Keywords: Genetic incompatibilities
Changes in the frequency of facultative endosymbionts in insect populations: overview and applications
34922Hoffmann, Ary A.; Cooper, Brandon S., Entomologia Generalis, 45:351-368. 2025-06-23 14:41:27.
Many insect endosymbionts are facultative from the host perspective, and their population frequencies across time and space will depend on their transmission fidelity and effects on host fitness. These effects and transmission rates in turn depend on the environmental and host genetic contexts where the endosymbionts occur. Endosymbionts like Wolbachia and Cardinium affect host reproduction to produce transient or persistent presence/absence polymorphisms, while other endosymbionts like Regiella and Hamiltonella persist through providing host fitness benefits and transmitting horizontally. Evolutionary changes in hosts and endosymbionts affect these impacts and endosymbiont polymorphisms in host populations and host sexes. We review this diversity of endosymbiont-host interactions and their influence on the usefulness of endosymbionts for applied strategies. Current strategies focus on endosymbionts driving useful traits to fixation (particularly Wolbachia suppression of arbovirus transmission by mosquitoes) or endosymbionts suppressing populations due to infected males sterilising females. Transinfected endosymbionts sourced from one species and microinjected into another have proven effective in these Wolbachia-mosquito strategies. Novel strategies involving transinfected Rickettsiella, Regiella and Wolbachia may decrease the impacts of pest invertebrates by suppressing pest numbers, reducing the capacity of vector hosts to transmit plant viral diseases or bolstering the effectiveness of natural enemies. Because many endosymbionts are already present in the environment, their applied use raises fewer safety concerns when compared to genetic modification, as supported by more than 13 years of field experiences with Wolbachia in mosquitoes that have not raised major concerns.
Drones To Deliver Millions Of Mosquitoes to Prevent Bird Extinctions In Hawai‘i
34913GrrlScientist, Forbes, 2025-06-11 19:19:54.
In a brilliant demonstration of multidisciplinary collaboration, a conservation program to save Hawai’i’s critically endangered native bird species has taken another step forward. After a team of scientists created “reproductively incompatible” male mosquitoes in the lab, the next challenge was to safely deliver them to where they would most effectively suppress mosquito populations in Hawai’i. “Reproductively incompatible” male mosquitoes are created by infecting their mothers with the bacteria, Wolbachia. This bacteria, which naturally occurs in many wild insect species, interferes with reproduction in mosquitoes by making the Wolbachia-males reproductively incompatible with normal wild-type female mosquitoes. (But the males can successfully reproduce with females infected with the same strain of Wolbachia – that is how the millions of mosquitoes needed for this project are produced in the lab.) When these reproductively incompatible Wolbachia-male mosquitoes mate with normal wild female mosquitoes, the resulting eggs cannot hatch, thereby reducing the mosquito population. The good news in this story (which will become important as you read on) is that male mosquitoes (regardless of whether they carry Wolbachia) do not bite or transmit disease, and feed only on plant juices and nectar for survival and energy. On the other hand, female mosquitoes do bite because they need a fresh blood meal to produce eggs. Additionally, because mosquitoes infected with Wolbachia bacteria are not genetically modified, and because Wolbachia bacteria naturally occur in 60% or more wild insects, these mosquitoes are safe.
Transformation of meiotic drive into hybrid sterility in Drosophila
30352Jackson Bladen, Hyuck-Jin Nam, Nitin Phadnis, bioRxiv, 2024-05-21 19:05:25.
Hybrid male sterility is one of the fastest evolving intrinsic reproductive barriers between recently isolated populations. A leading explanation for the evolution of hybrid male sterility involves genomic conflicts with meiotic drivers in the male germline. There are, however, few examples directly linking meiotic drive to hybrid sterility. Here, we report that the Sex-Ratio chromosome of Drosophila pseudoobscura, which causes X-chromosome drive within the USA subspecies, causes near complete male sterility when moved into the genetic background of the Bogota subspecies. In addition, we show that this new form of sterility is genetically distinct from the sterility of F1 hybrid males in crosses between USA males and Bogota females. Our observations provide a tractable study system where non-cryptic drive within species is transformed into strong hybrid sterility between very young subspecies.
A natural gene drive element confers speciation in rice
28000Y. Li, S. Liu and R. Shen, Chinese Science Bulletin, 68:3400-3402. 2023-09-27 08:30:59.
For a long time, although many important advances have been made in the field of rice hybrid sterility, the specific molecular mechanism behind the "killer-protector"/ "poison-antidote" model has been unclear. Recently, the team of Academician Wan Jianmin of Nanjing Agricultural University identified a major locus RHS12 controlling pollen sterility of indica-japonica hybrids. This site belongs to the same locus as the recently cloned pf12 and Se[16,17]. Genetic analysis revealed that RHS12 consists of two closely linked genes, iORF3/DUYAO and iORF4/JIEYAO. These two genes are commonly found in indica rice genome, but not in some japonica rice genomes. iORF3 (DUYAO) encodes a poison protein localized in mitochondria. DUYAO interacts with OsCOX11, a core functional protein in the mitochondrial respiratory chain, to cause mitochondrial dysfunction and induce programmed cell death (program cell death, PCD) leading to pollen abortion. iORF4 (JIEYAO) encodes an antidote protein that interacts with the DUYAO protein to bring DUYAO to the autophagosome for degradation, thereby releasing OsCOX11 for normal pollen development (Fig. 1). Therefore, during the pollen development of indica-japonica hybrids, the pollen of japonica type without this pair of genes was selectively aborted, while the pollen of indica type with this pair of genes developed normally. For the first time, this study completely and clearly clarified the mechanism of RHS12 regulating rice hybrid sterility from the genetic, cellular and molecular levels, and achieved a major breakthrough in this field.
