Name: in vivo monitoring of circadian clock gene expression in the mouse suprachiasmatic nucleus using fluorescence reporters
Uploaded: 2018-07-04T12:30:00
Description: Watch this Scientific Journal Video about In Vivo Monitoring of Circadian Clock Gene Expression in the Mouse Suprachiasmatic Nucleus Using Fluorescence Reporters at JoVE.com

We thank members in the Zhang lab for providing stimulating discussions and members in the Zhan lab for providing technical assistance. This research was supported by grants 31500860 (to C.Z.) of the NSFC, 2012CB837700 (to E.E.Z. and C.Z.) of the 973 Program from the M.O.S.T. of China, and by funding from the Beijing Municipal Government. E.E.Z. was supported by the Chinese &#34;Recruitment Program of Global Youth Experts&#34;.

All procedures in this protocol were conducted with the approval of the Institutional Animal Care and Use Committee (IACUC) of the National Institute of Biological Sciences, Beijing, in accordance with the governmental regulations of China.
1. Construction of the Cry1 Fluorescence Reporter
Note: Previous circadian studies using the bioluminescence system2,12,13 fuse ...

<ol>
	<li>Welsh, D. K., Takahashi, J. S., Kay, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Suprachiasmatic+nucleus:+cell+autonomy+and+network+properties.">Suprachiasmatic nucleus: cell autonomy and network properties.</a> Annual Review of Physiology. 72, 551-577 (2010).</li><li>Zhang, E. E., Kay, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clocks+not+winding+down:+unravelling+circadian+networks.">Clocks not winding down: unravelling circadian networks.</a> Nature Reviews Molecular Cell Biology. 11, 764-776 (2010).</li><li>Takahashi, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcriptional+architecture+of+the+mammalian+circadian+clock.">Transcriptional architecture of the mammalian circadian clock.</a> Nature Reviews Genetics. 18, 164-179 (2017).</li><li>Yoo, S. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PERIOD2::LUCIFERASE+real-time+reporting+of+circadian+dynamics+reveals+persistent+circadian+oscillations+in+mouse+peripheral+tissues.">PERIOD2::LUCIFERASE real-time reporting of circadian dynamics reveals persistent circadian oscillations in mouse peripheral tissues.</a> Proceedings of the National Academy of Sciences U S A. 101, 5339-5346 (2004).</li><li>Davidson, A. J., Castanon-Cervantes, O., Leise, T. L., Molyneux, P. C., Harrington, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualizing+jet+lag+in+the+mouse+suprachiasmatic+nucleus+and+peripheral+circadian+timing+system.">Visualizing jet lag in the mouse suprachiasmatic nucleus and peripheral circadian timing system.</a> European Journal of Neuroscience. 29, 171-180 (2009).</li><li>Savelyev, S. A., Larsson, K. C., Johansson, A. S., Lundkvist, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Slice+preparation,+organotypic+tissue+culturing+and+luciferase+recording+of+clock+gene+activity+in+the+suprachiasmatic+nucleus.">Slice preparation, organotypic tissue culturing and luciferase recording of clock gene activity in the suprachiasmatic nucleus.</a> Journal of Visualized Experiments. (48), (2011).</li><li>Yamaguchi, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+expression:+View+of+a+mouse+clock+gene+ticking.">Gene expression: View of a mouse clock gene ticking.</a> Nature. 409, 684-684 (2001).</li><li>Ono, D., Honma, K. I., Honma, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Circadian+and+ultradian+rhythms+of+clock+gene+expression+in+the+suprachiasmatic+nucleus+of+freely+moving+mice.">Circadian and ultradian rhythms of clock gene expression in the suprachiasmatic nucleus of freely moving mice.</a> Science Reports. 5, 12310 (2015).</li><li>Ono, D., Honma, S., Honma, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Circadian+PER2::LUC+rhythms+in+the+olfactory+bulb+of+freely+moving+mice+depend+on+the+suprachiasmatic+nucleus+but+not+on+behaviour+rhythms.">Circadian PER2::LUC rhythms in the olfactory bulb of freely moving mice depend on the suprachiasmatic nucleus but not on behaviour rhythms.</a> European Journal of Neuroscience. 42, 3128-3137 (2015).</li><li>Ono, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dissociation+of+Per1+and+Bmal1+circadian+rhythms+in+the+suprachiasmatic+nucleus+in+parallel+with+behavioral+outputs.">Dissociation of Per1 and Bmal1 circadian rhythms in the suprachiasmatic nucleus in parallel with behavioral outputs.</a> Proceedings of the National Academy of Sciences U S A. 114, E3699-E3708 (2017).</li><li>Reppert, S. M., Weaver, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coordination+of+circadian+timing+in+mammals.">Coordination of circadian timing in mammals.</a> Nature. 418, 935-941 (2002).</li><li>Liu, A. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Redundant+function+of+REV-ERBalpha+and+beta+and+non-essential+role+for+Bmal1+cycling+in+transcriptional+regulation+of+intracellular+circadian+rhythms.">Redundant function of REV-ERBalpha and beta and non-essential role for Bmal1 cycling in transcriptional regulation of intracellular circadian rhythms.</a> PLoS Genetics. 4, e1000023 (2008).</li><li>Maywood, E. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+core+circadian+feedback+loop+in+suprachiasmatic+nucleus+of+mCry1-luc+transgenic+reporter+mouse.">Analysis of core circadian feedback loop in suprachiasmatic nucleus of mCry1-luc transgenic reporter mouse.</a> Proceedings of the National Academy of Sciences U S A. 110, 9547-9552 (2013).</li><li>Ukai-Tadenuma, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Delay+in+feedback+repression+by+cryptochrome+1+is+required+for+circadian+clock+function.">Delay in feedback repression by cryptochrome 1 is required for circadian clock function.</a> Cell. 144, 268-281 (2011).</li><li>McClure, C., Cole, K. L., Wulff, P., Klugmann, M., Murray, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+and+titering+of+recombinant+adeno-associated+viral+vectors.">Production and titering of recombinant adeno-associated viral vectors.</a> Journal of Visualized Experiments. 57, e3348 (2011).</li><li>Yamaguchi, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mice+genetically+deficient+in+vasopressin+V1a+and+V1b+receptors+are+resistant+to+jet+lag.">Mice genetically deficient in vasopressin V1a and V1b receptors are resistant to jet lag.</a> Science. 342, 85-90 (2013).</li><li>Nagano, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+abrupt+shift+in+the+day/night+cycle+causes+desynchrony+in+the+mammalian+circadian+center.">An abrupt shift in the day/night cycle causes desynchrony in the mammalian circadian center.</a> Journal of Neuroscience. 23, 6141-6151 (2003).</li><li>Golombek, D. A., Rosenstein, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physiology+of+Circadian+Entrainment.">Physiology of Circadian Entrainment.</a> Physiological Reviews. 90, 1063-1102 (2010).</li><li>Mei, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Long-term+in+vivo+recording+of+circadian+rhythms+in+brains+of+freely+moving+mice.">Long-term in vivo recording of circadian rhythms in brains of freely moving mice.</a> Proceedings of the National Academy of Sciences. 115, 4276-4281 (2018).</li></ol>

