Green Fluorescent Protein Expression Research Articles

Lineage-tracing reveals an expanded population of NPY neurons in the inferior colliculus.

Growing evidence suggests that neuropeptide signaling shapes auditory computations. We previously showed that neuropeptide Y (NPY) is expressed in the inferior colliculus (IC) by a population of GABAergic stellate neurons and that NPY regulates the strength of local excitatory circuits in the IC. NPY neurons were initially characterized using the NPY-hrGFP mouse, in which humanized renilla green fluorescent protein (hrGFP) expression indicates NPY expression at the time of assay, i.e., an expression-tracking approach. However, studies in other brain regions have shown that NPY expression can vary based on several factors, suggesting that the NPY-hrGFP mouse might miss NPY neurons not expressing NPY on the experiment date. Here, we hypothesized that neurons with the ability to express NPY represent a larger population of IC GABAergic neurons than previously reported. To test this hypothesis, we used a lineage-tracing approach to irreversibly tag neurons that expressed NPY at any point prior to the experiment date. We then compared the physiological and anatomical features of neurons labeled with this lineage-tracing approach to our prior data set, revealing a larger population of NPY neurons than previously found. In addition, we used optogenetics to test the local connectivity of NPY neurons and found that NPY neurons provide inhibitory synaptic input to other neurons in the ipsilateral IC. Together, our data expand the definition of NPY neurons in the IC, suggest that NPY expression might be dynamically regulated in the IC, and provide functional evidence that NPY neurons form local inhibitory circuits in the IC.NEW & NOTEWORTHY Across brain regions, neuropeptide Y (NPY) expression is dynamic and influenced by extrinsic and intrinsic factors. We previously showed that NPY is expressed by a class of inhibitory neurons in the auditory midbrain. Here, we find that this neuron class also includes neurons that previously expressed NPY, suggesting that NPY expression is dynamically regulated in the auditory midbrain. We also provide functional evidence that NPY neurons contribute to local inhibitory circuits in the auditory midbrain.

Selaginella tamariscina Ethanol Extract Attenuates Influenza A Virus Infection by Inhibiting Hemagglutinin and Neuraminidase.

Selaginella tamariscina is a perennial plant that is used for diverse diseases. This study investigated whether Selaginella tamariscina has an antiviral effect against influenza A virus (IAV) infection. We used green fluorescent protein (GFP)-tagged influenza A virus (IAV) to examine the effect of Selaginella tamariscina ethanol extract (STE) on influenza viral infection. Fluorescence microscopy and flow cytometry showed that STE potently represses GFP expression by the virus, dose-dependently. STE significantly inhibited the expression of the IAV M2, NP, HA, NA, NS1, and PB2 proteins. Time-of-addition and hemagglutination inhibition assays showed that STE has an inhibitory effect on hemagglutinin and viral binding on the cells at an early infection time. In addition, STE exerted a suppressive effect on the neuraminidase activity of the H1N1 and H3N2 IAVs. Furthermore, dose-dependently, STE inhibited the cytopathic effect induced by H3N2, as well as by H1N1 IAV. Especially in the presence of 200 µg/mL STE, the cytopathic effect was completely blocked. Our findings suggest that STE has antiviral efficacy against IAV infection; thus, it could be developed as a natural IAV inhibitor.

Matrix attachment regions enhance transgene expression by manipulating position-dependent effects in stably transfected CHO-K1 cells.

We previously found that the position of matrix attachment regions (MARs) within the vector significantly affects its ability to enhance transgenic expression in the recombinant protein production. This study aims to systematically investigate the position-dependent impacts of MAR on transgene expression. We observed a significant increase in enhanced green fluorescent protein (eGFP) expression levels in stably transfected CHO-K1 cells with either MAR 1-68 or MAR X-29 when MARs located upstream of the promoter. This increase was especially evident with MAR flanked the expression cassette. Concurrently, a substantial increase was observed in the percentage of eGFP-expressing cells, with 97.8% and 96.0% in MAR-containing constructs versus 73.7% in MAR-absent constructs. Further analysis of erythropoietin (EPO) expression revealed that constructs with flanking MARs induced the highest EPO productivity. Bioinformatics analysis revealed that certain specific transcription factors are important in modulating the transcription process. In conclusion, vectors harboring both MARs around the expression cassette constitute an optimal construct for enhanced recombinant protein production in CHO-K1 cells. This insight underscores the importance of strategic MAR incorporation in vector design for optimized recombinant protein expression.

