Biology subjects

Bates, A.

Publications and source records attributed to Bates, A..

15 recordsLinked to original sources

bioRxiv2026

Human 3D epithelioids enable continuous long-term clonal evolution studies across multiple epithelial tissues

Modeling human epithelia in vitro remains challenging because current systems do not fully preserve the combination of architecture, heterogeneity, clonal composition, and long-term dynamics shown in vivo. While 3D approaches such as organoids and organotypic cultures capture important aspects of lineage differentiation and niche signaling, they often lose stable organization over time, limiting studies of long-lasting processes such as clonal evolution and cell competition. Here, we present human epithelioids as continuous long-term, 3D epithelial cultures efficiently derived from eight adult human epithelia, including trachea, skin, buccal mucosa, esophagus, blader, urethra, submandibular gland and endometrium. Using immunostaining, electron microscopy, single-cell RNA sequencing, functional assays and somatic mutation analyses, we deeply characterized human epithelioids and confirmed that they recapitulate native architecture and cell diversity, sustain regenerative capacity, and preserve donor-specific mutational landscapes, establishing a robust and versatile platform for longitudinal interrogation of clonal evolution, tissue dynamics and responses to clinically relevant perturbations, including radiotherapy and chemotherapy, over extended timescales.

cancer biology↗

bioRxiv2026

The genome of an enigmatic sea urchin parasite Echinomermella matsi Jones & Hagen, 1987 resolves its place among other invertebrate parasitic nematodes

We present a genome of Echinomermella matsi (Nematoda: Plectida: Benthimermithidae), a body cavity parasite of the green sea urchin Strongylocentrotus spp. commonly found along the coast of Central and Northern Norway. Three assemblies were generated, one from multiple individuals using Oxford Nanopore long read data and two from two individuals using PacBio long read data. The genome of Echinomermella matsi is 65 Mb long consisting of 7 chromosomes, with nematode Benchmarking Using Single Copy Orthologue (BUSCO) completeness reaching 61%. The E. matsi chromosome complement corresponds to the proposed Rhabditida ancestral linkage groups. Phylogenetic analyses using newly generated 18S rRNA genes and a multigene dataset consisting of BUSCO protein coding genes, supported by morphological observations of juveniles, firmly place Echinomermella within the nematode order Plectida, alongside nematode parasitoids of marine invertebrates, Trophomera or Neocamacolaimus. As a result, the generally free-living order Plectida includes at least three independently evolved lineages of nematodes symbiotic with various groups of aquatic and terrestrial invertebrates and with unicellular organisms. This, and the fact that Plectida is the closest sister lineage to Rhabditida as a whole, and one node away from the exclusively animal parasitic Spirurina, makes this lineage a valuable model for study of evolution of animal parasitism in the aquatic environment. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/699767v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@d44b08org.highwire.dtl.DTLVardef@18a3310org.highwire.dtl.DTLVardef@1e79dforg.highwire.dtl.DTLVardef@d33b3b_HPS_FORMAT_FIGEXP M_FIG C_FIG Article summaryThe researchers generated a genome of Echinomermella matsi, a body cavity parasite of the green sea urchin, using PacBio and Oxford Nanopore long read sequencing. The genome is 65 Mb long, shows 61% of nematode BUSCO completeness, and consists of 7 chromosomes. Single and multiple gene phylogenies place Echinomermella within mostly free-living Plectida as one of the three independently evolved parasitic lineages. The authors suggest Echinomermella to be a valuable model to study evolution of animal parasitism in the aquatic environment. The genome can be used to develop biocontrol strategies of Echinomermella in mariculture of green sea urchin.

genomics↗

bioRxiv2026

Roseobacter enrichment early in life facilitates future colonization of Roseobacter bacteria and improves long-term survival against Vibrio aestuarianus in the Pacific oyster