In contrast to ex vivo methods, such as slice culture4,5, RT-PCR16, and in situ hybridization17, which require that animals be killed, the in vivo recording method allows investigators to study circadian gene expression in a living animal. As such, this technology provides the ability to evaluate the effect of different physical perturbations (e.g., sleep deprivation, stress, food...

In mammals, the suprachiasmatic nucleus (SCN) governs the whole body&#39;s circadian rhythm to coordinate an individual&#39;s response to exogenous environmental changes (e.g., light, temperature, stress, etc.)1. Core clock components consist of Per1-3, Cry1-2, Clock, and Bmal1, and play a central role in regulating the circadian clock of each cell. Each cell in the SCN contains the transcriptional activator, CLOCK/BMAL1, which acts as a heterodimer to induce the expression of PER and CRY. The PER/CRY complex then inhibits the function of CLOCK/BMAL1 to form a transcription-translation feedback loop that takes about 24 h to complete2,3.
Previous studies on the SCN have mainly employed the ex vivo SCN slice culture method4,5,6 and, while this approach has provided valuable information, its limitations have inhibited our ability to obtain data regarding the influence of other brain nuclei on the SCN, as well as the effect of exogenous stimuli (e.g., light) on cells residing in this critical region. In 2001, Hitoshi Okamura&#39;s group was the first to use the bioluminescence system to in vivo monitor circadian clock gene expression in the SCN in freely moving mice7. Ken-ichi Honma&#39;s group has spent the past few years further developing the bioluminescence in vivo recording system in the SCN8,9,10. Together, these studies have provided researchers with the ability to monitor the circadian clock in constant darkness or after a light pulse. However, because bioluminescence is too dim to allow for continuous monitoring during the light/dark cycle, coupled with the fact that light is the predominant signal required for the SCN-mediated entrainment of circadian clocks11, there is increasing demand for the development of experimental methods which overcome the limitations associated with bioluminescence recording. The current report describes a fluorescence-based system which was constructed to monitor the circadian clock of the SCN in vivo in freely moving mice. This easy-to-use method permits continuous monitoring during the light/dark cycle and allows for the long-term observation of the transcription of circadian clock genes in the SCN in real-time and at high temporal resolution.