The role of conflict in shaping plant biodiversity
27753J. M. Coughlan, New Phytologist, 2023-09-04 07:45:46.
Although intrinsic postzygotic reproductive barriers can play a fundamental role in speciation, their underlying evolutionary causes are widely debated. One hypothesis is that incompatibilities result from genomic conflicts. Here, I synthesize the evidence that conflict generates incompatibilities in plants, thus playing a creative role in plant biodiversity. While much evidence supports a role for conflict in several classes of incompatibility, integrating knowledge of incompatibility alleles with natural history can provide further essential tests. Moreover, comparative work can shed light on the relative importance of conflict in causing incompatibilities, including the extent to which their evolution is repeatable. Together, these approaches can provide independent lines of evidence that conflict causes incompatibilities, cementing its role in plant speciation.
Hybrid incompatibilities in the anopheles gambiae species complex
24968A. Kriezis, Imperial College London, 2023-03-01 10:47:20.
Malaria is an infectious disease caused by parasites of the genus Plasmodium which is responsible for approximately 400,000 deaths annually, primarily in sub-Saharan Africa. Malaria is transmitted by mosquitoes belonging to the Anopheles gambiae species complex. While progress has been made to reduce the incidence of malaria, the emergence of insecticide resistance necessitates the development of novel vector control strategies. Gene drive technologies have seen significant advances in recent years, providing hope for their implementation in the near future. While gene flow has been identified between sibling species of the An. gambiae species complex, they are reproductively isolated by both pre- and post-zygotic isolation mechanisms. Interspecific crosses between most member species produce sterile hybrid males, in accordance with Haldane’s rule of speciation. The aim of this project was to support the development of gene drive technologies by investigating hybrid incompatibilities between two of the most significant vector species, Anopheles gambiae and Anopheles arabiensis. The potential for the introgression of genomic regions from one species into the genetic background of the other was investigated to help inform models regarding the spread of gene drives between sibling species. In addition, the identification of genetic elements involved in hybrid male sterility could provide potential targets for vector control strategies. Large autosomal regions were found to introgress and persist in interspecific genomes without a detectable fertility cost. In addition, the introduction of distinct autosomal regions of conspecific DNA into otherwise heterospecific genomes of hybrid males was found to overcome hybrid incompatibilities and partially restore fertility. While no specific genetic factors involved in hybrid incompatibilities could be identified, the results indicate that such factors are present at least on the X chromosome. Furthermore, the evidence suggests that asynapsis between interspecific homologous autosomes during gametogenesis plays a role in the manifestation of hybrid male sterility.
Engineering stringent genetic biocontainment of yeast with a protein stability switch
24034S. A. Hoffmann and Y. Cai, bioRxiv, 2022.11.24.517818. 2022-11-24 09:51:15.
Synthetic biology holds immense promise to tackle key problems we are facing, for instance in resource use, environmental health, and human health care. However, comprehensive safety measures are needed to deploy genetically engineered microorganisms in open-environment applications. Here, we describe a genetic biocontainment system based on conditional stability of essential proteins. We used a yeast-adapted destabilizing domain degron, which can be stabilized by estradiol addition (ERdd). Leveraging the yeast GFP collection and lab automation platforms, we ERdd-tagged 775 essential genes and screened for strains with estradiol dependent growth. Three genes, SPC110, DIS3 and RRP46, were found to be particularly suitable. Respective strains showed no growth defect in the presence of estradiol and strong growth inhibition in its absence. Of these, SPC110-ERdd offered the most stringent containment, with an escape frequency of 7.0x10-8, and full growth restoration at 100 nM estradiol. By systematically analysing the containment escapees, we identified the non- essential C-terminal region of SPC110 as target for escape mutations. Its removal decreased the escape frequency with a single ERdd tag further to 4.3x10-9. Combining SPC110-ERdd with a second ERdd tag on either DIS3 or RRP46 resulted in escape frequencies below the detection limit of the used assay (<2x10-10). Being based on conditional protein stability, this approach is mechanistically orthogonal to previously reported intrinsic biocontainment systems. It thus can be readily combined with other systems, for instance ones based on transcriptional or translational control of essential gene expression, to achieve multiplexed, extremely stringent control over the survival of engineered organisms.Competing Interest StatementThe authors have declared no competing interest.
Modeling-informed Engineered Genetic Incompatibility strategies to overcome resistance in the invasive Drosophila suzukii
28350A. Sychla, N. R. Feltman, W. D. Hutchison and M. J. Smanski, Frontiers in Insect Science, 2. 2022-11-22 10:46:03.
