The advancement of tissue clearing technology has significantly propelled neuroscience research. Nevertheless, the fluorescent proteins used in traditional transgenic mouse strains were not specifically optimized for tissue clearing procedures, resulting in a substantial decrease in fluorescent intensity after clearing. In this study, we developed the Ci1 reporter mouse strain (where Ci stands for the Chinese Institute for Brain Research, CIBR) based on the bright red fluorescent protein mScarlet. The Ci1 reporter exhibits no fluorescence leakage in various organs or tissue types and can be readily crossed with multiple tissue-specific Cre lines. Compared to the Ai14 mouse strain, the Ci1 reporter strain demonstrates lower non-specific leakage, stronger fluorescence intensity in different tissues, and better preservation of fluorescence following tissue clearing treatment. The creation of the Ci1 reporter provides a more effective tool for both neuroscience and other biomedical research applications.
Animals ; Luminescent Proteins/metabolism* ; Mice, Transgenic ; Mice ; Red Fluorescent Protein ; Brain/metabolism* ; Genes, Reporter ; Fluorescence

Gene expression labeling and conditional manipulation of gene function are important for elaborate dissection of gene function. However, contemporary generation of pairwise dual-function knockin alleles to achieve both conditional and geno-tagging effects with a single donor has not been reported. Here we first developed a strategy based on a flipping donor named FoRe to generate conditional knockout alleles coupled with fluorescent allele-labeling through NHEJ-mediated unidirectional targeted insertion in zebrafish facilitated by the CRISPR/Cas system. We demonstrated the feasibility of this strategy at sox10 and isl1 loci, and successfully achieved Cre-induced conditional knockout of target gene function and simultaneous switch of the fluorescent reporter, allowing generation of genetic mosaics for lineage tracing. We then improved the donor design enabling efficient one-step bidirectional knockin to generate paired positive and negative conditional alleles, both tagged with two different fluorescent reporters. By introducing Cre recombinase, these alleles could be used to achieve both conditional knockout and conditional gene restoration in parallel; furthermore, differential fluorescent labeling of the positive and negative alleles enables simple, early and efficient real-time discrimination of individual live embryos bearing different genotypes prior to the emergence of morphologically visible phenotypes. We named our improved donor as Bi-FoRe and demonstrated its feasibility at the sox10 locus. Furthermore, we eliminated the undesirable bacterial backbone in the donor using minicircle DNA technology. Our system could easily be expanded for other applications or to other organisms, and coupling fluorescent labeling of gene expression and conditional manipulation of gene function will provide unique opportunities to fully reveal the power of emerging single-cell sequencing technologies.
Alleles ; Animals ; CRISPR-Cas Systems ; DNA End-Joining Repair ; DNA, Circular/metabolism* ; Embryo, Nonmammalian ; Gene Editing/methods* ; Gene Knock-In Techniques ; Gene Knockout Techniques ; Genes, Reporter ; Genetic Loci ; Genotyping Techniques ; Green Fluorescent Proteins/metabolism* ; Integrases/metabolism* ; Luminescent Proteins/metabolism* ; Mutagenesis, Insertional ; Single-Cell Analysis ; Zebrafish/metabolism*

Animals ; Antigens, Surface/genetics* ; Cell Communication/genetics* ; Copulation/physiology* ; Fallopian Tubes/metabolism* ; Female ; Fertilization/genetics* ; GPI-Linked Proteins/genetics* ; Gene Expression Regulation ; Genes, Reporter ; Green Fluorescent Proteins/metabolism* ; Litter Size ; Luminescent Proteins/metabolism* ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Mitochondria/metabolism* ; Reproduction/genetics* ; Signal Transduction ; Sperm Count ; Sperm Motility/genetics* ; Spermatozoa/metabolism* ; Uterus/metabolism*