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in vivo monitoring of circadian clock gene expression in the mouse suprachiasmatic nucleus using fluorescence reporters

This technique combines optical fiber mediated fluorescence recordings with the precise delivery of recombinant adeno-associated virus based gene reporters. This new and easy to use in vivo fluorescence monitoring system was developed to record the transcriptional rhythm of the clock gene, Cry1, in the suprachiasmatic nucleus (SCN) of freely moving mice. To do so, a Cry1 transcription fluorescence reporter was designed and packaged into Adeno-associated virus. Purified, concentrated virus was injected into the mouse SCN followed by the insertion of an optic fiber, which was then fixed onto the surface of the brain. The animals were returned to their home cages and allowed a 1-month post-operative recovery period to ensure sufficient reporter expression. Fluorescence was then recorded in freely moving mice via an in vivo monitoring system that was constructed at our institution. For the in vivo recording system, a 488 nm laser was coupled with a 1 &#215; 4 beam-splitter that divided the light into four laser excitation outputs of equal power. This setup enabled us to record from four animals simultaneously. Each of the emitted fluorescence signals was collected via a photomultiplier tube and a data acquisition card. In contrast to the previous bioluminescence in vivo circadian clock recording technique, this fluorescence in vivo recording system allowed the recording of circadian clock gene expression during the light cycle.

Fluorescence reporter design of Cry1 was show in Figure 1A. Using the approach detailed above, 500 nL of rAAV-P(Cry1)-intron336-Venus-NLS-D2 was successfully injected into the SCN of an adult mouse, and exhibited robust Venus expression (Figure 1B, 1C). Fluorescence signals recorded under 12h/12h light/dark (LD) and dark/dark (DD) conditions (Figure 2) yielded robus...

Watch this Scientific Journal Video about In Vivo Monitoring of Circadian Clock Gene Expression in the Mouse Suprachiasmatic Nucleus Using Fluorescence Reporters at JoVE.com

In Vivo Monitoring of Circadian Clock Gene Expression in the Mouse Suprachiasmatic Nucleus Using Fluorescence Reporters

This newly developed fluorescence-based technology enables long-term monitoring of the transcription of circadian clock genes in the suprachiasmatic nucleus (SCN) of freely moving mice in real-time and at a high temporal resolution.

In Vivo Monitoring of Circadian Clock Gene Expression in the Mouse Suprachiasmatic Nucleus Using Fluorescence Reporters

This technique combines optical fiber mediated fluorescence recordings with the precise delivery of recombinant adeno-associated virus based gene ...