Engineered Genetic Incompatibility (EGI) is an engineered extreme underdominance genetic system wherein hybrid animals are not viable, functioning as a synthetic speciation event. There are several strategies in which EGI could be leveraged for genetic biocontrol of pest populations. We used an agent-based model of Drosophila suzukii (Spotted Wing Drosophila) to determine how EGI would fare with high rates of endemic genetic resistance alleles. We discovered a surprising failure mode wherein field-generated females convert an incompatible male release program into a population replacement gene drive. Local suppression could still be attained in two seasons by tailoring the release strategy to take advantage of this effect, or alternatively in one season by altering the genetic design of release agents. We show in this work that data from modeling can be utilized to recognize unexpected emergent phenomena and a priori inform genetic biocontrol treatment design to increase efficacy.
Evolution of eukaryotic centromeres by drive and suppression of selfish genetic elements
21559T. Kumon and M. A. Lampson, Seminars in Cell and Developmental Biology, 2022-03-25 12:12:40.
Despite the universal requirement for faithful chromosome segregation, eukaryotic centromeres are rapidly evolving. It is hypothesized that rapid centromere evolution represents an evolutionary arms race between selfish genetic elements that drive, or propagate at the expense of organismal fitness, and mechanisms that suppress fitness costs. Selfish centromere DNA achieves preferential inheritance in female meiosis by recruiting more effector proteins that alter spindle microtubule interaction dynamics. Parallel pathways for effector recruitment are adaptively evolved to suppress functional differences between centromeres. Opportunities to drive are not limited to female meiosis, and selfish transposons, plasmids and B chromosomes also benefit by maximizing their inheritance. Rapid evolution of selfish genetic elements can diversify suppressor mechanisms in different species that may cause hybrid incompatibility.
Genetically engineered insects with sex-selection and genetic incompatibility enable population suppression
20286A. Upadhyay, N. R. Feltman, A. Sychla, A. Janzen, S. R. Das, M. Maselko and M. Smanski, eLife, 11. 2022-02-02 11:49:30.
Engineered Genetic Incompatibility (EGI) is a method to create species-like barriers to sexual reproduction. It has applications in pest control that mimic Sterile Insect Technique when only EGI males are released. This can be facilitated by introducing conditional female-lethality to EGI strains to generate a sex-sorting incompatible male system (SSIMS). Here, we demonstrate a proof of concept by combining tetracycline-controlled female lethality constructs with a pyramus-targeting EGI line in the model insect Drosophila melanogaster. We show that both functions (incompatibility and sex-sorting) are robustly maintained in the SSIMS line and that this approach is effective for population suppression in cage experiments. Further we show that SSIMS males remain competitive with wild-type males for reproduction with wild-type females, including at the level of sperm competition.
Transmission distortion and genetic incompatibilities between alleles in a multigenerational mouse advanced intercross line
19320D. Arends, S. Kärst, S. Heise, P. Korkuc, D. Hesse and G. A. Brockmann, Genetics, 2021-11-15 14:07:56.
While direct additive and dominance effects on complex traits have been mapped repeatedly, additional genetic factors contributing to the heterogeneity of complex traits have been scarcely investigated. To assess genetic background effects, we investigated transmission ratio distortions (TRDs) of alleles from parent to offspring using an advanced intercross line (AIL) of an initial cross between the mouse inbred strains C57BL/6NCrl (B6N) and BFMI860-12 (BFMI). 341 males of generation 28 and their respective 61 parents and 66 grandparents were genotyped using Mega Mouse Universal Genotyping Arrays (MegaMUGA). TRDs were investigated using allele transmission asymmetry tests, and pathway overrepresentation analysis was performed. Sequencing data was used to test for overrepresentation of non-synonymous SNPs in TRD regions. Genetic incompatibilities were tested using the Bateson-Dobzhansky-Muller two-locus model. 62 TRD regions were detected, many in close proximity to the telocentric centromere. TRD regions contained 44.5% more non-synonymous SNPs than randomly selected regions (182 vs. 125.9 ± 17.0, P < 1x10-4). Testing for genetic incompatibilities between TRD regions identified 29 genome-wide significant incompatibilities between TRD regions (P(BF) < 0.05). Pathway overrepresentation analysis of genes in TRD regions showed that DNA methylation, epigenetic regulation of RNA, and meiotic/meiosis regulation pathways were affected independent of the parental origin of the TRD. Paternal BFMI TRD regions showed overrepresentation in the small interfering RNA (siRNA) biogenesis and in the metabolism of lipids and lipoproteins. Maternal B6N TRD regions harbored genes involved in meiotic recombination, cell death, and apoptosis pathways. The analysis of genes in TRD regions suggests the potential distortion of protein-protein interactions influencing obesity and diabetic retinopathy as a result of disadvantageous combinations of allelic variants in Aass, Pgx6 and Nme8. Using an AIL significantly improves the resolution at which we can investigate TRD. Our analysis implicates distortion of protein-protein interactions as well as meiotic drive as the underlying mechanisms leading to the observed TRD in our AIL. Furthermore, genes with large amounts of non-synonymous SNPs located in TRD regions are more likely to be involved in pathways that are related to the phenotypic differences between the parental strains. Genes in these TRD regions provide new targets for investigating genetic adaptation, protein-protein interactions, and determinants of complex traits such as obesity.
