Scholarly Literature

This is a database of scholarly literature that concentrates currently on natural and engineered selfish genetic elements (gene drives).  The latest are shown here.
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Unravelling transmission ratio distortion across the bovine genome: identification of candidate regions for reproduction defects

26542
S. Id-Lahoucine, J. Casellas, A. Suárez-Vega, P. A. S. Fonseca, F. S. Schenkel, M. Sargolzaei and A. Cánovas,  BMC Genomics,  24:383. 2023-07-08 08:21:35.
Our results revealed the importance of implementing different TRD parameterizations to capture all types of distortions and to determine the corresponding inheritance pattern. Novel candidate genomic regions containing lethal alleles and genes with functional and biological consequences on fertility and pre‑ and post‑natal viability were also identified, providing opportunities for improving breeding success in cattle

Routes of Introduction of Anopheles gambiae Into Remote Islands in the Indian Ocean

26612
R. E. Ditter, M. Campos, M. W. Crepeau, J. Pinto, A. Toilibou, Y. Amina, Y. Lee, A. J. Cornel and G. C. Lanzaro,  2023-07-07 13:23:28.
The malaria vector Anopheles gambiae s.s., is a primary malaria vector throughout sub-Saharan Africa including the islands of the Comoros archipelago (Anjouan, Grande Comore, Mayotte and Mohéli). These islands are located at the northern end of the Mozambique Channel in eastern Africa. Previous studies have shown a relatively high degree of genetic isolation between island and mainland populations of A. gambiae, but the origin of the island populations remains unclear. Here, we analyzed phylogenetic relationships among island and mainland populations using complete mitochondrial genome sequences of individual A. gambiae specimens. We investigated the source population of A. gambiaefor each island, determined the number of introductions and estimated when they occurred, and explored evidence for contemporary gene flow between island and mainland populations. Phylogenetic analysis and haplotype networks were constructed from mitogenome sequences of 258 A. gambiae from the four islands. In addition, 112 individuals from seven countries across sub-Saharan Africa and Madagascar were included to identify potential source populations. Our results suggest that introduction events of A. gambiae into the Comoros archipelago were rare and recent events and that there is no evidence of contemporary migration between the islands and mainland Africa. This study further supports the suitability of these oceanic islands as appropriate sites for conducting field trial releases of genetically engineered mosquitoes (GEMs).

Threshold dynamics of a stochastic mathematical model for Wolbachia infections

26546
J. Yang, Z. Chen, Y. Tan, Z. Liu and R. A. Cheke,  Journal of Biological Dynamics,  17:2231967. 2023-07-07 08:51:13.
A stochastic mathematical model is proposed to study how environmental heterogeneity and the augmentation of mosquitoes with Wolbachia bacteria affect the outcomes of dengue disease. The existence and uniqueness of the positive solutions of the system are studied. Then the V-geometrically ergodicity and stochastic ultimate boundedness are investigated. Further, threshold conditions for successful population replacement are derived and the existence of a unique ergodic steady-state distribution of the system is explored. The results show that the ratio of infected to uninfected mosquitoes has a great influence on population replacement. Moreover, environmental noise plays a significant role in control of dengue fever.

The Effect of X-ray Irradiation on the Fitness and Field Adaptability of the Codling Moth: An Orchard Study in Northeast China

