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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Predicting the spread and persistence of genetically modified dominant sterile male mosquitoes

18680
A. Ickowicz, S. D. Foster, G. R. Hosack and K. R. Hayes,  Parasites and Vectors,  14:480. 2021-09-16 13:03:47.
Reproductive containment provides an opportunity to implement a staged-release strategy for genetic control of malaria vectors, in particular allowing predictions about the spread and persistence of (self-limiting) sterile and male-biased strains to be compared to outcomes before moving to (self-sustaining) gene-drive strains. In this study, we: (i) describe a diffusion–advection–reaction model of the spread and persistence of a single cohort of male mosquitoes; (ii) elicit informative prior distributions for model parameters, for wild-type (WT) and genetically modified dominant sterile strains (DSM); (iii) estimate posterior distributions for WT strains using data from published mark-recapture-release (MRR) experiments, with inference performed through the Delayed-Rejection Adaptive Metropolis algorithm; and (iv) weight prior distributions, in order to make predictions about genetically modified strains using Bayes factors calculated for the WT strains. If a single cohort of 5000 genetically modified dominant sterile male mosquitoes are released at the same location as previous MRR experiments with their WT counterparts, there is a 90% probability that the expected number of released mosquitoes will fall to < 1 in 10 days, and that by 12 days there will be a 99% probability that no mosquitoes will be found more than 150 m from the release location. Spread and persistence models should form a key component of risk assessments of novel genetic control strategies for malaria vectors. Our predictions, used in an independent risk assessment, suggest that genetically modified sterile male mosquitoes will remain within the locality of the release site, and that they will persist for a very limited amount of time. Data gathered following the release of these mosquitoes will enable us to test the accuracy of these predictions and also provide a means to update parameter distributions for genetic strains in a coherent (Bayesian) framework. We anticipate this will provide additional insights about how to conduct probabilistic risk assessments of stage-released genetically modified mosquitoes.

Novel Sterile Insect Technology Program Results in Suppression of a Field Mosquito Population and Subsequently to Reduced Incidence of Dengue

30892
Lisiane de Castro Poncio, Filipe Apolinário dos Anjos, Deborah A de Oliveira, Débora Rebechi, et al.,  The Journal of Infectious Diseases,  224:1005-1014. 2021-09-15 08:29:17.
There is a steady rise in the global incidence of Aedes-borne arbovirus disease. It has become urgent to develop alternative solutions for mosquito vector control. We developed a new method of sterilization of male mosquitoes with the goal to suppress a local Aedes aegypti population and to prevent the spread of dengue. Sterile male mosquitoes were produced from a locally acquired Ae. aegypti colony by using a treatment that includes double-stranded RNA and thiotepa. A field study was conducted with sterile mosquito releases being performed on a weekly basis in predefined areas. There were 2 intervention periods (INT1 and INT2), with treatment and control areas reversed between INT1 and INT2. During INT1, releases in the treated area resulted in up to 91.4% reduction of live progeny of field Ae. aegypti mosquitoes recorded over time, while the control neighborhoods (no releases of sterile male mosquitoes) remained highly infested. The successful implementations of the program during INT1 and INT2 were associated with 15.9-fold and 13.7-fold lower incidences of dengue in the treated area compared to the control areas, respectively. Our data show the success of this new sterile insect technology-based program in preventing the spread of dengue.

