BMC Biology

During meiosis, homologous chromosomes pair to form synaptonemal complexes (SCs) and exchange genetic material through a process known as meiotic recombination. First, programmed DNA double-strand breaks form, followed by the assembly of recombination foci on SCs. These foci mark the sites of recombination intermediates and future crossovers. Distributions of recombination foci along SCs have been studied in many eukaryotes, revealing the interplay between recombination patterns and genome evolution. However, in fish, data on recombination patterns are scarce, and, for the majority of groups, completely absent. Here, we measure the positions of MLH1 foci in 3,504 SCs from 219 male meiotic cells of an African annual killifish Nothobranchius virgatus, a representative of a genus with remarkable karyotype and genome diversity, and present a detailed statistical analysis of its recombination patterns. We found that, in contrast to the several other fish species characterised to date, recombination in N. virgatus occurs across almost entire chromosome arms, excluding (peri)centromeres and telomeres. In the longest SCs, we observed a proximal and a distal peak of the recombination focus frequency and explained the peaks by chromosome pairing dynamics. We also revealed the typical positions of focus pairs, demonstrated interference between foci, with the minimal interfocus distance of 4 m, and described regions of the total recombination suppression near centromeres and telomeres. In sum, our study provides a detailed analysis of recombination patterns in a killifish with a fully acrocentric karyotype and contributes to cytogenomic and statistical methodology for future exploration of meiotic recombination patterns.

Cleptoparasitism, or brood parasitism, is a striking behavioral strategy observed in approximately 13% of all bee species, yet its genomic underpinnings remain largely unexplored. We present the first high-quality genome assembly of the Neotropical cleptoparasitic bee Coelioxoides waltheriae (Nomadinae), a species that parasitizes the nests of Tetrapedia diversipes. The final assembly comprises 194.8 Mbp across 388 contigs, with an N50 of 1.47 Mbp and 97.4% BUSCO completeness, representing the second smallest genome among cleptoparasitic bees. Repetitive elements constitute only 14.6% of the genome, suggesting that its compact size is primarily driven by repeat reduction rather than gene loss. Comparative genomic analyses across 42 hymenopteran species revealed a pronounced contraction bias in gene family size changes in C. waltheriae (expansion ratio of 13.66%), a pattern also observed in other cleptoparasitic lineages. Expanded orthogroups were enriched for cuticle-related genes (e.g., PiggyBac transposases) potentially linked to host infiltration and defense, while contracted orthogroups showed significant reductions in sensory perception (e.g., odorant receptors), detoxification (e.g., cytochrome P450), and metabolic genes, reflecting the reduced ecological demands of a parasitic lifestyle. Furthermore, non-target DNA analysis identified associations with Roubikia mites (a known symbiont of its host), as well as fungi and bacteria, providing ecological context for this species. Our findings establish a critical genomic reference for cleptoparasitic bees, demonstrating that the evolution of parasitism is associated with targeted gene family contractions in sensory and metabolic functions alongside expansions in cuticle and transposable element-related genes, offering new insights into the genomic signatures of behavioral specialization.

The nematode Caenorhabditis elegans was the first metazoan to have its genome completely sequenced and assembled. Since that time, researchers have continuously updated the reference genome and manually curated its approximately 20,000 genes. The closely related species, Caenorhabditis briggsae, has served as a comparative model because of its similar morphology, mode of reproduction, and patterns of intra-species genetic variation. However, the genomic resources for C. briggsae lag behind C. elegans, hindering comparative genomics studies between the species. Decades of experimentation have been performed in the AF16 reference strain genetic background, so we obtained high-coverage long-read sequencing and high-throughput chromosome conformation capture data to create an updated reference genome for an isogenic derivative of AF16, named CGC2. The CGC2 genome is vastly improved relative to the existing AF16 assemblies, with no unplaced sequence, no gaps, and telomere-to-telomere contiguity. To provide genomic resources for CGC2, we exploited deep RNA-seq libraries from all developmental stages to predict protein-coding gene annotations comparable in accuracy and completeness to the existing AF16 gene models. We also performed lift-over of 108 validated insertion-deletion variants to the updated coordinate system of the CGC2 genome to facilitate future mappings of mutations. In summary, we present an updated reference genome for the canonical AF16 reference strain with improved genomic resources to enable high-quality intra- and inter-species comparative studies.

