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At least 91 records · Page 5Linked to original sources

PubMed2003

Effects of 17a-ethinylestradiol on the expression of three estrogen-responsive genes and cellular ultrastructure of liver and testes in male zebrafish.

In order to monitor the influence of estrogenic compounds on the reproductive physiology of fish, molecular markers for zebrafish vitellogenin, estrogen receptor and ZP2 were developed. For this purpose, sequence information about the zebrafish estrogen receptor and vitellogenin had to be obtained. By means of RT-PCR, a sequence fragment of the zebrafish estrogen receptor alpha was cloned and sequenced. Continuous cDNAs of two zebrafish vitellogenin-like gene products (zfvg1 and zfvg3) were constructed by the help of expressed sequence tags of zebrafish and completely sequenced. The sequences of the estrogen receptor and of the vitellogenins showed significant similarities to corresponding cDNAs of other fish species. Expression of these gene products was measured following exposure to 17alpha-ethinylestradiol and compared with histological endpoints. RT-PCR was used as a semiquantitative technique to record gene expression in adult male zebrafish, which were exposed to 17alpha-ethinylestradiol in time-and dose-response experiments. As for time-dependent expression, all hepatic genes investigated were expressed at considerable amounts from 24 h after onset of exposure to 50 ng/l 17alpha-ethinylestradiol to the end of experiment (17 days). In testes, expression of the estrogen receptor- as well as ZP2-mRNA remained unchanged for the entire experiment, except for the individuals exposed for 17 days, which displayed elevated expression levels of ZP2. In the dose-response experiment, male zebrafish were exposed to 17alpha-ethinylestradiol in concentrations from 0.25-85 ng/l for 4 and 21 days. LOECs for vitellogenin as well as estrogen receptor alpha expression were found to be 2.5 ng/l already after 4 d of exposure. Extension of the exposure time to 21 days resulted in enhanced transcription of vitellogenin-mRNAs at 2.5 ng/l 17alpha-ethinylestradiol, whereas the detection limit could not be lowered. In contrast, in testes no induction of both ZP2 as well as estrogen receptor expression was detected at any concentration tested. To examine estrogen-caused alterations at the ultrastructural level, liver and testes of males exposed to 25 ng/l 17alpha-ethinylestradiol were analysed. Male livers responded with a feminisation reflected by the proliferation of rough endoplasmatic reticulum and Golgi apparatus typical of female hepatocytes during vitellogenesis. However, in testes no signs of feminisation were detectable; rather, destructive phenomena like phagocytosis of sperm cells by Sertoli cells were observed. Thus, in sexually differentiated males no reorganisation of the gonadal tissue towards an ovary could be definitely detected at any level investigated.

Animals↗

PubMed2002

Assessment of zebrafish cardiac performance using Doppler echocardiography and power angiography.

The zebrafish (Danio rerio) has become a new animal model for cardiac researches. Although it is equipped with a prototypical vertebrate heart, the zebrafish studies for cardiac mutations and genetic control of development can reveal some hints for solving human problems. Despite the simplicity of the zebrafish heart, the objective parameters of cardiac performance are not easily available, except for the morphological description, due to its small size. Because the four components (sinus venosus, atrium, ventricle and bulbus arteriosus) of the zebrafish heart are connected in series, we studied it by applying ultrasonic imaging methods for the vascular system. A total of 20 fishes that were ages of 3 to 4 months were studied. Their mean body weight and height were 562 +/- 173 mg and 4.6 +/- 0.7 cm, respectively. Power angiography and routine Doppler echocardiography were used to evaluate the cardiac performance of zebrafish at 25 degrees C and 15 degrees C. The zebrafish hearts could be easily identified with color Doppler (8.5 MHz) or power angiography (7 MHz). The ventricular filling flow contained two components (E and A-flow). The E-flow velocities were lower than the A-flow velocities at both 25 and 15 degrees C. The cycle length was prolonged (p < 0.05) and the velocities of ventricular filling and bulbus arteriosus decreased significantly at 15 degrees C (p < 0.05). A significant decrease in early diastolic deceleration slope and significant prolongation in early diastolic and late-diastolic deceleration times were found at a lower temperature (15 degrees C). The acceleration:deceleration ratio for early and late diastole also showed a significant difference at 15 degrees C. In conclusion, the cardiac performance of the zebrafish could be approached using commercially available clinical instruments equipped with Doppler echocardiography and power angiography.

