Start-up monies to A. Dickinson from VCU supported this work.
The authors wish to acknowledge Dan Nacu for his artistic talent in creating the schematic illustration.

<ol>
	<li>Mossey, P. A., Little, J., Munger, R. G., Dixon, M. J., Shaw, W. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cleft+lip+and+palate.">Cleft lip and palate.</a> Lancet. 374, 1773-1785 (2009).</li><li>Kennedy, A. E., Dickinson, 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=Median+facial+clefts+in+Xenopus+laevis:+roles+of+retinoic+acid+signaling+and+homeobox+genes.">Median facial clefts in Xenopus laevis: roles of retinoic acid signaling and homeobox genes.</a> Dev Biol. 365, 229-240 (2012).</li><li>Kennedy, A. E., Dickinson, 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=Quantitative+Analysis+of+Orofacial+Development+and+Median+Clefts+in+Xenopus+Laevis.">Quantitative Analysis of Orofacial Development and Median Clefts in Xenopus Laevis.</a> Anat Rec (Hoboken). , (2014).</li><li>Dickinson, A., Sive, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Positioning+the+extreme+anterior+in+Xenopus:+cement+gland,+primary+mouth+and+anterior+pituitary.">Positioning the extreme anterior in Xenopus: cement gland, primary mouth and anterior pituitary.</a> Semin Cell Dev Biol. 18, 525-533 (2007).</li><li>Dickinson, A. J., Sive, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+the+primary+mouth+in+Xenopus+laevis.">Development of the primary mouth in Xenopus laevis.</a> Dev Biol. 295, 700-713 (2006).</li><li>Dickinson, A. J., Sive, H. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Wnt+antagonists+Frzb-1+and+Crescent+locally+regulate+basement+membrane+dissolution+in+the+developing+primary+mouth.">The Wnt antagonists Frzb-1 and Crescent locally regulate basement membrane dissolution in the developing primary mouth.</a> Development. 136, 1071-1081 (2009).</li><li>Barnett, 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=Syndrome+Transcription+Factor+is+critical+for+neural+crest+cell+function+in+Xenopus+laevis.">Syndrome Transcription Factor is critical for neural crest cell function in Xenopus laevis.</a> Mech Dev. 129, 324-338 (2012).</li><li>Gonzales, B., Yang, H., Henning, D., Valdez, B. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cloning+and+functional+characterization+of+the+Xenopus+orthologue+of+the+Treacher+Collins+syndrome+(TCOF1)+gene+product.">Cloning and functional characterization of the Xenopus orthologue of the Treacher Collins syndrome (TCOF1) gene product.</a> Gene. 359, 73-80 (2005).</li><li>Reisoli, E., De Lucchini, S., Nardi, I., Ori, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serotonin+2B+receptor+signaling+is+required+for+craniofacial+morphogenesis+and+jaw+joint+formation+in+Xenopus.">Serotonin 2B receptor signaling is required for craniofacial morphogenesis and jaw joint formation in Xenopus.</a> Development. 137, 2927-2937 (2010).</li><li>Schuff, 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=FoxN3+is+required+for+craniofacial+and+eye+development+of+Xenopus+laevis.">FoxN3 is required for craniofacial and eye development of Xenopus laevis.</a> Dev Dyn. 236, 226-239 (2007).</li><li>Slater, B. J., Liu, K. J., Kwan, M. D., Quarto, N., Longaker, M. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cranial+osteogenesis+and+suture+morphology+in+Xenopus+laevis:+a+unique+model+system+for+studying+craniofacial+development.">Cranial osteogenesis and suture morphology in Xenopus laevis: a unique model system for studying craniofacial development.</a> PLoS One. 4, (2009).</li><li>Vandenberg, L. N., Adams, D. S., Levin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Normalized+shape+and+location+of+perturbed+craniofacial+structures+in+the+Xenopus+tadpole+reveal+an+innate+ability+to+achieve+correct+morphology.">Normalized shape and location of perturbed craniofacial structures in the Xenopus tadpole reveal an innate ability to achieve correct morphology.