β-glycerophosphate, not low magnitude fluid shear stress, increases osteocytogenesis in the osteoblast-to-osteocyte cell line IDG-SW3

ABSTRACT Aim As osteoblasts deposit a mineralized collagen network, a subpopulation of these cells differentiates into osteocytes. Biochemical and mechanical stimuli, particularly fluid shear stress (FSS), are thought to regulate this, but their relative influence remains unclear. Here, we assess both biochemical and mechanical stimuli on long-term bone formation and osteocytogenesis using the osteoblast-osteocyte cell line IDG-SW3. Methods Due to the relative novelty and uncommon culture conditions of IDG-SW3 versus other osteoblast-lineage cell lines, effects of temperature and media formulation on matrix deposition and osteocytogenesis were initially characterized. Subsequently, the relative influence of biochemical (β-glycerophosphate (βGP) and ascorbic acid 2-phosphate (AA2P)) and mechanical stimulation on osteocytogenesis was compared, with intermittent application of low magnitude FSS generated by see-saw rocker. Results βGP and AA2P supplementation were required for mineralization and osteocytogenesis, with 33°C cultures retaining a more osteoblastic phenotype and 37°C cultures undergoing significantly higher osteocytogenesis. βGP concentration positively correlated with calcium deposition, whilst AA2P stimulated alkaline phosphatase (ALP) activity and collagen deposition. We demonstrate that increasing βGP concentration also significantly enhances osteocytogenesis as quantified by the expression of green fluorescent protein linked to Dmp1. Intermittent FSS (~0.06 Pa) rocker had no effect on osteocytogenesis and matrix deposition. Conclusions This work demonstrates the suitability and ease with which IDG-SW3 can be utilized in osteocytogenesis studies. IDG-SW3 mineralization was only mediated through biochemical stimuli with no detectable effect of low magnitude FSS. Osteocytogenesis of IDG-SW3 primarily occurred in mineralized areas, further demonstrating the role mineralization of the bone extracellular matrix has in osteocyte differentiation.

Mapping the chromatin accessibility landscape of zebrafish embryogenesis at single-cell resolution by SPATAC-seq.

Currently, the dynamic accessible elements that determine regulatory programs responsible for the unique identity and function of each cell type during zebrafish embryogenesis lack detailed study. Here we present SPATAC-seq: a split-pool ligation-based assay for transposase-accessible chromatin using sequencing. Using SPATAC-seq, we profiled chromatin accessibility in more than 800,000 individual nuclei across 20 developmental stages spanning the sphere stage to the early larval protruding mouth stage. Using this chromatin accessibility map, we identified 604 cell states and inferred their developmental relationships. We also identified 959,040 candidate cis-regulatory elements (cCREs) and delineated development-specific cCREs, as well as transcription factors defining diverse cell identities. Importantly, enhancer reporter assays confirmed that the majority of tested cCREs exhibited robust enhanced green fluorescent protein expression in restricted cell types or tissues. Finally, we explored gene regulatory programs that drive pigment and notochord cell differentiation. Our work provides a valuable open resource for exploring driver regulators of cell fate decisions in zebrafish embryogenesis.

Comparative Approaches for Quantification of Product Yield in a Model Recombinant Green Fluorescent Protein Expressed in E. coli.

Process Analytical Technologies (PAT) used to monitor and control manufacturing processes are crucial for efficient and automated bioprocessing, which is in congruence with lights-off-manufacturing and Industry 4.0 initiatives. As biomanufacturing seeks to realize more high-throughput and automated operation, an increasing need for multimodal analysis of process metrics becomes essential. Herein, we detail a series of methods for analyzing product yield from a bioreactor and how to conduct cross-method comparisons. We employ a model system of Escherichia coli (E. coli) expression of green fluorescent protein (GFP), which is a simple, cost effective model for students and educators to replicate at different scales. GFP is an ideal analytical marker as it is easy to visualize due to its fluorescence which indicates cellular protein expression, cell localization and physiological changes of the cell population. In this study, samples from a 300 L bioreactor with GFP-expressing E. coli are analyzed to improve product yield and bioprocessing efficiency. Utilizing a fed-batch process for enhanced cell density and product titer, this bioreactor runs on a 24-hour schedule from inoculation to GFP induction and final harvest. To reliably quantify relative GFP expression and E. coli proliferation, we provide simple protocols and example results for comparing three different analytical methods: (1) in-line bioreactor measurements, (2) plate reader assays, and (3) microscopy. The GFP and cell density results follow similar trends based on the various inline and offline analytical methods and show a peak of GFP expression and cell density between 12.5 and 18 hours post inoculation.

