Phylogenetic analysis of the ATP-binding cassette proteins suggests a new ABC protein subfamily J in Aedes aegypti (Diptera: Culicidae)

MDR49 coding for both P-glycoprotein and TMOF transporter functions in ivermectin resistance, trypsin activity inhibition, and fertility in the yellow fever mosquito, Aedes aegypti

This study investigated the function of the MDR49 gene in Aedes aegypti. MDR49 mutants were constructed using CRISPR/Cas9 technology; the mutation led to increased sensitivity to ivermectin (LC50: from 1.3090 mg L-1 to 0.5904 mg L-1), and a reduction in midgut trypsin activity. These findings suggest that the P-gp encoded by MDR49 confers resistance to ivermectin and impacts the reproductive function in Ae. aegypti. RNA interference technology showed that knockdown of MDR49 gene resulted in a significant decrease in the expression of VGA1 after a blood meal, as well as a decrease in the number of eggs laid and their hatching rate. LC-MS revealed that following ivermectin treatment, the MDR493d+2s/3d+2s strain larvae exhibited significantly higher drug concentrations in the head and fat body compared to the wild type. Modeling of inward-facing P-gp and molecular docking found almost no difference in the affinity of P-gp for ivermectin before and after the mutation. However, modeling of the outward-facing conformation demonstrated that the flexible linker loop between TM5 and TM6 of P-gp undergoes changes after the mutation, resulting in a decrease in trypsin activity and an increase in sensitivity to ivermectin. These results provide useful insights into ivermectin resistance and the other roles played by the MDR49 gene.

Chaihu Shugan prevents cholesterol gallstone formation by ameliorating the microbiota dysbiosis and metabolic disturbance in mice

Introduction: Cholesterol gallstone (CGS) is a biliary tract disorder requiring treatment in approximately 20% of patients. The efficacy of Chaihu Shugan in preventing CGS recurrence after successful treatment remains uncertain. Methods: We examined the in vivo preventive efficacy of Chaihu Shugan using a CGS mouse model and used multi-omics to study the interplay between gut microbiota, metabolism, and gene expression. Results: The intestinal microbiota was severely dysregulated during the formation of CGS, showing a marked decrease in the abundance of beneficial microbiota, especially Lactobacillus and Akkermansia. Chaihu Shugan prevented CGS formation by restoring the composition of the gut microbiota and reversing the metabolic disturbances caused by dysbiosis. This preventive effect of Chaihu Shugan was paralleled by changes in the expression of metabolism-related genes in the liver. A network pharmacology analysis of Chaihu Shugan revealed that obacunone may be the key active metabolite in regulating bile acid metabolism. Multi-omics and correlation analyses elucidated the interplay between gut microbiota, metabolism, and gene alterations in the dose-dependent effect of Chaihu Shugan. Conclusion: Our data show that Chaihu Shugan can prevent CGS and indicate its mechanisms of action.

Characterization and transcriptional expression of ABCG genes in Bactrocera dorsalis: Insights into their roles in fecundity and insecticidal stress response

The ATP-binding cassette (ABC) transporters are essential for regulating various physiological processes and insecticide resistance across different living organisms. ABCG subfamily genes have diverse functions in insects, but little is known about the function of ABCGs in a serious agricultural pest, Bactrocera dorsalis. In this study, 15 BdABCG genes were identified, and BdABCG6 and BdABCG11 were highly expressed in the pupal and adult stages, especially during the transition period from pupae to adults. Silencing of these two genes resulted in a significant reduction of egg production in B. dorsalis, confirming their importance in reproduction. Analysis of tissue expression patterns showed that most genes, including BdABCG1, 3, 8, and 14, exhibited tissue-specificity, with significantly higher expression levels observed in the intestine, Malpighian tubule, and fat body compared to other tissues. Meanwhile, the induction of malathion and avermectin can significantly upregulate the expression of the above four genes. Furthermore, knockdown of BdABCG3 by RNAi significantly increased the mortality of B. dorsalis upon exposure to avermectin, which suggested that BdABCG3 is involved in the transport or metabolism of avermectin in B. dorsalis. Overall, our work provides valuable insights into the function of BdABCGs involved in the reproduction and detoxification system of B. dorsalis.

