Lethal Gene Research Articles

Pervasive conditional selection of driver mutations and modular epistasis networks in cancer.

Cancer driver mutations often display mutual exclusion or co-occurrence, underscoring the key role of epistasis in carcinogenesis. However, estimating the magnitude of epistasis and quantifying its effect on tumor evolution remains a challenge. We develop a method (Coselens) to quantify conditional selection on the excess of nonsynonymous substitutions in cancer genes. Coselens infers the number of drivers per gene in different partitions of a cancer genomics dataset using covariance-based mutation models and determines whether coding mutations in a gene affect selection for drivers in any other gene. Using Coselens, we identify 296 conditionally selected gene pairs across 16 cancer types in the TCGA dataset. Conditional selection affects 25%-50% of driver substitutions in tumors with >2 drivers. Conditionally co-selected genes form modular networks, whose structures challenge the traditional interpretation of within-pathway mutual exclusivity and across-pathway synergy, suggesting a more complex scenario where gene-specific across-pathway epistasis shapes differentiated cancer subtypes.

Identification of polymorphism in APAF1 gene in holstein cattle

The article presents the data of DNA testing of Holstein cattle by the APAF1 gene. The structure of the Tatarstan population was studied in comparison with world experience. The aim of the study was to study the allelic polymorphism of the apoptosis peptide activating factor 1 gene (APAF1; g.C6315040T; p.Gln579Q→X), the cause of the fertility haplotype (HH1), in the domestic population of Holstein cattle of the Republic of Tatarstan. Genotyping was carried out by PCR-RFLP followed by electrophoretic separation in agarose gel in the presence of ethidium bromide. For the first time in the Republic of Tatarstan in the conditions of the Dairy farm "named Lenin” carried out the identification of cattle by the locus of APAF1 - BstC8 I, assessed the genetic equilibrium and structure of the population. As a result of gene diagnostics, two alleles and three genotypes were identified. The frequency of occurrence of alleles Q and X was 0.988 and 0.012; genotypes QQ and QX – 97.5 and 2.5%, respectively. Since homozygous XX embryos do not survive, they are never found among born animals. Chi-quad testing showed that the studied population is in genetic equilibrium according to the Hardy-Weinberg law. Our studies confirm an insignificant share of the presence of animals-carriers of the lethal allele in the population of Holstein cattle of domestic selection of the Republic of Tatarstan. In order to contain the spread of the mutant allele X of the apoptosis peptide activating factor 1 gene, it is recommended to conduct DNA testing of polymorphism of the APAF1 gene during the selection of pairs for breeding.

Highly Effective Markerless Genetic Manipulation of Streptococcus suis Using a Mutated PheS-Based Counterselectable Marker.

Streptococcus suis is an important zoonotic pathogen, however, an efficient markerless genetic manipulation system is still lacking for further physiological and pathological studies on this bacterium. Several techniques have been developed for markerless genetic manipulation of S. suis utilizing either a temperature-sensitive vector or a counterselectable markers (CSMs), however, at present, the efficiency of these techniques is not very satisfactory. In this study, we developed a strategy for markerless genetic manipulation of S. suis employing a CSM based on a conditionally lethal mutant allele of pheS, which encodes the α-subunit of phenylalanyl-tRNA synthetase (PheS). This mutant pheS, mPheS, was constructed by introducing site-directed mutations for a T261S/A315G double-substitution and a number of silent mutations to decrease its similarity with the endogenous wild type pheS gene (wtPheS). Additionally, five potentially strong promoters from S. suis were screened for their ability to drive high-level expression of mPheS, thus endowing the carrier strain with sufficient sensitivity to the phenylalanine analog p-chloro-phenylalanine (p-Cl-phe). Insertion of these P-mPheS cassettes into a vector or into the chromosomal locus via a linked erythromycin resistance gene revealed that mPheS allele driven by promoters P0530 and P1503 renders S. suis sensitive to as low as 0.01% (or 0.5 mM) of p-Cl-phe. This offers two potential CSMs for S. suis with p-Cl-phe as a counterselective agent. P1503-mPheS was revealed to be 100% efficient for counter-selection in S. suis by application in a precise gene deletion. Using P1503-mPheS as a CSM, a two-step insertion and excision strategy for markerless genetic manipulation of S. suis were developed, supplying a powerful tool for markerless genetic manipulation of S. suis.

