that can be utilised to better understand the pathogenicity of Ptt.

plant biology↗

bioRxiv2026

Telomere length of both parents contribute to heritable POT1 cancer-predisposition syndrome

Germline mutations in POT1 are linked to familial cancer predisposition, and somatic POT1 mutations occur recurrently in tumors. These mutations promote oncogenesis by enabling aberrant telomere elongation. For inherited POT1 mutations, a critical question is the extent to which elongated telomeres are transmitted to the next generation from the POT1 carrier parent and whether the inherited excessively long telomeres elevate cancer risk. Using a nanopore sequencing approach that provides haplotype-specific telomere length measurements, we examined telomere inheritance in families harboring POT1 mutations. We found that individuals preferentially inherit their longest telomeres from the carrier parent, consistent with extensive telomere elongation in the carrier germline, whereas comparatively short telomeres are predominantly inherited from the non-carrier parent. Analysis of carrier and non-carrier siblings further showed that telomeres inherited from both parents are elongated in POT1 carriers, with the shortest telomeres undergoing preferential elongation. These findings support a potential mechanism of genetic anticipation in which POT1 mutations progressively reduce the likelihood that short telomeres capable of enforcing telomere-based tumor suppression are inherited from the carrier parent. Together, our results demonstrate that telomeres inherited from both parents jointly shape telomere-based tumor suppressive barriers. Summary sentenceAllele specific nanopore sequencing reveals that POT1 mutations reshape germline and somatic telomere dynamics, uncovering a novel mechanism of generational anticipation driven by preferential elongation of short inherited telomeres.

genetics↗

bioRxiv2026

QTL mapping and proteomic profiling of barley: insights into resistance and susceptibility to Pyrenophora teres f. teres

Pyrenophora teres f. teres (Ptt), the causal agent of net form net blotch disease in barley, is an economically important fungal pathogen worldwide. Understanding both host resistance mechanisms and pathogen virulence factors is essential for developing durable net form net blotch resistant barley cultivars. Quantitative trait loci (QTL) mapping was conducted using a cross between two Ptt isolates, one virulent on the barley cultivar Prior and the other being avirulent. A major QTL associated with virulence on Prior was detected on chromosome 5. A progeny isolate possessing this QTL, together with the two parental isolates, was subsequently used in the proteomic analyses. Label-free proteomics was used to quantify in planta the protein profile changes in Prior following inoculations with the virulent and avirulent parental Ptt isolates, and the virulent progeny isolate. Leaf samples were collected at two (D2) and five (D5) days post-inoculation, and proteomic analyses performed to identify proteins associated with host resistance and pathogen virulence. A dataset comprising 2,886 barley proteins and 51 Ptt proteins was analysed. Principal component analysis (PCA) of the barley Prior proteomes revealed distinct clustering based on resistance and susceptibility at D5, while D2 samples formed a separate cluster. The PCA of the Ptt proteomes identified separate clusters, one comprised of the D2 and D5 avirulent parental isolate and another cluster of the virulent isolates at D5 only. Gene ontology analysis of the Prior proteins that were significantly increased in the resistant compared to the susceptible groups revealed functional categories related to protein translation, biosynthesis and chloroplast activities. The proteins that were significantly increased in the susceptible compared to the resistant Prior group were associated with organic acid and carbohydrate metabolism. The proteomic profiles and bioinformatic analysis generated in our study provide novel insights into the molecular basis of resistance and virulence in the barley-P. teres pathosystem. Key messageThis study reveals the first in planta proteomic profiles of both barley and Pyrenophora teres f. teres, identifying unique virulence-associated proteins and host responses linked to resistance and susceptibility.