26544
J. Zhang, S. Huang, S. Zhao, X. Wang, X. Yang, H. Zhao, P. Gao, Y. Li and X. Yang,  Insects,  14. 2023-07-07 08:43:03.
The codling moth, Cydia pomonella (L.), is an invasive agricultural pest of pome fruits and walnuts in China that threatens the apple industry in the Loess Plateau and Bohai Bay; it has developed resistance to many insecticides. Sterile insect technique (SIT) combined with area-wide integrated pest management (AW-IPM) can reduce the risk of resistance to insecticides and effectively control some insect pest species. Our previous laboratory experiment found that irradiation with 366 Gy of X-ray caused the males of the codling moth to become sterile. However, the sterility and adaptability of males after being irradiated with 366 Gy X-ray in the field are still unclear. In this study, we investigated the effect of X-ray irradiation on the fitness of male adults that emerged from pupae irradiated with 366 Gy to explore their adaptability and mating competitiveness, and to examine the effect of releasing sterile male insects in orchards in northeast China on the fruit infestation rate of the Nanguo pear. The results showed that 366 Gy of X-ray irradiation significantly reduced the mating competitiveness of males and the hatching rate of the eggs laid by females pairing with sterile males. Meanwhile, the lifespan of the sterile male moths was significantly shorter than that of the normal ones in the field. A pilot test showed that the release twice of sterile male moths in the orchards had no significant effect on the fruit infestation rate. Our field experiments provide a scientific basis for the further optimization of the SIT technology program for controlling C. pomonella.

The evolutionary history of Drosophila simulans Y chromosomes reveals molecular signatures of resistance to sex ratio meiotic drive

26469
C. Courret, D. Ogereau, C. Gilbert, A. M. Larracuente and C. Montchamp-Moreau,  Mol Biol Evol,  2023-07-04 07:54:47.
The recent evolutionary history of the Y chromosome in Drosophila simulans, a worldwide species of Afrotropical origin, is closely linked to that of X-linked meiotic drivers (Paris system). The spread of the Paris drivers in natural populations has elicited the selection of drive resistant Y chromosomes. To infer the evolutionary history of the Y chromosome in relation to the Paris drive, we sequenced 21 iso-Y lines, each carrying a Y chromosome from a different location. Among them, 13 lines carry a Y chromosome that is able to counteract the effect of the drivers. Despite their very different geographical origins, all sensitive Y's are highly similar, suggesting that they share a recent common ancestor. The resistant Y chromosomes are more divergent and segregate in four distinct clusters. The phylogeny of the Y chromosome confirms that the resistant lineage predates the emergence of Paris drive. The ancestry of the resistant lineage is further supported by the examination of Y-linked sequences in the sister species of D. simulans, D. sechellia, and D. mauritiana. We also characterized the variation in repeat content among Y chromosomes and identified multiple simple satellites associated with resistance. Altogether, the molecular polymorphism allows us to infer the demographic and evolutionary history of the Y chromosome and provides new insights on the genetic basis of resistance.

Meiotic drive of noncentromeric loci in mammalian meiosis II eggs

26477
D. M. Silva and T. Akera,  Curr Opin Genet Dev,  81:102082. 2023-07-03 08:21:48.
The germline produces haploid gametes through a specialized cell division called meiosis. In general, homologous chromosomes from each parent segregate randomly to the daughter cells during meiosis, providing parental alleles with an equal chance of transmission. Meiotic drivers are selfish elements who cheat this process to increase their transmission rate. In female meiosis, selfish centromeres and noncentromeric drivers cheat by preferentially segregating to the egg cell. Selfish centromeres cheat in meiosis I (MI), while noncentromeric drivers can cheat in both meiosis I and meiosis II (MII). Here, we highlight recent advances on our understanding of the molecular mechanisms underlying these genetic cheating strategies, especially focusing on mammalian systems, and discuss new models of how noncentromeric selfish drivers can cheat in MII eggs.

Steering and controlling evolution — from bioengineering to fighting pathogens

26463
M. Lässig, V. Mustonen and A. Nourmohammad,  Nature Reviews Genetics,  2023-07-03 07:31:07.
Control interventions steer the evolution of molecules, viruses, microorganisms or other cells towards a desired outcome. Applications range from engineering biomolecules and synthetic organisms to drug, therapy and vaccine design against pathogens and cancer. In all these instances, a control system alters the eco-evolutionary trajectory of a target system, inducing new functions or suppressing escape evolution. Here, we synthesize the objectives, mechanisms and dynamics of eco-evolutionary control in different biological systems. We discuss how the control system learns and processes information about the target system by sensing or measuring, through adaptive evolution or computational prediction of future trajectories. This information flow distinguishes pre-emptive control strategies by humans from feedback control in biotic systems. We establish a cost–benefit calculus to gauge and optimize control protocols, highlighting the fundamental link between predictability of evolution and efficacy of pre-emptive control.

