Biology subjects

Lindsey, A. R. I.

Publications and source records attributed to Lindsey, A. R. I..

11 recordsLinked to original sources

bioRxiv2026

Asymmetry and niche partitioning shape the infection dynamics of co-transmitted Wolbachia symbionts

Wolbachia is an incredibly widespread maternally transmitted bacterium in arthropods that can alter host physiology, nutrition, reproduction, and immunity. In some cases, multiple Wolbachia strains infect the same host and are stably transmitted alongside each other. This raises the question of how multiple intracellular symbionts interact with each another and with the host to ensure stable transmission. Here, we use fluorescence in situ hybridizations and confocal microscopy to investigate co-transmission in a naturally occurring co-infection of two Wolbachia strains in Drosophila simulans: wHa and wNo. We find significant differences in spatial occupancy and abundance between the co-transmitted strains across stages of oogenesis and embryogenesis. We show that wHa and wNo have biases for different niches during oogenesis, and their strain-specific abundance is driven by egg chamber development, mating status, and their interaction. After differential curing of the co-infection, we find that wNo is dependent on wHa for vertical transmission, but not vice versa. Additionally, while wHa localization patterns are unchanged by loss of co-infection, abundance of wHa in the ovaries increases when wNo is removed. Understanding how symbiont co-infections achieve stability has important implications for the ongoing use of Wolbachia as a tool for insect management programs, but also for our understanding of the ecology of intracellular communities more broadly.

microbiology↗

bioRxiv2025

The genome of Istocheta aldrichi (Diptera: Tachinidae), a parasitoid of the Japanese beetle, Popillia japonica (Coleoptera: Scarabaeidae)

Istocheta aldrichi Mesnil 1953 (Diptera: Tachinidae), is native to Japan, and has recently become an important biological control agent of the Japanese beetle, Popillia japonica (Coleoptera: Scarabaeidae), a pest with >300 host plants, including roses, linden trees, and numerous agricultural crops. During the past decade, I. aldrichis range has greatly expanded across North America, particularly in Quebec and Ontario, Canada, and in the Midwest U.S. In many areas, including Minnesota, 15-60% of Japanese beetles are parasitized by I. aldrichi, highlighting its importance as a natural enemy. To facilitate research on I. aldrichi and other tachinid flies we present a reference genome generated from a single individual. The final genome assembly is 875.3 Mbp contained in 1,041 scaffolds, with an N50 of 4.77 Mbp, and 99.5% complete Diptera BUSCOs present. We also present a complete mitogenome and use comparative genomics across 19 tachinid species to identify unique features of I. aldrichi. Specifically, we find that while many tachinid lineages have experienced contractions in gene families, I. aldrichi is characterized by a relatively high number of gene family expansions, many of which are predicted to function in metal ion transport. Tachinids as a whole have undergone rapid copy number changes in 935 gene families, largely related to metabolism and morphogenesis. The I. aldrichi reference genome will further research opportunities on these parasitic flies, including their potential for biocontrol of P. japonica. ARTICLE SUMMARYThe parasitic fly Istocheta aldrichi attacks and kills the Japanese beetle (Popillia japonica), a pest of more than 300 plants. There is potential to leverage I. aldrichi for biological control of the beetle, but application is hindered by a limited understanding of this flys biology. This reference genome for I. aldrichi will enhance research future efforts and our ability to manage P. japonica.

genomics↗

bioRxiv2025

Wolbachia-mediated parthenogenesis induction in the aphid hyperparasitoid Alloxysta brevis (Hymenoptera: Figitidae: Charipinae)