Some filamentous plant-pathogenic fungi have comparably large genome sizes within the fungal kingdom due to the proliferation of transposable elements (TEs). Blumeria hordei (Bh), the causal agent of the powdery mildew disease on barley, is a filamentous obligate biotrophic fungus. Compared to other ascomycetes, it contains a low number of genes but a high genomic TE content of approximately 75%. Yet, a comprehensive understanding of the contribution of TEs to the RNA and protein landscape of Bh is lacking. Here, we use Bh as a model to study transcripts and proteins derived from genes and individual TEs. Therefore, we created two high-quality genome assemblies of the German Bh isolate TUM1 and the Australian Bh isolate AUS1. We applied deep proteomics with mass spectrometry, long-read and short-read sequencing on both DNA and RNA. Based on these multi-omic resources, we completed nearly gapless genome assemblies, new gene and TE annotations, and effector predictions. Using long-read RNA sequencing, we detected extensive co-transcription of TEs and genes as TE-gene chimeric transcripts. We identified previously unpredicted splice variants or genes, partially supported by proteomics. The intergenic and TE genomic space of Bh TUM1 gives rise to thousands of transcripts and several novel TE-derived proteins that lack from previous TE protein predictions. Together, this supports an existing potential for expression of novel transcripts and proteins from highly abundant TEs in the Bh genome.

The rodent accessory olfactory system (AOS) detects chemosignals emitted by conspecifics and other species to support beneficial behaviors. Peripheral vomeronasal sensory neurons (VSNs), the AOS chemical sensors, detect fecal bile acids in patterns that have unknown significance to the animal. We used a combination of mass spectrometry and VSN calcium imaging to investigate the AOS capacity to use bile acid information to discriminate between fecal samples from captive reptiles and mice with varying gut microbiome states. Mass spectrometry analysis revealed bile acid patterns that distinguished biologically relevant samples from one another, representing theoretical discrimination axes. We measured VSN response patterns to bile acid stimuli aligned with theoretical discrimination axes. We found that VSNs perform stimulus "whitening" via an inverse relationship between natural bile acid abundance and population response magnitude. VSNs showed maximum sensitivity to taurine-conjugated bile acids, which have high theoretical discriminatory value, but were found at low natural abundance levels. Individual taurine-conjugated bile acids drove threat assessment behavior when added to familiar mouse fecal extracts, suggesting high behavioral significance. Finally, we analyzed the degree to which the AOS utilizes the theoretical information about species, diet, and gut microbiome status from bile acids. We found that VSN tuning patterns align with theoretical axes for discriminating reptilian predators from vegetarians, and between mice with different gut microbiome states. VSN tuning was especially well-aligned with the information available about conspecific gut microbiome status. These results show that AOS bile acid chemosensation supports discrimination of multiple biologically relevant states. Short abstractThe rodent accessory olfactory system (AOS) detects fecal bile acids via combinatorial codes with unknown biological significance. We investigated whether AOS bile acid chemosensation supports species and gut microbiome evaluation using mass spectrometry, calcium imaging in vomeronasal sensory neurons (VSNs), and analytical modeling. Bile acid excretion patterns theoretically supported discrimination of reptilian predators from vegetarians, and germ-free mice from conventionally raised counterparts. VSNs demonstrated stimulus "whitening" via an inverse relationship between natural bile acid abundance and population response magnitude. VSNs had highest sensitivity to taurine-conjugated bile acids, a novel class of chemosignals that elicited behavioral aversion. VSN tuning aligned with ideal discrimination axes, which was especially strong for gut microbiome-associated bile acid abundance patterns. These results show that AOS bile acid chemosensation supports discrimination of multiple biologically relevant states.

The high efficiency of genome editing presents a challenge when modifying genes associated with viability, welfare, or fertility issues, as implementation of the technology frequently results in mosaic animals with bi-allelic mutations. Combining deactivated Cas9 (dCas9) with Cas9 has been proposed as a strategy to protect one of the two target alleles from editing. We piloted this strategy with 11 genes that are reported as homozygous lethal or associated with welfare issues. We showed that the viability of founders was significantly increased when using 80:20 or 90:10 dCas9:Cas9 ratios, whereas the 70:30 ratio did not yield an equivalent protective effect. The associated overall production rate of mutated founder per manipulated embryo was significantly higher for the 80:20 ratio. Concomitantly, an increased proportion of dCas9 was associated with a significant increase in retention of unedited target alleles but, importantly, did not hinder germline transmission. In addition, editing genes in a paralog cluster with a combination of dCas9 and Cas9 reduced unwanted off-target editing, illustrating a further potential applicability of this approach. This study defines the optimal ratio between dCas9 and Cas9 for strategies aimed at achieving mono-allelic mutations within mosaic founders and proposes a means to reduce the incidence of off-target effects in experiments with limited gRNA options.

