BACKGROUNDRetinoic acid (RA) is a potent signaling molecule that plays pleiotropic roles in patterning, morphogenesis, and organogenesis during embryonic development. The synthesis from retinol (vitamin A) to retinoic acid requires two sequential oxidative steps. The first step involves the oxidation of retinol to retinal through the action of retinol dehydrogenases. Retinol dehydrogenases1l (RDH1l) is a novel zebrafish retinol dehydrogenase. Herein we investigated the role of zebrafish RDH1l in heart development and cardiac performance in detail.

METHODSRDH1l specific morpholino was used to reduce the function of RDH1l in zebrafish. The gene expressions were observed by using whole mount in situ hybridization. Heart rates were observed and recorded under the microscope from 24 to 72 hours post fertilization (hpf). The cardiac performance was analyzed by measuring ventricular shortening fraction (VSF).

RESULTSThe knock-down of RDH1l led to abnormal neural crest cells migration and reduced numbers of neural crest cells in RDH1l morphant embryos. The reduced numbers of cardiac neural crest cells also can be seen in RDH1l morphant embryos. Furthermore, the morpholino-mediated knock-down of RDH1l resulted in the abnormal heart loop. The left-right determining genes expression pattern was altered in RDH1l morphant embryos. The impaired cardiac performance was observed in RDH1l morphant embryos. Taken together, these data demonstrate that RDH1l is essential for the heart development and cardiac performance in zebrafish.

CONCLUSIONSRDH1l plays a important role in the neural crest cells development, and then ultimately affects the heart loop and cardiac performance. These results show for the first time that an enzyme involved in the retinol to retinaldehyde conversion participate in the heart development and cardiac performance in zebrafish.

Alcohol Oxidoreductases ; genetics ; metabolism ; Animals ; Animals, Genetically Modified ; Heart ; embryology ; Zebrafish ; Zebrafish Proteins ; genetics ; metabolism

OBJECTIVETo perform the genetic identification of cloche(172) mutant zebrafish.

METHODSThe chemical mutagen N-ethyl-N-nitrosourea (ENU) was used to treat the AB stain male fish. Large-scale forward genetic screening was carried out to search for lyC-deficient zebrafish mutant by WISH. The morphology changes of the embryos at 3 days postfertilization (3dpf) stage were observed and the cloche(172) gene was identified by mapping and complementation test.

RESULTSWe selected 4 lyC-deficient zebrafish by WISH. cloche(172) mutant showed morphological changes similar to cloche mutant in 3dpf stage. One fourth of the embryos showed cloche phenotype as found in complementation test, and the cloche(172) gene was mapped on the telomere of zebrafish 13 chromosome where cloche gene was located. Numerous red blood cells were observed in the cloche(172) mutant, while only a few cells were found in the cloche mutant in the tail region by o-dianisdine staining.

CONCLUSIONcloche(172) gene which is responsible for the phenotype of cloche mutant may be a novel point mutation allele of the cloche mutant.

Alleles ; Animals ; Chromosome Mapping ; Cloning, Molecular ; Embryo, Nonmammalian ; embryology ; metabolism ; Ethylnitrosourea ; toxicity ; Genetic Complementation Test ; Male ; Muramidase ; genetics ; Mutation ; Zebrafish ; embryology ; genetics ; Zebrafish Proteins ; genetics