Thelytokous parthenogenesis (thelytoky), in which females can produce female offspring without mating, can be caused by parthenogenesis-inducing endosymbiotic bacteria in the genus Wolbachia. This interaction is well known in hymenopteran parasitoids, where unfertilized eggs typically develop as males via haplo-diploidy in the absence of parthenogenesis-inducing bacteria. We report on a case of thelytoky in Alloxysta brevis (Thomson) (Hymenoptera: Figitidae), a globally widespread aphid hyperparasitoid. A previous study had shown that sex ratios of this species collected in Minnesota (USA) were extremely female biased, and we found here that unmated females reared from field-collected hosts produced female offspring without exposure to males. This result demonstrated thelytoky, and we tested for the role of bacterial endosymbionts by comparing offspring production of unmated females fed the antibiotic rifampicin to offspring production of control females not fed antibiotics. Antibiotic-fed females produced almost exclusively male offspring, and control females produced mainly females. This result showed that antibiotic treatment facilitated male production by unmated Alloxysta brevis females, thus implicating bacterial symbiosis in the expression of thelytoky. We then used molecular analyses to determine the identity of the symbiont. These analyses identified a Wolbachia strain from supergroup B, and excluded other bacteria known to mediate parthenogenesis induction, such as Cardinium and Rickettsia. While Wolbachia had been previously detected by molecular analysis in this species, these are the first experiments demonstrating Wolbachia-mediated parthenogenesis in the figitid subfamily Charipinae. IMPORTANCEParthenogenesis induction in insects can have important environmental and economic consequences. This is especially true if pests or their natural enemies are affected. The case of Alloxysta brevis is of particular interest, as this species is a hyperparasitoid of aphids, meaning that they attack and kill primary parasitoids of aphids. The populations of many species of pest aphids are controlled by primary parasitoid species, and hyperparasitoids thus have the potential to interfere with this mechanism of control. The role of hyperparasitoid parthenogenesis in the suppression of aphids by primary parasitoids remains unexplored. Thus, the results of this set of studies provides a starting point for determining whether parthenogenesis-inducing Wolbachia in hyperparasitoids should be expected to improve or hinder biological control of pest aphids by primary parasitoids. The focus on Alloxysta brevis as a model for these questions could be particularly instructive, since it is a species of worldwide distribution that is involved in numerous economically important aphid-parasitoid interactions.

microbiology↗

bioRxiv2024

A reference genome for Trichogramma kaykai: A tiny desert-dwelling parasitoid wasp with competing sex-ratio distorters

The tiny parasitoid wasp Trichogramma kaykai inhabits the Mojave Desert of the southwest United States. Populations of this tiny insect variably host up to two different sex-distorting genetic elements: (1) the endosymbiotic bacterium Wolbachia which induces the parthenogenetic reproduction of females, and (2) a B-chromosome, "Paternal Sex Ratio" (PSR), which converts would-be female offspring to PSR-transmitting males. We report here the genome of a Wolbachia-infected Trichogramma kaykai isofemale colony KSX58. Using Oxford Nanopore sequencing we produced a final genome assembly of 203 Mbp with 45x coverage, consisting of 213 contigs with an N50 of 1.9 Mbp. The assembly is quite complete, with 91.41% complete BUSCOs recovered: a very high score for Trichogrammatids that have been previously characterized for having high levels of core gene losses. We also report a complete mitochondrial genome for T. kaykai, and an assembly of the associated Wolbachia, strain wTkk. We identified copies of the parthenogenesis-inducing genes pifA and pifB in a remnant prophage region of the wTkk genome. The Trichogramma kaykai assembly is the highest quality genome assembly for the genus to-date and will serve as a great resource for understanding the evolution of sex and selfish genetic elements.

genomics↗

bioRxiv2023

Common Analysis of Direct RNA SequencinG CUrrently Leads to Misidentification of 5-Methylcytosine Modifications at GCU Motifs

RNA modifications, such as methylation, can be detected with Oxford Nanopore Technologies direct RNA sequencing. One commonly used tool for detecting 5-methylcytosine (m5C) modifications is Tombo, which uses an "Alternative Model" to detect putative modifications from a single sample. We examined direct RNA sequencing data from diverse taxa including virus, bacteria, fungi, and animals. The algorithm consistently identified a 5-methylcytosine at the central position of a GCU motif. However, it also identified a 5-methylcytosine in the same motif in fully unmodified in vitro transcribed RNA, suggesting that this a frequent false prediction. In the absence of further validation, several published predictions of 5-methylcytosine in human coronavirus and human cerebral organoid RNA in a GCU context should be reconsidered. IMPORTANCEThe detection of chemical modifications to RNA is a rapidly expanding field within epigenetics. Nanopore sequencing technology provides an attractive means of detecting these modifications directly on the RNA, but accurate modification predictions are dependent upon the software developed to interpret the sequencing results. One of these tools, Tombo, allows users to detect modifications using sequencing results from a single RNA sample. However, we find that this method falsely predicts modifications in a specific sequence context across a variety of RNA samples, including RNA that lacks modifications. Results from previous publications include predictions in human coronaviruses with this sequence context and should be reconsidered. Our results highlight the importance of using RNA modification detection tools with caution in the absence of a control RNA sample for comparison.