A Sterile Solution: How Crispr Could Protect Wild Salmon
17821L. Abend, UNDARK, 2021-07-21 14:44:32.
In an attempt to prevent escaped fish from interbreeding with their wild counterparts and threatening the latter’s genetic diversity, molecular biologist Anna Wargelius and her team at the Institute of Marine Research in Norway have spent years working on ways to induce sterility in Atlantic salmon. Farmed salmon that cannot reproduce, after all, pose no threat to the gene pool of wild stocks, and Wargelius has successfully developed a technique that uses the gene-editing technology Crispr to prevent the development of the cells that would otherwise generate functioning sex organs. In fact, Wargelius’ team was a little too successful. To be financially viable, commercial fish farms need at least some of their stock to reproduce. So the scientists went a step further, developing a method of temporarily reversing the modification they had already made. They’ve created what they call “sterile parents.” The term may sound like an oxymoron, but the sterile parents have the potential to solve one of the most pressing problems facing salmon aquaculture, both in Norway and around the world. Wargelius says it could be up to a decade before the results of her work are commercially available, but once they are, they have the potential to make an already burgeoning food source markedly more friendly on the environment. And by prioritizing environmental concerns and employing a technique that simply turns off a gene rather than introducing one from a different species, Wargelius and her team may contribute to a shift in how genetic engineering is perceived in Norway, a country with some of the strictest regulations regarding genetically modified organisms on the books.
Gene tech to prevent crossbreeding could safely harness the power of gene drives
17212I. l. Guillou, The Science Advisory Board, 2021-06-04 15:52:06.
A new gene engineering technology could allow scientists to harness the benefits of releasing genetically modified animals into the wild without the risk of uncontrolled spread. The new study, published in the journal Nature Communications on June 2, could help in the battle against the spread of diseases like malaria. The advent of the genetic age offers the tantalizing prospect of being able to genetically alter animals, such as pests and disease vectors, to reduce the harm they cause to society. However, any technology with the ability to make a difference on a significant scale would also have the potential to cause serious damage if it went out of control. Gene drives are one such technology. These genetic modifications are designed to spread through a population quickly and rely on the CRISPR-Cas9 gene editing system to make a duplicate copy of the gene drive on the partner chromosome. This means that all offspring inherit the gene, compared to only 50% through normal genetic inheritance. However, there are concerns about the effect of releasing such gene drives into the wild. Unintended consequences, potentially due to mutations or ecological shifts, could be irreversible. This has led geneticists to search for new versions of gene drives that can prevent unrestricted spread by stopping engineered animals from crossbreeding with the wild population. Approaches previously developed have severe limitations, such as not working in multicellular organisms, causing high fitness costs, or working incompletely.
Scientists design new gene drive to stop the transmission of devastating diseases
17292E. Henderson, AZO Life Sciences, 2021-06-03 10:42:37.
CRISPR-based technologies offer enormous potential to benefit human health and safety, from disease eradication to fortified food supplies. As one example, CRISPR-based gene drives, which are engineered to spread specific traits through targeted populations, are being developed to stop the transmission of devastating diseases such as malaria and dengue fever. But many scientists and ethicists have raised concerns over the unchecked spread of gene drives. Once deployed in the wild, how can scientists prevent gene drives from uncontrollably spreading across populations like wildfire? Now, scientists at the University of California San Diego and their colleagues have developed a gene drive with a built-in genetic barrier that is designed to keep the drive under control. Led by molecular geneticist Omar Akbari's lab, the researchers engineered synthetic fly species that, upon release in sufficient numbers, act as gene drives that can spread locally and be reversed if desired.
Synthetic SPECIES developed for use as a confinable gene drive
17179University of California - San Diego, ScienceDaily, 2021-06-02 20:04:29.
CRISPR-based technologies offer enormous potential to benefit human health and safety, from disease eradication to fortified food supplies. As one example, CRISPR-based gene drives, which are engineered to spread specific traits through targeted populations, are being developed to stop the transmission of devastating diseases such as malaria and dengue fever. But many scientists and ethicists have raised concerns over the unchecked spread of gene drives. Once deployed in the wild, how can scientists prevent gene drives from uncontrollably spreading across populations like wildfire? Now, scientists at the University of California San Diego and their colleagues have developed a gene drive with a built-in genetic barrier that is designed to keep the drive under control. Led by molecular geneticist Omar Akbari's lab, the researchers engineered synthetic fly species that, upon release in sufficient numbers, act as gene drives that can spread locally and be reversed if desired.
Number of Project Wolbachia mosquitoes released is constantly reviewed to maintain suppression of dengue: NEA
16388N. L. Ching, today, 2021-02-09 15:12:34.
