We thank Prof. Christoph Englert and Prof. Didier Stainier for gifting the Tg(wt1b:GFP) li1 and Tg(kdrl:EGFP)s843 strains, respectively, and the Taiwan Zebrafish Core Facility for providing Tg(kdrl:mCherry)ci5. This study was supported by grants from Taiwan&#39;s Ministry of Science and Technology (96-2628-B-029-002-MY3, 101-2313-B-029-001, 102-2628-B-029-002-MY3, 102-2321-B-400-018).

Ethics Statement: All experimental procedures on zebrafish were approved by the Institutional Animal Care and Use Committee of Tunghai University (IRB Approval NO. 101-12) and carried out in accordance with the approved guidelines.
1. Stock Solutions for 3&#946;-Hsd Enzymatic Activity Staining
<ol>
	<li>Prepare trans-dehydroandrosterone [10 mg/ml in dimethyl sulfoxide (DMSO)].</li>
	<li>Prepare &#946;-nicotinamide adenine dinucleotide hydrate (1.2 mg/ml in 0.1 M phosphate buffer, pH 7.2).</l...

<ol>
	<li>Hsu, H. J., Lin, G., Chung, 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=Parallel+early+development+of+zebrafish+interrenal+glands+and+pronephros:+differential+control+by+wt1+and+ff1b.">Parallel early development of zebrafish interrenal glands and pronephros: differential control by wt1 and ff1b.</a> Development. 130, 2107-2116 (2003).</li><li>To, T. T., 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=Pituitary-interrenal+interaction+in+zebrafish+interrenal+organ+development.">Pituitary-interrenal interaction in zebrafish interrenal organ development.</a> Mol Endocrinol. 21, 472-485 (2007).</li><li>Liu, Y. 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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=A+new+inherited+variant+of+the+3+beta-hydroxysteroid+dehydrogenase-isomerase+deficiency+syndrome:+evidence+for+the+existence+of+two+isoenzymes.">A new inherited variant of the 3 beta-hydroxysteroid dehydrogenase-isomerase deficiency syndrome: evidence for the existence of two isoenzymes.</a> J Clin Endocrinol Metab. 63, 360-367 (1986).</li><li>Lachance, 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=Characterization+of+human+3+beta-hydroxysteroid+dehydrogenase/delta+5-delta+4-isomerase+gene+and+its+expression+in+mammalian+cells.">Characterization of human 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase gene and its expression in mammalian cells.</a> J Biol Chem. 267, 3551 (1992).</li><li>Simard, 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=Molecular+biology+of+the+3beta-hydroxysteroid+dehydrogenase/delta5-delta4+isomerase+gene+family.">Molecular biology of the 3beta-hydroxysteroid dehydrogenase/delta5-delta4 isomerase gene family.</a> Endocr Rev. 26, 525-582 (2005).</li><li>Lin, J. 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=Two+zebrafish+hsd3b+genes+are+distinct+in+function,+expression,+and+evolution.">Two zebrafish hsd3b genes are distinct in function, expression, and evolution.</a> Endocrinology. 156, 2854-2862 (2015).</li><li>Grassi Milano, E., Basari, F., Chimenti, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adrenocortical+and+adrenomedullary+homologs+in+eight+species+of+adult+and+developing+teleosts:+morphology,+histology,+and+immunohistochemistry.">Adrenocortical and adrenomedullary homologs in eight species of adult and developing teleosts: morphology, histology, and immunohistochemistry.</a> Gen Comp Endocrinol. 108, 483-496 (1997).</li><li>Chai, C., Liu, Y. W., Chan, W. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ff1b+is+required+for+the+development+of+steroidogenic+component+of+the+zebrafish+interrenal+organ.">Ff1b is required for the development of steroidogenic component of the zebrafish interrenal organ.</a> Dev Biol. 260, 226-244 (2003).</li><li>Liu, Y. W., Gao, W., Teh, H. L., Tan, J. H., Chan, W. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prox1+is+a+novel+coregulator+of+Ff1b+and+is+involved+in+the+embryonic+development+of+the+zebra+fish+interrenal+primordium.">Prox1 is a novel coregulator of Ff1b and is involved in the embryonic development of the zebra fish interrenal primordium.</a> Mol Cell Biol. 23, 7243-7255 (2003).</li><li>Chai, C., Liu, Y. W., Chan, W. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ff1b+is+required+for+the+development+of+steroidogenic+component+of+the+zebrafish+interrenal+organ.">Ff1b is required for the development of steroidogenic component of the zebrafish interrenal organ.</a> Dev. Biol. 260, 226-244 (2003).</li><li>Chou, C. W., Zhuo, Y. L., Jiang, Z. Y., Liu, Y. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+hemodynamically-regulated+vascular+microenvironment+promotes+migration+of+the+steroidogenic+tissue+during+its+interaction+with+chromaffin+cells+in+the+zebrafish+embryo.">The hemodynamically-regulated vascular microenvironment promotes migration of the steroidogenic tissue during its interaction with chromaffin cells in the zebrafish embryo.</a> PLoS One. 9, e107997 (2014).</li><li>Liu, Y. W., Guo, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endothelium+is+required+for+the+promotion+of+interrenal+morphogenetic+movement+during+early+zebrafish+development.">Endothelium is required for the promotion of interrenal morphogenetic movement during early zebrafish development.</a> Dev Biol. 297, 44-58 (2006).</li><li>Jin, S. W., Beis, D., Mitchell, T., Chen, J. N., Stainier, D. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+and+molecular+analyses+of+vascular+tube+and+lumen+formation+in+zebrafish.">Cellular and molecular analyses of vascular tube and lumen formation in zebrafish.</a> Development. 132, 5199-5209 (2005).</li><li>Proulx, K., Lu, A., Sumanas, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cranial+vasculature+in+zebrafish+forms+by+angioblast+cluster-derived+angiogenesis.">Cranial vasculature in zebrafish forms by angioblast cluster-derived angiogenesis.</a> Dev Biol. 348, 34-46 (2010).</li><li>Perner, B., Englert, C., Bollig, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Wilms+tumor+genes+wt1a+and+wt1b+control+different+steps+during+formation+of+the+zebrafish+pronephros.">The Wilms tumor genes wt1a and wt1b control different steps during formation of the zebrafish pronephros.</a> Dev Biol. 309, 87-96 (2007).</li><li>Chou, C. W., Chiu, C. H., Liu, Y. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fibronectin+mediates+correct+positioning+of+the+interrenal+organ+in+zebrafish.">Fibronectin mediates correct positioning of the interrenal organ in zebrafish.</a> Dev Dyn. 242, 432-443 (2013).</li><li>Chiu, C. H., Chou, C. W., Takada, S., Liu, Y. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+and+fibronectin+signaling+requirements+of+the+zebrafish+interrenal+vessel.">Development and fibronectin signaling requirements of the zebrafish interrenal vessel.</a> PLoS One. 7, e43040 (2012).</li></ol>