Knock out aryl hydrocarbon receptor gene in adipose-derived mesenchymal stem cell line (PT-5006) by CRISPR/Cas9

Mesenchymal stem cells (MSCs) have garnered significant attention in biomedical studies due to their remarkable properties, such as self-renewal, differentiation into diverse cell types and immune responses. The proliferation and differentiation of MSCs are significantly influenced by the ligand-dependent transcription factor known as the aryl hydrocarbon receptor (AhR). In order to understand the roles of Ahr in adipose-derived MSCs (AD-MSCs), we disrupted the Ahr gene in this work using CRISPR/Cas9 gene editing technology. The gRNA/Cas9 dual vector and donor vector were introduced into the AD-MSC cell line (PT-5006). Green fluorescent protein (GFP) expression and puromycin resistance were used to identify the transfected cells. AhR-KO cells were cloned and confirmed by PCR and sequencing. By using RT-qPCR, the expression levels of AhR and the Ahr-related gene Cyp1B1 were investigated. The results showed that the knocked out of AhR using CRISPR/Cas9, resulting significantly decreased expression of 7.69-fold for AhR and 3.70-fold for Cyp1B1 in the cells. These cell clones and CRISPR/Cas9 vectors could be used as tools to investigate the functions of AhR in both AD-MSCs and other cell types.

DNA Delivery by Virus-Like Nanocarriers in Plant Cells.

Tobacco mild green mosaic virus (TMGMV)-like nanocarriers were designed for gene delivery to plant cells. High aspect ratio TMGMVs were coated with a polycationic biopolymer, poly(allylamine) hydrochloride (PAH), to generate highly charged nanomaterials (TMGMV-PAH; 56.20 ± 4.7 mV) that efficiently load (1:6 TMGMV:DNA mass ratio) and deliver single-stranded and plasmid DNA to plant cells. The TMGMV-PAH were taken up through energy-independent mechanisms in Arabidopsis protoplasts. TMGMV-PAH delivered a plasmid DNA encoding a green fluorescent protein (GFP) to the protoplast nucleus (70% viability), as evidenced by GFP expression using confocal microscopy and Western blot analysis. TMGMV-PAH were inactivated (iTMGMV-PAH) using UV cross-linking to prevent systemic infection in intact plants. Inactivated iTMGMV-PAH-mediated pDNA delivery and gene expression of GFP in vivo was determined using confocal microscopy and RT-qPCR. Virus-like nanocarrier-mediated gene delivery can act as a facile and biocompatible tool for advancing genetic engineering in plants.

β-Cyclocitral from Lavandula angustifolia Mill. Exerts Anti-Aging Effects on Yeasts and Mammalian Cells via Telomere Protection, Antioxidative Stress, and Autophagy Activation.

We used a replicative lifespan (RLS) experiment of K6001 yeast to screen for anti-aging compounds within lavender extract (Lavandula angustifolia Mill.), leading to the discovery of β-cyclocitral (CYC) as a potential anti-aging compound. Concurrently, the chronological lifespan (CLS) of YOM36 yeast and mammalian cells confirmed the anti-aging effect of CYC. This molecule extended the yeast lifespan and inhibited etoposide (ETO)-induced cell senescence. To understand the mechanism of CYC, we analyzed its effects on telomeres, oxidative stress, and autophagy. CYC administration resulted in notable increases in the telomerase content, telomere length, and the expression of the telomeric shelterin protein components telomeric-repeat binding factor 2 (TRF2) and repressor activator protein 1 (RAP1). More interestingly, CYC reversed H2O2-induced telomere damage and exhibited strong antioxidant capacity. Moreover, CYC improved the survival rate of BY4741 yeast under oxidative stress induced by 6.2 mM H2O2, increasing the antioxidant enzyme activity while reducing the reactive oxygen species (ROS), reactive nitrogen species (RNS), and malondialdehyde (MDA) levels. Additionally, CYC enhanced autophagic flux and free green fluorescent protein (GFP) expression in the YOM38-GFP-ATG8 yeast strain. However, CYC did not extend the RLS of K6001 yeast mutants, such as Δsod1, Δsod2, Δcat, Δgpx, Δatg2, and Δatg32, which lack antioxidant enzymes or autophagy-related genes. These findings reveal that CYC acts as an anti-aging agent by modifying telomeres, oxidative stress, and autophagy. It is a promising compound with potential anti-aging effects and warrants further study.