Novel Conservation Strategies to Conserve Australian Marsupials

28144
S. Legge, M. Hayward and A. Weeks,  American and Australasian Marsupials,  2023-07-01 10:36:55.
The Australian marsupial fauna has been devastated in the past 250 years, mainly due to impacts from invasive mammalian predators (cats and foxes), although other threats such as invasive herbivores, habitat loss and fragmentation, changes to fire regimes, and now climate change have played a role. The profound and ongoing impact of invasive predators has driven substantial research and management innovation. Australia has been at the forefront of developing approaches to reduce the density and impacts of introduced predators and implementing novel and ambitious species conservation programs. A large and growing network of islands and mainland fenced areas, free of introduced predators (“havens”), has been critical for avoiding further species extinctions. Outside these havens, advances in toxin presentation and deployment have enabled cat and fox densities to be reduced over large areas. Substantial research and field trials have been carried out to understand how predator-prey interactions, and habitat quality management, can be used to reduce predation impacts on susceptible native species. Synthetic biology offers new opportunities to manage introduced predators, including potentially by using gene drives. Finally, the attenuation of the formerly large continuous ranges of many species to small, isolated population remnants (because of predation or other reasons) has also driven research and improvements in genetic and metapopulation management that will increase the chance of population persistence in the longer term. However, unless Australia continues to invest in research and innovative conservation actions, the plight of its priceless marsupial fauna will remain perilous.

Wolbachia -mediated resistance to Zika virus infection in Aedes aegypti is dominated by diverse transcriptional regulation and weak evolutionary pressures

26604
E. C. Boehm, A. S. Jaeger, H. J. Ries, D. Castañeda, A. M. Weiler, C. C. Valencia, J. Weger-Lucarelli, G. D. Ebel, S. L. O'Connor, T. C. Friedrich, M. Zamanian and M. T. Aliota,  bioRxiv,  2023-06-26 13:09:35.
A promising candidate for arbovirus control and prevention relies on replacing arbovirus-susceptible Aedes aegypti populations with mosquitoes that have been colonized by the intracellular bacterium Wolbachia and thus have a reduced capacity to transmit arboviruses. This reduced capacity to transmit arboviruses is mediated through a phenomenon referred to as pathogen blocking. Pathogen blocking has primarily been proposed as a tool to control dengue virus (DENV) transmission, however it works against a range of viruses, including Zika virus (ZIKV). Despite years of research, the molecular mechanisms underlying pathogen blocking still need to be better understood. Here, we used RNA-seq to characterize mosquito gene transcription dynamics in Ae. aegypti infected with the w Mel strain of Wolbachia that are being released by the World Mosquito Program in Medellín, Colombia. Comparative analyses using ZIKV-infected, uninfected tissues, and mosquitoes without Wolbachia revealed that the influence of w Mel on mosquito gene transcription is multifactorial. Importantly, because Wolbachia limits, but does not completely prevent, replication of ZIKV and other viruses in coinfected mosquitoes, there is a possibility that these viruses could evolve resistance to pathogen blocking. Therefore, to understand the influence of Wolbachia on within-host ZIKV evolution, we characterized the genetic diversity of molecularly barcoded ZIKV virus populations replicating in Wolbachia -infected mosquitoes and found that within-host ZIKV evolution was subject to weak purifying selection and, unexpectedly, loose anatomical bottlenecks in the presence and absence of Wolbachia . Together, these findings suggest that there is no clear transcriptional profile associated with Wolbachia -mediated ZIKV restriction, and that there is no evidence for ZIKV escape from this restriction in our system. AUTHOR SUMMARY: When Wolbachia bacteria infect Aedes aegypti mosquitoes, they dramatically reduce the mosquitoes' susceptibility to infection with a range of arthropod-borne viruses, including Zika virus (ZIKV). Although this pathogen-blocking effect has been widely recognized, its mechanisms remain unclear. Furthermore, because Wolbachia limits, but does not completely prevent, replication of ZIKV and other viruses in coinfected mosquitoes, there is a possibility that these viruses could evolve resistance to Wolbachia -mediated blocking. Here, we use host transcriptomics and viral genome sequencing to examine the mechanisms of ZIKV pathogen blocking by Wolbachia and viral evolutionary dynamics in Ae. aegypti mosquitoes. We find complex transcriptome patterns that do not suggest a single clear mechanism for pathogen blocking. We also find no evidence that Wolbachia exerts detectable selective pressures on ZIKV in coinfected mosquitoes. Together our data suggest that it may be difficult for ZIKV to evolve Wolbachia resistance, perhaps due to the complexity of the pathogen blockade mechanism.