genomics↗

bioRxiv2023

The Genome of the Soybean Gall Midge (Resseliella maxima)

The cecidomyiid fly, soybean gall midge, Resseliella maxima Gagne, is a recently discovered insect that feeds on soybean plants in the Midwest US. Resseliella maxima larvae feed on soybean stems which may induce plant death and can cause considerable yield losses, making it an important agricultural pest. From three pools of 50 adults each, we used long-read nanopore sequencing to assemble a R. maxima reference genome. The final genome assembly is 206 Mb with 64.88X coverage, consisting of 1009 contigs with an N50 size of 714 kb. The assembly is high quality with a BUSCO score of 87.8%. Genome-wide GC level is 31.60% and DNA methylation was measured at 1.07%. The R. maxima genome is comprised of 21.73% repetitive DNA, which is in line with other cecidomyiids. Protein prediction annotated 14,798 coding genes with 89.9% protein BUSCO score. Mitogenome analysis indicated that R. maxima assembly is a single circular contig of 15,301 bp and shares highest identity to the mitogenome of the Asian rice gall midge, Orseolia oryzae (Wood-Mason). The R. maxima genome has one of the highest completeness levels for a cecidomyiid and will provide a resource for research focused on the biology, genetics, and evolution of cecidomyiids, as well as plant-insect interactions in this important agricultural pest.

genomics↗

bioRxiv2022

Infection dynamics of co-transmitted reproductive symbionts are mediated by sex, tissue, and development

One of the most prevalent intracellular infections on earth is with Wolbachia: a bacterium in the Rickettsiales that infects a range of insects, crustaceans, chelicerates, and nematodes. Wolbachia is maternally transmitted to offspring and has profound effects on the reproduction and physiology of its hosts, which can result in reproductive isolation, altered vectorial capacity, mitochondrial sweeps, and even host speciation. Some populations stably harbor multiple Wolbachia strains, which can further contribute to reproductive isolation and altered host physiology. However, almost nothing is known about the requirements for multiple intracellular microbes to be stably maintained across generations while they likely compete for space and resources. Here we use a coinfection of two Wolbachia strains ("wHa" and "wNo") in Drosophila simulans to define the infection and transmission dynamics of an evolutionarily stable double infection. We find that a combination of sex, tissue, and host development contribute to the infection dynamics of the two microbes and that these infections exhibit a degree of niche partitioning across host tissues. wHa is present at a significantly higher titer than wNo in most tissues and developmental stages, but wNo is uniquely dominant in ovaries. Unexpectedly, the ratio of wHa to wNo in embryos does not reflect those observed in the ovaries, indicative of strain-specific transmission dynamics. Understanding how Wolbachia strains interact to establish and maintain stable infections has important implications for the development and effective implementation of Wolbachia-based vector biocontrol strategies, as well as more broadly defining how cooperation and conflict shape intracellular communities. IMPORTANCEWolbachia are maternally transmitted intracellular bacteria that manipulate the reproduction and physiology of arthropods, resulting in drastic effects on the fitness, evolution, and even speciation of their hosts. Some hosts naturally harbor multiple strains of Wolbachia that are stably transmitted across generations, but almost nothing is known about the factors that limit or promote these co-infections which can have profound effects on the hosts biology and evolution, and are under consideration as an insect-management tool. Here we define the infection dynamics of a known stably transmitted double infection in Drosophila simulans with an eye towards understanding the patterns of infection that might facilitate compatibility between the two microbes. We find that a combination of sex, tissue, and development all contribute how the coinfection establishes.