plant biology↗

bioRxiv2026

Integrative genomic approaches to study the barley-Pyrenophora teres interaction

Pyrenophora teres f. teres (Ptt), the causal agent of net-form net blotch in barley, was studied using a bi-parental mapping population (Pop1) of 305 isolates derived from a cross between two isolates with contrasting virulence on barley cultivars Skiff and Prior. QTL analysis identified virulence loci on chromosomes (Chr) 3 and 10 for Skiff, and on Chr 1, 4, and 5 for Prior. Major QTL on Chr 3 and 5 explained 24% and 40% of phenotypic variation, respectively. A second population (Pop2) was developed by crossing two Pop1 isolates, one carrying major QTL on Chr 3 and 5 and one avirulent. Isolates from Pop2 with single QTL were phenotyped across a Prior/Skiff recombinant inbred line population to identify corresponding host susceptibility/resistance loci. Skiff virulence QTL on Chr 3 corresponded to barley Chr 3H and 6H, while Prior virulence QTL on Chr 5 mapped to Chr 6H. RNA expression analysis of virulent and avirulent Pop2 isolates identified five candidate genes linked to the Chr 5 QTL, including two predicted effectors. These findings suggest both gene-for-gene and inverse gene-for-gene interactions in the Ptt-barley pathosystem and advance the understanding of molecular mechanisms underlying host-pathogen specificity.

plant biology↗

bioRxiv2026

A searchable metadata network graph for microbiome metabolomics

Establishing the biological context of microbial metabolites remains a major challenge. We present microbiomeMASST, a metadata-driven network graph that maps metabolites across 467 available datasets with 144,424 mass spectrometry files from humans, animals, and microbial culture systems. MicrobiomeMASST integrates monocultures, synthetic communities, and host-associated samples across multiple body sites and plants. MS/MS spectra can be queried to trace occurrence across hosts, experimental conditions, and interventions, enabling cross-study integration. We demonstrate this framework by contextualizing microbial-conjugated bile acids and interrogating microbiome-mediated drug metabolism. Screening gut bacteria revealed deprolylation of the angiotensin-converting enzyme (ACE) inhibitor prodrug enalapril. Using microbiomeMASST, we traced this metabolite across human cohorts, microbial isolates, environmental samples, and in Gorilla gorilla. Structural modeling and enzymatic assays showed that microbial deprolylation abolishes ACE inhibition, thereby inactivating its therapeutic effect. Together, microbiomeMASST links MS/MS spectra to biological context, converting isolated observations into an interpretable microbiome map for cross-study analysis.

biochemistry↗

bioRxiv2026

Common and distinct contributions of the dorsomedial prefrontal and posterior parietal cortices to social episodic memory

The self-reference effect (SRE) refers to the robust mnemonic advantage for self-relevant information and is characterised by a graded pattern spanning the self, close others, and distant others. Despite extensive behavioural evidence, causal evidence for the neural mechanisms supporting the SRE remains limited, particularly during incidental encoding and across source memory, metacognition, and emotional valence. We investigated the causal contributions of the dorsomedial prefrontal cortex (dmPFC) and posterior parietal cortex (PPC) to self-other episodic memory and metacognition using focal transcranial direct current stimulation (tDCS). One hundred participants completed an incidental encoding task in which trait adjectives were rated with reference to the self, a close friend, or a celebrity, under anodal or sham stimulation to either region. Recognition tests assessed item and source memory sensitivity (d') and metacognitive efficiency (meta-d'/d') as a function of agent and emotional valence. Across stimulation conditions, a graded advantage for self-related information was observed in both item and source memory, extending to metacognitive efficiency. Anodal stimulation to either region attenuated the self-reference effect. PPC stimulation additionally biased source memory away from positive and towards negative information. These findings demonstrate shared and dissociable causal roles of dmPFC and PPC in self-other episodic memory.

neuroscience↗

bioRxiv2025

Identification of novel ubiquitin receptors on the 26S proteasome by photo-crosslinking mass spectrometry

The 26S proteasome is the endpoint of the ubiquitin-proteasome system, an essential pathway for maintaining cellular homeostasis through targeted degradation of misfolded, damaged, and obsolete proteins. Substrates labeled with ubiquitin are directed to the 26S proteasome by binding to one or more ubiquitin receptors. However, ubiquitin-dependent degradation occurs even when the canonical receptor sites are mutated, suggesting the presence of additional, unidentified binding sites. Here we created photo-crosslinkable probes for ubiquitin interactions by incorporating the unnatural amino acid p-benzoyl-L-phenylalanine into ubiquitin. We show that these probes can be used to measure apparent affinities for known receptors and to reveal novel ubiquitin-binding sites on the yeast 26S proteasome. Through photo-crosslinking mass-spectrometry experiments we identified a groove on the top of the proteasome, formed by Rpn2, Rpn9, Rpn10, and Rpn12, that serves as an additional ubiquitin-binding interface. Our photo-crosslinkable probes thus serve as versatile tools for the characterization of ubiquitin-protein interactions and the identification of ubiquitin-binding domains.