</a> Dev Dyn. 241, 863-878 (2012).</li><li>Bugaighis, I., Mattick, C. R., Tiddeman, B., Hobson, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3D+Facial+Morphometry+in+Children+with+Oral+Clefts.">3D Facial Morphometry in Children with Oral Clefts.</a> Cleft Palate Craniofac J. , (2013).</li><li>Farkas, L. G., Katic, M. J., Forrest, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+anatomy+of+the+face+in+Down's+syndrome:+anthropometric+proportion+indices+in+the+craniofacial+regions.">Surface anatomy of the face in Down's syndrome: anthropometric proportion indices in the craniofacial regions.</a> J Craniofac Surg. 12, 519-524 (2001).</li><li>Scheuer, H. A., Holtje, W. J., Hasund, A., Pfeifer, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prognosis+of+facial+growth+in+patients+with+unilateral+complete+clefts+of+the+lip,+alveolus+and+palate.">Prognosis of facial growth in patients with unilateral complete clefts of the lip, alveolus and palate.</a> J Craniomaxillofac Surg. 29, 198-204 (2001).</li><li>Parsons, K. J., Andreeva, V., James Cooper, W., Yelick, P. C., Craig Albertson, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphogenesis+of+the+zebrafish+jaw:+development+beyond+the+embryo.">Morphogenesis of the zebrafish jaw: development beyond the embryo.</a> Methods Cell Biol. 101, 225-248 (2011).</li><li>Farkas, L. G., Katic, M. J., Forrest, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+anatomy+of+the+face+in+Down's+syndrome:+age-related+changes+of+anthropometric+proportion+indices+in+the+craniofacial+regions.">Surface anatomy of the face in Down's syndrome: age-related changes of anthropometric proportion indices in the craniofacial regions.</a> J Craniofac Surg. 13, 368-374 (2002).</li><li>Cooper, W. J., 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=Bentho-pelagic+divergence+of+cichlid+feeding+architecture+was+prodigious+and+consistent+during+multiple+adaptive+radiations+within+African+rift-lakes.">Bentho-pelagic divergence of cichlid feeding architecture was prodigious and consistent during multiple adaptive radiations within African rift-lakes.</a> PLoS One. 5, (2010).</li><li>Klingenberg, C. P., 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=Prenatal+alcohol+exposure+alters+the+patterns+of+facial+asymmetry.">Prenatal alcohol exposure alters the patterns of facial asymmetry.</a> Alcohol. 44, 649-657 (2010).</li><li>Zhao, 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=Isolated+cleft+palate+in+mice+with+a+targeted+mutation+of+the+LIM+homeobox+gene+lhx8.">Isolated cleft palate in mice with a targeted mutation of the LIM homeobox gene lhx8.</a> Proc Natl Acad Sci U S A. 96, 15002-15006 (1999).</li><li>Allam, K. A., 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=The+spectrum+of+median+craniofacial+dysplasia.">The spectrum of median craniofacial dysplasia.</a> Plast Reconstr Surg. , 812-821 (2011).</li><li>Sive, H. L., Grainger, R., Harlard, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Early development of Xenopus laevis: a laboratory manual. , (2000).</li><li>Cross, M. K., Powers, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Obtaining+eggs+from+Xenopus+laevis+females.">Obtaining eggs from Xenopus laevis females.</a> J Vis Exp. , (2008).</li><li>Nieuwkoop, P. D., Faber, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Normal Table of Xenopus Laevis (Daudin). , (1967).</li><li>Nieuwkoop, P. D. a. F. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Normal Table of Xenopus laevis (Daudin): A Systematical and Chronological Survey of the Development from the Fertilized Egg till the End of Metamorphosis. , (1994).</li><li>Abdi, H., Williams, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Principal+Component+Analysis.">Principal Component Analysis.</a> WIREs Computational Statistics. 2, (2010).</li><li>Hill, T. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> P. STATISTICS: Methods and Applications. , (2013).</li></ol>

