Heritable genome editing in C. elegans via a CRISPR-Cas9 system

Experimental evolution of an RNA virus in Caenorhabditis elegans

The discovery of Orsay virus (OrV), the first virus infecting wild populations of Caenorhabditis elegans, has boosted studies of viral immunity pathways in this nematode. Considering the many advantages that C. elegans offers for fundamental research in host-pathogen interactions, this pathosystem has high potential to become a model system for experimental virus evolution studies. However, the evolutionary constraints - i.e, the balance between genetic variation, selection, drift and historical contingency- operating in this pathosystem have barely been explored. Here we describe for the first time an evolution experiment of two different OrV strains in C. elegans. Comparison of the two ancestral strains showed differences in infectivity and sequence, and highlighted the importance of consistently normalize viral inocula for meaningful comparisons among strains. After 10 serial passages of evolution, we report slight changes in infectivity and non-synonymous mutations fixed in the evolved viral populations. In addition, we observed numerous minor variants emerging in the viral population. These minor variants were not randomly distributed along the genome but concentrated in polymorphic genomic regions. Overall, our work established the grounds for future experimental virus evolution studies using Caenorhabditis nematodes.

Tackling hepatitis B Virus with CRISPR/Cas9: advances, challenges, and delivery strategies

Hepatitis B virus (HBV) infection remains a significant global health challenge, with chronic HBV leading to severe liver diseases, including cirrhosis and hepatocellular carcinoma. Current treatments often fail to eradicate the virus, highlighting the need for innovative therapeutic strategies. The CRISPR/Cas9 system has emerged as a dynamic tool for precise genome editing and presents a promising approach to targeting and eliminating HBV infection. This review provides a comprehensive overview of the advances, challenges, and delivery strategies associated with CRISPR/Cas9-based therapies for HBV. We begin by elucidating the mechanism of the CRISPR/Cas9 system and then explore HBV pathogenesis, focusing on the role of covalently closed circular DNA (cccDNA) and integrated HBV DNA in maintaining chronic infection. CRISPR/Cas9 can disrupt these key viral reservoirs, which are critical for persistent HBV replication and associated liver damage. The application of CRISPR/Cas9 in HBV treatment faces significant challenges, such as off-target effects, delivery efficiency, and immune responses. These challenges are addressed by examining current approaches to enhance the specificity, safety, and efficacy of CRISPR/Cas9. A future perspective on the development and clinical translation of CRISPR/Cas9 therapies for HBV is provided, emphasizing the requirement for further research to improve delivery methods and ensure durable safety and effectiveness. This review underscores the transformative potential of CRISPR/Cas9 in combating HBV and sets the stage for future breakthroughs in the field.

Silencing of a NRDE-3 transgene in C. elegans germ cells and early embryos is mediated by the RNAi pathway

Transgenes are highly susceptible to gene silencing in the C. elegans germline. Here, we examine the expression of the nuclear Argonaute protein NRDE-3 , comparing two GFP::NRDE-3 strains, one constructed by bombardment and one by CRISPR. We found that the GFP::NRDE-3 strain constructed by bombardment displays transgene silencing in germline and early embryos and that NRDE-3 expression can be restored in a rde-3 mutant, which disrupts the RNAi pathway. This finding reveals that NRDE-3 is not a soma-specific Argonaute protein and is, in fact, expressed in the proximal germline and early embryos.

An effective Caenorhabditis elegans CRISPR training module for high school and undergraduate summer research experiences in molecular biology

Engaging in research experiences as a high school or undergraduate student interested in science, technology, engineering, and mathematics (STEM) is pivotal for their academic and professional development. A structured teaching framework can help cultivate a student's curiosity and passion for learning and research. In this study, an eight-week training program was created to encompass fundamental molecular biology principles and hands-on laboratory activities. This curriculum focuses on using clustered regularly interspaced short palindromic repeats (CRISPR) gene editing in the Caenorhabditis elegans model organism. Through pre- and post-program assessments, enhancements in students' molecular biology proficiency and enthusiasm for scientific exploration were observed. Overall, this training module demonstrated its accessibility and ability to engage inexperienced students in molecular biology and gene editing methodologies.

Vacuolar H+-ATPase determines daughter cell fates through asymmetric segregation of the nucleosome remodeling and deacetylase complex

Asymmetric cell divisions (ACDs) generate two daughter cells with identical genetic information but distinct cell fates through epigenetic mechanisms. However, the process of partitioning different epigenetic information into daughter cells remains unclear. Here, we demonstrate that the nucleosome remodeling and deacetylase (NuRD) complex is asymmetrically segregated into the surviving daughter cell rather than the apoptotic one during ACDs in Caenorhabditis elegans. The absence of NuRD triggers apoptosis via the EGL-1-CED-9-CED-4-CED-3 pathway, while an ectopic gain of NuRD enables apoptotic daughter cells to survive. We identify the vacuolar H+-adenosine triphosphatase (V-ATPase) complex as a crucial regulator of NuRD's asymmetric segregation. V-ATPase interacts with NuRD and is asymmetrically segregated into the surviving daughter cell. Inhibition of V-ATPase disrupts cytosolic pH asymmetry and NuRD asymmetry. We suggest that asymmetric segregation of V-ATPase may cause distinct acidification levels in the two daughter cells, enabling asymmetric epigenetic inheritance that specifies their respective life-versus-death fates.

Genome editing using CRISPR, CAST, and Fanzor systems

Genetic engineering technologies are essential not only for basic science but also for generating animal models for therapeutic applications. The clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein (Cas) system, derived from adapted prokaryotic immune responses, has led to unprecedented advancements in the field of genome editing because of its ability to precisely target and edit genes in a guide RNA-dependent manner. The discovery of various types of CRISPR-Cas systems, such as CRISPR-associated transposons (CASTs), has resulted in the development of novel genome editing tools. Recently, research has expanded to systems associated with obligate mobile element guided activity (OMEGA) RNAs, including ancestral CRISPR-Cas and eukaryotic Fanzor systems, which are expected to complement the conventional CRISPR-Cas systems. In this review, we briefly introduce the features of various CRISPR-Cas systems and their application in diverse animal models.

A cytidine deaminase regulates axon regeneration by modulating the functions of the Caenorhabditis elegans HGF/plasminogen family protein SVH-1

The pathway for axon regeneration in Caenorhabditis elegans is activated by SVH-1, a growth factor belonging to the HGF/plasminogen family. SVH-1 is a dual-function factor that acts as an HGF-like growth factor to promote axon regeneration and as a protease to regulate early development. It is important to understand how SVH-1 is converted from a protease to a growth factor for axon regeneration. In this study, we demonstrate that cytidine deaminase (CDD) SVH-17/CDD-2 plays a role in the functional conversion of SVH-1. We find that the codon exchange of His-755 to Tyr in the Asp-His-Ser catalytic triad of SVH-1 can suppress the cdd-2 defect in axon regeneration. Furthermore, the stem hairpin structure around the His-755 site in svh-1 mRNA is required for the activation of axon regeneration by SVH-1. These results suggest that CDD-2 promotes axon regeneration by transforming the function of SVH-1 from a protease to a growth factor through modification of svh-1 mRNA.

