Development of an on-site diagnostic LAMP assay for rapid differentiation of the invasive pest Phthorimaea absoluta (Meyrick) using insect tissues

BACKGROUND

The tomato leafminer, Phthorimaea absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a destructive invasive pest that originated in South America and has spread within China since 2017. A rapid method for on-site identification of P. absoluta is urgently needed for interception of this pest across China.

RESULTS

We developed a loop-mediated isothermal amplification (LAMP) technique to differentiate P. absoluta from Liriomyza sativae, Chromatomyia horticola, and Phthorimaea operculella using extracted genomic DNA, which was then refined to create an on-site LAMP diagnostic method that can be performed under field conditions without the need for laboratory equipment.

CONCLUSION

In the present research, we developed an on-site diagnostic method for rapid differentiation of P. absoluta from other insects with similar morphology or damage characteristics in China. © 2024 Society of Chemical Industry.

Dual mutations in the whitefly nicotinic acetylcholine receptor β1 subunit confer target-site resistance to multiple neonicotinoid insecticides

Neonicotinoid insecticides, which target insect nicotinic acetylcholine receptors (nAChRs), have been widely and intensively used to control the whitefly, Bemisia tabaci, a highly damaging, globally distributed, crop pest. This has inevitably led to the emergence of populations with resistance to neonicotinoids. However, to date, there have been no reports of target-site resistance involving mutation of B. tabaci nAChR genes. Here we characterize the nAChR subunit gene family of B. tabaci and identify dual mutations (A58T&R79E) in one of these genes (BTβ1) that confer resistance to multiple neonicotinoids. Transgenic D. melanogaster, where the native nAChR Dβ1 was replaced with BTβ1A58T&R79E, were significantly more resistant to neonicotinoids than flies where Dβ1 were replaced with the wildtype BTβ1 sequence, demonstrating the causal role of the mutations in resistance. The two mutations identified in this study replace two amino acids that are highly conserved in >200 insect species. Three-dimensional modelling suggests a molecular mechanism for this resistance, whereby A58T forms a hydrogen bond with the R79E side chain, which positions its negatively-charged carboxylate group to electrostatically repulse a neonicotinoid at the orthosteric site. Together these findings describe the first case of target-site resistance to neonicotinoids in B. tabaci and provide insight into the molecular determinants of neonicotinoid binding and selectivity.

Both symbionts and environmental factors contribute to shape the microbiota in a pest insect, Sogatella furcifera

Introduction

Bacterial symbionts are prevalent in arthropods globally and play a vital role in the fitness and resistance of hosts. While several symbiont infections have been identified in the white-backed planthopper Sogatella furcifera, the impact of environmental factors on the microbiota within S. furcifera remains elusive.

Methods

In this study, a total of 142 S. furcifera individuals from 18 populations were collected from 14 locations across six countries (China, Thailand, Myanmar, Cambodia, Vietnam, and Laos) analyzed with 2bRAD-M sequencing, to examine the effects of symbionts on the microbiota in the S. furcifera population, as well as the vital effects of environmental factors on the bacterial communities.

Results and discussion

Based on the results, in S. furcifera, the presence of symbionts Wolbachia and Cardinium negatively influenced the abundance of other bacteria, including Enterobacter, Acinetobacter, and Lysinibacillus, while Wolbachia infection significantly decreased the diversity of the microbial community. Moreover, several environmental factors, including longitude, latitude, temperature, and precipitation, affected the abundance of symbionts and microbiota diversity in S. furcifera. These results collectively highlight the vital role of Wolbachia in S. furcifera microbiota, as well as the intricate effects of environmental factors on the bacterial communities of S. furcifera.

Prevalence, evolution, replication and transmission of H3N8 avian influenza viruses isolated from migratory birds in eastern China from 2017 to 2021

The continued evolution and emergence of novel influenza viruses in wild and domestic animals poses an increasing public health risk. Two human cases of H3N8 avian influenza virus infection in China in 2022 have caused public concern regarding the risk of transmission between birds and humans. However, the prevalence of H3N8 avian influenza viruses in their natural reservoirs and their biological characteristics are largely unknown. To elucidate the potential threat of H3N8 viruses, we analyzed five years of surveillance data obtained from an important wetland region in eastern China and evaluated the evolutionary and biological characteristics of 21 H3N8 viruses isolated from 15,899 migratory bird samples between 2017 and 2021. Genetic and phylogenetic analyses showed that the H3N8 viruses circulating in migratory birds and ducks have evolved into different branches and have undergone complicated reassortment with viruses in waterfowl. The 21 viruses belonged to 12 genotypes, and some strains induced body weight loss and pneumonia in mice. All the tested H3N8 viruses preferentially bind to avian-type receptors, although they have acquired the ability to bind human-type receptors. Infection studies in ducks, chickens and pigeons demonstrated that the currently circulating H3N8 viruses in migratory birds have a high possibility of infecting domestic waterfowl and a low possibility of infecting chickens and pigeons. Our findings imply that circulating H3N8 viruses in migratory birds continue to evolve and pose a high infection risk in domestic ducks. These results further emphasize the importance of avian influenza surveillance at the wild bird and poultry interface.

Heterogeneous distribution of Cardinium in whitefly populations is associated with host nuclear genetic background

Inherited bacterial symbionts are very common in arthropods, but infection frequency can vary widely among populations. Experiments and interpopulation comparisons suggest that host genetic background might be important in explaining this variation. Our extensive field investigation showed that the infection pattern of the facultative symbiont Cardinium was heterogeneous across geographical populations of the invasive whitefly Bemisia tabaci Mediterranean (MED) in China, with genetic nuclear differences evident in 2 of the populations: 1 with a low infection rate (SD line) and 1 with a high infection rate (HaN line). However, whether the heterogeneous frequency of Cardinium is associated with the host genetic background remains poorly understood. Here, we compared the fitness of the Cardinium-infected and uninfected sublines with similar nuclear genetic backgrounds from SD and HaN lines, respectively, and further determine whether host extranuclear or nuclear genotype influenced the Cardinium-host phenotype by performing 2 new introgression series of 6 generations between SD and HaN lines (i.e., Cardinium-infected females of SD were backcrossed with uninfected males of HaN, and vice versa). The results showed that Cardinium provides marginal fitness benefits in the SD line, whereas Cardinium provides strong fitness benefits in the HaN line. Further, both Cardinium and the Cardinium-host nuclear interaction influence the fecundity and pre-adult survival rate of B. tabaci, whereas the extranuclear genotype does not. In conclusion, our results provide evidence that Cardinium-mediated fitness effects were closely associated with the host genetic background, which provides a fundamental basis for understanding the mechanism underlying the heterogeneous distribution of Cardinium in B. tabaci MED populations across China.

The Genetic Diversity of White-Backed Planthoppers (Sogatella furcifera) between Myanmar and Yunnan Province of China

In order to clarify the migration route and the source of white-backed planthopper (WBPH) (Sogatella furcifera) between Myanmar and Yunnan Province, China, we collected six populations throughout Myanmar and five populations around the border areas in Yunnan Province, China. A total of 790 base pairs in the mtDNA COI genes from 416 individuals were obtained. A total of 43 haplotypes were identified, among which 37 were unique haplotypes, and the remaining 6 were shared among different populations. Two common shared haplotypes (H_1 and H_2) had a widespread distribution in all populations and accounted for 88.8% of the total haplotype frequency, suggesting a high-level gene flow among the Myanmar and Yunnan populations. Bayesian skyline plot (BSP) analysis results indicated that the effective population size of WBPH expanded between about 10,000 and 7000 years ago, and S. furcifera might follow the post-LGM (Last Glacial Maximum) expansion pattern. Based on the total migrant (Nem) value, it can be deduced that north and northeast Myanmar were the primary migration sources for WBPH populations in the southwest and south Yunnan regions. This study aims to contribute to the sustainable regional management of this important rice pest and provide new insights into the genetic diversity of WBPH in Southeast Asia.

