Channel Gene Research Articles

Allele-Specific Editing of a Dominant SCN8A Epilepsy Variant Protects against Seizures and Lethality in a Murine Model.

Developmental and epileptic encephalopathies (DEEs) can result from dominant, gain of function variants of neuronal ion channels. More than 450 de novo missense variants of the sodium channel gene SCN8A have been identified in individuals with DEE. We studied a mouse model carrying the patient Scn8a variant p.Asn1768Asp. An AAV-PHP.eB virus carrying an allele-specific single guide RNA (sgRNA) was administered by intracerebroventricular injection. Cas9 was provided by an inherited transgene. Allele-specific disruption of the reading frame of the pathogenic transcript generated out-of-frame indels in 1/4 to 1/3 of transcripts throughout the brain. This editing efficiency was sufficient to rescue lethality and seizures. Neuronal hyperexcitability was reduced in cells expressing the virus. The data demonstrate efficient allele-specific editing of a dominant missense variant and support the feasibility of allele-specific therapy for DEE epilepsy. ANN NEUROL 2024;96:958-969.

Genome-Wide Identification of the Cyclic Nucleotide-Gated Ion Channel Gene Family and Expression Profiles Under Low-Temperature Stress in Luffa cylindrica L.

Cyclic nucleotide-gated ion channels (CNGCs) are cell membrane channel proteins for calcium ions. They have been reported to play important roles in survival and in the responses to environmental factors in various plants. However, little is known about the CNGC family and its functions in luffa (Luffa cylindrica L.). In this study, a bioinformatics-based method was used to identify members of the CNGC gene family in L. cylindrica. In total, 20 LcCNGCs were detected, and they were grouped into five subfamilies (I, II, Ⅲ, IV-a, and IV-b) in a phylogenetic analysis with CNGCs from Arabidopsis thaliana (20 AtCNGCs) and Momordica charantia (17 McCNGCs). The 20 LcCNGC genes were unevenly distributed on 11 of the 13 chromosomes in luffa, with none on Chromosomes 1 and 5. The members of each subfamily encoded proteins with highly conserved functional domains. An evolutionary analysis of CNGCs in luffa revealed three gene losses and a motif deletion. An examination of gene replication events during evolution indicated that two tandemly duplicated gene pairs were the primary driving force behind the evolution of the LcCNGC gene family. PlantCARE analyses of the LcCNGC promoter regions revealed various cis-regulatory elements, including those responsive to plant hormones (abscisic acid, methyl jasmonate, and salicylic acid) and abiotic stresses (light, drought, and low temperature). The presence of these cis-acting elements suggested that the encoded CNGC proteins may be involved in stress responses, as well as growth and development. Transcriptome sequencing (RNA-seq) analyses revealed tissue-specific expression patterns of LcCNGCs in various plant parts (roots, stems, leaves, flowers, and fruit) and the upregulation of some LcCNGCs under low-temperature stress. To confirm the accuracy of the RNA-seq data, 10 cold-responsive LcCNGC genes were selected for verification by quantitative real-time polymerase chain reaction (RT-qPCR) analysis. Under cold conditions, LcCNGC4 was highly upregulated (>50-fold increase in its transcript levels), and LcCNGC3, LcCNGC6, and LcCNGC13 were upregulated approximately 10-fold. Our findings provide new information about the evolution of the CNGC family in L. cylindrica and provide insights into the functions of the encoded CNGC proteins.

TMEM175 Plays a Crucial Role in Osteoblast Differentiation by Regulating Lysosomal Function and Autophagy.

Bone provides structural support, enables movement, protects internal organs, regulates calcium and phosphorus levels, and contains bone marrow essential for hematopoiesis. Osteoblasts are specialized cells responsible for bone formation through the secretion of extracellular matrix components. Transmembrane protein 175 (TMEM175), which functions as an endosomal/lysosomal K+ channel and a lysosomal H+ channel, regulates lysosomal function and autophagy. Despite the recognized importance of lysosomes and autophagy in osteoblast differentiation, the specific role of TMEM175 in osteoblast differentiation has not been revealed. In this study, we investigated whether TMEM175 is associated with human bone mineral density (BMD) and fracture, and examined the role of TMEM175 in osteoblast differentiation. In analyses of single nucleotide polymorphisms (SNPs) of pore ion channel genes using the mouse2human database, a significant correlation between TMEM175 SNPs and human BMD and fracture was identified. TMEM175 expression levels were found to increase during osteoblast differentiation from bone chip-derived mesenchymal stem cells (BMSCs). Knockdown of TMEM175 in BMSCs suppressed osteoblast differentiation, as evidenced by decreased matrix mineralization and lower expression levels of osteoblast marker genes. Further analysis indicated that TMEM175 deficiency leads to lysosomal dysfunction and partially impairs autophagic clearance during osteoblast differentiation. Moreover, the TMEM175 inhibitor 4-aminopyridine (4-AP) decreased osteoblast differentiation of BMSCs. Taken together, this study reveals that TMEM175 plays an important role for osteoblast differentiation by regulating lysosomal function and autophagic clearance.

