First published online 21 July 2004
doi: 10.1242/dev.01240
Development 131, 4085-4093 (2004)
Published by The Company of Biologists 2004
A genetic screen in zebrafish identifies cilia genes as a principal cause of cystic kidney
Zhaoxia Sun1,*,
Adam Amsterdam1,
Gregory J. Pazour2,
Douglas G. Cole3,
Mark S. Miller3 and
Nancy Hopkins1,
1 MIT, Center for Cancer Research and Biology Department, Building E17 Room 340,
77 Massachusetts Avenue, Cambridge, MA 02139, USA
2 Program in Molecular Medicine, University of Massachusetts Medical School, 373
Plantation Street, Worcester, MA 01605, USA
3 Department of Microbiology, Molecular Biology and Biochemistry (LSS142),
University of Idaho, Moscow, ID 83844, USA
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Fig. 1. Phenotypes of identified mutants. (A) A larryhi409
mutant on day 5 shows kidney cyst (arrow) and body curvature. (B,C)
Cross-section of the glomerular (arrow)-tubular (arrowhead) region of
wild-type (B) and larryhi409 (C) embryos at 50 hpf (hour
post fertilization). (D) pkd2 morphant at 53 hpf shows kidney cyst
(arrow) and body curvature. nc, notochord; wt, wild type; mut, mutant;
control, embryo injected with standard control morpholino oligo; mph,
morphant.
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Fig. 2. mRNA is affected in mutant embryos. (A) RT-PCR on cDNA from mutant and
wild-type hi3308 embryos with a pair of hi3308/seahorse
specific primers flanking the insertion site. (B) Control RT-PCR with a pair
of actin specific primers. A serial dilution of cDNA was used to show that
similar amounts of cDNA were used. m, 1 kb ladder; wt, wild type; mu, mutant;
1-4, 1:10, 1:200, 1:4,000 and 1:80,000 dilutions.
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Fig. 3. hi409/IFT81 is widely expressed. (A) In situ hybridization for
hi409/IFT81 in an embryo at the eight-somite stage (8S),
hi409/IFT81 is enriched in the notochord (arrow). (B) In embryos at
25 hpf, hi409/IFT81 is enriched in the brain ventricle (arrow). (C)
In embryos at 34 hpf, hi409/IFT81 is enriched in the otic vesicle
(arrow) and slightly in the pronephric duct (arrowhead).
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Fig. 4. Ciliary defects in scorpionhi459. (A) The pronephric
duct region (arrow) in a wild-type embryo at 50 hpf reacts strongly with an
antibody against acetylated tubulin. (B) Confocal image shows cilia stained
with this antibody in the pronephric duct of a wild-type embryo at 24 hpf. (D)
Defect of the cilia in scorpionhi459 at 50 hpf; (D)
enlarged view of C. wt, wild type; 459, scorpionhi459.
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Fig. 5. Pronephric ducts. (A,B) Cross-section through pronephric ducts (arrow on
the right side; encircled on the left) in wild-type (wt) and
larryhi409 mutant (409) embryos. (C,D) Dorsal view of the
pronephric ducts stained with  6F. nc, notochord.
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Fig. 6. A model shows the formation of cilia during the development of epithelial
tubes. During epithelium differentiation, the cilium forms. The formation of
the cilia requires hi459/scorpion and IFT components. The cilium protrudes
into the lumen from the apical surface of epithelial cells and serves as an
antenna of the cell. Mechanosensory channels (polycystins, etc.) on the cilium
could be activated by liquid flow, interaction with neighboring cells or
chemicals/ligands in the lumen. A resultant Ca2+ influx triggers a
signaling cascade that regulates cell proliferation and/or size. Defects in
cilia formation or function lead to uncontrolled proliferation of epithelial
cells and eventually cyst formation in local areas.
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© The Company of Biologists Ltd 2004