Fighting Mosquitoes with Mosquitoes

A first-of-its-kind open-air study of genetically engineered mosquitoes has been conducted by scientists in the US. The biotechnology company Oxitec, spearheading these experiments, claims to have obtained positive results. However, much more elaborate and intricate studies are needed to establish whether these mosquitoes can suppress a wild population of mosquitoes that serve as viral carriers for chikungunya, dengue, Zika, and yellow fever. The study has been greenlit since April 2021 and is underway in the Florida Keys which are a group of tropical islands on the southern tip of Florida. Over the course of seven months, approximately 5 million genetically engineered Aedes aegypti mosquitoes were released by Oxitec and the firm has now completed the evaluation of almost all the release sites. The firm which is situated in Abingdom, United Kingdom showcased its results in a webinar on April 6th but is yet to publish. About 22,000 eggs were captured and taken back to the labs for observational hatching. Oxitec claims that all the female mosquitoes harboring the lethal gene died prior to adulthood. Nature 604, 608-609 (2022).

Abstract 2359: Identifying synergistic master regulators of pancreatic ductal adenocarcinoma tumorigenesis through CRISPR/Cas9 combinatorial genetic screens

Abstract Pancreatic ductal adenocarcinoma (PDAC) is the third-leading cause of cancer-related mortality and is highly resistant to cytotoxic, targeted, and immune therapies. Compared to other cancers, PDAC is remarkable for its relatively uniform set of DNA alterations; unfortunately, these hallmark events are not currently targetable and other mutations known to confer sensitivity to specific drugs are uncommon. Consequently, cytotoxic combinations remain the standard of care, with most patients quickly exhibiting primary or secondary chemoresistance. Previous studies have shown that transcriptional regulatory proteins can form small, highly interconnected and autoregulated modules that can initiate and maintain malignant tumor cell state, and that the Master Regulator (MR) protein they comprise represent a novel class of non-oncogene dependencies. We used the VIPER algorithm to identify MR proteins representing mechanistic regulators of the transcriptional state for 200 laser microdissected PDAC epithelial compartment samples, collected at Columbia University Irving Medical Center (CUIMC). To systematically identify synergistic pairs of MRs, we designed a combinatorial CRISPR-Cas9 screen based on the Big Papi dual SaCas9/SpCas9 system which was used to systematically target all possible pairs of the top 50 MRs identified by VIPER analysis across 6 PDAC cell lines (KP4, PATU8988S, PANC1, HPAFII, BXPC3, MIAPACA2) with three guide-RNAs per gene, thus differentiating between potentially idiosyncratic, cell line-specific and highly conserved genetic interactions. We also developed a novel nonparametric statistical method for inferring genetic interactions from this data based on the use of conditional Mann-Whitney U tests; our new analytical method significantly improved over a previously developed parametric model of synergy inference, demonstrating increased correlation between genetic interactions inferred from biological replicates of the same cell line while simultaneously prioritizing four established synthetic lethal gene pairs in the top 10 gene pairs following integration across all 6 cell lines: BCL2L1-MCL1, BCL2L1-BCL2L2, MAPK1-MAPK3, and SEC23A-SEC23B. The methods also identified 314 additional highly significant (FDR < 0.05), yet never previously reported synthetic lethal interactions that are being validated using an array-based, low-throughput screening platform. We expect that the results of this screen will help elucidate mechanisms controlling the state of PDAC tumor cells and identify potentially druggable gene pairs. Citation Format: Aaron T. Griffin, Mikko Turunen, Lorenzo Tomassoni, Kenneth P. Olive, Pasquale Laise, Andrea Califano. Identifying synergistic master regulators of pancreatic ductal adenocarcinoma tumorigenesis through CRISPR/Cas9 combinatorial genetic screens [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2359.

Abstract 5062: Identification of synthetic lethal gene interactions to discover novel cancer vulnerabilities and guide drug development