PathVar: A Customisable NGS Variant Calling Algorithm Implicates Novel Candidate Genes and Pathways in Hemiplegic Migraine.

The exponential growth of next-generation sequencing (NGS) data requires innovative bioinformatics approaches to unravel the genetic underpinnings of diseases. Hemiplegic migraine (HM), a debilitating neurological disorder with a genetic basis, is one such condition that warrants further investigation. Notably, the genetic heterogeneity of HM is underscored by the fact that approximately two-thirds of patients lack pathogenic variants in the known causal ion channel genes. In this context, we have developed PathVar, a novel bioinformatics algorithm that harnesses publicly available tools and software for pathogenic variant discovery in NGS data. PathVar integrates a suite of tools, including HaplotypeCaller from the Genome Analysis Toolkit (GATK) for variant calling, Variant Effect Predictor (VEP) and ANNOVAR for variant annotation, and TAPES for assigning the American College of Medical Genetics and Genomics (ACMG) pathogenicity labels. Applying PathVar to whole exome sequencing data from 184 HM patients, we detected 648 variants that are probably pathogenic in multiple patients. Moreover, we have identified several candidate genes for HM, many of which cluster around the Rho GTPases pathway. Future research can leverage PathVar to generate high quality, candidate pathogenic variants, which may enhance our understanding of HM and other complex diseases.

Heterozygous expression of a Kcnt1 gain-of-function variant has differential effects on somatostatin- and parvalbumin-expressing cortical GABAergic neurons

More than 20 recurrent missense gain-of-function (GOF) mutations have been identified in the sodium-activated potassium (KNa) channel gene KCNT1 in patients with severe developmental and epileptic encephalopathies (DEEs), most of which are resistant to current therapies. Defining the neuron types most vulnerable to KCNT1 GOF will advance our understanding of disease mechanisms and provide refined targets for precision therapy efforts. Here, we assessed the effects of heterozygous expression of a Kcnt1 GOF variant (Kcnt1Y777H) on KNa currents and neuronal physiology among cortical glutamatergic and GABAergic neurons in mice, including those expressing vasoactive intestinal polypeptide (VIP), somatostatin (SST), and parvalbumin (PV), to identify and model the pathogenic mechanisms of autosomal dominant KCNT1 GOF variants in DEEs. Although the Kcnt1Y777H variant had no effects on glutamatergic or VIP neuron function, it increased subthreshold KNa currents in both SST and PV neurons but with opposite effects on neuronal output; SST neurons became hypoexcitable with a higher rheobase current and lower action potential (AP) firing frequency, whereas PV neurons became hyperexcitable with a lower rheobase current and higher AP firing frequency. Further neurophysiological and computational modeling experiments showed that the differential effects of the Kcnt1Y777H variant on SST and PV neurons are not likely due to inherent differences in these neuron types, but to an increased persistent sodium current in PV, but not SST, neurons. The Kcnt1Y777H variant also increased excitatory input onto, and chemical and electrical synaptic connectivity between, SST neurons. Together, these data suggest differential pathogenic mechanisms, both direct and compensatory, contribute to disease phenotypes, and provide a salient example of how a pathogenic ion channel variant can cause opposite functional effects in closely related neuron subtypes due to interactions with other ionic conductances.

Heterozygous expression of a Kcnt1 gain-of-function variant has differential effects on somatostatin- and parvalbumin-expressing cortical GABAergic neurons.