Evolutionary robustness of killer meiotic drives

18676
P. G. Madgwick and J. B. Wolf,  Evolution Letters,  2021-09-12 12:53:08.
A meiotic driver is a selfish genetic element that interferes with the process of meiosis to promote its own transmission. The most common mechanism of interference is gamete killing, where the meiotic driver kills gametes that do not contain it. A killer meiotic driver is predicted to spread rapidly through a population at the expense of other genes in the rest of the genome. The rapid spread of a killer meiotic driver is expected to be chased by the rapid spread of a suppressor that returns fair meiosis. Paradoxically, while this might imply that meiotic drivers should be evolutionarily transient, numerous ancient killer meiotic drivers have been discovered that have persisted for millions of years. To understand the rationale that could potentially explain such evolutionary robustness, we explore different possible mechanisms of killer meiotic drive and the different possible associated mechanisms of suppression. We use a framework that considers how the different stages of meiosis result in different structured interactions among cells with different genotypes in various combinations. Across possible interactions, we show that there are three genotypically distinct drive mechanisms that create alternative selective conditions for the spread of different types of suppressors. We show that killer meiotic drivers are more evolutionarily robust if they operate among sister cells (after meiosis I and before meiosis II) than at any other point during meiosis. The different drive mechanisms we identify make testable predictions that could explain why some killer meiotic drivers are transient while others are ancient.

Suppressing mosquito populations with precision guided sterile males

18513
M. Li, T. Yang, M. Bui, S. Gamez, T. Wise, N. P. Kandul, J. Liu, L. Alcantara, H. Lee, J. R. Edula, R. Raban, Y. Zhan, Y. Wang, N. DeBeaubien, J. Chen, H. M. Sánchez C, J. B. Bennett, I. Antoshechkin, C. Montell, J. M. Marshall and O. S. Akbari,  Nature Communications,  12:5374. 2021-09-10 14:42:45.
The mosquito Aedes aegypti is the principal vector for arboviruses including dengue/yellow fever, chikungunya, and Zika virus, infecting hundreds of millions of people annually. Unfortunately, traditional control methodologies are insufficient, so innovative control methods are needed. To complement existing measures, here we develop a molecular genetic control system termed precision-guided sterile insect technique (pgSIT) in Aedes aegypti. PgSIT uses a simple CRISPR-based approach to generate flightless females and sterile males that are deployable at any life stage. Supported by mathematical models, we empirically demonstrate that released pgSIT males can compete, suppress, and even eliminate mosquito populations. This platform technology could be used in the field, and adapted to many vectors, for controlling wild populations to curtail disease in a safe, confinable, and reversible manner.

Two newly introduced Wolbachia endosymbionts induce cell host differences in competitiveness and metabolic responses

18510
T. P. Li, S. S. Zha, C. Y. Zhou, X. Xia, A. A. Hoffmann and X. Y. Hong,  Appl Environ Microbiol,  Aem0147921. 2021-09-09 14:34:33.
Wolbachia endosymbionts can induce multiple reproductive manipulations in their hosts, with cytoplasmic incompatibility (CI) being one of the most common manipulations. The important agricultural pests, white-backed planthopper (Sogatella furcifera) and brown planthopper (Nilaparvata lugens), are usually infected with CI-inducing Wolbachia wFur and non-CI-inducing Wolbachia wLug, respectively. The biological effects of these infections when present in a host cell are unknown. Here, we introduced the two Wolbachia strains into an Aedes albopictus cell line to stably establish a wFur-infected cell line (WFI) and a wLug-infected cell line (WLI). In a mixed culture, WFI cells were completely replaced by WLI cells, pointing to a stronger competitiveness of the WLI cell line. We found that infection by both Wolbachia strains reduced cell growth rates, but WLI had a faster cell growth rate than WFI, and this difference in cell growth rate combined with possible Wolbachia differences in diffusivity may have affected cell competitiveness. By examining gene expression and metabolites in the two lines, we found that some genes and key metabolites responded to differences in cell competitiveness. These results point to potential mechanisms that could contribute to the relative performance of hosts infected by these strains and also highlight the substantial impact of a non-CI Wolbachia on metabolism, which may in turn influence fitness of its native host. IMPORTANCE Wolbachia transinfection in insects can be used to suppress pests and block virus transmission. We stably introduced two Wolbachia strains from rice planthoppers into cell lines of an important arbovirus mosquito vector, Aedes albopictus. The competitiveness of host cells from the lines infected by the two Wolbachia strains was different, as were metabolic responses of the cell lines. These results suggest potential metabolic effects of Wolbachia on native hosts which could be exploited when they are transinfected into novel hosts for pest control.