Abstract Poor treatment responses in patients and drug resistance are main challenges in the clinic which can arise due an incomplete understanding of genetic dependencies within cancers and an ill defined patient population. Identifying synthetic lethal (SL) relationships between a gene pair, where loss of either of the participating genes has no effect on cancer cells, however simultaneous disruption of both genes leads to cancer cell death, can uncover major survival mechanisms and expose vulnerabilities within cancers. In spite of advances in CRISPR or RNAi based loss of function screening it is difficult to identify these gene interactions solely by experimentation due to the vast mutational landscape of cancers, inability of cell lines to capture clinically relevant mutations, and large number of possible SL gene combinations. Furthermore, large scale CRISPR/RNAi screens are prone to false positive results, leading to erroneous identification of gene interactions. We developed a machine learning model to identify SL genetic interactions by integrating pathway, ontology, genomic, and loss of function features on all gene pairs. This included features, which have been shown to be predictive of SL pairs such as, involvement in important cancer hallmark processes or signaling pathways, co-expression profile in patient cancers, and many more. The model was trained using SL pairs from published large scale experimental screens across several cancer types, ultimately enabling the prediction of cancer agnostic SL pairs. Non-SL pairs had to be computationally defined using post-perturbation gene expression profiles due to the lack of published data annotating non-SL pairs. The model showed significant predictive performance (AUROC = 0.94, AUPRC = 0.93, Specificity = 0.91), additionally, when tested on a gold standard, biologically verified set of SL gene pairs across several cancer types, the model showed good generalizability. We leveraged the model to identify key clinically relevant SL relationships and uncover complementary mechanisms tied to pro-survival processes. By identifying SL gene interacting pairs, our platform can help gain a better understanding of dominant mechanisms driving cancers and guide the discovery of novel therapies, biomarkers, and combination therapies early on during drug development. Citation Format: Mukti Parikh, Manuel García-Quismondo, Neel S. Madhukar, Coryandar Gilvary. Identification of synthetic lethal gene interactions to discover novel cancer vulnerabilities and guide drug development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5062.

Abstract 1805: RAB10, a new target to tackle SMAD4 deficient cancers

Abstract TGFb pathway is an important signaling process that regulates the homeostasis of epithelial, stromal or immune cells. Misregulations of this pathway contribute to different pathologies such as cancer, fibrosis, nash or inflammatory diseases. SMAD4 genetic alterations, either via genomic loss or via mutations, can be found in many cancer types. SMAD4 is mutated or deleted in 10-15% of colorectal cancers and in 20-50% of pancreatic cancer. The poorer prognosis of colorectal cancers and pancreatic cancers patients harboring SMAD4 alterations makes SMAD4 deficiency interesting to harness for therapy. Anticancer opportunity created by loss of SMAD4 function/protein could be addressed by identifying synthetic lethal genes that encode for druggable proteins. CRISPR/CAS9 is a revolutionary discovery to produce gene knockout. CRISPR/CAS9 viability screen is a tool of choice to pinpoint new synthetic lethality interactions. In this work, to extend the genetic vulnerabilities of SMAD4-deficient tumors, we conducted a pooled genome-wide loss of function CRISPR/Cas9 screen in sets of 4 non-isogenic colorectal and pancreatic cancers cancer cell lines harboring wild-type and mutant SMAD4. We identified known and novel genetic alterations that make SMAD4-altered colorectal cancers & pancreatic cancers cells vulnerable. We will present the validation of the Ras-related protein Rab-10 (RAB10) as synthetic lethal gene with SMAD4 alteration. Citation Format: Christophe Marcireau, Hélène Erasimus, Vanessa Kolnik, Frederic Lacroix, Stephane D’agostino, Olivier Lemaitre, Alexandre Rohaut, Isabelle sanchez, Sukhvinder Sidhu, Gilbert Thill, Laurent Debussche, Michel Didier. RAB10, a new target to tackle SMAD4 deficient cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1805.

Contribution of transposable elements to transgenerational effects of chronic radioactive exposure of natural populations of Drosophila melanogaster living for a long time in the zone of the Chernobyl nuclear disaster

The accident at the Chernobyl Nuclear Power Plant (ChNPP) led to the negative impact of chronic radioactive contamination on populations of organisms associated with the transgenerational transmission of genome instability. When the destabilization of genome, different genetic damages occur, the accumulation of which leads to the formation of mutations, morphological anomalies, and mortality in the offspring. The mechanisms underlying the manifestation of transgenerational events in the offspring of irradiated parents are not well understood. In this study, for the first time, the features of the influence of transposable elements (TEs) on the long-term biological consequences of the ChNPP are considered. In this work, specimens of D. melanogaster obtained from natural populations in 2007 in the areas of the ChNPP with heterogeneous radioactive contamination were studied. The descendants from these populations were maintained in laboratory (inbred) conditions for 160 generations. A stable transgenerational transmission of dominant lethal mutations (DLMs) to the offspring of all studied populations was shown. The DLM frequencies strongly were correlated with the level of survival of offspring. The mean frequencies of recessive sex-linked lethal mutations varied at the level of spontaneous point mutations. The simultaneous presence of P, hobo and I elements indicates that the studied populations do not have a definite cytotype, their phenotypic status is unstable. The behavior of TEs in the genomes of offspring depends not only on parental exposure, but also on origin of population, distance to the ChNPP, and inbred conditions. The obtained results confirm the hypothesis that TEs are involved in transgenerational transmission and accumulation of mutations by the offspring of irradiated parents. The TEs pattern present in the Chernobyl genomes of D. melanogaster is a peculiar of epigenetic mechanism for the regulation of plasticity and adaptation of populations living for many generations under conditions of a technogenically caused radiation background.

