Biology subjects

Metz, H. C.

Publications and source records attributed to Metz, H. C..

10 recordsLinked to original sources

bioRxiv2024

Expression of endogenous Anopheles gambiae microRNAs using an Anopheles gambiae densovirus (AgDNV) intronic expression system

Anopheles gambiae densovirus (AgDNV) is a highly species-specific parvovirus that reaches high titers in adult Anopheles gambiae mosquitoes with few transcriptomic effects and no significant fitness effects. Given these characteristics, AgDNV has been proposed as a viral vector for basic research and mosquito control. Previous work created an AgDNV co-expression system with a wild-type AgDNV helper plasmid and a transducing enhanced green fluorescent protein (EGFP) expressing plasmid that can be used to co-transfect cells to generate infectious recombinant transducing AgDNV virions. Generated virions infect the An. gambiae midgut, fat body, and ovaries, yet this viral vector system is limited in the size of transgenes that can be expressed due to capsid packaging limitations. Considering these size constraints, we created an artificial intron within the EGFP gene of the transducing construct that can express small pieces of genetic material such as microRNAs (miRNAs), microRNA sponges, or other small sequences. Placement of this intron in EGFP created a fluorescent reporter such that incorrect splicing produces a frameshift mutation in EGFP and an early stop codon whereas correct splicing results in normal EGFP expression and co-transcription of the intronic genetic cargo. A selection of miRNAs with predicted or demonstrated importance in mosquito immunity and reproduction with expression localized to the fat body or ovaries were chosen as intronic cargo, construct expression and splicing evaluated, and the impact of miRNA expression on putative miRNA targets was measured in vitro and in vivo. While the intron was correctly spliced in cells and mosquitoes, miRNA delivery resulted in inconsistent changes to miRNA and target gene transcript levels--possibly due to organ-specific miRNA expression or miRNA-target gene sequence mismatch. However, with optimization this viral vector and developed intron have potential as an expression tool within An. gambiae mosquitoes or cells.

microbiology↗

bioRxiv2024

Olfactory receptor coexpression and co-option in the dengue mosquito

The olfactory sensory neurons of vinegar flies and mice tend to express a single ligand-specific receptor. While this one neuron-one receptor motif has long been expected to apply broadly across insects, recent evidence suggests it may not extend to mosquitoes. We sequenced and analyzed the transcriptomes of 46,000 neurons from antennae of the dengue mosquito Aedes aegypti to resolve all olfactory, thermosensory, and hygrosensory neuron subtypes and identify the receptors expressed therein. We find that half of all olfactory subtypes coexpress multiple receptors. However, coexpression occurs almost exclusively among genes from the same family--among odorant receptors (ORs) or among ionotropic receptors (IRs). Coexpression of ORs with IRs is exceedingly rare. Many coexpressed receptors are recent duplicates. In other cases, the recruitment or co-option of single receptors by multiple neuron subtypes has placed these genes together in the same cells with distant paralogs. Close examination of data from Drosophila reveal rare cases of both phenomena, indicating that the olfactory systems of these two species are not fundamentally different, but instead fall at different locations along a continuum likely to encompass diverse insects.

neuroscience↗

bioRxiv2023

In Silico Characterization of Intracellular Localization Signals and Structural Features of Mosquito Densovirus (MDV) Viral Proteins

As entomopathogenic viruses, mosquito densoviruses (MDVs) are widely studied for their potential as biocontrol agents and molecular laboratory tools for mosquito manipulation. The nucleus of the mosquito cell is the site for MDV genome replication and capsid assembly, however the nuclear localization signals (NLSs) and nuclear export signals (NES) for MDV proteins have not yet been identified. We carried out an in silico analysis to identify putative NLSs and NESs in the viral proteins of densoviruses that infect diverse mosquito genera (Aedes, Anopheles, and Culex) and identified putative phosphorylation and glycosylation sites on these proteins. These analyses lead to a more comprehensive understanding of how MDVs are transported into and out of the nucleus and lay the foundation for the potential use of densoviruses in mosquito control and basic research. Data summaryData used in this article were obtained from the GenBank database using accession numbers AYH52680, AYH52678, AYH52679, ABX83665, ABX83663, ABX83664, ABU95013, ABU95011, ABU95012, and AXQ04861. Impact statementMosquito densoviruses (MDVs) are of interest as mosquito biocontrol agents and as laboratory research tools. The trafficking of viral proteins to the cell nucleus is a critical step in viral replication. We used in silico approaches to identify putative nuclear localization signals and nuclear export signals for MDVs that infect the three major genera of pathogen-transmitting mosquitoes (Aedes, Anopheles, and Culex). These analyses lead a more comprehensive understanding of how MDVs are transported into and out of the nucleus and lay the foundation for the potential use of densoviruses in mosquito control and basic research.

