Noise correction in differential phase contrast for improving phase sensitivity.

Differential phase contrast (DPC) imaging relies on computational analysis to extract quantitative phase information from phase gradient images. However, even modest noise level can introduce errors that propagate through the computational process, degrading the quality of the final phase result and further reducing phase sensitivity. Here, we introduce the noise-corrected DPC (ncDPC) to enhance phase sensitivity. This approach is based on a theoretical DPC model that effectively considers most relevant noise sources in the camera and non-uniform illumination in DPC. In particular, the dominating shot noise and readout noise variance can be jointly estimated using frequency analysis and further corrected by block-matching 3D (BM3D) method. Finally, the denoised images are used for phase retrieval based on the common Tikhonov inversion. Our results, based on both simulated and experimental data, demonstrate that ncDPC outperforms the traditional DPC (tDPC), enabling significant improvements in both phase reconstruction quality and phase sensitivity. Besides, we have demonstrated the broad applicability of ncDPC by showing its performance in various experimental datasets.

Conserved microRNAs miR-8-3p and miR-2a-3 targeting chitin biosynthesis to regulate the molting process of Sogatella furcifera (Horváth)(Hemiptera: Delphacidae).

Molting is a key solution to growth restriction in insects. The periodic synthesis and degradation of chitin, one of the major components of the insect epidermis, is necessary for insect growth. MicroRNA (miRNA) have been implicated in molting regulation, yet their involvement in the interplay interaction between the chitin synthesis pathway and 20-hydroxyecdysone signaling remains poorly understood. In this study, soluble trehalase (Tre1) and phosphoacetylglucosamine mutase (PAGM) were identified as targets of conserved miR-8-3p and miR-2a-3, respectively. The expression profiles of miR-8-3p-SfTre1 and miR-2a-3-SfPAGM exhibited an opposite pattern during the different developmental stages, indicating a negative regulatory relationship between them. This relationship was confirmed by an in vitro dual-luciferase reporter system. Overexpression of miR-8-3p and miR-2a-3 by injection of mimics inhibited the expression of their respective target genes and increased mortality, leading to death in the pre-molting, and molting death phenomena. They also caused a decrease in chitin content and expression levels of key genes in the chitin synthesis pathway (SfTre1, SfTre2, SfHK, SfG6PI, SfGFAT, SfGNA, SfPAGM, SfUAP, SfCHS1, SfCHS1a, and SfCHS1b). Conversely, the injection of miRNA inhibitors resulted in the upregulation of the expression levels of these genes. Following 20E treatment, the expression levels of miR-8-3p and miR-2a-3 decreased significantly, while their corresponding target genes increased significantly. These results indicate that miR-8-3p and miR-2a-3 play a regulatory role in the molting of Sogatella furcifera by targeting SfTre1 and SfPAGM, respectively. These findings provide new potential targets for the development of subsequent new control strategies.

Wing expansion functional analysis of ion transport peptide gene in Sogatella furcifera (Horváth) (Hemiptera: Delphacidae).

Ion transport peptide (ITP), a superfamily of arthropod neuropeptides, serves a crucial role in regulating various physiological processes such as diuresis, ecdysis behavior, and wing expansion. However, the molecular characteristics, expression profile, and role of ITP in Sogatella furcifera are poorly understood. To elucidate the characteristics and biological function of ITP in S. furcifera, we employed reverse transcription-polymerase chain reaction (RT-PCR) and RNA interference (RNAi) methods. The identified SfITP gene encodes 117 amino acids. The expression of SfITP gradually increased followed the formation of 3-day-old of 5th instar nymph, peaking initially at 40 min after eclosion, and reaching another peak 24 h after eclosion, with particularly high expression levels in thorax and wing tissues. Notably, SfITP RNAi in 3rd instar nymphs of S. furcifera significantly inhibited the transcript levels of SfITP, resulting in 55% mortality and 78% wing deformity. These findings suggests that SfITP is involved in the regulation of wing expansion in S. furcifera, providing insights into the regulation of insect wing expansion and contributing to the molecular understanding of this process.

Buprofezin affects the molting process by regulating nuclear receptors SfHR3 and SfHR4 in Sogatella furcifera.