A supernumerary “B-sex” chromosome drives male sex determination in the Pachón cavefish, Astyanax mexicanus

18508
B. Imarazene, K. Du, S. Beille, E. Jouanno, R. Feron, Q. Pan, J. Torres-Paz, C. Lopez-Roques, A. Castinel, L. Gil, C. Kuchly, C. Donnadieu, H. Parrinello, L. Journot, C. Cabau, M. Zahm, C. Klopp, T. Pavlica, A. Al-Rikabi, T. Liehr, S. A. Simanovsky, J. Bo,  Current Biology,  2021-09-09 14:28:39.
Sex chromosomes are generally derived from a pair of classical type-A chromosomes, and relatively few alternative models have been proposed up to now.(1)(,)(2) B chromosomes (Bs) are supernumerary and dispensable chromosomes with non-Mendelian inheritance found in many plant and animal species(3)(,)(4) that have often been considered as selfish genetic elements that behave as genome parasites.(5)(,)(6) The observation that in some species Bs can be either restricted or predominant in one sex(7-14) raised the interesting hypothesis that Bs could play a role in sex determination.(15) The characterization of putative B master sex-determining (MSD) genes, however, has not yet been provided to support this hypothesis. Here, in Astyanax mexicanus cavefish originating from Pachón cave, we show that Bs are strongly male predominant. Based on a high-quality genome assembly of a B-carrying male, we characterized the Pachón cavefish B sequence and found that it contains two duplicated loci of the putative MSD gene growth differentiation factor 6b (gdf6b). Supporting its role as an MSD gene, we found that the Pachón cavefish gdf6b gene is expressed specifically in differentiating male gonads, and that its knockout induces male-to-female sex reversal in B-carrying males. This demonstrates that gdf6b is necessary for triggering male sex determination in Pachón cavefish. Altogether these results bring multiple and independent lines of evidence supporting the conclusion that the Pachón cavefish B is a "B-sex" chromosome that contains duplicated copies of the gdf6b gene, which can promote male sex determination in this species.

Persistent Spodoptera frugiperda rhabdovirus infection in Sf9 cells is not restricted by Wolbachia wMelPop-CLA and wAlbB strains and is targeted by the RNAi machinery

18362
R. Parry, H. de Malmanche and S. Asgari,  Virology,  563:82-87. 2021-09-08 14:28:58.
The endosymbiotic bacterium Wolbachia pipientis confers RNA virus refractoriness in Drosophila and Aedes mosquitoes. Questions remain about the Wolbachia-virus restriction phenotype and how extensive this phenomenon may be within other arthropods. Here, we generated two Spodoptera frugiperda cell lines stably transinfected with two strains of Wolbachia, wAlbB and wMelPop-CLA. Despite the high density of Wolbachia in stably infected Sf9 cells, RT-PCR indicated the presence of the negative-sense RNA virus Spodoptera frugiperda rhabdovirus (SfRV) in Wolbachia-infected and uninfected cell lines. No differences in the replication of SfRV between Sf9 and Wolbachia-infected cells was found. RNA-Seq analysis of the parental Sf9 cells supported SfRV's presence in these cells with abundant 20 nt virus-derived small RNAs indicating active replication of SfRV in these cells. Overall, this study supports a growing body of evidence that Wolbachia does not restrict negative-sense RNA viruses and generates an in vitro model to examine Lepidoptera-Wolbachia virus interactions.