Octopamine is involved in a variety of different physiological and behavioral mecha-nisms in Drosophila melanogaster. Throughout the life cycle of the fruit fly, from the larva to the adult, octopaminergic neurons in both the central and the peripheral nerv-ous system target a multitude of neurons and even non-neuronal tissues, making it challenging to analyze individual mechanisms of octopamine function. One approach to deconstructing this complex system is to examine the postsynaptic components of signal transmission. In Drosophila, octopamine interacts with six distinct G-protein-coupled receptors. For some of these receptors, expression maps and functional im-plications have been described. In contrast, other receptors have been neglected, partly due to the lack of suitable genetic tools. Here, for the first time, we compiled a complete set of mutant lines of all known octopamine receptors, all generated using the same genetic tool, the recently established Trojan Exon system. It integrates the Gal4/UAS binary expression strategy while simultaneously impairing receptor func-tion. This enabled us to generate a comprehensive anatomical map of receptor ex-pression in the larva and, at the same time, analyze the function of individual octopa-mine receptors during larval development, chemosensory perception and locomotion. All octopamine receptors (Oamb, Oct2R, Oct{beta}1R, Oct{beta}2R, Oct{beta}3R, and Oct-TyrR) showed extensive signal in the central nervous system. The same was found for the peripheral nervous system, with the exception of Oct{beta}2R, which showed pronounced expression in the somatic muscles. We also observed a previously undescribed role of Oct{beta}1R, Oct{beta}3R, and Oct-TyrR in larval hatching and in the survival of larvae and pupae. Molecular evaluation of the Trojan Exon octopamine lines supports our analy-sis. In addition, we combined the experimental results with gene expression data from the different development stages of Drosophila melanogaster and from different tis-sues and cell populations throughout the body. Overall, we compiled, analyzed and validated a complete set of octopamine lines which, together with gene expression analysis, provides a basis for further functional studies on the larval octopaminergic system.

The origin of eukaryotes is a key event in the evolution of cellular life hypothesized to involve a symbiotic integration between a member of the Asgard archaea and the Alphaproteobacteria. Recent work has provided evidence for additional genetic input from other prokaryotes to the eukaryotic proteome yet the extent and sources of these contributions remain debated. Here we aimed to further resolve the prokaryotic origins of eukaryotic genes to inform our understanding of eukaryogenesis. Specifically, we developed a phylogenetic framework to investigate the origins of eukaryotic gene families associated with metabolism and informational processing for comparison. We found that informational processing genes were predominantly derived by archaea whereas eukaryotic metabolism is highly chimeric in its origin. In contrast to previous studies, we report a substantial number of archaeal origins of diverse metabolic enzymes including key metabolic regulators. This highlights an overlooked participation of archaeal metabolism and pinpoints potential metabolic integrations during eukaryogenesis. Apart from the alphaproteobacterial contributions to the eukaryotic metabolism, we found an additional dominant phylogenetic signal of genes potentially derived from Myxococcota, especially for gene families associated with lipid metabolism. By systematically analysing the origins of eukaryotic metabolism, this research offers novel insights into the origin of eukaryotic membranes and refine our current models for the origin of the eukaryotic cell.