Nuclear receptors play a crucial role in various signaling and metabolic pathways, such as insect molting and development. Buprofezin (2-tert-butylimino-3-isopropyl-5-phenyl-perhydro-1, 3, 5-thiadiazin-4-one), a chitin synthesis inhibitor, causes molting deformities and slow death in insects by inhibiting chitin synthesis and interfering with their metabolism. This study investigated whether buprofezin affects insect ecdysteroid signaling pathway. The treatment of buprofezin significantly suppressed the transcription levels of SfHR3 and SfHR4, two nuclear receptor genes, in third-instar nymphs of Sogatella furcifera. Meanwhile, the transcription levels of SfHR3 and SfHR4 in first-day fifth-instar nymphs were induced at 12 h after 20E treatment. In addition, the silencing of SfHR3 and SfHR4 genes in first-day fifth-instar nymphs caused severe developmental delay and molting failure, resulting in a significant reduction of survival rates at 7.36% and 2.99% on the eighth day, respectively. Further analysis showed that the silencing SfHR3 and SfHR4 significantly inhibited the transcription levels of chitin synthesis and degradation-related genes. These results indicate that buprofezin can inhibits chitin synthesis and degradation by suppressing the signal transduction of 20E through SfHR3 and SfHR4, leading to molting failure and death. This study not only expands our understanding of the molecular mechanism of buprofezin in pest control but also lays a foundation for developing new control strategies of RNAi by targeting SfHR3 and SfHR4.

Interaction Analysis of lncRNA and mRNA Based on the Full-Length Transcriptome of the Nymph-to-Adult Developmental Transition of Sogatella furcifera.

Little is known on how long noncoding RNAs (lncRNAs) and mRNAs cooperatively participate in regulating the nymph-to-adult development transition of Sogatella furcifera. Herein, lncRNA and mRNA libraries were constructed in three different developmental stages of S. furcifera, namely, prior to (PE), during (DE), and after (AE) ecdysis. Overall, 4649 lncRNAs were identified and divided into intergenic (53.90%), intronic (1.33%), sense (8.99%), antisense (21.75%), and bidirectional (3.94%) lncRNAs. Moreover, 795 differentially expressed lncRNAs were identified. Specifically, upon comparing PE and DE, 2719 target mRNAs were predicted for 574 lncRNAs. Upon comparing PE and AE, 2816 target mRNAs were predicted for 627 lncRNAs. Finally, upon comparing DE and AE, 51 target mRNAs were predicted for 35 lncRNAs. Kyoto Encyclopedia of Genes and Genome functional enrichment analysis revealed that the target genes of 795 lncRNAs were enriched in metabolic pathways, amino sugar and nucleotide sugar metabolism, and fatty acid metabolism. Subsequently, interaction analysis indicated that MSTRG.16086.1, MSTRG.16087.1, and MSTRG.2447.1 were functionally associated with cuticle protein and chitin biosynthesis. Finally, 11 differentially expressed lncRNAs were significantly enriched in 3rd and 4th instar nymphs. Our findings suggest that lncRNAs play a critical regulatory role during the molting of S. furcifera.

SfDicer1 participates in the regulation of molting development and reproduction in the white-backed planthopper, Sogatella furcifera.

Dicer1 plays a vital role in the formation of mature miRNA and regulates the growth, development, and reproduction of insects. However, it remains to be clarified whether Dicer1 is involved in regulating the biological processes underlying molting and reproduction of Sogatella furcifera (Horváth). Herein, SfDicer1 expression fluctuated in all the developmental stages of S. furcifera and increased as molting progressed. SfDicer1 exhibited high expression in the integument, head, fat body, and ovary of the insects. SfDicer1 dsRNA injection into 1-day-old fourth instar nymphs of S. furcifera substantially decreased the survival rate and expression of the lethal phenotypes of wing malformation and molting defects and significantly inhibited the expression of four conserved miRNAs associated with molting development. Subsequently, following the knockdown of SfDicer1 in the newly emerged (1-12 h) females of S. furcifera, SfVg and SfVgR expression levels were decreased, thereby delaying ovarian development, decreasing the number of eggs, and considerably reducing the hatching rate compared with those of the control. Finally, after silencing SfDicer1 for 48 h, the comparative transcriptome analysis of differentially expressed genes revealed considerable enrichment of the Gene Ontology terms structural constituent of cuticle, structural molecule activity, chitin metabolic process, amino sugar metabolic process, and intracellular anatomical structure, indicating that SfDicer1 inhibition affects the transcription of genes associated with growth and development. Thus, our results suggest that SfDicer1 is essential in the molting, survival, ovarian development, and fecundity of S. furcifera and is a suitable target gene for developing an RNAi-based strategy targeting the most destructive rice insect pest.