Exposure to beneficial bacteria during early immune development may promote long-term survival against pathogens, known as "microbial education." As marine diseases intensify with ocean warming, methods to improve marine organisms robustness against disease will be valuable for mitigation. Here, we experimentally tested whether exposure to high temperature seawater, seawater enrichment with Roseobacter bacteria, or a combination of both during the first 24 hours of life enhances long-term survival of the Pacific oyster (Crassostrea gigas) against the widespread marine pathogen, Vibrio aestuarianus subsp. francensis, at high temperatures (24 {degrees}C). Exposure to high temperatures early in life did not improve future survival during disease challenges and caused high larval mortality. Conversely, Roseobacter enrichment during high temperature exposure resulted in a "microbial rescue effect," improving larval survival. We found that Roseobacter enrichment during the first 24 hours of life improved future survival against V. aestuarianus at high temperatures by up to [~]28% at 13 days post-fertilization (dpf) and [~]30% at 90 dpf. Ultimately, the supplemented Roseobacter species did not remain associated with the host microbiome but instead was replaced by a high abundance of other Roseobacter bacteria at 90 dpf. These findings suggest that early Roseobacter enrichment facilitates future colonization by other Roseobacter species, which may in turn protect against pathogenic V. aestuarianus, supporting the concept of microbial education in marine invertebrates and its potential use to combat marine diseases. ImportanceThis research identifies key aspects of early developmental processes in a marine invertebrate, Crassostrea gigas, and explores how these processes can be utilized to alter host-microbe interactions later in life.

microbiology↗

bioRxiv2025

Moonlighting Role of Meiotic SYCP1 in Breast Cancer: A Chromatin-Bound Regulator of DNA Repair, Transcription, and Drug Resistance

Maintenance of genome integrity is essential for cellular homeostasis, and its perturbation leads to tumorigenesis. Here, we uncover an unanticipated somatic role for the synaptonemal complex protein SYCP1--previously regarded as strictly meiosis-specific--in a broad spectrum of human cancers including breast cancer. Through integrative genomic, proteomic, and functional analyses, we demonstrate that SYCP1 is aberrantly re-expressed in tumor cells, where it actively promotes DNA damage repair, cell cycle progression, and malignant growth. SYCP1 binds chromatin at regulatory elements and directly controls transcriptional programs governing genome maintenance, including key effectors such as CCNB1, PCNA, RAD51C, and H2AX. Loss of SYCP1 impairs DNA repair kinetics, attenuates tumor cell proliferation and migration, and increases sensitivity to chemotherapeutics cisplatin and gemcitabine. Mechanistically, SYCP1 interfaces with chromatin remodeling complexes and transcription factors SP1 and SP2, modulating their genomic occupancy and facilitating oncogenic transcriptional outputs. Clinically, high SYCP1 expression stratifies patients with poor prognosis and therapy resistance across multiple cancer types. Our findings illuminate a previously unrecognized moonlighting function of SYCP1 in somatic cancer cells and position it as a critical chromatin-associated regulator of genome stability, with implications for biomarker development and therapeutic targeting.

cancer biology↗

bioRxiv2025

LAMPrey: a standardised method for analysing quantitative LAMP (qLAMP) and qPCR reactions using the inflection cycle threshold iCt

Quantitative Loop-mediated isothermal amplification (qLAMP) is a relatively new method that has gained popularity in recent years, particularly in disease identification, including during the recent SARS-CoV-2 pandemic. Unlike conventional quantitative PCR (qPCR), qLAMP features a linear amplification phase before the exponential phase. Determining cycle threshold (Ct) values through automatic thresholding may therefore produce inaccurate results, and the nature of these thresholds complicates comparability between studies and softwares. We introduce a new method for transforming sigmoidal amplification curves into inflection threshold curve (iCt) to address issues with auto thresholds and analysis of qLAMP. This method is implemented as a collection of R functions named LAMPrey, suitable for analysis of both qPCR and qLAMP reactions performed in the two most commonly used real-time thermocyclers. We simulate qLAMP amplification differences, demonstrate that iCt and Ct methods perform equivalently for conventional qPCR with an Illumina library quantitation kit, and show that iCt values outperform Ct values for quantifying qLAMP reactions in zebrafish embryos. All scripts developed for this paper are available at https://github.com/dodged13/LAMPrey Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=96 SRC="FIGDIR/small/651076v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@d5bbforg.highwire.dtl.DTLVardef@102713eorg.highwire.dtl.DTLVardef@158bcbcorg.highwire.dtl.DTLVardef@cf11b3_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2025

On the path to reference genomes for all biodiversity: lessons learned and laboratory protocols created in the Sanger Tree of Life core laboratory over the first 2000 species