Identification and characterization of ABC proteins in an important rice insect pest, Cnaphalocrocis medinalis unveil their response to Cry1C toxin

Rice leaffolder (Cnaphalocrocis medinalis) is an important insect pest in paddy fields. Due to their essential role in the physiology and insecticidal resistance, ATP-binding cassette (ABC) proteins were studied in many insects. In this study, we identified the ABC proteins in C. medinalis through genomic data and analyzed their molecular characteristics. A total of 37 sequences with nucleotide-binding domain (NBD) were identified as ABC proteins and belonged to eight families (ABCA-ABCH). Four structure styles of ABC proteins were found in C. medinalis, including full structure, half structure, single structure, and ABC2 structure. In addition to these structures, TMD-NBD-TMD, NBD-TMD-NBD, and NBD-TMD-NBD-NBD were found in C. medinalis ABC proteins. Docking studies suggested that in addition to the soluble ABC proteins, other ABC proteins including ABCC4, ABCH1, ABCG3, ABCB5, ABCG1, ABCC7, ABCB3, ABCA3, and ABCC5 binding with Cry1C had higher weighted scores. The upregulation of ABCB1 and downregulation of ABCB3, ABCC1, ABCC7, ABCG1, ABCG3, and ABCG6 were associated with the C. medinalis response to Cry1C toxin. Collectively, these results help elucidate the molecular characteristics of C. medinalis ABC proteins, pave the way for further functional studies of C. medinalis ABC proteins, including their interaction with Cry1C toxin, and provide potential insecticide targets.

Unraveling cellular and molecular mechanisms of acid stress tolerance and resistance in marine species: New frontiers in the study of adaptation to ocean acidification

Since the industrial revolution, fossil fuel combustion has led to a 30 %-increase of the atmospheric CO₂ concentration, also increasing the ocean partial CO₂ pressure. The consequent lowered surface seawater pH is termed ocean acidification (OA) and severely affects marine life on a global scale. Cellular and molecular responses of marine species to lowered seawater pH have been studied but information on the mechanisms driving the tolerance of adapted species to comparatively low seawater pH is limited. Such information may be obtained from species inhabiting sites with naturally low water pH that have evolved remarkable abilities to tolerate such conditions. This review gathers information on current knowledge about species naturally facing low water pH conditions and on cellular and molecular adaptive mechanisms enabling the species to survive under, and even benefit from, adverse pH conditions. Evidences derived from case studies on naturally acidified systems and on resistance mechanisms will guide predictions on the consequences of future adverse OA scenarios for marine biodiversity.

Comparative genomic analysis of ABC transporter genes in Tenebrio molitor and four other tenebrionid beetles (Coleoptera: Tenebrionidea)

ATP-binding cassette (ABC) transporters, one of the largest transmembrane protein families, transport a diverse number of substate across membranes. Details of their diverse physiological functions have not been established. Here, we identified 87 ABC transporter genes in the genomes of Tenebrio molitor along with those from Asbolus verrucosus (104), Hycleus cichorii (65), and Hycleus phaleratus (80). Combining these genes (336 in total) with genes reported in Tribolium castaneum (73), we analyzed the phylogeny of ABC transporter genes in all five Tenebrionids. They are assigned into eight subfamilies (ABCA-H). In comparison to other species, the ABCC subfamily in this group of beetles appears expanded. The expression profiles of the T. molitor genes at different life stages and in various tissues were also investigated using transcriptomic analysis. Most of them display developmental specific expression patterns, suggesting to us their possible roles in development. Most of them are highly expressed in detoxification-related tissues including gut and Malpighian tubule, from which we infer their roles in insecticide resistance. We detected specific or abundant expressions of many ABC transporter genes in various tissues such as salivary gland, ovary, testis, and antenna. This new information helps generate new hypotheses on their biological significance within tissues.

Transcriptomic modulation in response to an intoxication with deltamethrin in a population of Triatoma infestans with low resistance to pyrethroids

Background

Triatoma infestans is the main vector of Chagas disease in the Southern Cone. The resistance to pyrethroid insecticides developed by populations of this species impairs the effectiveness of vector control campaigns in wide regions of Argentina. The study of the global transcriptomic response to pyrethroid insecticides is important to deepen the knowledge about detoxification in triatomines.

Methodology and findings

We used RNA-Seq to explore the early transcriptomic response after intoxication with deltamethrin in a population of T. infestans which presents low resistance to pyrethroids. We were able to assemble a complete transcriptome of this vector and found evidence of differentially expressed genes belonging to diverse families such as chemosensory and odorant-binding proteins, ABC transporters and heat-shock proteins. Moreover, genes related to transcription and translation, energetic metabolism and cuticle rearrangements were also modulated. Finally, we characterized the repertoire of previously uncharacterized detoxification-related gene families in T. infestans and Rhodnius prolixus.