Pyrifluquinazon baseline susceptibility and inhibition of Tomato chlorosis virus transmission by Bemisia tabaci

BACKGROUND

Tomato chlorosis virus (ToCV) is associated with tomato yellow leaf disorder diseases in more than 20 countries. ToCV can be transmitted in a semipersistent manner by whitefly vectors such as Bemisia tabaci. Controlling the vector pests by using chemical insecticides is an efficient and effective approach to reduce and interrupt the virus transmission. Pyrifluquinazon is a new pyridine azomethine derivative, showing insecticidal toxicity to sucking pests by disturbing their feeding behavior. However, limited attention has been paid to the performance of pyrifluquinazon against B. tabaci and ToCV transmission.

RESULT

This study showed the lethal concentration of 50% (LC50 ) values of pyrifluquinazon to 22 B. tabaci field populations ranged from 0.54 to 2.44 mg L-1 , and the baseline susceptibility of B. tabaci to pyrifluquinazon was 1.24 mg L-1 with a 95% confidence limit of 0.35-1.85 mg L-1 . Pyrifluquinazon and afidopyropen did not show cross-resistance to dinotefuran and pymetrozine in B. tabaci, which both inhibited the feeding activities of B. tabaci. The antifeedant concentration of 50% (AFC50 ) values at 48 h were 0.70 mg L-1 for pyrifluquinazon and 2.13 mg L-1 for afidopyropen. Foliar application of pyrifluquinazon and afidopyropen reduced the ToCV transmission by 40.91% and 33.33%, respectively and significantly decreased the ToCV loads in tomato plants under laboratory conditions.

CONCLUSION

These results provided new information about the effects of modulators of the vanilloid-type transient receptor potential channel on the toxicity to B. tabaci and inhibition of ToCV transmission. © 2023 Society of Chemical Industry.

Infection density pattern of Cardinium affects the responses of bacterial communities in an invasive whitefly under heat conditions

Communities of bacteria, especially symbionts, are vital for the growth and development of insects and other arthropods, including Bemisia tabaci Mediterranean (MED), a destructive and invasive insect pest. However, the infection density patterns and influence factors of bacteria in whiteflies, which mainly include symbionts, remain largely unclear. To reveal the different density patterns of Cardinium in B. tabaci MED populations and the impacts of high temperatures on whiteflies with different Cardinium density infection patterns, 2 isofemale lines isolated from B. tabaci MED from the same geographical population of China and from B. tabaci MED collected from other countries and locations were examined using several techniques and methods, including fluorescence in situ hybridization (FISH), quantitative real-time polymerase chain reaction (qPCR), 16S rRNA gene sequencing, and 2b-RAD sequencing. The results showed that there were 2 different infection density patterns of Cardinium in B. tabaci MED (including 1 high-density pattern and 1 low-density pattern). For whiteflies with low-density Cardinium, conventional PCR could not detect Cardinium, but the other techniques confirmed that there was a low level of Cardinium within hosts. High temperature significantly decreased the diversity of bacterial communities: the relative titer of Cardinium increased but the density of Rickettsia decreased in the isofemale line with high-density Cardinium. However, high temperature did not influence the diversity and symbiont density in the line with low-density Cardinium. Moreover, high temperature influenced the functions of bacterial communities in whiteflies with high-density Cardinium but did not affect the bacterial functions in whiteflies with low-density Cardinium. Our results provide novel insights into the complex associations between symbionts and host insects.

Novel Avian Influenza Virus (H5N1) Clade 2.3.4.4b Reassortants in Migratory Birds, China

Two novel reassortant highly pathogenic avian influenza viruses (H5N1) clade 2.3.4.4b.2 were identified in dead migratory birds in China in November 2021. The viruses probably evolved among wild birds through different flyways connecting Europe and Asia. Their low antigenic reaction to vaccine antiserum indicates high risks to poultry and to public health.

Cardinium infection alters cotton defense and detoxification metabolism of its whitefly host

Field monitoring revealed that the infection ratio of the bacterial symbiont Cardinium in the whitefly (Bemisia tabaci MED) was relatively low in northern China. However, the role of this symbiont and the symbiont-whitefly-host plant interaction mechanism are poorly understood. We investigated the influence of Cardinium on the competitiveness of the host whitefly and the physiological interaction between the host plants and host whiteflies. Cardinium-infected whiteflies were displaced by uninfected whiteflies after 5 generations, which showed that Cardinium infection reduced whitefly competitiveness. The defense response genes of cotton significantly decreased under infestation by infected whiteflies compared to uninfected whiteflies. The expression of detoxification metabolism genes, especially the uridine 5'-diphospho-glucuronyltransferase and P450 genes, in infected whiteflies significantly decreased. These results demonstrated that Cardinium could inhibit the defense response of the host plant and decrease the detoxification metabolism ability of the host whitefly. The reduced competitiveness of infected whiteflies may be associated with the inhibition of the whitefly detoxification metabolism by Cardinium, resulting in the reduced performance of infected whiteflies. However, Cardinium infection can suppress plant defenses, which may benefit both infected and uninfected whiteflies when they coexist. This research illustrates the symbiont-whitefly-host plant interaction mechanism and the population dynamics of the whitefly.

Genome-Wide Identification and Expression Analysis of the Cytochrome P450 Gene Family in Bemisia tabaci MED and Their Roles in the Insecticide Resistance

The whitefly, Bemisia tabaci MED (Hemiptera: Aleyrodidae), is an omnivorous agricultural pest, which causes huge economic losses to agriculture and is highly resistant to many pesticides. The overexpression of cytochrome P450 may play an important role in host adaptation and insecticide resistance in B. tabaci MED. Therefore, the present study systematically analyzed the cytochrome P450 gene family at the genome-wide level to understand its function in B. tabaci MED. Our analysis identified 58 cytochrome P450 genes in B. tabaci MED, among which 24 were novel. Phylogenetic analysis revealed broad functional and species-specific diversification in B. tabaci MED P450, suggesting the role of multiple P450 genes in detoxifying. Reverse transcription-real time quantitative PCR (RT-qPCR) showed that CYP4CS2, CYP4CS5, CYP4CS6, CYP4CS8, CYP6DW4, CYP6DW5, CYP6DW6, CYP6DZ8, and CYP6EN1 genes increased significantly after two days of exposure to imidacloprid. Interestingly, all nine genes belonged to the CYP4 and CYP6 families. A decrease in the expression of five genes (CYP6DW4, CYP6DW5, CYP6DW6, CYP6DZ8, and CYP4CS6) via RNA interference (RNAi) resulted in a significant increase in the mortalities of whiteflies when exposed to imidacloprid. These results indicate that the overexpression of the P450 genes may play an essential role in imidacloprid tolerance of B. tabaci MED. Thus, the present study provides basic information on P450 genes in B. tabaci MED, which will further help elucidate the insecticide resistance mechanism in the agricultural pest whitefly.