More than 20 recurrent missense gain-of-function (GOF) mutations have been identified in the sodium-activated potassium (KNa) channel gene KCNT1 in patients with severe developmental and epileptic encephalopathies (DEEs), most of which are resistant to current therapies. Defining the neuron types most vulnerable to KCNT1 GOF will advance our understanding of disease mechanisms and provide refined targets for precision therapy efforts. Here, we assessed the effects of heterozygous expression of a Kcnt1 GOF variant (Kcnt1Y777H) on KNa currents and neuronal physiology among cortical glutamatergic and GABAergic neurons in mice, including those expressing vasoactive intestinal polypeptide (VIP), somatostatin (SST), and parvalbumin (PV), to identify and model the pathogenic mechanisms of autosomal dominant KCNT1 GOF variants in DEEs. Although the Kcnt1Y777H variant had no effects on glutamatergic or VIP neuron function, it increased subthreshold KNa currents in both SST and PV neurons but with opposite effects on neuronal output; SST neurons became hypoexcitable with a higher rheobase current and lower action potential (AP) firing frequency, whereas PV neurons became hyperexcitable with a lower rheobase current and higher AP firing frequency. Further neurophysiological and computational modeling experiments showed that the differential effects of the Kcnt1Y777H variant on SST and PV neurons are not likely due to inherent differences in these neuron types, but to an increased persistent sodium current in PV, but not SST, neurons. The Kcnt1Y777H variant also increased excitatory input onto, and chemical and electrical synaptic connectivity between, SST neurons. Together, these data suggest differential pathogenic mechanisms, both direct and compensatory, contribute to disease phenotypes, and provide a salient example of how a pathogenic ion channel variant can cause opposite functional effects in closely related neuron subtypes due to interactions with other ionic conductances.

Chromosome-level genome of diamondback terrapin provides insight into the genetic basis of salinity adaptation.

Diamondback terrapins (Malaclemys terrapin centrata) exhibit strong environmental adaptability and live in both freshwater and saltwater. However, the genetic basis of this adaptability has not been the focus of research. In this study, we successfully constructed a ∼2.21-Gb chromosome-level genome assembly for M. t. centrata using high-coverage and high-depth genomic sequencing data generated on multiple platforms. The M. t. centrata genome contains 25 chromosomes and the scaffold N50 of ∼143.75 Mb, demonstrating high continuity and accuracy. In total, 53.82% of the genome assembly was composed of repetitive sequences, and 22435 protein-coding genes were predicted. Our phylogenetic analysis indicated that M. t. centrata was closely related to the red-eared slider turtle (Trachemys scripta elegans), with divergence approximately ∼23.6 million years ago (Mya) during the early Neogene period of the Cenozoic era. The population size of M. t. centrata decreased significantly over the past ∼14 Mya during the Cenozoic era. Comparative genomic analysis indicated that 36 gene families related to ion transport were expanded and several genes (AQP3, solute carrier subfamily, and potassium channel genes) underwent specific amino acid site mutations in the M. t. centrata genome. Changes to these ion transport-related genes may have contributed to the remarkable salinity adaptability of diamondback terrapin. The results of this study not only provide a high-quality reference genome for M. t. centrata but also elucidate the possible genetic basis for salinity adaptation in this species.

Osmoregulation and reproduction: evolutionary trends in prolactin functions from fish to mammals

The study of prolactin function evolution provides key insights into the diverse effects of this hormone in mammals, both in health and disease, which is relevant from both theoretical and practical perspectives. This article reviews both original and literature data concerning the role of prolactin and its receptors in regulating the sexual dimorphism of freshwater adaptation in the three-spined stickleback Gasterosteus aculeatus L. It is demonstrated that mRNA expression of prolactin gene 1 (one of two prolactin paralogs) and its receptor PRLRA increases in the brains of female sticklebacks only upon transitioning to freshwater. The brain and kidneys of sticklebacks, as androgen-dependent organs, exhibit sex-dependent expression of Prlra in seawater. It is suggested that sex-dependent osmoregulatory effects of prolactin are mediated through the PRLRA receptor in these organs. The PRLRB receptor, expressed in the kidneys and brains of sticklebacks regardless of sex in seawater, shows increased sensitivity to reduced salinity, suggesting a more active role in implementing sex-independent osmoregulatory functions of prolactin. Gills and intestines, as osmoregulatory organs, express the PRLRA and PRLRB receptors independent of sex in both seawater and freshwater. With freshwater adaptation, there is a concurrent increase in the expression of Prl1 in the brains of females and the expression of Atp1a1 (α1a subunit of Na+/K+-ATPase), Nhe3 (NHE3 sodium-proton antiport gene), and Ecac (epithelial calcium channel gene) in their gills. It is presumed that these gill genes are under positive control by prolactin. Exploring the potential for prolactin’s osmoregulatory function in mammals revealed that it may manifest in conditions such as pathologies accompanied by increased expression of prolactin receptor isoforms in osmoregulatory organs. One of such pathologies is cholestasis in female rats, which was associated with an increase in Prlr isoform expression and changes in activity and ratio of Na+/K+-ATPase subunits in the kidney. Thus, it is concluded that in fish, the osmoregulatory function of prolactin is sex-dependent, while in mammals, it may manifest under conditions of disrupted water-salt exchange.