The effect of BHC80 (a component of BRAF-HDAC complex) on development was not well studied, because BHC80 gene knock-out mice died in one day after birth. Interestingly, zebrafish embryos can live, even if their important organs like cardiac system has severe dysfunction, as 25%-40% O2 are supplied through their skin. Therefore, a model of BHC80 gene knock-down zebrafish embryos was established to explore the effect of BHC80 on the early embryonic development. BHC80-morpholino antisense oligonucleotides 2 (BHC80-MO2) was designed and injected into zebrafish embryos to interrupt the correct translation of BHC80 mRNA at one or two cells stage, which was proved by RT-PCR analysis. Two control groups, including non-injection group and control-MO (con-MO) injection group, and four different doses of BHC80-MO2 injection groups, including 4 ng, 6 ng, 8 ng and 10 ng per embryo were set up. The embryonic heart phenotype and cardiac function were monitored, analyzed and compared between con-MO and BHC80-MO2 groups by fluorescence microscope in vmhc:gfp transgenic zebrafish which express green fluorescent protein in ventricle. The results showed that BHC80-MO2 microinjection effectively knocked down the BHC80 gene expression, because the BHC80-MO2 group emerged a new 249 bp band which reduced 51 bp compared to 300 bp band of con-MO group in RT-PCR analysis, and the 51 bp was the extron 10. The abnormal embryo rate rose with the increase of BHC80-MO2 dosage. The proper BHC80-MO2 injection dosage was 8 ng per embryo, as minor embryos had abnormal phenotype in 4 ng and 6 ng per embryo groups and most embryos died in 10 ng per embryo group. BHC80-MO2 embryos exhibited abnormal cardiac phenotype, including imbalance of the proportion of heart ventricle to atrium, incomplete D-loop, even tubular heart, slow heart rates and cardiac dysfunction. The results from a model of BHC80 gene knock-down zebrafish embryos show that the abnormal cardiac phenotype and cardiac dysfunction of BHC80-MO2 embryos may be one of the probable reasons for the BHC80 gene knock-out mice death, which would provide a good research model to clarify the mechanism of cardiac development.
Animals ; Embryonic Development ; genetics ; Gene Expression Regulation, Developmental ; Gene Knockdown Techniques ; Heart ; embryology ; Histone Deacetylases ; genetics ; Mice, Knockout ; Oligonucleotides, Antisense ; RNA, Messenger ; Zebrafish ; embryology ; Zebrafish Proteins ; genetics

OBJECTIVETo study the expression pattern of cd99l2 gene during zebrafish development, the RNA probes for whole-mount in situ hybridization were prepared in this study.

METHODSThe cd99l2 fragment obtained by RT-PCR was cloned into pGM-T Easy, then the plasmids were linearized with the restriction enzymes SacII or SalI. Using Sp6 or T(7) RNA polymerase, the digoxingenin-labeled antisense and sense probes were synthesized and confirmed by whole-mount in situ hybridization.

RESULTSThe plasmid cd99l2/pGM-T was constructed. cd99l2 gene expression pattern during embryogenesis of zebrafish was examined using the antisense probe, and intense expression was detected in the central nervous system during zebrafish development.

CONCLUSIONThe antisense probe can be used for study of the spatial and temporal distribution of cd99l2 during zebrafish development using the sense probe as control.

Animals ; Central Nervous System ; embryology ; Cloning, Molecular ; Digoxigenin ; chemistry ; Gene Expression Regulation, Developmental ; Oligonucleotide Probes ; RNA Probes ; Uridine Triphosphate ; chemistry ; Zebrafish ; embryology ; genetics ; Zebrafish Proteins ; genetics

Animals ; Keratolytic Agents ; pharmacology ; Neural Crest ; embryology ; metabolism ; Signal Transduction ; drug effects ; Tretinoin ; pharmacology ; Zebrafish ; Zebrafish Proteins ; genetics ; metabolism

OBJECTIVETo investigate the expression pattern of hoxd3 gene during early embryogenesis and angiogenesis of wild-type zebrafish.

METHODSTotal RNA was extracted from embryos of zebrafish in different development stages by trizol. The cDNA of hoxd3 gene was amplified by RT-PCR. The RT-PCR product was ligated to pCS(2+) vector by T4 DNA ligatase polymerase and sequenced. T3 RNA polymerase in vitro transcription system was used to obtain the probe of digoxin-labeled anti-sense mRNA of hoxd3 gene. The expression pattern of hoxd3 was detected by whole embryo in situ hybridization (WISH) with anti-sense mRNA probe.

RESULTSpCS(2+)-hoxd3 plasmid was successfully constructed, which was used to prepare anti-sense mRNA probe of hoxd3 in vitro. Expression pattern of hoxd3 gene was detected by WISH during zebrafish early embryogenesis and angiogenesis. It was observed that hoxd3 mRNA was expressed at the junction region of midbrain and hindbrain in wild-type zebrafish in embryos at 24 ≊72h postfertilization(hpf).

CONCLUSIONhoxd3 gene is mainly expressed in nervous system of wide-type zebrafish embryos.