Polarized localization of kinesin-1 and RIC-7 drives axonal mitochondria anterograde transport

Mitochondria transport is crucial for axonal mitochondria distribution and is mediated by kinesin-1-based anterograde and dynein-based retrograde motor complexes. While Miro and Milton/TRAK were identified as key adaptors between mitochondria and kinesin-1, recent studies suggest the presence of additional mechanisms. In C. elegans, ric-7 is the only single gene described so far, other than kinesin-1, that is absolutely required for axonal mitochondria localization. Using CRISPR engineering in C. elegans, we find that Miro is important but is not essential for anterograde traffic, whereas it is required for retrograde traffic. Both the endogenous RIC-7 and kinesin-1 act at the leading end to transport mitochondria anterogradely. RIC-7 binding to mitochondria requires its N-terminal domain and partially relies on MIRO-1, whereas RIC-7 accumulation at the leading end depends on its disordered region, kinesin-1, and metaxin2. We conclude that transport complexes containing kinesin-1 and RIC-7 polarize at the leading edge of mitochondria and are required for anterograde axonal transport in C. elegans.

GhTKPR1_8 functions to inhibit anther dehiscence and reduce pollen viability in cotton

Sporopollenin, as the main component of the pollen exine, is a highly resistant polymer that provides structural integrity under unfavourable environmental conditions. Tetraketone α-pyrone reductase 1 (TKPR1) is essential for sporopollenin formation, catalyzing the reduction of tetraketone carbonyl to hydroxylated α-pyrone. The functional role of TKPR1 in male sterility has been reported in flowering plants such as maize, rice, and Arabidopsis. However, the molecular cloning and functional characterization of TKPR1 in cotton remain unaddressed. In this study, we identified 68 TKPR1s from four cotton species, categorized into three clades. Transcriptomics and RT-qPCR demonstrated that GhTKPR1_8 exhibited typical expression patterns in the tetrad stage of the anther. GhTKPR1_8 was localized to the endoplasmic reticulum. Moreover, ABORTED MICROSPORES (GhAMS) transcriptionally activated GhTKPR1_8 as indicated by luciferase complementation tests. GhTKPR1_8-knockdown inhibited anther dehiscence and reduced pollen viability in cotton. Additionally, overexpression of GhTKPR1_8 in the attkpr1 mutant restored its male sterile phenotype. This study offers novel insights into the investigation of TKPR1 in cotton while providing genetic resources for studying male sterility.

Engineering megabase-sized genomic deletions with MACHETE (Molecular Alteration of Chromosomes with Engineered Tandem Elements)

The elimination of large genomic regions has been enabled by the advent of site-specific nucleases. However, as the intended deletions get larger, the efficiency of successful engineering decreases to a point where it is not feasible to retrieve edited cells due to the rarity of on-target events. To address this issue, we developed a system called molecular alteration of chromosomes with engineered tandem elements (MACHETE). MACHETE is a CRISPR-Cas9-based system involving two stages: the initial insertion of a bicistronic positive/negative selection cassette to the locus of interest. This is followed by the introduction of single-guide RNAs flanking the knockin cassette to engineer the intended deletion, where only cells that have lost the locus survive the negative selection. In contrast to other approaches optimizing the activity of sequence-specific nucleases, MACHETE selects for the deletion event itself, thus greatly enriching for cells with the engineered alteration. The procedure routinely takes 4-6 weeks from design to selection of polyclonal populations bearing the deletion of interest. We have successfully deployed MACHETE to engineer deletions of up to 45 Mb, as well as the rapid creation of allelic series to map the relevant activities within a locus. This protocol details the design and step-by-step procedure to engineer megabase-sized deletions in cells of interest, with potential application for cancer genetics, transcriptional regulation, genome architecture and beyond.

Phasic/tonic glial GABA differentially transduce for olfactory adaptation and neuronal aging

Phasic (fast) and tonic (sustained) inhibition of γ-aminobutyric acid (GABA) are fundamental for regulating day-to-day activities, neuronal excitability, and plasticity. However, the mechanisms and physiological functions of glial GABA transductions remain poorly understood. Here, we report that the AMsh glia in Caenorhabditis elegans exhibit both phasic and tonic GABAergic signaling, which distinctively regulate olfactory adaptation and neuronal aging. Through genetic screening, we find that GABA permeates through bestrophin-9/-13/-14 anion channels from AMsh glia, which primarily activate the metabolic GABAB receptor GBB-1 in the neighboring ASH sensory neurons. This tonic action of glial GABA regulates the age-associated changes of ASH neurons and olfactory responses via a conserved signaling pathway, inducing neuroprotection. In addition, the calcium-evoked, vesicular glial GABA release acts upon the ionotropic GABAA receptor LGC-38 in ASH neurons to regulate olfactory adaptation. These findings underscore the fundamental significance of glial GABA in maintaining healthy aging and neuronal stability.

The chromatin factors SET-26 and HCF-1 oppose the histone deacetylase HDA-1 in longevity and gene regulation in C. elegans

SET-26, HCF-1, and HDA-1 are highly conserved chromatin factors with key roles in development and aging. Here we present mechanistic insights into how these factors regulate gene expression and modulate longevity in C. elegans. We show that SET-26 and HCF-1 cooperate to regulate a common set of genes, and both antagonize the histone deacetylase HDA-1 to limit longevity. HCF-1 localization at chromatin is largely dependent on functional SET-26, whereas SET-26 is only minorly affected by loss of HCF-1, suggesting that SET-26 could recruit HCF-1 to chromatin. HDA-1 opposes SET-26 and HCF-1 on the regulation of a subset of their common target genes and in longevity. Our findings suggest that SET-26, HCF-1, and HDA-1 comprise a mechanism to fine-tune gene expression and longevity and likely have important implications for the mechanistic understanding of how these factors function in diverse organisms, particularly in aging biology.

