Biology subjects

Moore, A. J.

Publications and source records attributed to Moore, A. J..

At least 19 recordsLinked to original sources

bioRxiv2026

Conserved genes with variable expression and function: Vasa, Piwi, and Dnmt1 in Oncopeltus fasciatus gametogenesis

The production of gametes is one of the universal processes of life and given millennia of evolution many of the core genes involved are expected to be highly refined and resistant to change. Here we examine the pattern of expression and functionally characterize three genes widely involved in gametogenesis: Vasa, Piwi, and Dnmt1. We examine their cellular location during both oogenesis and spermatogenesis in Oncopeltus fasciatus, a hemipteran insect, using fluorescent in situ hybridization chain reaction. In females, expression of Piwi was restricted to the trophocytes, but Vasa and Dnmt1 were expressed in developing ooctyes as well as the trophoctyes. In males, Piwi was expressed in the testis germline stem cells (GSCs), but Vasa and Dnmt1 expression was absent from these cells. Additionally, Piwi and Vasa were expressed in secondary spermatogonia and spermatocytes while Dnmt1 was predominantly expressed in the primary spermatogonia. We also functionally characterized their necessity for gametogenesis after RNAi-mediated gene expression knockdown. Vasa was not required for oogenesis but was required during spermatogenesis. Piwi and Dnmt1 were required for both oogenesis and spermatogenesis. These results were in contrast to their requirement for these processes from other organisms, which highlight the unexpected variation found in the processes and suggest that conservation depends on the level at which genes are examined: sequence, expression, or phenotypic and biochemical function. This suggests there is a more nuanced evolutionary story of conserved, yet plastic, gametogenic gene set in Metazoa that deserves further study across more organisms.

evolutionary biology↗

bioRxiv2026

The Brain Age Gap as a Predictor of Alcohol Initiation in Adolescence

BackgroundGrowing evidence suggests regional and network-level brain imaging features in late childhood are predictive of alcohol use in adolescence. However, the directionality of these effects (i.e. whether they reflect accelerated or delayed neuromaturation) are mixed. We applied a Brain Age Gap Estimation (BrainAGE) model to examine whether overall deviations from typical brain aging trajectories are predictive of (1) alcohol initiation and (2) use behaviour (experimentation versus binge drinking) in adolescence. MethodsData from the Adolescent Brain Cognitive Development study release 6.0 were used. Baseline (ages 9-11) structural imaging features (cortical volume, area, and subcortical volume) were used to estimate BrainAGE. Alcohol use was determined using self-report data from the Substance Use Interview and Timeline Follow-Back across follow-ups (waves 1-6; ages 10-17). Logistic generalized mixed effects models examined whether BrainAGE predicted group status between (1) non-initiators (n=3,639) and initiators (n=1,176), and; (2) experimentation (at least one full drink, no binge episodes; n=461) and binge drinking (at least one episode; n=438). ResultsWhen adjusting for age, sex, and pubertal status, a one-standard-deviation decrease in BrainAGE (equivalent to 1.64 years) at baseline was associated with a 9.5% increase in odds of alcohol initiation in adolescence. However, this effect did not survive adjustment for sociodemographic and prior alcohol exposure covariates. Further, BrainAGE did not discriminate between experimentation and binge drinking. ConclusionsFindings suggest BrainAGE in late childhood may reflect potential risk for alcohol initiation, but not behaviours, in adolescence. However, this association likely reflects complex interactions between brain structure and contextual factors, warranting further investigation.

neuroscience↗

bioRxiv2025

Rhesus macaques model human Mayaro virus disease and transmit to Aedes aegypti mosquitoes