The authors have nothing to disclose.

Xenopus laevis has become a useful tool for dissecting the developmental mechanisms underlying orofacial development; however, there are currently no protocols describing size and shape changes of this region in frogs. The method described here will contribute significantly to the field of orofacial development by allowing for more rigorous quantification of orofacial phenotypes in Xenopus and other vertebrates.
The first, most critical aspect of properly executing this proto...

Among the most prevalent and devastating types of human birth defects are those affecting the mouth and face, such as orofacial clefts1. Children with malformed orofacial structures undergo multiple surgeries throughout their lifetime and struggle with facial disfigurements, speech, hearing and eating problems. Therefore, facilitating new research in cranio- and orofacial development is paramount to prevention and treatment of these types of birth defects in humans. Xenopus laevis has emerged as a new tool for dissecting the mechanisms governing craniofacial development (some examples include2,3,4-11). Therefore, a quantitative method to analyze size and shape changes during development of the head and face of this species could be very powerful 3.
Here, we present such a method; combining traditional size measurements with geometric morphometrics adapted from a Xenopus study12 and a wealth of studies analyzing human facial form13-15. The goal of this protocol is to allow researchers to quantify facial size and shapes to distinguish between different orofacial phenotypes during normal and abnormal development. This analysis will allow for better differentiation between subtle craniofacial defects such as those arising from synergistic effects of genes and/or environmental factors. Additionally, this quantification method could also reveal even slight improvement or rescue of an orofacial defect. This therefore makes it a useful guide in analyzing potential therapeutics.
The combination of facial measurements and geometric morphometrics that we present here allows for a more comprehensive statistical analysis of both size and shape of the orofacial region than current protocols which largely utilize only one or the other15-18. Further, we present a simple way to assess both the medial and lateral planes of the face without requiring sophisticated three-dimensional imaging equipment used in current studies13,19.
We demonstrate this protocol on Xenopus laevis embryos treated with a retinoic acid receptor inhibitor that induces abnormal orofacial development and a median cleft palate2,3. Quantification of the dimensions and shape of the orofacial region in these embryos has revealed changes in the midface that is analogous to humans with similar palatal clefts and mouse models 20,21. However, this protocol can be utilized to assess the effects of other compounds on orofacial development such as natural substances, herbicides, or proteins such as growth factors. Further, orofacial size and shape changes arising from perturbation of gene expression via loss or gain of function experiments (using antisense morpholinos or Crispers/Talens) can also be quantified using this protocol. Finally, we developed this method specifically to assess Xenopus morphology; however, it is easily modified for analysis of any vertebrate. Other applications could also include using this protocol for comparing closely related species for evolutionary or ecological studies. While the example we provide here utilizes this protocol to describe analysis of the orofacial region, it could easily be modified for analysis of other regions, organs, or structures.
This orofacial quantification protocol will become a valuable resource for the research community, as well as an excellent teaching tool for undergraduate students as a video demonstration.

<table border="0" cellpadding="0" cellspacing="0" width="818">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:304px;">Name of the reagent</td>
			<td style="width:143px;">Company</td>
			<td style="width:136px;">Catalogue number</td>
			<td style="width:236px;">Comments (optional)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dissecting microscope</td>
			<td>Zeiss</td>
			<td></td>
			<td>fitted with AxioCamICC1 camera</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dumont #5 Inox forceps</td>
			<td>Fine Science Tools</td>
			<td>11251-10</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sterile, disposable scalpel</td>
			<td>Sklar</td>
			<td>06-2015</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:304px;">24-well plate</td>
			<td style="width:143px;">Fisher Scientific</td>
			<td style="width:136px;">087721</td>
			<td style="width:236px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:304px;">Standard Disposable transfer pipettes</td>
			<td style="width:143px;">Fisher Scientific</td>
			<td style="width:136px;">13-711-7M</td>
			<td style="width:236px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:304px;">150 mm X 15 mm Petri dishes</td>
			<td style="width:143px;">Falcon</td>
			<td style="width:136px;">351058</td>
			<td style="width:236px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:304px;">Incubators</td>
			<td style="width:143px;">Ectotherm</td>
			<td style="width:136px;"></td>
			<td style="width:236px;">set to 15C or 20C&#160;</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:304px;">Modeling Clay</td>
			<td style="width:143px;">Premo, or other non-toxic modeling clay</td>
			<td style="width:136px;"></td>
			<td style="width:236px;">in black or white</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:304px;">Straight teasing needle</td>
			<td style="width:143px;">Thermo Scientific</td>
			<td style="width:136px;">19010</td>
			<td style="width:236px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:304px;">Capillary Tubing (for needles)</td>
			<td>FHC</td>
			<td>30-30-1</td>
			<td style="width:236px;">Borosil 1.0mm OD x 0.5mm ID/Fiber, 100 mm each</td>
		</tr>
		<tr height="80">
			<td height="80" style="height:80px;width:304px;">Needle Puller, Model P-97&#160;</td>
			<td style="width:143px;">Sutter Instrument Co,&#160;</td>
			<td style="width:136px;">Needle Puller: P-97 Flaming/ Bown micropipette puller Filament: FB300B</td>
			<td style="width:236px;">For filaments, use Sutter 3.00mm square box filaments, 3.0mm wide.</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:304px;">Pipettemen</td>
			<td style="width:143px;">Gilson</td>
			<td style="width:136px;">F144802, F123600, F123602</td>
			<td style="width:236px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:304px;">BMS-453</td>
			<td style="width:143px;">Tocris</td>
			<td style="width:136px;">3409</td>
			<td style="width:236px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:304px;">DMSO</td>
			<td style="width:143px;">American Bioanalytical</td>
			<td style="width:136px;">AB00435-01000</td>
			<td style="width:236px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:304px;">Cysteine</td>
			<td style="width:143px;">Sigma-Aldrich</td>
			<td style="width:136px;">52-90-4</td>
			<td style="width:236px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:304px;">Paraformaldehyde powder</td>
			<td style="width:143px;">Sigma-Aldrich</td>
			<td style="width:136px;">158127</td>
			<td style="width:236px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:304px;">Petri dishes</td>
			<td style="width:143px;">Falcom</td>
			<td style="width:136px;">353003, 351058</td>
			<td style="width:236px;">100 mm diameter and 150 mm in diameter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:304px;">100% Ethanol</td>
			<td style="width:143px;">VWR</td>
			<td>89125-170</td>
			<td style="width:236px;"></td>
		</tr>
	</tbody>
</table>