Project Wolbachia – Singapore has yielded promising results so far.Releases of non-biting male Wolbachia-Aedes mosquitoes have suppressed the urban Aedes aegypti mosquito populations in study sites at Tampines and Yishun by up to 90 per cent, and we have observed 58 to 74 per cent less dengue cases in 2020 in areas where releases have been ongoing for at least a year compared to areas without releases. However, this does not mean that there will be no dengue cases in the study sites, especially in the initial period, because it takes several months for the releases to bring down the dengue mosquito population.While some residents at the release sites have noticed more non-biting mosquitoes around their homes, the released male mosquitoes do not bite, and the overall data shows a clear benefit — fewer dengue cases.
‘Clever Approach’: Scientists Create GM-Free Organisms Using Genetic Engineering
15955A. Paleja, The WIRE, 2021-01-11 17:07:06.
Farther to the north, researchers at the University of Minnesota have developed a novel way to resolve this problem. They used genetic engineering to create organisms for release that are not genetically modified. Maciej Maselko was a postdoctoral associate at the university when he was part of the study. “Slow and expensive regulatory approvals for GM insect release” inspired the team’s work, he told The Wire Science. “We looked for a way to get the benefits achieved with GM insect release but without needing to release GM insects.” He conceptualised the experiment with PhD scholar Siba Das and molecular biology professor Michael Smanski. The results were published in November 2020. In a typical control intervention, researchers release sterile male mosquitoes into the environment. These compete with wild males to mate with wild females. Mosquitoes mate only once in their lifetime. Since mating with sterile mosquitoes produces no offspring, the local mosquito population begins to fall. The methods to select these male mosquitoes to subsequently release are either labour intensive or need specialised equipment. The colony that scientists rear is also often three times larger than the number of males released. Third, a mosquito lives typically for 8-10 days. So scientists must select the males to release close to the site of intervention.
Selfing is the safest sex for Caenorhabditis tropicalis
15953L. M. Noble, J. Yuen, L. Stevens, N. D. Moya, R. Persaud, M. Moscatelli, J. L. Jackson, G. Zhang, R. Chitrakar, L. R. Baugh, C. Braendle, E. C. Andersen, H. S. Seidel and M. V. Rockman, eLife, 10:e62587. 2021-01-11 16:59:39.
We generated a chromosomal-scale genome for C. tropicalis and surveyed global diversity. Population structure is very strong, and islands of extreme divergence punctuate a genomic background that is highly homogeneous around the globe. Outbreeding depression in the laboratory is caused largely by multiple Medea-like elements, genetically consistent with maternal toxin/zygotic antidote systems. Loci with Medea activity harbor novel and duplicated genes, and their activity is modified by mito-nuclear background. Segregating Medea elements dramatically reduce fitness, and simulations show that selfing limits their spread. Frequent selfing in C. tropicalis may therefore be a strategy to avoid Medea-mediated outbreeding depression.
Ubiquitous Selfish Toxin-Antidote Elements in Caenorhabditis Species
15947E. Ben-David, P. Pliota, S. A. Widen, A. Koreshova, T. Lemus-Vergara, P. Verpukhovskiy, S. Mandali, C. Braendle, A. Burga and L. Kruglyak, Current Biology, 2021-01-07 16:57:04.
Here, we report the discovery of maternal-effect TAs in both C. tropicalis and C. briggsae, two distant relatives of C. elegans. In C. tropicalis, multiple TAs combine to cause a striking degree of intraspecific incompatibility: five elements reduce the fitness of >70% of the F2 hybrid progeny of two Caribbean isolates. We identified the genes underlying one of the novel TAs, slow-1/grow-1, and found that its toxin, slow-1, is homologous to nuclear hormone receptors. Remarkably, although previously known TAs act during embryonic development, maternal loading of slow-1 in oocytes specifically slows down larval development, delaying the onset of reproduction by several days. Finally, we found that balancing selection acting on linked, conflicting TAs hampers their ability to spread in populations, leading to more stable genetic incompatibilities. Our findings indicate that TAs are widespread in Caenorhabditis species and target a wide range of developmental processes and that antagonism between them may cause lasting incompatibilities in natural populations. We expect that similar phenomena exist in other animal species.
New insect species made via genetic engineering
15610L. Leffer, SCIENCELINE, 2020-12-18 15:47:16.
A biotech fast-forward button for evolution is on the horizon. Researchers say they have used a novel genetic engineering method to create several new species of fruit fly in the lab for the first time — an achievement which might help put a future without malaria and other insect-borne diseases within reach. The approach, called synthetic speciation, could prove useful in creating safer pest-control technologies, says Maciej Maselko, a postdoctoral fellow studying synthetic biology at Macquarie University. In one far-off scenario, according to Maselko, synthetic speciation might even be applied to generate designer organisms that could pollinate plants or even detect landmines. Maselko and his team published their findings September 8 in Nature Communications. “Speciation has occurred billions of times on the planet, but hasn’t been engineerable [before],” says Michael Smanski, a molecular biologist at the University of Minnesota and member of the research team. Maselko, Smanski and their colleagues have previously used a similar method to engineer “species like” differences in yeast in 2018, but their more recent results are the first time the concept has been proven possible in a multicellular animal. This method could produce untold numbers of new animal varieties within months rather than millennia, Smanski says.