BackgroundMayaro virus (MAYV) is a mosquito-borne alphavirus endemic to Latin America that causes fever and arthritis. Unlike the related chikungunya virus, MAYV has not caused widespread, human-amplified epidemics. One possible explanation is that human viremia levels are too low to support transmission to urban Aedes (Stegomyia) aegypti mosquitoes. We used rhesus macaques (RM) to model human-to-Ae. aegypti transmission and to further expand understanding of their relevance to human MAYV disease. Methodology/Principal FindingsTwelve RM were inoculated with a genotype D lineage MAYV strain using one of 3 doses: 7 log10 plaque forming units (PFU) intravenously (IV), 7 log10 PFU subcutaneously (SC), or 3 log10 PFU SC. Viremia was measured daily in plasma and RM were euthanized 10- or 12-days post-inoculation (dpi). On 2, 3, 5, and 7 dpi, Ae. aegypti were allowed to bloodfeed, incubated for 10 days, then dissected and tested to detect MAYV in tissues and saliva. RM developed infectious MAYV viremias lasting 3 days, peaking 1-2 dpi with titers ranging from 2-6 log10 PFU/ml. RM inoculated with 7 log10 PFU IV developed significantly higher viremias (area under the curve) than those receiving 3 log10 PFU SC. MAYV RNA was detected in muscle, lymphoid, central nervous, and cardiac tissues. RM showed no signs of fever or joint swelling but some developed mild rashes in areas distant from mosquito feeding sites and histologic inflammation was observed in joints and muscles. Only Ae. aegypti that fed on viremic RM 2 dpi became infected, with an overall infection rate of 48%. Among all mosquitoes that fed on RM 2 dpi, only 2% (4/217) had infectious MAYV in their saliva, suggesting transmission competence. Despite 11 of 12 RM transmitting MAYV to at least one mosquito, individual RM varied in infectiousness to Ae. aegypti, and mosquito cohort infection rates did not correlate with RM viremia levels. Conclusions/SignificanceRM exhibit short-lived MAYV viremias, broad tissue tropism, and mild joint and muscle inflammation, closely resembling human infection. While viremic RM can infect Ae. aegypti, the transmission window is narrow and transmission by Ae. aegypti is rare. The combination of a short infectious period in RM and low transmissibility of Ae. aegypti infected from RM may help explain the absence of widespread urban MAYV outbreaks. AUTHOR SUMMARYMayaro virus (MAYV) is a mosquito-borne virus found in Latin America that causes fever and joint pain, similar to chikungunya virus (CHIKV). However, unlike CHIKV, MAYV has not led to large outbreaks. One reason may be that levels of MAYV in human blood are too low for Aedes aegypti mosquitoes--known for spreading chikungunya, dengue, and Zika--to pick up and transmit the virus in cities. To better understand this, we studied rhesus macaques, a monkey species that serves as a model for how MAYV behaves in people. We tracked virus levels in their blood and tissues and observed mild joint and muscle inflammation, similar to Mayaro fever in people. Although the macaques were able to infect some Ae. aegypti mosquitoes, the transmission window was short, and only a few mosquitoes that became infected had virus in their saliva, suggesting transmission competence. This limited ability of urban mosquitoes to spread MAYV may help explain why major outbreaks have not occurred.

microbiology↗

bioRxiv2024

Embryological insights into the evolution of genome regulation using haploid and diploid whiteflies, Bemisia tabaci

The whitefly, Bemisia tabaci, is a hemipteran with a haplodiploid sex determination system, which provides a natural experiment for examining genome function in haploid and diploid embryos. Yet the embryogenesis of B. tabaci remains understudied. Our previous work has established a possible role of DNA methyltransferase 1 (Dnmt1) in genome stability. In this study we used maternal RNA interference (RNAi) and immunohistochemistry to study the complex dynamics between DNMT1 and ploidy during embryogenesis. We found that both haploid and diploid B. tabaci have a similar developmental timeline to other holometabolous insects. We also found that, like other obligatory haploid insects, ploidy does not affect developmental timing, suggesting that maternal factors play a greater role than ploidy in developmental timing. For embryos with reduced expression of Dnmt1, we found that the loss of DNMT1 disrupts blastoderm development and affects nuclei morphology in both haploid and diploid embryos. Our results suggest that DNMT1 is required for blastoderm development.

developmental biology↗

bioRxiv2023

Dmnt1 and Wnt in the production of oocytes

The function of methylation in insects and the DNA methyltransferase (Dnmt) genes that influence methylation remains uncertain. We used RNAi to reduce the gene expression of Dnmt1 within the whitefly Bemisia tabaci, a hemipteran species that relies on Dnmt1 for proper gametogenesis. We then used RNA-seq to test an a priori hypothesis that meiosis related genetic pathways would be perturbed. We generally did not find an overall effect on meiosis related pathways. However, we found that genes in the Wnt pathway, genes associated with the entry into meiosis in vertebrates, were differentially expressed. Our results are consistent with Dnmt1 knockdown influencing specific pathways and not causing general transcriptional response. This is a finding that is also seen with other insect species. We also characterized the methylome of B. tabaci and assessed the influence of Dnmt1 knockdown on cytosine methylation. This species has methylome characteristics comparable to other hemipterans regarding overall level, enrichment within gene bodies, and bimodal distribution of methylated/non-methylated genes. Very little differential methylation was observed, and difference of methylation were not associated with differences of gene expression. The effect on Wnt presents an interesting new candidate pathway for future studies.