Impacts of sex ratio meiotic drive on genome structure and function in a stalk-eyed fly

26279
J. A. Reinhardt, R. H. Baker, A. V. Zimin, C. Ladias, K. A. Paczolt, J. H. Werren, C. Y. Hayashi and G. S. Wilkinson,  Genome Biology Evolution,  2023-06-26 10:49:44.
Stalk-eyed flies in the genus Teleopsis carry selfish genetic elements that induce sex ratio meiotic drive (SR) and impact the fitness of male and female carriers. Here, we assemble and describe a chromosome-level genome assembly of the stalk-eyed fly, Teleopsis dalmanni, to elucidate patterns of divergence associated with SR. The genome contains tens of thousands of transposable element (TE) insertions and hundreds of transcriptionally and insertionally active TE families. By resequencing pools of SR and ST males using short and long-reads, we find widespread differentiation and divergence between XSR and XST associated with multiple nested inversions involving most of the sex ratio haplotype. Examination of genomic coverage and gene expression data revealed seven X-linked genes with elevated expression and coverage in SR males. The most extreme and likely drive candidate involves an XSR-specific expansion of an array of partial copies of JASPer, a gene necessary for maintenance of euchromatin and associated with regulation of TE expression. In addition, we find evidence for rapid protein evolution between XSR and XST for testis expressed and novel genes, i.e. either recent duplicates or lacking a dipteran ortholog, including an X-linked duplicate of maelstrom, which is also involved in TE silencing. Overall, the evidence suggests that this ancient XSR polymorphism has had a variety of impacts on repetitive DNA and its regulation in this species.

MGSurvE: A framework to optimize trap placement for genetic surveillance of mosquito population

