Opsin1 regulates light-evoked avoidance behavior in Aedes albopictus.

BACKGROUND: Mosquitoes locate a human host by integrating various sensory cues including odor, thermo, and vision. However, their innate light preference and its genetic basis that may predict the spatial distribution of mosquitoes, a prerequisite to encounter a potential host and initiate host-seeking behaviors, remains elusive. RESULTS: Here, we first studied mosquito visual features and surprisingly uncovered that both diurnal (Aedes aegypti and Aedes albopictus) and nocturnal (Culex quinquefasciatus) mosquitoes significantly avoided stronger light when given choices. With consistent results from multiple assays, we found that such negative phototaxis maintained throughout development to adult stages. Notably, female mosquitoes significantly preferred to bite hosts in a shaded versus illuminated area. Furthermore, silencing Opsin1, a G protein-coupled receptor that is most enriched in compound eyes, abolished light-evoked avoidance behavior of Aedes albopictus and attenuated photonegative behavior in Aedes aegypti. Finally, we found that field-collected Aedes albopictus also prefers darker area in an Opsin1-dependent manner. CONCLUSIONS: This study reveals that mosquitoes consistently prefer darker environment and identifies the first example of a visual molecule that modulates mosquito photobehavior.

Identification of mucins and their expression in the vector mosquito Aedes albopictus.

Mucins, the main structural components of vertebrate respiratory, digestive and reproductive tract mucus, as well as insect peritrophic matrix, play important roles in protecting host cells from invading microbes and difficult external environments. Mucins are characterized by highly glycosylated proteins constituting the mucin domain that is rich in repetitive sequences of threonine, serine, and proline (PTS). Despite potential important roles, mosquito mucins remain largely uncharacterized. Here, we performed bioinformatics analyses to identify proteins with PTS repeat domain and predicted 43 mucins or mucin-related proteins in Aedes albopictus. Gene expression analysis revealed that these mucins are dynamically expressed across different development stages and in different organs of Aedes albopictus. Of note, blood feeding upregulated AALF016448 and AALF013291 expression in the midgut, fat body, and ovary, raising the possibility that these mucins play potential roles in reproduction, digestion, and intestinal defense against invading pathogens upon blood feeding. Our in silico identification, followed by expressional validation, thus established a valuable resource for further dissecting the functions of mucins for vector control.

A Bacterial Oral Feeding Assay with Antibiotic-Treated Mosquitoes.

The mosquito midgut harbors a highly dynamic microbiome that affects the host metabolism, reproduction, fitness, and vector competence. Studies have been conducted to investigate the effect of gut microbes as a whole; however, different microbes could exert distinct effects toward the host. This article provides the methodology to study the effect of each specific mosquito gut microbe and the potential mechanism. This protocol contains two parts. The first part introduces how to dissect the mosquito midgut, isolate cultivable bacteria colonies, and identify bacteria species. The second part provides the procedure to generate antibiotic-treated mosquitoes and reintroduce one specific bacteria species.

Identification of RT-PCR-Negative Asymptomatic COVID-19 Patients via Serological Testing.

Asymptomatic individuals with coronavirus disease (COVID-19) have been identified via nucleic acid testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); however, the epidemiologic characteristics and viral shedding pattern of asymptomatic patients remain largely unknown. In this study, serological testing was applied when identifying nine asymptomatic cases of COVID-19 who showed persistent negative RT-PCR test results for SARS-CoV-2 nucleic acid and no symptoms of COVID-19. Two asymptomatic cases were presumed to be index patients who had cleared the virus when their close contacts developed symptoms of COVID-19. Three of the asymptomatic cases were local individuals who spontaneously recovered before their presumed index patients developed symptoms of COVID-19. This report presents the epidemiologic and clinical characteristics of asymptomatic individuals with SARS-CoV-2 infection that were undetected on RT-PCR tests in previous epidemiologic investigations probably due to the transient viral shedding duration.

A mosquito salivary protein promotes flavivirus transmission by activation of autophagy.

Transmission from an infected mosquito to a host is an essential process in the life cycle of mosquito-borne flaviviruses. Numerous studies have demonstrated that mosquito saliva facilitates viral transmission. Here we find that a saliva-specific protein, named Aedes aegypti venom allergen-1 (AaVA-1), promotes dengue and Zika virus transmission by activating autophagy in host immune cells of the monocyte lineage. The AG6 mice (ifnar1-/-ifngr1-/-) bitten by the virus-infected AaVA-1-deficient mosquitoes present a lower viremia and prolonged survival. AaVA-1 intracellularly interacts with a dominant negative binder of Beclin-1, known as leucine-rich pentatricopeptide repeat-containing protein (LRPPRC), and releases Beclin-1 from LRPPRC-mediated sequestration, thereby enabling the initialization of downstream autophagic signaling. A deficiency in Beclin-1 reduces viral infection in mice and abolishes AaVA-1-mediated enhancement of ZIKV transmission by mosquitoes. Our study provides a mechanistic insight into saliva-aided viral transmission and could offer a potential prophylactic target for reducing flavivirus transmission.