genomics↗

bioRxiv2023

takeout gene expression is associated with temporal kin recognition

A key component of parental care is avoiding killing and eating your own offspring. Many organisms commit infanticide but switch to parental care at the time when their own offspring would be expected, known as temporal kin recognition. It is unclear how such indirect kin recognition is so common across taxa. One possibility is that temporal kin recognition can be achieved by altering a simple mechanism, such as co-opting the regulation of timing and feeding in other contexts. Here we determine whether takeout, a gene implicated in coordinating feeding, influences temporal kin recognition in the roundneck sexton beetle, Nicrophorus orbicollis. We find that takeout expression is not associated with non-parental feeding changes resulting from hunger, or in the general switch to the full parental care repertoire. However, beetles that accepted and provided care to their offspring had a higher takeout expression than beetles that committed infanticide. Together, these data support the idea that the evolution of temporal kin recognition may be enabled by co-option of mechanisms that integrate feeding behaviour in other contexts.

animal behavior and cognition↗

bioRxiv2023

In defense of Apocynaceae: inference on evolution of pyrrolizidine alkaloids from evolution of an enzyme in their biosynthetic pathway, homospermidine synthase

PremiseWhen enzymes encoded by paralogous genes produce identical specialized metabolites in distantly related plant lineages, it is strong evidence of parallel phenotypic evolution. Inference of phenotypic homology for metabolites produced by orthologous genes is not so straightforward, however, since orthologs may be recruited in parallel into novel pathways. Prior research on pyrrolizidine alkaloids (PAs), specialized metabolites of Apocynaceae, reconstructed evolution of homospermidine synthase (HSS), an enzyme of PA biosynthesis, and inferred a single origin of PAs because HSS enzymes of all known PA-producing Apocynaceae species are orthologous and descended from an ancestral enzyme with the predicted motif (VXXXD) of an optimized HSS. MethodsWe increased sampling, tested the effect of amino acid motif on HSS function, revisited motif evolution, and tested for selection to infer evolution of HSS function and its correlation with phenotype. Key resultsSome evidence supports a single origin of PAs: an IXXXD HSS, similar in function to VXXXD HSS, evolved in the shared ancestor of all PA-producing species; loss of optimized HSS occurred multiple times via pseudogenization and perhaps via evolution of an IXXXN motif. Other evidence indicates multiple origins: the VXXXD motif, highly correlated with the PA phenotype, evolved two or four times independently; the ancestral IXXXD gene was not under positive selection while some VXXXD genes were; substitutions at sites experiencing positive selection occurred on multiple branches in the HSS-like gene tree. ConclusionsComplexity of the genotype-function-phenotype map confounds inference of PA homology from HSS evolution in Apocynaceae.

evolutionary biology↗

bioRxiv2023

The critical role of Dmnt1 during spermatogenesis is not predictable, but knockdown does cause pervasive differential transcription.

Cytosine methylation and its machinery influence the gene expression of many eukaryotes; however, insects are an exception to this general tenet despite many lineages retaining methyltransferases and methylated genomes. Here, we tested the a priori hypothesis that perturbed genetic pathways will be associated with meiosis using transcriptomics because previous our work using Oncopeltus fasciatus shows that gametogenesis is interrupted at meiosis following knockdown of DNA methyltransferase 1 (Dnmt1). Testes, which are almost exclusively contain gametes at varying stages of development, were sampled at 7-days and 14-days following knockdown of Dmnt1 using RNAi. Using microscopy, we found actively dividing spermatocysts were reduced at both sampling points. However, we found limited support of perturbation for our predicted cell cycle and meiotic pathways and only at 14-days. We found that Gene Ontology terms had no preferential enrichment for meiosis-associated genes. Following our a priori tests, we used the full dataset to uncover further candidate pathways influenced by Dnmt1 knockdown. Very few genes were differentially expressed at 7-days, but nearly half were at 14-days. We did not find strong candidate pathways for how Dnmt1 knockdown was achieving its effect through Gene Ontology term overrepresentation analysis. Given the evidence from microscopy, we propose Dnmt1 knockdown results in condensed nuclei after mitosis-meiosis transition and then cellular arrest. This explanation posits that differential gene expression is a product of comparing healthy to arrested cells and is not a targeted response.

genomics↗

bioRxiv2022

Spatiotemporal variation in the competitive environment, with implications for how climate change may affect a species with parental care.