This method provides a way to monitor the circadian clock gene expression in real time in high temporal resolution in freely moving mice. The main advantage of this technique is that it works in both light-dark, and dark-dark conditions, which are critically important for circadian clock studies. Using an optical fiber knife, cut a fiber 17 millimeters in length.Making sure that each side of the optic fiber is smooth. Insert the optic fiber into the ceramic ferrule and fix the optic fiber to a ceramic ferrule with methyl ethyl ketone peroxide. Ensuring that the surfaces of the optic fiber and ceramic ferrule are flush.Clean the optic fiber with a cotton swab soaked with 75%ethnol. And keep it clean until ready for insertion. Begin the injection procedure by first loading five microliters of recombinant AAV into a microsyringe.Then after anesthetizing an adult mouse using an institutionally approved protocol, check for a sufficient depth of anesthesia by the lack of a toe pinch response. Next, use scissors to remove fur from the head of the mouse. And then mount the head of the mouse into a stereotaxic apparatus.After making an incision in the scalp, expose the skull. And adjust the stereotaxic apparatus so that bregma and lambda are in the same horizontal plane. Then use a cotton swab soaked in 4%hydrogen peroxide and water, to corrode the brain periosteum.Followed with a clean cotton swab to clear and dry the surface of the skull. Using the stereotaxic arm, identify the surgical site, 0.46 millimeters posterior and 0.25 millimeter lateral to bregma. Then using a micro drill, make a hole, about one millimeter in diameter at this point.Use a clear cotton swab with physiological saline solution to clear bone fragments from the exposed surface of the brain. Next, insert a microsyringe into the brain to a depth of 5.7 millimeters from the surface of the skull. And inject 500 nanoliters of recombinant AAV at a rate of 50 nanoliters per minute into the SCN.Leave the microsyringe in place for 10 minutes after the injection to ensure complete diffusion of recombinant AAV. After 10 minutes, slowly withdraw the microsyringe. Immediately after recombinant AAV injection, insert the ceramic ferrule containing the optic fiber, into the SCN.Then fix the ceramic ferrule and optical fiber onto the skull using dental resin and allow to dry. After drying, smear the surface of the dental resin with black nail polish. Place the mouse in a warmed recovery cage and monitor it, as it comes out of anesthesia.Once the animal has regained a sternal recumbency, it can be single housed and returned to the housing room with a 12 hour light-dark cycle. Eight days after surgery, measure the florescent signal in the SCN of sham operated control mice to establish the background signal. First, connect the fiber on the mouse head, with the fluorescent signal monitor.Set the software to measure the florescence for 15 seconds every 10 minutes at a frequency of 100 hertz. Record the signal from the sham injected mouse. Repeat the process to evaluate the fluorescent signal of mice injected with the recombinant AAV crypto chrome reporter.Exclude mice which have received the viral vector, but only display background signal as this likely indicates the the tip of the optic fiber has missed the SCN. After these initial measures, return the mice to their home cages for another three weeks, to allow the fluorescent signal to stabilize. At the conclusion of the experiment, check the placement of the optic fiber in the fixed brains.Exclude mice from analysis if the optic fiber tip is not correctly implanted in the SCN. Using the approach detailed above, 500 nanoliters of virus harboring the crypto chrome gene reporter was successfully injected into the SCN of an adult mouse. Robust venus expression was seen eight days after the virus injection.This magnified image demonstrates the high level of venus expression in the SCN. Background florescence in the SCN for a sham operated animal during light on and light off periods is seen here. This animal showed no detectable rhythm under both light-dark and dark-dark conditions.This image shows crypto chrome gene reporter expression over the course of seven days in a 12, 12 light-dark condition. And over seven days in a dark-dark condition. This image shows analysis of circadian rhythm in the light-dark condition.The red line indicates the converged fit in the sin curve. The result of which is shown here. Analysis of circadian rhythm in the dark-dark condition is shown here.Again, the red line indicates the converged fit in the sin curve. And the result of the fit is shown here.

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Research

JoVE Journal

Neuroscience

Slice Preparation, Organotypic Tissue Culturing and Luciferase Recording of Clock Gene Activity in the Suprachiasmatic Nucleus

A central circadian (~24 hr) clock coordinating daily rhythms in physiology and behavior resides in the suprachiasmatic nucleus (SCN) located in the anterior hypothalamus. The clock is directly synchronized by light via the retina and optic nerve. Circadian oscillations are generated by interacting negative feedback loops of a number of so called "clock genes" and their protein products, including the Period (Per) genes. The core clock is also dependent on membrane depolarization, calcium and cAMP 1. The SCN shows daily oscillations in clock gene expression, metabolic activity and spontaneous electrical activity. Remarkably, this endogenous cyclic activity persists in adult tissue slices of the SCN 2-4. In this way, the biological clock can easily be studied in vitro, allowing molecular, electrophysiological and metabolic investigations of the pacemaker function.
The SCN is a small, well-defined bilateral structure located right above the optic chiasm 5. In the rat it contains ~8.000 neurons in each nucleus and has dimensions of approximately 947 &mu;m (length, rostrocaudal axis) x 424 &mu;m (width) x 390 &mu;m (height) 6. To dissect out the SCN it is necessary to cut a brain slice at the specific level of the brain where the SCN can be identified. Here, we describe the dissecting and slicing procedure of the SCN, which is similar for mouse and rat brains. Further, we show how to culture the dissected tissue organotypically on a membrane 7, a technique developed for SCN tissue culture by Yamazaki et al. 8. Finally, we demonstrate how transgenic tissue can be used for measuring expression of clock genes/proteins using dynamic luciferase reporter technology, a method that originally was used for circadian measurements by Geusz et al. 9. We here use SCN tissues from the transgenic knock-in PERIOD2::LUCIFERASE mice produced by Yoo et al. 10. The mice contain a fusion protein of PERIOD (PER) 2 and the firefly enzyme LUCIFERASE. When PER2 is translated in the presence of the substrate for luciferase, i.e. luciferin, the PER2 expression can be monitored as bioluminescence when luciferase catalyzes the oxidation of luciferin. The number of emitted photons positively correlates to the amount of produced PER2 protein, and the bioluminescence rhythms match the PER2 protein rhythm in vivo 10. In this way the cyclic variation in PER2 expression can be continuously monitored real time during many days. The protocol we follow for tissue culturing and real-time bioluminescence recording has been thoroughly described by Yamazaki and Takahashi 11.