26616
C. H. Sánchez, D. L. Smith and J. M. Marshall,  bioRxiv,  2023-06-23 13:35:51.
Genetic surveillance of mosquito populations is becoming increasingly relevant as genetics-based mosquito control strategies advance from laboratory to field testing. Especially applicable are mosquito gene drive projects, the potential scale of which leads monitoring to be a significant cost driver. For these projects, monitoring will be required to detect unintended spread of gene drive mosquitoes beyond field sites, and the emergence of alternative alleles, such as drive-resistant alleles or non-functional effector genes, within intervention sites. This entails the need to distribute mosquito traps efficiently such that an allele of interest is detected as quickly as possible - ideally when remediation is still viable. Additionally, insecticide-based tools such as bednets are compromised by insecticide-resistance alleles for which there is also a need to detect as quickly as possible. To this end, we present MGSurvE (Mosquito Gene SurveillancE): a computational framework that optimizes trap placement for genetic surveillance of mosquito populations such that the time to detection of an allele of interest is minimized. A key strength of MGSurvE is that it allows important biological features of mosquitoes and the landscapes they inhabit to be accounted for, namely: i) resources required by mosquitoes (e.g., food sources and aquatic breeding sites) can be explicitly distributed through a landscape, ii) movement of mosquitoes may depend on their sex, the current state of their gonotrophic cycle (if female) and resource attractiveness, and iii) traps may differ in their attractiveness profile. Example MGSurvE analyses are presented to demonstrate optimal trap placement for: i) an Aedes aegypti population in a suburban landscape in Queensland, Australia, and ii)an Anopheles gambiae population on the island of São Tomé, São Tomé and Príncipe. Further documentation and use examples are provided in project's documentation. MGSurvE is freely available as an open-source Python package on pypi ( https://pypi.org/project/MGSurvE/ ). It is intended as a resource for both field and computational researchers interested in mosquito gene surveillance. AUTHOR SUMMARY: Mosquito-borne diseases such as malaria and dengue fever continue to pose a major health burden throughout much of the world. The impact of currently-available tools, such as insecticides and antimalarial drugs, is stagnating, and gene drive-modified mosquitoes are considered a novel tool that could contribute to continuing reductions in disease transmission. Gene drive approaches are unique in the field of vector control in that they involve transgenes that could potentially spread on a wide scale, and consequently, surveillance is expected to be a major cost driver for the technology. This is needed to monitor for unintended spread of intact drive alleles, and the emergence of alternative alleles such as homing-resistance alleles and non-functional effector genes. Additionally, surveillance of insecticide-resistance alleles is of interest to support the impact of insecticide-based tools such as bednets. Here, we present MGSurvE, a computational framework that optimizes trap placement for genetic surveillance of mosquito populations in order to minimize the time to detection for an allele of interest. MGSurvE has been tailored to various features of mosquito ecology, and is intended as a resource for researchers to optimize the efficiency of limited surveillance resources.

Do sex-linked male meiotic drivers contribute to intrinsic hybrid incompatibilities? Recent empirical studies from flies and rodents

26254
J. Kitano and K. Yoshida,  Current Opinion in Genetics and Development,  81:102068. 2023-06-22 08:05:04.
Intrinsic hybrid incompatibility is one of the important isolating barriers between species. In organisms with sex chromosomes, intrinsic hybrid incompatibility often follows two rules: Haldane’s rule and large-X effects. One explanation for these two rules is that sex chromosomes are hotspots for meiotic drivers that can cause intrinsic hybrid incompatibility between geographically isolated populations. Although this hypothesis seems plausible and several empirical data are consistent with it, we are still unsure whether such mechanisms occur in nature, particularly with respect to speciation with gene flow. Here, we review empirical studies that have investigated the roles of meiotic drive in sex-chromosome evolution and speciation and propose future studies necessary for testing this hypothesis.

Developing methods for chilling, compacting, and sterilizing adult Aedes aegypti (Diptera: Culicidae) and comparing mating competitiveness between males sterilized as adults versus pupae for sterile male release

26602
D. A. Tussey, R. Morreale, D. O. Carvalho, S. Stenhouse, A. M. Lloyd, D. F. Hoel and D. A. Hahn,  Journal of Medical Entomology,  2023-06-21 13:03:55.
The yellow fever mosquito, Aedes aegypti L., can transmit several pathogens responsible for human diseases. With insecticide resistance development becoming a concern, alternative control strategies are needed for Ae. aegypti. Sterile insect technique (SIT) is an increasingly popular option being explored. However, logistical issues in mass production and sterilization make it difficult to maintain a SIT program. Male mosquitoes are typically irradiated as pupae because this is the earliest developmental point at which females can be separated from males, but asynchrony in pupation and high variability in pupal responses to irradiation based on pupal age make it difficult to sterilize mass quantities of pupae on a regular schedule in a rearing facility. Young adult mosquitoes have wider windows for irradiation sterilization than pupae, which can allow facilities to have fixed schedules for irradiation. We produced a workflow for adult Ae. aegypti irradiation in a mosquito control district with an operational SIT program that currently irradiates pupae. The impacts of chilling, compaction, and radiation dose on survival were all assessed before combining them into a complete adult irradiation protocol. Males chilled up to 16 h prior to compaction and compacted to 100 males/cm3 during radiation resulted in low mortality. Males irradiated as adults had increased longevity and similar sterility compared to males irradiated as pupae. Additionally, males sterilized as adults were more sexually competitive than males sterilized as pupae. Thus, we have shown that irradiating adult males can be a viable option to increase the efficiency of this operational mosquito SIT program.