SMAD4 promotes somatic-germline contact during murine oocyte growth.

Development of the mammalian oocyte requires physical contact with the surrounding granulosa cells of the follicle, which provide it with essential nutrients and regulatory signals. This contact is achieved through specialized filopodia, termed transzonal projections (TZPs), that extend from the granulosa cells to the oocyte surface. Transforming growth factor (TGFβ) family ligands produced by the oocyte increase the number of TZPs, but how they do so is unknown. Using an inducible Cre recombinase strategy together with expression of green fluorescent protein to verify Cre activity in individual cells, we examined the effect of depleting the canonical TGFβ mediator, SMAD4, in mouse granulosa cells. We observed a 20-50% decrease in the total number of TZPs in SMAD4-depleted granulosa cell-oocyte complexes, and a 50% decrease in the number of newly generated TZPs when the granulosa cells were reaggregated with wild-type oocytes. Three-dimensional image analysis revealed that TZPs of SMAD4-depleted cells were longer than controls and more frequently oriented towards the oocyte. Strikingly, the transmembrane proteins, N-cadherin and Notch2, were reduced by 50% in SMAD4-depleted cells. SMAD4 may thus modulate a network of cell adhesion proteins that stabilize the attachment of TZPs to the oocyte, thereby amplifying signalling between the two cell types.

Tissue Tension and Strain as Indicators of Suction‐mediated Cutaneous DNA Transfection: A Parametric Study

AbstractCutaneous suction‐based transfection is a recently developed technique that is painless and simple‐to‐use for the delivery of DNA for nucleic‐acid‐based vaccines. The technique promises high efficiency for both antigen expression and immunogenicity as demonstrated in both animal studies and human clinical trials. To realize this promise, a parametric study and systematic evaluation of the efficacy of cutaneous suction as a transfection method is performed. Using Green Fluorescent Protein (GFP) plasmid expression as a transfection reporter in a rat model, the expression level as a function of both suction nozzle size and suction pressure is quantified. A numerical model is employed to compute skin deformation in terms of strain, which is used to correlate with GFP expression. Based on these results, two quantities, integrated total strain and tissue tension, are proposed as indicators of expression level that can be used to guide protocol development and optimization. These indicators are also discussed in relation to possible cellular uptake mechanisms.

Biolistics-mediated transformation of hornworts and its application to study pyrenoid protein localization.

Hornworts are a deeply diverged lineage of bryophytes and a sister lineage to mosses and liverworts. Hornworts have an array of unique features that can be leveraged to illuminate not only the early evolution of land plants, but also alternative paths for nitrogen and carbon assimilation via cyanobacterial symbiosis and a pyrenoid-based CO2-concentrating mechanism (CCM), respectively. Despite this, hornworts are one of the few plant lineages with limited available genetic tools. Here we report an efficient biolistics method for generating transient expression and stable transgenic lines in the model hornwort, Anthoceros agrestis. An average of 569 (±268) cells showed transient expression per bombardment, with green fluorescent protein expression observed within 48-72 h. A total of 81 stably transformed lines were recovered across three separate experiments, averaging six lines per bombardment. We followed the same method to transiently transform nine additional hornwort species, and obtained stable transformants from one. This method was further used to verify the localization of Rubisco and Rubisco activase in pyrenoids, which are central proteins for CCM function. Together, our biolistics approach offers key advantages over existing methods as it enables rapid transient expression and can be applied to widely diverse hornwort species.

Gene Transfection Efficiency Improvement with Lipid Conjugated Cationic Carbon Dots.