Roche licenses Repare small molecule

Roche has agreed to license Repare Therapeutics’ camonsertib (also known as RP-3500) for $125 million and up to $1.2 billion in milestone payments. The small molecule is being developed to treat solid tumors on its own as well as in combination with other agents. Repare says camonsertib is the product of its CRISPR-based screening platform for identifying synthetic lethal gene pairs. The company launched in 2017 and went public in 2020.

SynLethDB 2.0: a web-based knowledge graph database on synthetic lethality for novel anticancer drug discovery.

Two genes are synthetic lethal if mutations in both genes result in impaired cell viability, while mutation of either gene does not affect the cell survival. The potential usage of synthetic lethality (SL) in anticancer therapeutics has attracted many researchers to identify synthetic lethal gene pairs. To include newly identified SLs and more related knowledge, we present a new version of the SynLethDB database to facilitate the discovery of clinically relevant SLs. We extended the first version of SynLethDB database significantly by including new SLs identified through Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) screening, a knowledge graph about human SLs, a new web interface, etc. Over 16 000 new SLs and 26 types of other relationships have been added, encompassing relationships among 14 100 genes, 53 cancers, 1898 drugs, etc. Moreover, a brand-new web interface has been developed to include modules such as SL query by disease or compound, SL partner gene set enrichment analysis and knowledge graph browsing through a dynamic graph viewer. The data can be downloaded directly from the website or through the RESTful Application Programming Interfaces (APIs). Database URL: https://synlethdb.sist.shanghaitech.edu.cn/v2.

Microbiome of Penaeus vannamei Larvae and Potential Biomarkers Associated With High and Low Survival in Shrimp Hatchery Tanks Affected by Acute Hepatopancreatic Necrosis Disease.

Acute hepatopancreatic necrosis disease (AHPND) is an emerging bacterial disease of cultured shrimp caused mainly by Vibrio parahaemolyticus, which harbors the lethal PirAB toxin genes. Although Penaeus vannamei (P. vannamei) postlarvae are susceptible to AHPND, the changes in the bacterial communities through the larval stages affected by the disease are unknown. We characterized, through high-throughput sequencing, the microbiome of P. vannamei larvae infected with AHPND-causing bacteria through the larval stages and compared the microbiome of larvae collected from high- and low-survival tanks. A total of 64 tanks from a commercial hatchery were sampled at mysis 3, postlarvae 4, postlarvae 7, and postlarvae 10 stages. PirAB toxin genes were detected by PCR and confirmed by histopathology analysis in 58 tanks. Seven from the 58 AHPND-positive tanks exhibited a survival rate higher than 60% at harvest, despite the AHPND affectation, being selected for further analysis, whereas 51 tanks exhibited survival rates lower than 60%. A random sample of 7 out of these 51 AHPND-positive tanks was also selected. Samples collected from the selected tanks were processed for the microbiome analysis. The V3–V4 hypervariable regions of the 16S ribosomal RNA (rRNA) gene of the samples collected from both the groups were sequenced. The Shannon diversity index was significantly lower at the low-survival tanks. The microbiomes were significantly different between high- and low-survival tanks at M3, PL4, PL7, but not at PL10. Differential abundance analysis determined that biomarkers associated with high and low survival in shrimp hatchery tanks affected with AHPND. The genera Bacillus, Vibrio, Yangia, Roseobacter, Tenacibaculum, Bdellovibrio, Mameliella, and Cognatishimia, among others, were enriched in the high-survival tanks. On the other hand, Gilvibacter, Marinibacterium, Spongiimonas, Catenococcus, and Sneathiella, among others, were enriched in the low-survival tanks. The results can be used to develop applications to prevent losses in shrimp hatchery tanks affected by AHPND.

