An electropenetrography waveform library for the probing and ingestion behaviors of Culex tarsalis on human hands

Culex tarsalis Coquillett (Diptera: Culicidae) mosquitoes are capable of vectoring numerous pathogens affecting public and animal health. Unfortunately, the probing behaviors of mosquitoes are poorly understood because they occur in opaque tissues. Electropenetrography (EPG) has the potential to elucidate these behaviors by recording the electrical signals generated during probing. We used an AC-DC EPG with variable input resistors (Ri levels) to construct a waveform library for Cx. tarsalis feeding on human hands. Biological events associated with mosquito probing were used to characterize waveforms at four Ri levels and with two electrical current types. The optimal settings for EPG recordings of Cx. tarsalis probing on human hands was an Ri level of 107 Ohms using an applied signal of 150 millivolts alternating current. Waveforms for Cx. tarsalis included those previously observed and associated with probing behaviors in Aedes aegypti L. (Diptera: Culicidae): waveform families J (surface salivation), K (stylet penetration through the skin), L (types 1 and 2, search for a blood vessel/ingestion site), M (types 1 and 2, ingestion), N (type 1, an unknown behavior which may be a resting and digestion phase), and W (withdrawal). However, we also observed variations in the waveforms not described in Ae. aegypti, which we named types L3, M3, M4, and N2. This investigation enhances our understanding of mosquito probing behaviors. It also provides a new tool for the automated calculation of peak frequency. This work will facilitate future pathogen acquisition and transmission studies and help identify new pest and disease management targets.

Evaluation of potential reference genes in the biting midge Culicoides sonorensis for real-time quantitative PCR analyses

Studies examining differentially expressed genes and gene silencing by RNA interference (RNAi) require a set of stably expressed reference genes for accurate normalization. The biting midge Culicoides sonorensis is an important vector of livestock pathogens and is often used as a model species for biting midge research. Here, we examine the stable expression of six candidate reference genes in C. sonorensis: actin, β-tubulin, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), ribosomal protein subunit (RPS) 18, vacuolar ATPase subunit A (VhaA), and elongation factor 1-beta (EF1b). Gene expression was assessed under seven conditions, including cells treated with double-stranded RNA (dsRNA), 3rd and 4th instar larvae treated with dsRNA, six developmental stages, four adult female body parts or tissue groups, and females injected with bluetongue virus or vesicular stomatitis virus. Stable gene expression was assessed using RefFinder, NormFinder, geNorm, and BestKeeper. The ranked results for each analysis tool under each condition and a comprehensive ranking for each condition are presented. The data show that optimal reference genes vary between conditions and that just two reference genes were necessary for each condition. These findings provide reference genes for use under these conditions in future studies using real-time quantitative PCR to evaluate gene expression in C. sonorensis.

Diversity of the Bacterial and Viral Communities in the Tropical Horse Tick, Dermacentor nitens, in Colombia

Ticks are obligatory hematophagous ectoparasites that transmit pathogens among various vertebrates, including humans. The microbial and viral communities of ticks, including pathogenic microorganisms, are known to be highly diverse. However, the factors driving this diversity are not well understood. The tropical horse tick, Dermacentor nitens, is distributed throughout the Americas and it is recognized as a natural vector of Babesia caballi and Theileria equi, the causal agents of equine piroplasmosis. In this study, we characterized the bacterial and viral communities associated with partially fed Dermacentor nitens females collected using a passive survey on horses from field sites representing three distinct geographical areas in the country of Colombia (Bolivar, Antioquia, and Cordoba). RNA-seq and sequencing of the V3 and V4 hypervariable regions of the 16S rRNA gene were performed using the Illumina-Miseq platform (Illumina, San Diego, CA, USA). A total of 356 operational taxonomic units (OTUs) were identified, in which the presumed endosymbiont, Francisellaceae/Francisella spp., was predominantly found. Nine contigs corresponding to six different viruses were identified in three viral families: Chuviridae, Rhabdoviridae, and Flaviviridae. Differences in the relative abundance of the microbial composition among the geographical regions were found to be independent of the presence of Francisella-like endosymbiont (FLE). The most prevalent bacteria found in each region were Corynebacterium in Bolivar, Staphylococcus in Antioquia, and Pseudomonas in Cordoba. Rickettsia-like endosymbionts, mainly recognized as the etiological agent of rickettsioses in Colombia, were detected in the Cordoba samples. Metatranscriptomics revealed 13 contigs containing FLE genes, suggesting a trend of regional differences. These findings suggest regional distinctions among the ticks and their bacterial compositions.

Diversity of the bacterial and viral communities in the tropical horse tick, Dermacentor nitens in Colombia

Ticks are obligatory hematophagous ectoparasites that transmit pathogens among various vertebrates, including humans. The composition of the microbial and viral communities in addition to the pathogenic microorganisms is highly diverse in ticks, but the factors driving the diversity are not well understood. The tropical horse tick, Dermacentor nitens , is distributed throughout the Americas and it is recognized as a natural vector of Babesia caballi and Theileria equi , the causal agents of equine piroplasmosis. We characterized the bacterial and viral communities associated with partially-fed D. nitens females collected by a passive survey on horses from field sites representing three distinct geographical areas in Colombia (Bolivar, Antioquia, and Cordoba). RNA-seq and sequencing of the V3 and V4 hypervariable regions of the 16S rRNA gene were performed using the Illumina-Miseq platform. A total of 356 operational taxonomic units (OTUs) were identified, in which the presumed endosymbiotic Francisellaceae/ Francisella spp. was predominantly found. Nine contigs corresponding to six different viruses were identified in three viral families: Chuviridae, Rhabdoviridae, and Flaviviridae. Differences in the relative abundance of the microbial composition among the geographical regions were found to be independent of the presence of Francisella -Like Endosymbiont (FLE). The most prevalent bacteria found on each region were Corynebacterium in Bolivar, Staphylococcus in Antioquia, and Pseudomonas in Cordoba. Rickettsia -like endosymbionts, mainly recognized as the etiological agent of rickettsioses in Colombia were detected in the Cordoba samples. Metatranscriptomics revealed 13 contigs containing FLE genes, suggesting a trend of regional differences. These findings suggest regional distinctions among the ticks and their bacterial compositions.

Tobacco product menthol and flavour bans: their utility for LMIC and lessons from the EU ban

Background

Flavoured tobacco products increase smoking uptake and create dependence. By June 2020 all cigarettes with a characterising flavour, including menthol were banned across the EU, UK and Moldova but many low and middle income countries (LMIC) are yet to develop and implement bans despite high smoking prevalence. This paper has two objectives: to establish whether (1) flavoured tobacco products are present and marketed in LMIC and (2) the experience of bans in Europe can guide development of legislation elsewhere.

Methods

Research involved analysis of menthol/flavour market data, review of academic and commercial literature and online media.