Discovery of Knock-Down Resistance in the Major African Malaria Vector Anopheles funestus.

A major insecticide resistance mechanism in insect pests is knock-down resistance (kdr) caused by mutations in the voltage-gated sodium channel (Vgsc) gene. Despite being common in most malaria Anopheles vector species, kdr mutations have never been observed in Anopheles funestus, the principal malaria vector in Eastern and Southern Africa, with resistance mainly being conferred by detoxification enzymes. In a parallel study, we monitored 10 populations of An. funestus in Tanzania for insecticide resistance unexpectedly identified resistance to a banned insecticide, DDT, in the Morogoro region. Through whole-genome sequencing of 333 An. funestus samples from these populations, we found eight novel amino acid substitutions in the Vgsc gene, including the kdr variant, L976F (equivalent to L995F in An. gambiae), in tight linkage disequilibrium with another (P1842S). The mutants were found only at high frequency in one region and were accompanied by weak signatures of a selective sweep, with a significant decline between 2017 and 2023. Notably, kdr L976F was strongly associated with survivorship to exposure to DDT insecticide, while no clear association was noted with a pyrethroid insecticide (deltamethrin). The WHO prequalifies no DDT products for vector control, and the chemical is banned in Tanzania. Widespread DDT contamination and a legacy of extensive countrywide stockpiles may have selected for this mutation. Continued monitoring is necessary to understand the origin of kdr in An. funestus, and the threat posed to insecticide-based vector control in Africa.

Voltage-gated potassium channels and genetic epilepsy.

Recent advances in exome and targeted sequencing have significantly improved the aetiological diagnosis of epilepsy, revealing an increasing number of epilepsy-related pathogenic genes. As a result, the diagnosis and treatment of epilepsy have become more accessible and more traceable. Voltage-gated potassium channels (Kv) regulate electrical excitability in neuron systems. Mutate Kv channels have been implicated in epilepsy as demonstrated in case reports and researches using gene-knockout mouse models. Both gain and loss-of-function of Kv channels lead to epilepsy with similar phenotypes through different mechanisms, bringing new challenges to the diagnosis and treatment of epilepsy. Research on genetic epilepsy is progressing rapidly, with several drug candidates targeting mutated genes or channels emerging. This article provides a brief overview of the symptoms and pathogenesis of epilepsy associated with voltage-gated potassium ion channels dysfunction and highlights recent progress in treatments. Here, we reviewed case reports of gene mutations related to epilepsy in recent years and summarized the proportion of Kv genes. Our focus is on the progress in precise treatments for specific voltage-gated potassium channel genes linked to epilepsy, including KCNA1, KCNA2, KCNB1, KCNC1, KCND2, KCNQ2, KCNQ3, KCNH1, and KCNH5.

6966 A Rhythmic Life-Threatening Enigma Unveiled: KCNH2 Mutation-Associated Torsades de Points Unmasking Primary Hyperaldosteronism in Cardiological Realm