Anesthetics↗

PubMed1999

Tenascin-C expression in the trunk of wild-type, cyclops and floating head zebrafish embryos.

The function and the regulation of the expression of the extracellular matrix molecule tenascin-C during embryonic development are still unclear. In the present study, the expression of tenascin-C was analyzed in the trunk of zebrafish at the end of the first embryonic day. An antiserum raised against a zebrafish tenascin-C (TN-C) fusion protein reacted with 220 (doublet), 200, and 160 KD peptides. In situ hybridization showed that in the zebrafish wild-type embryo, tn-c mRNA was expressed by somites, neural crest cells, roof plate, notochord, hypochord, and tail fin bud. Thus, the expression of tn-c mRNA is an excellent marker for the differentiation of most zebrafish trunk structures. Immunolabelling with the anti-TN-C antibody was detected in the migratory pathway of neural crest cells and in the intersomitic furrows. In situ hybridization analysis of the zebrafish cyclops mutants, lacking the midline floor plate cells, showed normal expression of tn-c mRNA in all trunk structures. Analysis of the floating-head mutant, lacking the notochord, showed that tn-c mRNA expression in neural crest cells, roof plate, and tail fin bud is normal, but it is defective in the somites. By showing that the notochord, but not the floor plate, cells are required for normal tn-c expression in the trunk, this work provides new information on the role played by the embryonic axial structures in the regulation of the expression of tn-c during the development of zebrafish and allows new conclusions about somite patterning in the cyclops and floating-head zebrafish mutants.

Animals↗

PubMed2000

The zebrafish fth1, slc3a2, men1, pc, fgf3 and cycd1 genes define two regions of conserved synteny between linkage group 7 and human chromosome 11q13.

In addition to being an excellent model system for studying vertebrate development, the zebrafish has become a great tool for gene discovery by mutational analysis. The recent availability of the zebrafish EST database and radiation hybrid mapping panels has dramatically expanded the framework for genomic research in this species. Developing comparative maps of the zebrafish and human genomes is of particular importance for zebrafish mutagenesis studies in which human orthologs are sought for zebrafish genes. However, only partial cDNA sequences are determined routinely for mapped ESTs, leaving the identity of the EST in question. It previously had been reported that zebrafish linkage group 7 shares conserved synteny with human chromosome 11q13. In an effort to further define this relationship, five full-length zebrafish cDNAs, fth1, slc3a2, prkri, cd81, and pc, as well as one putative human gene, DBX were identified and their map positions ascertained. These six genes, along with men1, fgf3 and cycd1 define two regions of conserved synteny between linkage group 7 and 11q13.

Amino Acid Sequence↗

PubMedDate not supplied

Chlorpyrifos exposure of developing zebrafish: effects on survival and long-term effects on response latency and spatial discrimination.

Chlorpyrifos (CPF) is a widely used insecticide, which has been shown to interfere with neurobehavioral development. Rat models have been key in demonstrating that prenatal CPF exposure causes choice accuracy deficits and motor alterations, which persist into adulthood. Complementary nonmammalian models can be useful in determining the molecular mechanisms underlying the persisting behavioral effects of developmental CPF exposure. Zebrafish with their clear chorion and extensive developmental information base provide an excellent model for assessment of molecular processes of toxicant impacted neurodevelopment. To facilitate the use of the zebrafish model and to compare it to the more typical rodent models, the behavioral phenotype of CPF toxicity in zebrafish must be well characterized. Our laboratory has developed methods for assessing spatial discrimination learning in zebrafish, which can differentiate response latency from choice accuracy in a three chambered fish tank. Low and high doses of CPF (10 and 100 ng/ml on days 1-5 postfertilization) both had significant persisting effects on both spatial discrimination and response latency over 18 weeks of testing. The high, but not the low dose, significantly accelerated mortality rates of the fish during the study from 20-38 weeks of age. Developmental exposure to either 10 or 100 ng/ml of CPF caused significant spatial discrimination impairments in zebrafish when they were adults. The impairment caused by 10 ng/ml was seen during early but not later testing, while the impairment caused by 100 ng/ml became more pronounced with continued testing. The higher dose caused a more pervasive impairment. The 10 and 100 ng/ml doses had opposite effects on response latency. The low 10 ng/ml dose significantly slowed response latency, while the high 100 ng/ml dose significant increased response latency. Both of these effects diminished with continued testing. CPF exposure during early development caused clear behavioral impairments, which lasted throughout adulthood in zebrafish. The molecular mechanisms by which early developmental CPF exposure produces these behavioral impairments expressed in adulthood can now be studied in the zebrafish model.