microbiology↗

bioRxiv2021

DROP: Molecular voucher database for identification of Drosophila parasitoids

Molecular identification is increasingly used to speed up biodiversity surveys and laboratory experiments. However, many groups of organisms cannot be reliably identified using standard databases such as GenBank or BOLD due to lack of sequenced voucher specimens identified by experts. Sometimes a large number of sequences are available, but with too many errors to allow identification. Here we address this problem for parasitoids of Drosophila by introducing a curated open-access molecular reference database, DROP (Drosophila parasitoids). Identifying Drosophila parasitoids is challenging and poses a major impediment to realize the full potential of this model system in studies ranging from molecular mechanisms to food webs, and in biological control of Drosophila suzukii. In DROP (http://doi.org/10.5281/zenodo.4519656), genetic data are linked to voucher specimens and, where possible, the voucher specimens are identified by taxonomists and vetted through direct comparison with primary type material. To initiate DROP, we curated 154 laboratory strains, 856 vouchers, 554 DNA sequences, 16 genomes, 14 transcriptomes, and 6 proteomes drawn from a total of 183 operational taxonomic units (OTUs): 114 described Drosophila parasitoid species and 69 provisional species. We found species richness of Drosophila parasitoids to be heavily underestimated and provide an updated taxonomic catalogue for the community. DROP offers accurate molecular identification and improves cross-referencing between individual studies that we hope will catalyze research on this diverse and fascinating model system. Our effort should also serve as an example for researchers facing similar molecular identification problems in other groups of organisms.

genomics↗

bioRxiv2020

Wolbachia and virus alter the host transcriptome at the interface of nucleotide metabolism pathways

Wolbachia is a maternally transmitted bacterium that manipulates arthropod and nematode biology in myriad ways. The Wolbachia strain colonizing Drosophila melanogaster creates sperm-egg incompatibilities and protects its host against RNA viruses, making it a promising tool for vector control. Despite successful trials using Wolbachia-transfected mosquitoes for Dengue control, knowledge of how Wolbachia and viruses jointly affect insect biology remains limited. Using the Drosophila model, transcriptomics and gene expression network analyses revealed pathways with altered expression and splicing due to Wolbachia colonization and virus infection. Included are metabolic pathways previously unknown to be important for Wolbachia-host interactions. Additionally, Wolbachia-colonized flies exhibit a dampened transcriptomic response to virus infection, consistent with early blocking of virus replication. Finally, using Drosophila genetics, we show Wolbachia and expression of nucleotide metabolism genes have interactive effects on virus replication. Understanding the mechanisms of pathogen blocking will contribute to the effective development of Wolbachia-mediated vector control programs.

microbiology↗

bioRxiv2018

The Genomic Basis of Arthropod Diversity

BackgroundArthropods comprise the largest and most diverse phylum on Earth and play vital roles in nearly every ecosystem. Their diversity stems in part from variations on a conserved body plan, resulting from and recorded in adaptive changes in the genome. Dissection of the genomic record of sequence change enables broad questions regarding genome evolution to be addressed, even across hyper-diverse taxa within arthropods.\n\nResultsUsing 76 whole genome sequences representing 21 orders spanning more than 500 million years of arthropod evolution, we document changes in gene and protein domain content and provide temporal and phylogenetic context for interpreting these innovations. We identify many novel gene families that arose early in the evolution of arthropods and during the diversification of insects into modern orders. We reveal unexpected variation in patterns of DNA methylation across arthropods and examples of gene family and protein domain evolution coincident with the appearance of notable phenotypic and physiological adaptations such as flight, metamorphosis, sociality and chemoperception.\n\nConclusionsThese analyses demonstrate how large-scale comparative genomics can provide broad new insights into the genotype to phenotype map and generate testable hypotheses about the evolution of animal diversity.

genomics↗

bioRxiv2017

Evolutionary genetics of cytoplasmic incompatibility genes cifA and cifB in prophage WO of Wolbachia

The bacterial endosymbiont Wolbachia manipulates arthropod reproduction to facilitate its maternal spread through populations. The most common manipulation is cytoplasmic incompatibility (CI): Wolbachia-infected males produce modified sperm that cause embryonic mortality, unless rescued by eggs harboring the same Wolbachia. The genes underlying CI, cifA and cifB, were recently identified in the eukaryotic association module of Wolbachias prophage WO. Here, we use transcriptomic and genomic approaches to address three important evolutionary facets of these genes. First, we assess whether or not cifA and cifB comprise a classic toxin-antitoxin operon, and show they do not form an operon in strain wMel. They coevolve but exhibit strikingly distinct expression across host development. Second, we provide new domain and functional predictions across homologs within Wolbachia, and we show amino acid sequences vary substantially across the genus. Lastly, we investigate conservation of cifA and cifB and find degradation and loss of the genes is common in strains that no longer induce CI. Taken together, we find no evidence for the operon hypothesis in wMel, provide functional annotations that broaden the potential mechanisms of CI induction, illuminate recurrent erosion of cifA and cifB in non-CI strains, and advance an understanding of the most widespread form of reproductive parasitism.

evolutionary biology↗