Knockdown of Two Trehalase Genes by RNA Interference Is Lethal to the White-Backed Planthopper Sogatella furcifera (Horváth) (Hemiptera: Delphacidae).

Trehalase (Tre) is a crucial enzyme involved in trehalose metabolism, and it plays pivotal roles in insect development and metamorphosis. However, the biological function of Tre genes in Sogatella furcifera remains unclear. In the present study, two Tre genes-SfTre1 and SfTre2-were cloned and identified based on the S. furcifera transcriptome data. Bioinformatic analysis revealed that the full-length complementary DNA of SfTre1 and SfTre2 genes were 3700 and 2757 bp long, with 1728- and 1902-bp open reading frame encoding 575 and 633 amino acid residues, respectively. Expression analysis indicated that SfTre1 and SfTre2 were expressed at all developmental stages, with the highest expression in day two adults. Furthermore, the highest expression levels of SfTre1 and SfTre2 were observed in the ovary; enriched expression was also noted in head tissues. The knockdown of SfTre1 and SfTre2 via injecting double-stranded RNAs decreased the transcription levels of the corresponding mRNAs and led to various malformed phenotypes and high lethality rates. The results of our present study indicate that SfTre1 and SfTre2 play crucial roles in S. furcifera growth and development, which can provide referable information for Tre genes as a potential target for planthopper control.

SfDicer2 RNA Interference Inhibits Molting and Wing Expansion in Sogatella furcifera.

Endoribonuclease 2 (Dicer2) is a key nicking endonuclease involved in the small interfering RNA biosynthesis, and it plays important roles in gene regulation and antiviral immunity. The Dicer2 sequence was obtained using the transcriptomic and genomic information of Sogatella furcifera (Horváth), and the spatiotemporal characteristics and functions of molting and wing expansion regulation were studied using real-time quantitative polymerase chain reaction and RNA interference (RNAi) technology. The expression of SfDicer2 fluctuated during the nymphal stage of S. furcifera. Its expression decreased significantly over the course of molting. SfDicer2 exhibited the highest transcript level in the nymphal stage and adult fat body. After SfDicer2 was silenced, the total mortality rate was 42.69%; 18.32% of the insects died because of their inability to molt. Compared with the effects of dsGFP or water, 44.38% of the insects subjected to the silencing of SfDicer2 exhibited wing deformities after successful eclosion. After SfDicer2 RNAi, the expression of chitinase, chitin deacetylase, trehalase, chitin synthase 1, and wing expansion-related genes was significantly inhibited. These findings indicate that SfDicer2 controls molting by affecting genes associated with chitin synthesis and degradation and regulates wing expansion by altering the expression of wing expansion-related genes in S. furcifera.

Identification and profiling of Sogatella furcifera microRNAs and their potential roles in regulating the developmental transitions of nymph-adult.

Sogatella furcifera is one of the most serious insect pests that affect rice in Asia. One class of small RNAs (sRNAs; ~22 nt long) is miRNAs, which participate in various biological processes by regulating the expression of target genes in a spatiotemporal manner. However, the role of miRNAs in nymph-to-adult transition in S. furcifera remains unknown. In this study, we sequenced sRNA libraries of S. furcifera prepared from individuals at three different developmental stages (pre-moult, moulting and early adult). A total of 253 miRNAs (134 known and 119 novel) were identified, of which 12 were differentially expressed during the nymph-to-adult developmental transition. Moreover, Real time quantitative PCR (RT-qPCR) analysis revealed that all 12 miRNAs were differentially expressed among five different nymph tissues and 14 different developmental stages (first to fifth instar nymphs and 1-day-old adults). Injection of miR-2a-2 mimic/antagomir and miR-305-5p-1 mimic/antagomir into 1-day-old fifth instar nymphs significantly increased the mortality rate. In addition, a defective moulting phenotype was observed in nymphs injected with miR-2a-2 and miR-305-5p-1, suggesting that these miRNAs are involved in S. furcifera nymph-adult transition. In conclusion, these results reveal the function of critical miRNAs in S. furcifera nymph-adult transition, and also provide novel potential targets of insecticides for the long-term sustainable management of S. furcifera.