Fluorescent proteins can be used as probes to investigate intercellular molecular interactions and trace the pathway of specific metabolites, thus providing a detailed and accurate description of various metabolic processes and cellular pathways in living cells. Nowadays, the existing fluorescent proteins cover almost all spectral bands from ultraviolet to far-red. These fluorescent proteins have been applied in many fields of bioscience with the help of high-resolution microscopy, making great contributions to the development of biology. It is generally agreed that orange fluorescent proteins refer to the fluorescent proteins at the spectral range of 540-570 nm. In recent years, researches on orange fluorescent proteins have made great progress, and they have been widely applied in the field of biology and medicine as reporter protein and fluorescence resonance energy transfer as fluorescent receptor. This paper reviews the studies in the field of orange fluorescent proteins over the last 15 years, with the special focus on the development and application of orange fluorescent proteins to provide the basis for the future studies.
Biosensing Techniques ; trends ; Fluorescence Resonance Energy Transfer ; Luminescent Proteins ; metabolism ; Research ; trends

Although extensively studied, the exact role of sleep in learning and memory is still not very clear. Sleep deprivation has been most frequently used to explore the effects of sleep on learning and memory, but the results from such studies are inevitably complicated by concurrent stress and distress. Furthermore, it is not clear whether there is a strict time-window between sleep and memory consolidation. In the present study we were able to induce time-locked slow-wave sleep (SWS) in mice by optogenetically stimulating GABAergic neurons in the parafacial zone (PZ), providing a direct approach to analyze the influences of SWS on learning and memory with precise time-windows. We found that SWS induced by light for 30 min immediately or 15 min after the training phase of the object-in-place task significantly prolonged the memory from 30 min to 6 h. However, induction of SWS 30 min after the training phase did not improve memory, suggesting a critical time-window between the induction of a brief episode of SWS and learning for memory consolidation. Application of a gentle touch to the mice during light stimulation to prevent SWS induction also failed to improve memory, indicating the specific role of SWS, but not the activation of PZ GABAergic neurons itself, in memory consolidation. Similar influences of light-induced SWS on memory consolidation also occurred for Y-maze spatial memory and contextual fear memory, but not for cued fear memory. SWS induction immediately before the test phase had no effect on memory performance, indicating that SWS does not affect memory retrieval. Thus, by induction of a brief-episode SWS we have revealed a critical time window for the consolidation of hippocampus-dependent memory.
Animals ; Cues ; Electroencephalography ; Electromyography ; Evoked Potentials, Motor ; physiology ; Fear ; psychology ; Glutamate Decarboxylase ; metabolism ; Hippocampus ; physiology ; Light ; Luminescent Proteins ; genetics ; metabolism ; Maze Learning ; physiology ; Memory Consolidation ; physiology ; Mice ; Mice, Inbred C57BL ; Mice, Transgenic ; Sleep Deprivation ; Sleep, Slow-Wave ; physiology ; Time Factors ; Vesicular Inhibitory Amino Acid Transport Proteins ; genetics ; metabolism

Drosophila dEAAT2, a member of the excitatory amino-acid transporter (EAAT) family, has been described as mediating the high-affinity transport of taurine, which is a free amino-acid abundant in both insects and mammals. However, the role of taurine and its transporter in hearing is not clear. Here, we report that dEAAT2 is required for the larval startle response to sound stimuli. dEAAT2 was found to be enriched in the distal region of chordotonal neurons where sound transduction occurs. The Ca imaging and electrophysiological results showed that disrupted dEAAT2 expression significantly reduced the response of chordotonal neurons to sound. More importantly, expressing dEAAT2 in the chordotonal neurons rescued these mutant phenotypes. Taken together, these findings indicate a critical role for Drosophila dEAAT2 in sound transduction by chordotonal neurons.
Acoustic Stimulation ; Action Potentials ; genetics ; Animals ; Animals, Genetically Modified ; Auditory Pathways ; physiology ; Calcium ; metabolism ; Drosophila ; genetics ; Drosophila Proteins ; genetics ; metabolism ; Excitatory Amino Acid Transporter 2 ; genetics ; metabolism ; Hearing ; genetics ; Larva ; Luminescent Proteins ; genetics ; metabolism ; Mutation ; genetics ; Nervous System ; cytology ; Neurons ; metabolism