PBRM-1/PBAF-regulated genes in a multipotent progenitor in Caenorhabditis elegans

The Caenorhabditis elegans somatic gonadal precursors (SGPs) are multipotent progenitors that generate all somatic cells of the adult reproductive system. The 2 SGPs originate in the mesodermal layer and are born through a division that produces one SGP and one head mesodermal cell (hmc). One hmc terminally differentiates, and the other dies by programmed cell death. The polybromo-associated BAF (PBAF) chromatin remodeling complex promotes the multipotent SGP fate. The complete loss of PBAF causes lethality, so we used a combination of Cre/lox recombination and GFP nanobody-directed protein degradation to eliminate PBRM-1, the signature subunit of the PBAF complex, from 83 mesodermal cells, including SGPs, body muscles, and the hmc. We used RNA sequencing to identify genes acting downstream of PBAF in these cells and identified 1,955 transcripts that were significantly differentially expressed between pbrm-1(-) and pbrm-1(+) in the mesoderm of L1 larvae. We found that genes involved in muscle cell function were overrepresented; most of these genes had lower expression in the absence of PBRM-1, suggesting that PBAF promotes muscle differentiation. Among the differentially expressed genes were 125 that are normally expressed at higher levels in SGP vs hmc and positively regulated by pbrm-1 and 53 that are normally expressed at higher levels in hmc vs SGP and are negatively regulated by pbrm-1; these are candidate regulators of the SGP/hmc fate decision. We validated one candidate gene using a fluorescent reporter; the hsp-12.3 reporter was derepressed in SGPs in pbrm-1 mutants, suggesting that hsp-12.3 expression is normally repressed by pbrm-1 in SGPs.

Dual tagging of GFP and Degron on endogenous COSA-1 in Caenorhabditis elegans as a crossover investigation tool

COSA-1 is essential for accurate meiosis in C. elegans . Two null mutants ( cosa-1 ( me13 ) and cosa-1 ( tm3298 ) ) have been notably studied. These null mutants exhibit severe meiotic defects, hindering the observation of the subtle or dynamic nature of COSA-1 function. To overcome these limitations, we developed a C. elegans strain with inducible COSA-1 degradation using the Auxin-Inducible Degron (AID) system. This strain exhibits normal fertility and COSA-1::GFP foci. Auxin treatment successfully depletes COSA-1, resulting in a 96% decrease in progeny viability and 12 univalent chromosomes in diakinesis oocytes. This strain serves as a valuable tool for studying the dynamics of COSA-1.

Fused in sarcoma regulates glutamate signaling and oxidative stress response

Mutations in fused in sarcoma (fust-1) are linked to ALS. However, how these ALS causative mutations alter physiological processes and lead to the onset of ALS remains largely unknown. By obtaining humanized fust-1 ALS mutations via CRISPR-CAS9, we generated a C. elegans ALS model. Homozygous fust-1 ALS mutant and fust-1 deletion animals are viable in C. elegans. This allows us to better characterize the molecular mechanisms of fust-1-dependent responses. We found FUST-1 plays a role in regulating superoxide dismutase, glutamate signaling, and oxidative stress. FUST-1 suppresses SOD-1 and VGLUT/EAT-4 in the nervous system. FUST-1 also regulates synaptic AMPA-type glutamate receptor GLR-1. We found that fust-1 ALS mutations act as loss-of-function in SOD-1 and VGLUT/EAT-4 phenotypes, whereas the fust-1 ALS mutations act as gain-of-function in redox homeostasis and the microbe-induced oxidative stress response. We hypothesized that FUST-1 is a link between glutamate signaling and SOD-1. Our results may provide new insights into the human ALS alleles and their roles in pathological mechanisms that lead to ALS.

Applications of Innovation Technologies for Personalized Cancer Medicine: Stem Cells and Gene-Editing Tools

Personalized medicine is a new approach toward safer and even cheaper treatments with minimal side effects and toxicity. Planning a therapy based on individual properties causes an effective result in a patient's treatment, especially in a complex disease such as cancer. The benefits of personalized medicine include not only early diagnosis with high accuracy but also a more appropriate and effective therapeutic approach based on the unique clinical, genetic, and epigenetic features and biomarker profiles of a specific patient's disease. In order to achieve personalized cancer therapy, understanding cancer biology plays an important role. One of the crucial applications of personalized medicine that has gained consideration more recently due to its capability in developing disease therapy is related to the field of stem cells. We review various applications of pluripotent, somatic, and cancer stem cells in personalized medicine, including targeted cancer therapy, cancer modeling, diagnostics, and drug screening. CRISPR-Cas gene-editing technology is then discussed as a state-of-the-art biotechnological advance with substantial impacts on medical and therapeutic applications. As part of this section, the role of CRISPR-Cas genome editing in recent cancer studies is reviewed as a further example of personalized medicine application.

Lentiviral Transduction-based CRISPR/Cas9 Editing of Schistosoma mansoni Acetylcholinesterase

Background

Recent studies on CRISPR/Cas9-mediated gene editing in Schistosoma mansoni have shed new light on the study and control of this parasitic helminth. However, the gene editing efficiency in this parasite is modest.

Methods

To improve the efficiency of CRISPR/Cas9 genome editing in schistosomes, we used lentivirus, which has been effectively used for gene editing in mammalian cells, to deliver plasmid DNA encoding Cas9 nuclease, a sgRNA targeting acetylcholinesterase (SmAChE) and a mCherry fluorescence marker into schistosomes.

Results

MCherry fluorescence was observed in transduced eggs, schistosomula, and adult worms, indicating that the CRISPR components had been delivered into these parasite stages by lentivirus. In addition, clearly changed phenotypes were observed in SmAChE-edited parasites, including decreased SmAChE activity, reduced hatching ability of edited eggs, and altered behavior of miracidia hatched from edited eggs. Next-generation sequencing analysis demonstrated that the lentiviral transduction-based CRISPR/Cas9 gene modifications in SmAChE-edited schistosomes were homology-directed repair predominant but with much lower efficiency than that obtained using electroporation (data previously published by our laboratory) for the delivery of CRISPR components.

Conclusion

Taken together, electroporation is more efficient than lentiviral transduction in the delivery of CRISPR/Cas9 into schistosomes for programmed genome editing. The exploration of tactics for enhancing CRISPR/Cas9 gene editing provides the basis for the future improvement of programmed genome editing in S. mansoni.

Distinct pathways for export of silencing RNA in Caenorhabditis elegans systemic RNAi

Dietary supplied double-stranded RNA (dsRNA) can trigger RNA interference (RNAi) systemically in some animals, including the nematode Caenorhabditis elegans. Although this phenomenon has been utilized as a major tool for gene silencing in C. elegans, how cells spread the silencing RNA throughout the organism is largely unknown. Here, we identify two novel systemic RNAi-related factors, REXD-1 and TBC-3, and show that these two factors together with SID-5 act redundantly to promote systemic spreading of dsRNA. Animals that are defective in all REXD-1, TBC-3, and SID-5 functions show strong deficiency in export of dsRNA from intestinal cells, whereas cellular uptake and processing of dsRNA and general secretion events other than dsRNA secretion are still functional in the triple mutant animals. Our findings reveal pathways that specifically regulate the export of dsRNA in parallel, implying the importance of spreading RNA molecules for intercellular communication in organisms.