microbiology↗

bioRxiv2023

A single genetic locus lengthens deer mouse burrows via motor pattern evolution

The question of how evolution builds complex behaviors has long fascinated biologists. To address this question from a genetic perspective, we capitalize on variation in innate burrowing behavior between two sister species of Peromyscus mice: P. maniculatus that construct short, simple burrows and P. polionotus that uniquely construct long, elaborate burrows. We identify three regions of the genome associated with differences in burrow length and then narrow in on one large-effect 12-Mb locus on chromosome 4. By introgressing the P. polionotus allele into a P. maniculatus background, we demonstrate this locus, on its own, increases burrow length by 20%. Next, by recording mice digging in a transparent tube, we find this locus has specific effects on burrowing behavior. This locus does not affect time spent digging or latency to dig, but rather affects usage of only two of the primary digging behaviors that differ between the focal species: forelimb digging, which loosens substrate, and hindlimb kicking, which powerfully ejects substrate. This locus has an especially large effect on hindkicking, explaining 56% and 22% of interspecific differences in latency and proportion of hindkicks, respectively. Together, these data provide genetic support for the hierarchical organization of complex behaviors, offering evolution the opportunity to tinker with specific behavioral components.

evolutionary biology↗

bioRxiv2023

Variable effects of Wolbachia on alphavirus infection in Aedes aegypti

2.Wolbachia pipientis (=Wolbachia) has promise as a tool to suppress virus transmission by Aedes aegypti mosquitoes. However, Wolbachia can have variable effects on mosquito-borne viruses. This variation remains poorly characterized, yet the multimodal effects of Wolbachia on diverse pathogens could have important implications for public health. Here, we examine the effects of somatic infection with two strains of Wolbachia (wAlbB and wMel) on the alphaviruses Sindbis virus (SINV), Onyong-nyong virus (ONNV), and Mayaro virus (MAYV) in Ae. aegypti. We found variable effects of Wolbachia including enhancement and suppression of viral infections, with some effects depending on Wolbachia strain. Both wAlbB- and wMel-infected mosquitoes showed enhancement of SINV infection rates one week post-infection, with wAlbB-infected mosquitoes also having higher viral titers than controls. Infection rates with ONNV were low across all treatments and no significant effects of Wolbachia were observed. The effects of Wolbachia on MAYV infections were strikingly strain-specific; wMel strongly blocked MAYV infections and suppressed viral titers, while wAlbB did not influence MAYV infection. The variable effects of Wolbachia on vector competence underscore the importance of further research into how this bacterium impacts the virome of wild mosquitoes including the emergent human pathogens they transmit. Impact statementIn recent years, wild populations of Aedes aegypti mosquitoes have been deliberately infected with Wolbachia--a bacterium that helps to curb the spread of some pathogens including dengue virus. But how does Wolbachia affect the ability of mosquitoes to become infected with and spread the many different viruses they encounter in nature? Here, we characterize the effects of Wolbachia on three alphaviruses that cause illness in humans-- Sindbis virus, Onyong-nyong virus, and Mayaro virus. We find Wolbachia has variable effects on these pathogens, including significant enhancement of Sindbis virus infections. Our research has important implications for the design of vector control strategies, and suggests further research is needed to understand how Wolbachia shapes the replication and transmission of diverse viruses. 3. Data SummaryAll data in the study are available in the Figures and supplementary material.

microbiology↗

bioRxiv2022

Culex tarsalis is a competent host of the insect-specific alphavirus Eilat virus (EILV)