Results

The median menthol/capsule market share of the cigarette market grew significantly in middle income countries (p < 0.05) between 2005 and 2019, both in lower and upper middle-income countries [lower: 2.5% (IQR: 0.5-4.0) to 6.5% (IQR: 3.6-15.9); and upper: 4.0% (IQR: 0.8-9.8) to 12.3% (IQR: 3.5-24.3)]. No market data were available on low-income countries, but the academic literature suggested high prevalence of menthol use in Zambia. Tobacco industry strategies underpinning growth of menthol/flavoured tobacco use in LMICs included in-store marketing and display, colourful packs and non-conventional flavour names. Tobacco industry attempts to circumvent the EU ban included introducing new flavoured tobacco products and accessories not included in the ban and exploiting the ban on characterising flavour (as opposed to an ingredient ban) by introducing cigarettes with lower levels of menthol.

Conclusions

Banning flavoured and menthol cigarettes in LMIC would impact a growing proportion of smokers in these countries. From the European experience, menthol and flavour bans that include all tobacco products and accessories and ban flavour as an ingredient rather than a characterising flavour is recommended. Currently, lack of marketing bans and standardised packaging in LMICs exacerbate the impact of flavours.

Key messages

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

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

Identification of Rab family genes and functional analyses of LmRab5 and LmRab11A in the development and RNA interference of Locusta migratoria

Rab proteins constitute the largest family of small GTPases, which play pivotal roles in intracellular membrane trafficking in all eukaryotes. A number of Rab genes have been identified in eukaryotes; however, very little information about these genes has been reported in insects. In the current study, for the first time we identified and characterized 27 Rab family genes from Locusta migratoria. Phylogenetic analysis and comparison of domain architecture indicated that Rab family genes are highly conserved among insect species. Tissue-dependent expression profiles indicated that expression of Rab genes was highest in the ovary, except for LmRab3, which was most highly expressed in hemolymph. The biological function of each Rab gene was investigated using RNA interference (RNAi). Double-stranded RNA targeting each Rab gene was injected into the hemocoel of nymphs and revealed that suppression of two Rab genes (LmRab5 and LmRab11A) caused 100% mortality. In addition, nymphs injected with dsLmRab5 exhibited severe phenotypic defects in the gastric caeca and midgut, while dsLmRab11A arrested the molting process. We then applied the RNAi of RNAi technique to test if silencing either of these two genes would affect the suppression of the lethal giant larvae (LmLgl) reporter gene and found that suppression of LmRab5 diminished the RNAi efficiency of LmLgl, whereas suppression of LmRab11A enhanced RNAi efficiency of LmLgl. These results indicate that Rab genes contribute differently to RNAi efficiency in different tissues. Our study provides a foundation for further functional investigations of Rab genes and their contributions to RNAi efficiency in L. migratoria.

Vacuolar (H+ )-ATPase subunit c is essential for the survival and systemic RNA interference response in Locusta migratoria

BACKGROUND

Vacuolar (H⁺ )-ATPase (V-ATPase) is a multi-subunit enzyme that hydrolyzes adenosine triphosphate (ATP) to transport protons across a cellular membrane, and it plays an important role in numerous biological processes, including in growth, development and immune responses. The c subunit of V-ATPase is a highly conserved subunit of the rotatory proteolipid ring that is required for binding and transporting protons. To date, there are only a few published reports on V-ATPase-c functions in insects.

RESULTS

We identified and characterized the V-ATPase-c gene in Locusta migratoria, one of the most destructive agricultural insect pests in the world. LmV-ATPase-c was predominately expressed in Malpighian tubules of nymphs, followed by the hindgut and ovary, while the other tissues showed relatively low expression levels. Silencing of LmV-ATPase-c caused severe molting defects in nymphs and a high mortality rate of > 90%. Histological staining and microscopic examination of sections from the abdominal cuticle revealed the absence of newly formed cuticle in nymphs that were injected with dsLmV-ATPase-c. In addition, silencing of LmV-ATPase-c transcript levels significantly impaired RNA interference (RNAi) efficiency of a reporter gene. By quantifying double-stranded RNA (dsRNA) amounts by quantitative polymerase chain reaction (PCR), we found that RNAi against LmV-ATPase-c provoked a dramatic accumulation of dsRNA in the endosomes of epidermal and midgut cells of Locusta migratoria.

CONCLUSION

Our results indicate that LmV-ATPase-c is indispensable for the formation of new cuticle during the molting process and has pivotal functions in dsRNA escape from endosomes. LmV-ATPase-c might be a valuable target for developing new strategies for insect pest management. © 2022 Society of Chemical Industry.

A dsRNA-degrading nuclease (dsRNase2) limits RNAi efficiency in the Asian corn borer (Ostrinia furnacalis)

The efficiency of RNA interference (RNAi) varies substantially among different insect species. Rapid degradation of double-stranded RNA (dsRNA) by dsRNA-degrading nucleases (dsRNases) has been implicated to cause low RNAi efficiency in several insect species. In this study, we identified four dsRNase genes (OfdsRNase1, OfdsRNase2, OfdsRNase3 and OfdsRNase4) from the Asian corn borer (Ostrinia furnacalis) transcriptome database. Bioinformatic analyses showed that each deduced protein sequence contained endonuclease NS domains and signal peptides. Gene expression analysis revealed that OfdsRNase2 was exclusively expressed in the midgut of larvae. RNAi efficiency was investigated in 2-d-old fifth-instar larvae (high expression of dsRNase2) and 2-d-old pupae (low expression of dsRNase2) by feeding or injecting dsRNA targeting a marker gene that encodes the lethal giant larvae protein (OfLgl). Our results showed that OfLgl only partially silenced the expression of OfLgl in pupae, but not in larvae, suggesting that OfdsRNase2 could contribute to lower RNAi efficiency in larval stages. This hypothesis was supported by our RNAi-of-RNAi experiment using a tissue culture technique where the silencing efficiency against the reporter gene, OfHex1, was significantly improved after knockdown of OfdsRNase2. When double luciferase assays were performed to evaluate the role of the four dsRNases in vitro, only OfdsRNase2 expressed in S2 cells significantly affected RNAi efficiency by degrading dsRNA. Taken together, our results suggested that the degradation of dsRNA by OfdsRNase2 in the midgut contributed to low RNAi efficiency in O. furnacalis larvae.