Selfish genetic elements and male fertility
15183R. L. Verspoor, T. A. R. Price and N. Wedell, Philosophical Transactions of the Royal Society B-Biological Sciences, 375:7. 2020-10-20 14:40:03.
Selfish genetic elements (SGEs) are diverse and near ubiquitous in Eukaryotes and can be potent drivers of evolution. Here, we discuss SGEs that specifically act on sperm to gain a transmission advantage to the next generation. The diverse SGEs that affect sperm often impose costs on carrier males, including damaging ejaculates, skewing offspring sex ratios and in particular reducing sperm-competitive success of SGE-carrying males. How males and females tolerate and mitigate against these costs is a dynamic and expanding area of research. The intense intra-genomic conflict that these selfish elements generate could also have implications for male fertility and spermatogenesis more widely. This article is part of the theme issue 'Fifty years of sperm competition'.
Fruit fly breakthrough puts killer mozzies on notice
14812V. Tressider, The Lighthouse, 2020-10-19 15:34:08.
A new designer fruit fly paves the way for scientists to replace disease-carrying mosquitoes with harmless, genetically modified versions, says Macquarie University researcher Dr Maciej Maselko.
GeneConvene Global Collaborative Webinar Series | Gene Drive Technical Webinars
14347David O'Brochta and Hector Quemada, GeneConvene Global Collaborative, 2020-10-12 02:54:40.
A series of technical webinars on engineered gene drive technology research and development given by leading researchers in the field.
The Evolving Arsenal Against Mosquito-Born Diseases
14369J. Smith, Labiotech.eu, 2020-09-10 16:01:02.
As the global climate continues to warm, disease-spreading mosquitoes such as Aedes aegypti are expected to establish themselves in the US and Europe.
Mutant mosquitoes: GM insects ‘engineered’ in ‘new approach to pest control’
14337T. Fish, EXPRESS, 2020-09-09 18:44:38.
This cutting-edge research provides the foundations for plans to prevent genetically modified organisms from reproducing with wild organisms.
Engineering speciation events in insects may be used to control harmful pests
14328University of Minnesota, Phys Org, 2020-09-08 17:55:45.
A team of scientists led by Mike Smanski, Ph.D., in the College of Biological Sciences (CBS) has generated speciation events in fruit flies so that engineered strains can reproduce normally with each other, but mating with unmodified flies results in non-viable offspring.
Prospects and Pitfalls: Next-Generation Tools to Control Mosquito-Transmitted Disease
14366E. P. Caragata, S. Dong, Y. Dong, M. L. Simões, C. V. Tikhe and G. Dimopoulos, Annual Review of Microbiology, 74:455-475. 2020-09-08 15:57:19.
A diverse array of next-generation tools has been designed to eliminate mosquito populations or to replace them with mosquitoes that are less capable of transmitting key pathogens.
Non-GMO approach reduces cases of mosquito-borne dengue by 77%
14239GM Watch, GM Watch, 2020-08-31 13:55:39.
A randomized field trial found that mosquitoes infected with a natural bacterium called Wolbachia reduced cases of dengue by an "extraordinary" 77%.
Bacteria-Laced Mosquitoes Limit Spread of Dengue
14244A. Heidt, The Scientist, 2020-08-29 14:05:32.
Researchers have infected Aedes aegypti mosquitoes—the species responsible for passing on many diseases—with bacteria called Wolbachia with the intent of reducing the insects’ ability to pass on dengue to people.
Scientists infect mosquitoes with bacteria to stop the transmission of dengue fever in Indonesia, dropping infection rates by 77 percent
14250D. Avery, Daily Mail, 2020-08-28 14:15:52.
The team found that dengue infections were 77 percent lower in treated neighborhoods, compared to areas not exposed to the infected insects.
The mosquito strategy that could eliminate dengue
14170E. Callaway, Nature, 2020-08-27 14:19:52.
The study, conducted in an Indonesia city, showed that releasing mosquitoes modified to carry a bacterium called Wolbachia, which stops the insects from transmitting some viruses, led to a steep drop in cases of dengue fever.
Researchers Find New Approach To Control Dengue, Zika By Genetically Modifying Mosquitoes
14247N. Sharma, R. Republicworld.com, 2020-08-27 14:11:56.
A new study carried out in Indonesia has shown that dengue infection rates decreased in regions where the genetically modified mosquitoes were introduced.
Australian research takes aim at dengue, another killer virus
14226E. Connors, Finanacial Review, 2020-08-26 20:22:39.
Australian researchers have teamed up with Indonesian philanthropists to strike a blow against dengue fever, the deadly disease that was a growing scourge in south-east Asia and South America long before COVID-19.
Australian scientists slash dengue fever in Indonesia by infecting mosquitoes with bacteria
14224A. Barker, ABC News, 2020-08-26 20:17:56.
Australian scientists may have found the secret to eradicating dengue fever, with a lengthy trial in Indonesia drastically reducing the incidence of the mosquito-borne virus.
Engineered Reproductively Isolated Species Drive Reversible Population Replacement
13837A. Buchman, I. Shriner, T. Yang, J. Liu, I. Antoshechkin, J. M. Marshall, M. W. Perry and O. S. Akbari, bioRxiv, 2020.08.09.242982. 2020-08-10 15:42:26.