The procedure of preparing slices containing the adult mouse hypothalamic suprachiasmatic nucleus (SCN), and a rapid way to culture the SCN tissue in organotypic culture condition, are reported. Further, the measurement of oscillatory clock gene protein expression using dynamic luciferase reporter technology is described.

A central circadian (~24 hr) clock coordinating daily rhythms in physiology and behavior resides in the suprachiasmatic nucleus (SCN) located in the ...

Spinal Cord Electrophysiology II: Extracellular Suction Electrode Fabrication

Development of neural circuitries and locomotion can be studied using neonatal rodent spinal cord central pattern generator (CPG) behavior. We demonstrate a method to fabricate suction electrodes that are used to examine CPG activity, or fictive locomotion, in dissected rodent spinal cords. The rodent spinal cords are placed in artificial cerebrospinal fluid and the ventral roots are drawn into the suction electrode. The electrode is constructed by modifying a commercially available suction electrode. A heavier silver wire is used instead of the standard wire given by the commercially available electrode. The glass tip on the commercial electrode is replaced with a plastic tip for increased durability. We prepare hand drawn electrodes and electrodes made from specific sizes of tubing, allowing consistency and reproducibility. Data is collected using an amplifier and neurogram acquisition software. Recordings are performed on an air table within a Faraday cage to prevent mechanical and electrical interference, respectively.

A demonstration of the fabrication and use of an extracellular suction electrode used to measure electrophysiological recordings of neonatal rodent spinal cords in vitro

Development of neural circuitries and locomotion can be studied using neonatal rodent spinal cord central pattern generator (CPG) behavior. We demonstrate ...

Transfection of Mouse Retinal Ganglion Cells by in vivo Electroporation

The targeting and refinement of RGC projections to the midbrain is a popular and powerful model system for studying how precise patterns of neural connectivity form during development. In mice, retinofugal projections are arranged in a topographic manner and form eye-specific layers in the Lateral Geniculate Nucleus (dLGN) of the thalamus and the Superior Colliculus (SC). The development of these precise patterns of retinofugal projections has typically been studied by labeling populations of RGCs with fluorescent dyes and tracers, such as horseradish peroxidase1-4. However, these methods are too coarse to provide insight into developmental changes in individual RGC axonal arbor morphology that are the basis of retinotopic map formation. They also do not allow for the genetic manipulation of RGCs.
Recently, electroporation has become an effective method for providing precise spatial and temporal control for delivery of charged molecules into the retina5-11. Current retinal electroporation protocols do not allow for genetic manipulation and tracing of retinofugal projections of a single or small cluster of RGCs in postnatal mice. It has been argued that postnatal in vivo electroporation is not a viable method for transfecting RGCs since the labeling efficiency is extremely low and hence requires targeting at embryonic ages when RGC progenitors are undergoing differentiation and proliferation6. 
In this video we describe an in vivo electroporation protocol for targeted delivery of genes, shRNA, and fluorescent dextrans to murine RGCs postnatally. This technique provides a cost effective, fast and relatively easy platform for efficient screening of candidate genes involved in several aspects of neural development including axon retraction, branching, lamination, regeneration and synapse formation at various stages of circuit development. In summary we describe here a valuable tool which will provide further insights into the molecular mechanisms underlying sensory map development.

Transfection of Mouse Retinal Ganglion Cells by in vivo Electroporation

We demonstrate an in vivo electroporation protocol for transfecting single or small clusters of retinal ganglion cells (RGCs) and other retinal cell types in postnatal mice over a wide range of ages. The ability to label and genetically manipulate postnatal RGCs in vivo is a powerful tool for developmental studies.

The targeting and refinement of RGC projections to the midbrain is a popular and powerful model system for studying how precise patterns of neural ...

Non-Laser Capture Microscopy Approach for the Microdissection of Discrete Mouse Brain Regions for Total RNA Isolation and Downstream Next-Generation Sequencing and Gene Expression Profiling