Functional genomics and the future of iPSCs in disease modeling.

SummaryInduced pluripotent stem cells (iPSCs) are valuable in disease modeling because of their potential to expand and differentiate into virtually any cell type and recapitulate key aspects of human biology. Functional genomics are genome-wide studies that aim to discover genotype-phenotype relationships, thereby revealing the impact of human genetic diversity on normal and pathophysiology. In this review, we make the case that human iPSCs (hiPSCs) are a powerful tool for functional genomics, since they provide an in vitro platform for the study of population genetics. We describe cutting-edge tools and strategies now available to researchers, including multi-omics technologies, advances in hiPSC culture techniques, and innovations in drug development. Functional genomics approaches based on hiPSCs hold great promise for advancing drug discovery, disease etiology, and the impact of genetic variation on human biology.

Arabidopsis Novel Microgametophyte Defective Mutant 1 Is Required for Pollen Viability via Influencing Intine Development in Arabidopsis.

The pollen intine layer is necessary for male fertility in flowering plants. However, the mechanisms behind the developmental regulation of intine formation still remain largely unknown. Here, we identified a positive regulator, Arabidopsis novel microgametophyte defective mutant 1 (AtNMDM1), which influences male fertility by regulating intine formation. The AtNMDM1, encoding a pollen nuclei-localized protein, was highly expressed in the pollens at the late anther stages, 10–12. Both the mutations and the knock-down of AtNMDM1 resulted in pollen defects and significantly lowered the seed-setting rates. Genetic transmission analysis indicated that AtNMDM1 is a microgametophyte lethal gene. Calcofluor white staining revealed that abnormal cellulose distribution was present in the aborted pollen. Ultrastructural analyses showed that the abnormal intine rather than the exine led to pollen abortion. We further found, using transcriptome analysis, that cell wall modification was the most highly enriched gene ontology (GO) term used in the category of biological processes. Notably, two categories of genes, Arabinogalactan proteins (AGPs) and pectin methylesterases (PMEs) were greatly reduced, which were associated with pollen intine formation. In addition, we also identified another regulator, AtNMDM2, which interacted with AtNMDM1 in the pollen nuclei. Taken together, we identified a novel regulator, AtNMDM1 that affected cellulose distribution in the intine by regulating intine-related gene expression; furthermore, these results provide insights into the molecular mechanisms of pollen intine development.

Chemosterilization in Male: ‘Past And Present’ in Reproductive Biology

The effects of chemosterilizing agents on the testes and sperm production and maturation are much less understood than their effects on the ovaries and oogenesis. It was discovered that sterilising male insects with ionising radiation caused the emergence of chromosome-wide or chromatid-specific dominant lethal mutations, which led to the development of the classical male castration techniques1, 2. It was discovered in those investigations that alterations were not frequently found on spermatozoa, but that they were commonly visible in anomalies during the division of the zygote in the fertilised egg2, 3. Dominant lethal mutation in the screw-worm, Cochliomyia hominivorax, were first discussed vividly by LaChance & Riemann (1964)3 and LaChance & Crystal (1965)4, in the most classic experiments ever conducted. Detailed information on and complications related to dominant lethal mutations in insects caused by irradiation and sterilizing agents have been enumerated by LaChance (1967), who has also incorporated a detailed references containing research that dispensed this arena long before the era when chemosterilizing agents were introduced into the scientific community5.

Modeling endonuclease colicin-like bacteriocin operons as 'genetic arms' in plasmid-genome conflicts.

