Sex-Linked Pheromone Receptor Genes of the European Corn Borer, Ostrinia nubilalis, Are in Tandem Arrays

BACKGROUND: Tuning of the olfactory system of male moths to conspecific female sex pheromones is crucial for correct species recognition; however, little is known about the genetic changes that drive speciation in this system. Moths of the genus Ostrinia are good models to elucidate this question, since significant differences in pheromone blends are observed within and among species. Odorant receptors (ORs) play a critical role in recognition of female sex pheromones; eight types of OR genes expressed in male antennae were previously reported in Ostrinia moths. METHODOLOGY/PRINCIPAL FINDINGS: We screened an O. nubilalis bacterial artificial chromosome (BAC) library by PCR, and constructed three contigs from isolated clones containing the reported OR genes. Fluorescence in situ hybridization (FISH) analysis using these clones as probes demonstrated that the largest contig, which contained eight OR genes, was located on the Z chromosome; two others harboring two and one OR genes were found on two autosomes. Sequence determination of BAC clones revealed the Z-linked OR genes were closely related and tandemly arrayed; moreover, four of them shared 181-bp direct repeats spanning exon 7 and intron 7. CONCLUSIONS/SIGNIFICANCE: This is the first report of tandemly arrayed sex pheromone receptor genes in Lepidoptera. The localization of an OR gene cluster on the Z chromosome agrees with previous findings for a Z-linked locus responsible for O. nubilalis male behavioral response to sex pheromone. The 181-bp direct repeats might enhance gene duplications by unequal crossovers. An autosomal locus responsible for male response to sex pheromone in Heliothis virescens and H. subflexa was recently reported to contain at least four OR genes. Taken together, these findings support the hypothesis that generation of additional copies of OR genes can increase the potential for male moths to acquire altered specificity for pheromone components, and accordingly, facilitate differentiation of sex pheromones

Dramatic Transcriptional Changes in an Intracellular Parasite Enable Host Switching between Plant and Insect

Phytoplasmas are bacterial plant pathogens that have devastating effects on the yields of crops and plants worldwide. They are intracellular parasites of both plants and insects, and are spread among plants by insects. How phytoplasmas can adapt to two diverse environments is of considerable interest; however, the mechanisms enabling the “host switching” between plant and insect hosts are poorly understood. Here, we report that phytoplasmas dramatically alter their gene expression in response to “host switching” between plant and insect. We performed a detailed characterization of the dramatic change that occurs in the gene expression profile of Candidatus Phytoplasma asteris OY-M strain (approximately 33% of the genes change) upon host switching between plant and insect. The phytoplasma may use transporters, secreted proteins, and metabolic enzymes in a host-specific manner. As phytoplasmas reside within the host cell, the proteins secreted from phytoplasmas are thought to play crucial roles in the interplay between phytoplasmas and host cells. Our microarray analysis revealed that the expression of the gene encoding the secreted protein PAM486 was highly upregulated in the plant host, which is also observed by immunohistochemical analysis, suggesting that this protein functions mainly when the phytoplasma grows in the plant host. Additionally, phytoplasma growth in planta was partially suppressed by an inhibitor of the MscL osmotic channel that is highly expressed in the plant host, suggesting that the osmotic channel might play an important role in survival in the plant host. These results also suggest that the elucidation of “host switching” mechanism may contribute to the development of novel pest controls

A male-specific odorant receptor conserved through the evolution of sex pheromones in Ostrinia moth species

<p>In many moths, mate-finding communication is mediated by the female sex pheromones. Since differentiation of sex pheromones is often associated with speciation, it is intriguing to know how the changes in female sex pheromone have been tracked by the pheromone recognition system of the males. A male-specific odorant receptor was found to have been conserved through the evolution of sex pheromone communication systems in the genus <i>Ostrinia</i> (Lepidoptera: Crambidae). In an effort to characterize pheromone receptors of <i>O. scapulalis</i>, which uses a mixture of (<i>E</i>)-11- and (<i>Z</i>)-11-tetradecenyl acetates as a sex pheromone, we cloned a gene (<i>OscaOR1</i>) encoding a male-specific odorant receptor. In addition, we cloned a gene of the <i>Or83b</i> family (<i>OscaOR2</i>). Functional assays using <i>Xenopus</i> oocytes co-expressing OscaOR1 and OscaOR2 have shown that OscaOR1 is, unexpectedly, a receptor of (<i>E</i>)-11-tetradecenol (E11-14:OH), a single pheromone component of a congener <i>O. latipennis</i>. Subsequent studies on <i>O. latipennis</i> showed that this species indeed has a gene orthologous to <i>OscaOR1</i> (<i>OlatOR1</i>), a functional assay of which confirmed it to be a gene encoding the receptor of E11-14:OH. Furthermore, investigations of six other <i>Ostrinia</i> species have revealed that all of them have a gene orthologous to <i>OscaOR1</i>, although none of these species, except <i>O. ovalipennis</i>, a species most closely related to <i>O. latipennis</i>, uses E11-14:OH as the pheromone component. The present findings suggest that the male-specific receptor of E11-14:OH was acquired before the divergence of the genus <i>Ostrinia</i>, and functionally retained through the evolution of this genus.</p