The authors have no competing financial interests to declare.

The signal strength of the 3&#946;-Hsd activity increased over the course of reaction. Clear signals of the 3&#946;-Hsd activity were detected after 4 hours of reaction for stages from 28 hpf onward. However, the reaction duration requires empirical determination, depending on the purpose of the assay. In cases where the staining requires overnight processing, a slightly bluish background tends to develop on the samples. This problem can be overcome by increasing the fixation duration (e.g., 4 hr in 4% PFAT at R...

The adrenal gland, a crucial component of the hypothalamo-pituitary-adrenal axis, secretes steroids and coordinates steroid homeostasis and the bodily response to stress. The adrenal gland comprises the outer cortex, which secretes steroids in a zone-specific manner, and inner medulla, which synthesizes catecholamines. The interrenal gland in teleosts is the counterpart of the adrenal gland in mammals and is composed of steroidogenic interrenal and chromaffin cells, which are functional equivalents of the adrenal cortex and medulla, respectively1-3. Studies conducted using the zebrafish model have reported that both steroidogenic and chromaffin cell lineages are formed by molecular and cellular mechanisms highly resembling those in mammals1,2. Therefore, the zebrafish is a potentially powerful model for studying genetic disorders, neuroendocrine control, and systems biology of the hypothalamo-pituitary-adrenal (interrenal) axis.
In the adrenal gland, 3&#946;-Hsd catalyzes the conversion of progesterone from pregnenolone, 17&#945;-hydroxyprogesterone from 17&#945;-hydroxypregnelolone, and androstenedione from dehydroepiandrosterone4,5. 3&#946;-Hsd is essential for biosynthesizing all classes of hormonal steroids, namely progesterone, glucocorticoids, mineralocorticoids, androgens, and estrogens. The two human 3&#946;-Hsd isozymes HSD3B1 and HSD3B2 are differentially expressed6. HSD3B1 is expressed in the placenta and peripheral tissues, whereas HSD3B2 is expressed in the adrenal cortex and gonads. Human HSD3B1 and HSD3B2 are co-orthologs of zebrafish hsd3b1, which is expressed at the interrenal tissue and adult gonads; zebrafish hsd3b2 is a maternally expressed gene whose transcripts disappear before organogenesis7. The protocol of the whole-mount 3&#946;-Hsd enzymatic activity assay for zebrafish was developed by modifying Levy&#39;s method, as described by Milano et al., on frozen sections of eight teleost species8. Because of the tissue permeability and optical transparency of the developing zebrafish, whole-mount 3&#946;-Hsd histochemistry can be successfully used for the fixed zebrafish embryo and larvae and specifically delineate the differentiated interrenal tissues.
This sensitive and rapid assay has been applied to various mutants and morphants demonstrating different types of interrenal dysmorphogenesis. The interrenal 3&#946;-Hsd activity is absent in the embryo where specification of the interrenal tissue is disrupted through a specific knockdown of the Ff1b transcription factor and is decreased as the interrenal differentiation is affected by a knockdown of the Ff1b coregulator Prox19,10. Notably, the 3&#946;-Hsd activity can be detected in mutants with severe early stage defects, such as one-eyed pinhead and squint, where the 3&#946;-Hsd histochemistry delineates how the interrenal cell migration is affected11. The differentiation of the interrenal tissue is not compromised even in the complete absence of blood and vasculature. Therefore, how endothelium-derived signals shape the developing interrenal organ can be determined12,13. Overall, this histochemical assay has been successfully used for studying specification, differentiation, and migration of steroidogenic cells in the zebrafish model. Therefore, it should be an efficient and a reliable tool for any genetic or chemical screens targeting adrenal and interrenal organ disorders.

<table border="0" cellpadding="0" cellspacing="0" width="565">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Confocal microscope</td>
			<td style="width:187px;">Carl Zeiss&#160;</td>
			<td style="width:72px;">LSM510&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DMSO</td>
			<td>Sigma</td>
			<td>D8418&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Glycerol</td>
			<td>USB</td>
			<td>US16374</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Hyclone Fetal Calf Serum&#160;</td>
			<td>GE Healthcare Life Sciences</td>
			<td>SH30073</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Nicotinamide</td>
			<td>Sigma</td>
			<td>N0636</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">&#946;-Nicotinamide adenine dinucleotide hydrate</td>
			<td>Sigma</td>
			<td>N1636</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">4-Nitro blue tetrazolium</td>
			<td>Promega</td>
			<td>S380C</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Nusieve GTG</td>
			<td>Lonza</td>
			<td>50081</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Paraformaldehyde</td>
			<td>Sigma</td>
			<td>P6148</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phenylthiourea</td>
			<td>Sigma&#160;</td>
			<td>P7629</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phosphate buffered saline</td>
			<td>Sigma</td>
			<td>P4417-100Tab</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PYREX Spot Plate</td>
			<td>Corning</td>
			<td>7220-85</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Reef Salt</td>
			<td>AZOO</td>
			<td>AZ28001</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">trans-Dehydroandrosterone</td>
			<td>Sigma</td>
			<td>D4000</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Triton X-100</td>
			<td>Sigma</td>
			<td>T8787</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tween 20</td>
			<td>Sigma</td>
			<td>P9416</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Vibratome</td>
			<td>Leica</td>
			<td>VT1000M</td>
		</tr>
	</tbody>
</table>

visualizing the interrenal steroidogenic tissue and its vascular microenvironment in zebrafish