Wolbachia-Conferred Antiviral Protection Is Determined by Developmental Temperature

18357
E. Chrostek, N. Martins, M. S. Marialva and L. Teixeira,  mBio,  e0292320. 2021-09-08 14:13:12.
Overall, we show that Wolbachia-conferred antiviral protection is temperature dependent, being present or absent depending on the environmental conditions. This interaction likely impacts Wolbachia-host interactions in nature and, as a result, frequencies of host and symbionts in different climates. Dependence of Wolbachia-mediated pathogen blocking on developmental temperature could be used to dissect the mechanistic bases of protection and influence the deployment of Wolbachia to prevent transmission of arboviruses. IMPORTANCE Insects are often infected with beneficial intracellular bacteria. The bacterium Wolbachia is extremely common in insects and can protect them from pathogenic viruses. This effect is being used to prevent transmission of dengue and Zika viruses by Wolbachia-infected mosquitoes. To understand the biology of insects in the wild, we need to discover which factors affect Wolbachia-conferred antiviral protection. Here, we show that the temperature at which insects develop from eggs to adults can determine the presence or absence of antiviral protection. The environment, therefore, strongly influences this insect-bacterium interaction. Our work may help to provide insights into the mechanism of viral blocking by Wolbachia, deepen our understanding of the geographical distribution of host and symbiont, and incentivize further research on the temperature dependence of Wolbachia-conferred protection for control of mosquito-borne disease.

Diverse wMel variants of Wolbachia pipientis differentially rescue fertility and cytological defects of the bag of marbles partial loss of function mutation in Drosophila melanogaster

18817
J. E. Bubnell, P. Fernandez-Begne, C. K. S. Ulbing and C. F. Aquadro,  G3 Genes|Genomes|Genetics,  2021-09-07 15:29:22.
In Drosophila melanogaster, the maternally inherited endosymbiont Wolbachia pipientis interacts with germline stem cell genes during oogenesis. One such gene, bag of marbles (bam) is the key switch for differentiation and also shows signals of adaptive evolution for protein diversification. These observations have led us to hypothesize that W. pipientis could be driving the adaptive evolution of bam for control of oogenesis. To test this hypothesis, we must understand the specificity of the genetic interaction between bam and W. pipientis. Previously, we documented that the W. pipientis variant, wMel, rescued the fertility of the bamBW hypomorphic mutant as a transheterozygote over a bam null. However, bamBW was generated more than 20 years ago in an uncontrolled genetic background and maintained over a balancer chromosome. Consequently, the chromosome carrying bamBW accumulated mutations that have prevented controlled experiments to further assess the interaction. Here, we used CRISPR/Cas9 to engineer the same single amino acid bam hypomorphic mutation (bamL255F) and a new bam null disruption mutation into the w1118 isogenic background. We assess the fertility of wildtype bam, bamL255F/bamnull hypomorphic, and bamL255F/bamL255F mutant females, each infected individually with 10 W. pipientis wMel variants representing three phylogenetic clades. Overall, we find that all of the W. pipientis variants tested here rescue bam hypomorphic fertility defects with wMelCS-like variants exhibiting the strongest rescue effects. In addition, these variants did not increase wildtype bam female fertility. Therefore, both bam and W. pipientis interact in genotype-specific ways to modulate female fertility, a critical fitness phenotype.

Assessment of fitness and vector competence of a New Caledonia wMel Aedes aegypti strain before field-release