MosSCI-mediated exogenous gene expression is modulated by genomic positioning

Although the Mos1-mediated single-copy insertion (MosSCI) technique has been widely used to generate stable transgenic Caenorhabditis elegans strains, the link between stability of expression and integration site still needs to be explored. Here, experimental evidence is provided that transgenes are not able to match the level of transcription of their native counterpart, and that insertions at certain locations can result in an external stress-mediated increase in expression. Insertion site ttTi5605 on chromosome II was shown to be a superior location, at least when introducing reproduction related genes. Thus, this study provides a reference for the selection of an optimal site for MosSCI which provides acceptable expression performance whilst minimizing undesirable secondary effects.

Mechanisms of nuclear pore complex disassembly by the mitotic Polo-like kinase 1 (PLK-1) in C. elegans embryos

The nuclear envelope, which protects and organizes the genome, is dismantled during mitosis. In the Caenorhabditis elegans zygote, nuclear envelope breakdown (NEBD) of the parental pronuclei is spatially and temporally regulated during mitosis to promote the unification of the maternal and paternal genomes. Nuclear pore complex (NPC) disassembly is a decisive step of NEBD, essential for nuclear permeabilization. By combining live imaging, biochemistry, and phosphoproteomics, we show that NPC disassembly is a stepwise process that involves Polo-like kinase 1 (PLK-1)-dependent and -independent steps. PLK-1 targets multiple NPC subcomplexes, including the cytoplasmic filaments, central channel, and inner ring. PLK-1 is recruited to and phosphorylates intrinsically disordered regions (IDRs) of several multivalent linker nucleoporins. Notably, although the phosphosites are not conserved between human and C. elegans nucleoporins, they are located in IDRs in both species. Our results suggest that targeting IDRs of multivalent linker nucleoporins is an evolutionarily conserved driver of NPC disassembly during mitosis.

Targeting miRNA by CRISPR/Cas in cancer: advantages and challenges

Clustered regulatory interspaced short palindromic repeats (CRISPR) has changed biomedical research and provided entirely new models to analyze every aspect of biomedical sciences during the last decade. In the study of cancer, the CRISPR/CRISPR-associated protein (Cas) system opens new avenues into issues that were once unknown in our knowledge of the noncoding genome, tumor heterogeneity, and precision medicines. CRISPR/Cas-based gene-editing technology now allows for the precise and permanent targeting of mutations and provides an opportunity to target small non-coding RNAs such as microRNAs (miRNAs). However, the development of effective and safe cancer gene editing therapy is highly dependent on proper design to be innocuous to normal cells and prevent introducing other abnormalities. This study aims to highlight the cutting-edge approaches in cancer-gene editing therapy based on the CRISPR/Cas technology to target miRNAs in cancer therapy. Furthermore, we highlight the potential challenges in CRISPR/Cas-mediated miRNA gene editing and offer advanced strategies to overcome them.

Synthetic biology in multicellular organisms: Opportunities in nematodes

Synthetic biology has mainly focused on introducing new or altered functionality in single cell systems: primarily bacteria, yeast, or mammalian cells. Here, we describe the extension of synthetic biology to nematodes, in particular the well-studied model organism Caenorhabditis elegans, as a convenient platform for developing applications in a multicellular setting. We review transgenesis techniques for nematodes, as well as the application of synthetic biology principles to construct nematode gene switches and genetic devices to control motility. Finally, we discuss potential applications of engineered nematodes.

Polarized localization of kinesin-1 and RIC-7 drives axonal mitochondria anterograde transport

Mitochondria transport is crucial for mitochondria distribution in axons and is mediated by kinesin-1-based anterograde and dynein-based retrograde motor complexes. While Miro and Milton/TRAK were identified as key adaptors between mitochondria and kinesin-1, recent studies suggest the presence of additional mechanisms. In C. elegans, ric-7 is the only single gene described so far, other than kinesin-1, that is absolutely required for axonal mitochondria localization. Using CRISPR engineering in C. elegans, we find that Miro is important but is not essential for anterograde traffic, whereas it is required for retrograde traffic. Both the endogenous RIC-7 and kinesin-1 act at the leading end to transport mitochondria anterogradely. RIC-7 recruitment to mitochondria requires its N-terminal domain and partially relies on MIRO-1, whereas RIC-7 accumulation at the leading end depends on its disordered region, kinesin-1 and metaxin2. We conclude that polarized transport complexes containing kinesin-1 and RIC-7 form at the leading edge of mitochondria, and that these complexes are required for anterograde axonal transport.

Point-of-Care Testing for Infectious Diseases Based on Class 2 CRISPR/Cas Technology

The early detection of infectious diseases and microorganisms is critical for effective disease treatment, control, and prevention. Currently, nucleic acid testing and antigen-antibody serum reaction are the two methods most commonly used for the detection of infectious diseases. The former is highly accurate, specific, and sensitive, but it is time-consuming, expensive, and has special technician and instrument requirements. The latter is rapid and economical, but it may not be accurate and sensitive enough. Therefore, it is necessary to develop a quick and on-site diagnostic test for point-of-care testing (POCT) to enable the clinical detection of infectious diseases that is accurate, sensitive, convenient, cheap, and portable. Here, CRISPR/Cas-based detection methods are detailed and discussed in depth. The powerful capacity of these methods will facilitate the development of diagnostic tools for POCT, though they still have some limitations. This review explores and highlights POCT based on the class 2 CRISPR/Cas assay, such as Cas12 and Cas13 proteins, for the detection of infectious diseases. We also provide an outlook on perspectives, multi-application scenarios, clinical applications, and limitations for POCT based on class 2 CRISPR/Cas technology.

An endomembrane zinc transporter negatively regulates systemic RNAi in Caenorhabditis elegans

Double-stranded RNA (dsRNA) regulates gene expression in a sequence-dependent manner. In Caenorhabditis elegans, dsRNA spreads through the body and leads to systemic RNA silencing. Although several genes involved in systemic RNAi have been genetically identified, molecules that mediate systemic RNAi remain largely unknown. Here, we identified ZIPT-9, a C. elegans homolog of ZIP9/SLC39A9, as a broad-spectrum negative regulator of systemic RNAi. We showed that RSD-3, SID-3, and SID-5 genetically act in parallel for efficient RNAi, and that zipt-9 mutants suppress the RNAi defects of all the mutants. Analysis of a complete set of deletion mutants for SLC30 and SLC39 family genes revealed that only zipt-9 mutants showed altered RNAi activity. Based on these results and our analysis using transgenic Zn2+ reporters, we propose that ZIPT-9-dependent Zn2+ homeostasis, rather than overall cytosolic Zn2+, modulates systemic RNAi activity. Our findings reveal a previously unknown function of zinc transporters in negative RNAi regulation.