Conclusions and significance

Our work contributes to the understanding of the detoxification response in vectors of Chagas disease. Given the absence of an annotated genome from T. infestans, the analysis presented here constitutes a resource for molecular and physiological studies in this species. The results increase the knowledge on detoxification processes in vectors of Chagas disease, and provide relevant information to explore undescribed potential insecticide resistance mechanisms in populations of these insects.

Multidrug Resistance in Cancer Cells: Focus on a Possible Strategy Plan to Address Colon Carcinoma Cells

Even though various treatment methods are available for cancer, the death curve is not reducing. The diagnosis of cancer at the fourth stage and drug resistance are the leading reasons for treatment failure and lower survival rates. In this review article, we summarize the possible pitfalls during cancer treatment in general, which mainly include multidrug resistance, and propose a hypothesis for colorectal cancer specifically. We also evaluate multidrug resistance in cancer in general and colorectal cancer in particular and hypothesize a concept based on combination therapy with 5-fluorouracil, curcumin, and lipids for the possible management of colorectal cancer. In addition, a hypothetical approach, combining a synthetic agent and a natural chemotherapeutic agent, to treating colorectal cancer is also discussed. This hypothesis could improve the management of colorectal cancer.

A near-chromosome level genome assembly of the European hoverfly, Sphaerophoria rueppellii (Diptera: Syrphidae), provides comparative insights into insecticide resistance-related gene family evolution

BACKGROUND

Sphaerophoria rueppellii, a European species of hoverfly, is a highly effective beneficial predator of hemipteran crop pests including aphids, thrips and coleopteran/lepidopteran larvae in integrated pest management (IPM) programmes. It is also a key pollinator of a wide variety of important agricultural crops. No genomic information is currently available for S. rueppellii. Without genomic information for such beneficial predator species, we are unable to perform comparative analyses of insecticide target-sites and genes encoding metabolic enzymes potentially responsible for insecticide resistance, between crop pests and their predators. These metabolic mechanisms include several gene families - cytochrome P450 monooxygenases (P450s), ATP binding cassette transporters (ABCs), glutathione-S-transferases (GSTs), UDP-glycosyltransferases (UGTs) and carboxyl/choline esterases (CCEs).

METHODS AND FINDINGS

In this study, a high-quality near-chromosome level de novo genome assembly (as well as a mitochondrial genome assembly) for S. rueppellii has been generated using a hybrid approach with PacBio long-read and Illumina short-read data, followed by super scaffolding using Hi-C data. The final assembly achieved a scaffold N50 of 87Mb, a total genome size of 537.6Mb and a level of completeness of 96% using a set of 1,658 core insect genes present as full-length genes. The assembly was annotated with 14,249 protein-coding genes. Comparative analysis revealed gene expansions of CYP6Zx P450s, epsilon-class GSTs, dietary CCEs and multiple UGT families (UGT37/302/308/430/431). Conversely, ABCs, delta-class GSTs and non-CYP6Zx P450s showed limited expansion. Differences were seen in the distributions of resistance-associated gene families across subfamilies between S. rueppellii and some hemipteran crop pests. Additionally, S. rueppellii had larger numbers of detoxification genes than other pollinator species.

CONCLUSION AND SIGNIFICANCE

This assembly is the first published genome for a predatory member of the Syrphidae family and will serve as a useful resource for further research into selectivity and potential tolerance of insecticides by beneficial predators. Furthermore, the expansion of some gene families often linked to insecticide resistance and selectivity may be an indicator of the capacity of this predator to detoxify IPM selective insecticides. These findings could be exploited by targeted insecticide screens and functional studies to increase effectiveness of IPM strategies, which aim to increase crop yields by sustainably and effectively controlling pests without impacting beneficial predator populations.