Host serum iron modulates dengue virus acquisition by mosquitoes.

A blood meal is the primary route through which mosquitoes acquire an arbovirus infection. Blood components or their metabolites may regulate the susceptibility of mosquitoes to arboviruses. Here we report that serum iron in human blood influences dengue virus acquisition by mosquitoes. Dengue virus acquisition by Aedes aegypti was inversely correlated with the iron concentration in serum from human donors. In a mouse-mosquito acquisition model, iron supplementation reduced dengue virus prevalence and viral load, whereas neutralization of serum iron facilitated dengue virus infection in A. aegypti mosquitoes. Of note, mosquitoes feeding on iron-deficient (sideropenic) mice exhibited a higher prevalence of dengue virus. Reversal of the sideropenic status of hosts largely reduced dengue virus acquisition and infection by mosquitoes. Serum iron, rather than haem-bound iron, was utilized by the mosquito iron metabolism pathway to boost the activity of reactive oxygen species in the gut epithelium, subsequently inhibiting infection by dengue virus. On the basis of these results, a status of iron deficiency in the human population might contribute to the vectorial permissiveness to dengue virus, thereby facilitating its spread by mosquitoes.

Arbovirus lifecycle in mosquito: acquisition, propagation and transmission.

Mosquitoes are haematophagous vectors for hundreds of pathogenic viruses that are aetiological agents of human diseases. In nature, mosquito-borne viruses maintain a lifecycle between mosquitoes and vertebrate animals. Viruses are acquired by a naive mosquito from an infected host by blood meals and then propagate extensively in the mosquito's tissues. This mosquito then becomes a virus reservoir and is competent to transmit the viruses to a naive vertebrate host through the next blood meal. To survive in and efficiently cycle between two distinct host environments, mosquito-borne viruses have evolved delicate and smart strategies to comprehensively exploit host and vector factors. Here, we provide an update on recent studies of the mechanisms of virus survival in, acquisition and transmission by mosquitoes.

A Gut Commensal Bacterium Promotes Mosquito Permissiveness to Arboviruses.

Mosquitoes are hematophagous vectors that can acquire human viruses in their intestinal tract. Here, we define a mosquito gut commensal bacterium that promotes permissiveness to arboviruses. Antibiotic depletion of gut bacteria impaired arboviral infection of a lab-adapted Aedes aegypti mosquito strain. Reconstitution of individual cultivable gut bacteria in antibiotic-treated mosquitoes identified Serratia marcescens as a commensal bacterium critical for efficient arboviral acquisition. S. marcescens facilitates arboviral infection through a secreted protein named SmEnhancin, which digests membrane-bound mucins on the mosquito gut epithelia, thereby enhancing viral dissemination. Field Aedes mosquitoes positive for S. marcescens were more permissive to dengue virus infection than those free of S. marcescens. Oral introduction of S. marcescens into field mosquitoes that lack this bacterium rendered these mosquitoes highly susceptible to arboviruses. This study defines a commensal-driven mechanism that contributes to vector competence, and extends our understanding of multipartite interactions among hosts, the gut microbiome, and viruses.

Integrin-linked kinase is overexpressed in laryngeal squamous cell carcinoma and correlates with tumor proliferation, migration and invasion.

OBJECTIVE: To investigate the role of integrin-linked kinase (ILK) in invasion and metastasis of the laryngeal squamous cell carcinomas (LSCC) and to evaluate the effects of antisense oligonucleotide sequence (ASONs) targeting the ILK gene on the proliferation, epithelial-mesenchymal transition (EMT), migration and invasion of LSCC. PATIENTS AND METHODS: 116 patients who had previously undergone complete resection of the tumor for LSCC were studied retrospectively. The ILK expression level in tumor tissues and adjacent normal tissues were determined by immunohistochemistry. The changes of ILK expression from each group were assessed and correlated to the clinical parameters of the patients. Secondly, ILK antisense oligonucleotide (ILK-ASONS) was used to silence the ILK gene of LSCC cell from Hep-2 cell line. The expression of ILK, epithelial marker E-cadherin and mesenchymal marker Vimentin were evaluated by Western blotting. The proliferation of cells after transfection was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). The apoptosis was detected by flow cytometry. The migration and invasion activity of Hep-2 cells was detected by Matrigel invasion and cell migration assays. RESULTS: The expression of the ILK protein was significantly associated with tumor differentiation (p=0.046), lymph node metastasis (p=0.020) and pTNM stage (p=0.019). ILK ASONS-transfected cells showed a significant decrease in cell proliferation, cell migration and invasive activity compared to mock-transfected cells. ILK ASONS-transfected cells increased the expression of E-cadherin, whereas the expression of ILK and Vimentin decreased, compared with mock-transfected cells. CONCLUSIONS: The expression of ILK was significantly correlated with differentiation and metastasis of the laryngeal carcinomas. The inhibition of the ILK gene could downregulate the proliferation, migration and invasion of Hep-2 cells. These findings suggest that the ILK gene could be a potential target for the treatment of laryngeal cancer.