Systematic characterization of small RNAs associated with C. elegans Argonautes

Argonaute proteins generally play regulatory roles by forming complexes with the corresponding small RNAs (sRNAs). An expanded Argonaute family with 20 potentially functional members has been identified in Caenorhabditis elegans. Canonical sRNAs in C. elegans are miRNAs, small interfering RNAs including 22G-RNAs and 26G-RNAs, and 21U-RNAs, which are C. elegans piRNAs. Previous studies have only covered some of these Argonautes for their sRNA partners, and thus, a systematic study is needed to reveal the comprehensive regulatory networks formed by C. elegans Argonautes and their associated sRNAs. We obtained in situ knockin (KI) strains of all C. elegans Argonautes with fusion tags by CRISPR/Cas9 technology. RNA immunoprecipitation against these endogenously expressed Argonautes and high-throughput sequencing acquired the sRNA profiles of individual Argonautes. The sRNA partners for each Argonaute were then analyzed. We found that there were 10 Argonautes enriched miRNAs, 17 Argonautes bound to 22G-RNAs, 8 Argonautes bound to 26G-RNAs, and 1 Argonaute PRG-1 bound to piRNAs. Uridylated 22G-RNAs were bound by four Argonautes HRDE-1, WAGO-4, CSR-1, and PPW-2. We found that all four Argonautes played a role in transgenerational epigenetic inheritance. Regulatory roles of the corresponding Argonaute-sRNA complex in managing levels of long transcripts and interspecies regulation were also demonstrated. In this study, we portrayed the sRNAs bound to each functional Argonaute in C. elegans. Bioinformatics analyses together with experimental investigations provided perceptions in the overall view of the regulatory network formed by C. elegans Argonautes and sRNAs. The sRNA profiles bound to individual Argonautes reported here will be valuable resources for further studies.

FLInt: single shot safe harbor transgene integration via Fluorescent Landmark Interference

The stable incorporation of transgenes and recombinant DNA material into the host genome is a bottleneck in many bioengineering applications. Due to the low efficiency, identifying the transgenic animals is often a needle in the haystack. Thus, optimal conditions require efficient screening procedures, but also known and safe landing sites that do not interfere with host expression, low input material and strong expression from the new locus. Here, we leverage an existing library of ≈300 different loci coding for fluorescent markers that are distributed over all 6 chromosomes in Caenorhabditis elegans as safe harbors for versatile transgene integration sites using CRISPR/Cas9. We demonstrated that a single crRNA was sufficient for cleavage of the target region and integration of the transgene of interest, which can be easily followed by loss of the fluorescent marker. The same loci can also be used for extrachromosomal landing sites and as co-CRISPR markers without affecting body morphology or animal behavior. Thus, our method overcomes the uncertainty of transgene location during random mutagenesis, facilitates easy screening through fluorescence interference and can be used as co-CRISPR markers without further influence in phenotypes.

High-fidelity encoding of mechanostimuli by tactile food-sensing neurons requires an ensemble of ion channels

The nematode C. elegans uses mechanosensitive neurons to detect bacteria, which are food for worms. These neurons release dopamine to suppress foraging and promote dwelling. Through a screen of genes highly expressed in dopaminergic food-sensing neurons, we identify a K2P-family potassium channel-TWK-2-that damps their activity. Strikingly, loss of TWK-2 restores mechanosensation to neurons lacking the NOMPC-like channel transient receptor potential 4 (TRP-4), which was thought to be the primary mechanoreceptor for tactile food sensing. The alternate mechanoreceptor mechanism uncovered by TWK-2 mutation requires three Deg/ENaC channel subunits: ASIC-1, DEL-3, and UNC-8. Analysis of cell-physiological responses to mechanostimuli indicates that TRP and Deg/ENaC channels work together to set the range of analog encoding of stimulus intensity and to improve signal-to-noise characteristics and temporal fidelity of food-sensing neurons. We conclude that a specialized mechanosensory modality-tactile food sensing-emerges from coordination of distinct force-sensing mechanisms housed in one type of sensory neuron.

The chromatin factors SET-26 and HCF-1 oppose the histone deacetylase HDA-1 in longevity and gene regulation in C. elegans

SET-26, HCF-1, and HDA-1 are highly conserved chromatin factors with key roles in development and aging. Here we present mechanistic insights into how these factors regulate gene expression and modulate longevity in C. elegans. We show that SET-26 and HCF-1 cooperate to regulate a common set of genes, and both antagonize the histone deacetylase HDA-1 to limit longevity. We propose a model in which SET-26 recruits HCF-1 to chromatin in somatic cells, where they stabilize each other at the promoters of a subset of genes, particularly mitochondrial function genes, and regulate their expression. HDA-1 opposes SET-26 and HCF-1 on the regulation of a subset of their common target genes and in longevity. Our findings suggest that SET-26, HCF-1, and HDA-1 comprise a mechanism to fine-tune gene expression and longevity and likely have important implications for the mechanistic understanding of how these factors function in diverse organisms, particularly in aging biology.

Targeting endogenous proteins for spatial and temporal knockdown using auxin-inducible degron in Caenorhabditis elegans

The auxin-inducible degron (AID) provides reversible, spatiotemporal control for the knockdown of target proteins. Here, we present a protocol for AID-mediated protein knockdown in Caenorhabditis elegans. We describe steps for generating the knock-in mutants using two CRISPR-Cas9 genome editing techniques and preparing the auxin-containing nematode growth media (NGM) plates. We also detail AID-mediated spatiotemporal protein knockdown. For complete details on the use and execution of this protocol, please refer to Kurashina et al. (2021).1.

Mechanisms of Nuclear Pore Complex disassembly by the mitotic Polo-Like Kinase 1 (PLK-1) in C. elegans embryos

The nuclear envelope, which protects and organizes the interphase genome, is dismantled during mitosis. In the C. elegans zygote, nuclear envelope breakdown (NEBD) of the parental pronuclei is spatially and temporally regulated during mitosis to promote the unification of the parental genomes. During NEBD, Nuclear Pore Complex (NPC) disassembly is critical for rupturing the nuclear permeability barrier and removing the NPCs from the membranes near the centrosomes and between the juxtaposed pronuclei. By combining live imaging, biochemistry, and phosphoproteomics, we characterized NPC disassembly and unveiled the exact role of the mitotic kinase PLK-1 in this process. We show that PLK-1 disassembles the NPC by targeting multiple NPC sub-complexes, including the cytoplasmic filaments, the central channel, and the inner ring. Notably, PLK-1 is recruited to and phosphorylates intrinsically disordered regions of several multivalent linker nucleoporins, a mechanism that appears to be an evolutionarily conserved driver of NPC disassembly during mitosis. (149/150 words).