Immunoglobulin genes are a central component of jawed-vertebrate adaptive immunity. A previous study showed that the blunt-snouted clingfish Gouania willdenowi lacks immunoglobulin genes and T-cell receptor gamma/delta loci, while retaining T-cell receptor alpha/beta genes, MHC genes, and RAG1 /RAG2. Here I extend that observation to the family Gobiesocidae using all seven chromosome-level Gobiesocidae genome assemblies currently available. Manual tblastn and synteny-guided searches found no convincing immunoglobulin heavy-chain or light-chain loci in G. willdenowi, Gouania pigra, Gobiesox punctulatus, Apletodon dentatus, Lepadogaster candolii, Lepadogaster purpurea, or Diplecogaster bimaculata. Thus, the absence of antibody genes is best interpreted as a root-level character of clingfishes. The latest seven-species screen of 40 additional immune-associated genes shifts the broader interpretation in the same direction: the B-cell/adaptive core genes CD79A, CD79B, CIITA, TNFRSF13B, and TNFSF13B lack strong tblastn support in all sampled Gobiesocidae, and 37 of the 40 tested targets show an all-zero binary pattern at the presence threshold. Only IL21R.1, TYROBP, and TNFRSF11A show strong hits in one or more species. I therefore interpret the principal immune-gene erosion as occurring at or near the Gobiesocidae root rather than as a recent Gouania-specific process, while keeping weak, paralog-sensitive, and patchy loci provisional. RAG2 comparisons show a shared Gobiesocidae PHD-domain C-to-S replacement in the zinc-binding motif, with apparently intact RAG2 coding sequence. A family-wide TRG/TRD screen did not recover TRGV V segments or accepted TRDC constant-region exons, but it did detect TRGC-like constant exons in several genomes. These TRGC-like sequences are probably not canonical TRG constant exons without further validation, so I treat the gamma/delta system as eroded or rearranged rather than as a complete root-level loss equivalent to the Ig loss. The RAG2 variant provides a plausible molecular context for antigen-receptor remodeling, but it is not evidence that RAG genes are pseudogenized, because TCR alpha/beta, MHC genes, and RAG1 /RAG2 are retained. Gobiesocidae are therefore best described as a vertebrate family with ancestral loss of canonical immunoglobulin genes and associated root-level erosion of B-cell and immune-related genes, not as a lineage lacking adaptive immunity in its entirety. HighlightsO_LISeven chromosome-level Gobiesocidae genomes lack convincing canonical IgH and IgL loci. C_LIO_LIThe strongest non-Ig losses map to the B-cell/adaptive core: CD79A, CD79B, CIITA, TNFRSF13B, and TNFSF13B. C_LIO_LITCR alpha/beta, MHC genes, and RAG1 /RAG2 are retained, so Gobiesocidae should not be described as lacking adaptive immunity in full. C_LIO_LIA shared Gobiesocidae RAG2 PHD-domain C-to-S variant provides candidate molecular context for antigen-receptor remodeling. C_LI

The phylum Mollusca constitutes one of the most taxonomically and morphologically diverse animal clades; however, the genomic exploration of this group has been hampered by fragmented and taxonomically incomplete transcriptomic resources. To address this fundamental limitation, we present MolluscaGenes, a centralized database that unifies transcriptomes from 299 molluscan species spanning all eight recognized classes, encompassing a broad array of tissues and developmental stages. MolluscaGenes provides searchable databases via BLAST and DIAMOND alongside a suite of 196 molluscan-optimized Hidden Markov Models (HMMs) for sensitive protein family identification. To demonstrate the utility of this resource, we performed a comprehensive phylum-wide characterization of the nicotinic acetylcholine receptor (nAChR) superfamily, recovering 3,586 sequences from over 190 species and resolving 15 distinct phylogenetic clades. This analysis revealed substantial lineage-specific expansions across multiple molluscan classes, the identification of novel clades with substitutions in canonical ligand-binding residues, and the evolutionary placement of chemotactile receptors (CRs) and CR-like sequences as predominantly cephalopod clades within the broader nAChR phylogeny. MolluscaGenes constitutes a foundational resource that will accelerate the elucidation of the unique biology and evolutionary history of Mollusca.

The pea aphid (Acyrthosiphon pisum) is an important model organism for studying complex biological traits, including wing polyphenism and host-symbiont interactions, yet its regulatory genomic landscape remains largely uncharacterized. Here we present the first genome-wide chromatin accessibility map of the pea aphid, generated using the assay for transposase-accessible chromatin followed by sequencing (ATAC-seq). We profiled open chromatin regions (OCRs) in adult brains and late-stage embryos from winged and wingless morphs maintained under solitary or crowded conditions. We also paired ATAC-seq with RNA-seq in embryonic samples to examine the relationship between chromatin accessibility and gene expression. Libraries showed a high abundance of reads from the aphid endosymbionts Spiroplasma and Buchnera, reflecting preferential Tn5 transposase insertion into nucleosome-free bacterial DNA. After computational removal of these reads, the remaining aphid-mapping libraries displayed hallmarks of high-quality ATAC-seq data. We identified a consensus set of 37,127 OCRs enriched at promoters and distal regulatory elements, with substantial overlap with computationally predicted enhancers and enrichment for transcription factor binding motifs. Tissue identity was the dominant driver of chromatin variation, accounting for 85% of variance along the first principal component, with 19,513 differentially accessible regions distinguishing brain from embryo samples. By contrast, differences associated with wing morph or crowding treatment were modest. Promoter accessibility was significantly and positively correlated with gene expression genome-wide. Together, these data constitute a foundational regulatory genomics resource for the pea aphid and establish a framework for mechanistic studies of gene regulation in this ecologically and economically important insect.