Eilat virus (EILV) is an insect-specific alphavirus that has the potential to be developed into a tool to combat mosquito-borne pathogens. However, its mosquito host range and transmission routes are not well understood. Here we fill this gap by investigating EILVs host competence and tissue tropism in five mosquito species: Aedes aegypti, Culex tarsalis, Anopheles gambiae, Anopheles stephensi, and Anopheles albimanus. Of the tested species, Cx. tarsalis was the most competent host for EILV. The virus was found in Cx. tarsalis ovaries, but no vertical or venereal transmission was observed. Culex tarsalis also transmitted EILV via saliva, suggesting the potential for horizontal transmission between an unknown vertebrate or invertebrate host. We found that reptile (turtle and snake) cells lines were not competent for EILV infection. We tested a potential invertebrate host (Manduca sexta caterpillars) but found they were not susceptible to EILV infection. Together, our results suggest that EILV could be developed as a tool to target pathogenic viruses that use Culex tarsalis as a vector. Our work sheds light on the infection and transmission dynamics of a poorly understood insect-specific virus and reveals it may infect a broader range of mosquito species than previously recognized. IMPORTANCEThe recent discovery of insect-specific alphaviruses presents opportunities both to study the biology of virus host range and to develop them into tools against pathogenic arboviruses. Here we characterize the host range and transmission of Eilat virus in five mosquito species. We find that Culex tarsalis--a vector of harmful human pathogens including West Nile Virus--is a competent host of Eilat virus. However, how this virus is transmitted between mosquitoes remains unclear. We find that Eilat virus infects the tissues necessary for both vertical and horizontal transmission--a crucial step in discerning how Eilat virus maintains itself in nature.

microbiology↗

bioRxiv2022

Function and evolution of aquaporin IsAQP1 in the Lyme disease vector Ixodes scapularis

Ticks are important vectors of pathogenic viruses, bacteria, and protozoans to humans, wildlife, and domestic animals. Due to their life cycle, ticks face significant challenges related to water homeostasis. When blood-feeding they must excrete water and ions, but when off-host (for stretches lasting several months) they must conserve water to avoid desiccation. Aquaporins (AQPs), a family of membrane-bound water channels, are key players in osmoregulation in many animals but remain poorly characterized in ticks. Here, we bioinformatically identified AQP-like genes from the deer tick Ixodes scapularis and used phylogenetic approaches to map the evolution of the aquaporin gene family in arthropods. We find that most arachnid AQP-like sequences (including those of I. scapularis) form a monophyletic group clustered within aquaglycerolporins (GLPs) from bacteria to vertebrates. This gene family is absent from insects, revealing divergent evolutionary paths for AQPs in different hematophagous arthropods. We next sequenced the full-length cDNA of I. scapularis aquaporin 1 (IsAQP1) and expressed it heterologously in Xenopus oocytes to functionally characterize its permeability to water and solutes. We additionally examined IsAQP1 expression across different life stages and adult female tissues. We found IsAQP1 to be an efficient water channel with salivary gland-specific expression, implying its function may be closely tied to osmoregulation during blood-feeding. Its functional properties were unique: unlike most GLPs, IsAQP1 has low glycerol permeability, and unlike most AQPs, it is insensitive to mercury. Together, our results suggest IsAQP1 plays an important role in tick water balance during blood feeding and may hold promise as a target for novel vector control efforts. Graphical TOC/Abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY eTOCIsAQP1, an aquaporin found in the black legged tick (Ixodes scapularis), is a functional water channel with low permeability to glycerol. In a phylogenetic analysis of 176 sequences from 48 arachnid species, most tick and other arachnid AQP-like genes formed a monophyletic clade nested within aquaglyceroporins (GLPs). IsAQP1 shows salivary-gland specific expression in adult females--with highest expression in unfed females--suggesting a role in water balance during blood feeding.