Ecological Factors Associated with the Distribution of Bemisia tabaci Cryptic Species and Their Facultative Endosymbionts

The sweetpotato whitefly, Bemisia tabaci species complex, comprises at least 44 morphologically indistinguishable cryptic species, whose endosymbiont infection patterns often varied at the spatial and temporal dimension. However, the effects of ecological factors (e.g., climatic or geographical factors) on the distribution of whitefly and the infection frequencies of their endosymbionts have not been fully elucidated. We, here, analyzed the associations between ecological factors and the distribution of whitefly and their three facultative endosymbionts (Candidatus Cardinium hertigii, Candidatus Hamiltonella defensa, and Rickettsia sp.) by screening 665 individuals collected from 29 geographical localities across China. The study identified eight B. tabaci species via mitochondrial cytochrome oxidase I (mtCOI) gene sequence alignment: two invasive species, MED (66.9%) and MEAM1 (12.2%), and six native cryptic species (20.9%), which differed in distribution patterns, ecological niches, and high suitability areas. The infection frequencies of the three endosymbionts in different cryptic species were distinct and multiple infections were relatively common in B. tabaci MED populations. Furthermore, the annual mean temperature positively affected Cardinium sp. and Rickettsia sp. infection frequencies in B. tabaci MED but negatively affected the quantitative distribution of B. tabaci MED, which indicates that Cardinium sp. and Rickettsia sp. maybe play a crucial role in the thermotolerance of B. tabaci MED, although the host whitefly per se exhibits no resistance to high temperature. Our findings revealed the complex effects of ecological factors on the expansion of the invasive whitefly.

[Forsythiaside B inhibits cerebral ischemia/reperfusion-induced oxidative stress injury in mice via the AMPK/DAF-16/FOXO3 pathway]

OBJECTIVE

To study the protective effect of forsythiaside B (FB) against cerebral oxidative stress injury induced by cerebral ischemia/reperfusion (I/R) in mice and explore the underlying mechanism.

METHODS

Ninety C57BL/6 mice were randomized into sham-operated group, middle cerebral artery occlusion (MCAO) model group, and low-, medium and highdose (10, 20, and 40 mg/kg, respectively) FB groups. The expression levels of MDA, ROS, PCO, 8-OHdG, SOD, GSTα4, CAT and GPx in the brain tissue of the mice were detected using commercial kits, and those of AMPK, P-AMPK, DAF-16, FOXO3 and P-FOXO3 were detected with Western blotting. Compound C (CC), an AMPK inhibitor, was used to verify the role of the AMPK pathway in mediating the therapeutic effect of FB. In another 36 C57BL/6 mice randomized into 4 sham-operated group, MCAO model group, FB (40 mg/kg) treatment group, FB+CC (10 mg/kg) treatment group, TTC staining was used to examine the volume of cerebral infarcts, and the levels of ROS and SOD in the brain were detected; the changes in the protein expressions of AMPK, P-AMPK, DAF-16, FOXO3 and P-FOXO3 in the brain tissue were detected using Western blotting.

RESULTS

In mice with cerebral IR injury, treatment with FB significantly reduced the levels of ROS, MDA, PCO and 8-OHdG, increased the activities of antioxidant enzymes SOD, GSTα4, CAT and GPx, and enhanced phosphorylation of AMPK and FOXO3 and DAF-16 protein expression in the brain tissue (P < 0.01). Compared with FB treatment alone, the combined treatment with FB and CC significantly reduced phosphorylation of AMPK and FOXO3, lowered expression of DAF-16 and SOD activity, and increased cerebral infarction volume and ROS level in the brain tissue of the mice (P < 0.01).

CONCLUSION

FB inhibits oxidative stress injury caused by cerebral I/R in mice possibly by enhancing AMPK phosphorylation, promoting the downstream DAF-16 protein expression and FOXO3 phosphorylation, increasing the expression of antioxidant enzymes, and reducing ROS level in the brain tissue.

Expression profile of CYP402C1 and its role in resistance to imidacloprid in the whitefly, Bemisia tabaci

Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a cosmopolitan insect pest causing serious damage to crop production. Cytochromes P450 (CYPs) of B. tabaci are widely known to be involved in the metabolic resistance to a variety of insecticides, continuously increasing the difficulty in controlling this pest. In this study, four P450 genes (CYP6CM1, CYP6CX1, CYP6CX3, and CYP402C1) in B. tabaci exhibited correlations with the resistance to imidacloprid. We have focused on trying to understand the function and metabolism capacity of CYP402C1. The expression profiles of CYP402C1 were examined by reverse transcription quantitative real-time PCR and fluorescence in situ hybridizations. Its role in resistance to imidacloprid was investigated by RNA interference, transgenic Drosophila melanogaster, and heterologous expression. The results showed that CYP402C1 was highly expressed in the active feeding stages of B. tabaci, such as nymphs and female adults. CYP402C1 was mainly expressed in midguts of nymphs and adults, especially in the filter chamber. Knockdown of CYP402C1 significantly decreased the resistance of B. tabaci to imidacloprid by 3.96-fold (50% lethal concentration: 186.46 versus 47.08 mg/L). Overexpression of CYP402C1 in a transgenic D. melanogaster line (Gal4 > UAS-CYP402C1) significantly increased the resistance to imidacloprid from 12.68- to 14.92-fold (129.01 and 151.80 mg/L versus 1925.14 mg/L). The heterologous expression of CYP402C1 showed a metabolism ability of imidacloprid (imidacloprid decreased by 12.51% within 2 h). This study provides new insights for CYP402C1 function in B. tabaci and will help develop new strategies in B. tabaci control and its insecticide resistance.

Resistance to dinotefuran in Bemisia tabaci in China: status and characteristics

BACKGROUND

Bemisia tabaci (Gennadius) is a serious agricultural pest worldwide. Neonicotinoids are the most important new class of synthetic insecticides used in the management of B. tabaci. However, B. tabaci populations have developed resistance to various active ingredients in neonicotinoids following long-term and widespread application.

RESULTS

Dinotefuran exhibited high toxicity against most B. tabaci field populations. One population (Din-R) with a high level of resistance to dinotefuran (255.6-fold) was first identified in the field. The Din-R population exhibited medium to high levels of resistance to all the tested neonicotinoid insecticides and a high level of resistance to spinetoram. Genetic inheritance analysis revealed that resistance to dinotefuran was incompletely recessive and polygenic. The synergist piperonyl butoxide significantly increased the toxicity of dinotefuran to Din-R. P450 activity in the Din-R population was 2.19-fold higher than in the susceptible population. RNA-sequencing analysis showed that 12 P450 genes were significantly upregulated in the Din-R population, of which CYP6DW5, CYP6JM1 and CYP306A1 were found to exhibit more than 3.00-fold higher expression in Din-R when using a reverse transcription quantitative real-time polymerase chain reaction. Expression of eight P450 genes was obviously induced by dinotefuran, and CYP6DW5 showed the highest expression level. After knockdown of CYP6DW5 in Din-R, the toxicity of dinotefuran increased significantly.

CONCLUSION

P450 had a crucial role in dinotefuran resistance in B. tabaci, and CYP6DW5 was involved in the resistance. These results provide important information for the management of resistance in B. tabaci and improve our understanding of the resistance mechanism of dinotefuran. © 2022 Society of Chemical Industry.

Preoperative Rehabilitation Is Feasible in the Weeks Prior to Surgery and Significantly Improves Functional Performance

BACKGROUND

Frailty is a multidimensional state of increased vulnerability. Frail patients are at increased risk for poor surgical outcomes. Prior research demonstrates that rehabilitation strategies deployed after surgery improve outcomes by building strength.

OBJECTIVES

Examine the feasibility and impact of a novel, multi-faceted prehabilitation intervention for frail patients before surgery.

DESIGN

Single arm clinical trial.

SETTING

Veterans Affairs hospital.