Animals continuously evaluate environmental cues to guide approach-avoidance decisions, with internal states like hunger dynamically shaping how stimuli are acted upon. While most studies examine the valence-switching of stimuli from appetitive to aversive using simplified or ambiguous stimuli, we leveraged a system in which a single prey contains both appetitive and aversive features. The nudibranch Berghia stephanieae, is a specialist predator of the sea anemone, Exaiptasia diaphana. These nudibranchs must resolve conflicting signals where chemical cues signal food, while contact can result in injury or death. The danger posed by Exaiptasia was described and quantified through direct counts of nematocysts fired into Berghia and multiple instances where the Berghia was captured and consumed by its prey. To test how internal state influenced the perception of stimuli from prey we recorded predatory behavior of Berghia after different periods of food deprivation. We found that the olfactory cues from prey were attractive to Berghia, even when animals were sated, and usually led to a contact-mediated investigation of prey. Hunger independently modulated olfactory and contact cue valence at different internal states and time scales of food deprivation. Hunger specifically altered the threshold for avoidance following contact with prey, indicating that somatosensory and chemotactile cues are modulated by hunger unlike olfactory cues. Our results highlight how internal state and sensory modality interact to shape decision making in a biologically relevant, high-risk predation context.

Among mammals, spiny mice (Acomys spp.) exhibit the unique capacity to regenerate parts of their nervous system. Studying this phenomenon has the potential to reveal new targets that can slow or halt human neurodegenerative disorders. Unfortunately, research tools (e.g., transgenic lines, gene delivery vehicles) are lacking compared to those available for other rodent models. Here, we tested systemic adeno-associated viral vectors (AAVs) in Acomys dimidiatus and identified three promising candidates: X1.1, CAP-Mac, and MaCPNS1. Characterizing their tropism following intravenous delivery, we found that in the brain, MaCPNS1 and X1.1 primarily transduced astrocytes. In the peripheral nervous system, MaCPNS1 efficiently transduced dorsal root ganglia, axon bundles of the ear pinnae, and enteric neurons throughout the gastrointestinal tract. As a proof-of-concept, we used MaCPNS1 to chemogenetically modulate the activity of enteric neurons, successfully decreasing gastric motility in vivo and increasing colonic motility ex vivo. We expect these findings to enable functional studies of the uniquely regenerative nervous system of Acomys, which may in turn help advance neuroregenerative therapeutics for humans. Summary StatementIdentification of an AAV tool to efficiently deliver transgenes to the central and peripheral nervous systems of spiny mice enables functional studies of the nervous system in a mammalian model of regeneration.

Long-term, automated tracking of group-housed social animals using RFID (radio frequency identification) is a promising approach in ethological neuroscience. However, low-frequency (LF) RFID, while long-established in the field, is constrained by its inherent low data rates, which lead to two critical limitations: (1) compromised spatiotemporal resolution, and (2) the inability to identify multiple tags (animals) simultaneously. To address these limitations, we developed eeeHive, a high-frequency (HF) RFID-based animal tracking system with a fully custom hardware architecture that enables high-speed, multiplexed antenna polling and concurrent multi-tag reading. The polling time per antenna in eeeHive was 5.9 ms, with an additional 8.2 ms read time per tag. We applied the system to track 24 mice for one week, and six common marmosets for seven weeks. The system successfully tracked individuals even within dense clusters, revealing complex behavioral traits characterized by spatial utilization, temporal dynamics, behavioral regularity, and inter-individual relationships. Additional tests with Japanese fire-bellied newts and Nile tilapia juveniles demonstrated comparable tracking performance in aquatic environments. Taken together, eeeHive overcomes the inherent limitations of conventional LF RFID, establishing a powerful HF RFID-based platform for fine-scale behavioral tracking of group-housed animals across terrestrial and aquatic species.