The brain has very high energy requirements and consumes 20% of the oxygen and 25% of the glucose in the human body. Therefore, the molecular mechanism underlying how the brain metabolizes substances to support neural activity is a fundamental issue for neuroscience studies. A well-known model in the brain, the astrocyte-neuron lactate shuttle, postulates that glucose uptake and glycolytic activity are enhanced in astrocytes upon neuronal activation and that astrocytes transport lactate into neurons to fulfill their energy requirements. Current evidence for this hypothesis has yet to reach a clear consensus, and new concepts beyond the shuttle hypothesis are emerging. The discrepancy is largely attributed to the lack of a critical method for real-time monitoring of metabolic dynamics at cellular resolution. Recent advances in fluorescent protein-based sensors allow the generation of a sensitive, specific, real-time readout of subcellular metabolites and fill the current technological gap. Here, we summarize the development of genetically encoded metabolite sensors and their applications in assessing cell metabolism in living cells and in vivo, and we believe that these tools will help to address the issue of elucidating neural energy metabolism.
Animals ; Biosensing Techniques ; Brain ; cytology ; metabolism ; Cytological Techniques ; Energy Metabolism ; Humans ; Luminescent Proteins ; genetics ; metabolism ; Time Factors

Mounting evidence supports an important role of chemokines, produced by spinal cord astrocytes, in promoting central sensitization and chronic pain. In particular, CCL2 (C-C motif chemokine ligand 2) has been shown to enhance N-methyl-D-aspartate (NMDA)-induced currents in spinal outer lamina II (IIo) neurons. However, the exact molecular, synaptic, and cellular mechanisms by which CCL2 modulates central sensitization are still unclear. We found that spinal injection of the CCR2 antagonist RS504393 attenuated CCL2- and inflammation-induced hyperalgesia. Single-cell RT-PCR revealed CCR2 expression in excitatory vesicular glutamate transporter subtype 2-positive (VGLUT2) neurons. CCL2 increased NMDA-induced currents in CCR2/VGLUT2 neurons in lamina IIo; it also enhanced the synaptic NMDA currents evoked by dorsal root stimulation; and furthermore, it increased the total and synaptic NMDA currents in somatostatin-expressing excitatory neurons. Finally, intrathecal RS504393 reversed the long-term potentiation evoked in the spinal cord by C-fiber stimulation. Our findings suggest that CCL2 directly modulates synaptic plasticity in CCR2-expressing excitatory neurons in spinal lamina IIo, and this underlies the generation of central sensitization in pathological pain.
Animals ; Benzoxazines ; pharmacology ; therapeutic use ; Chemokine CCL2 ; antagonists & inhibitors ; genetics ; metabolism ; pharmacology ; Excitatory Amino Acid Agents ; pharmacology ; Excitatory Amino Acid Agonists ; pharmacology ; Female ; Freund's Adjuvant ; toxicity ; Hyperalgesia ; chemically induced ; metabolism ; prevention & control ; Long-Term Potentiation ; drug effects ; physiology ; Luminescent Proteins ; genetics ; metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Transgenic ; Myelitis ; chemically induced ; drug therapy ; metabolism ; Neurons ; drug effects ; Pain Management ; Somatostatin ; genetics ; metabolism ; Spinal Cord ; cytology ; Spiro Compounds ; pharmacology ; therapeutic use ; Vesicular Glutamate Transport Protein 2 ; genetics ; metabolism ; Vesicular Inhibitory Amino Acid Transport Proteins ; genetics ; metabolism

OBJECTIVETo establish red-green dual-color fluorescence glioma model in nude mice and to explore its practical values.