PARTICIPANTS

Patients preparing for major abdominal, urological, thoracic, or cardiac surgery with frailty identified as a Risk Analysis Index≥30.

INTERVENTION

Prehabilitation started in a supervised setting to establish safety and then transitioned to home-based exercise with weekly telephone coaching by exercise physiologists. Prehabilitation included (a)strength and coordination training; (b)respiratory muscle training (IMT); (c)aerobic conditioning; and (d)nutritional coaching and supplementation. Prehabilitation length was tailored to the 4-6 week time lag typically preceding each participant's normally scheduled surgery.

MEASUREMENTS

Functional performance and patient surveys were assessed at baseline, every other week during prehabilitation, and then 30 and 90 days after surgery. Within-person changes were estimated using linear mixed models.

RESULTS

43 patients completed baseline assessments; 36(84%) completed a median 5(range 3-10) weeks of prehabilitation before surgery; 32(74%) were retained through 90-day follow-up. Baseline function was relatively low. Exercise logs show participants completed 94% of supervised exercise, 78% of prescribed IMT and 74% of home-based exercise. Between baseline and day of surgery, timed-up-and-go decreased 2.3 seconds, gait speed increased 0.1 meters/second, six-minute walk test increased 41.7 meters, and the time to complete 5 chair rises decreased 1.6 seconds(all P≤0.007). Maximum and mean inspiratory and expiratory pressures increased 4.5, 7.3, 14.1 and 13.5 centimeters of water, respectively(all P≤0.041).

CONCLUSIONS

Prehabilitation is feasible before major surgery and achieves clinically meaningful improvements in functional performance that may impact postoperative outcomes and recovery. These data support rationale for a larger trial powered to detect differences in postoperative outcomes.

Predicting potential global distribution and risk regions for potato cyst nematodes (Globodera rostochiensis and Globodera pallida)

Potato cyst nematodes (PCNs), golden (yellow) cyst nematode (Globodera rostochiensis, gPCN) and pale (white) cyst nematode (G. pallida, pPCN), are important invasive pests in many countries and regions where they can cause significant yield and economic loss for agriculture. Prediction and identification of habitats suitable for PCNs are critical for developing biosecurity strategies, both pre and post border, to maximise the potential for early elimination should an incursion occur. To date, the potential global distribution of PCNs has not been thoroughly studied. Therefore, this study conducted a species distribution model to illustrate the potential global distribution of PCNs and risk regions. In this study, the Maximum Entropy Model (Maxent) associated with the Geographic Information System (GIS) was employed to reveal the potential distribution of the gPCN and pPCN. In addition to bioclimate, soil quality was also included in the model. The global cultivated lands, whether the susceptible hosts were present or not, were used to assess the maximum potential risk regions. The limitation factors for PCNs distribution were also assessed. Results showed that 66% of the global land surface was suitable for gPCN or pPCN or both, and both species can colonise more than 75% of the global cultivated lands. The coldest quarter's mean temperature and precipitation were critical limitations in unsuitable regions. In summary, the global risk maps of PCNs contribute valuable additional information that complements previous national/regional distribution predictions. The results of this distribution research will contribute practical support for decision-makers and practitioners to implement biosecurity strategies from a global perspective, that incorporate prevention or promptly enforce control practices to limit the damage caused by future incursions.

Cytochrome P450 Gene, CYP6CX3, Is Involved in the Resistance to Cyantraniliprole in Bemisia tabaci

Bemisia tabaci is an important agricultural sucking pest, and it develops serious resistance to various insecticides. Although cytochrome P450 was involved in the resistance to cyantraniliprole, limited studies have been conducted on B. tabaci. In the present study, piperonyl butoxide significantly increased the toxicity of cyantraniliprole. P450 activities in two resistant populations were 1.97- and 2.17-fold higher than that in the susceptible population. Among 79 P450 genes, CYP6CX3 expressions in two resistant populations were 3.08- and 3.67-fold higher than that in the susceptible population. When CYP6CX3 was knocked down, the toxicity of cyantraniliprole increased significantly. The LC₅₀ value of cyantraniliprole to the Drosophila melanogaster line overexpressing B. tabaci CYP6CX3 increased 7.34-fold. The content of cyantraniliprole was decreased by 25.74 ± 4.27% after mixing with CYP6CX3 and CPR for 2 h. These results suggested that the overexpression of CYP6CX3 was likely involved in the resistance to cyantraniliprole in B. tabaci.

Genome-Wide Identification and Analysis of the Heat-Shock Protein Gene Superfamily in Bemisia tabaci and Expression Pattern Analysis under Heat Shock

Simple Summary

Bemisia tabaci MED is an invasive pest that had caused considerable economic damage in the past decades. Its successful colonization is closely related to heat-shock proteins (HSPs), which are related to heat resistance. In this study, 33 BtaHsps were identified based on the sequenced genome of B. tabaci MED belonging to six HSP families, among which 22 BtaHsps were newly identified. Analysis of the secondary structure and evolutionary relationship showed that they were all closely related. In addition, BtaHsp90A3 of the HSP90 family was screened by analyzing the expression level changes of these genes under 42 °C heat shock and RNAi was performed on the BtaHsp90A3. The results showed that the silencing of BtaHsp90A3 is closely related to the heat resistance of B. tabaci MED. Taken together, this study conducted an in-depth identification of BtaHsps that clarifies their evolutionary relationships and their response to thermal stress in B. tabaci MED.

Abstract

The thermal tolerance of Bemisia tabaci MED, an invasive whitefly species with worldwide distribution, plays an important role in its ecological adaptation during the invasion process. Heat-shock proteins (HSPs) are closely related to heat resistance. In this study, 33 Hsps (BtaHsps) were identified based on sequenced genome of B. tabaci MED belonging to six HSP families, among which 22 Hsps were newly identified. The secondary structures of a further 22 BtaHsps were also predicted. The results of RT-qPCR showed that heat shock could affect the expression of 14 of the 22 Hsps newly identified in this study. Among them, the expression level of six Hsps increased under 42 °C treatment. As the unstudied gene, BtaHsp90A3 had the highest increase rate. Therefore, BtaHsp90A3 was chosen for the RNAi test, and silencing BtaHsp90A3 by RNAi decreased the survival rate of adult B. tabaci at 42 °C. The results indicated that only a few Hsps were involved in the thermal tolerance of host whitefly although many Hsps would response under heat stress. This study conducted a more in-depth and comprehensive identification that demonstrates the evolutionary relationship of BtaHsps and illustrates the response of BtaHsps under the influence of thermal stress in B. tabaci MED.

Seasonal and Year-Round Distributions of Bactrocera dorsalis (Hendel) and Its Risk to Temperate Fruits under Climate Change

Simple Summary

The oriental fruit fly Bactrocera dorsalis (Hendel) is a pest species in the Tephritidae family that damages many fruits and vegetables. Dispersal of B. dorsalis is mediated by human activities (e.g., trade) and climate change, and it can cause serious damage to crops in newly invaded regions. Previous studies mainly focused on the areas potentially suitable for year-round reproduction, but it is unclear where the seasonal and year-round suitable areas are in the world. We used ecological niche models to predict the potential seasonal and year-round distribution areas of B. dorsalis. Bioclimate factors contributed differently to these two kinds of distributions. In the future, the areas suitable for B. dorsalis will increase, and the range will likely expand northward from existing locations. The spread of B. dorsalis in the seasonally suitable areas could threaten the production of some temperate fruits, including apples, peaches, pears, and oranges.