Burying beetles of the genus Nicrophorus have become a model for studying the evolution of complex parental care in a laboratory. Nicrophorus species depend on small vertebrate carcasses to breed, which they process and provision to their begging offspring. However, vertebrate carcasses are highly sought after by a wide variety of species and so competition is expected to be critical to the evolution of parental care. Despite this, the competitive environment for Nicrophorus is rarely characterized in the wild and remains a missing factor in laboratory studies. Here, we performed a systematic sampling of Nicrophorus orbicollis living near the southern extent of their range at Whitehall Forest in Clarke County, Georgia, USA. We determined the density of N. orbicollis and other necrophilous species that may affect the availability of this breeding resource through interference or exploitation competition. In addition, we characterize body size, a key trait involved in competitive ability, for all Nicrophorus species at Whitehall Forest throughout the season. Finally, we compare our findings to other published natural history data for Nicrophorines. We document a significantly longer active season than was observed twenty years previously at Whitehall Forest for both N. orbicollis and Nicrophorus tomentosus, potentially due to climate change. As expected, the adult body size of N. orbicollis was larger than N. tomentosus, the only other Nicrophorus species that was captured in 2022 at Whitehall Forest. The other most prevalent interspecific insects captured included species in the families Staphylinidae, Histeridae, Scarabaeidae, and Elateridae, which may act as competitors or predators of Nicrophorus eggs and larvae. Together, our results indicate significant variation in intra- and interspecific competition relative to populations within the N. orbicollis range. These findings suggest that the competitive environment varies extensively over space and time, which help to inform the role of ecology in the evolution of parental care in this species.

ecology↗

bioRxiv2022

Flexible parental care ensures robustness of post-embryonic development

The evolutionary repercussions of parental effects are often discussed as static effects that can have negative influences on offspring fitness that may even persist across generations. However, individuals are not passive recipients and may mitigate the persistence of parental effects through their behaviour. Here, we tested how the burying beetle Nicrophorus orbicollis, a species with complex parental care, responded to poor parenting. We manipulated the duration of parental care received and measured the impact on traits of both F1 and F2 offspring. As expected, reducing parental care negatively affected traits that are ecologically important for burying beetles, including F1 offspring development time and body size. However, F1 parents that received reduced care as larvae spent more time feeding F2 offspring than parents that received full care as larvae. As a result, both the number and mass of F2 offspring were unaffected by the developmental experience of their parents. Our results show that flexible parental care may be able to overcome poor developmental environments and limit negative parental effects to a single generation.

evolutionary biology↗

bioRxiv2022

Parallel evolution and cryptic diversification in the common and widespread Amazonian tree, Protium subserratum

The lowland Amazon rainforest houses some of the greatest tree diversity on earth. While the vast majority of these species are rare, a small number are common and widespread and thus considered to play a disproportionate role in many of the global ecosystem services provided by the Amazon. However, the extent to which dominant Amazonian tree species actually include multiple clades, each on their own unique evolutionary trajectory, is unknown. Here we investigate the extent to which lineage divergence may be occurring within Protium subserratum (Burseraceae), a common and widespread tree species that is monophyletic with populations exhibiting genotypic and phenotypic differences associated with soil and geography. Utilizing a combination of phylogenomic and population genomic methods with sampling from across the range, we found that P. subserratum contains at least eight distinct clades. Specialization onto white-sand soils has evolved independently at least two times within the species; however, phenotype is not correlated with soil type. Finally, cryptic diversity at the base of the Andes is associated with elevational shifts. Together these results lend support to the hypothesis that common and widespread Amazon tree species may not represent evolutionary cohesive units. Instead, these dominant species may more commonly represent species complexes, undergoing evolutionary transitions on a trajectory to become multiple range restricted, specialist species.

evolutionary biology↗

bioRxiv2022

Oxytocin/vasopressin system of insects influences parental care in males but not females