18360
N. Pocquet, O. O’Connor, H. A. Flores, J. Tutagata, M. Pol, D. J. Hooker, C. Inizan, S. Russet, J. M. Duyvestyn, E. C. Pacidônio, D. Girault, D. da Silva Gonçalves, M. Minier, F. Touzain, E. Chalus, K. Lucien, F. Cheilan, T. Derycke, S. Laumond, C. P. Sim,  PLOS Neglected Tropical Diseases,  15:e0009752. 2021-09-07 14:13:26.
Dengue represents a risk for almost half of the world’s population, especially throughout the tropics. In New Caledonia, dengue outbreaks have become more frequent in the past decade along with the recent circulation of chikungunya and Zika viruses. The opportunity to use the biocontrol method involving the release of Wolbachia-infected Ae. aegypti mosquitoes has been investigated as an alternative solution to the traditional control methods, like elimination of larval habitats and pyrethroid insecticide application to kill adults, which are becoming insufficient. A local strain of Ae. aegypti carrying Wolbachia (NC-wMel) has been generated and tested to evaluate its pathogen blocking capacity for the four dengue virus serotypes as well as chikungunya and Zika viruses. The fitness of NC-wMel strain has also been assessed to estimate its ability to compete with the wild-type strain in the field. Noumea city, where a third of the population of New Caledonia resides, has been chosen as the first site to implement the method in New Caledonia. As Ae. aegypti is the only proven vector in New Caledonia, we expect a significant impact on dengue outbreaks occurring in Noumea as soon as a high frequency of NC-wMel is established in the population.

Satellite DNA-mediated diversification of a sex-ratio meiotic drive gene family in Drosophila

18354
C. A. Muirhead and D. C. Presgraves,  Nature Ecology & Evolution,  2021-09-06 14:01:24.
Sex chromosomes are susceptible to the evolution of selfish meiotic drive elements that bias transmission and distort progeny sex ratios. Conflict between such sex-ratio drivers and the rest of the genome can trigger evolutionary arms races resulting in genetically suppressed ‘cryptic’ drive systems. The Winters cryptic sex-ratio drive system of Drosophila simulans comprises a driver, Distorter on the X (Dox) and an autosomal suppressor, Not much yang, a retroduplicate of Dox that suppresses via production of endogenous small interfering RNAs (esiRNAs). Here we report that over 22 Dox-like (Dxl) sequences originated, amplified and diversified over the ~250,000-year history of the three closely related species, D. simulans, D. mauritiana and D. sechellia. The Dxl sequences encode a rapidly evolving family of protamines. Dxl copy numbers amplified by ectopic exchange among euchromatic islands of satellite DNAs on the X chromosome and separately spawned four esiRNA-producing suppressors on the autosomes. Our results reveal the genomic consequences of evolutionary arms races and highlight complex interactions among different classes of selfish DNAs.

The viral era

18352
B. Giese,  EMBO reports,  22:e53229. 2021-09-06 13:54:36.
New biotechnologies such as gene drives and engineered viruses herald a viral era that would give humans exceptional power over any organism at the level of the genotype. In synthetic biology, orthogonality—in the sense of lack of interference—between different systems or system components is sought for new creations. Current approaches to controlling gene drives also aim for orthogonality, but at a higher level of organisms, populations and species. To keep information under control, orthogonality and reversibility have to be guaranteed before  any releases. As with chemical substances, where persistence and bioaccumulation are reasons for concern, the same should apply to genetic information released into nature

Mosquito transgenesis for malaria control

18284
S. Dong, Y. Dong, M. L. Simões and G. Dimopoulos,  Trends in Parasitology,  2021-09-02 14:42:32.
Malaria is one of the deadliest diseases. Because of the ineffectiveness of current malaria-control methods, several novel mosquito vector-based control strategies have been proposed to supplement existing control strategies. Mosquito transgenesis and gene drive have emerged as promising tools for preventing the spread of malaria by either suppressing mosquito populations by self-destructing mosquitoes or replacing mosquito populations with disease-refractory populations. Here we review the development of mosquito transgenesis and its application for malaria control, highlighting the transgenic expression of antiparasitic effector genes, inactivation of host factor genes, and manipulation of miRNAs and lncRNAs. Overall, from a malaria-control perspective, mosquito transgenesis is not envisioned as a stand-alone approach; rather, its use is proposed as a complement to existing vector-control strategies.

wMel Wolbachia genome remains stable after 7 years in Australian Aedes aegypti field populations