Engineered reproductive species barriers are useful for impeding gene flow and driving desirable genes into wild populations in a reversible threshold-dependent manner. We engineer multiple reproductively isolated SPECIES and demonstrate their threshold-dependent gene drive capabilities in D. melanogaster.
Ubiquitous selfish toxin-antidote elements in Caenorhabditis species
13751E. Ben-David, P. Pliota, S. A. Widen, A. Koreshova, T. Lemus-Vergara, P. Verpukhovskiy, S. Mandali, C. Braendle, A. Burga and L. Kruglyak, bioRxiv, 2020.08.06.240564. 2020-08-07 17:38:23.
We discovered five maternal-effect Toxin/Antidotes (TAs) in the nematode Caenorhabditis tropicalis and one in C. briggsae. Unlike previously reported TAs, five of these novel toxins do not kill embryos but instead cause larval arrest or developmental delay. Our results show that TAs are common in Caenorhabditis species, target a wide range of developmental processes, and may act as barriers preventing gene flow.
Artificial Selection Finds New Hypotheses for the Mechanism of Wolbachia-Mediated Dengue Blocking in Mosquitoes
13600S. A. Ford, I. Albert, S. L. Allen, S. F. Chenoweth, M. Jones, C. Koh, A. Sebastian, L. T. Sigle and E. A. McGraw, Frontiers in Microbiology, 11:1456. 2020-07-07 13:18:12.
We recently used experimental evolution to reveal that Wolbachia-mediated dengue blocking could be selected upon in the A. aegypti host and showed evidence that strong levels of blocking could be maintained by natural selection. In this study, we investigate the genetic variation associated with blocking and use these analyses to generate testable hypotheses surrounding the mechanism of Wolbachia-mediated dengue blocking.
Engineering multiple species-like genetic incompatibilities in insects
12543M. Maselko, N. Feltman, A. Upadhyay, A. Hayward, S. Das, N. Myslicki, A. J. Peterson, M. B. O’Connor and M. J. Smanski, bioRxiv, 2020-04-05 17:32:23.
Speciation constrains the flow of genetic information between populations of sexually reproducing organisms. Gaining control over mechanisms of speciation would enable new strategies to manage wild populations of disease vectors, agricultural pests, and invasive species. Additionally, such control would provide safe biocontainment of transgenes and gene drives. Natural speciation can be driven by pre-zygotic barriers that prevent fertilization or by post-zygotic genetic incompatibilities that render the hybrid progeny inviable or sterile. Here we demonstrate a general approach to create engineered genetic incompatibilities (EGIs) in the model insect Drosophila melanogaster. Our system couples a dominant lethal transgene with a recessive resistance allele. EGI strains that are homozygous for both elements are fertile and fecund when they mate with similarly engineered strains, but incompatible with wild-type strains that lack resistant alleles. We show that EGI genotypes can be tuned to cause hybrid lethality at different developmental life-stages. Further, we demonstrate that multiple orthogonal EGI strains of D. melanogaster can be engineered to be mutually incompatible with wild-type and with each other. Our approach to create EGI organisms is simple, robust, and functional in multiple sexually reproducing organisms.
The potential cost-effectiveness of controlling dengue in Indonesia using wMel Wolbachia released at scale: a modelling study
14326O. J. Brady, D. D. Kharisma, N. N. Wilastonegoro, K. M. Reilly, E. Hendricx, L. S. Bastos, L. Yakob and D. S. Shepard, medRxiv, 2020.01.11.20017186. 2020-01-16 17:55:32.
Wolbachia releases in high density urban areas is expected to be highly cost-effective and could potentially be the first cost saving intervention for dengue. Sites with strong public health infrastructure, fiscal capacity, and community support should be prioritized.
Standard deviations: The biological bases of transmission ratio distortion
6179L. Fishman and M. McIntosh, Annual Review of Genetics, 53:347-372. 2019-09-10 18:59:40.
The rule of Mendelian inheritance is remarkably robust, but deviations from the equal transmission of alternative alleles at a locus [a.k.a. transmission ratio distortion (TRD)] are also commonly observed in genetic mapping populations. Such TRD reveals locus-specific selection acting at some point between the diploid heterozygous parents and progeny genotyping and therefore can provide novel insight into otherwise-hidden genetic and evolutionary processes. Most of the classic selfish genetic elements were discovered through their biasing of transmission, but many unselfish evolutionary and developmental processes can also generate TRD. In this review, we describe methodologies for detecting TRD in mapping populations, detail the arenas and genetic interactions that shape TRD during plant and animal reproduction, and summarize patterns of TRD from across the genetic mapping literature. Finally, we point to new experimental approaches that can accelerate both detection of TRD and characterization of the underlying genetic mechanisms.
Transmission ratio distortion is frequent in Arabidopsis thaliana controlled crosses
3942Seymour, DKC, E.; Arioz, B. I.; Koenig, D.; Weigel, D., Heredity, 122:294-304. 2019-01-20 00:00:00.