This protocol introduces how to detect differentiated interrenal steroidogenic cells through a simple whole-mount enzymatic activity assay. Identifying differentiated steroidogenic tissues through chromogenic histochemical staining of 3-&#946;-Hydroxysteroid dehydrogenase /&#916;5-4 isomerase (3&#946;-Hsd) activity-positive cells is critical for monitoring the morphology and differentiation of adrenocortical and interrenal tissues in mammals and teleosts, respectively. In the zebrafish model, the optical transparency and tissue permeability of the developing embryos and larvae allow for whole-mount staining of 3&#946;-Hsd activity. This staining protocol, as performed on transgenic fluorescent reporter lines marking the developing pronephric and endothelial cells, enables the detection of the steroidogenic interrenal tissue in addition to the kidney and neighboring vasculature. In combination with vibratome sectioning, immunohistochemistry, and confocal microscopy, we can visualize and assay the vascular microenvironment of interrenal steroidogenic tissues. The 3&#946;-Hsd activity assay is essential for studying the cell biology of the zebrafish interrenal gland because to date, no suitable antibody is available for labeling zebrafish steroidogenic cells. Furthermore, this assay is rapid and simple, thus providing a powerful tool for mutant screens targeting adrenal (interrenal) genetic disorders as well as for determining disruption effects of chemicals on steroidogenesis in pharmaceutical or toxicological studies.

To determine how the steroidogenic interrenal tissue codevelops with the pronephric kidney glomerulus and its nascent vasculature, the 3&#946;-Hsd enzymatic activity assay was performed on the double transgenic Tg(wt1b:GFP)li1;Tg(kdrl:mCherry)ci5 embryo at 34 hpf (Figure 1). At this stage, the 3&#946;-Hsd activity-positive steroidogenic tissue is located right to the midline and immediately caudal to the pronephric kidney glomerulus, whereas...

Watch this Scientific Journal Video about Visualizing the Interrenal Steroidogenic Tissue and Its Vascular Microenvironment in Zebrafish at JoVE.com

Visualizing the Interrenal Steroidogenic Tissue and Its Vascular Microenvironment in Zebrafish

The interrenal gland in zebrafish is the teleostean counterpart of the mammalian adrenal gland. This protocol introduces how to perform the 3-&#946;-hydroxysteroid dehydrogenase (&#916;5-4 isomerase; 3&#946;-Hsd) enzymatic activity assay, which detects differentiated steroidogenic cells in the developing zebrafish.

This protocol introduces how to detect differentiated interrenal steroidogenic cells through a simple whole-mount enzymatic activity assay. Identifying ...