AO_SCPLOWBSTRACTC_SCPLOWParental care is thought to evolve through modification of behavioral precursors, which predicts that the mechanistic changes occur in the genes underlying those traits. The duplicated gene system of oxytocin/vasopressin has been broadly co-opted across vertebrates to influence parenting, from a pre-duplication ancestral role in water balance. It remains unclear whether co-option of these genes for parenting is limited to vertebrates. Here, we experimentally tested for associations between inotocin gene expression and water balance, parental acceptance of offspring, and active parenting in the subsocial beetle Nicrophorus orbicollis, to test whether a single copy homologue, inotocin, has similarly been co-opted for parental care in a species with elaborate parenting. As expected, inotocin was associated with water balance in both sexes. Inotocin expression increased around sexual maturation in both males and females, although more clearly in males. Finally, we found that expression of inotocin was not associated with acceptance of larvae but was associated with a transition to male but not female parenting. Moreover, level of offspring provisioning behavior and gene expression were positively correlated in males but uncorrelated in females. Our results suggest a broad co-option of this system for parenting that may have existed prior to gene duplication, and that inotocin may be associated with flexibility in parenting behavior. IO_SCPLOWMPACTC_SCPLOW SO_SCPLOWUMMARYC_SCPLOWOxytocin/vasopressin are amongst the most studied neuropeptides in vertebrates, influencing water balance, mating interactions, and most notably, social bonding. This gene pair evolved from a duplication in the vertebrate lineage of an ancestral vasopressin-like gene. Are the multiple social effects in vertebrates due to this duplication, or are social influences also ancestral? Here, we demonstrate that, in a biparental social beetle with a single copy, inotocin is associated with social interactions between fathers and offspring as well as being associated with the ancestral role of water balance in both males and females. In vertebrates, both oxytocin and vasopressin have been shown to impact social interactions in both sexes, although often showing sex-specificity in their action within species. Our results suggest that this system may have been co-opted for parenting prior to gene duplication and may facilitate flexibility in caring behavior.

evolutionary biology↗

bioRxiv2021

Patterns of parent and offspring gene expression reflect canalization, not plasticity, in response to environmental stress

Parenting is thought to evolve to buffer offspring from variable, unpredictable, and challenging environmental conditions. In the subsocial carrion beetle, Nicrophorus orbicollis, stressful temperatures during parenting do not affect parental behavior despite imposing steep fitness costs to parents. Here, we ask if plasticity of gene expression underpins this behavioral stability or facilitates independent compensation by larvae. To test this we characterized gene expression of parents and offspring before and during active parenting under benign (20{degrees}C) and stressful (24{degrees}C) temperatures to identify genes of parents and offspring associated with thermal response, parenting/being parented, and gene expression plasticity associated with behavioral stability of parental care. The main effects of thermal and social condition each shaped patterns of gene expression in females, males, and larvae. In addition, we implicated 79 genes in females as buffering parental behavior across environments. The majority of these underwent significant changes in expression in actively parenting mothers at the benign temperature, but not at the stressful temperature. Our results suggest that neither genetic programs for parenting nor their effects on offspring gene expression are fundamentally different under stressful conditions, and that behavioral stability is associated primarily with the maintenance of existing genetic programs rather than replacement or supplementation. Thus, while selection for compensatory gene expression could expand the range of thermal conditions parents will tolerate, without expanding the toolkit of genes involved selection is unlikely to lead to adaptive changes of function.

evolutionary biology↗

bioRxiv2021

Runaway evolution from male-male competition

Wondrously elaborate weapons and displays that appear to be counter to ecological optima are widespread features of male contests for mates across the animal kingdom. To understand how such diverse traits evolve, here we develop a quantitative genetic model of sexual selection for a male signaling trait that mediates aggression in male-male contests and show that an honest indicator of aggression can generate selection on itself by altering the social environment. This can cause selection to accelerate as the trait is elaborated, leading to runaway evolution. Thus, an evolving source of selection provided by the social environment is the fundamental unifying feature of runaway sexual selection driven by either male-male competition or female mate choice. However, a key difference is that runaway driven by male-male competition requires signal honesty. Our model identifies simple conditions that provide clear, testable predictions for empirical studies using standard quantitative genetic methods.

evolutionary biology↗

bioRxiv2021

Interacting Phenotypes and the Coevolutionary Process

Coevolution occurs when species interact to influence one anothers fitness, resulting in reciprocal evolutionary change. In many coevolving lineages, trait expression in one species is modified by the genotypes and phenotypes of the other, forming feedback loops reminiscent of models of intraspecific social evolution. Here, we adapt the theory of within-species social evolution, characterized by indirect genetic effects and social selection imposed by interacting individuals, to the case of interspecific interactions. In a trait-based model, we derive general expressions for multivariate evolutionary change in two species and the expected between-species covariance in evolutionary change when selection varies across space. We show that reciprocal interspecific indirect genetic effects can dominate the coevolutionary process and drive patterns of correlated evolution beyond what is expected from direct selection alone. In extreme cases, interspecific indirect genetic effects can lead to coevolution when selection does not covary between species or even when one species lacks genetic variance. Moreover, our model indicates that interspecific indirect genetic effects may interact in complex ways with cross-species selection to determine the course of coevolution. Importantly, our model makes empirically testable predictions for how different forms of reciprocal interactions contribute to the coevolutionary process.

