Ectopic expression is one technique to elucidate the microRNAs role in brain development. However, targeting specific areas using in ovo electroporation is challenging. Here, we show an efficient way to selectively electroporate ventral and dorsal midbrain regions.
Non-coding RNAs are additional players in regulating gene expression. Targeted in ovo electroporation of specific areas provides a unique tool for spatial and temporal control of ectopic microRNA expression. However, ventral brain structures like ventral midbrain are rather difficult to reach for any manipulations. Here, we demonstrate an efficient way to electroporate miRNA into ventral midbrain using thin platinum electrodes. This method offers a reliable way to transfect specific areas of the midbrain and a useful tool for in vivo studies.
The recognition of small non-coding RNAs as additional players for gene expression launched a new complexity to genomic programming/gene regulation. Different species of non-coding RNAs have functional importance in neural cells, including small non-coding RNAs1-4. MicroRNAs (miR or miRNA) for example show distinct and changing expression profiles in developing brains5. Targeted in ovo electroporation of chick embryos provides a unique opportunity for temporal and spatial control of gene expression and silencing during development.
This video demonstrates the different steps of performing ectopic expression of miRs in specific areas of the chick midbrain using in ovo electroporation6-10. To ensure a long lasting effect of these small non-coding RNAs in cells, the DNA sequence of miRs were cloned into mono- or bi-cistronic vectors. For in ovo electroporation, miR containing vector is injected into the midbrain neural tube by exposing the embryo after making a small window in the egg shell. To transfect specific areas of the midbrain small plus (anode) and minus (cathode) platinum electrodes are placed at specific positions. For ventral midbrain transfection, the anode is placed underneath the left ventral midbrain and the cathode above the right half of the midbrain before applying a current. The opening in the eggshell is closed with tape and embryos are incubated for as long as required for any analysis. This method was originally described by Muramatsu et al.6 and improved by Momose et al.8 for specific area transfection.
Schematic Overview.
This video demonstrates an effective method to transfect plasmid into the neuroepithelial cells of specific areas of the chick midbrain. Rectangular electric pulses of low voltage can introduce DNA into cells of the chick neural tube in ovo6,16. However, the accuracy of DNA targeting is often hindered by the wide electric field, which rises through the relatively large electrodes (Φ = 0.5 mm). We tried to tackle that problem by using electrodes smaller in diameter following the guidelines of Momos…
The authors have nothing to disclose.
We acknowledge K. Mikic, who contributed to the initial phase of this movie and M. Nicolescu for the miR picture. C. Huber was supported by a fellowship of the IZKF of the Universtitätsklinikum Tübingen, A. Alwin Prem Anand by the Fortüne programme of the Universtitätsklinikum Tübingen.
Name | Company | Model | |
Borosillicate glass capillaries | Hartenstein | Model: 0.9 mm | |
Microcapillary puller | WPI, Berlin | Model: Pul1-E | |
Electroporator | Intracel | Model: TSSIC | |
Stereomicroscope – fluorescence | LEICA | Model: MZFLIII | |
Stereomicroscope | Zeiss | Model: Stemi | |
Camera and software | Zeiss | Model: Axiocam MRc/ Axiovision Re. 4.8 |