Abstract:This study presents an antibody-conjugated polydiacetylene (PDA) and its coated polyvinylidene difluoride (PVDF) membrane. The M149 antibody was hybridized to nano-vesicles consisting of pentacosa-10,12-diynoic acid (PCDA) and dimyristoylphosphatidylcholine (DMPC). After photo-polymerization at 254 nm, the effects on the PDA by antigenic injection were investigated with UV-vis spectroscopy, fluorescence spectroscopy, dynamic light scattering and transmission electron microscopy. Because PDA, an alternating ene-yne molecule, induces a blue-to-red color transition and an interesting fluorescent response by the distortion of its backbone, the biomolecular recognition of an antibody-antigen can be converted into an optical and fluorescent signal. Thus, an influenza antigen was successfully detected with the proposed label-free method. Furthermore, the vesicular system was improved by coating it onto a membrane type sensing platform for its stability and portability. The proposed antibody-PDA composite PVDF membrane has potential for rapid, easy and selective visualization of the influenza virus.

The rapid detection of foot‐and‐mouth disease virus (FMDV) is vital for the prevention of foot‐and‐mouth disease outbreaks. In this study, a polyvinylidene difluoride (PVDF)‐supported polydiacetylene (PDA) immunosensor is developed to detect FMDV, in which a polyclonal antibody against the FMDV VP1 antigen is conjugated as a specific virus‐binding module without a linker. First, a liposome‐based immunosensor is generated for the FMDV VP1 protein in the form of photopolymerized PDA colloids. Then, the VP1‐specific PDA immunosensors are modified onto PVDF strip to enable the rapid and portable detection of FMDV. Detailed analyses are performed using ultraviolet‐visible spectroscopy, dynamic light scattering, transmission electron microscopy, and scanning electron microscopy. A blue‐to‐red color transition is observed in the presence of FMDV particles, indicating the potential applications of FMDV‐specific PDA immunosensors for use in solid‐phase detection as well as via liquid‐phase liposome platforms. Thus, this work provides a rapid and simple detection for FMDV.

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NSD1 is a histone methyltransferase that methylates the lysine 36 at histone H3. NSD duplication is associated with short stature, microcephaly, intellectual disability, and behavioral defects in humans. Ectopic overexpression of NSD, an NSD1 homolog in Drosophila, was shown to induce developmental abnormalities via apoptosis. In this study, to investigate the effects of NSD overexpression on Drosophila brain development, we first examined the typical NSD expression pattern in larval brains and found that endogenous NSD promoter activity was detected only in subsets of glial cells. Pan-glial, but not panneuronal, NSD overexpression induced apoptosis in larval brain cells. However, pan-glial NSD overexpression also induced caspase-3 cleavage in neuronal cells. Among the various glial cell types, NSD overexpression in only astrocytic glia induced apoptosis and abnormal learning defects in the larval stage. Furthermore, NSD overexpression downregulated the expression of various astrocyte-specific genes, including draper (drpr), possibly owing to an indirect effect of NSD overexpression-induced astrocytic apoptosis. Since drpr plays a role in axon pruning during mushroom body (MB) formation in Drosophila astrocytes, we examined the effect of astrocytic NSD overexpression on this process and found that it disrupted the clearance of γ-neurons in the MB, subsequently inducing arrhythmic locomotor activity of the fly. Thus, these results suggest that aberrant NSD overexpression may cause neurodevelopmental disorders by interfering with crucial functions of astrocytes in the brain, underlining the importance of the tightly controlled astrocytic NSD expression for proper neurodevelopment.

The Drosophila nuclear receptor-binding SET domain protein (NSD) gene encodes the Drosophila ortholog of mammalian NSD family members that are important in many aspects of development and disease in humans. In this study, we observed that overexpression of Drosophila NSD in imaginal discs induces organ atrophy. Thus, to gain an understanding of the transcriptional regulation of the gene, we analyzed the NSD promoter region. First, we identified the presence of three putative DNA replication-related element (DRE) sequences in its promoter region, where DRE-binding factor (DREF) could bind for transcriptional activation. In the experiments with the fly GAL4-UAS system, we demonstrated that overexpressed DREF increased the endogenous NSD transcription. To confirm the role of DREF as a transcriptional activator on the NSD expression, we generated a series of luciferase reporter gene constructs containing deleted portions of the 5'-flanking regions as well as point mutations in the putative DRE sites. When transiently transfected into S2 cells, the deletion construct containing no DRE sites showed dramatic decrease in the NSD promoter activity, but only two sites near the transcriptional start site were important. Furthermore, we verified the direct interaction of DREF with the two positively cis-acting sequences on the NSD promoter by chromatin immunoprecipitation assay. Taken together, these results demonstrated that NSD is one of the downstream targets of the DRE/DREF pathway that is associated with various cellular processes in Drosophila, indicating that our findings may contribute to the understanding of molecular mechanisms in complex disorders associated with NSD family members in humans.