biochemistry↗

bioRxiv2025

Proteasome activator Blm10 maintains cellular proteostatic balance and gamete quality in budding yeast

The proteasome is responsible for regulated protein degradation in eukaryotic cells. Its best characterized substrates are ubiquitinated proteins that are targeted to the 26S proteasome complex, consisting of a 19S regulatory particle (RP) capping the barrel-shaped 20S core peptidase (CP). The CP can interact with other caps, including Blm10/PA200, a nearly 250 kDa protein whose biological function is not well understood. Blm10 is upregulated during gametogenesis in budding yeast, suggestive of a natural stage-specific modulation of proteasome composition. Here, we investigate the function of Blm10 during yeast gametogenesis, identifying it as a weak activator of the proteasome that can displace the 19S RP from the CP. Due to this competition for the CP, overexpression of Blm10 can lead to attenuation of ubiquitin-dependent degradation and proteostatic defects. Cells lacking Blm10 also display markers of proteostatic stress, including Hsp104 foci and heat sensitivity, suggesting that Blm10 safeguards normal proteostatic balance. We find that Blm10 is important for producing fit gametes and ensuring full rejuvenation of aged cells following gametogenesis. Furthermore, we observe direct association of aggregate-prone proteins and protein-folding factors with immunoprecipitated Blm10-proteasomes. Finally, we discovered that 14-3-3 proteins Bmh1/2 are novel cofactors of Blm-10 bound proteasomes and describe how Blm10 controls CP gate configuration. Overall, our data suggest a role for Blm10-proteasomes in maintaining gamete proteostasis through fine-tuning of proteasome activity and prevention of protein aggregation.

molecular biology↗

bioRxiv2025

Faf1 accelerates p97-mediated protein unfolding by promoting ubiquitin engagement

P97/VCP is a protein unfoldase of the AAA+ ATPase family that plays essential roles in numerous processes, including ER-associated degradation and DNA replication. For unfolding of proteins that are modified with K48-linked ubiquitin chains, p97 works with the heterodimeric cofactor Ufd1-Npl4, and the cofactor Faf1 was shown to enhance this activity during replisome disassembly, yet the mechanisms remain unknown. Here, we employ an in vitro reconstituted system with human components for biochemical experiments, FRET-based assays, and cryo-EM structure determination to reveal that Faf1 plays a generic role in accelerating ubiquitin-dependent substrate processing by promoting the unfolding of an initiator ubiquitin and its engagement by the ATPase. Faf1 thereby uses its p97-bound C-terminal UBX domain to anchor a long helix that braces the UT3 domain of Ufd1 and stabilizes the Ufd1-Npl4 cofactor for ubiquitin unfolding. Our findings demonstrate how p97 works simultaneously with several cofactors to facilitate the unfolding of ubiquitinated proteins, indicating more complex regulatory mechanisms for substrate selection than for the simpler yeast Cdc48.

biochemistry↗

bioRxiv2025

WntA expression and wing transcriptomics illuminate the evolution of stripe patterns in skipper butterflies

Skippers (Hesperiidae) form a distinct lineage of butterflies where the developmental mechanisms of color patterning have seldom been studied. The wing patterns of skippers often consist of median stripes, and classic comparative morphology studies suggest these elements are homologous to the Central Symmetry System (CSS) found in nymphalid butterflies. Consistent with this hypothesis, we show here that expression of the signaling ligand gene WntA, a marker of the CSS in nymphalids, prefigures the position of the main wing patterns of the silver-spotted skipper Epargyreus clarus. Notably, WntA expression is associated with different color outputs in the forewing vs. hindwing, validating a theory of pattern homology from the mid-twentieth century. To further gain insights into the genes associated with this patterning process, we generated an annotated genome for E. clarus and performed an RNAseq study profiling gene expression along the proximo-distal (P-D) axis of early pupal wings. These data suggest that the transcription factor genes lobe, u-shaped, and odd-paired are expressed in restricted P-D sections of the wing similarly to WntA, indicating they may participate in the patterning of the CSS. In addition, inverted expression patterns of dachsous and four-jointed, as well as the expression of transcription factors with roles in specifying proximal (homothorax, tiptop/teashirt) and distal (vestigial, scalloped) section of ths Drosophila wing disk, suggest a deep conservation of wing P-D patterning process between Diptera and Lepidoptera. This work highlights the developmental homology between the CSS of Hesperiidae and Nymphalidae, and enriches our knowledge of patterning mechanisms in lepidopteran wings. Summary StatementThis study reveals how skipper butterfly wing stripes share deep developmental origins with other butterflies, offering fresh insight into wing pattern evolution.