As technological platforms, approaches such as next-generation sequencing, microarray, and qRT-PCR have great promise for expanding our understanding of the breadth of molecular regulation. Newer approaches such as high-resolution RNA sequencing (RNA-Seq)1 provides new and expansive information about tissue- or state-specific expression such as relative transcript levels, alternative splicing, and micro RNAs2-4. Prospects for employing the RNA-Seq method in comparative whole transcriptome profiling5 within discrete tissues or between phenotypically distinct groups of individuals affords new avenues for elucidating molecular mechanisms involved in both normal and abnormal physiological states. Recently, whole transcriptome profiling has been performed on human brain tissue, identifying gene expression differences associated with disease progression6. However, the use of next-generation sequencing has yet to be more widely integrated into mammalian studies.
Gene expression studies in mouse models have reported distinct profiles within various brain nuclei using laser capture microscopy (LCM) for sample excision7,8. While LCM affords sample collection with single-cell and discrete brain region precision, the relatively low total RNA yields from the LCM approach can be prohibitive to RNA-Seq and other profiling approaches in mouse brain tissues and may require sub-optimal sample amplification steps. Here, a protocol is presented for microdissection and total RNA extraction from discrete mouse brain regions. Set-diameter tissue corers are used to isolate 13 tissues from 750-&mu;m serial coronal sections of an individual mouse brain. Tissue micropunch samples are immediately frozen and archived. Total RNA is obtained from the samples using magnetic bead-enabled total RNA isolation technology. Resulting RNA samples have adequate yield and quality for use in downstream expression profiling. This microdissection strategy provides a viable option to existing sample collection strategies for obtaining total RNA from discrete brain regions, opening possibilities for new gene expression discoveries.

Non-Laser Capture Microscopy Approach for the Microdissection of Discrete Mouse Brain Regions for Total RNA Isolation and Downstream Next-Generation Sequencing and Gene Expression Profiling  |

RNA expression profiling of discrete mouse brain regions requires a precise and repeatable tissue collection strategy. A protocol that uses both coronal brain sectioning and tissue corer-assisted microdissection is described here. The yield and quality of total RNA obtained from the resulting samples confirms the utility of the outlined method.

As technological platforms, approaches such as next-generation sequencing, microarray, and qRT-PCR have great promise for expanding our understanding of ...

Gene Transfer to the Developing Mouse Inner Ear by In Vivo Electroporation

The mammalian inner ear has 6 distinct sensory epithelia: 3 cristae in the ampullae of the semicircular canals; maculae in the utricle and saccule; and the organ of Corti in the coiled cochlea. The cristae and maculae contain vestibular hair cells that transduce mechanical stimuli to subserve the special sense of balance, while auditory hair cells in the organ of Corti are the primary transducers for hearing 1. Cell fate specification in these sensory epithelia and morphogenesis of the semicircular canals and cochlea take place during the second week of gestation in the mouse and are largely completed before birth 2,3. Developmental studies of the mouse inner ear are routinely conducted by harvesting transgenic embryos at different embryonic or postnatal stages to gain insight into the molecular basis of cellular and/or morphological phenotypes 4,5. We hypothesize that gene transfer to the developing mouse inner ear in utero in the context of gain- and loss-of-function studies represents a complimentary approach to traditional mouse transgenesis for the interrogation of the genetic mechanisms underlying mammalian inner ear development6.
The experimental paradigm to conduct gene misexpression studies in the developing mouse inner ear demonstrated here resolves into three general steps: 1) ventral laparotomy; 2) transuterine microinjection; and 3) in vivo electroporation. Ventral laparotomy is a mouse survival surgical technique that permits externalization of the uterus to gain experimental access to the implanted embryos7. Transuterine microinjection is the use of beveled, glass capillary micropipettes to introduce expression plasmid into the lumen of the otic vesicle or otocyst. In vivo electroporation is the application of square wave, direct current pulses to drive expression plasmid into progenitor cells8-10. 
We previously described this electroporation-based gene transfer technique and included detailed notes on each step of the protocol11. Mouse experimental embryological techniques can be difficult to learn from prose and still images alone. In the present work, we demonstrate the 3 steps in the gene transfer procedure. Most critically, we deploy digital video microscopy to show precisely how to: 1) identify embryo orientation in utero; 2) reorient embryos for targeting injections to the otocyst; 3) microinject DNA mixed with tracer dye solution into the otocyst at embryonic days 11.5 and 12.5; 4) electroporate the injected otocyst; and 5) label electroporated embryos for postnatal selection at birth. We provide representative examples of successfully transfected inner ears; a pictorial guide to the most common causes of otocyst mistargeting; discuss how to avoid common methodological errors; and present guidelines for writing an in utero gene transfer animal care protocol.

Gene Transfer to the Developing Mouse Inner Ear by In Vivo Electroporation

The mouse inner ear is a placode-derived sensory organ whose developmental program is elaborated during gestation. We define an in utero gene transfer technique consisting of three steps: mouse ventral laparotomy, transuterine microinjection, and in vivo electroporation. We use digital video microscopy to demonstrate the critical experimental embryological techniques.

The mammalian inner ear has 6 distinct sensory epithelia: 3 cristae in the ampullae of the semicircular canals; maculae in the utricle and saccule; and ...