Animals↗

PubMed2001

Development and validation of a homologous zebrafish (Danio rerio Hamilton-Buchanan) vitellogenin enzyme-linked immunosorbent assay (ELISA) and its application for studies on estrogenic chemicals.

Vitellogenin (VTG) was isolated by anion exchange chromatography from plasma of female zebrafish (Danio rerio) induced with 17alpha-ethinylestradiol (EE2). The purity of the VTG isolate was confirmed by polyacrylamide gel electrophoresis (SDS-PAGE). Purified VTG was used to raise polyclonal antibodies in rabbits and the specificity of the antisera for VTG confirmed by Western blot analysis of plasma proteins separated by SDS-PAGE. The antibodies cross-reacted with two proteins in the plasma of female zebrafish, with molecular masses of approximately 142 and 171 kDa. No cross-reactivity was observed with any other plasma proteins. A competitive enzyme-linked immunosorbent assay (ELISA) was developed using the polyclonal zebrafish VTG (z-VTG) antibodies and purified z-VTG as ligand and standard, respectively. The z-VTG ELISA was sensitive with a detection limit of between 2.0 and 3.0 ng purified VTG/ml, and a working range between 3 and 500 ng/ml (30-85% binding). The ELISA demonstrated precision, with inter- and intra-assay variations of 7.5+/-2.7 and 4.9+/-1.4%, respectively. Plasma from adult zebrafish and whole body homogenates from juvenile zebrafish diluted parallel with the z-VTG standard in the ELISA, validating the assay for quantifying z-VTG in both of these tissues. Exposure of adult male zebrafish to EE2 via water induced a concentration-dependent induction of VTG with a lowest observed effect concentration (LOEC) < or =1.67 ng EE2/l (for a 21-day exposure). The homologous z-VTG ELISA provides a valuable tool for the study of environmental estrogens in zebrafish.

Animals↗

PubMed2000

Ethylnitrosourea induces neoplasia in zebrafish (Danio rerio).

The zebrafish (Danio rerio) has been successfully used to discover hundreds of genes involved in development and organogenesis. To address the potential of zebrafish as a cancer model, it is important to determine the susceptibility of zebrafish to tumors. Germ line mutations are most commonly induced for zebrafish mutant screens by exposing adult male zebrafish to the alkylating agent, ethylnitrosourea (ENU). To determine whether ENU induces tumors, we compared the incidence of tumors in ENU-treated fish with untreated controls. Interestingly, 18 of 18 (100%) fish mutagenized with either 2.5 or 3.0 mM ENU developed epidermal papillomas, which numbered 1 to 22 per fish, within 1 year of treatment. The induced epidermal lesions included epidermal hyperplasia, flat papillomas (0.2 to 1.2 mm), and pedunculated papillomas (1.2 to 8 mm in greatest dimension), but no skin cancers. Angiogenesis was evident in papillomas larger than approximately 1 mm. All but two papillomas contained the three cell types (keratinocytes, club, and mucous cells) of normal zebrafish epidermis; histologic variants lacked either club cells or mucous cells. Two cavernous hemangiomas and a single malignant peripheral nerve sheath tumor were also found in the treated fish. None of five untreated controls developed tumors. These studies establish the feasibility of the zebrafish as an experimental model for the study of skin tumors.

Animals↗

PubMed2000

Identification of a histamine H(3)-like receptor in the zebrafish (Danio rerio) brain.