The equal probability of transmission of alleles from either parent during sexual reproduction is a central tenet of genetics and evolutionary biology. Yet, there are many cases where this rule is violated. The preferential transmission of alleles or genotypes is termed transmission ratio distortion (TRD). Examples of TRD have been identified in many species, implying that they are universal, but the resolution of species-wide studies of TRD are limited. We have performed a species-wide screen for TRD in over 500 segregating F-2 populations of Arabidopsis thaliana using pooled reduced-representation genome sequencing. TRD was evident in up to a quarter of surveyed populations. Most populations exhibited distortion at only one genomic region, with some regions being repeatedly affected in multiple populations. Our results begin to elucidate the species-level architecture of biased transmission of genetic material in A. thaliana, and serve as a springboard for future studies into the biological basis of TRD in this species.
Making a murderer: The evolutionary framing of hybrid gamete-killers
3949Sweigart, ALB, Yaniv; Fishman, Lila, Trends in Genetics, 35:245-252. 2019-01-07 00:00:00.
Recent molecular investigations of hybrid incompatibilities have revealed fascinating patterns of genetic interactions that have been interpreted as the remnants of a history of selfish evolution. Instead of framing hybrid incompatibilities in light of genetic conflict, we advocate assuming their innocence. Researchers must build a strong theory for each case, supported by population genetic evidence, such that the role of conflict in the evolution of a hybrid incompatibility can be proven beyond reasonable doubt. This will require careful investigation of the evolutionary history of these incompatibilities, a reckoning of how the reproductive biology of study organisms impacts on the likelihood of genetic conflict, and molecular evidence of the rapid selfish spread of these alleles.
Genetic control of invasive plants species using selfish genetic elements
13612K. A. Hodgins, L. Rieseberg and S. P. Otto, Evolutionary Applications, 2:555-569. 2009-10-30 13:00:19.
Invasive plants cause substantial environmental damage and economic loss. Here, we explore the possibility that a selfish genetic element found in plants called cytoplasmic male sterility (CMS) could be exploited for weed control. We developed an analytical model and a spatial simulation to assess the use of CMS alleles to manage weed populations.
TSETSE GENETICS: Contributions to Biology, Systematics, and Control of Tsetse Flies
26199R. H. Gooding and E. S. Krafsur, Annual Review of Entomology, 50:101-123. 2005-01-01 14:04:26.
Tsetse flies (Diptera: Glossinidae) constitute a small, ancient taxon of exclusively hematophagous insects that reproduce slowly and viviparously. Because tsetse flies are the only vectors of pathogenic African trypanosomes, they are a potent and constant threat to humans and livestock over much of sub-Saharan Africa. Despite their low fecundity, tsetse flies demonstrate great resilience, which makes population suppression expensive, transient, and beyond the capacities of private and public sectors to accomplish, except over small areas. Nevertheless, control measures that include genetic methods are under consideration at national and supranational levels. There is a pressing need for sufficient laboratory cultures of tsetse flies and financial support to carry out genetic research. Here we review tsetse genetics from organismal and population points of view and identify some research needs.
Experiments in the hybridisation of tsetse-flies (Glossina, Diptera) and the possibility of a new method of control.
6139F. L. Vanderplank, Transactions of the Royal Entomological Society of London, 98:1-18. 1947-01-02 21:38:18.
Hybridisation of Glossina morsitans Westwood, G. swynnertoni Austen and G. pallidipes Austen was attempted in order to discover(a) Whether the three could be regarded as distinct species or as sub-species of morsitans ; (b) Whether they would mate freely with one another, and if not by what means the three closely allied forms distinguished their own kind ; (c) Whether morsitans and swynnertoni would readily produce hybrid offspring, and if so, what proportion of females would do so, and what proportion of hybrids would be sterile ; (d) Finally, whether interference with one species by another could be used as a measure of control. I also wanted to explore other details including markings, colouration and nature of the genitalia of the hybrids, and whether these characters were constant or variable.
Tsetse hybrids
6145W. H. Potts, Nature, 154:606-607. 1944-11-11 21:48:03.
IN 1936 I attempted to cross various species of tsetse (Glossina) with the idea that, should they hybridize readily, and should the resultant hybrids prove sterile, this might be tried as a measure of control. Corson had already, in 1932, obtained three offspring from crosses between male G. swynnertoni and female G. morsitans; he suggested, however, that these might not be true hybrids, but the result of parthenogenesis (see further details in the accompanying communication by Mr. F. L. Vanderplank). I obtained a number of offspring from this and other crosses, but as a slight doubt arose as to whether they were authentic hybrids, the results were never published.
Hybridization between Glossina Species and Suggested New Method for Control of Certain Species of Tsetse
6142F. L. Vanderplank, Nature, 154:607-608. 1944-11-11 21:43:25.
Corson and Potts record crossing Glossina swynnertoni Aust. with G. morsitans Westwood. Corson crossed twelve female G. morsitans with male G. swynnertoni, of which only two females produced a total of three pupæ. All his females lived long enough for reproduction to take place. He records the offspring, all females, as being identical with pure-bred G. morsitans, and suggested parthenogenesis. Potts crossed both male G. morsitans with female G. swynnertoni and male G. swynnertoni with female G. morsitans (see accompanying communication by Mr. W. H. Potts).
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