METHODSCM-DiI-stained rat glioma C6 cells (C6-CM- DiI cells) expressing red fluorescence were inoculated into the brain of athymic nude mice expressing green fluorescence protein (NC-C57BL/6J-EGFP). Then the whole-body dual-color fluorescence imaging was detected dynamically. Finally whole brains of the tumor-bearing mice were removed and 5 µm thick serial frozen slices were made. Light microscopy, fluorescence microscopy and confocal laser scanning microscopy were performed to observe the transplanted tumor tissue structure and fluorescent cells.

RESULTSTumor mass with red fluorescence increased gradually under continuous in-vivo fluorescence imaging monitoring. Under the fluorescence microscope, cells with red, green and yellow fluorescence were observed in the frozen sections of transplanted tumor tissue and the mutual structural relationship among them could be defined. The tumor cells migration, implantation and cell fusion between transplanted tumor cells and host cells could be observed. It could be distinguished according to the fluorescence, that blood vessels of tumor-origin displayed red fluorescence, blood vessels of host-origin displayed green fluorescence and mosaic blood vessels appeared yellow fluorescence. It was depicted that host innate astrocytes and oligodendrocytes in the microenvironment at the tumor periphery could be activated and dedifferentiated into nestin-positive cells.

CONCLUSIONSIn contrast to traditional animal model, the dual-color fluorescence imaging of nude mouse models of glioma possesses enormous advantages in investigating tumor mass in-vivo fluorescence imaging, tumor cells migration and metastasis, tumor angiogenesis and reactive activation of host innate cells in the microenvironment at tumor periphery, thus, has highly practical application value.

Animals ; Astrocytes ; metabolism ; Brain Neoplasms ; blood supply ; metabolism ; pathology ; ultrastructure ; Carbocyanines ; metabolism ; Cell Fusion ; Cell Line, Tumor ; Cell Movement ; Disease Models, Animal ; Fluorescent Dyes ; metabolism ; Glioma ; blood supply ; metabolism ; pathology ; ultrastructure ; Green Fluorescent Proteins ; metabolism ; Luminescent Proteins ; metabolism ; Mice ; Mice, Inbred C57BL ; Mice, Nude ; Microscopy, Confocal ; Microscopy, Fluorescence ; Neoplasm Transplantation ; Neovascularization, Pathologic ; Nestin ; metabolism ; Oligodendroglia ; metabolism ; Rats

We established an orthotopic non-muscle invasive bladder cancer (NMIBC) mouse model expressing the mammalian target of the rapamycin (mTOR) signaling pathway. After intravesical instillation of KU-7-lucs (day 0), animals were subsequently monitored by bioluminescence imaging (BLI) on days 4, 7, 14, and 21, and performed histopathological examination. We also validated the orthotopic mouse model expressing the mTOR signaling pathway immunohistochemically. In vitro BLI photon density was correlated with KU-7-luc cell number (r2 = 0.97, P < 0.01) and in vivo BLI photon densities increased steadily with time after intravesical instillation. The tumor take rate was 84.2%, formed initially on day 4 and remained NMIBC up to day 21. T1 photon densities were significantly higher than Ta (P < 0.01), and histological tumor volume was positively correlated with BLI photon density (r2 = 0.87, P < 0.01). The mTOR signaling pathway-related proteins were expressed in the bladder, and were correlated with the western blot results. Our results suggest successful establishment of an orthotopic mouse NMIBC model expressing the mTOR signaling pathway using KU-7-luc cells. This model is expected to be helpful to evaluate preclinical testing of intravesical therapy based on the mTOR signaling pathway against NMIBC.
Animals ; Blotting, Western ; Cell Line, Tumor ; Disease Models, Animal ; Female ; Genes, Reporter ; Green Fluorescent Proteins/genetics/metabolism ; Humans ; Immunohistochemistry ; Luciferases, Firefly/genetics ; Luminescent Measurements ; Mice ; Mice, Nude ; Neoplasm Staging ; *Signal Transduction ; TOR Serine-Threonine Kinases/*metabolism ; Transplantation, Heterologous ; Urinary Bladder Neoplasms/*metabolism/pathology/veterinary