The distribution of histaminergic fibers in the zebrafish brain was recently shown to resemble that in mammals. Expression of L-histidine decarboxylase (HDC) mRNA was shown only in the area corresponding to that expressing HDC in mammals. This indicates that the zebrafish could be a useful model for studies on the function of the brain histaminergic system. In this study an H(3)-like receptor is identified in zebrafish brain. With binding studies using N-alpha-[(3)H]methylhistamine on zebrafish brain sections, signals were observed in several regions. Highest densities were detected in optic tectum and hypothalamus. The autoradiographic signal was abolished completely by the H(3)-specific antagonist clobenpropit and significantly reduced by another H(3) antagonist, thioperamide. Histamine and immepip induced an increase of guanosine 5'-(gamma-[(35)S]thio)triphosphate binding in several areas of the zebrafish brain. The activation was blocked with clobenpropit but not with cimetidine or mepyramine. These results indicate that the zebrafish has a histamine H(3)-like receptor that functionally interacts with the inhibitory, G(i)/G(o), class of G proteins. No previous evidence for a histamine receptor in zebrafish exists. The receptor described here is apparently similar to the mammalian H(3) receptor, making this the first description of a histamine H(3)-like receptor in a lower vertebrate.

Animals↗

PubMed2000

Evidence for gelsolin as a corneal crystallin in zebrafish.

We have shown that gelsolin is one of the most prevalent water-soluble proteins in the transparent cornea of zebrafish. There are also significant amounts of actin. In contrast to actin, gelsolin is barely detectable in other eye tissues (iris, lens, and remaining eye) of the zebrafish. Gelsolin cDNA hybridized intensely in Northern blots to RNA from the cornea but not from the lens, brain, or headless body. The deduced zebrafish gelsolin is approximately 60% identical to mammalian cytosolic gelsolin and has the characteristic six segmental repeats as well as the binding sites for actin, calcium, and phosphatidylinositides. In situ hybridization tests showed that gelsolin mRNA is concentrated in the zebrafish corneal epithelium. The zebrafish corneal epithelium stains very weakly with rhodamine-phalloidin, indicating little F-actin in the cytoplasm. In contrast, the mouse corneal epithelium contains relatively little gelsolin and stains intensely with rhodamine-phalloidin, as does the zebrafish extraocular muscle. We propose, by analogy with the diverse crystallins of the eye lens and with the putative enzyme-crystallins (aldehyde dehydrogenase class 3 and other enzymes) of the mammalian cornea, that gelsolin and actin-gelsolin complexes act as water-soluble crystallins in the zebrafish cornea and contribute to its optical properties.

Amino Acid Sequence↗

PubMed2002

Streptococcus-zebrafish model of bacterial pathogenesis.

Due to its small size, rapid generation time, powerful genetic systems, and genomic resources, the zebrafish has emerged as an important model of vertebrate development and human disease. Its well-developed adaptive and innate cellular immune systems make the zebrafish an ideal model for the study of infectious diseases. With a natural and important pathogen of fish, Streptococcus iniae, we have established a streptococcus- zebrafish model of bacterial pathogenesis. Following injection into the dorsal muscle, zebrafish developed a lethal infection, with a 50% lethal dose of 10(3) CFU, and died within 2 to 3 days. The pathogenesis of infection resembled that of S. iniae in farmed fish populations and that of several important human streptococcal diseases and was characterized by an initial focal necrotic lesion that rapidly progressed to invasion of the pathogen into all major organ systems, including the brain. Zebrafish were also susceptible to infection by the human pathogen Streptococcus pyogenes. However, disease was characterized by a marked absence of inflammation, large numbers of extracellular streptococci in the dorsal muscle, and extensive myonecrosis that occurred far in advance of any systemic invasion. The genetic systems available for streptococci, including a novel method of mutagenesis which targets genes whose products are exported, were used to identify several mutants attenuated for virulence in zebrafish. This combination of a genetically amenable pathogen with a well-defined vertebrate host makes the streptococcus-zebrafish model of bacterial pathogenesis a powerful model for analysis of infectious disease.

Animals↗

PubMed1998

Zebrafish hox genes: genomic organization and modified colinear expression patterns in the trunk.