18281
K. R. Dainty, J. Hawkey, L. M. Judd, E. C. Pacidônio, J. M. Duyvestyn, D. S. Gonçalves, S. Y. Lin, T. B. O'Donnell, S. L. O'Neill, C. P. Simmons, K. E. Holt and H. A. Flores,  Microbial Genomics,  7. 2021-09-02 14:23:53.
Infection of wMel Wolbachia in Aedes aegypti imparts two signature features that enable its application for biocontrol of dengue. First, the susceptibility of mosquitoes to viruses such as dengue and Zika is reduced. Second, a reproductive manipulation is caused that enables wMel introgression into wild-type mosquito populations. The long-term success of this method relies, in part, on evolution of the wMel genome not compromising the critical features that make it an attractive biocontrol tool. This study compared the wMel Wolbachia genome at the time of initial releases and 1-7 years post-release in Cairns, Australia. Our results show the wMel genome remains highly conserved up to 7 years post-release in gene sequence, content, synteny and structure. This work suggests the wMel genome is stable in its new mosquito host and, therefore, provides reassurance on the potential for wMel to deliver long-term public-health impacts.

Unravelling the mystery of female meiotic drive: where we are

18263
F. E. Clark and T. Akera,  Open Biol,  11:210074. 2021-09-02 13:30:18.
Female meiotic drive is the phenomenon where a selfish genetic element alters chromosome segregation during female meiosis to segregate to the egg and transmit to the next generation more frequently than Mendelian expectation. While several examples of female meiotic drive have been known for many decades, a molecular understanding of the underlying mechanisms has been elusive. Recent advances in this area in several model species prompts a comparative re-examination of these drive systems. In this review, we compare female meiotic drive of several animal and plant species, highlighting pertinent similarities.

Gene drive escape from resistance depends on mechanism and ecology

18261
F. Cook, J. J. Bull and R. Gomulkiewicz,  bioRxiv,  2021.08.30.458221. 2021-08-31 13:20:26.
Gene drives can potentially be used to suppress pest populations, and the advent of CRISPR technology has made it feasible to engineer them in many species, especially insects. What remains largely unknown for implementations is whether anti-drive resistance will evolve to block the population suppression. An especially serious threat to some kinds of drive is mutations in the CRISPR cleavage sequence that block the action of CRISPR, but designs have been proposed to avoid this type of resistance. Various types of resistance at loci away from the cleavage site remain a possibility, which is the focus here. It is known that modest-effect suppression drives can essentially `outrun' unlinked resistance even when that resistance is present from the start. We demonstrate here how the risk of evolving (unlinked) resistance can be further reduced without compromising overall suppression by introducing multiple suppression drives or by designing drives with specific ecological effects. However, we show that even modest-effect suppression drives remain vulnerable to the evolution of extreme levels of inbreeding, which halt the spread of the drive without actually interfering with its mechanism. The landscape of resistance evolution against suppression drives is therefore complex, but avenues exist for enhancing gene drive success.Competing Interest StatementThe authors have declared no competing interest.

The international governance of gene drive organisms

18320
F. Rabitz,  Environmental Politics,  2021-08-29 13:07:16.
Gene Drive Organisms (GDOs) are a proposed biotechnological intervention that might generate significant benefits for the conservation and sustainable use of biological diversity while also raising critical biosafety issues. Despite their inevitable transboundary effects, their implications for international institutions remain undertheorized. This text develops a theoretical analysis of international GDO governance. First, it elaborates the problem-structural characteristics of GDOs that turn them into a novel and distinct governance challenge, focusing on leverage, cost-benefit distributions, irreversibility, as well as uncertainty and unpredictability. Second, it derives the implications of problem structure for institutional design by focusing on pre-release risk assessment and authorization, as well as post-release monitoring and liability. Third, it uses these institutional implications for benchmarking the Cartagena Protocol on Biosafety, the focal point in international biotechnology regulation, for effective GDO governance. The text concludes that institutional reforms are required for folding GDOs into international biodiversity policy.