Since its inception in 2019, the Tree of Life programme at the Wellcome Sanger Institute has released high-quality, chromosomally-resolved reference genome assemblies for over 2000 species. Tree of Life has at its core multiple teams, each of which are responsible for key components of the genome engine. One of these teams is the Tree of Life core laboratory, which is responsible for processing tissues across a wide range of species into high quality, high molecular weight DNA and intact RNA, and preparing tissues for Hi-C. Here, we detail the different workflows we have developed to successfully process a wide variety of species, covering plants, fungi, chordates, protists, arthropods, meiofauna and other metazoa. We summarise our success rates and describe how to best apply and combine the suite of current protocols, which are all publicly available at protocols.io.

molecular biology↗

bioRxiv2024

The molecular arsenal of the key coastal bioturbator Hediste diversicolor faced with changing oceans

The importance of infaunal bioturbators for the functioning of marine ecosystems cannot be overstated. Inhabitants of estuarine and coastal habitats are expected to show resilience to fluctuations in seawater temperature and pH, which adds complexity to our understanding of the effects of global change drivers. Further, stress responses may be propagated through chemical cues within and across species, which may amplify the costs of life and alter species interactions. Research into the molecular mechanisms underlying this resilience has been limited by a lack of annotated genomes and associated molecular tools. In this study, we present the first chromosome-level, annotated draft genome of the marine ragworm Hediste diversicolor, specifically mapping genes important for chemical communication, sensing and pH homeostasis. Using these resources, we then evaluate the transcriptomic and behavioural responses of two distinct populations -- one field-sampled from Portugal (Ria Formosa) and one laboratory-acclimated and -bred from the United Kingdom (Humber) -- to changes in seawater pH, temperature, and odour cues from a low pH-stressed predator. Both populations displayed adaptive responses to future oceanic conditions, with targeted acid-base regulation in the Ria Formosa population experiment, and broader changes in metabolism and growth genes in the Humber population experiment. Chemical cues from stressed fish predators induced genes related to Schreckstoff biosynthesis in ragworms. Additionally, under future ocean conditions including increased temperature, the Humber population exhibited signs of cellular stress and damage. Our findings using the new annotated genome offer novel insights into the molecular arsenal of acid-base regulation which aids in predicting the impacts of an increasingly acidified and unstable ocean, and to transfer this knowledge to investigate these mechanisms in species with less tolerance.

genomics↗

bioRxiv2024

Nanopore Direct RNA Sequencing Reveals Virus-Induced Changes in the Transcriptional Landscape in Human Bronchial Epithelial Cells

Direct RNA nanopore sequencing data reveals changes in gene expression, polyadenylation, splicing, m6A methylation, and pseudouridylation in response to influenza virus exposure of primary human bronchial epithelial cells. This study focuses on the epitranscriptomic profile of genes in the host immune response. In addition to polyadenylated noncoding RNA, we purified and sequenced nonpolyadenylated noncoding RNA and observed changes in expression, N6-methyl-adenosine (m6A), and pseudouridylation ({Psi}) in these novel RNA. Two recently discovered lincRNA with roles in immune response, Chaserr and LEADR, are predicted in the analysis of the sequencing data to be highly methylated in response to influenza exposure. Several H/ACA type snoRNAs that guide pseudouridylation are decreased in expression in response to influenza, and there is a corresponding predicted decrease in the pseudouridylation of two novel lncRNA. Thus, novel epitranscriptomic changes revealed by direct RNA sequencing with nanopore technology provide unique insights into the host epitranscriptomic changes in epithelial gene networks that respond to influenza virus exposure.

bioinformatics↗

bioRxiv2023

Consequences of directly- and indirectly-experienced heat stress in a mutagenic environment