Evaluation of Biological Effects and Transcriptome Changes Induced by LED-Based Narrow-Band UVB Phototherapy.

Ultraviolet (UV), particularly UVB, is widely used in the treatment of skin diseases including psoriasis, atopic dermatitis, vitiligo, mycosis fungoides and pruritus. Recently, there has been a trend of replacing broad-band UVB (BB-UVB) units with narrow-band UVB (NB-UVB), as studies have demonstrated that NB-UVB is more efficacious in the treatment of psoriasis. The purpose of this study is to evaluate the biological effects and transcriptome changes induced by light-emitting diode-based NB-UVB (NB-UVB LED) phototherapy. Cell viability and the cell migration ability were significantly decreased posttreatment, as well as apoptosis and ROS levels were remarkably increased. NB-UVB-induced S phase arrest was observed 12 h postirradiation. Bioinformatics analysis of transcriptome sequencing data revealed that NB-UVB LED irradiation induced dose-depended changes in multiple key signaling pathways, such as PI3K and cytoskeletal-related pathways. The depolymerization of cytoskeleton induced by NB-UVB was observed 24 h posttreatment. In addition, the expression levels of cytoskeleton-related proteins FN1, ITGB4, ITGA1, RAC2 and DOCK1 decreased significantly 12 h after irradiation. Our results indicated that NB-UVB LED may serve as a novel option for the development of NB-UVB phototherapy devices.

Silencing of Decapentaplegic (Dpp) gene inhibited the wing expansion in the white-backed planthopper, Sogatella furcifera (Horváth) (Hemiptera: Delphacidae).

The Decapentaplegic gene controls wing patterning and spreading by regulating downstream genes in many insect species. However, the molecular characteristics, expression, and biological function of Dpp in Sogatella furcifera remain poorly understood. In this study, we cloned the Dpp gene from S. furcifera and examined its expression levels in different development stages, wing typed adults, and tissues. Then, the function of SfDpp gene was analyzed using an RNA interference (RNAi)-based approach. The results showed that the full-length complementary DNA  of the SfDpp gene consists of 1034 bp and contains a 954-bp open reading frame encoding 317 amino acids. SfDpp has a transforming growth factor-ß (TGF-ß) propeptide superfamily domain and a TGF-ß superfamily domain, typical of members of the TGF-ß superfamily. Quantitative real-time polymerase chain reaction showed that the expression of SfDpp reached its highest expression level 40 min after eclosion. RNAi-based gene silencing inhibited transcript levels of the corresponding messenger RNA in S. furcifera nymphs injected with double-stranded RNA of SfDpp and resulted in death of 29.17% and 26.67% of 4th and 5th instar nymphs, respectively. The wing deformity rate of the adults was 74.12% and 3.41% after SfDpp gene silencing in 4th and 5th instar nymphs, respectively. Examining wing development-associated genes showed that two target genes of Dpp (Vestigial and Spalt) were both dramatically downregulated after SfDpp was silenced. Our results demonstrate that downregulated SfDpp in early development causes wing expansion failure in S. furcifera. Thus, Dpp may be a target gene for restricting the migration of rice-damaging planthoppers.

Juvenile Hormone Synthesis Pathway Gene SfIPPI Regulates Sogatella furcifera Reproduction.