Animals ; Cloning, Molecular ; Gene Expression Regulation, Developmental ; Genetic Vectors ; Homeodomain Proteins ; genetics ; metabolism ; In Situ Hybridization ; Plasmids ; genetics ; RNA, Messenger ; genetics ; Transfection ; Zebrafish ; embryology ; genetics ; Zebrafish Proteins ; genetics ; metabolism

OBJECTIVEDiGeorge/del22q11 syndrome is one of the most common genetic causes of outflow tract and aortic arch defects in human. DiGeorge/del22q11 is thought to involve an embryonic defect restricted to the pharyngeal arches and the corresponding pharyngeal pouches. Previous studies have evidenced that retinoic acid (RA) signaling is definitely indispensable for the development of the pharyngeal arches. Tbx1, one of the T-box containing genes, is proved to be the most attractive candidate gene for DiGeorge/del22q11 syndrome. However, the interaction between RA and Tbx1 has not been fully investigated. Exploring the interaction will contribute to discover the molecular pathways disrupted in DiGeorge/del22q11 syndrome, and will also be essential for understanding genetic basis for congenital heart disease. It now seems possible that genes and molecular pathways disrupted in DiGeorge syndrome will also account for some isolated cases of congenital heart disease. Accordingly, the present study aimed to extensively study the effects of external RA on the cardiac development and Tbx1 expression during zebrafish embryogenesis.

METHODSThe chemical genetics approach was applied by treating zebrafish embryos with 5 x 10(-8) mol/L RA and 10(-7) mol/L RA at 12.5 hour post fertilization (hpf). The expression patterns of Tbx1 were monitored by whole-mount in situ hybridization and quantitative real-time RT-PCR, respectively.

RESULTSThe zebrafish embryos treated with 5 x 10(-8) mol/L RA and 10(-7) mol/L RA for 1.5 h at 12.5 hpf exhibited selective defects of abnormal heart tube. The results of whole-mount in situ hybridization with Tbx1 RNA probe showed that Tbx1 was expressed in cardiac region, pharyngeal arches and otic vesicle during zebrafish embryogenesis. RA treatment led to a distinct spatio-temporal expression pattern for Tbx1 from that in wild type embryo. The real-time PCR analysis showed that Tbx1 expression levels were markedly reduced by RA treatment. Tbx1 expression in the pharyngeal arches and heart were obviously down regulated compared to the wild type embryos. In contrast to 5 x 10(-8) mol/L RA-treated groups, 10(-7) mol/L RA caused a more severe effect on the Tbx1 expression level.

CONCLUSIONThese results suggested that there was a genetic link between RA and Tbx1 during development of zebrafish embryo. RA could produce an altered Tbx1 expression pattern in zebrafish. RA may regulate the Tbx1 expression in a dose-dependant manner. RA could represent a major epigenetic factor to cause abnormal expression of Tbx1, secondarily, disrupt the pharyngeal arch and heart development.

Animals ; Branchial Region ; drug effects ; embryology ; Embryo, Nonmammalian ; drug effects ; Embryonic Development ; drug effects ; Gene Expression Regulation, Developmental ; Heart ; drug effects ; embryology ; T-Box Domain Proteins ; genetics ; metabolism ; Tretinoin ; pharmacology ; Zebrafish ; embryology ; genetics ; Zebrafish Proteins ; genetics ; metabolism

BACKGROUNDFolic acid is very important for embryonic development and dihydrofolate reductase is one of the key enzymes in the process of folic acid performing its biological function. Therefore, the dysfunction of dihydrofolate reductase can inhibit the function of folic acid and finally cause the developmental malformations. In this study, we observed the abnormal cardiac phenotypes in dihydrofolate reductase (DHFR) gene knock-down zebrafish embryos, investigated the effect of DHFR on the expression of heart and neural crest derivatives expressed transcript 2 (HAND2) and explored the possible mechanism of DHFR knock-down inducing zebrafish cardiac malformations.

METHODSMorpholino oligonucleotides were microinjected into fertilized eggs to knock down the functions of DHFR or HAND2. Full length of HAND2 mRNA which was transcribed in vitro was microinjected into fertilized eggs to overexpress HAND2. The cardiac morphologies, the heart rates and the ventricular shortening fraction were observed and recorded under the microscope at 48 hours post fertilization. Whole-mount in situ hybridization and real-time PCR were performed to detect HAND2 expression.

RESULTSDHFR or HAND2 knock-down caused the cardiac malformation in zebrafish. The expression of HAND2 was obviously reduced in DHFR knock-down embryos (P < 0.05). Microinjecting HAND2 mRNA into fertilized eggs can induce HAND2 overexpression. HAND2 overexpression rescued the cardiac malformation phenotypes of DHFR knock-down embryos.

CONCLUSIONSDHFR plays a crucial role in cardiac development. The down-regulation of HAND2 caused by DHFR knock-down is the possible mechanism of DHFR knock-down inducing the cardiac malformation.