Climate change increases the frequency and duration of heat events. Negative effects of heat stress may be exacerbated through the action of social metabolites between aquatic animals. Whilst early life stages are vulnerable to stress-induced damage, they deploy cellular mechanisms to protect cells against mutagens such as ultraviolet rays (UV). Little is known about the fate of fish embryos which have experienced heat stress in a mutagenic environment. The present study exposed zebrafish embryos to one of three stress history treatments consisting of direct heat stress (TS+UV), the social context of heat stress via social metabolites (SM+UV), and their combination in TS+SM+UV before a UVB/UVA damage/repair assay. We measured phenotypic and transcriptomic responses to these treatments, and estimated mutational damage through DNA mutation frequencies and RNA integrity values. Compared to UV-treated controls (C+UV), the social context of heat stress history preceding the UV assay altered keratin and cell structuring-related pathways, associated with longer embryos with over-developed pericardia displaying behavioural hypoactivity. Relative to C+UV, direct heat stress history preceding UV exposure had a hormetic effect by stimulating the cellular stress response and facilitating DNA repair, which rescued embryos from subsequent UV damage and improved their apparent fitness. However, heat stress combined with social metabolites overwhelmed embryos in the UV assay, which annihilated the hormetic effect, introduced mutations, and lowered their apparent fitness. Whilst generated in the laboratory, these findings provide an important baseline for understanding the consequences of heat stress history in natural environments, where heat stress occurs within a social context. HighlightsO_LIHeat stress had a hormetic effect against UV damage, by stimulating the heat shock response, antioxidants, and DNA repair. C_LIO_LIThe heat hormetic effect protected and/or rescued embryos from UV damage by reducing single nucleotide variants observed in RNA, lowering malformations, and accelerating development. C_LIO_LIHeat-stressed embryos released social metabolites that initiated keratin, immune, and cellular structuring responses in receivers, in turn increasing body sizes but without reducing UV-induced malformations. C_LIO_LIHeat combined with social metabolites overwhelmed embryos in response to UV, reducing fitness-relevant performance. C_LIO_LIHeat stress during early embryogenesis led to differential fitness-relevant outcomes showing a nonlinear relationship with stress intensity. C_LI Summary statementSublethal heat stress protects zebrafish embryos in a mutagenic environment, but this protective effect is lost when zebrafish embryos additionally stress each other via chemical cues. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=84 SRC="FIGDIR/small/560724v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@a6445org.highwire.dtl.DTLVardef@3cfc64org.highwire.dtl.DTLVardef@1de41c6org.highwire.dtl.DTLVardef@b06269_HPS_FORMAT_FIGEXP M_FIG C_FIG

ecology↗

bioRxiv2022

ROCK2 Knockout Improves Proliferation Rate in a Cellular Model of Down Syndrome

In a cellular model of Down Syndrome, hTERT immortalized RPE-1 (human retinal pigment epithelial-1) cells carrying an extra copy of chromosome 21 exhibit reduced fitness, in part, as an increase in doubling time (or a reduction in cell proliferation rate) in culture. ROCK2 (Rho associated coiled-coil containing kinase 2) was identified in a whole genome CRISPR knockout (KO) screen designed to identify genes and pathways that could be therapeutically targeted to improve cell proliferation (Replogle JM, et al. manuscript in preparation). ROCK2 KO cell lines of both RPE-1 euploid and trisomy 21 aneuploid cells were created using CRISPR. Trisomy 21 ROCK2 KO cell lines showed a modest increase in cell proliferation rate compared to the parental aneuploid cells, similar to the relative effect that ROCK2 knockout had in the whole genome CRISPR screen. Euploid ROCK2 KO cell lines showed no difference in growth rate vs their ROCK2 expressing counterparts. Changes in doubling time in response to two pharmaceutical ROCK inhibitors, Fasudil and Y27632, also showed the same modest increase in cell proliferation rate in the trisomy 21 cells. The actin cytoskeleton, a target of ROCK2 regulation, exhibited long stress fibers that aligned across multiple contiguous cells in confluent trisomy 21 ROCK2 KO cells compared to the disorganized stress fibers of the parental trisomy 21 cells with normal ROCK2 expression.