Strategies for enhancing the efficiency of RNA interference in insects

Low RNA interference (RNAi) efficiency in many insect pests has significantly prevented its widespread application for insect pest management. This article provides a comprehensive review of recent research in developing various strategies for enhancing RNAi efficiency. Our review focuses on the strategies in target gene selection and double-stranded RNA (dsRNA) delivery technologies. For target gene selection, genome-wide or large-scale screening strategies have been used to identify most susceptible target genes for RNAi. Other strategies include the design of dsRNA constructs and manipulate the structure of dsRNA to maximize the RNA efficiency for a target gene. For dsRNA delivery strategies, much recent research has focused on the applications of complexed or encapsulated dsRNA using various reagents, polymers, or peptides to enhance dsRNA stability and cellular uptake. Other dsRNA delivery strategies include genetic engineering of microbes (e.g. fungi, bacteria, and viruses) and plants to produce insect-specific dsRNA. The ingestion of the dsRNA-producing organisms or tissues will have lethal or detrimental effects on the target insect pests. This article also identifies obstacles to further developing RNAi for insect pest management and suggests future avenues of research that will maximize the potential for using RNAi for insect pest management. © 2021 Society of Chemical Industry.

Molecular characterization and RNA interference responses of the lethal giant larvae gene in Diabrotica virgifera virgifera adults

High specificity for silencing target genes and single-copy target genes that yield clear phenotypes are two important factors for the success of RNA interference (RNAi). The lethal giant larvae (Lgl) gene appears to be an ideal gene for RNAi because RNAi can effectively suppress its expression and results in molting defects and mortality in Tribolium castaneum. To investigate the suitability of this gene for RNAi in other insects, we identified and characterized DvLgl from the western corn rootworm, Diabrotica virgifera virgifera, a species exhibiting high RNAi efficiency. DvLgl was expressed in all developmental stages and tissues investigated. The deduced DvLgl protein showed high amino-acid sequence identities and similar domain architecture to Lgls from other insect species. Despite many similarities among insect Lgls, RNAi-mediated suppression of DvLgl failed to produce a phenotype in D. v. virgifera adults. The difference in developing phenotypes could be attributed greatly to the level of gene suppression and the insect developmental stages for RNAi. These results highlight the variability in RNAi response among insects and showcase the importance of screening multiple target genes when conducting RNAi studies. Our findings are expected to help the design of future RNAi studies and future investigations of Lgl in insects.

Comparison of strategies for enhancing RNA interference efficiency in Ostrinia nubilalis

BACKGROUND

Targeting insect-specific genes through post-transcriptional gene silencing with RNA interference (RNAi) is a new strategy for insect pest management. However, lepidopterans are recalcitrant to RNAi, which prevents application of novel RNAi technology to many notorious pests, including Ostrinia nubilalis (ECB). Strategies for enhancing RNAi efficiency, including large doses of double-stranded RNA (dsRNA), nuclease inhibitors, transfection reagents, and nanoparticles, have proved useful in other insects exhibiting substantial dsRNA degradation, a major mechanism limiting RNAi efficacy. To determine if similar strategies can enhance RNAi efficiency in ECB, various reagents were tested for their ability to enhance dsRNA stability in ECB tissues, then compared for their effectiveness in whole ECB.

RESULTS

Ex vivo incubation experiments revealed that Meta dsRNA lipoplexes, EDTA, chitosan-based dsRNA nanoparticles, and Zn²⁺ enhanced dsRNA stability in ECB hemolymph and gut content extracts, compared with uncoated dsRNA. Despite these positive results, the reagents used in this study were ineffective at enhancing RNAi efficiency in ECB in vivo. To reduce assay time and required dsRNA, midguts were dissected and incubated in tissue culture medium containing dsRNA with and without reagents. These experiments showed that RNAi efficiency varied between target genes, and nuclease inhibitors improved RNAi efficiency for only a portion of the refractory target genes investigated ex vivo.

CONCLUSION

These results indicate that enhancing dsRNA stability is insufficient to improve RNAi efficiency in ECB and suggests the existence of additional, complex mechanisms contributing to low RNAi efficiency in ECB.

Characterization, expression patterns, and transcriptional responses of three core RNA interference pathway genes from Ostrinia nubilalis

RNA interference (RNAi) is commonly used in the laboratory to analyze gene function, and RNAi-based pest management strategies are now being employed. Unfortunately, RNAi is hindered by inefficient and highly-variable results when different insects are targeted, especially lepidopterans, such as the European corn borer (ECB), Ostrinia nubilalis (Lepidoptera: Crambidae). Previous efforts to achieve RNAi-mediated gene suppression in ECB revealed low RNAi efficiency with both double-stranded RNA (dsRNA) injection and ingestion. One mechanism that can affect RNAi efficiency in insects is the expression and function of core RNAi pathway genes, such as those encoding Argonaut 2 (Ago2), Dicer 2 (Dcr2), and a dsRNA binding protein (R2D2). To determine if deficiencies in these core RNAi pathway genes contribute to low RNAi efficiency in ECB, full-length complementary DNAs encoding OnAgo2, OnDcr2, and OnR2D2 were cloned, sequenced, and characterized. A comparison of domain architecture suggested that all three predicted proteins contained the necessary domains to function. However, a comparison of evolutionary distances revealed potentially important variations in the first RNase III domain of OnDcr2, the double-stranded RNA binding domains of OnR2D2, and both the PAZ and PIWI domains of OnAgo2, which may indicate functional differences in enzymatic activity between species. Expression analysis indicated that transcripts for all three genes were expressed in all developmental stages and tissues investigated. Interestingly, the introduction of non-target dsRNA into ECB second-instar larvae via microinjection did not affect OnAgo2, OnDcr2, or OnR2D2 expression. In contrast, ingestion of the same dsRNAs resulted in upregulation of OnDcr2 but downregulation of OnR2D2. The unexpected transcriptional responses of the core machinery and the divergence in amino-acid sequence between specific domains in each core RNAi protein may possibly contribute to low RNAi efficiency in ECB. Understanding the contributions of different RNAi pathway components is critical to adapting this technology for use in controlling lepidopteran pests that exhibit low RNAi efficiency.

"What counts can't always be measured": a qualitative exploration of general practitioners' conceptualisation of quality for community pharmacy services

Background

The expansion of community pharmacy services is one solution to relieve pressure on general practice in the United Kingdom (UK). There is a paucity of research of general practitioners’ (GPs’) perspectives of quality of care in the community pharmacy sector.

The purpose of this study was to explore GPs’:

Conceptualisation of quality for community pharmacy services, including the management of acute (low acuity) conditions and defining indispensable aspects of the patient experience (‘always events’)

Opinions regarding whether and how to measure quality in the community pharmacy sector

Method

Semi-structured interviews were conducted with GPs in the UK. GPs were recruited using the snowballing technique and professional networks. Interviews were audio-recorded, transcribed and analysed using an interpretive approach.