Abstract Disclosure: S. Dejprapasorn: None. N. Nopparatana: None. S. Soonthornpun: None. R. Leelawattana: None. N. Kietsiriroje: None. S. Limumpornpetch: None. T. Nilmoje: None. W. Lohawijarn: None. T. Wongsuttipakorn: None. P. Choochuen: None. P. Limumpornpetch: None. Introduction: Primary hyperaldosteronism (PA) is characterized by hypertension and hypokalemia. However, its ability to masquerade life-threatening Torsades de Pointes makes it an unusual and dismissed diagnosis, revealing the link between PA and serious arrythmia. Clinical Case A 30-year-old female experienced three episodes of palpitations, followed by syncope. Upon admission, her blood pressure was 147/87 mmHg. ECG showed prolonged QT intervals with potassium level was 2.6 mmol/L (3.5-5.0 mmol/L). Continuous cardiac monitoring captured Torsades de Pointes. Despite potassium replacement, long QT still persisted. Pathogenic variant, c.2592+1G>A, within KCNH2 was discovered. Aldosterone concentration showed 69.65 ng/dL (9.70-62.60 ng/dL) and plasma renin activity was 0.12 ng/mL/h (1.50-5.70 ng/mL/h). Aldosterone-to-renin ratio was 580. Aldosterone post 4-h saline infusion test was 31.71 ng/dL which were consistent with PA. Adrenal unenhanced CT scan identified bilateral adrenal nodules (right 1.3 cm, left 1.1 cm). After receiving a cardioverter-defibrillator and spironolactone, the patient has had no palpitations, and their potassium level has remained normal. Clinical lessons: PA rarely presents ventricular arrhythmia. KCNH2 mutation may link between long QT syndrome (LQTS) and PA arises. LQTS type 2 is attributable to KCNH2 mutations, impacting potassium channel subunits crucial for adjusting currents during sympathetic activation. This is essential for shortening the QT interval with increasing heart rate. KCNH2 mutations disrupt this process, prolonging the QT interval and heightening the risk of arrhythmias. Aldosterone synthesis relies on calcium signaling triggered by potassium currents. Adrenal cortex hosts approximately 90 potassium channels genes, including KCNJ5 and KCNH2. Mutations in gene can disrupt the calcium signaling cascade, leading to excessive aldosterone production. While KCNJ5 mutation is well-documented in PA, the potential correlation between KCNH2 mutations and a similar mechanism remains unexplored in clinical reports to date. This case highlights the importance of a thorough comprehension of genetic cause contributing to pathogenesis of PA with complex clinical presentations. Presentation: 6/1/2024

Early developmental alterations of CA1 pyramidal cells in Dravet syndrome

Dravet Syndrome (DS) is most often caused by heterozygous loss-of-function mutations in the voltage-gated sodium channel gene SCN1A (Nav1.1), resulting in severe epilepsy and neurodevelopmental impairment thought to be cause by reduced interneuron excitability. However, recent studies in mouse models suggest that interneuron dysfunction alone does not completely explain all the cellular and network impairments seen in DS. Here, we investigated the development of the intrinsic, synaptic, and network properties of CA1 pyramidal cells in a DS model prior to the appearance of overt seizures. We report that CA1 pyramidal cell development is altered by heterozygous reduction of Scn1a, and propose that this is explained by a period of reduced intrinsic excitability in early postnatal life, during which Scn1a is normally expressed in hippocampal pyramidal cells. We also use a novel ex vivo model of homeostatic plasticity to show an instability in homeostatic response during DS epileptogenesis. This study provides evidence for the early effects of Scn1a haploinsufficiency in pyramidal cells in contributing to the pathophysiology of DS.

Exploration of the potential association between newer antiseizure medications and arrhythmias: Integrating pharmacovigilance and bioinformatics evidence

IntroductionArrhythmias resulting from newer antiseizure medications (ASMs) may significantly impact the safety and quality of life of patients with epilepsy. This study investigated the potential association between new first-line or second-line ASMs and arrhythmias. MethodsPharmacovigilance analysis was conducted using data from the Food and Drug Administration Adverse Event Reporting System (FAERS) from 2004 to 2023. A disproportionality analysis was performed to compare newer ASMs with other drugs, using carbamazepine and valproate as positive controls. Newer ASMs were categorized into sodium channel (SCN) main mechanism, SCN possible mechanism, and non-SCN group. The bioinformatics analysis involved retrieving therapeutic gene targets for ASMs from the DrugBank and OMIM databases, as well as identifying arrhythmia disease targets from the GeneCards database. Additionally, enrichment analysis of gene ontology functions and KEGG pathways was conducted. ResultsA total of 3,457 cases of arrhythmias associated with newer ASMs were identified in the FAERS database. Disproportionality analysis indicates that brivaracetam (IC025 = 0.08), zonisamide (IC025 = 0.13), eslicarbazepine (IC025 = 0.39), and lacosamide (IC025 = 0.84) exhibited a positive signal for arrhythmias, with signals predominantly observed in the SCN main mechanism group. Furthermore, bioinformatics analysis revealed the involvement of adrenergic signaling in cardiac myocytes, as well as the participation of sodium channel genes in ASM-induced arrhythmias. ConclusionOur findings suggest a potential association between SCN-ASMs and arrhythmias, highlighting the importance of monitoring and evaluating the safety profiles of newer ASMs in clinical practice. Further research is necessary to elucidate the underlying mechanisms and inform patient care strategies.