developmental biology↗

bioRxiv2025

Allogeneic Polyclonal CD38KO/CD38-CAR γδT Cells For The Treatment Of T Cell Malignancies

Relapsed and refractory T cell malignancies are associated with poor clinical outcomes. Autologous sources of {beta}T cells have been employed for chimeric antigen receptor (CAR) therapies to eliminate the potential for graft-vs-host disease (GvHD). However, the application of CAR-T therapy for T-ALL has been hindered by an inability to obtain sufficient healthy {beta}T cells from patients combined with fratricide due to concurrent antigen expression on normal T cells. Here, we genetically engineered polyclonal {gamma}{delta}T cells, which do not cause GvHD, as an allogeneic source for cancer immunotherapy targeting the pancancer antigen CD38. Utilizing a novel expansion protocol in combination with CRISPR/AAV gene editing, we developed CD38KO/CD38-CAR polyclonal {gamma}{delta}T cells that target T-ALL. Our editing strategy enabled site-directed, on-target insertion of the CD38-CAR transgene into the CD38 locus, with no evidence of significant random CAR DNA integration (as commonly seen with lentiviral CAR transduction) or chromatin abnormalities resulting from CRISPR editing. This enhanced targeting effectively mitigated fratricide through simultaneous CD38 disruption and CAR expression. We demonstrated the efficacy of the CD38KO/CD38-CAR {gamma}{delta}T cells in vitro across multiple patient-derived T-ALL samples collected at baseline and relapse. In vivo, a single injection of CD38KO/CD38-CAR {gamma}{delta}T cells without exogenous cytokine support resulted in potent anti-leukemic efficacy. Fratricide-resistant CD38KO/CD38-CAR polyclonal {gamma}{delta}T cells thus represent a promising off-the-shelf therapeutic platform for T cell malignancies and other CD38-expressing cancers. Key PointsO_LIHybrid pan-{gamma}{delta}TCR antibody/mbIL21-41BBL feeder expansion yields high-purity, polyclonal {gamma}{delta}T cells suitable for CRISPR/AAV editing. C_LIO_LIOn-target CD38-CAR knock-in with simultaneous CD38 knockout prevents fratricide and enables potent T-ALL killing in vitro and in vivo. C_LI

immunology↗

bioRxiv2025

Baseline cognition and Stimulation Site Shape the Effects of tDCS on Verbal Fluency in Older and Younger Adults

Verbal fluency is a core measure of language and executive function often used in cognitive research. Transcranial direct current stimulation (tDCS) has been investigated for its potential to enhance verbal fluency; however, the results are variable. Discrepancies may indicate variations in electrode montage, stimulation site, measured fluency type, and individual cognitive profiles. In this preregistered, double-blind, sham-controlled study, 72 younger and 72 older adults received anodal tDCS to either the left inferior frontal gyrus (left IFG) or the left temporoparietal junction (left TPJ) while completing phonemic and semantic fluency tasks. Anodal stimulation of the left TPJ significantly improved phonemic fluency compared to sham (F(1,71) = 4.49, p = .038), with no effects observed for semantic fluency or left IFG stimulation. Additionally, stimulation response in the TPJ group was predicted by fluid intelligence, with lower scores associated with greater benefit (F(1,70) = 7.80, p = .007). Finally, stimulation to the left IFG improved response initiation but impaired sustained energization over the entire minute. These results suggest that the efficacy of focal tDCS for enhancing verbal fluency depends on both stimulation site and task demands, with the left TPJ showing selective benefits for phonemic fluency. Importantly, individual differences in fluid intelligence, but not age, moderated stimulation response, highlighting the role of cognitive capacity in neuromodulation outcomes. Together, these findings demonstrate a nuanced relationship between targeted excitation of the language network and verbal fluency, emphasizing the need for individualized approaches in cognitive enhancement interventions.

neuroscience↗

bioRxiv2025

Growth Cost and Transport Efficiency Tradeoffs Define Root System Optimization Across Varying Developmental Stages and Environments in Arabidopsis