The juvenile hormone (JH) is crucial for insect reproduction, and isopentenyl pyrophosphate isomerase (IPPI) is a key enzyme in the JH synthesis pathway. However, few studies have investigated how IPPI regulates insect reproduction. This study identifies and characterizes the IPPI gene (SfIPPI) from the important agricultural pest Sogatella furcifera. A phylogenetic analysis reveals a high homology of SfIPPI with the IPPI amino acid sequences of Laodelphax striatellus and Nilaparvata lugens (Stål). Furthermore, SfIPPI is expressed at various developmental stages and in various tissues of S. furcifera, and is significantly higher on the 5th day of adult emergence and in integument tissue, while lower levels are found on the 3rd day of adult emergence and in fat body and gut tissue. After silencing SfIPPI using RNA interference, the ovarian development is significantly inhibited and the fecundity is significantly reduced when compared with the control group. Additionally, SfIPPI silencing significantly decreases the expression levels of downstream JH signal transduction pathway genes (SfJHAMT, SfFAMeT, and SfKr-h1) and SfVg. Our findings are helpful in elucidating the molecular mechanism underlying the regulation of insect reproduction through genes in the JH synthesis pathway, and they provide a theoretical basis for the development of pest control treatments targeting SfIPPI.

Identification and RNAi-Based Functional Analysis of Four Chitin Deacetylase Genes in Sogatella furcifera (Hemiptera: Delphacidae).

Chitin deacetylases (CDAs) are chitin-degrading enzymes that play a key role in insect molting. In this study, we identified and characterized four full-length cDNAs of CDAs from Sogatella furcifera (Horváth). Developmental expression showed that SfCDA1 and SfCDA2 were expressed at all nymph developmental stages, SfCDA3 and SfCDA4 were mainly expressed in the third-instar to fifth-instar nymph stages, whereas tissue-specific analyses indicated that four CDA genes were mainly high expressed in the integument and head during the fifth-instar nymph. RNA interference (RNAi) results revealed that SfCDA1, SfCDA2, and SfCDA4 are associated with molting defect and high mortality with nymph-adult molting. Furthermore, transcripts of chitin synthase 1 variants (SfCHS1, SfCHS1a, and SfCHS1b) were significantly downregulated and causing significant changes in the expression levels of trehalases (TRE1 and TRE2) in the SfCDA1, SfCDA2, and SfCDA4 dsRNA treatment groups. By contrast, no significant phenotypic characteristics were observed after dsSfCDA3 injection. Taken together, our results suggest that SfCDA1, SfCDA2, and SfCDA4 play a vital role in nymph-adult transition, and these genes could regulate chitin biosynthesis expression levels.

Role of SfJHAMT and SfFAMeT in the reproductive regulation of Sogatella furcifera and its expression under insecticide stress.

The isoprene branching pathway is a unique downstream synthesis pathway of juvenile hormone (JH) in arthropods, which plays an important role in the growth, development, and reproduction of insects. Juvenile hormone acid O-methyltransferase (JHAMT) and farnesoic acid O-methyltransferase (FAMeT) are two key proteins that are regulated in the isoprene branching pathway. Based on the available transcriptomic and genomic data of Sogatella furcifera, full-length cDNAs of SfJHAMT and SfFAMeT were identified. In vitro injection of dsRNA targeted to silence SfJHAMT and SfFAMeT inhibited the fecundity, ovarian development, and transcription levels of SfKr-h1 and SfVg significantly. Of note, The transcription levels of SfJHAMT and SfFAMeT are regulated mutually; i.e., silencing of SfJHAMT causes an increase in the SfFAMeT transcription level and vice versa, and the negative effect of simultaneous silencing on reproduction is greater. The results revealed a coordinated effect of SfJHAMT and SfFAMeT on the reproductive capabilities of S. furcifera. Furthermore, a JH analog (methoprene) partially rescued the negative effect of simultaneous silencing by SfJHAMT and SfFAMeT on reproduction. In addition, the expression profile analysis after insecticide stress showed that triazophos (LC25) can induce the transcription of SfMet and SfKr-h1 to promote JH signal transduction, which affects the transcription of SfVg and ultimately promotes the reproduction of S. furcifera. The results of the present study lay a foundation to further explain the isoprene branch pathway function in insect reproduction and can open up new avenues for sustainable pest control while expanding the current understanding of molecular mechanisms through which insecticides stimulate reproduction and lead to pest resurgence.

Characterization and functional analysis of chitinase family genes involved in nymph-adult transition of Sogatella furcifera.