Abstract

Bactrocera dorsalis (Hendel) is an important pest to fruits and vegetables. It can damage more than 300 plant species. The distribution of B. dorsalis has been expanding owing to international trade and other human activities. B. dorsalis occurrence is strongly related to suitable overwintering conditions and distribution areas, but it is unclear where these seasonal and year-round suitable areas are. We used maximum entropy (MaxEnt) to predict the potential seasonal and year-round distribution areas of B. dorsalis. We also projected suitable habitat areas in 2040 and 2060 under global warming scenarios, such as SSP126 and SSP585. These models achieved AUC values of 0.860 and 0.956 for the seasonal and year-round scenarios, respectively, indicating their good prediction capabilities. The precipitation of the wettest month (Bio13) and the mean diurnal temperature range (Bio2) contributed 83.9% to the seasonal distribution prediction model. Bio2 and the minimum temperature of the coldest month (Bio6) provided important information related to the year-round distribution prediction. In future scenarios, the suitable area of B. dorsalis will increase and the range will expand northward. Four important temperate fruits, namely, apples, peaches, pears, and oranges, will be seriously threatened. The information from this study provides a useful reference for implementing improved population management strategies for B. dorsalis.

Involvement of Laccase2 in Cuticle Sclerotization of the Whitefly, Bemisia tabaci Middle East–Asia Minor 1

Cuticle sclerotization is critical for insect survival. Laccase2 (Lac2) is a phenol oxidase that plays a key role in cuticle formation and pigmentation in a variety of insects. However, the function of Lac2 in whitefly, Bemisia tabaci, remains unclear. In this study, we identified a BtLac2 gene in B. tabaci MEAM1 and found that BtLac2 was expressed in all stages. It was highly expressed in the egg stage, followed by nymph and adult. Moreover, the expression of BtLac2 was higher in the cuticle than in other tissues. Knockdown of BtLac2 in nymphs produced thinner and fragile cuticles, which significantly increased the mortality rate, extended the development duration of nymphs, and decreased the emergence rate of adults. This result demonstrates that BtLac2 plays an important role in the cuticle hardening of B. tabaci and suggests a potential management strategy using RNAi to knock down BtLac2 expression.

Highly Pathogenic Avian Influenza A(H5N8) Clade 2.3.4.4b Viruses in Satellite-Tracked Wild Ducks, Ningxia, China, 2020

During October 2020, we identified 13 highly pathogenic avian influenza A(H5N8) clade 2.3.4.4b viruses from wild ducks in Ningxia, China. These viruses were genetically related to H5N8 viruses circulating mainly in poultry in Europe during early 2020. We also determined movements of H5N8 virus‒infected wild ducks and evidence for spreading of viruses.

Development and External Validation of a Dynamic Nomogram With Potential for Risk Assessment of Ruptured Multiple Intracranial Aneurysms

Background and Purpose

About 20.1% of intracranial aneurysms (IAs) carriers are multiple intracranial aneurysms (MIAs) patients with higher rupture risk and worse prognosis. A prediction model may bring some potential benefits. This study attempted to develop and externally validate a dynamic nomogram to assess the rupture risk of each IA among patients with MIA.

Method

We retrospectively analyzed the data of 262 patients with 611 IAs admitted to the Hunan Provincial People's Hospital between November 2015 and November 2021. Multivariable logistic regression (MLR) was applied to select the risk factors and derive a nomogram model for the assessment of IA rupture risk in MIA patients. To externally validate the nomogram, data of 35 patients with 78 IAs were collected from another independent center between December 2009 and May 2021. The performance of the nomogram was assessed in terms of discrimination, calibration, and clinical utility.

Result

Size, location, irregular shape, diabetes history, and neck width were independently associated with IA rupture. The nomogram showed a good discriminative ability for ruptured and unruptured IAs in the derivation cohort (AUC = 0.81; 95% CI, 0.774–0.847) and was successfully generalized in the external validation cohort (AUC = 0.744; 95% CI, 0.627–0.862). The nomogram was calibrated well, and the decision curve analysis showed that it would generate more net benefit in identifying IA rupture than the “treat all” or “treat none” strategies at the threshold probabilities ranging from 10 to 60% both in the derivation and external validation set. The web-based dynamic nomogram calculator was accessible on https://wfs666.shinyapps.io/onlinecalculator/.

Conclusion

External validation has shown that the model was the potential to assist clinical identification of dangerous aneurysms after longitudinal data evaluation. Size, neck width, and location are the primary risk factors for ruptured IAs.

Up-regulation of calmodulin involved in the stress response to cyantraniliprole in the whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae)

Cyantraniliprole is the first diamide insecticide to have cross-spectrum activity against a broad range of insect orders. The insecticide, like other diamides, selectively acts on ryanodine receptor, destroys Ca²⁺ homeostasis, and ultimately causes insect death. Although expression regulations of genes associated with calcium signaling pathways are known to be involved in the response to diamides, little is known regarding the function of calmodulin (CaM), a typical Ca²⁺ sensor central in regulating Ca²⁺ homeostasis, in the stress response of insects to the insecticide. In this study, we cloned and identified the full-length complementary DNA of CaM in the whitefly, Bemisia tabaci (Gennadius), named BtCaM. Quantitative real-time reverse transcription polymerase chain reaction-based analyses showed that the messenger RNA level of BtCaM was rapidly induced from 1.51- to 2.43-fold by cyantraniliprole during 24 h. Knockdown of BtCaM by RNA interference increased the toxicity of cyantraniliprole in whiteflies by 42.85%. In contrast, BtCaM expression in Sf9 cells significantly increased the cells' tolerance to cyantraniliprole as much as 2.91-fold. In addition, the expression of BtCaM in Sf9 cells suppressed the rapid increase of intracellular Ca²⁺ after exposure to cyantraniliprole, and the maximum amplitude in the Sf9-BtCaM cells was only 34.9% of that in control cells (Sf9-PIZ/V5). These results demonstrate that overexpression of BtCaM is involved in the stress response of B. tabaci to cyantraniliprole through regulation of Ca²⁺ concentration. As CaM is one of the most evolutionarily conserved Ca²⁺ sensors in insects, outcomes of this study may provide the first details of a universal insect response to diamide insecticides.

Emergence, prevalence, and evolution of H5N8 avian influenza viruses in central China, 2020

Highly pathogenic influenza A(H5N8) viruses have caused several worldwide outbreaks in birds and are able cross the species barrier to infect humans, posing a substantial threat to public health. After the first detection of H5N8 viruses in deceased swans in Inner Mongolia, we performed early warning and active monitoring along swan migration routes in central China. We isolated and sequenced 42 avian influenza viruses, including 40 H5N8 viruses, 1 H5N2 virus, and 1 H9N2 virus, in central China. Our H5N8 viruses isolated in swan stopover sites and wintering grounds showed high nucleotide homologies in the whole genome, revealing a common evolutionary source. Phylogenetic analysis revealed that the H5 viruses of clade 2.3.4.4b prevalent in 2020 have further diverged into two sub-clades: b1 and b2. The phylogeographic analysis also showed that the viruses of sub-clade b2 most likely originated from poultry in Russia. Notably, whooper swans were found to be responsible for the introduction of sub-clade b2 viruses in central China; whooper and tundra swans play a role in viral spread in the Yellow River Basin and the Yangtze River Basin, respectively. Our findings highlight swans as an indicator species for transborder spreading and monitoring of the H5N8 virus.