Flavors of Non-Random Meiotic Segregation of Autosomes and Sex Chromosomes

18819
F. Pajpach, T. Wu, L. Shearwin-Whyatt, K. Jones and F. Grützner,  Genes,  12. 2021-08-28 15:33:36.
Segregation of chromosomes is a multistep process occurring both at mitosis and meiosis to ensure that daughter cells receive a complete set of genetic information. Critical components in the chromosome segregation include centromeres, kinetochores, components of sister chromatid and homologous chromosomes cohesion, microtubule organizing centres, and spindles. Based on the cytological work in the grasshopper Brachystola, it has been accepted for decades that segregation of homologs at meiosis is fundamentally random. This ensures that alleles on chromosomes have equal chance to be transmitted to progeny. At the same time mechanisms of meiotic drive and an increasing number of other examples of non-random segregation of autosomes and sex chromosomes provide insights into the underlying mechanisms of chromosome segregation but also question the textbook dogma of random chromosome segregation. Recent advances provide a better understanding of meiotic drive as a prominent force where cellular and chromosomal changes allow autosomes to bias their segregation. Less understood are mechanisms explaining observations that autosomal heteromorphism may cause biased segregation and regulate alternating segregation of multiple sex chromosome systems or translocation heterozygotes as an extreme case of non-random segregation. We speculate that molecular and cytological mechanisms of non-random segregation might be common in these cases and that there might be a continuous transition between random and non-random segregation which may play a role in the evolution of sexually antagonistic genes and sex chromosome evolution.

Parallel pathways for recruiting effector proteins determine centromere drive and suppression

18266
T. Kumon, J. Ma, R. B. Akins, D. Stefanik, C. E. Nordgren, J. Kim, M. T. Levine and M. A. Lampson,  Cell,  2021-08-26 13:45:10.
Selfish centromere DNA sequences bias their transmission to the egg in female meiosis. Evolutionary theory suggests that centromere proteins evolve to suppress costs of this "centromere drive." In hybrid mouse models with genetically different maternal and paternal centromeres, selfish centromere DNA exploits a kinetochore pathway to recruit microtubule-destabilizing proteins that act as drive effectors. We show that such functional differences are suppressed by a parallel pathway for effector recruitment by heterochromatin, which is similar between centromeres in this system. Disrupting the kinetochore pathway with a divergent allele of CENP-C reduces functional differences between centromeres, whereas disrupting heterochromatin by CENP-B deletion amplifies the differences. Molecular evolution analyses using Murinae genomes identify adaptive evolution in proteins in both pathways. We propose that centromere proteins have recurrently evolved to minimize the kinetochore pathway, which is exploited by selfish DNA, relative to the heterochromatin pathway that equalizes centromeres, while maintaining essential functions.

Versatile Applications of the CRISPR/Cas Toolkit in Plant Pathology and Disease Management

19445
M. S. Wheatley and Y. N. Yang,  Phytopathology,  111:1080-1090. 2021-08-25 21:11:15.
New tools and advanced technologies have played key roles in facilitating basic research in plant pathology and practical approaches for disease management and crop health. Recently. the CRISPR/Cas (clustered regularly interspersed short palindromic repeats/CRISPR-associated) system has emerged as a powerful and versatile tool for genome editing and other molecular applications. This review aims to introduce and highlight the CRISPR/Cas toolkit and its current and future impact on plant pathology and disease management. We will cover the rapidly expanding horizon of various CRISPR/Cas applications in the basic study of plant-pathogen interactions, genome engineering of plant disease resistance, and molecular diagnosis of diverse pathogens. Using the citrus greening disease as an example, various CRISPR/Cas-enabled strategies are presented to precisely edit the host genome for disease resistance, to rapidly detect the pathogen for disease management, and to potentially use gene drive for insect population control. At the cutting edge of nucleic acid manipulation and detection, the CRISPR/Cas toolkit will accelerate plant breeding and reshape crop production and disease management as we face the challenges of 21st century agriculture.

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