Plasmids are acellular propagating entities that depend on bacteria, as molecular parasites, for propagation. A 'tussle' between bacteria and plasmid ensues; bacteria for riddance of the plasmid and plasmid for persistence within a live host. Plasmid-maintenance systems such as endonuclease Colicin-Like Bacteriocins (CLBs) ensure plasmid propagation within the population; (i) the plasmid-cured cells are killed by the CLBs; (ii) damaged cells lyse and release the CLBs that eliminate the competitors, and (iii) the released plasmids invade new bacteria. Surprisingly, endonuclease CLB operons occur on bacterial genomes whose significance is unknown. Here, we study genetics, eco-evolutionary drive, and physiological relevance of genomic endonuclease CLB operons. We investigated plasmidic and genomic endonuclease CLB operons using sequence analyses from an eco-evolutionary perspective. We found 1266 genomic and plasmidic endonuclease CLB operons across 30 bacterial genera. Although 51% of the genomes harbor endonuclease CLB operons, the majority of the genomic endonuclease CLB operons lacked a functional lysis gene, suggesting the negative selection of lethal genes. The immunity gene of the endonuclease CLB operon protects the plasmid-cured host, eliminating the metabolic burden. We show mutual exclusivity of endonuclease CLB operons on genomes and plasmids. We propose an anti-addiction hypothesis for genomic endonuclease CLB operons. Using a stochastic hybrid agent-based model, we show that the endonuclease CLB operons on genomes confer an advantage to the host genome in terms of immunity to the toxin and elimination of plasmid burden. The conflict between bacterial genome and plasmids allows the emergence of 'genetic arms' such as CLB operons that regulate the ecological interplay of bacterial genomes and plasmids.

Novel Lethal Clostridial Infection in Florida Manatees (Trichechus manatus latirostris): Cause of the 2013 Unusual Mortality Event in the Indian River Lagoon

The Indian River Lagoon (IRL) on Florida’s east coast is a biologically diverse estuary and an important habitat to the threatened Florida manatee (Trichechus manatus latirostris). An unusual mortality event (UME) was declared by the Working Group on Marine Mammal Unusual Mortality Events in 2013 after a marked increase in manatee deaths in the IRL of an unknown cause. This UME followed a dramatic reduction of seagrass coverage in the IRL due to chronic non-toxic phytoplankton blooms, with a resultant ecosystem shift to mixed macroalgal dominance. At least 199 manatee deaths fitting the UME case definition were documented in and adjacent to the IRL during 2012–2019; mortality was highest in 2013, when 111 of these deaths were documented. The case definition included carcasses in good nutritional condition, with multiorgan congestion or wet lungs consistent with drowning without trauma. The gastrointestinal compartments of manatee carcasses were filled with diverse macroalga species, and the contents were notably more fluid than usual. Gross intestinal findings included blebbing to segmental thickening of the wall. Microscopic lesions were primarily intestinal, including necrosis, edema, hemorrhage, mucosa-associated lymphoid changes, and inflammation, sometimes associated with Gram-positive bacterial rods. A multidisciplinary approach of environmental and carcass sampling found no causative evidence through tests for micro- and macroalgal biotoxins, trace metals, general toxin screening, or vitreum biochemistry. Microbiological, cytological, immunohistochemical, and molecular analyses of Clostridiales from intestinal samples identified Clostridioides difficile toxin A, toxins A/B and toxin A gene; Paeniclostridium sordellii lethal gene (and other potential virulence factors from a sequenced strain); and Clostridium perfringens alpha and epsilon toxin genes. The results from this 8 year-long investigation are indicative that the cause of death in this manatee UME was associated with clostridial infection, initiated by a shift to a predominantly macroalgal diet.

Effective Management of Aedes aegypti Linn. (Diptera: Culicidae) Population through Conventional to Genetic Control and Nanotechnology Approaches: A Short Review

There are many vector–borne illnesses known to be spread by the mosquito Aedes aegypti Linn. (Diptera: Culicidae), which kills millions of people each year worldwide. There is no vaccination available for A. aegypti–transmitted viral diseases so far. As a result, it is imperative to control the mosquitoes or vector population which may helpful to avoid the dispersal and causes of certain diseases. The most common and conventional mechanism to control mosquitoes population are physical, biological, and chemical control measures that have all been used to prevent Aedes species borne disease spreading. Among these the most effective method is chemical control method but it results into the environmental pollution and causes damage to non–target individuals as well. A manipulation through self–limiting using genetic engineering among mosquitoes is an effective substitute to one sex for the control of insect pests. Using the modern concept of gene manipulation, the lethal gene through an antidote (tetracycline) was repressed among male mosquitos in vitro and subsequently released in the natural environment to mate with normal female and give rise filial generation which will die during larval stage due to lack of tetracycline. The most profound and recent use of nanotechnology to generate more effective and less dangerous repellent and larvicidal compositions is another strategy under investigation. The development of novel nanotechnology–based formulations for containing natural and synthetic repellents is an important step toward more effective systems with fewer adverse side effects.