One-Sentence Summary

PLK-1 targets intrinsically disordered regions of multiple multivalent nucleoporins to dismantle the nuclear pore complexes in the C. elegans zygote.

Nematode homologs of the sour taste receptor Otopetrin1 are evolutionarily conserved acid-sensitive proton channels

Numerous taste receptors and related molecules have been identified in vertebrates and invertebrates. Otopetrin1 has recently been identified as mammalian sour taste receptor which is essential for acid sensation. However, whether other Otopetrin proteins are involved in PH-sensing remains unknown. In C. elegans, there are eight otopetrin homologous genes but their expression patterns and functions have not been reported so far. Through heterologous expression in HEK293T cells, we found that ceOTOP1a can be activated by acid in NMDG⁺ solution without conventional cations, which generated inward currents and can be blocked by zinc ions. Moreover, we found that Otopetrin channels are widely expressed in numerous tissues, especially in sensory neurons in the nematode. These results suggest that the biophysical characteristics of the Otopetrin channels in nematodes are generally conserved. However, a series of single gene mutations of otopetrins, which were constructed by CRISPR-Cas9 method, did not affect either calcium responses in ASH polymodal sensory neurons to acid stimulation or acid avoidance behaviors, suggesting that Otopetrin channels might have diverse functions among species. This study reveals that nematode Otopetrins are evolutionarily conserved acid-sensitive proton channels, and provides a framework for further revealing the function and mechanisms of Otopetrin channels in both invertebrates and vertebrates.

CRISPR interference for sequence-specific regulation of fibroblast growth factor receptor A in Schistosoma mansoni

Employing the flatworm parasite Schistosoma mansoni as a model, we report the first application of CRISPR interference (CRISPRi) in parasitic helminths for loss-of-function studies targeting the SmfgfrA gene which encodes the stem cell marker, fibroblast growth factor receptor A (FGFRA). SmFGFRA is essential for maintaining schistosome stem cells and critical in the schistosome-host interplay. The SmfgfrA gene was targeted in S. mansoni adult worms, eggs and schistosomula using a catalytically dead Cas9 (dCas9) fused to a transcriptional repressor KRAB. We showed that SmfgfrA repression resulted in considerable phenotypic differences in the modulated parasites compared with controls, including reduced levels of SmfgfrA transcription and decreased protein expression of SmFGFRA, a decline in EdU (thymidine analog 5-ethynyl-2'-deoxyuridine, which specifically stains schistosome stem cells) signal, and an increase in cell apoptosis. Notably, reduced SmfgfrA transcription was evident in miracidia hatched from SmfgfrA-repressed eggs, and resulted in a significant change in miracidial behavior, indicative of a durable repression effect caused by CRISPRi. Intravenous injection of mice with SmfgfrA-repressed eggs resulted in granulomas that were markedly reduced in size and a decline in the level of serum IgE, emphasizing the importance of SmFGFRA in regulating the host immune response induced during schistosome infection. Our findings show the feasibility of applying CRISPRi for effective, targeted transcriptional repression in schistosomes, and provide the basis for employing CRISPRi to selectively perturb gene expression in parasitic helminths on a genome-wide scale.

Visualizing Phagocytic Cargo In Vivo from Engulfment to Resolution in Caenorhabditis elegans

The nematode Caenorhabditis elegans offers many experimental advantages to study conserved mechanisms of phagocytosis and phagocytic clearance. These include the stereotyped timing of phagocytic events in vivo for time-lapse imaging, the availability of transgenic reporters labeling molecules involved in different steps of phagocytosis, and the transparency of the animal for fluorescence imaging. Further, the ease of forward and reverse genetics in C. elegans has enabled many of the initial discoveries of proteins involved in phagocytic clearance. In this chapter, we focus on phagocytosis by the large undifferentiated blastomeres of C. elegans embryos, which engulf and eliminate diverse phagocytic cargo from the corpse of the second polar body to cytokinetic midbody remnants. We describe the use of fluorescent time-lapse imaging to observe the distinct steps of phagocytic clearance and methods to normalize this process to distinguish defects in mutant strains. These approaches have enabled us to reveal new insights from the initial signaling to induce phagocytosis up until the final resolution of phagocytic cargo in phagolysosomes.

GABA signaling triggered by TMC-1/Tmc delays neuronal aging by inhibiting the PKC pathway in C. elegans

Aging causes functional decline and degeneration of neurons and is a major risk factor of neurodegenerative diseases. To investigate the molecular mechanisms underlying neuronal aging, we developed a new pipeline for neuronal proteomic profiling in young and aged animals. While the overall translational machinery is down-regulated, certain proteins increase expressions upon aging. Among these aging-up-regulated proteins, the conserved channel protein TMC-1/Tmc has an anti-aging function in all neurons tested, and the neuroprotective function of TMC-1 occurs by regulating GABA signaling. Moreover, our results show that metabotropic GABA receptors and G protein GOA-1/Goα are required for the anti-neuronal aging functions of TMC-1 and GABA, and the activation of GABA receptors prevents neuronal aging by inhibiting the PLCβ-PKC pathway. Last, we show that the TMC-1-GABA-PKC signaling axis suppresses neuronal functional decline caused by a pathogenic form of human Tau protein. Together, our findings reveal the neuroprotective function of the TMC-1-GABA-PKC signaling axis in aging and disease conditions.

A role for worm cutl-24 in background- and parent-of-origin-dependent ER stress resistance

BACKGROUND

Organisms in the wild can acquire disease- and stress-resistance traits that outstrip the programs endogenous to humans. Finding the molecular basis of such natural resistance characters is a key goal of evolutionary genetics. Standard statistical-genetic methods toward this end can perform poorly in organismal systems that lack high rates of meiotic recombination, like Caenorhabditis worms.

RESULTS

Here we discovered unique ER stress resistance in a wild Kenyan C. elegans isolate, which in inter-strain crosses was passed by hermaphrodite mothers to hybrid offspring. We developed an unbiased version of the reciprocal hemizygosity test, RH-seq, to explore the genetics of this parent-of-origin-dependent phenotype. Among top-scoring gene candidates from a partial-coverage RH-seq screen, we focused on the neuronally-expressed, cuticlin-like gene cutl-24 for validation. In gene-disruption and controlled crossing experiments, we found that cutl-24 was required in Kenyan hermaphrodite mothers for ER stress tolerance in their inter-strain hybrid offspring; cutl-24 was also a contributor to the trait in purebred backgrounds.