cell biology↗

bioRxiv2022

Heat induces multi-omic and phenotypic stress propagation in zebrafish embryos

Heat alters biology from molecular to ecological levels, but may also have unknown indirect effects. This includes the novel concept that animals exposed to abiotic stress can induce stress in naive receivers. Here, we provide a comprehensive picture of the molecular signatures of this process, by integrating multi-omic and phenotypic data. In individual zebrafish embryos, repeated heat peaks elicited both a molecular response and a burst of accelerated growth followed by a growth slow-down in concert with reduced responses to novel stimuli. Metabolomes of the media of heat treated vs. untreated embryos revealed candidate stress metabolites including sulphur-containing compounds and lipids. These stress metabolites elicited transcriptomic changes in naive receivers related to immune response, extracellular signalling, glycosaminoglycan/keratan sulphate, and lipid metabolism. Consequently, non heat-exposed receivers (exposed to stress metabolites only) experienced accelerated catch-up growth in concert with reduced swimming performance. The combination of heat and stress metabolites accelerated development the most, mediated by apelin signalling. Our results prove the concept of indirect heat-induced stress propagation towards naive receivers, inducing phenotypes comparable to those resulting from direct heat exposure, but utilising distinct molecular pathways. Group-exposing a non-laboratory zebrafish line, we independently confirm that the glycosaminoglycan biosynthesis-related gene chs1, and the mucus glycoprotein gene prg4a, functionally connected to the candidate stress metabolite classes sugars and phosphocholine, are differentially expressed in receivers. This hints at production of Schreckstoff-like cues in receivers, leading to further stress propagation within groups, which may have ecological and animal welfare implications for aquatic populations in a changing climate. Significance StatementAquatic animals utilise chemicals to mediate adaptive behaviours. For instance, predated fish release chemical cues that elicit antipredatory responses in naive receivers. But whether abiotic factors such as heat likewise alter chemical communication has received little focus. Here, we uncover a novel dimension of chemical communication -- heat-stressed donors can induce stress in naive receivers. We show that heat activates molecular stress responses, leading to the release of distinct stress metabolite classes into the environment. These stress metabolites alter the transcriptome of receivers, resulting in faster development and hypoactivity. Heat combined with stress metabolites had the largest effect, highlighting that abiotic stress, experienced both directly and indirectly, can alter chemical communication and affect embryonic development. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=83 SRC="FIGDIR/small/508176v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@1e44b4borg.highwire.dtl.DTLVardef@10b6878org.highwire.dtl.DTLVardef@1f7c3bforg.highwire.dtl.DTLVardef@15436bc_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIWe elucidate the mechanism for a novel dimension of the heat stress response -- chemical communication from heat-stressed donors that induces stress in naive receivers -- constituting a positive feedback loop C_LIO_LIRepeated heat stress induces a cellular and cortisol stress response and alters the phenotype of zebrafish embryos C_LIO_LIHeat-stressed embryos release stress metabolites enriched in lipids and sulphur-containing organo-oxygen compounds C_LIO_LIIn combination, heat and stress metabolites induced 47% distinct differentially expressed genes, with many related to organ development C_LIO_LIThese stress metabolites alter the transcriptome and induce both faster development and hypoactivity in naive receivers, a similar response to that of heat stress itself C_LI

molecular biology↗

bioRxiv2019

Abiotic environmental adaptation in vertebrates is characterized by functional genomic constraint

Understanding the genomic basis of adaptation to different abiotic environments is important for understanding organismal responses to current short-term environmental fluctuations. Using functional and comparative genomics approaches, we here investigated whether genomic adaptation to a set of environmental parameters is contingent across vertebrate genomes or, alternatively, contains an element of evolutionary constraint that would be evident through recurrent involvement of specific subsets of genes and functions in adaptation to similar environments. We first identified 200 genes with signatures of selection from transcriptomes of 24 species of lacertid lizards with known adaptations in preferred temperature, correlated with thermal environment experienced by these lizards in their range. In order to discern genes adapting to climate from other selective factors, we then performed a meta-analysis of 1100 genes with signatures of selection obtained from-omics studies in vertebrate species adapted to different abiotic environments. We found that this gene set formed a tightly connected interactome which was to 23% enriched in predicted functions of adaptation to climate and to 18% involved in organismal stress response. We found a much higher degree of recurrent use of identical genes (43.6%) and functional similarity than expected by chance, and no clear division between genes used in ectotherm and endotherm physiological strategies. 171 out of 200 genes of Lacertidae were part of this network, indicating that a comparative genomic approach can help to disentangle genes functionally related to adaptation to different abiotic environments from other selective factors. These results furthermore highlight an important role of genomic constraint in adaptation to the abiotic environment, and narrows the set of candidate markers to be used in future research on environmental adaptability related to climate change.\n\nSignificance Statement / Nontechnical summaryWhile the convergent evolution of phenotypes in similar environments is a well-studied phenomenon, the genomic basis of such common phenotypes and physiologies is still enigmatic. The prevalent notion is that re-use of the same genes to adapt to similar environments in different species is about as likely as winning the lottery - but organismal systems are also, to some extent, comparable between different species such as man and fruit fly through shared genes and gene functions. In this paper, we test whether constraint or contingency is more prevalent in genomic adaptation of vertebrates to aspects of their abiotic environment. We find evidence for strong functional constraint and stress responsiveness of the genes involved, which might help understand how currently experienced stress under changing climates may result in future adaptation.