Genome-wide identification, characterization, and expression profiling of ATP-binding cassette (ABC) transporter genes potentially associated with abamectin detoxification in Cydia pomonella

The codling moth Cydia pomonella L. (Lepidoptera: Tortricidae) is one of the most notorious pests of pome fruits and walnuts worldwide, which has developed resistance to almost all classes of insecticides, including abamectin (ABM). ATP-binding cassette (ABC) transporters are thought to play a vital roles in insecticide detoxification by reducing the toxic concentrations of insecticides in an organism tissues. Despite the tremendous progress in understanding the detoxification mechanisms at the molecular level, the physiological functions of ABC transporters in insects have been poorly investigated. In this study, we found that the ABC inhibitor verapamil synergized significantly the toxicity of ABM, suggesting a potential role of ABC in detoxification. A total of 54 ABC genes were identified in the third-instar larvae of C. pomonella after treatment with sublethal doses (LD10 and LD30) of ABM. The expression profile of these genes in ABM-treated larvae at different time points (24, 48, 72 hr) using transcriptomic analysis (RNA-seq) was also investigated. The results showed that the expression of about 30 ABC genes was significantly co-upregulated after treatment. Several specific genes were up-regulated at 48 hr after treatment of larvae with LD10 ABM. Among these up-regulated genes, we found that the relative expression level of the CPOM19553 was 29.7-fold and 16.0-fold higher when larvae were exposed to ABM at the LD10 and LD30 doses compared to control, respectively. Unlike other ABC genes, only CPOM08323 exhibited significant expression levels in the head and cuticle of the third-instar larvae of C. pomonella exposed to the two sublethal doses of ABM, with no expression was observed in the detoxification tissues such as midgut and Malpighian tubule. This study suggests that these up-regulated genes may be involved in ABM resistance in C. pomonella. Our findings will provide an additional information required for further analysis of ABC transporter genes associated with xenobiotic metabolism in C. pomonella.

Expression and Function of ABC Proteins in Fish Intestine

In fish, the intestine is fundamental for digestion, nutrient absorption, and other functions like osmoregulation, acid-base balance, and excretion of some metabolic products. These functions require a large exchange surface area, which, in turn, favors the absorption of natural and anthropogenic foreign substances (xenobiotics) either dissolved in water or contained in the food. According to their chemical nature, nutrients, ions, and water may cross the intestine epithelium cells' apical and basolateral membranes by passive diffusion or through a wide array of transport proteins and also through endocytosis and exocytosis. In the same way, xenobiotics can cross this barrier by passive diffusion or taking advantage of proteins that transport physiological substrates. The entry of toxic substances is counterbalanced by an active efflux transport mediated by diverse membrane proteins, including the ATP binding cassette (ABC) proteins. Recent advances in structure, molecular properties, and functional studies have shed light on the importance of these proteins in cellular and organismal homeostasis. There is abundant literature on mammalian ABC proteins, while the studies on ABC functions in fish have mainly focused on the liver and, to a minor degree, on the kidney and other organs. Despite their critical importance in normal physiology and as a barrier to prevent xenobiotics incorporation, fish intestine's ABC transporters have received much less attention. All the ABC subfamilies are present in the fish intestine, although their functionality is still scarcely studied. For example, there are few studies of ABC-mediated transport made with polarized intestinal preparations. Thus, only a few works discriminate apical from basolateral transport activity. We briefly describe the main functions of each ABC subfamily reported for mammals and other fish organs to help understand their roles in the fish intestine. Our study considers immunohistochemical, histological, biochemical, molecular, physiological, and toxicological aspects of fish intestinal ABC proteins. We focus on the most extensively studied fish ABC proteins (subfamilies ABCB, ABCC, and ABCG), considering their apical or basolateral location and distribution along the intestine. We also discuss the implication of fish intestinal ABC proteins in the transport of physiological substrates and aquatic pollutants, such as pesticides, cyanotoxins, metals, hydrocarbons, and pharmaceutical products.

Insecticide resistance in the Cydia pomonella (L): Global status, mechanisms, and research directions

The codling moth, Cydia pomonella (Lepidoptera: Tortricidae) is a major pest of pome fruit and walnuts worldwide. Although environmentally compatible integrated control strategies, such as mating disruption, attract-kill strategy, and sterile insect technique have been conducted for management of this notorious pest, effects to control of codling moth have mainly relied on insecticides. In consequence, different levels of insecticide resistance towards organophosphates, neonicotinoids, hydrazines, benzoylureas, pyrethroids, diamides, spinosyns, avermectins, JH mimics, carbamates, oxadiazines and C. pomonella granulovirus (CpGVs) have developed in codling moth in different countries and areas. Both metabolic and target-site mechanisms conferring resistance have been revealed in the codling moth. In this review, we summarize the current global status of insecticide resistance, the biochemical and molecular mechanisms involved, and the implications for resistance management.