The black legged tick, Ixodes scapularis, is a vector of the bacterium that causes Lyme disease and several other illnesses, including anaplasmosis, babesiosis, and tick-borne encephalitis. Although high-quality genome annotations are available for I. scapularis, functional understanding of I. scapularis genes is limited. To address this, we developed a platform for genome-wide CRISPR-Cas9 knockout screening in I. scapularis cells. To evaluate the platform, we performed a screen to identify genes associated with cellular fitness, and screens for resistance to treatment with copper chloride, Antimycin A, or Destruxin A (DA), a cyclic hexadepsipeptide produced by the pathogenic fungus Metarhizium anisopliae. In each case, the screens implicate specific sets of conserved and non-conserved I. scapularis genes in relevant cellular functions, providing the first experimental evidence of function for a large set of I. scapularis genes. Altogether, in this first-of-its-kind effort for the arthropod subclass Acari, we present an unbiased genome-wide CRISPR-Cas9 knockout cell screening platform, related resources, and datasets that will be broadly useful to efficiently uncover cellular functions of I. scapularis genes.

Transposable elements are a highly diverse group of selfish genomic elements, prevalent across the tree of life, whose uncontrolled propagation poses a threat to genome stability. Recent studies have explored the evolution of Drosophila melanogaster transposable elements, their co-evolution with the host genome, and mechanisms that regulate their activity. However, little is known about their cross-species evolutionary patterns. Long terminal repeat (LTR) retrotransposons are the most active group of transposable elements in Drosophila. They are broadly separated into retroelements, which are active in the germline, and insect endogenous retroviruses that are active in the soma. Somatic elements are hypothesised to infect the germline through their acquisition of virus-derived proteins such as Envelope and sORF2, thus multiplying through successive generations. In this study, we curated the sequences of LTR retrotransposons in 249 drosophilid genomes, allowing us to study their evolution across these species and highlight their varying degrees of conservation. Furthermore, we reveal multiple instances of Envelope protein loss or inactivation that suggest shifts in the expression pattern of these transposons, likely accompanied by adopting different transcriptional control mechanisms. We contrast this with the evolutionary history of sORF2, which we found to be much more stable. Lastly, we examined variations in transposon LTR regions responsible for transcriptional regulation and use predictive modelling to suggest six transcription factors likely involved in their tissue-specific expression. Altogether, we reveal complex, interspecies evolutionary patterns of Gypsy-family LTR retrotransposons and highlight examples of their co-evolution with their host genome.

Background: Literature on the role of thermal discomfort (heat- and cold-stress) on in-vitro fertilization (IVF) outcomes are scarce and inconclusive. This multi-center research examines association between heat stress and IVF treatment outcomes in Andhra Pradesh, which is prone to year around chronic heat stress. Methods: IVF data were abstracted from clinical chart review of all patients from three IVF from centers 2019 to 2023, which included time-stamped data on each IVF procedure, demographics and pre-existing comorbidities. Weather data were acquired from the National Climatic Data Center (NCDC). IVF outcomes were modelled with respect to time-lagged exposure to ambient temperature stratified by hyper- and hypo-thermic conditions using Poisson and logistic regressions depending on the scale of IVF outcomes adjusting for confounders. Results: Heat stress peaked in June, which corresponded with elevated number of spontaneous abortions/miscarriage (SAM). Under hypo- and hyper-thermic conditions a unit increase ambient temperature was associated with an 11% higher and an 8% lower number of oocytes retrieved, respectively. Adjusting for confounders, a 10 degree F increase in two-day lag heat stress was associated with a 30% higher odds of SAM (odds ratio ~ 1.03; 95% CI = 1.001 to 1.068; p-value < 0.043), and odds of PTB were 3 times higher when three day-lagged heat index (HI) was greater than 35 degree C (odds ratio 1.13 to 7.99; p < 0.05). Conclusion. Our findings warrant strategies to engage IVF patients in mitigating their exposure to thermal discomfort before and during the treatment.