The overall goal of this procedure is to detect differentiated interrenal steroidogenic cells in the developing zebrafish through a simple whole-mount enzymatic activity assay. This staining procedure can help answer key questions regarding the molecular and cellular mechanisms of interrenal gland formation and malformation. The main advantage of this staining assay is that it's rapid, simple, and reliable, making it a powerful tool for genetic or chemical screens in zebrafish.This procedure can be performed on trangenic fluorescent reporter lines, marking the kidney and the blood vessels so that multiple tissues in the same embryo can be analyzed. In combination with vibratome sectioning, immunohistochemistry, and confocal microscopy, the vascular microenvironment of the interrenal tissue can also be visualized. After preparing stock solutions for three beta-Hsd activity staining according to the text protocol, place developing zebrafish embryos in 0.03%PTU in egg water to inhibit pigment formation.Fix dechorionated embryos, or larvae, in 2%or 4%PFA in PBS with 0.1%Tween 20, or PFAT. With PBST, wash the embryos four times for 10 minutes each, ensuring that the samples do not dry out between washes. Prior to the staining reactions, freshly prepare parts A and B in separate tubes, then vortex and centrifuge the solutions.It is essential to prepare parts A and B in separate tubes. Adding all the components straight into one single tube will cause severe precipitation right away. Add the entire tube of part A to the entire tube of part B.Mix well, and immediately distribute one milliliter into each microfuge tube containing fixed and washed embryos.Use aluminum foil to wrap the tubes, and place them at room temperature on a rotator or a rocking platform with gentle shaking. Empirically determine the reaction time by using a microscope to monitor chromogenic signals. Slight precipitations will develop over time that will not interfere with the reaction process.Stop the reaction by using PBST to wash the embryos four times for 10 minutes each, then post-fix the stained embryos with 4%PFAT at room temperature for 60 minutes. For whole-mount microscopy, use 50%glycerol in PBS to clear the embryos. Then, after orienting them with the dorsal side facing up, observe the samples using an upright microscope under bright field illumination.De-yolk the embryo, and use it to prepare a flat mount. Then, capture a high-resolution image of the interrenal tissue morphology. To analyze the vascular microenvironment of the steroidogenic tissue, post-fix the stained embryos with 2%PFA.Supplement it with 1%Triton X-100 at four degrees Celsius for one hour, and use PBST-X to wash the embryos at room temperature four times for 10 minutes each. To embed the embryos, prepare 4%low-melting agarose by dissolving agarose in PBS at 95 degrees Celsius. Then, aliquot in microcentrifuge tubes, and store at four to eight degrees Celsius.Melt an aliquot of 4%low-melting agarose at 70 degrees Celsius for 10 minutes, then keep the aliquot at 47 degrees Celsius. Using a detached cap from a 1.5%milliliter microcentrifuge tube as a mold, embed an embryo in molten agarose, and allow it to cool until solid. To carry out vibratome sectioning, adhere a piece of paper tape to the dry platform of the vibratome.Then, use a razor blade to remove the hardened agarose block from the mold. Apply superglue to the paper tape on the platform, and fix the agarose block onto the paper tape with the anterior side of the sample facing up. Next, trim the agarose block to a trapezoidal prism shape with approximately four to eight millimeters on each side of the upper and lower facets respectively.Use a dropper filled with cold PBS with 0.5%Trident X-100 to rinse the agarose block. Then, use a vibratome according to the manufacturer's instructions to prepare 100 micrometer sections. With a 26-gauge needle, remove cut sections from the vibratome and transfer them to a spot plate containing 500 microliters of cold 0.5%PBST-X per well.Collect the three beta-Hsd activity positive tissue sections by checking under a dissection microscope, and use a pipette tip to transfer the sections into a 96-well plate containing cold 0.5%PBST-X. Further stain and image the sections according to the text protocol. To determine how steroidogenic interrenal tissue codevelops with the pronephric kidney glomerulus and its nascent vasculature, the three beta-Hsd enzymatic activity assay was performed on a double transgenic zebrafish embryo, expressing both kidney-specific and endothelial-specific fluorescence.As shown here, three beta-Hsd positive steroidogenic tissue is located right of the midline and immediately coddle to the pronephric kidney glomerulus. Some steroidogenic cells also start migrating across the midline. These vibratome sections from transgenic embryos expressing endothelial GFP subjected to the three beta-Hsd assay were analyzed by immunohistochemistry to detect fibronectin and its downstream effector, phosphorylated focal adhesion kinase.The peri-dorsal aorta deposition of fibronectin is essential for supporting interrenal vessel growth. For the fish embryo or larva, the whole-mount histochemical staining can be done within one day if it is performed properly. Although this staining method is simple and rapid, it is important to remember that it is detecting only one single enzyme of the steroidogenic pathway.If aiming for a developmental analysis of the interrenal tissue, in addition to this assay, in situ habitization will have to be performed to detect the expression of other critical genes involved in steroidogenesis.

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Developmental Biology

6.8K Görüntüleme.  Tunghai University. The overall goal of this procedure is to detect differentiated interrenal steroidogenic cells in the developing zebrafish through a simple whole-mount enzymatic activity assay. This staining procedure can help answer key questions regarding the molecular and cellular mechanisms of interrenal gland formation and malformation. The main advantage of this staining assay is that it's rapid, simple, and reliable, making it a powerful tool for genetic or chemical screens in zebrafish.This pro...