High-resolution Live Imaging of Cell Behavior in the Developing Neuroepithelium

The embryonic spinal cord consists of cycling neural progenitor cells that give rise to a large percentage of the neuronal and glial cells of the central nervous system (CNS). Although much is known about the molecular mechanisms that pattern the spinal cord and elicit neuronal differentiation1, 2, we lack a deep understanding of these early events at the level of cell behavior. It is thus critical to study the behavior of neural progenitors in real time as they undergo neurogenesis.
In the past, real-time imaging of early embryonic tissue has been limited by cell/tissue viability in culture as well as the phototoxic effects of fluorescent imaging. Here we present a novel assay for imaging such tissue for long periods of time, utilizing a novel ex vivo slice culture protocol and wide-field fluorescence microscopy (Fig. 1). This approach achieves long-term time-lapse monitoring of chick embryonic spinal cord progenitor cells with high spatial and temporal resolution.
This assay may be modified to image a range of embryonic tissues3, 4 In addition to the observation of cellular and sub-cellular behaviors, the development of novel and highly sensitive reporters for gene activity (for example, Notch signaling5) makes this assay a powerful tool with which to understand how signaling regulates cell behavior during embryonic development.

Imaging embryonic tissue in real-time is challenging over long periods of time. Here we present an assay for monitoring cellular and sub-cellular changes in chick spinal cord for long periods with high spatial and temporal resolution. This technique can be adapted for other regions of the nervous system and developing embryo.

The embryonic spinal cord consists of cycling neural progenitor cells that give rise to a large percentage of the neuronal and glial cells of the central ...

Functional Neuroimaging Using Ultrasonic Blood-brain Barrier Disruption and Manganese-enhanced MRI

Although mice are the dominant model system for studying the genetic and molecular underpinnings of neuroscience, functional neuroimaging in mice remains technically challenging. One approach, Activation-Induced Manganese-enhanced MRI (AIM MRI), has been used successfully to map neuronal activity in rodents 1-5. In AIM MRI, Mn2+ acts a calcium analog and accumulates in depolarized neurons 6,7. Because Mn2+ shortens the T1 tissue property, regions of elevated neuronal activity will enhance in MRI. Furthermore, Mn2+ clears slowly from the activated regions; therefore, stimulation can be performed outside the magnet prior to imaging, enabling greater experimental flexibility. However, because Mn2+ does not readily cross the blood-brain barrier (BBB), the need to open the BBB has limited the use of AIM MRI, especially in mice.
One tool for opening the BBB is ultrasound. Though potentially damaging, if ultrasound is administered in combination with gas-filled microbubbles (i.e., ultrasound contrast agents), the acoustic pressure required for BBB opening is considerably lower. This combination of ultrasound and microbubbles can be used to reliably open the BBB without causing tissue damage 8-11.
Here, a method is presented for performing AIM MRI by using microbubbles and ultrasound to open the BBB. After an intravenous injection of perflutren microbubbles, an unfocused pulsed ultrasound beam is applied to the shaved mouse head for 3 minutes. For simplicity, we refer to this technique of BBB Opening with Microbubbles and UltraSound as BOMUS 12. Using BOMUS to open the BBB throughout both cerebral hemispheres, manganese is administered to the whole mouse brain. After experimental stimulation of the lightly sedated mice, AIM MRI is used to map the neuronal response.
To demonstrate this approach, herein BOMUS and AIM MRI are used to map unilateral mechanical stimulation of the vibrissae in lightly sedated mice 13. Because BOMUS can open the BBB throughout both hemispheres, the unstimulated side of the brain is used to control for nonspecific background stimulation. The resultant 3D activation map agrees well with published representations of the vibrissae regions of the barrel field cortex 14. The ultrasonic opening of the BBB is fast, noninvasive, and reversible; and thus this approach is suitable for high-throughput and/or longitudinal studies in awake mice.

A technique is described for broadly opening the blood-brain barrier in the mouse using microbubbles and ultrasound. Using this technique, manganese can be administered to the mouse brain. Because manganese is an MRI contrast agent that accumulates in depolarized neurons, this approach enables imaging of neuronal activity.

Although mice are the dominant model system for studying the genetic and molecular underpinnings of neuroscience, functional neuroimaging in mice remains ...