The p38 MAPK-regulated PKD1/CREB/Bcl-2 pathway contributes to selenite-induced colorectal cancer cell apoptosis in vitro and in vivo.

Supranutritional selenite has anti-cancer therapeutic effects in vivo; however, the detailed mechanisms underlying these effects are not clearly understood. Further studies would broaden our understanding of the anti-cancer effects of this compound and provide a theoretical basis for its clinical application. In this study, we primarily found that selenite exposure inhibited phosphorylation of cyclic adenosine monophosphate (cAMP)-response element binding protein (CREB), leading to suppression of Bcl-2 in HCT116 and SW480 colorectal cancer (CRC) cells. Moreover, the selenite-induced inhibitory effect on PKD1 activation was involved in suppression of the CREB signalling pathway. Additionally, we discovered that selenite treatment can upregulate p38 MAPK phosphorylation, which results in inhibition of the PKD1/CREB/Bcl-2 survival pathway and triggers apoptosis. Finally, we established a colorectal cancer xenograft model and found that selenite treatment markedly inhibits tumour growth through the MAPK/PKD1/CREB/Bcl-2 pathway in vivo. Our results demonstrated that a supranutritional dose of selenite induced CRC cell apoptosis through inhibition of the PKD1/CREB/Bcl-2 axis both in vitro and in vivo.

ATF4 activation by the p38MAPK-eIF4E axis mediates apoptosis and autophagy induced by selenite in Jurkat cells.

Previous studies have shown that selenite exerts pro-apoptosis and pro-autophagy effects and is associated with the activation of ER stress in T-cell acute lymphoblastic leukemia (T-ALL). Herein we demonstrate the underlying mechanisms by which the activation of p38MAPK plays essential roles in apoptosis and autophagy and the coordination of cellular metabolic processes during leukemia therapy. MKK3/6-dependent activation of p38MAPK is required for the phosphorylation of eIF4E, thus initiating the translation of ER stress-related transcription factor ATF4. Upregulated ATF4 results in the transcriptional initiation of the apoptosis-related chop gene and autophagy-related map1lc3b gene, through which selenite links ER stress to apoptosis and autophagy during leukemia treatment. Moreover, autophagy induction enhances cell apoptosis under this condition.

Prospective study of sensorineural hearing loss following radiotherapy for nasopharyngeal carcinoma.

OBJECTIVES: To investigate the severity and incidence of sensorineural hearing loss in patients with nasopharyngeal carcinoma treated with radiotherapy. METHODS: Forty-two patients with nasopharyngeal carcinoma were treated with conventional radiotherapy. Audiological testing was performed to compare patients' hearing before and at varying stages after radiotherapy. RESULTS: At one month post-radiation, a significant hearing threshold increase was seen only for high frequencies. At 12, 24 and 60 months post-radiation, significant threshold increases were observed at speech frequencies (4.0 and 8.0 kHz), compared with pre-radiation data. The mean values of wave I, III and V latencies and of the I-V interpeak latency intervals were not significantly altered at one month post-radiation, but were significantly prolonged at 12, 24 and 60 months post-radiation, compared with pre-radiation data. CONCLUSION: In patients with nasopharyngeal carcinoma treated with radiotherapy, the severity and incidence of radiation-induced sensorineural hearing loss increased with time, especially at high frequencies. This hearing impairment may be due to changes in the cochlea and/or the retrocochlear auditory pathway.

Osteoclast-like giant cell carcinoma of the urinary bladder.

Extraskeletal osteoclast-like giant cell (OGC) tumors are uncommon and have mainly been found in the breast and pancreas. OGC neoplasms of the urinary tract are extremely rare, and their histogenesis and biologic behavior remain controversial. Gross hematuria is the most common presenting symptom, as in transitional cell carcinoma. The prognosis is poor in patients with extraskeletal OGC tumors. Here, we present the case of a 62-year-old man who received transurethral bladder tumor resection due to painless gross hematuria. Pathology showed OGC carcinoma. Abdominal computed tomography showed tumor invasion over the right lateral wall of the bladder and distal third of the ureter. The patient received radical cystectomy and partial distal ureterectomy with transureteroureterostomy. No local tumor recurrence or distant metastasis was found at the 5-month follow-up.