Animals ; Basic Helix-Loop-Helix Transcription Factors ; genetics ; physiology ; Female ; Heart ; embryology ; Heart Defects, Congenital ; etiology ; Tetrahydrofolate Dehydrogenase ; genetics ; physiology ; Zebrafish ; Zebrafish Proteins ; genetics ; physiology

OBJECTIVETo investigate the effect of lead exposure on the gene expression of fibroblast growth factor 3 (Fgf3) in zebrafish embryonic development and the mechanism of lead-induced embryonic developmental toxicity.

METHODSThe embryos of zebrafish (wild types A and B) were exposed to lead acetate (PbAc) at the doses of 0, 0.1, 0.5, 2.5, and 12.5 µmol/L separately. Total RNA was extracted from each treatment group of zebrafish embryos at 8, 12, 16, 24, 36, 48, and 72 hours post fertilization (hpf). The total mRNA expression of Fgf3 was measured by real-time quantitative PCR. The spatial expression of Fgf3 in zebrafish embryos was determined by whole-mount in situ hybridization using synthesized Fgf3 RNA probe.

RESULTSThe mRNA expression of Fgf3 in each group peaked at 12 hpf (P < 0.01). With the increase in PbAc concentration, the mRNA expression of Fgf3 rose. Compared with the mRNA expression level of Fgf3 in the control group, the relative mRNA expression levels of Fgf3 in the 0.1, 0.5, 2.5, and 12.5 µmol/L PbAc exposure groups were 1.02 ± 0.24, 1.05 ± 0.26, 1.22 ± 0.46, and 1.25 ± 0.38, respectively, and the 2.5 and 12.5 µmol/L PbAc exposure groups showed significantly higher Fgf3 expression than the control group (P < 0.05). The whole-mount in situ hybridization results showed that Fgf3 expression occurred mainly in the head and tail in the early stage of embryonic development and in the midbrain, fin bud, and pharyngeal arch in the middle/late stage of embryonic development; there were the most significant regions and intensities of positive hybridization signals at 12 hpf; but no significant differences were found between the control group and exposure groups in the location and intensity of Fgf3 expression

CONCLUSIONLead exposure can result in the upregulation of Fgf3 expression in zebrafish embryonic development, which might contribute to lead-induced embryonic developmental toxicity.

Animals ; Embryonic Development ; drug effects ; Fibroblast Growth Factor 3 ; genetics ; metabolism ; Gene Expression ; Organometallic Compounds ; adverse effects ; Signal Transduction ; Zebrafish ; embryology ; genetics ; metabolism ; Zebrafish Proteins ; genetics ; metabolism

OBJECTIVE: : To observe the expression of gene in the early development stage of wild zebrafish embryos. METHODS: : The collinearity of gene and the sequence similarity of G6pd protein were analyzed with gene database and BLAST software, respectively. Expression of gene in different development stages of zebrafish embryos was detected by hybridization. The -EGFP-pCS recombinant plasmids were microinjected into zebrafish embryos, and fluorescence was observed under a fluorescence microscope. The expression of G6pd protein at 24, 48 and 72 hour post fertilization (hpf) zebrafish embryos was detected by Western blotting; the enzyme activity of G6pd at 24, 48 and 72 hpf zebrafish embryos was detected by modified G6pd quantitative ratio method. RESULTS: : The G6pd protein similarity of zebrafish and human was 88%, and that of zebrafish and mouse was 87%. The results of hybridization showed that the gene was mainly expressed in the hematopoietic tissues of zebrafish; the results observed after microinjection of -EGFP-pCS recombinant plasmid were consistent with the results of hybridization. At 24, 48 and 72 hpf, the relative expression levels of G6pd protein in zebrafish embryos were 1.44±0.03, 1.47±0.05, and 1.54±0.02, respectively(>0.05); the G6pd enzyme activity levels were 1.74±0.17, 1.75±0.12, 1.71±0.22, respectively (>0.05). CONCLUSIONS : The study has observed the expression of gene and G6pd protein, and G6pd enzyme activity in zebrafish embryos at different development phases, which provides a reference for the establishment of a zebrafish G6PD deficiency model.
Animals ; Embryo, Nonmammalian ; Gene Expression Regulation, Developmental ; Glucosephosphate Dehydrogenase ; genetics ; Humans ; In Situ Hybridization ; Mice ; Plasmids ; genetics ; Zebrafish ; embryology ; genetics