First evidence for thermal tolerance benefits of the bacterial symbiont Cardinium in an invasive whitefly, Bemisia tabaci

BACKGROUD

Cardinium symbiont is a maternally inherited bacterial endosymbiont and widely spreads in arthropods including Bemisia tabaci (Hemiptera: Aleyrodidae). However, the potential role of Cardinium played in the biology of their hosts is largely unknown. In two genetic lines (i.e. LS and SG lines) of B. tabaci MED, collected from different locations in China, we tested the effects of Cardinium on the performance of the host whitefly under a constant high temperature (31 °C) using the age-stage two-sex life table method, and explored the genes influenced by Cardinium-infection by RNA-sequencing.

RESULTS

We found that Cardinium did provide protection of B. tabaci against heat stress under 31 °C. However, there was a significant connection between Cardinium-infection and whitefly genetic backgrounds. Performance revealed that Cardinium infection can increase the longevity of both female and male adults and oviposition periods in both lines, but it also conferred benefits of fecundity and pre-adult period to LS line. Additionally, the population parameters such as intrinsic rate of increase (r), finite rate of increase (λ) and mean generation time (T) demonstrated that Cardinium infection conferred fitness benefits to LS line but not to SG line. Transcriptome analysis indicated that several genes related to homeostasis and metamorphosis such as ubiquitin-related genes were highly expressed in Cardinium-infected B. tabaci.

CONCLUSION

The research provided the first evidence that Cardinium can increase the thermal tolerance of whitefly, which may be associated with host genetic background.

Characterization of the ryanodine receptor gene in Encarsia formosa (Gahan) and its expression profile in response to diamide insecticides

Ryanodine receptors (RyRs) are the targets of diamide insecticides, which have been identified and characterized in a dozen insect pests of Lepidoptera, Hemiptera, Diptera and Coleoptera, but limited attention has been paid to the RyR in parasitoid natural enemies. Without this knowledge, it will hinder our effective and efficient application using both parasitoid natural enemies and diamide insecticides simultaneously in the integrated pest management (IPM). In this study, the full-length cDNA of RyR was cloned from Encarsia formosa (EfRyR), a parasitic wasp used worldwide for the biological control of whitefly. Its expression profile was examined in various tissues of E. formosa adults. The toxicities of four diamide insecticides to E. formosa were measured, and then the expression profile of EfRyR after 12 h and 24 h exposure to the LC₅₀ dosages of diamide insecticides was investigated. The results showed that the full-length cDNA of EfRyR was 16, 778 bp including a 15, 345 bp open reading frame, and two alternative splice (AS) sites. Comparing to its expression in the abdomen, EfRyR was highly expressed in the head (11.9-fold) and the thorax (3.7-fold). The toxicities of four dimide insecticides against E. formosa from low to high were chlorantraniliprole (LC₅₀ = 367.84 mg L^-1), cyantraniliprole (221.72 mg L^-1), cyclaniliprole (51.77 mg L^-1), and tetrachlorantraniliprole (8.35 mg L^-1). The expressions of EfRyR and its variants with AS were significantly increased after E. formosa adults were exposed to different diamide insecticides. This study improves our understanding of the RyR in parasitoid wasps and provides useful information on IPM by using E. formosa.

P–547 Single-cell RNA sequencing identifies molecular regulations associated with poor maturation performance on rescue in vitro matured oocytes

Study question

What is the transcriptome signature associated with rescuein vitro matured (rIVM) oocytes?

Summary answer

GATA–1/CREB1/WNT signaling axis was repressed in rIVM oocytes of poor quality.

What is known already

rIVM aims to produce mature oocytes (MII) for in vitro fertilization (IVF) through IVM of immature oocytes collected from stimulated ovaries. It is less popular due to limited success rate in infertility treatment. Genetic aberrations, cellular stress, and the absence of cumulus cell support in oocytes could account for the failure of rIVM.

Study design, size, duration

We applied single-cell RNA sequencing (scRNA-seq) to capture the transcriptomes of human in vivo (IVO) oocytes (n = 10) from 7 donors and rIVM oocytes (n = 10) from 10 donors, followed by studying the maternal age effect and ovarian responses on rIVM oocyte transcriptomes.

Participants/materials, setting, methods

Human oocytes were collected from donors aged 28–41 years with a body mass index of &lt; 30. RNA extraction, cDNA generation, library construction and sequencing were performed in one preparation. scRNA-seq data were then processed and analyzed. Selected genes in therIVM vs. IVO comparison were validated by quantitative real-time PCR.

Main results and the role of chance

The transcriptome profiles of rIVM/IVO showed distinctive differences. A total of 1559 differentially expressed genes (DEGs, genes with at least two-fold change and adjusted p &lt; 0.05) were found to be enriched in metabolic processes, biosynthesis, and oxidative phosphorylation. Among these DEGs, we identified a repression of WNT/β-catenin signaling in rIVM when compared with IVO oocytes. We found that estradiol level exhibited a significant age-independent correlation with the IVO mature oocyte ratio (MII ratio). rIVM oocytes with higher MII ratio showed over-represented cellular processes such as anti-apoptosis. To further identify targets that contribute to the poor outcomes of rIVM, we compared oocytes collected from young donors with high MII ratio versus donors of advanced maternal age and revealed CREB1was an important regulator in rIVM. Our study identified GATA–1/CREB1/WNT signaling was repressed in both rIVM condition and rIVM oocytes of low-quality.

Limitations, reasons for caution

In the rIVM oocytes of high- and low-quality comparison, the number of samples was limited after data filtering with stringent selection criteria. For the oocyte stage identification, we were unable to predict the presence of oocyte spindle so polar body extrusion was the only indicator.

Wider implications of the findings: This study showed that GATA–1/CREB1/WNT signaling and antioxidant actions were repressed in rIVM condition and was further downregulated in rIVM oocytes of low-quality, providing us the foundation of subsequent follow-up research on human subjects.

Trial registration number

Not applicable

Pan-Genome Analysis of Vibrio cholerae and Vibrio metschnikovii Strains Isolated From Migratory Birds at Dali Nouer Lake in Chifeng, China

Migratory birds are recently recognized as Vibrio disease vectors, but may be widespread transporters of Vibrio strains. We isolated Vibrio cholerae (V. cholerae) and Vibrio metschnikovii (V. metschnikovii) strains from migratory bird epidemic samples from 2017 to 2018 and isolated V. metschnikovii from migratory bird feces in 2019 from bird samples taken from the Inner Mongolia autonomous region of China. To investigate the evolution of these two Vibrio species, we sequenced the genomes of 40 V. cholerae strains and 34 V. metschnikovii strains isolated from the bird samples and compared these genomes with reference strain genomes. The pan-genome of all V. cholerae and V. metschnikovii genomes was large, with strains exhibiting considerable individual differences. A total of 2,130 and 1,352 core genes were identified in the V. cholerae and V. metschnikovii genomes, respectively, while dispensable genes accounted for 16,180 and 9,178 of all genes for the two strains, respectively. All V. cholerae strains isolated from the migratory birds that encoded T6SS and hlyA were non-O1/O139 serotypes without the ability to produce CTX. These strains also lacked the ability to produce the TCP fimbriae nor the extracellular matrix protein RbmA and could not metabolize trimetlylamine oxide (TMAO). Thus, these characteristics render them unlikely to be pandemic-inducing strains. However, a V. metschnikovii isolate encoding the complete T6SS system was isolated for the first time. These data provide new molecular insights into the diversity of V. cholerae and V. metschnikovii isolates recovered from migratory birds.

Highly Pathogenic Avian Influenza A(H5N8) Virus in Swans, China, 2020

In October 2020, highly pathogenic avian influenza A(H5N8) viruses were detected in 2 dead swans in Inner Mongolia, China. Genetic analysis showed that the H5N8 isolates belong to clade 2.3.4.4b and that the isolates cluster with the H5N8 viruses isolated in Eurasia in the fall of 2020.