genetics↗

bioRxiv2022

Anopheles albimanus is a potential alphavirus vector in the Americas

Despite its ecological flexibility and geographical co-occurrence with human pathogens, little is known about the ability for Anopheles albimanus to transmit arboviruses. To address this gap, we challenged An. albimanus females with four alphaviruses and one flavivirus and monitored progression of infections. We found this species is an efficient vector of the alphaviruses Mayaro virus, Onyong-nyong virus, and Sindbis virus, though the latter two do not currently exist in its habitat range. An. albimanus was able to become infected with Chikungunya virus, but virus dissemination was rare (indicating the presence of a midgut escape barrier), and no mosquito transmitted. Mayaro virus rapidly established disseminated infections in An. albimanus females and was detected in the saliva of a substantial proportion of infected mosquitoes. Consistent with previous work in other anophelines, we find that An. albimanus is refractory to infection with flaviviruses, a phenotype that did not depend on midgut-specific barriers. Our work demonstrates that An. albimanus may be a vector of neglected emerging human pathogens and adds to recent evidence that anophelines are competent vectors for diverse arboviruses.

microbiology↗

bioRxiv2022

Sexual transmission of Anopheles gambiae densovirus (AgDNV) leads to disseminated infection in mated females

BackgroundAnopheles gambiae densovirus (AgDNV) is an insect-specific, single-stranded DNA virus that infects An. gambiae, the major mosquito species responsible for transmitting malaria parasites throughout Sub-Saharan Africa. AgDNV is a benign virus that is very specific to its mosquito host and therefore has potential to serve as a vector control tool via paratransgenesis (genetic modification of mosquito symbionts) to limit transmission of human pathogens. Prior to being engineered into a control tool, the natural transmission dynamics of AgDNV between An. gambiae mosquitoes needs to be fully understood. Additionally, improved knowledge of AgDNV infection in male mosquitoes is needed. In this study, we examine the tissue tropism of AgDNV in the male reproductive tract and investigate both venereal and vertical transmission dynamics of the virus. MethodsAn. gambiae adult males were infected with AgDNV via micro-injection and reproductive tissues collected and assayed for AgDNV using qPCR. Next, uninfected females were introduced to AgDNV-infected or control males and, after several nights of mating, both the spermatheca and female carcass were assessed for venereally transmitted AgDNV. Finally, F1s from this cross were collected and assayed to quantify vertical transmission of the virus. ResultsAgDNV infected the reproductive tract of male mosquitoes, including the testes and male accessory glands (MAGs), without affecting mating rates. AgDNV-infected males venereally transmitted virus to females, and these venereally-infected females developed disseminated infection throughout the body. However, AgDNV was not vertically transmitted to F1s resulting from this cross. ConclusionsInfected male releases could be an effective strategy to introduce AgDNV-based paratransgenic tools into naive populations of An. gambiae females.

microbiology↗

bioRxiv2017

Evolution and genetics of precocious burrowing behavior in Peromyscus mice

A central challenge in biology is to understand how innate behaviors evolve between closely related species. One way to elucidate how differences arise is to compare the development of behavior in species with distinct adult traits. Here, we report that Peromyscus polionotus is strikingly precocious with regard to burrowing behavior, but not other behaviors, compared to its sister species P. maniculatus. In P. polionotus, burrows were excavated as early as 17 days of age, while P. maniculatus did not build burrows until 10 days later. Moreover, the well-known differences in burrow architecture between adults of these species--P. polionotus adults excavate long burrows with an escape tunnel, while P. maniculatus dig short, single-tunnel burrows--were intact in juvenile burrowers. To test whether this juvenile behavior is influenced by early-life environment, pups of both species were reciprocally cross-fostered. Fostering did not alter the characteristic burrowing behavior of either species, suggesting these differences are genetic. In backcross F2 hybrids, we show that precocious burrowing and adult tunnel length are genetically correlated, and that a single P. polionotus allele in a genomic region linked to adult tunnel length is predictive of precocious burrow construction. The co-inheritance of developmental and adult traits indicates the same genetic region--either a single gene with pleiotropic effects, or closely linked genes-- acts on distinct aspects of the same behavior across life stages. Such genetic variants likely affect behavioral drive (i.e. motivation) to burrow, and thereby affect both the development and adult expression of burrowing behavior.\n\nHighlightsO_LIJuvenile P. polionotus construct burrows precociously compared to its sister species P. maniculatus\nC_LIO_LICross-fostering does not alter species-specific burrowing behavior\nC_LIO_LIA QTL linked to adult tunnel length predicts developmental onset of burrow construction in hybrids\nC_LIO_LIPleiotropic genetic variant(s) may affect behavioral drive across life stages\nC_LI

animal behavior and cognition↗