Results

Interviews were completed with 20 GPs from Scotland (n = 8) and England (n = 12). Multidimensional and inter-related concepts of quality were identified; most dimensions related to patient benefit, as well as impact on GP workload or other health service provision. Interviewees cautioned that “what counts can’t always be measured”. GPs’ expectations of quality often mirrored those of their own sector, but were ambivalent about the adoption of a quality outcome framework-type approach. Pharmacist involvement was expected to ensure quality in the management of ‘acute consultations’, however, GPs lacked awareness of community pharmacy personnel type, roles and training. Interviewees’ perceptions of quality varied by pharmacy type; independent pharmacies were sometimes associated with higher quality service delivery than larger chain organisations.

Conclusions

Quality frameworks for community pharmacy services could be partly informed by GP experience and expectations, but need to be contextual to reflect differences between both settings. The importance of person-centred care, consistency and continuity was emphasised together with the need for competent personnel and privacy of interactions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12875-020-01319-2.

Multiple Argonaute family genes contribute to the siRNA-mediated RNAi pathway in Locusta migratoria

Argonautes (Ago) are important core proteins in RNA interference (RNAi) pathways of eukaryotic cells. Generally, it is thought that Ago1, Ago2 and Ago3 are involved in the miRNA (microRNA), siRNA (small interfering RNA) and piRNA (Piwi-interacting RNA)-mediated RNAi pathways, respectively. As a main component of the RNA-induced silencing complex (RISC), Ago2 plays an indispensable role in using siRNA to recognize and cut target messenger RNAs resulting in suppression of transcript levels, but the contributions of Ago1 and Ago3 to the siRNA-mediated RNAi pathway remain to be explored in many insect species. In this study, we investigated the contributions of four Ago genes (named LmAgo1, LmAgo2a and LmAgo2b and LmAgo3) to RNAi efficiency in Locusta migratoria by using both in vivo and in vitro experiments. Our results showed that suppression of each of the Ago genes significantly impaired RNAi efficiency when targeting Lmβ-tubulin transcripts, resulting in recovery of 48, 43.3, 61.4 or 26% of Lmβ-tubulin transcripts following RNAi-mediated suppression of LmAgo1, LmAgo2a, LmAgo2b, and LmAgo3, respectively. Furthermore, overexpression of LmAgo1, LmAgo2a, LmAgo2b, or LmAgo3 in a PAc5.1-V5/HisB vector and co-transfection with psicheck2 fluorescence vector in S2 cells reduced luciferase fluorescence by 38.3, 58.9, 53.3 or 55.6%, respectively. Taken together, our results showed that LmAgo1, LmAgo2a, LmAgo2b, and LmAgo3 each make significant contributions to RNAi efficiency in L. migratoria and suggest that the involvement of all four enzymes could be one of the major factors supporting robust RNAi responses observed in this species.

Stability of double-stranded RNA in gut contents and hemolymph of Ostrinia nubilalis larvae

RNA interference (RNAi) is a revolutionary technique for silencing gene expression, but the success of this technique is dependent upon the stability of double-stranded RNA (dsRNA) molecules. In many insects, especially lepidopteran species, RNAi efficiency is limited by high instability of dsRNA in the gut and/or hemolymph, preventing the development of RNAi-based strategies for many serious pests. Previous attempts to perform RNAi on Ostrinia nubilalis (ECB, Lepidoptera: Crambidae) indicate low RNAi efficiency with both dsRNA injection and feeding. To investigate the contribution of dsRNA instability to low RNAi efficiency in ECB, a serious of ex vivo incubation experiments were performed where dsRNA integrity was assessed following incubation in larval gut continents and hemolymph using gel electrophoresis or RT-qPCR. DsRNA was less stable in the gut contents from ECB than in gut contents from Diabrotica virgifera virgifera, a coleopteran exhibiting high RNAi efficiency. Furthermore, characterization of dsRNA stability in ECB gut contents and hemolymph revealed that dsRNA was rapidly degraded under physiologically relevant conditions as a result of enzymatic activity that was neither size- nor sequence-dependent. These findings suggest that instability of dsRNA in ECB tissues is a contributing factor to the poor efficiency of RNAi in this pest. This work advances our understanding of mechanisms impacting RNAi efficiency in ECB and related lepidopteran insects for which novel pest management strategies are needed, and may facilitate the development of strategies for enhancing dsRNA stability in ECB tissues.

Molecular Characterizations of Double-Stranded RNA Degrading Nuclease Genes from Ostrinia nubilalis

Simple Summary

RNA interference is a gene suppression tool that uses double-stranded RNA to prevent specific genes from producing proteins. By targeting essential genes RNA interference can be developed for control of insect pests. Unfortunately, RNA interference is not equally effective for all insects. Previous investigation suggested that RNA is rapidly digested by unidentified components of body fluids in the European corn borer caterpillar. We characterized genes encoding proteins from European corn borer that are associated with RNA digestion in other insects. Our results suggest that two proteins (RNA interference efficiency-related nuclease and double-stranded RNA-degrading endonuclease 2) may be responsible for digesting RNAs in the European corn borer gut, whereas two other proteins (double-stranded RNA-degrading endonuclease 1 and double-stranded RNA-degrading endonuclease 4) may be responsible for digesting RNA in European corn borer body fluid. These findings suggest digestion of RNA in the European corn borer is likely due to the activity of these proteins. These findings provide information about the mechanism(s) influencing RNA stability in insects. The knowledge generated by this study will facilitate the development of strategies for enhancing RNA interference in insects.

Abstract

Variable RNA interference (RNAi) efficiencies limit RNAi-based pest management strategies for many pests. Previous efforts to understand mechanisms contributing to low RNAi efficiency indicate that double-stranded RNA (dsRNA) is degraded in the European corn borer (ECB), Ostrinia nubilalis, due to nuclease activity. To investigate the contribution of dsRNA-degrading endonucleases (dsRNases) and lepidopteran-specific RNAi efficiency-related nucleases (REases) to dsRNA instability and low RNAi efficiency in ECB, five complementary DNAs putatively encoding four dsRNases (OndsRNase1, 2, 3, and 4) and one REase (OnREase) were sequenced. Characterization of these transcripts revealed that substrate specificity might vary among the four dsRNases due to different amino acid combinations in the substrate-binding sites. Gene expression analysis indicated that OndsRNase2 and OnREase were highly expressed in the larval gut, and OndsRNase1 showed the highest expression in hemolymph, especially in older developmental stages. Transcript level analysis after dsRNA exposure revealed that expression of OnREase rapidly increased upon dsRNA ingestion or injection, whereas OndsRNase4 expression only increased after long-term ingestion of dsRNA. While the biological function of these nucleases remains to be verified, our results suggest that OnREase and OndsRNase2, and OndsRNase1 and OndsRNase4 may be responsible for degradation of dsRNAs in the ECB gut and hemolymph, respectively, thereby contributing to low RNAi efficiency.