The Hox genes are implicated in conferring regional identity to the anteroposterior axis of the developing embryo. We have characterized the organization and expression of hox genes in the teleost zebrafish (Danio rerio), and compared our findings with those made for the tetrapod vertebrates. We have isolated 32 zebrafish hox genes, primarily via 3'RACE-PCR, and analyzed their linkage relationships using somatic cell hybrids. We find that in comparison to the tetrapods, zebrafish has several additional hox genes, both within and beyond the expected 4 hox clusters (A-D). For example, we have isolated a member of hox paralogue group 8 lying on the hoxa cluster, and a member of hox paralogue group 10 lying on the b cluster, no equivalent genes have been reported for mouse or human. Beyond the 4 clusters (A-D) we have isolated a further 3 hox genes (the hoxx and y genes), which according to their sequence homologies lie in paralogue groups 4, 6, and 9. The hoxx4 and hoxx9 genes occur on the same set of hybrid chromosomes, hinting at the possibility of an additional hox cluster for the zebrafish. Similar to their tetrapod counterparts, zebrafish hox genes (including those with no direct tetrapod equivalent) demonstrate colinear expression along the anteroposterior (AP) axis of the embryo. However, in comparison to the tetrapods, anterior hox expression limits are compacted over a short AP region; some members of adjacent paralogue groups have equivalent limits. It has been proposed that during vertebrate evolution, the anterior limits of Hox gene expression have become dispersed along the AP axis allowing the genes to take on novel patterning roles and thus leading to increased axial complexity. In the teleost zebrafish, axial organization is relatively simple in comparison to that of the tetrapod vertebrates; this may be reflected by the less dispersed expression domains of the zebrafish hox genes.

Amino Acid Sequence↗

PubMed2000

Laser-induced gene expression in specific cells of transgenic zebrafish.

Over the past few years, a number of studies have described the generation of transgenic lines of zebrafish in which expression of reporters was driven by a variety of promoters. These lines opened up the real possibility that transgenics could be used to complement the genetic analysis of zebrafish development. Transgenic lines in which the expression of genes can be regulated both in space and time would be especially useful. Therefore, we have cloned the zebrafish promoter for the inducible hsp70 gene and made stable transgenic lines of zebrafish that express the reporter green fluorescent protein gene under the control of a hsp70 promoter. At normal temperatures, green fluorescent protein is not detectable in transgenic embryos with the exception of the lens, but is robustly expressed throughout the embryo following an increase in ambient temperature. Furthermore, we have taken advantage of the accessibility and optical clarity of the embryos to express green fluorescent protein in individual cells by focussing a sublethal laser microbeam onto them. The targeted cells appear to develop normally: cells migrate normally, neurons project axons that follow normal pathways, and progenitor cells divide and give rise to normal progeny cells. By generating other transgenic lines in which the hsp70 promoter regulates genes of interest, it should be possible to examine the in vivo activity of the gene products by laser-inducing specific cells to express them in zebrafish embryos. As a first test, we laser-induced single muscle cells to make zebrafish Sema3A1, a semaphorin that is repulsive for specific growth cones, in a hsp70-sema3A1 transgenic line of zebrafish and found that extension by the motor axons was retarded by the induced muscle.

Animals↗

PubMed2026

Zebrafish as a Model Organism to Study Neurotoxicity: A Potential Tool for Neuroprotective Drug Discovery.

INTRODUCTION: Danio rerio, the zebrafish, serves as an excellent model in neuroprotective drug discovery due to its conserved nervous system organization, neurotransmitter pathways, antioxidant defenses, and genomic similarity to mammals. METHODS: A systematic literature search following PRISMA 2020 guidelines was conducted across Pub- Med, Scopus, Web of Science, and Google Scholar. Studies published between 2020 and 2025 were prioritized, with earlier key papers included for context. The data on larval, adult, and genetically modified zebrafish models were analyzed for neurotoxic effects, focusing on study design, toxicants, and neurobehavioral or molecular outcomes. RESULTS: Neurotoxicants such as chlorpyrifos, bisphenol, triphenyl phosphate, aluminum, ammonium acetate, arsenic, zinc, acrylamide, methylmercury, and tris (1,3-dichloro-2-propyl) phosphate were shown to cross the zebrafish blood-brain barrier. These exposures caused significant behavioral alterations, neurotransmitter imbalances, oxidative stress, and gene or protein expression changes related to brain function. Analysis of the transgenic zebrafish revealed notable alterations in neuronal development and axonal morphology upon exposure to various neurotoxic chemicals. DISCUSSION: Zebrafish display neurotoxic responses with a close resemblance to mammals, supporting their translational value in neurotoxicity and drug discovery studies. However, limitations such as a less complex brain compared to mammals, quick neuronal regeneration, limited tissue access, and difficulties in drug absorption quantification warrant refinements in zebrafish models. CONCLUSION: Zebrafish offer a versatile, cost-effective, and genetically tractable system for neurotoxicity and neuroprotection research. This systematic review highlights their crucial role in neuroprotective drug discovery while emphasizing the need for improved methodological approaches to enhance translational reliability.