Genetic resiliency associated with dominant lethal TPM1 mutation causing atrial septal defect with high heritability

SummaryAnalysis of large-scale human genomic data has yielded unexplained mutations known to cause severe disease in healthy individuals. Here, we report the unexpected recovery of a rare dominant lethal mutation in TPM1, a sarcomeric actin-binding protein, in eight individuals with large atrial septal defect (ASD) in a five-generation pedigree. Mice with Tpm1 mutation exhibit early embryonic lethality with disrupted myofibril assembly and no heartbeat. However, patient-induced pluripotent-stem-cell-derived cardiomyocytes show normal beating with mild myofilament defect, indicating disease suppression. A variant in TLN2, another myofilament actin-binding protein, is identified as a candidate suppressor. Mouse CRISPR knock-in (KI) of both the TLN2 and TPM1 variants rescues heart beating, with near-term fetuses exhibiting large ASD. Thus, the role of TPM1 in ASD pathogenesis unfolds with suppression of its embryonic lethality by protective TLN2 variant. These findings provide evidence that genetic resiliency can arise with genetic suppression of a deleterious mutation.

Lethal giant larvae gene is required for normal nymphal development and midgut morphogenesis in Locusta migratoria.

Disruption of morphogenesis, an essential process in organismal development, can lead to disruption of biological processes, reduction in fitness, or even death of an organism. The roles of lethal giant larvae (Lgl) protein in maintaining tissue organization have been studied extensively in mammals, but little is known about this gene's roles in promoting correct tissue morphogenesis in insects. In this study, we identified an Lgl ortholog in Locusta migratoria. RT-qPCR results revealed that LmLgl was constitutively expressed during third, fourth, and fifth instar nymphs. Furthermore, LmLgl showed highest expression in the ovary followed by wing pads, midgut, hindgut, Malpighian tubules, and foregut of the third-instar nymphs. To examine the role of LmLgl in L. migratoria development, RNA interference was performed during nymphal stages. Silencing of LmLgl increased body size but decreased bodyweight by 9.0%. Histological sections of the midgut revealed abnormal large masses of disordered epithelial cells in dsLmLgl-injected nymphs. In addition, downregulation of LmLgl transcript levels significantly altered the morphological structure in midgut, resulting in the formation of tumor-like structures. Our results indicated that LmLgl may act as a tumor-suppressor gene, which plays an essential role in maintaining a normal morphological structure in the midgut of L. migratoria. Our results also suggest that LmLgl may be explored as a potential target for developing dsRNA-based biological pesticides for managing insect pests.

Performance of Swedish Warmblood fragile foal syndrome carriers and breeding prospects

BackgroundWarmblood fragile foal syndrome (WFFS) is a monogenetic defect caused by a recessive lethal missense point mutation in the procollagen‐lysine, 2‐oxoglutarate 5‐dioxygenase 1 gene (PLOD1, c.2032G>A). The majority of homozygous WFFS horses are aborted during gestation. Clinical signs of affected horses include fragile skin, skin and mucosa lacerations, hyperextension of the articulations, and hematomas. In spite of its harmful effect, a relatively high frequency of WFFS carriers has been found in Warmblood horses, suggesting a heterozygote advantage. Thus, in this study our aims were to: (1) estimate the frequency of WFFS carriers in the Swedish Warmblood breed (SWB), (2) estimate the effect of WFFS carrier genotype on performance traits in two SWB subpopulations bred for different disciplines, and (3) simulate the potential effects of balancing selection and different selection strategies on the frequency of carriers.MethodsIn total, 2288 SWB sport horses born between 1971 and 2020 were tested for the WFFS mutation and had estimated breeding values (EBV) for ten traditional evaluating and 50 linear descriptive traits.ResultsThe frequency of WFFS carriers calculated from a pool of 511 randomly selected SWB horses born in 2017 was equal to 7.4% and ranged from 0.0 to 12.0% among the whole set of tested SWB horses, starting from 1971 till 2020. The effect of the WFFS carrier genotype was significant for several EBV mainly related to movements and dressage traits and especially for horses not bred for the show jumping discipline. Using simulation, we showed that balancing selection can maintain a recessive lethal allele in populations such as the SWB breed over generations and that the frequency is expected to slowly decrease in absence of balancing selection. Finally, we showed that selection against carrier sires can result in a more rapid decrease of the frequency of the mutant allele over time.ConclusionFurther research is needed to confirm the apparent association between equine performance and the WFFS carrier genotype. Identification of such associations or new causative mutations for horse performance traits can serve as new tools in horse breeding to select for healthy, sustainable, and better performing horses.