Changes in industry interference in policy in the United Kingdom 2017-2020

Background

The Tobacco Industry Interference (TII) Index evaluates the implementation of FCTC Article 5.3. The first edition of the Global TII Index was published in 2019, included 33 countries, and covered the years 2017-2018. A second edition, covering 2018-2019, is scheduled to be published in October 2020. This paper reports on findings of the Index for the UK, the changes observed between 2017 and 2020, and the resulting policy recommendations.

Methods

The UK Index was based on a questionnaire covering different forms of tobacco industry interference. Lower scores indicate better compliance with Article 5.3. In order to complete the questionnaire, an expert consultation was conducted with UK's leading tobacco control specialists. This was supplemented by a scoping review of academic literature, media websites, government websites, and the Tobacco Tactics resource.

Results

In the 2019 Index the UK has achieved the lowest score among 33 countries surveyed. Strengths of the UK system included the exclusion of TI from government bodies that set public health policy and from FCTC COP delegations; the obligation of the government to publish information on all meetings with TI; and guidelines stipulating that its diplomats must not engage on behalf of TI. Nevertheless, weaknesses were also identified; including only partial implementation of the above obligations, the absence of an effective lobbying register, and the ongoing involvement of parliamentary consultative bodies, individual politicians and political parties with TI and affiliated organisations.

Discussion

The change of government in the UK in 2019, the shifting policy framework resulting from Brexit, and the increasing use by the tobacco industry of third parties to access policymakers, bring new challenges to the maintenance of robust Article 5.3 compliance. The presentation will analyse how this has affected the change in the UK's performance between the 2019 and the 2020 Tobacco Industry Interference Index.

Key messages

The need to strengthen transparency regulations for policymakers. A need for continued monitoring against an agreed framework in the light of very fluid political developments.

Progress and prospects of arthropod chitin pathways and structures as targets for pest management

Chitin is a structural component of the arthropod cuticular exoskeleton and the peritrophic matrix of the gut, which play crucial roles in growth and development. In the past few decades, our understanding of the composition, biosynthesis, assembly, degradation, and regulation of chitinous structures has increased. Many chemicals have been developed that target chitin biosynthesis (benzoyphenyl ureas, etoxazole), chitin degradation (allosamidin, psammaplin), and chitin regulation (benzoyl hydrazines), thus resulting in molting deformities and lethality. In addition, proteins that disrupt chitin structures, such as lectins, proteases, and chitinases have been utilized to halt feeding and induce mortality. Chitin-degrading enzymes, such as chitinases are also useful for improving the efficacy of bio-insecticides. Transgenic plants, baculoviruses, fungi, and bacteria have been engineered to express chitinases from a variety of organisms for control of arthropod pests. In addition, RNA interference targeting genes involved in chitin pathways and structures are now being investigated for the development of environmentally friendly pest management strategies. This review describes the chemicals and proteins used to target chitin structures and enzymes for arthropod pest management, as well as pest management strategies based upon these compounds, such as plant-incorporated-protectants and recombinant entomopathogens. Recent advances in RNA interference-based pest management, and how this technology can be used to target chitin pathways and structures are also discussed.

Metabolism of selected model substrates and insecticides by recombinant CYP6FD encoded by its gene predominately expressed in the brain of Locusta migratoria

The migratory locust, Locusta migartoria, is a major agricultural insect pest and its resistance to insecticides is becoming more prevalent. Cytochrome P450 monooxygenases (CYPs) are important enzymes for biotransformations of various endogenous and xenobiotic substances. These enzymes play a major role in developing insecticide resistance in many insect species. In this study, we heterologously co-expressed a CYP enzyme (CYP6FD1) and cytochrome P450 reductase (CPR) from L. migartoria in Sf9 insect cells. The recombinant enzymes were assayed for metabolic activity towards six selected model substrates (luciferin-H, luciferin-Me, luciferin-Be, luciferin-PFBE, luciferin-CEE and 7-ethoxycoumarin), and four selected insecticides (deltamethrin, chlorpyrifos, carbaryl and methoprene). Recombinant CYP6FD1 showed activity towards 7-ethoxycoumarin and luciferin-Me, but no detectable activity towards the other luciferin derivatives. Furthermore, the enzyme efficiently oxidized deltamethrin to hydroxydeltamethrin through an aromatic hydroxylation in a time-dependent manner. However, the enzyme did not show any detectable activity towards the other three insecticides. Our results provide direct evidence that CYP6FD1 is capable of metabolizing deltamethrin. This work is a step towards a more complete characterization of the catalytic capabilities of CYP6FD1 and other xenobiotic metabolizing CYP enzymes in L. migratoria.

Contributions of dsRNases to differential RNAi efficiencies between the injection and oral delivery of dsRNA in Locusta migratoria

BACKGROUND

The efficiency of RNA interference (RNAi) varies considerably among different insect species, and there is growing evidence to suggest that degradation of double-stranded (dsRNA) prior to uptake is an important factor that limits the efficiency of RNAi in insects. In Locusta migratoria, RNAi is highly efficient when dsRNA is delivered by injection, but not by feeding. However, detailed mechanisms causing such differential RNAi efficiency are still elusive.

RESULTS

We identified and characterized the full-length complementary DNAs (cDNAs) of two new dsRNA nuclease (dsRNase) genes from L. migratoria, which were named LmdsRNase1 and LmdsRNase4. Transcript analyses revealed that LmdsRNase1 and LmdsRNase4 were highly expressed in hemolymph with relatively lower expression in other tested tissues. Our study using heterologously expressed LmdsRNase1 and LmdsRNase4 fusion proteins showed that LmdsRNase1 can degrade dsRNA rapidly at an optimal pH of 5, whereas LmdsRNase4 had no activity at any of the pH values examined. In comparing the substrate specificity of the four LmdsRNases, we found that only LmdsRNase1 and LmdsRNase2 digested dsRNA; however, our experiments suggested that the physiological pH of hemolymph (7.0) suppresses LmdsRNase1 activity permitting significant dsRNA stability in this tissue. Conversely, the physiological pH of midgut juice (6.8) is ideal for LmdsRNase2 activity, resulting in degradation of dsRNA in midgut.

CONCLUSION

The physiological pH of different insect tissues or compartments can significantly alter the stability of dsRNA by influencing LmdsRNase activity in L. migratoria. Thus, new strategies to overcome such obstacles are expected to help implement RNAi-based technologies for insect pest management. © 2018 Society of Chemical Industry.