evolutionary biology↗

bioRxiv2021

Constrained flexibility of parental cooperation limits evolutionary responses to harsh conditions

Parental care is predicted to evolve to mitigate harsh environments, thus adaptive plasticity of care may be an important response to climate change. In biparental species, fitness costs may be reduced with plasticity of behavior among partners. We investigated this prediction with the burying beetle, Nicrophorus orbicollis, by exposing them to contrasting benign and harsh thermal environments. We found strong fitness costs under the harsh environment, but rather than select for more care, visualized selection was stabilizing. Examining different components of care revealed positive directional selection gradients for direct care and strong stabilizing selection gradients for indirect care, resulting in constrained evolutionary responses. Further, because males and females did not coordinate their investments, the potential for adaptive plasticity was not enhanced under biparental care. Females cared at capacity with or without male partners, while males with partners reduced direct care but maintained indirect care levels. Decision rules were not altered in different environments, suggesting no shift from sexual conflict to cooperation. We suggest that the potential for parenting to ameliorate the effects of our climate crisis may depend on the sex-specific evolutionary drivers of parental care, and that this may be best reflected in components of care.

evolutionary biology↗

bioRxiv2021

A Synthesis of Game Theory and Quantitative Genetic Models of Social Evolution

Two popular approaches for modeling social evolution, evolutionary game theory and quantitative genetics, ask complementary questions but are rarely integrated. Game theory focuses on evolutionary outcomes, with models solving for evolutionarily stable equilibria, whereas quantitative genetics provides insight into evolutionary processes, with models predicting short-term responses to selection. Here we draw parallels between evolutionary game theory and interacting phenotypes theory, which is a quantitative genetic framework for understanding social evolution. First, we show how any evolutionary game may be translated into two quantitative genetic selection gradients, nonsocial and social selection, which may be used to predict evolutionary change from a single round of the game. We show that synergistic fitness effects may alter predicted selection gradients, causing changes in magnitude and sign as the population mean evolves. Second, we show how evolutionary games involving plastic behavioral responses to partners can be modeled using indirect genetic effects, which describe how trait expression changes in response to genes in the social environment. We demonstrate that repeated social interactions in models of reciprocity generate indirect effects and conversely, that estimates of parameters from indirect genetic effect models may be used to predict the evolution of reciprocity. We argue that a pluralistic view incorporating both theoretical approaches will benefit empiricists and theorists studying social evolution. We advocate the measurement of social selection and indirect genetic effects in natural populations to test the predictions from game theory, and in turn, the use of game theory models to aid in the interpretation of quantitative genetic estimates.

evolutionary biology↗

bioRxiv2019

More than DNA methylation: does pleiotropy drive the complex pattern of evolution of Dnmt1?

DNA methylation is an important chromatin modification that can stably alter gene expression in cells and maintain genome integrity in plants and vertebrates. The function of DNA methylation outside of these well-studied systems, however, is unclear. Insects, in particular, represent an understudied group. Variation in the level of DNA methylation and gains and losses in the maintenance methyltransferase, DNMT1, across the insect tree of life suggests that there is much we dont understand about DMNT1 function and evolution. One constant across the studies examining patterns of Dnmt1 expression in insects is that expression is consistently high in reproductive tissues compared to somatic tissue. The explanation for this has been that DNMT1 is required in tissues that have high levels of cell division. Our previous study found that downregulation of Dnmt1 expression in the milkweed bug Oncopeltus fasciatus results in the expected reduction of DNA methylation, no global changes in gene expression reflecting changes in DNA methylation, and the loss of the ability to produce viable oocytes. Here, we show that females treated with ds-Dnmt1 RNA during larval development have a more extreme phenotype; they lack oocytes entirely but develop a normal somatic ovary. Our results indicate a specific role for DNMT1 in the formation of gametes and are consistent with data from other systems, including Tribolium castaneum, a species does not have DNA methylation. We propose that DNMT1 has multiple functional roles in addition to methylating DNA, which explains its complex patterns of evolution, and suggests that previous inferences of causation from associations are premature.

evolutionary biology↗