CONCLUSIONS

These data establish the Kenyan strain allele of cutl-24 as a determinant of a natural stress-resistant state, and they set a precedent for the dissection of natural trait diversity in invertebrate animals without the need for a panel of meiotic recombinants.

A Decade of CRISPR-Cas Gnome Editing in C. elegans

CRISPR-Cas allows us to introduce desired genome editing, including mutations, epitopes, and deletions, with unprecedented efficiency. The development of CRISPR-Cas has progressed to such an extent that it is now applicable in various fields, with the help of model organisms. C. elegans is one of the pioneering animals in which numerous CRISPR-Cas strategies have been rapidly established over the past decade. Ironically, the emergence of numerous methods makes the choice of the correct method difficult. Choosing an appropriate selection or screening approach is the first step in planning a genome modification. This report summarizes the key features and applications of CRISPR-Cas methods using C. elegans, illustrating key strategies. Our overview of significant advances in CRISPR-Cas will help readers understand the current advances in genome editing and navigate various methods of CRISPR-Cas genome editing.

In vivo labeling of endogenous genomic loci in C. elegans using CRISPR/dCas9

Visualization of genomic loci with open chromatin state has been reported in mammalian tissue culture cells using a CRISPR/Cas9-based system that utilizes an EGFP-tagged endonuclease-deficient Cas9 protein (dCas9::EGFP) (Chen et al. 2013). Here, we adapted this approach for use in Caenorhabditis elegans . We generated a C. elegans strain that expresses the dCas9 protein fused to two nuclear-localized EGFP molecules (dCas9::NLS::2xEGFP::NLS) in an inducible manner. Using this strain, we report the visualization in live C. elegans embryos of two endogenous repetitive loci, rrn-4 and rrn-1 , from which 5S and 18S ribosomal RNAs are constitutively generated.

New Therapeutics for Extracellular Vesicles: Delivering CRISPR for Cancer Treatment

Cancers are defined by genetic defects, which underlines the prospect of using gene therapy in patient care. During the past decade, CRISPR technology has rapidly evolved into a powerful gene editing tool with high fidelity and precision. However, one of the impediments slowing down the clinical translation of CRISPR-based gene therapy concerns the lack of ideal delivery vectors. Extracellular vesicles (EVs) are nano-sized membrane sacs naturally released from nearly all types of cells. Although EVs are secreted for bio-information conveyance among cells or tissues, they have been recognized as superior vectors for drug or gene delivery. Recently, emerging evidence has spotlighted EVs in CRISPR delivery towards cancer treatment. In this review, we briefly introduce the biology and function of the CRISPR system and follow this with a summary of current delivery methods for CRISPR applications. We emphasize the recent progress in EV-mediated CRISPR editing for various cancer types and target genes. The reported strategies for constructing EV-CRISPR vectors, as well as their limitations, are discussed in detail. The review aims to throw light on the clinical potential of engineered EVs and encourage the expansion of our available toolkit to defeat cancer.

Highly efficient transgenesis with miniMos in Caenorhabditis briggsae

Caenorhabditis briggsae as a companion species for Caenorhabditis elegans has played an increasingly important role in study of evolution of development and genome and gene regulation. Aided by the isolation of its sister spices, it has recently been established as a model for speciation study. To take full advantage of the species for comparative study, an effective transgenesis method especially those with single-copy insertion is important for functional comparison. Here, we improved a transposon-based transgenesis methodology that had been originally developed in C. elegans but worked marginally in C. briggsae. By incorporation of a heat shock step, the transgenesis efficiency in C. briggsae with a single-copy insertion is comparable to that in C. elegans. We used the method to generate 54 independent insertions mostly consisting of a mCherry tag over the C. briggsae genome. We demonstrated the use of the tags in identifying interacting loci responsible for hybrid male sterility between C. briggsae and Caenorhabditis nigoni when combined with the GFP tags we generated previously. Finally, we demonstrated that C. briggsae tolerates the C. elegans toxin, PEEL-1, but not SUP-35, making the latter a potential negative selection marker against extrachromosomal array.

Regulation of aging by balancing mitochondrial function and antioxidant levels

Aging is the deterioration of physiological mechanisms that is associated with getting old. There is a link between aging and mitochondrial function. However, there is an unresolved relationship between ATP levels and aging. To address this issue, we administered febuxostat (FBX), an inhibitor of human xanthine oxidase (XO)/xanthine dehydrogenase (XDH), to C. elegans. We used C. elegans as a model to evaluate the effects of FBX and to challenge the enigma of the relationship between ATP and lifespan. In this study, we showed that FBX protects mitochondria and prevents age-related muscle deterioration in C. elegans. In addition, we showed that FBX administration could increase ATP levels without overloading the mitochondria while extending the lifespan. We also showed that the combination of FBX and an antioxidant as a protection against ROS prolongs lifespan more. We have shown that the antioxidant effects and increased ATP levels may lead to antiaging effects.

Integration of CRISPR/Cas9 with artificial intelligence for improved cancer therapeutics

Gene editing has great potential in treating diseases caused by well-characterized molecular alterations. The introduction of clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)–based gene-editing tools has substantially improved the precision and efficiency of gene editing. The CRISPR/Cas9 system offers several advantages over the existing gene-editing approaches, such as its ability to target practically any genomic sequence, enabling the rapid development and deployment of novel CRISPR-mediated knock-out/knock-in methods. CRISPR/Cas9 has been widely used to develop cancer models, validate essential genes as druggable targets, study drug-resistance mechanisms, explore gene non-coding areas, and develop biomarkers. CRISPR gene editing can create more-effective chimeric antigen receptor (CAR)-T cells that are durable, cost-effective, and more readily available. However, further research is needed to define the CRISPR/Cas9 system’s pros and cons, establish best practices, and determine social and ethical implications. This review summarizes recent CRISPR/Cas9 developments, particularly in cancer research and immunotherapy, and the potential of CRISPR/Cas9-based screening in developing cancer precision medicine and engineering models for targeted cancer therapy, highlighting the existing challenges and future directions. Lastly, we highlight the role of artificial intelligence in refining the CRISPR system's on-target and off-target effects, a critical factor for the broader application in cancer therapeutics.

Channel-independent function of UNC-9/Innexin in spatial arrangement of GABAergic synapses in C. elegans

Precise synaptic connection of neurons with their targets is essential for the proper functioning of the nervous system. A plethora of signaling pathways act in concert to mediate the precise spatial arrangement of synaptic connections. Here we show a novel role for a gap junction protein in controlling tiled synaptic arrangement in the GABAergic motor neurons in Caenorhabditis elegans, in which their axons and synapses overlap minimally with their neighboring neurons within the same class. We found that while EGL-20/Wnt controls axonal tiling, their presynaptic tiling is mediated by a gap junction protein UNC-9/Innexin, that is localized at the presynaptic tiling border between neighboring dorsal D-type GABAergic motor neurons. Strikingly, the gap junction channel activity of UNC-9 is dispensable for its function in controlling tiled presynaptic patterning. While gap junctions are crucial for the proper functioning of the nervous system as channels, our finding uncovered the novel channel-independent role of UNC-9 in synapse patterning.