Molecular mechanisms influencing efficiency of RNA interference in insects

RNA interference (RNAi) is an endogenous, sequence-specific gene-silencing mechanism elicited by small RNA molecules. RNAi is a powerful reverse genetic tool, and is currently being utilized for managing insects and viruses. Widespread implementation of RNAi-based pest management strategies is currently hindered by inefficient and highly variable results when different insect species, strains, developmental stages, tissues, and genes are targeted. Mechanistic studies have shown that double-stranded ribonucleases (dsRNases), endosomal entrapment, deficient function of the core machinery, and inadequate immune stimulation contribute to limited RNAi efficiency. However, a comprehensive understanding of the molecular mechanisms limiting RNAi efficiency remains elusive. Recent advances in dsRNA stability in physiological tissues, dsRNA internalization into cells, the composition and function of the core RNAi machinery, as well as small-interfering RNA/double-stranded RNA amplification and spreading mechanisms are reviewed to establish a global understanding of the obstacles impeding wider understanding of RNAi mechanisms in insects. © 2018 Society of Chemical Industry.

Comparisons of microsomal cytochrome P450 content and enzymatic activity towards selected model substrates and insecticides in different tissues from the migratory locust (Locusta migratoria)

Cytochrome P450 monooxygenases (P450s) are important enzymes for biotransformations of various endogenous and xenobiotic substances in various organisms. In this study, we examined microsomal P450 protein content and enzymatic activity in four major detoxification tissues dissected from fifth-instar nymphs of the migratory locust (Locusta migratoria). The highest microsomal P450 protein content was found in the gastric caeca (a part of the midgut), followed by the midgut, Malpighian tubules and fat bodies. Microsomal P450s showed the highest aromatic hydroxylation, O-dealkylation and O-dearylation activities towards six of the seven model substrates examined in the fat bodies. Although the gastric caeca showed the highest P450 protein content, the enzymatic activities towards six of the seven model substrates were the lowest in this tissue. Further, the midgut, gastric caeca and fat bodies showed significant metabolic activities towards two pyrethroid insecticides (deltamethrin and fluvalinate), but no significant activities towards the other four insecticides (malathion, chlorpyrifos, carbaryl and methoprene). These results support our conclusions: 1) total P450 protein content alone cannot be reliably used to predict its enzymatic activity, and 2) insect P450 enzymatic activity is both tissue and substrate dependent.

Transcriptome-wide survey, gene expression profiling and exogenous chemical-induced transcriptional responses of cytochrome P450 superfamily genes in migratory locust (Locusta migratoria)

Cytochrome P450 monooxygenases (CYPs) belong to a large superfamily of heme-containing enzymes catalyzing at least 60 different types of chemically distinct reactions. Insect CYPs play key roles in biotransformation of insecticides and plant chemicals, and are implicated in insecticide resistance and insect adaptation to their host plants. Insect CYPs are well studied in model insects, but little is known about the CYP superfamily in paurometabolous insects. We employed Illumina sequencing technology to identify 71 partial and 78 full-length open reading frames (ORFs) of LmCYP genes from the migratory locust (Locusta migratoria), one of the most destructive paurometabolous insect pests in the world. Seventy-eight LmCYPs with complete ORFs were formally named and classified into 19 families and 43 subfamilies. The majority of LmCYPs were mainly expressed in nymphal and adult stages, but LmCYP expression varied widely among thirteen different tissues examined. Regulatory elements were predicted in the promoter regions of LmCYP genes, and subsequent exposure of locusts to 12 different exogenous chemicals showed that 2-tridecanone and xanthotoxin were the most effective at increasing LmCYP expression. Our results represent the first transcriptome-wide analysis of the LmCYP superfamily from migratory locust, and provide a foundation for understanding the physiological functions, functional diversity, evolution, and regulatory mechanisms controlling the expression of the CYP gene superfamily in the locust.

Heterologous Co-expression of CYP6B7 and NADPH-Dependent Cytochrome P450 Reductase From Helicoverpa armigera (Lepidoptera: Noctuidae) in Pichia pastoris

As important metabolic enzymes, the function of cytochrome P450 monooxygenases (CYPs) has been demonstrated repeatedly through various means, including heterologous expression systems. Unfortunately, most model systems typically lack expression of a conspecific NADPH-dependent cytochrome P450 reductase (CPR), which is the electron transfer partner of CYPs. As a result, the activities of heterologously expressed insect CYPs may not accurately reflect detoxification activities in vivo. Previously, CYP6B7 from Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) (HaCYP6B7) has been expressed in the Pichia pastoris GS115 strain and shown to detoxify bifenthrin, fenvalerate and chlorpyrifos. However, it remains to be determined if co-expression of HaCYP6B7 with HaCPR will enhance the detoxification ability of the expression system. In the present study, HaCYP6B7 and HaCPR genes were co-expressed in P. pastoris using a reconstituted expression vector, pPICZA-HaCYP6B7-HaCPR. Protein expression was confirmed by Western blot, and the detoxification activities of microsomal fractions to p-nitroanisole O-demethylation (PNOD), 7-ethoxycoumarin O-deethylation (ECOD), fenvalerate and chlorpyrifos were measured. Co-expression of HaCYP6B7 with HaCPR resulted in PNOD and ECOD activities of 1.90 nmol/min/mg·protein and 12.39 pmol/min/mg·protein, which were 1.6- and 1.5-fold of that catalyzed by HaCYP6B7 expressed alone, respectively. Furthermore, microsomes of pPICZA-HaCYP6B7-HaCPR-GS115 had higher detoxification activity than that of pPICZA-HaCYP6B7-GS115 to fenvalerate, but not chlorpyrifos. The results indicated that co-expression of HaCYP6B7 with conspecific CPR could enhance the detoxification activities to some substrates comparing with expression of HaCYP6B7 alone.

A double-stranded RNA degrading enzyme reduces the efficiency of oral RNA interference in migratory locust

Application of RNA interference (RNAi) for insect pest management is limited by variable efficiency of RNAi in different insect species. In Locusta migratoria, RNAi is highly efficient through injection of dsRNA, but oral delivery of dsRNA is much less effective. Efforts to understand this phenomenon have shown that dsRNA is more rapidly degraded in midgut fluid than in hemolymph due to nuclease enzyme activity. In the present study, we identified and characterized two full-length cDNAs of double-stranded RNA degrading enzymes (dsRNase) from midgut of L. migratoria, which were named LmdsRNase2 and LmdsRNase3. Gene expression analysis revealed that LmdsRNase2 and LmdsRNase3 were predominantly expressed in the midgut, relatively lower expression in gastric caeca, and trace expression in other tested tissues. Incubation of dsRNA in midgut fluid from LmdsRNase3-suppressed larvae or control larvae injected with dsGFP resulted in high levels of degradation; however, dsRNA incubated in midgut fluid from LmdsRNase2-suppressed larvae was more stable, indicating LmdsRNase2 is responsible for dsRNA degradation in the midgut. To verify the biological function of LmdsRNase2 in vivo, nymphs were injected with dsGFP, dsLmdsRNase2 or dsLmdsRNase3 and chitinase 10 (LmCht10) or chitin synthase 1 (LmCHS1) dsRNA were orally delivered. Mortality associated with reporter gene knockdown was observed only in locusts injected with dsLmdsRNase2 (48% and 22%, for dsLmCht10 and dsLmCHS1, respectively), implicating LmdsRNase2 in reducing RNAi efficiency. Furthermore, recombinantly expressed LmdsRNase2 fusion proteins degraded dsRNA rapidly, whereas LmdsRNase3 did not. These results suggest that rapid degradation of dsRNA by dsRNase2 in the midgut is an important factor causing low RNAi efficiency when dsRNA is orally delivered in the locust.