RIOK2 Contributes to Cell Growth and Protein Synthesis in Human Oral Squamous Cell Carcinoma

Ribosomes are responsible for the protein synthesis that maintains cellular homeostasis and is required for the rapid cellular division of cancer cells. However, the role of ribosome biogenesis mediators in the malignant behavior of tongue squamous cell carcinoma (TSCC) is unknown. In this study, we found that the expression of RIOK2, a key enzyme involved in the maturation steps of the pre-40S ribosomal complex, was significantly associated with poorer overall survival in patients with TSCC. Further, multivariate analysis revealed that RIOK2 is an independent prognostic factor (hazard ratio, 3.53; 95% confidence interval, 1.19–10.91). Inhibition of RIOK2 expression by siRNA decreased cell growth and S6 ribosomal protein expression in oral squamous cell carcinoma cell lines. RIOK2 knockdown also led to a significant decrease in the protein synthesis in cancer cells. RIOK2 has potential application as a novel therapeutic target for TSCC treatment

Location of the Bombyx mori Aminopeptidase N Type 1 Binding Site on Bacillus thuringiensis Cry1Aa Toxin

We analyzed the binding site on Cry1Aa toxin for the Cry1Aa receptor in Bombyx mori, 115-kDa aminopeptidase N type 1 (BmAPN1) (K. Nakanishi, K. Yaoi, Y. Nagino, H. Hara, M. Kitami, S. Atsumi, N. Miura, and R. Sato, FEBS Lett. 519:215-220, 2002), by using monoclonal antibodies (MAbs) that block binding between the binding site and the receptor. First, we produced a series of MAbs against Cry1Aa and obtained two MAbs, MAbs 2C2 and 1B10, that were capable of blocking the binding between Cry1Aa and BmAPN1 (blocking MAbs). The epitope of the Fab fragments of MAb 2C2 overlapped the BmAPN1 binding site, whereas the epitope of the Fab fragments of MAb 1B10 did not overlap but was located close to the binding site. Using three approaches for epitope mapping, we identified two candidate epitopes for the blocking MAbs on Cry1Aa. We constructed two Cry1Aa toxin mutants by substituting a cysteine on the toxin surface at each of the two candidate epitopes, and the small blocking molecule N-(9-acridinyl)maleimide (NAM) was introduced at each cysteine substitution to determine the true epitope. The Cry1Aa mutant with NAM bound to Cys582 did not bind either of the two blocking MAbs, suggesting that the true epitope for each of the blocking MAbs was located at the site containing Val582, which also consisted of (508)STLRVN(513) and (582)VFTLSAHV(589). These results indicated that the BmAPN1 binding site overlapped part of the region blocked by MAb 2C2 that was close to but excluded the actual epitope of MAb 2C2 on domain III of Cry1Aa toxin. We also discuss another area on Cry1Aa toxin as a new candidate site for BmAPN1 binding

Lectin-Mediated Resistance Impairs Plant Virus Infection at the Cellular Level[C][W][OA]

This work identifies jacalin-type lectin that is responsible for resistance to multiple plant viruses belonging to the genus Potexvirus. The isolation and characterization of this lectin sheds light on a novel resistance machinery to plant viruses

Therapeutic Efficacy and Safety of Lenvatinib after Atezolizumab Plus Bevacizumab for Unresectable Hepatocellular Carcinoma

A total of 137 HCC patients treated with atezolizumab plus bevacizumab from October 2020 to September 2022 were enrolled. The median overall survival (OS) and progression-free survival (PFS) from the beginning of atezolizumab plus bevacizumab were 21.1 months (range, 18.8 months–not reached) and 10.5 months (range, 8.2–12.1 months), respectively. Fifty patients were diagnosed with progressive disease after atezolizumab plus bevacizumab. Of this group, 24 patients were administered lenvatinib, and the median OS and PFS from the beginning of lenvatinib were 15.3 months (range, 10.5 months–not reached) and 4.0 months (range, 2.5–6.4 months), respectively. The objective response rates based on the response evaluation criteria in solid tumors (RECISTs) criteria version 1.1 and modified RECISTs were 33.3% and 54.2%, respectively. There was no significant difference in the median serum alpha-fetoprotein level between before and after lenvatinib. In the multivariate analysis, Child–Pugh class A (hazard ratio 0.02, 95% confidence interval (CI) 0.02–0.76, p = 0.02) and intrahepatic tumor occupancy rate p < 0.01) were the significant factors for OS. There were some frequent adverse events (AEs) in patients treated with lenvatinib such as hypertension, fatigue, anorexia, proteinuria, and so on, but none directly caused death. In conclusion, lenvatinib after atezolizumab plus bevacizumab for unresectable HCC should be considered an effective treatment option