Micromanipulation of Gene Expression in the Adult Zebrafish Brain Using Cerebroventricular Microinjection of Morpholino Oligonucleotides

Manipulation of gene expression in tissues is required to perform functional studies. In this paper, we demonstrate the cerebroventricular microinjection (CVMI) technique as a means to modulate gene expression in the adult zebrafish brain. By using CVMI, substances can be administered into the cerebroventricular fluid and be thoroughly distributed along the rostrocaudal axis of the brain. We particularly focus on the use of antisense morpholino oligonucleotides, which are potent tools for knocking down gene expression in vivo. In our method, when applied, morpholino molecules are taken up by the cells lining the ventricular surface. These cells include the radial glial cells, which act as neurogenic progenitors. Therefore, knocking down gene expression in the radial glial cells is of utmost importance to analyze the widespread neurogenesis response in zebrafish, and also would provide insight into how vertebrates could sustain adult neurogenesis response. Such an understanding would also help the efforts for clinical applications in human neurodegenerative disorders and central nervous system regeneration. Thus, we present the cerebroventricular microinjection method as a quick and efficient way to alter gene expression and neurogenesis response in the adult zebrafish forebrain. We also provide troubleshooting tips and other useful information on how to carry out the CVMI procedure.

In this article, we demonstrate a method for manipulation of gene expression in the ventricular cells of the adult zebrafish telencephalon using antisense morpholino oligonucleotides. We present this method as an efficient and quick protocol that can be used for functional studies in the adult vertebrate brain.

Manipulation of gene expression in tissues is  required to perform functional studies. In this paper, we demonstrate the  cerebroventricular ...

Simultaneous Electrophysiological Recording and Calcium Imaging of Suprachiasmatic Nucleus Neurons

Simultaneous electrophysiological and fluorescent imaging recording methods were used to study the role of changes of membrane potential or current in regulating the intracellular calcium concentration. Changing environmental conditions, such as the light-dark cycle, can modify neuronal and neural network activity and the expression of a family of circadian clock genes within the suprachiasmatic nucleus (SCN), the location of the master circadian clock in the mammalian brain. Excitatory synaptic transmission leads to an increase in the postsynaptic Ca2+ concentration that is believed to activate the signaling pathways that shifts the rhythmic expression of circadian clock genes. Hypothalamic slices containing the SCN were patch clamped using microelectrodes filled with an internal solution containing the calcium indicator bis-fura-2. After a seal was formed between the microelectrode and the SCN neuronal membrane, the membrane was ruptured using gentle suction and the calcium probe diffused into the neuron filling both the soma and dendrites. Quantitative ratiometric measurements of the intracellular calcium concentration were recorded simultaneously with membrane potential or current. Using these methods it is possible to study the role of changes of the intracellular calcium concentration produced by synaptic activity and action potential firing of individual neurons. In this presentation we demonstrate the methods to simultaneously record electrophysiological activity along with intracellular calcium from individual SCN neurons maintained in brain slices.

Procedures are described to perform simultaneous recordings of membrane potential or current and changes of intracellular calcium concentration. Suprachiasmatic nucleus neurons are filled with the calcium indicator bis-fura-2 using a patch clamp electrode in the whole cell patch clamp configuration.

Simultaneous electrophysiological and fluorescent imaging recording methods were used to study the role of changes of membrane potential or current in ...

Analysis of Gene Expression Changes in the Rat Hippocampus After Deep Brain Stimulation of the Anterior Thalamic Nucleus

Deep brain stimulation (DBS) surgery, targeting various regions of the brain such as the basal ganglia, thalamus, and subthalamic regions, is an effective treatment for several movement disorders that have failed to respond to medication. Recent progress in the field of DBS surgery has begun to extend the application of this surgical technique to other conditions as diverse as morbid obesity, depression and obsessive compulsive disorder. Despite these expanding indications, little is known about the underlying physiological mechanisms that facilitate the beneficial effects of DBS surgery. One approach to this question is to perform gene expression analysis in neurons that receive the electrical stimulation. Previous studies have shown that neurogenesis in the rat dentate gyrus is elicited in DBS targeting of the anterior nucleus of the thalamus1. DBS surgery targeting the ATN is used widely for treatment refractory epilepsy. It is thus of much interest for us to explore the transcriptional changes induced by electrically stimulating the ATN. In this manuscript, we describe our methodologies for stereotactically-guided DBS surgery targeting the ATN in adult male Wistar rats. We also discuss the subsequent steps for tissue dissection, RNA isolation, cDNA preparation and quantitative RT-PCR for measuring gene expression changes. This method could be applied and modified for stimulating the basal ganglia and other regions of the brain commonly clinically targeted. The gene expression study described here assumes a candidate target gene approach for discovering molecular players that could be directing the mechanism for DBS.

The mechanism underlying the therapeutic effects of Deep Brain Stimulation (DBS) surgery needs investigation. The methods presented in this manuscript describe an experimental approach to examine the cellular events triggered by DBS by analyzing the gene expression profile of candidate genes that can facilitate neurogenesis post DBS surgery.

Deep brain stimulation (DBS) surgery, targeting various regions of the brain such as the basal ganglia, thalamus, and subthalamic regions, is an effective ...