The place of James Arnott (1797-1883) in the development of local anaesthesia in dentistry

Dental disease in the form of caries and abscesses has been known since antiquity. Before the advent of anaesthesia, operations upon the mouth were painful. The introduction of general anaesthesia in the form of ether and chloroform seemed to provide a solution, but there was an unacceptable level of mortality. James Arnott introduced local anaesthesia by means of freezing with ice, which he considered safer. He waged a long campaign and his method received recognition and was used in France and the USA. His method stimulated the development of pharmacological anaesthesia.

Molecular Mechanism of Action and Selectivity of Sodium Ch annel Blocker Insecticides

Sodium channel blocker insecticides (SCBIs) are a relatively new class of insecticides that are represented by two commercially registered compounds, indoxacarb and metaflumizone. SCBIs, like pyrethroids and DDT, target voltage-gated sodium channels (VGSCs) to intoxicate insects. In contrast to pyrethroids, however, SCBIs inhibit VGSCs at a distinct receptor site that overlaps those of therapeutic inhibitors of sodium channels, such as local anesthetics, anticonvulsants and antiarrhythmics. This review will recount the development of the SCBI insecticide class from its roots as chitin synthesis inhibitors, discuss the symptoms of poisoning and evidence supporting inhibition of VGSCs as their mechanism of action, describe the current model for SCBI-induced inhibition of VGSCs, present a model for the receptor for SCBIs on VGSCs, and highlight differences between data collected from mammalian and insect experimental models.

Inhibition of Kv channel expression by NSAIDs depolarizes membrane potential and inhibits cell migration by disrupting calpain signaling

Clinical use of non-steroidal anti-inflammatory drugs (NSAIDs) is well known to cause gastrointestinal ulcer formation via several mechanisms that include inhibiting epithelial cell migration and mucosal restitution. The drug-affected signaling pathways that contribute to inhibition of migration by NSAIDs are poorly understood, though previous studies have shown that NSAIDs depolarize membrane potential and suppress expression of calpain proteases and voltage-gated potassium (Kv) channel subunits. Kv channels play significant roles in cell migration and are targets of NSAID activity in white blood cells, but the specific functional effects of NSAID-induced changes in Kv channel expression, particularly on cell migration, are unknown in intestinal epithelial cells. Accordingly, we investigated the effects of NSAIDs on expression of Kv1.3, 1.4, and 1.6 in vitro and/or in vivo and evaluated the functional significance of loss of Kv subunit expression. Indomethacin or NS-398 reduced total and plasma membrane protein expression of Kv1.3 in cultured intestinal epithelial cells (IEC-6). Additionally, depolarization of membrane potential with margatoxin (MgTx), 40mM K(+), or silencing of Kv channel expression with siRNA significantly reduced IEC-6 cell migration and disrupted calpain activity. Furthermore, in rat small intestinal epithelia, indomethacin and NS-398 had significant, yet distinct, effects on gene and protein expression of Kv1.3, 1.4, or 1.6, suggesting that these may be clinically relevant targets. Our results show that inhibition of epithelial cell migration by NSAIDs is associated with decreased expression of Kv channel subunits, and provide a mechanism through which NSAIDs inhibit cell migration and may contribute to NSAID-induced gastrointestinal (GI) toxicity.

Molecular biology of insect sodium channels and pyrethroid resistance

Voltage-gated sodium channels are essential for the initiation and propagation of the action potential in neurons and other excitable cells. Because of their critical roles in electrical signaling, sodium channels are targets of a variety of naturally occurring and synthetic neurotoxins, including several classes of insecticides. This review is intended to provide an update on the molecular biology of insect sodium channels and the molecular mechanism of pyrethroid resistance. Although mammalian and insect sodium channels share fundamental topological and functional properties, most insect species carry only one sodium channel gene, compared to multiple sodium channel genes found in each mammalian species. Recent studies showed that two posttranscriptional mechanisms, alternative splicing and RNA editing, are involved in generating functional diversity of sodium channels in insects. More than 50 sodium channel mutations have been identified to be responsible for or associated with knockdown resistance (kdr) to pyrethroids in various arthropod pests and disease vectors. Elucidation of molecular mechanism of kdr led to the identification of dual receptor sites of pyrethroids on insect sodium channels. Many of the kdr mutations appear to be located within or close to the two receptor sites. The accumulating knowledge of insect sodium channels and their interactions with insecticides provides a foundation for understanding the neurophysiology of sodium channels in vivo and the development of new and safer insecticides for effective control of arthropod pests and human disease vectors.

Expression of pleiotrophin, an important regulator of cell migration, is inhibited in intestinal epithelial cells by treatment with non-steroidal anti-inflammatory drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most widely used drugs for the suppression of inflammation and pain. However, the analgesic properties of NSAIDs are also associated with significant negative side effects, most notably in the gastrointestinal (GI) tract. Increasingly, evidence indicates that the ulcerogenic properties of some NSAIDs are not exclusively the result of inhibition of cyclooxygenase isoforms in the GI tract, and other mechanisms, including inhibition of cell migration and epithelial restitution, are being explored. Recently, microarray analysis was used to identify potential novel targets of NSAID activity in intestinal epithelial cells. Treated cells exhibited significant reductions in the gene expression of pleiotrophin (PTN), a cytokine and growth factor known to participate in angiogenesis and bone growth. This report aimed to confirm the microarray results reported previously, and to measure protein expression of PTN in intestinal epithelial cells. Furthermore, we also examined the effects of exogenous PTN on cell migration in the presence and absence of either NSAIDs with variable ulcerogenic potential or PTN-specific siRNA. Our results demonstrated that indomethacin and NS-398, two NSAIDs with ulcerogenic potential significantly decrease both gene and protein expressions of PTN in IEC-6 cells and protein expression in IEC-6-Cdx2 cells. Additionally, cell migration experiments with PTN siRNA showed that PTN is an important mediator of IEC-6 cell migration, and addition of exogenous PTN partially restores the deficits in cell migration caused by treatment with indomethacin and NS-398. Finally, measurement of PTN protein expression in the GI tract of horses treated with phenylbutazone showed that PTN expression is reduced by NSAIDs in vivo. Our results show that PTN is an important mediator of cell migration in IEC-6 cells, and PTN is a potential target through which NSAIDs may inhibit cell migration, epithelial restitution, and wound healing in the GI tract.