Genome-wide identification, phylogeny, and pharmacological analysis of date palm cyclic nucleotide-gated ion channel (CNGC) gene family in response to fungi

Genome-wide identification, phylogeny, and pharmacological analysis of date palm cyclic nucleotide-gated ion channel (CNGC) gene family in response to fungi

Complex epilepsy phenotype associated with chromosome 2q24.2‐q24.3 deletion involving sodium channel gene cluster

Complex epilepsy phenotype associated with chromosome 2q24.2‐q24.3 deletion involving sodium channel gene cluster

Genome-Wide Identification and Expression Analysis of the Cyclic Nucleotide-Gated Channel Gene Family in Zoysia japonica under Salt Stress.

Salt stress severely inhibits plant growth. Understanding the mechanism of plant salt tolerance is highly important to improving plant salt tolerance. Previous studies have shown that nonselective cyclic nucleotide-gated ion channels (CNGCs) play an important role in plant salt tolerance. However, current research on CNGCs mainly focuses on CNGCs in glycophytic plants, and research on CNGCs in halophytes that exhibit special salt tolerance strategies is still scarce. This study used the halophilic plant Zoysia japonica, an excellent warm-season turfgrass, as the experimental material. Through bioinformatics analysis, 18 members of the CNGC family were identified in Zoysia japonica; they were designated ZjCNGC1 through ZjCNGC18 according to their scaffold-level chromosomal positions. ZjCNGCs are divided into four groups (I-IV), with the same groups having differentiated protein-conserved domains and gene structures. ZjCNGCs are unevenly distributed on 16 scaffold-level chromosomes. Compared with other species, the ZjCNGCs in Group III exhibit obvious gene expansion, mainly due to duplication of gene segments. The collinearity between ZjCNGCs, OsCNGCs, and SjCNGCs suggests that CNGCs are evolutionarily conserved among gramineous plants. However, the Group III ZjCNGCs are only partially collinear with OsCNGCs and SjCNGCs, implying that the expansion of Group III ZjCNGC genes may have been an independent event occurring in Zoysia japonica. Protein interaction prediction revealed that ZjCNGCs, calcium-dependent protein kinase, H+-ATPase, outwardly rectifying potassium channel protein, and polyubiquitin 3 interact with ZjCNGCs. Multiple stress response regulatory elements, including those involved in salt stress, are present on the ZjCNGC promoter. The qPCR results revealed differences in the expression patterns of ZjCNGCs in different parts of the plant. Under salt stress conditions, the expression of ZjCNGCs was significantly upregulated in roots and leaves, with ZjCNGC8 and ZjCNGC13 showing the greatest increase in expression in the roots. These results collectively suggest that ZjCNGCs play an important role in salt tolerance and that their expansion into Group III may be a special mechanism underlying the salt tolerance of Zoysia japonica.

Detection of mutations in the voltage-gated sodium channel gene of Varroa destructor (Acari: Varroidae) populations

The honeybee (Apis mellifera) ectoparasite, Varroa destructor, is one of the most important honeybee pests worldwide. Acaricides, including the pyrethroids (tau-fluvalinate, flumethrin), and organophosphate (coumaphos) have been applied to control this mite within apiaries, still the long-term, constant, and excessive use of these products has led to the development of resistance in many populations. Three different mutations (L925V, L925I, L925M) at position 925 and one mutation (M918L) at 918 position of the V. destructor voltage-gated sodium channel (VGSC) have been associated with the resistance to these compounds. In the present study, we examined the presence of resistance mutations in the VGSC gene, encoding the target of pyrethroids, in the V. destructor population collected from the Kayseri and Sivas provinces of Central Anatolia Region of Türkiye. A total of 200 V. destructor samples were collected from 20 apiaries in two provinces throughout 2023. To investigate the mutations in Varroa samples, the domain II region of the VGSC gene was amplified using PCR and sequenced. The nucleotide sequencing of the IIS4-IIS5 linker region of the VGSC gene revealed one amino acid change at position 925: a leucine to isoleucine substitution (L925I). No mutations at other positions were identified. Homozygous resistant alleles were detected in 20 (40 %) of the sequenced 50 samples in the study areas. However, we detected the homozygous sensitive allele (wild-type allele, L925) in the remaining samples (50/30, 60 %). The result shows that this status may indicate a problem for Varroa control in the future. Thus, alternative acaricide with a mode of action of different pyrethroids should be considered in the control of V. destructor populations in these provinces.