quantification of orofacial phenotypes in xenopus

Xenopus has become an important tool for dissecting the mechanisms governing craniofacial development and defects. A method to quantify orofacial development will allow for more rigorous analysis of orofacial phenotypes upon abrogation with substances that can genetically or molecularly manipulate gene expression or protein function. Using two dimensional images of the embryonic heads, traditional size dimensions-such as orofacial width, height and area- are measured. In addition, a roundness measure of the embryonic mouth opening is used to describe the shape of the mouth. Geometric morphometrics of these two dimensional images is also performed to provide a more sophisticated view of changes in the shape of the orofacial region. Landmarks are assigned to specific points in the orofacial region and coordinates are created. A principle component analysis is used to reduce landmark coordinates to principle components that then discriminate the treatment groups. These results are displayed as a scatter plot in which individuals with similar orofacial shapes cluster together. It is also useful to perform a discriminant function analysis, which statistically compares the positions of the landmarks between two treatment groups. This analysis is displayed on a transformation grid where changes in landmark position are viewed as vectors. A grid is superimposed on these vectors so that a warping pattern is displayed to show where significant landmark positions have changed. Shape changes in the discriminant function analysis are based on a statistical measure, and therefore can be evaluated by a p-value. This analysis is simple and accessible, requiring only a stereoscope and freeware software, and thus will be a valuable research and teaching resource.

Here, a quantitative analysis of orofacial size and shape was demonstrated to compare embryos treated with a retinoic acid receptor inhibitor (RAR inhibitor) to untreated controls. Embryos were treated with a 1 &#956;M concentration of this chemical inhibitor from stage 24 to 30 (26-35 hpf), washed out, and fixed at stage 42 (82 hpf). They were then processed and analyzed as described in the protocol. Results are original data, but consistent with observations in previous publications2,3. Control embryos were ...

Watch this Scientific Journal Video about Quantification of Orofacial Phenotypes in Xenopus at JoVE.com

Quantification of Orofacial Phenotypes in Xenopus

A method to quantify the orofacial size and shape of Xenopus laevis embryos has been developed. In this protocol, traditional size measurements are combined with geometric morphometrics to allow for more sophisticated analyses of orofacial development and defects.

Quantification of Orofacial Phenotypes in Xenopus

Xenopus has become an important tool for dissecting the mechanisms governing craniofacial development and defects. A method to quantify orofacial ...

quantification-of-orofacial-phenotypes-in-xenopus

Research

JoVE Journal

Biology

9.7K Views.  Virginia Commonwealth University. A method to quantify the orofacial size and shape of Xenopus laevis embryos has been developed. In this protocol, traditional size measurements are combined with geometric morphometrics to allow for more sophisticated analyses of orofacial development and defects.