Root system architecture (RSA) is central to plant adaptation and fitness, yet the design principles and regulatory mechanisms connecting RSA to environmental adaptation are not well understood. We developed Ariadne, a semi-automated software for quantifying cost-efficiency tradeoffs of RSA by mapping root networks onto a Pareto-optimality framework, which describes the balance between resource transport efficiency and construction cost. Applying Ariadne to Arabidopsis thaliana, we found that root architectures consistently assume Pareto-optimal forms across developmental stages, genotypes, and environmental conditions. Using the Discovery Engine, an engine that combines machine learning together with interpretability techniques, we found developmental stage, the hy5/chl1-5 genotype, and manganese availability as important determinants of the cost-efficiency tradeoff, with manganese exerting a unique influence not observed for other nutrients. These results reveal that RSA plasticity is genetically constrained to cost-efficiency optimal configurations and that developmental and environmental factors shift RSA on the pareto front, with manganese acting as a strong modulator of the transport efficiency and construction cost balance.

plant biology↗

bioRxiv2025

Regionalization of gene expression and cell types in the silk gland of the pantry moth Plodia interpunctella

Lepidopteran silk glands include a posterior silk gland (PSG) that secretes core fibers and a middle silk gland (MSG) that secretes adhesive sericins. While well-studied in the silkworm (Bombyx mori), little is known about the gene expression profiles underlying the diversity of lepidopteran silks. Here we characterized the silk gland from the pantry moth Plodia interpunctella using a combination of quantitative and spatial assays. RNA-seq analyses of differential gene expression between the MSG and PSG depict the transcriptomic divergence between these two secretory tissues. In the PSG, high expression of fibroin genes FibL and FibH were detected, whereas MSG samples were dominated by transcripts encoding major sericins-- bioadhesive proteins that form the coating of the silk fiber. Hybridization Chain Reaction (HCR) mRNA profiling revealed sharp cellular boundaries within the silk gland: PSG cells exclusively expressed fibroins, while MSG comprised two compartments each expressing different combinations of sericins. Our findings corroborate the conserved organization of lepidopteran silk glands into specialized secretory subdivisions, and establish Plodia as a promising comparative model for studying silk diversity. This work provides a foundation for future research into the cellular and evolutionary basis of silk production across Lepidoptera.

genomics↗

bioRxiv2025

Repetition-related reductions in neural activity support improved behavior through increases in oscillatory power

Repeatedly processing an object leads to subsequent behavioral improvements in its identification and reductions in associated neural activity, a form of neural processing efficiency that multiple theoretical models have attempted to explain. Using simultaneous fMRI-EEG in humans during object naming, we find that stimulus-driven oscillatory power from high (gamma) to low frequencies (theta) increases and resolves earlier with repetition in task-engaged frontal and occipitotemporal brain regions identified as showing repetition suppression in fMRI. Changes in gamma oscillatory power in these regions were correlated with behavioral priming across subjects and additionally with fMRI repetition suppression in left frontal cortex, providing multimodal support for a novel mixture of the previously proposed Synchrony and Facilitation models.

neuroscience↗

bioRxiv2025

A lateral tension model for cranial mouse neural tube closure

Embryos fold their tissues into increasingly complicated shapes during development. Cells produce and coordinate the forces needed to fold tissues through networks of F-actin and Myosin II (actomyosin). We can discern the mechanical mechanisms used to fold tissues by analyzing these networks. Apical actomyosin is required to fold the neuroepithelium (NE), with a midline hinge and lateral neural folds into the neural tube. However, the large size and complex tissue curvature has complicated a detailed analysis of its actomyosin networks. Here, we developed a computational workflow to create 2D apical shell reconstructions of the NE. Using these projections, we confirmed a midline-lateral gradient of apical cell area and discovered a negative correlated gradient of actomyosin density. We hypothesized that lateral neural folds, with high apical cell constriction and actomyosin, have higher apical tension than the midline hinge, with large apical cell area and low actomyosin. Through target laser ablations in live embryos that allow us to infer tension, we confirmed that tension is isotropic and low at the midline and anisotropic and high on the lateral neural folds. Finally, we identified sex differences in cell shape, apical constriction rates, actomyosin in the NE at an earlier time point than previously appreciated. We use these findings to propose a lateral tension mechanism used in murine NTC that is distinct from the contractile hinge mechanism identified in other model systems.

developmental biology↗