CRISPR-Cas9 Technology for the Creation of Biological Avatars Capable of Modeling and Treating Pathologies: From Discovery to the Latest Improvements

This is a spectacular moment for genetics to evolve in genome editing, which encompasses the precise alteration of the cellular DNA sequences within various species. One of the most fascinating genome-editing technologies currently available is Clustered Regularly Interspaced Palindromic Repeats (CRISPR) and its associated protein 9 (CRISPR-Cas9), which have integrated deeply into the research field within a short period due to its effectiveness. It became a standard tool utilized in a broad spectrum of biological and therapeutic applications. Furthermore, reliable disease models are required to improve the quality of healthcare. CRISPR-Cas9 has the potential to diversify our knowledge in genetics by generating cellular models, which can mimic various human diseases to better understand the disease consequences and develop new treatments. Precision in genome editing offered by CRISPR-Cas9 is now paving the way for gene therapy to expand in clinical trials to treat several genetic diseases in a wide range of species. This review article will discuss genome-editing tools: CRISPR-Cas9, Zinc Finger Nucleases (ZFNs), and Transcription Activator-Like Effector Nucleases (TALENs). It will also encompass the importance of CRISPR-Cas9 technology in generating cellular disease models for novel therapeutics, its applications in gene therapy, and challenges with novel strategies to enhance its specificity.

Expanded FLP toolbox for spatiotemporal protein degradation and transcriptomic profiling in Caenorhabditis elegans

Control of gene expression in specific tissues and/or at certain stages of development allows the study and manipulation of gene function with high precision. Site-specific genome recombination by the flippase (FLP) and cyclization recombination (Cre) enzymes has proved particularly relevant. Joint efforts of many research groups have led to the creation of efficient FLP and Cre drivers to regulate gene expression in a variety of tissues in Caenorhabditis elegans. Here, we extend this toolkit by the addition of FLP lines that drive recombination specifically in distal tip cells, the somatic gonad, coelomocytes, and the epithelial P lineage. In some cases, recombination-mediated gene knockouts do not completely deplete protein levels due to persistence of long-lived proteins. To overcome this, we developed a spatiotemporally regulated degradation system for green fluorescent fusion proteins based on FLP-mediated recombination. Using 2 stable nuclear pore proteins, MEL-28/ELYS and NPP-2/NUP85 as examples, we report the benefit of combining tissue-specific gene knockout and protein degradation to achieve complete protein depletion. We also demonstrate that FLP-mediated recombination can be utilized to identify transcriptomes in a C. elegans tissue of interest. We have adapted RNA polymerase DamID for the FLP toolbox and by focusing on a well-characterized tissue, the hypodermis, we show that the vast majority of genes identified by RNA polymerase DamID are known to be expressed in this tissue. These tools allow combining FLP activity for simultaneous gene inactivation and transcriptomic profiling, thus enabling the inquiry of gene function in various complex biological processes.

Forward genetic screening identifies novel roles for N-terminal acetyltransferase C and histone deacetylase in C. elegans development

Coordinating the balance between development and stress responses is critical for organismal survival. However, the cellular signaling controlling this mechanism is not well understood. In Caenorhabditis elegans, it has been hypothesized that a genetic network regulated by NIPI-3/Tibbles may control the balance between animal development and immune response. Using a nipi-3(0) lethality suppressor screen in C. elegans, we reveal a novel role for N-terminal acetyltransferase C complex natc-1/2/3 and histone deacetylase hda-4, in the control of animal development. These signaling proteins act, at least in part, through a PMK-1 p38 MAP kinase pathway (TIR-1-NSY-1-SEK-1-PMK-1), which plays a critical role in the innate immunity against infection. Additionally, using a transcriptional reporter of SEK-1, a signaling molecule within this p38 MAP kinase system that acts directly downstream of C/EBP bZip transcription factor CEBP-1, we find unexpected positive control of sek-1 transcription by SEK-1 along with several other p38 MAP kinase pathway components. Together, these data demonstrate a role for NIPI-3 regulators in animal development, operating, at least in part through a PMK-1 p38 MAPK pathway. Because the C. elegans p38 MAP kinase pathway is well known for its role in cellular stress responses, the novel biological components and mechanisms pertaining to development identified here may also contribute to the balance between stress response and development.

PEZO-1 and TRP-4 mechanosensors are involved in mating behavior in Caenorhabditis elegans

Male mating in Caenorhabditis elegans is a complex behavior with a strong mechanosensory component. C. elegans has several characterized mechanotransducer proteins, but few have been shown to contribute to mating. Here, we investigated the roles of PEZO-1, a piezo channel, and TRP-4, a mechanotransducing TRPN channel, in male mating behavior. We show that pezo-1 is expressed in several male-specific neurons with known roles in mating. We show that, among other neurons, trp-4 is expressed in the Post-Cloacal sensilla neuron type A (PCA) sensory neuron, which monitors relative sliding between the male and the hermaphrodite and inhibits neurons involved in vulva detection. Mutations in both genes compromise many steps of mating, including initial response to the hermaphrodite, scanning, turning, and vulva detection. We performed pan-neuronal imaging during mating between freely moving mutant males and hermaphrodites. Both pezo-1 and trp-4 mutants showed spurious activation of the sensory neurons involved in vulva detection. In trp-4 mutants, this spurious activation might be caused by PCA failure to inhibit vulva-detecting neurons during scanning. Indeed, we show that without functional TRP-4, PCA fails to detect the relative sliding between the male and hermaphrodite. Cell-specific TRP-4 expression restores PCA's mechanosensory function. Our results demonstrate new roles for both PEZO-1 and TRP-4 mechanotransducers in C. elegans mating behavior.

Advances in CRISPR/Cas9

CRISPR/Cas9 technology has become the most examined gene editing technology in recent years due to its simple design, yet low cost, high efficiency, and simple operation, which can also achieve simultaneous editing of multiple loci. It can also be carried out without using plasmids, saving lots of troubles caused by plasmids. CRISPR/Cas9 has shown great potential in the study of genes or genomic functions in microorganisms, plants, animals, and human beings. In this review, we will examine the history, structure, and basic mechanisms of the CRISPR/Cas9 system, describe its great value in precision medicine and sgRNA library screening, and dig its great potential in a new field: DNA information storage.