An ideal vehicle with a high transfection efficiency is crucial for gene delivery. In this study, a type of cationic carbon dot (CCD) known as APCDs were first prepared with arginine (Arg) and pentaethylenehexamine (PEHA) as precursors and conjugated with oleic acid (OA) for gene delivery. By tuning the mass ratio of APCDs to OA, APCDs-OA conjugates, namely, APCDs-0.5OA, APCDs-1.0OA, and APCDs-1.5OA were synthesized. All three amphiphilic APCDs-OA conjugates show high affinity to DNA through electrostatic interactions. APCDs-0.5OA exhibit strong binding with small interfering RNA (siRNA). After being internalized by Human Embryonic Kidney (HEK 293) and osteosarcoma (U2OS) cells, they could distribute in both the cytoplasm and the nucleus. With APCDs-OA conjugates as gene delivery vehicles, plasmid DNA (pDNA) that encodes the gene for the green fluorescence protein (GFP) can be successfully delivered in both HEK 293 and U2OS cells. The GFP expression levels mediated by APCDs-0.5OA and APCDs-1.0OA are ten times greater than that of PEI in HEK 293 cells. Furthermore, APCDs-0.5OA show prominent siRNA transfection efficiency, which is proven by the significantly downregulated expression of FANCA and FANCD2 proteins upon delivery of FANCA siRNA and FANCD2 siRNA into U2OS cells. In conclusion, our work demonstrates that conjugation of CCDs with a lipid structure such as OA significantly improves the gene transfection efficiency, providing a new idea about the designation of nonviral carriers in gene delivery systems.

Establishment of an Efficient Protoplast Isolation and Transfection Method for Eucommia ulmoides Oliver.

Eucommia ulmoides Oliver is a unique high-quality natural rubber tree species and rare medicinal tree species in China. The rapid characterization of E. ulmoides gene function has been severely hampered by the limitations of genetic transformation methods and breeding cycles. The polyethylene glycol (PEG)-mediated protoplast transformation system is a multifunctional and rapid tool for the analysis of functional genes in vivo, but it has not been established in E. ulmoides. In this study, a large number of highly active protoplasts were isolated from the stems of E. ulmoides seedlings by enzymatic digestion, and green fluorescent protein expression was facilitated using a PEG-mediated method. Optimal enzymatic digestion occurred when the enzyme was digested for 10 h in an enzymatic solution containing 2.5% Cellulase R-10 (w/v), 0.6% Macerozyme R-10 (w/v), 2.5% pectinase (w/v), 0.5% hemicellulase (w/v), and 0.6 mol/L mannitol. The active protoplast yield under this condition was 1.13 × 106 protoplasts/g fresh weight, and the protoplast activity was as high as 94.84%. This study established the first protoplasm isolation and transient transformation system in hard rubber wood, which lays the foundation for subsequent functional studies of E. ulmoides genes to achieve high-throughput analysis, and provides a reference for future gene function studies of medicinal and woody plants.

Preparation of Chitosan Nanoparticles through a Readily Solvent-Exchange Process for Efficient and Enhanced Gene Delivery.

In view of the excellent prospects of gene therapy and the potential safety and immunogenicity issues challenged by viral vectors, it is of great significance to develop a nonviral vector with low toxicity and low cost. In this work, we report a chitosan nanoparticle (CSNP) to be used as a gene vector prepared through a facile solvent-exchange strategy. Chitosan is first dissolved in ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIM Ac), and then, the solvent is exchanged with water/phosphate-buffered saline (PBS) to remove ionic liquid, forming a final CSNP dispersion after ultrasonication. The prepared CSNP shows a positive surface charge and can condense green fluorescent protein-encoding plasmid (pGFP) at weight ratios (CSNP/pGFP) of 5/1 or higher. Dynamic light scattering size and ζ-potential characterization and gel retardation results confirm the formation of CSNP/pGFP complexes. Compared with plain pGFP, efficient cellular internalization and significantly enhanced green fluorescent protein (GFP) expression are observed by using CSNP as a plasmid vector. Benefitting from the intrinsic biocompatibility, low cost, low immunogenicity, and abundant sources of chitosan, as well as the facile preparation and the efficient gene transfection capacity of CSNP, it is believed that this CSNP could be used as a nonviral gene vector with great clinical translational potentials.