Synergistic Effects of a Tomato chlorosis virus and Tomato yellow leaf curl virus Mixed Infection on Host Tomato Plants and the Whitefly Vector

In China, Tomato chlorosis virus (ToCV) and Tomato yellow leaf curl virus (TYLCV) are widely present in tomato plants. The epidemiology of these viruses is intimately associated with their vector, the whitefly (Bemisia tabaci MED). However, how a ToCV+TYLCV mixed infection affects viral acquisition by their vector remains unknown. In this study, we examined the growth parameters of tomato seedlings, including disease symptoms and the heights and weights of non-infected, singly infected and mixed infected tomato plants. Additionally, the spatio-temporal dynamics of the viruses in tomato plants, and the viral acquisition and transmission by B. tabaci MED, were determined. The results demonstrated that: (i) ToCV+TYLCV mixed infections induced tomato disease synergism, resulting in a high disease severity index and decreased stem heights and weights; (ii) as the disease progressed, TYLCV accumulated more in upper leaves of TYLCV-infected tomato plants than in lower leaves, whereas ToCV accumulated less in upper leaves of ToCV-infected tomato plants than in lower leaves; (iii) viral accumulation in ToCV+TYLCV mixed infected plants was greater than in singly infected plants; and (iv) B. tabaci MED appeared to have a greater TYLCV, but a lower ToCV, acquisition rate from mixed infected plants compared with singly infected plants. However, mixed infections did not affect transmission by whiteflies. Thus, ToCV+TYLCV mixed infections may induce synergistic disease effects in tomato plants.

Migration of Sogatella furcifera between the Greater Mekong Subregion and northern China revealed by mtDNA and SNP

Background

The white-backed planthopper (WBPH), Sogatella furcifera (Horváth) (Hemiptera, Delphacidae), is a migratory pest of rice in Asia. Shandong Province, in northern China, is located on the migration pathway of WBPH between southern and northeast China. The potential sources of WBPH in northern China are poorly understood. We studied the sources of WBPH in Shandong Province by determining the population genetic structure of WBPH in 18 sites distributed in Shandong and in six regions of the Greater Mekong Subregion (GMS). We used mitochondrial gene and single-nucleotide polymorphism (SNP) markers for analysis.

Results

All of the WBPH populations studied in the seven regions had low genetic diversity. Pairwise F_ST values based on mtDNA ranged from − 0.061 to 0.285, while F_ST based on SNP data ranged from − 0.007 to 0.009. These two molecular markers revealed that 4.40% (mtDNA) and 0.19% (SNP) genetic variation could be explained by the interpopulation variation, while the rest came from intrapopulation variation. The populations in the seven geographic regions comprised four hypothetical genetic clusters (K = 4) not associated with geographic location. Eighty-four of 129 individuals distributed across the given area were designated as recent migrants or of admixed ancestry. Although the substantial migration presented, a weak but significant correlation between genetic and geographic distances was found (r = 0.083, P = 0.004).

Conclusion

The Greater Mekong Subregion was the main genetic source of WBPH in Shandong, while other source populations may also exist. The genetic structure of WBPH is shaped by both migration and geographic barriers. These results help clarify the migration route and the source of WBPH in northern China.

Optimizing Sample Size for Population Genomic Study in a Global Invasive Lady Beetle, Harmonia Axyridis

Finding optimal sample sizes is critical for the accurate estimation of genetic diversity of large invasive populations. Based on previous studies, we hypothesized that a minimal sample size of 3-8 individuals is sufficient to dissect the population architecture of the harlequin lady beetle, Harmonia axyridis, a biological control agent and an invasive alien species. Here, equipped with a type IIB endonuclease restriction site-associated (2b-RAD) DNA sequencing approach, we identified 13,766 and 13,929 single nucleotide polymorphisms (SNPs), respectively, among native and invasive H. axyridis populations. With this information we simulated populations using a randomly selected 3000 SNPs and a subset of individuals. From this simulation we finally determined that six individuals is the minimum sample size required for the accurate estimation of intra- and inter-population genetic diversity within and across H. axyridis populations. Our findings provide an empirical advantage for population genomic studies of H. axyridis in particular and suggest useful tactics for similar studies on multicellular organisms in general.

Minimum sample sizes for invasion genomics: Empirical investigation in an invasive whitefly

Analysis of population genetics provides insights into the evolutionary processes, among which the sample size choice is per se a crucial issue in the analysis. Genome-wide high-throughput techniques based on RADseq have been increasingly used in studies on the population genomics of invasive species. However, there is little information available regarding optimal sample sizes for analyzing population genomics of invasive species. In this study, we first use type IIB endonucleases restriction site-associated DNA (2b-RAD) to mine thousands of single nucleotide polymorphisms (SNPs) for native and introduced populations in Q1 clade (SPB and 17JN) and Q2 clade (ISQ and UAS0601) of the whitefly, Bemisia tabaci (Gennadius) MED (also known as B. tabaci biotype Q). Then, we used resampling techniques to create simulated populations with a random subset of individuals and 3,000 SNPs to determine how many individuals should be sampled for accurate estimates of intra- and interpopulation genetic diversity. We calculated the intrapopulation genetic diversity parameters (unbiased expected heterozygosity, observed heterozygosity, and the number of effect alleles) and pairwise genetic differentiation F ST; finally, an ad hoc statistic, ΔK, was used to determine the optimal value. Our results showed that a sample size greater than four individuals (n ≥ 4) has little impact on estimates of genetic diversity within whitefly populations; moreover, precise estimate of F ST can be easily achieved at a very small simple size (n = 3 or 4). Our results will provide in-depth understanding of the optimization of sampling schemes in population genomics of invasive species.

Novel H5N6 avian influenza virus reassortants with European H5N8 isolated in migratory birds, China

Five novel H5N6 influenza viruses, including four highly pathogenic avian influenza viruses and one low pathogenic avian influenza virus, were isolated from migratory birds in Ningxia, China, in November 2017. To understand the genetic origination of the novel H5N6 virus, and the infectivity and pathogenicity of the four highly pathogenic avian influenza viruses in mammals, phylogeographic analyses and infection studies in mice were performed. The phylogenetic and phylogeographic analyses showed that the H5N6 isolates, which are closely related to the viruses from Korea, Japan and the Netherlands, originated from reassortant virus between H5N8 and HxN6 viruses from western Russia. The animal study revealed that the SBD-87 isolate presented moderate virulence in mice, suggesting a potential public risk to humans and a potential threat to public health.

Cloning and Functional Analysis of Two Ca2+-Binding Proteins (CaBPs) in Response to Cyantraniliprole Exposure in Bemisia tabaci (Hemiptera: Aleyrodidae)

Ca²⁺-binding proteins (CaBPs) are widely distributed as Ca²⁺ sensor relay proteins that regulate various cellular processes, including Ca²⁺ homeostasis. Diamide insecticides such as cyantraniliprole kill insects by disrupting the Ca²⁺ homeostasis in muscle cells. However, less attention has been paid to the roles of CaBPs in response to insecticides. In this study, two CaBP genes (BtCaBP1 and BtCaBP2) were identified in the whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), and their functions in response to cyantraniliprole were investigated. After expression of BtCaBP1 and BtCaBP2 in vitro, the results of Ca²⁺ imaging and cytotoxicity assay revealed that the overexpression of each of the BtCaBPs stabilized Ca²⁺ concentration in the cytoplasm after exposure to cyantraniliprole and decreased the toxicity of cyantraniliprole against Sf9 cells. However, the knockdown of BtCaBP1 or BtCaBP2 in vivo significantly increased the toxicity of cyantraniliprole to B. tabaci. Taken together, these results provide evidence that BtCaBP1 and BtCaBP2 play a role in response to cyantraniliprole exposure through stabilization of Ca²⁺ concentration in whiteflies.