Chitinase degrades chitin in the old epidermis or peritrophic matrix of insects, which ensures normal development and metamorphosis. In our previous work, we comprehensively studied the function of SfCht7 in Sogatella furcifera. However, the number and function of chitinase genes in S. furcifera remain unknown. Here, we identified 12 full-length chitinase transcripts from S. furcifera, which included nine chitinase (Cht), two imaginal disc growth factor (IDGF), and one endo-ß-N-acetylglucosaminidase (ENGase) genes. Expression analysis results revealed that the expression levels of eight genes (SfCht3, SfCht5, SfCht6-1, SfCht6-2, SfCht7, SfCht8, SfCht10, and SfIDGF2) with similar transcript levels peaked prior to molting of each nymph and were highly expressed in the integument. Based on RNA interference (RNAi), description of the functions of each chitinase gene indicated that the silencing of SfCht5, SfCht10, and SfIDGF2 led to molting defects and lethality. RNAi inhibited the expressions of SfCht5, SfCht7, SfCht10, and SfIDGF2, which led to downregulated expressions of chitin synthase 1 (SfCHS1, SfCHS1a, and SfCHS1b) and four chitin deacetylase genes (SfCDA1, SfCDA2, SfCDA3, and SfCDA4), and caused a change in the expression level of two trehalase genes (TRE1 and TRE2). Furthermore, silencing of SfCht7 induced a significant decrease in the expression levels of three wing development-related genes (SfWG, SfDpp, and SfHh). In conclusion, SfCht5, SfCht7, SfCht10, and SfIDGF2 play vital roles in nymph-adult transition and are involved in the regulation of chitin metabolism, and SfCht7 is also involved in wing development; therefore, these genes are potential targets for control of S. furcifera.

Effects of Sublethal Concentrations of Insecticides on the Fecundity of Sogatella furcifera (Hemiptera: Delphacidae) via the Regulation of Vitellogenin and Its Receptor.

White-backed planthopper (Sogatella furcifera, Hemiptera: Delphacidae) is an important migratory pest of rice. It causes severe economic losses by reducing crop production. Vg and VgR are important proteins that help in the successful reproduction of insects and have been studied in many insects. To understand the molecular mechanisms underlying the effects of insecticides on white-backed planthopper reproduction, we studied the expression profiles of SfVg, SfVg-like, and SfVgR in white-backed planthopper exposed to insecticides. SfVg and SfVgR silencing inhibited the ovarian development, number of eggs laid by, and hatching rate of white-backed planthopper. Thiamethoxam LC10 significantly inhibited SfVg-like and SfVgR expression. In contrast, triazophos LC25 significantly promoted SfVg, SfVg-like, and SfVgR expression and increased vitellogenin content in white-backed planthopper. These results demonstrate that insecticides can regulate the reproduction of white-backed planthopper by altering the expression of SfVg and SfVgR, thereby affecting the population density of white-backed planthopper. These findings build a foundation for improving our understanding of the molecular mechanisms underlying the effects of insecticides on the reproduction and resurgence of pests.

Proteome and phosphoproteome profiling reveals the regulation mechanism of hibernation in a freshwater leech (Whitmania pigra).

Hibernation is an energy-saving and adaptive strategy adopted by leech, an important medicinal resource in Asia, to survive low temperature. Reversible protein phosphorylation (RPP) plays a key role in the regulation of mammalian hibernation processes but has never been documented in freshwater invertebrate such as leech. In this study, we detected the effects of hibernation on the proteome and phosphoproteome of the leech Whitmania pigra. A total of 2184 proteins and 2598 sites were quantified. Deep-hibernation resulted in 85 up-regulated and 107 down-regulated proteins and 318 up-regulated and 204 down-regulated phosphosites using a 1.5-fold threshold (P<0.05). Proteins involved in protein digestion and absorption, amino acid metabolism and N-glycan biosynthesis were significantly down-regulated during deep-hibernation. However, proteins involved in maintaining cell structure stability in hibernating animals were up-regulated. Differentially phosphorylated proteins provided the first global picture of a shift in energy metabolism, protein synthesis, cytoprotection and signaling during deep hibernation. Furthermore, AMP-activated protein kinase and protein kinase C play major roles in the regulation of these functional processes. These data significantly improve our understanding of the regulatory mechanisms of leech hibernation processes and provides substantial candidate phosphorylated proteins that could be important for functionally adapt in freshwater animals. SIGNIFICANCE: The leech Whitmania pigra as an important medicinal resource in Asia is an excellent model freshwater invertebrate for studies of environmentally-induced hibernation. The present study provides the first quantitative proteomics and phosphoproteomic analysis of leech hibernation using isobaric tag based TMT labeling and high-resolution mass spectrometry. These data significantly improve our understanding of the regulatory mechanisms when ectotherm animals face environmental stress and provides substantial candidate phosphorylated proteins that could be important for functionally adapt in freshwater animals.