Investigating the Role of Arcuate Pirt Neurons in Energy Homeostasis

The arcuate nucleus (ARC) is a critical hypothalamic region for the control of metabolism and feeding. Previous studies show that a subgroup of inhibitory ARC neurons, which express the vesicular inhibitory amino acid transporter gene ( Slc32a1) and the leptin receptor gene ( Lepr), control metabolism but not feeding. However, the identity of these neurons remains elusive. We identified a candidate neuron subtype in the ARC, marked by the expression of the phosphoinositide interacting regulator of the transient receptor potential ( Pirt) gene. We hypothesize, based on their molecular profile, that PirtARC neurons are activated by feeding to drive thermogenesis. We used the Pirt-Cre transgenic mouse to investigate the role of PirtARC neurons in energy homeostasis. To validate Cre activity, we expressed a reporter virus (AAV8-hSyn-FLEX-TVA-P2A-GFP-2A-oG) in the ARC of male and female Pirt-Cre mice (n=4; 6 injections, 50 nL each) and compared GFP (green fluorescent protein) fluorescence to Pirt expression by RNA fluorescence in situ hybridization (RNA FISH). In the absence of Cre expression, we failed to detect GFP expression, confirming the Cre dependency of the AAV. However, in Pirt-Cre mice, we found that 77% (380 of 495) of ARC Pirt RNA+neurons were GFP+ and that 79% (380 of 483) of GFP+ ARC neurons were Pirt RNA+, thereby validating the Pirt-Cre mouse for genetically targeting PirtARC neurons. Next, to investigate whether PirtARC neurons respond to metabolic states, we subjected male and female C57BL/6J mice to ad libitum feeding, 18-hour fasting, and 18-hour fasting then 2-hour refeeding (n=4 mice per condition). Using RNA FISH, we assessed the co-localization of Pirt mRNA with Fos mRNA (neuronal activity marker) across the metabolic states. We found that the percentage of PirtARC neurons co-expressing Fos mRNA is higher in ad libitum-fed mice than in fasted mice (p=0.0135; one-way ANOVA followed by Tukey’s multiple comparison test), though neither group differed significantly from post-fast re-fed mice (p > 0.05). This indicates that PirtARC neurons are more active in fed mice than fasted ones, consistent with our hypothesis. Finally, to investigate whether PirtARC neurons regulate food intake, we expressed the intersectional chemogenetics (AAV-CreON/FlpON-hM3Dq-HA) in the ARC of male and female Pirt-Cre::Slc32a1-Flp mice (n=6; 6 injections, 100 nL each) to activate PirtARC neurons. We intraperitoneally injected the artificial muscarinic receptor ligand, clozapine N-oxide (CNO; 1 mg/kg), or saline vehicle in ad libitum-fed mice during the 12-hour light cycle and measured food intake after 30 minutes, 1 hour, 2 hours, and 4 hours on alternating days (CNO, 0.11 ± 0.05 g food/4 hrs.; saline, 0.11 ± 0.04 g food/4 hrs.; Two-way ANOVA, CNO vs saline, p > 0.05 for all time points). Unlike other ARC inhibitory neurons, we found that activating PirtARC neurons does not increase food intake. Together, our results show that PirtARC neurons are a novel subtype of feeding-activated, non-orexigenic neurons in the arcuate hypothalamus. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Transduction and Genome Editing of the Heart with Adeno-Associated Viral Vectors Loaded onto Electrospun Polydioxanone Nonwoven Fabrics.

In this study, we introduce electrospun polydioxanone (PDO) nonwoven fabrics as a platform for the delivery of adeno-associated virus (AAV) vectors for transduction and genome editing by adhering them to organ surfaces, including the heart. AAV vectors were loaded onto the PDO fabrics by soaking the fabrics in a solution containing AAV vectors. In vitro, the amount of AAV vectors loaded onto the fabrics could be adjusted by changing their concentration in the solution, and the number of cells expressing the green fluorescent protein (GFP) encoded by the AAV vectors increased in correlation with the increasing amount of loaded AAV vectors. In vivo, both transduction and genome editing resulted in the observation of GFP expression around AAV vector-loaded PDO fabrics attached to the surfaces of mouse hearts, indicating effective transduction and expression at the target site. These results demonstrate the great potential of electrospun PDO nonwoven fabrics carrying therapeutic AAV vectors for gene therapy.