evolutionary biology↗

bioRxiv2018

Biodiversity trends are stronger in marine than terrestrial assemblages

Human activities have fundamentally altered biodiversity. Extinction rates are elevated and model projections suggest drastic biodiversity declines. Yet, observed temporal trends in recent decades are highly variable, despite consistent change in species composition. Here, we uncover clear spatial patterns within this variation. We estimated trends in the richness and composition of assemblages in over 50,000 time-series, to provide the most comprehensive assessment of temporal change in biodiversity across the planet to date. The strongest, most consistent pattern shows compositional change dominated by species turnover, with marine taxa experiencing up to fourfold the variation in rates of change of terrestrial taxa. Richness change ranged from no change to richness gains or losses of ~10% per year, with tropical marine biomes experiencing the most extreme changes. Earth is undergoing a process of spatial reorganisation of species and, while few areas are unaffected, biodiversity change is consistently strongest in the oceans.

ecology↗

bioRxiv2018

The geography of the Anthropocene differs between the land and the sea

O_LIClimate change and other anthropogenic drivers of biodiversity change are unequally distributed across the world. The geographic patterns of different drivers, and the spatial overlap among these drivers, have important implications for the direction and pace of biodiversity change, yet are not well documented. Moreover, it is unknown if the geographic patterns of drivers differ between the terrestrial and marine realm, as expected due to marked differences in how humans interact with the land and ocean. C_LIO_LIWe compiled global gridded datasets on climate change, land-use, resource exploitation, pollution, species invasions, and human population density. We used multivariate statistics to examine the spatial relationships among the datasets and to characterize the typical combinations of drivers experienced by different parts of the world. C_LIO_LIWe found stronger positive correlations among drivers in the terrestrial than in the marine realm, leading to areas of high intensities of multiple drivers on land. Climate change tended to be negatively correlated with other drivers in the terrestrial realm (e.g., in the tundra and boreal forest with high climate change but low human use and pollution) whereas the opposite was true in the marine realm (e.g., in the Indo-Pacific with high climate change and high fishing). C_LIO_LIWe show that different regions of the world can be defined by anthropogenic threat complexes (ATCs), distinguished by different sets of drivers with varying intensities. The ATCs can be used to test hypothesis about the pattern of biodiversity change, especially the joint effects of multiple drivers. More generally, our global analysis highlights the broad conservation priorities needed to mitigate the effects of anthropogenic change on biodiversity responses, with different priorities emerging on land and in the ocean, and in different parts of the world. C_LI

ecology↗

bioRxiv2018

Limits to anatomical accuracy of diffusion tractography using modern approaches

Diffusion MRI fiber tractography is widely used to probe the structural connectivity of thebrain, with a range of applications in both clinical and basic neuroscience. Despite widespread use, tractography has well-known pitfalls that limits the anatomical accuracy of this technique. Numerous modern methods have been developed to address these shortcomings through advances in acquisition, modeling, and computation. To test whether these advances improve tractography accuracy, we organized the ISBI 2018 3D Validation of Tractography with Experimental MRI (3D-VoTEM) challenge. We made available three unique independent tractography validation datasets - a physical phantom and two ex vivo brain specimens - resulting in 176 distinct submissions from 9 research groups. By comparing results over a wide range of fiber complexities and algorithmic strategies, this challenge provides a more comprehensive assessment of tractographys inherent limitations than has been reported previously. The central results were consistent across all sub-challenges in that, despite advances in tractography methods, the anatomical accuracy of tractography has not dramatically improved in recent years. Taken together, our results independently confirm findings from decades of tractography validation studies, demonstrate inherent limitations in reconstructing white matter pathways using diffusion MRI data alone, and highlight the need for alternative or combinatorial strategies to accurately map the fiber pathways of the brain.

neuroscience↗