Unibody microscope objective tipped with a microsphere: design, fabrication, and application in subwavelength imaging.

Microsphere-based subwavelength imaging technique was first demonstrated in 2011. After nearly a decade of efforts, such technique has spawned numerous interests in fields such as laser nano-machining, imaging, sensing, and biological detection. For wider industrial-scale application of the technique, a robust and low-cost objective lens incorporating a microsphere lens is highly desired and sought by many researchers. In this work, we demonstrate a unibody microscope objective lens formed by tipping a high-index microsphere onto a plano-convex lens and subsequently fitting them into a conventional objective lens. We call this the plano-convex-microsphere (PCM) objective, which resembles the appearance and operation of an ordinary microscope objective while providing super-resolving power in discerning subwavelength 100 nm features ($\lambda /{4}.{7}$λ/4.7) in air and far-field conditions. The imaging performance of the PCM objective, along with the working distance, has been systematically investigated. It has a calibrated resolution of $\lambda /{3}$λ/3 in the far field, a numerical aperture of 1.57, and a working distance of 3.5 µm. With the assistance of a scanning process, larger-area imaging is realized. The PCM objective can be easily adapted to existing microscope systems and is appealing for commercialization.

Superlensing plano-convex-microsphere (PCM) lens for direct laser nano-marking and beyond.

A high-performance all-dielectric lens, formed by integrating a conventional plano-convex lens with a high-index microsphere lens (PCM), was developed for far-field super-resolution applications. The PCM lens features a theoretical resolution of $\sim\lambda /{2.5}$∼λ/2.5 in air with a WD $\sim 2\;{\unicode{x00B5} \rm m}$∼2µm away from the lens. When combined with a femtosecond laser, the actual patterning resolution can reach $\sim\lambda /{3.5}$∼λ/3.5. The unusual focusing properties were theoretically and experimentally verified, and direct laser nano-writing of arbitrary patterns and nanostructures on various substrates was demonstrated. This Letter can be naturally extended to other super-resolution applications, including imaging, sensing, and trapping, with the potential of developing next-generation low-cost direct laser nano-marking machine and super-resolution imaging nanoscope.

Effects of abiotic stress on the expression of Hsp70 genes in Sogatella furcifera (Horváth).

Sogatella furcifera (Horváth), a prominent rice pest in Asia, is a typical R-strategic and highly adaptable insect. Heat shock proteins (Hsps) are highly conserved molecular chaperones regulating responses to various abiotic stresses; however, limited information is available regarding their role in responding to abiotic stress in S. furcifera. This study aimed to investigate the effect of abiotic stresses on the expression of Hsp70 genes in the S. furcifera. Five Hsp70 genes were isolated from S. furcifera, and the expression patterns at different developmental stages and temperatures, upon treatment with different insecticides and ultraviolet A (UV-A) stress, were analyzed. Hsp70 genes were expressed at different developmental stages. Hsp70-2, Hsp70-5, and Hsp70-6 were significantly upregulated upon heat shock at 40 °C for 30 min. Hsp70-3 and Hsp70-4 were significantly upregulated upon heat shock at 30 °C for 30 min. Under UV-A stress, Hsp70-3, Hsp70-4, Hsp70-5, and Hsp70-6 were significantly upregulated. Conversely, Hsp70-2 was significantly downregulated under UV-A stress. The five Hsp70 genes were significantly downregulated in 3rd-instar nymphs on exposure to thiamethoxam, buprofezin, and avermectin at LC10 and LC25 concentrations. Hence, Hsp70 genes significantly contribute to the tolerance of S. furcifera to temperature and UV-A stress; however, they are not involved in the response to insecticides.