Non-steroidal anti-inflammatory drugs inhibit calpain activity and membrane localization of calpain 2 protease

Non-steroidal anti-inflammatory drugs (NSAIDs) are used frequently worldwide for the alleviation of pain despite their capacity to cause adverse gastrointestinal (GI) side effects. GI toxicity, once thought to be the result of non-specific inhibition of cyclooxegenase (COX) enzymes, is now hypothesized to have multiple other causes that are COX independent. In particular, NSAIDs inhibit intestinal epithelial restitution, the process by which barrier function in intestinal mucosa is restored at sites of epithelial wounds within hours through cell spreading and migration. Accordingly, recent evidence indicates that the expression of calpain proteases, which play a key role in cell migration, is decreased by NSAIDs that inhibit cell migration in intestinal epithelial cells (IEC). Here, we examine the effect of NSAIDs on calpain activity and membrane expression in IEC-6 cells. Indomethacin, NS-398, and SC-560 inhibited calpain activity and decreased expression of calpain 2 in total membrane fractions and in plasma membranes involved in cell attachment to the substrate. Additionally, we demonstrated that inhibition of calpain activity by NSAIDs or ALLM, a calpain inhibitor, limits cell migration and in vitro wound healing of IEC-6 cells. Our results indicate that NSAIDs may inhibit cell migration by decreasing calpain activity and membrane-associated expression of calpain 2. Our results provide valuable insight into the mechanisms behind NSAID-induced GI toxicity and provide a potential pathway through which these negative side effects can be avoided in future members of the NSAID class.

Immunization of puppies in the presence of maternally derived antibodies against canine distemper virus

Vaccination of dams with modified-live canine distemper virus (CDV) vaccines will elicit high concentrations of colostral antibody, that although vital for protection of the pup during the first weeks of life, can interfere with active vaccination against the virus. In the present study, 12 pups, 7-9 weeks of age, with maternally derived immunity to CDV, were vaccinated with a canarypox-vectored CDV vaccine. These pups were protected against intravenous challenge with CDV. Three littermate pups that were unvaccinated all developed clinical signs of infection after challenge, and two of these control pups died.

Depolarization and decreased surface expression of K+ channels contribute to NSAID-inhibition of intestinal restitution

Non-steroidal anti-inflammatory drugs (NSAIDs) contribute to gastrointestinal ulcer formation by inhibiting epithelial cell migration and mucosal restitution; however, the drug-affected signaling pathways are poorly defined. We investigated whether NSAID inhibition of intestinal epithelial migration is associated with depletion of intracellular polyamines, depolarization of membrane potential (E(m)) and altered surface expression of K(+) channels. Epithelial cell migration in response to the wounding of confluent IEC-6 and IEC-Cdx2 monolayers was reduced by indomethacin (100 microM), phenylbutazone (100 microM) and NS-398 (100 microM) but not by SC-560 (1 microM). NSAID-inhibition of intestinal cell migration was not associated with depletion of intracellular polyamines. Treatment of IEC-6 and IEC-Cdx2 cells with indomethacin, phenylbutazone and NS-398 induced significant depolarization of E(m), whereas treatment with SC-560 had no effect on E(m). The E(m) of IEC-Cdx2 cells was: -38.5+/-1.8 mV under control conditions; -35.9+/-1.6 mV after treatment with SC-560; -18.8+/-1.2 mV after treatment with indomethacin; and -23.7+/-1.4 mV after treatment with NS-398. Whereas SC-560 had no significant effects on the total cellular expression of K(v)1.4 channel protein, indomethacin and NS-398 decreased not only the total cellular expression of K(v)1.4, but also the cell surface expression of both K(v)1.4 and K(v)1.6 channel subunits in IEC-Cdx2. Both K(v)1.4 and K(v)1.6 channel proteins were immunoprecipitated by K(v)1.4 antibody from IEC-Cdx2 lysates, indicating that these subunits co-assemble to form heteromeric K(v) channels. These results suggest that NSAID inhibition of epithelial cell migration is independent of polyamine-depletion, and is associated with depolarization of E(m) and decreased surface expression of heteromeric K(v)1 channels.

State-dependent block of rat Nav1.4 sodium channels expressed in xenopus oocytes by pyrazoline-type insecticides

Insecticidal pyrazolines inhibit voltage-sensitive sodium channels of both insect and mammalian neurons in a voltage-dependent manner. Studies on the effects of pyrazoline insecticides on mammalian sodium channels have been limited to experimentation on the tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) sodium channel populations of rat dorsal root ganglion (DRG) neurons. In this study, we examined the effects of the insecticidal pyrazolines indoxacarb, the N-decarbomethoxyllated metabolite of indoxacarb (DCJW), and RH 3421 on rat Na(v)1.4 sodium channels expressed in Xenopus laevis oocytes using the two-electrode voltage clamp technique. Both DCJW and RH 3421 were ineffective inhibitors of rat Na(v)1.4 sodium channels at a membrane potential of -120 mV, but depolarization to -60 mV or -30 mV during insecticide exposure resulted in substantial block. Inhibition by pyrazoline insecticides was nearly irreversible with washout, but repolarization of the membrane relieved block. DCJW and RH 3421 also caused hyperpolarizing shifts in the voltage dependence of slow inactivation without affecting the voltage dependence of activation or fast inactivation. These results suggest that DCJW and RH 3421 interact specifically with the slow inactivated state of the sodium channel. Indoxacarb did not cause block at any potential, yet it interfered with the ability of DCJW, but not RH 3421, to inhibit sodium current. Phenytoin, an anticonvulsant, reduced the efficacy of both DCJW and RH 3421. These data imply that the binding site for pyrazoline insecticides overlaps with that for therapeutic sodium channel blockers.

A meta-analytic investigation of linkage and association of common leptin receptor (LEPR) polymorphisms with body mass index and waist circumference

METHODS

We analyzed data pooled from nine studies on the human leptin receptor (LEPR) gene for the association of three alleles (K109R, Q223R and K656N) of LEPR with body mass index (BMI; kg/m(2)) and waist circumference (WC). A total of 3263 related and unrelated subjects from diverse ethnic backgrounds including African-American, Caucasian, Danish, Finnish, French Canadian and Nigerian were studied. We tested effects of individual alleles, joint effects of alleles at multiple loci, epistatic effects among alleles at different loci, effect modification by age, sex, diabetes and ethnicity, and pleiotropic genotype effects on BMI and WC.

RESULTS

We found that none of the effects were significant at the 0.05 level. Heterogeneity tests showed that the variations of the non-significant effects are within the range of sampling variation.

CONCLUSIONS

We conclude that, although certain genotypic effects could be population-specific, there was no statistically compelling evidence that any of the three LEPR alleles is associated with BMI or WC in the overall population.