Regulatory logic of endogenous RNAi in silencing de novo genomic conflicts

26252
J. Vedanayagam, C. J. Lin, R. Papareddy, M. Nodine, A. S. Flynt, J. Wen and E. C. Lai,  PLOS Genetics,  19:e1010787. 2023-06-21 07:57:17.
Although the biological utilities of endogenous RNAi (endo-RNAi) have been largely elusive, recent studies reveal its critical role in the non-model fruitfly Drosophila simulans to suppress selfish genes, whose unchecked activities can severely impair spermatogenesis. In particular, hairpin RNA (hpRNA) loci generate endo-siRNAs that suppress evolutionary novel, X-linked, meiotic drive loci. The consequences of deleting even a single hpRNA (Nmy) in males are profound, as such individuals are nearly incapable of siring male progeny. Here, comparative genomic analyses of D. simulans and D. melanogaster mutants of the core RNAi factor dcr-2 reveal a substantially expanded network of recently-emerged hpRNA-target interactions in the former species. The de novo hpRNA regulatory network in D. simulans provides insight into molecular strategies that underlie hpRNA emergence and their potential roles in sex chromosome conflict. In particular, our data support the existence of ongoing rapid evolution of Nmy/Dox-related networks, and recurrent targeting of testis HMG Box loci by hpRNAs. Importantly, the impact of the endo-RNAi network on gene expression flips the convention for regulatory networks, since we observe strong derepression of targets of the youngest hpRNAs, but only mild effects on the targets of the oldest hpRNAs. These data suggest that endo-RNAi are especially critical during incipient stages of intrinsic sex chromosome conflicts, and that continual cycles of distortion and resolution may contribute to speciation.

Effects of radiation on the fitness, sterility and arbovirus susceptibility of a Wolbachia-free Aedes albopictus strain for use in the Sterile Insect Technique

25867
D. J. Zhang, S. Yan, H. Yamada, Y. Wu, G. Wang, Q. D. Feng, D. Paerhande, H. Maiga, J. Bouyer, J. Qian, Z. D. Wu and X. Y. Zheng,  Pest Management Science,  2023-06-15 08:49:29.
BACKGROUND: The sterile insect technique (SIT) is a green and species-specific insect pest control technique that suppresses target populations by releasing factory-reared, radio-sterilized males into the wild. Once released, it is important to be able to distinguish the released males from the wild males for monitoring purposes. Several methods to mark the sterile males exist. However, most have limitations due to monetary, process efficiency, or insect quality. Aedes albopictus is naturally infected with Wolbachia at a high prevalence. Therefore, the elimination of Wolbachia can serve as a biomarker to distinguish the factory-reared male mosquitoes from wild conspecifics. RESULTS: In this study, a Wolbachia-free Ae. albopictus GT strain was developed and its fitness evaluated, which was found to be comparable to the wild GUA strain. In addition, GT male mosquitoes were irradiated at the adult stage and a dose of 20 Gy or more induced over 99% sterility. Moreover, a dose of 30 Gy (almost completely sterilizing male and female mosquitoes) had limited effects on the mating competitiveness of GT males and vector competence of GT females, respectively. However, radiation reduced mosquito longevity, regardless of its sex. CONCLUSION: Our results indicated that the Ae. albopictus GT strain can be distinguished from the wild mosquitoes based on Wolbachia status and shows similar fitness, radio-sensitivity and arbovirus susceptibility to the GUA strain, indicating that it is feasible to use the GT strain to suppress Ae. albopictus populations for SIT programmes. This article is protected by copyright. All rights reserved.