Widespread geographic distribution of Aedes aegypti (Diptera: Culicidae) kdr variants in Panama.

We searched for evidence of knockdown resistance (kdr) mutations in the voltage-gated sodium channel gene of Aedes aegypti (Linnaeus) (Diptera: Culicidae) and Aedes albopictus (Skuse) (Diptera: Culicidae) mosquitoes from Panama. Conventional PCR was performed on 469 Ae. aegypti and 349 Ae. albopictus. We did not discover kdr mutations in Ae. albopictus, but 2 nonsynonymous kdr mutations, V1016I (found in 101 mosquitoes) and F1534C (found in 29 of the mosquitoes with the V1016I), were detected in Ae. aegypti. These kdr mutations were present in all specimens that were successfully sequenced for both IIS5-S6 and IIIS6 regions, which included samples collected from 8 of the 10 provinces of Panama. No other kdr mutations were found in Ae. aegypti, including V1016G, which has already been reported in Panama. Findings suggest that the V1016I-F1534C variant is prevalent in Panama, which might be related to the introduction and passive movement of mosquitoes as part of the used-tire trade. However, we cannot rule out the possibility that selection on de novo replacement of kdr mutations also partially explains the widespread distribution pattern of these mutations. These 2 ecological and evolutionary processes are not mutually exclusive, though, as they can occur in tandem. Research in Panama needs to calculate the genotypic and allelic frequencies of kdr alleles in local Ae. aegypti populations and to test whether some combinations confer phenotypic resistance or not. Finally, future studies will have to track the introduction and spreading of new kdr mutations in both Aedes species.

Identification and Characterization of Shaker Potassium Channel Gene Family and Response to Salt and Chilling Stress in Rice.

Shaker potassium channel proteins are a class of voltage-gated ion channels responsible for K+ uptake and translocation, playing a crucial role in plant growth and salt tolerance. In this study, bioinformatic analysis was performed to identify the members within the Shaker gene family. Moreover, the expression patterns of rice Shaker(OsShaker) K+ channel genes were analyzed in different tissues and salt treatment by RT-qPCR. The results revealed that there were eight OsShaker K+ channel genes distributed on chromosomes 1, 2, 5, 6 and 7 in rice, and their promoters contained a variety of cis-regulatory elements, including hormone-responsive, light-responsive, and stress-responsive elements, etc. Most of the OsShaker K+ channel genes were expressed in all tissues of rice, but at different levels in different tissues. In addition, the expression of OsShaker K+ channel genes differed in the timing, organization and intensity of response to salt and chilling stress. In conclusion, our findings provide a reference for the understanding of OsShaker K+ channel genes, as well as their potential functions in response to salt and chilling stress in rice.

Molecular Detection of kdr and superkdr Mutation Sites and Analysis of the Binding Modes of Pyrethroid Insecticides with Voltage-Gated Sodium Channels in the Plant Bug Lygus pratensis (Hemiptera: Miridae).

This study identified genetic mutations linked to resistance to pyrethroid insecticides in the plant pest Lygus pratensis. The voltage-gated sodium channel (VGSC) gene was cloned, revealing two mutations (Met918Thr and Leu1014Phe) in laboratory strains and field populations from Inner Mongolia, resulting in variable pyrethroid resistance. A 3D model of LpVGSC was created using homology modeling, and pyrethroid binding patterns were analyzed via molecular docking. Molecular dynamics simulations confirmed structural stability changes and binding stability of pyrethroids to VGSC sites. Mutation frequencies of homozygous and heterozygous genotypes did not exceed 40 and 20%, respectively. Toxicity tests showed high resistance to λ-cyhalothrin (LC50:401.31 ng/cm2). The kdr (L1014F) and superkdr (M918T) mutations weakened interaction forces, reducing pyrethroid binding. M918T and L1014F mutations are predicted to reduce Type I pyrethroid affinity, suggesting Type II pyrethroids may be more effective against resistant strains. These findings aid in resistance management and insecticide design.