Delineating the Role of Aedes aegypti ABC Transporter Gene Family during Mosquito Development and Arboviral Infection via Transcriptome Analyses

Aedes aegypti acts as a vector for several arboviral diseases that impose a major socio-economic burden. Moreover, the absence of a vaccine against these diseases and drug resistance in mosquitoes necessitates the development of new control strategies for vector-borne diseases. ABC transporters that play a vital role in immunity and other cellular processes in different organisms may act as non-canonical immune molecules against arboviruses, however, their role in mosquito immunity remains unexplored. This study comprehensively analyzed various genetic features of putative ABC transporters and classified them into A-H subfamilies based on their evolutionary relationships. Existing RNA-sequencing data analysis indicated higher expression of cytosolic ABC transporter genes (E & F Subfamily) throughout the mosquito development, while members of other subfamilies exhibited tissue and time-specific expression. Furthermore, comparative gene expression analysis from the microarray dataset of mosquito infected with dengue, yellow fever and West Nile viruses revealed 31 commonly expressed ABC transporters suggesting a potentially conserved transcriptomic signature of arboviral infection. Among these, only a few transporters of ABCA, ABCC and ABCF subfamily were upregulated, while most were downregulated. This indicates the possible involvement of ABC transporters in mosquito immunity.

Comparative and functional genomics of the ABC transporter superfamily across arthropods

BACKGROUND

The ATP-binding cassette (ABC) transporter superfamily is comprised predominantly of proteins which directly utilize energy from ATP to move molecules across the plasma membrane. Although they have been the subject of frequent investigation across many taxa, arthropod ABCs have been less well studied. While the manual annotation of ABC transporters has been performed in many arthropods, there has so far been no systematic comparison of the superfamily within this order using the increasing number of sequenced genomes. Furthermore, functional work on these genes is limited.

RESULTS

Here, we developed a standardized pipeline to annotate ABCs from predicted proteomes and used it to perform comparative genomics on ABC families across arthropod lineages. Using Kruskal-Wallis tests and the Computational Analysis of gene Family Evolution (CAFE), we were able to observe significant expansions of the ABC-B full transporters (P-glycoproteins) in Lepidoptera and the ABC-H transporters in Hemiptera. RNA-sequencing of epithelia tissues in the Lepidoptera Helicoverpa armigera showed that the 7 P-glycoprotein paralogues differ substantially in their tissue distribution, suggesting a spatial division of labor. It also seems that functional redundancy is a feature of these transporters as RNAi knockdown showed that most transporters are dispensable with the exception of the highly conserved gene Snu, which is probably due to its role in cuticular formation.

CONCLUSIONS

We have performed an annotation of the ABC superfamily across > 150 arthropod species for which good quality protein annotations exist. Our findings highlight specific expansions of ABC transporter families which suggest evolutionary adaptation. Future work will be able to use this analysis as a resource to provide a better understanding of the ABC superfamily in arthropods.

ATP binding cassette importers in eukaryotic organisms

ATP-binding cassette (ABC) transporters are ubiquitous across all realms of life. Dogma suggests that bacterial ABC transporters include both importers and exporters, whilst eukaryotic members of this family are solely exporters, implying that ABC import function was lost during evolution. This view is being challenged, for example energy-coupling factor (ECF)-type ABC importers appear to fulfil important roles in both algae and plants where they form the ABCI sub-family. Herein we discuss whether bacterial Type I and Type II ABC importers also made the transition into extant eukaryotes. Various studies suggest that Type I importers exist in algae and the liverwort family of primitive non-vascular plants, but not in higher plants. The existence of eukaryotic Type II importers is also supported: a transmembrane protein homologous to vitamin B12 import system transmembrane protein (BtuC), hemin transport system transmembrane protein (HmuU) and high-affinity zinc uptake system membrane protein (ZnuB) is present in the Cyanophora paradoxa genome. This protein has homologs within the genomes of red algae. Furthermore, its candidate nucleotide-binding domain (NBD) shows closest similarity to other bacterial Type II importer NBDs such as BtuD. Functional studies suggest that Type I importers have roles in maintaining sulphate levels in the chloroplast, whilst Type II importers probably act as importers of Mn²⁺ or Zn²⁺ , as inferred by comparisons with bacterial homologs. Possible explanations for the presence of these transporters in simple plants, but not in other eukaryotic organisms, are considered. In order to utilise the existing nomenclature for eukaryotic ABC proteins, we propose that eukaryotic Type I and II importers be classified as ABCJ and ABCK transporters, respectively.