CRISPR-based gene drives generate super-Mendelian inheritance in the disease vector Culex quinquefasciatus

25865
T. Harvey-Samuel, X. Feng, E. M. Okamoto, D.-K. Purusothaman, P. T. Leftwich, L. Alphey and V. M. Gantz,  bioRxiv,  2023.06.12.544656. 2023-06-15 08:40:13.
Culex mosquitoes pose a significant public health threat as vectors for a variety of diseases including West Nile virus and lymphatic filariasis, and transmit pathogens threatening livestock, companion animals, and endangered birds. Rampant insecticide resistance makes controlling these mosquitoes challenging and necessitates the development of new control strategies. Gene drive technologies have made significant progress in other mosquito species, although similar advances have been lagging in Culex. Here we test the first CRISPR-based homing gene drive for Culex quinquefasciatus, demonstrating the possibility of using this technology to control Culex mosquitoes. Our results show that the inheritance of two split-gene-drive transgenes, targeting different loci, are biased in the presence of a Cas9-expressing transgene although with modest efficiencies. Our findings extend the list of disease vectors where engineered homing gene drives have been demonstrated to include Culex alongside Anopheles and Aedes, and pave the way for future development of these technologies to control Culex mosquitoes

CRISPR/Cas9-based split homing gene drive targeting doublesex for population suppression of the global fruit pest Drosophila suzukii

25710
A. K. Yadav, C. Butler, A. Yamamoto, A. A. Patil, A. L. Lloyd and M. J. Scott,  Proc Natl Acad Sci U S A,  120:e2301525120. 2023-06-13 10:38:33.
Genetic-based methods offer environmentally friendly species-specific approaches for control of insect pests. One method, CRISPR homing gene drive that target genes essential for development, could provide very efficient and cost-effective control. While significant progress has been made in developing homing gene drives for mosquito disease vectors, little progress has been made with agricultural insect pests. Here, we report the development and evaluation of split homing drives that target the doublesex (dsx) gene in Drosophila suzukii, an invasive pest of soft-skinned fruits. The drive component, consisting of dsx single guide RNA and DsRed genes, was introduced into the female-specific exon of dsx, which is essential for function in females but not males. However, in most strains, hemizygous females were sterile and produced the male dsx transcript. With a modified homing drive that included an optimal splice acceptor site, hemizygous females from each of the four independent lines were fertile. High transmission rates of the DsRed gene (94 to 99%) were observed with a line that expressed Cas9 with two nuclear localization sequences from the D. suzukii nanos promoter. Mutant alleles of dsx with small in-frame deletions near the Cas9 cut site were not functional and thus would not provide resistance to drive. Finally, mathematical modeling showed that the strains could be used for suppression of lab cage populations of D. suzukii with repeated releases at relatively low release ratios (1:4). Our results indicate that the split CRISPR homing gene drive strains could potentially provide an effective means for control of D. suzukii populations.

Sequence and expression analysis of the spermatogenesis-specific gene cognates, wampa and Prosα6T, in Drosophila suzukii