Prevalence and Genotyping of Toxoplasma gondii Infection in Raccoon Dogs (Nyctereutes procyonoides) in Northern China

Toxoplasma gondii is one of protozoan parasites resulting in zoonosis, which can infect nearly all of warm-blooded hosts, including humans and raccoon dogs (Nyctereutes procyonoides). However, related reports on prevalence and genetic characterization of T. gondii strains in raccoon dogs were few in China. The aim of this study was to survey the prevalence and genetic characterization of T. gondii strains in domestic raccoon dogs from Jilin, Liaoning, and Hebei provinces, northern China. During April 2016 to November 2017, a total of 337 tissue samples collected from domestic raccoon dogs were detected with B1 gene using a nested PCR. And the positive samples were genotyped at 11 genetic markers (SAG1, 5'-and 3'-SAG2, alternative SAG2, SAG3, BTUB, GRA6, L358, PK1, c22-8, c29-2, and Apico) using multilocus PCR-restriction fragment length polymorphism technology. Sixteen out of 337 sika deer (4.75%) were positive with B1 gene by nest PCR. Furthermore, four positive DNA samples were completely typed through further being genotyped, in which three samples were identified as ToxoDB Genotype #9, and one sample was confirmed as ToxoDB Genotype #10. The results of molecular detection not only revealed the existence of T. gondii in domestic raccoon dogs in Jilin, Liaoning, and Hebei for the first time, but also provided the information of genetic diversity. This study also indicated that ToxoDB Genotype #9 as a kind of potential reservoir for T. gondii transmission, may be main genotype in domestic raccoon dogs in China, posing a risk of infection in human health.

Transcriptome Profiling of the Whitefly Bemisia tabaci MED in Response to Single Infection of Tomato yellow leaf curl virus, Tomato chlorosis virus, and Their Co-infection

Tomato yellow leaf curl virus (TYLCV) and Tomato chlorosis virus (ToCV) are two of the most devastating cultivated tomato viruses, causing significant crop losses worldwide. As the vector of both TYLCV and ToCV, the whitefly Bemisia tabaci Mediterranean (MED) is mainly responsible for the rapid spread and mixed infection of TYLCV and ToCV in China. However, little is known concerning B. tabaci MED's molecular response to TYLCV and ToCV infection or their co-infection. We determined the transcriptional responses of the whitefly MED to TYLCV infection, ToCV infection, and TYLCV&ToCV co-infection using Illumina sequencing. In all, 78, 221, and 60 differentially expressed genes (DEGs) were identified in TYLCV-infected, ToCV-infected, and TYLCV&ToCV co-infected whiteflies, respectively, compared with non-viruliferous whiteflies. Differentially regulated genes were sorted according to their roles in detoxification, stress response, immune response, transport, primary metabolism, cell function, and total fitness in whiteflies after feeding on virus-infected tomato plants. Alterations in the transcription profiles of genes involved in transport and energy metabolism occurred between TYLCV&ToCV co-infection and single infection with TYLCV or ToCV; this may be associated with the adaptation of the insect vector upon co-infection of the two viruses. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses demonstrated that the single infection with TYLCV or ToCV and the TYLCV&ToCV co-infection could perturb metabolic processes and metabolic pathways. Taken together, our results provide basis for further exploration of the molecular mechanisms of the response to TYLCV, ToCV single infection, and TYLCV&ToCV co-infection in B. tabaci MED, which will add to our knowledge of the interactions between plant viruses and insect vectors.

Abstract P5-04-06: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Katzenellenbogen JA, Min J, Kim SH, Laws MJ, Zhao Y, Ziegler Y, Nelson ER, Shahoei SH, Chu D, Park BH, Katzenellenbogen BS. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-04-06.

Abstract P2-01-09: ESR1 mutations drive breast cancer metastasis by context-dependent alterations in adhesive and migratory properties

Background: Estrogen receptor alpha (ERα/ESR1) is mutated in 30-40% of endocrine resistant ER+ breast cancer. These mutations, primarily located in the ligand binding domain, are associated with worse outcome in patients, and preclinical studies have shown that they cause ligand independent growth. An open question is whether these mutations contribute to actual metastatic process, or merely endocrine resistance.

Methods: Using Y537S and D538G genome-edited MCF7 and T47D cells, 3D growth was assessed in ultralow attachment plates. Cell-cell adhesion was determined using calcein-labelled adhesion assay and quantitative microfluidic fluorescence microscope (qMFM). Collagen-based adhesion and spheroid invasion assays were used to test adhesive and invasive properties. Wound scratching, spheroid collective migration and Boyden chamber transwell assays were applied to monitor cell migratory phenotypes. Mutated ER cistromes were profiled using ChIP-sequencing. ESR1 mutations in clinical samples were characterized using ddPCR.

Results: Visual inspection of cells grown in suspension culture revealed more compressed multicellular spheroids in ESR1 mutant cells, indicative of increased cell-cell interactions. This observation was confirmed in both static and microfluidic conditions. This effect was more pronounced in MCF7 than T47D cells, correlating with increased expression of desmosome and gap junction genes. Pharmacological blockade of gap junctions decreased cell-cell adhesion. Decreased attachment and increased invasion to collagen were discerned in all mutant cell types. Further functional analysis identified alterations in the TIMP3-MMP axis causing these phenotypes. The cell-cell adhesion phenotypes were restricted to MCF7-Y537S/D538G and T47D-Y537S, whereas T47D-D538G cells showed significantly increased migration. A GSEA screen identified Wnt signaling as uniquely induced in this context, and combination treatment using the Wnt inhibitor LGK974 and Fulvestrant led to synergistic inhibition of migration. ChIP-seq identified mutation-specific cistromes with an overall increased ligand-independent ER binding. However, it did not reveal binding sites in any candidate metastases genes, suggesting secondary epigenetic mechanisms. The motif analysis revealed the enrichment of FOXA1 motifs in mutated ER cistromes except T47D-D538G cells. However, knockdown of FOXA1 induced significantly higher inhibition of T47D-D538G migration than Fulvestrant treatment alone, indicating a FOXA1-dominated mechanism. Collectively, these data show that ESR1 mutant cells gain metastatic properties, in addition to endocrine resistance. To prove this using clinical samples, we measured ESR1 mutations in a well-defined cohort of endocrine resistant local or distant recurrence. Significant enrichment of ESR1 mutations in distant (9/55) vs local (0/27) recurrences confirms critical role of mutant ERα in metastases.

Conclusion: Further analysis of context dependent changes in cell-cell adhesion and migration of ESR1 mutant cells might guide the design and development of drugs targeting ERα-mutant tumors, such as inhibitors of gap junction, FOXA1, MMP, and Wnt signaling pathways.

Disclosure: The authors declare no conflict of interest.

Citation Format: Li Z, Bahreini A, Levine KM, Wang P, Tasdemir N, Montanez MA, Sundd P, Wallace CT, Watkins SC, Chu D, Park BH, Hou W, Mooring MS, Zhu L, Tseng GC, Carroll JS, Atkinson JM, Lee AV, Oesterreich S. ESR1 mutations drive breast cancer metastasis by context-dependent alterations in adhesive and migratory properties [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-01-09.