Motor, somatosensory, and executive cortical areas elicit monosynaptic and polysynaptic neuronal activity in the auditory midbrain

We recently reported that the central nucleus of the inferior colliculus (the auditory midbrain) is innervated by glutamatergic pyramidal cells originating not only in auditory cortex (AC), but also in multiple ‘non-auditory’ regions of the cerebral cortex. Here, in anaesthetised rats, we used optogenetics and electrical stimulation, combined with recording in the inferior colliculus to determine the functional influence of these descending connections. Specifically, we determined the extent of monosynaptic excitation and the influence of these descending connections on spontaneous activity in the inferior colliculus.A retrograde virus encoding both green fluorescent protein (GFP) and channelrhodopsin (ChR2) injected into the central nucleus of the inferior colliculus (ICc) resulted in GFP expression in discrete groups of cells in multiple areas of the cerebral cortex. Light stimulation of AC and primary motor cortex (M1) caused local activation of cortical neurones and increased the firing rate of neurones in ICc indicating a direct excitatory input from AC and M1 to ICc with a restricted distribution. In naïve animals, electrical stimulation at multiple different sites within M1, secondary motor, somatosensory, and prefrontal cortices increased firing rate in ICc. However, it was notable that stimulation at some adjacent sites failed to influence firing at the recording site in ICc. Responses in ICc comprised singular spikes of constant shape and size which occurred with a short, and fixed latency (∼ 5 ms) consistent with monosynaptic excitation of individual ICc units. Increasing the stimulus current decreased the latency of these spikes, suggesting more rapid depolarization of cortical neurones, and increased the number of (usually adjacent) channels on which a monosynaptic spike was seen, suggesting recruitment of increasing numbers of cortical neurons. Electrical stimulation of cortical regions also evoked longer latency, longer duration increases in firing activity, comprising multiple units with spikes occurring with significant temporal jitter, consistent with polysynaptic excitation. Increasing the stimulus current increased the number of spikes in these polysynaptic responses and increased the number of channels on which the responses were observed, although the magnitude of the responses always diminished away from the most activated channels. Together our findings indicate descending connections from motor, somatosensory and executive cortical regions directly activate small numbers of ICc neurones and that this in turn leads to extensive polysynaptic activation of local circuits within the ICc.

Temperature/GSH Dual Responsive Fluorinated Mesoporous Silica‐Coated Au NRs for Serum‐Resistant Gene Delivery**

AbstractMesoporous silica nanoparticles (MSN) are emerging as one of the most appealing candidates for gene carriers. Nevertheless, one major obstacle for their clinical application is the lack of efficient controlled release and gene delivery. In this study, a mesoporous silica‐modified gold nanorods (Au NRs) controlled release platform was synthesized. Then a thermosensitive copolymer was grafted to the surface of release platform, to impart the switching response of carrier under the photothermal of Au NRs. Fluorination were modified on the surface of MSN through a disulfide bond to achieve glutathione (GSH) response release and improve serum‐resistant ability. This gene carrier, with notable DNA condensation ability and negligible cytotoxicity, could be easily internalized into cells, enhanced green fluorescent protein expression in the presence of serum under laser irradiation. This work inspired us to solve the problem of traditional controllable sustained release and realize the performance of intracellular switch response to gene sustained release.

A hybrid RNA-protein biosensor for high-throughput screening of adenosylcobalamin biosynthesis

Genetically encoded circuits have been successfully utilized to assess and characterize target variants with desirable traits from large mutant libraries. Adenosylcobalamin is an essential coenzyme that is required in many intracellular physiological reactions and is widely used in the pharmaceutical and food industries. High-throughput screening techniques capable of detecting adenosylcobalamin productivity and selecting superior adenosylcobalamin biosynthesis strains are critical for the creation of an effective microbial cell factory for the production of adenosylcobalamin at an industrial level. In this study, we developed an RNA-protein hybrid biosensor whose input part was an endogenous RNA riboswitch to specifically respond to adenosylcobalamin, the inverter part was an orthogonal transcriptional repressor to obtain signal inversion, and the output part was a fluorescent protein to be easily detected. The hybrid biosensor could specifically and positively correlate adenosylcobalamin concentrations to green fluorescent protein expression levels in vivo. This study also improved the operating concentration and dynamic range of the hybrid biosensor by systematic optimization. An individual cell harboring the hybrid biosensor presented over 20-fold higher fluorescence intensity than the negative control. Then, using such a biosensor combined with fluorescence-activated cell sorting, we established a high-throughput screening platform for screening adenosylcobalamin overproducers. This study demonstrates that this platform has significant potential to quickly isolate high-productive strains to meet industrial demand and that the framework is acceptable for various metabolites.