Widespread arthropod declines pose risks to ecosystem functioning and agriculture. Assessing this decline or potential remediation implies the need for standardized and scalable population monitoring. Image-based methods, including camera traps and citizen science programs, are increasingly used, but the volume of data collected requires automated analysis. Robust arthropod detection is essential for individual counting or fine-grained classification, yet current datasets and algorithms do not address the vast morphological diversity across arthropod species and often overlook the variety of photographic contexts, such as differences in background, lighting, and image composition, in which arthropods are captured. To address this gap, we developed an arthropod detection dataset, covering all terrestrial families present in France with available validated images on the iNaturalist platform (749 families). To achieve this, we employed an iterative workflow in which a YOLOv11 model pre-annotated images -- using one representative species per family-- followed by manual correction and model retraining. Repeating this process progressively reduced annotation effort and improved model accuracy. The final outcome consists of a publicly available curated detection dataset and a robust arthropod detector for natural background scenes. The detector achieves an F1-score of 0.91, demonstrating strong performance despite substantial interspecific morphological variation and heterogeneity in photographic contexts. We further demonstrated the taxonomical universality of the model showing high F1-score and IoU averaged at the class (0.79, 0.85) and order level (0.82, 0.86) and also a good detection generalizability (F1-score>0.90, IoU>0.83) on species, genera and families never encountered by the model during training. Finally, we show how this model can be improved to generalize to new datasets using data augmentation, complementary training data or fine-tuning and increase detection of small objects. In particular, we report performance of the improved models on three use cases largely used in non lethal insect monitoring: (i) diurnal pollinator monitoring through citizen science or (ii) flower and nocturnal insects monitoring through smartphone time-lapse of a UV-illuminated white panel. These results mark an important step toward automated analysis of arthropod images in natural contexts, from both large-scale automated monitoring approaches or from citizen science monitoring programs.

Arthropods exhibit an exceptional diversity of life histories, where developmental modes involve moulting stage progressions with changes ranging from the bare minimal to the dramatically transformative. While this variability drives many research questions aiming to understand evolutionary and developmental underpinnings of life history differences, it can complicate comparative analyses across taxa. However, this can be approached by applying a framework that defines metamorphosis as a post-embryonic stage progression characterised by substantial changes in morphology and adaptive landscape. Employing this framework with a phylogenomic dataset spanning 26 orders and encompassing four independently arising metamorphic lineages, we explore gene repertoire evolutionary dynamics potentially associated with metamorphosis in Pancrustacea. The approach contrasts gene family evolutionary dynamics inferred to have occurred in the last common ancestors of the metamorphic Insecta, Copepoda, Eucarida, and Thecostraca, with those of their sister lineages, as well as of descendent and ancestral nodes. The results reveal that the metamorphosis ancestors are characterised by an elevated number of gene family births and expansions. Expanded gene families share a set of commonly enriched biological processes across all metamorphosis ancestors, suggesting functional convergence by independent evolution of distinct gene families involved in embryonic and post-embryonic development and nervous system differentiation. Evolutionary modelling further highlights a subset of these families exhibiting signatures of adaptive, lineage-specific gene family size increases associated with metamorphic development. These families include genes implicated in neural and sensory development, segmentation, and moulting. These findings support a model of the evolution of pancrustacean metamorphosis where distinct gene families from a common functional toolkit expand and are co-opted into facilitating transitions to multi-phasic life cycles. This reframes the role of moulting in arthropod diversification to be recognised as an important reservoir of genetic change that can potentiate truly remarkable life history transitions.

The fungal cell wall is populated by proteins (CWPs), mostly uncharacterized, that show an atypical evolutionary behavior. Most CWPs are glycosylphosphatidylinositol(GPI)-proteins, followed by proteins with internal repeats (PIR), and non-covalently attached proteins that harbor carbohydrate binding domains (CBM). Several structural CWPs are initially bound to the same wall carbohydrates, but either covalently or non-covalently. However, it is not clear whether they work in the same way and if they are subjected to the same evolutionary constraints. In Neurospora crassa, CWPs ACW-1 (NCU08936) and NCW-3 (NCU07817) bind to {beta}-1,3-glucans through a GPI anchor or a predicted CBM-52 domain, respectively. Here, the evolutionary trajectories and functional roles of both CWPs were analyzed. Both proteins localized primarily to distal septa and hyphal wall surfaces. Morphological characterization and stress cell wall assays suggested that both proteins contribute to cell wall integrity, but NCW-3 likely plays a more prominent role. ACW-1 and NCW-3 homologues were predominantly identified in Ascomycota. ACW-1 displayed a broader distribution than NCW-3, whose homologues were largely restricted to Sordariales. Despite these differences, both protein families exhibited similar moderate global conservation and signatures of purifying selection within shared taxa. Nevertheless, a divergence gradient was identified within ACW-1, related to its tandem leucine-rich repeat (LRR) regions. A similar local accumulation of evolutionary change was not observed within NCW-3. These findings suggested that distinct CWP architectures can accommodate different patterns of sequence diversification despite sharing similar global evolutionary change.