26182
Q. Xia, K. Tariq, D. A. Hahn and A. M. Handler,  Genetica,  2023-06-10 12:20:00.
The sterile insect technique (SIT) is a highly effective biologically-based method for the population suppression of highly invasive insect pests of medical and agricultural importance. The efficacy of SIT could be significantly enhanced, however, by improved methods of male sterilization that avoid the fitness costs of irradiation. An alternative sterilization method is possible by gene-editing that targets genes essential for sperm maturation and motility, rendering them nonfunctional, similar to the CRISPR-Cas9 targeting of β2-tubulin in the genetic model system, Drosophila melanogaster. However, since genetic strategies for sterility are susceptible to breakdown or resistance in mass-reared populations, alternative targets for sterility are important for redundancy or strain replacement. Here we have identified and characterized the sequence and transcriptional expression of two genes in a Florida strain of Drosophila suzukii, that are cognates of the D. melanogaster spermatocyte-specific genes wampa and Prosalpha6T. Wampa encodes a coiled-coil dynein subunit required for axonemal assembly, and the proteasome subunit gene, Prosalpha6T, is required for spermatid individualization and nuclear maturation. The reading frames of these genes differed from their NCBI database entries derived from a D. suzukii California strain by 44 and 8 nucleotide substitutions/polymorphisms, respectively, though all substitutions were synonymous resulting in identical peptide sequences. Expression of both genes is predominant in the male testis, and they share similar transcriptional profiles in adult males with β2-tubulin. Their amino acid sequences are highly conserved in dipteran species, including pest species subject to SIT control, supporting their potential use in targeted male sterilization strategies. © 2023, This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.

The attitudes of young adults towards mammalian predator control and Predator Free 2050 in Aotearoa New Zealand

26186
L. Dickie and F. Medvecky,  Australasian Journal of Environmental Management,  2023-06-09 12:31:11.
Predator Free 2050 (PF2050) is an ambitious goal that aims to remove three types of invasive mammals from New Zealand by 2050. It will require a significant amount of funding, research, and support. Young adults will have an important role to play for this programme to be successful. Therefore, understanding the awareness and attitudes of young adults towards PF2050, and predator control, is an essential consideration. A survey of 1479 18- to 24-year-olds was conducted in 2017. The results showed that a higher percentage of young adults than members of the broader public view the small, introduced mammals as threats to New Zealand’s environment. Furthermore, this study highlights support for the control of feral, stray, and domestic cats. More focused research on attitudes towards cats is recommended to gauge which control methods are approved of by young adults. Indeed, methods appear to be a key factor to young adults supporting PF2050. The aerial distribution of poison was largely viewed negatively, and moderate concern was expressed about the targeted animal’s welfare. Interestingly, young adults appeared to be open to the use of gene editing and gene drive, although they expressed caution. Targeted communication towards young adults on toxins and genetic methods is recommended. © 2023 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

Modeling emergence of Wolbachia toxin-antidote protein functions with an evolutionary algorithm

26277
J. Beckmann, J. Gillespie and D. Tauritz,  Front Microbiol,  14:1116766. 2023-06-09 10:36:38.
Evolutionary algorithms (EAs) simulate Darwinian evolution and adeptly mimic natural evolution. Most EA applications in biology encode high levels of abstraction in top-down population ecology models. In contrast, our research merges protein alignment algorithms from bioinformatics into codon based EAs that simulate molecular protein string evolution from the bottom up. We apply our EA to reconcile a problem in the field of Wolbachia induced cytoplasmic incompatibility (CI). Wolbachia is a microbial endosymbiont that lives inside insect cells. CI is conditional insect sterility that operates as a toxin antidote (TA) system. Although, CI exhibits complex phenotypes not fully explained under a single discrete model. We instantiate in-silico genes that control CI, CI factors (cifs), as strings within the EA chromosome. We monitor the evolution of their enzymatic activity, binding, and cellular localization by applying selective pressure on their primary amino acid strings. Our model helps rationalize why two distinct mechanisms of CI induction might coexist in nature. We find that nuclear localization signals (NLS) and Type IV secretion system signals (T4SS) are of low complexity and evolve fast, whereas binding interactions have intermediate complexity, and enzymatic activity is the most complex. Our model predicts that as ancestral TA systems evolve into eukaryotic CI systems, the placement of NLS or T4SS signals can stochastically vary, imparting effects that might impact CI induction mechanics. Our model highlights how preconditions and sequence length can bias evolution of cifs toward one mechanism or another.

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