Animals↗

PubMed2002

The zebrafish as a model for human disease.

Much of our current understanding of the function of genes modulating the normal process of embryonic development has come from mutant analysis. The availability of thousands of mutant lines in zebrafish that allows for identification of novel genes regulating various aspects of embryogenesis has been instrumental in establishing zebrafish as a robust and reliable genetic system. With the advances in genomic sequencing, the construction of several genetic maps, and cloning of hundreds of ESTs, positional cloning experiments in zebrafish have become more approachable. An increasing number of mutant genes have been cloned. Several zebrafish mutants are representative of known forms of human genetic diseases. The success of morpholino antisense technology in zebrafish potentially opens the door for modeling nearly any inherited developmental defect. This review highlights the strengths and limitations of using the zebrafish as an organism for elucidation of the genetic etiology of human disease. Additionally a survey of current and future zebrafish models of human disease is presented.

Animals↗

PubMed2002

Sequence and spatial expression of zebrafish (Danio rerio) alphaA-crystallin.

PURPOSE: To determine the nucleotide sequence, amino acid sequence and tissue specificity of zebrafish alphaA-crystallin. METHODS: RACE, both 3' and 5', was used to clone the zebrafish alphaA-crystallin gene. The peptide sequence of the encoded protein was deduced and compared to cavefish, shark, amphibian, bird and human orthologues using the CLUSTAL W algorithm. alphaA-crystallin transcript was evaluated in brain, heart, lens, liver, skeletal muscle/skin, and spleen by semi-quantitative RT-PCR. RESULTS: The 173 amino acid sequence of zebrafish alphaA-crystallin was determined to be 73% and 86% similar to its human and cavefish orthologues, respectively. We detected high expression of zebrafish alphaA-crystallin in the lens and very low expression in liver and spleen. CONCLUSIONS: Few amino acids identified as being functionally important to chaperone function differ between zebrafish and mammalian alphaA-crystallin. The expression of alphaA-crystallin is mainly confined to the lens in both taxa. These data suggest that zebrafish alphaA-crystallin plays a physiologically limited role outside of the zebrafish lens, similar to its mammalian orthologues.

Amino Acid Sequence↗

PubMed2003

The dystrophin associated protein complex in zebrafish.

Many cases of muscular dystrophy in humans are caused by mutations in members of the dystrophin associated protein complex (DAPC). Zebrafish are small vertebrates whose bodies are composed predominantly of skeletal muscle, making them attractive models for studying mammalian muscle disorders. Potential orthologs to most of the human DAPC proteins have been found in zebrafish by database screening. Expression of the sarcoglycans, dystroglycan and dystrophin has been confirmed by western blotting. Immunohistochemical and biochemical techniques localize these proteins to the muscle cell membrane in adult zebrafish. Morpholino (MO) experiments designed to inhibit the translation of dystrophin mRNA produce juvenile zebrafish that are less active than zebrafish injected with control morpholinos. Western blot analysis of the dystrophin morpholino-injected zebrafish shows concurrent reduction of dystrophin and the sarcoglycans, suggesting that these proteins, like those in mammals, are part of a complex whose integrity is dependent on dystrophin expression. These results indicate that the zebrafish is an excellent animal model in which to approach the study of dystrophin and its associated proteins.

Amino Acid Sequence↗

PubMed1996

The zebrafish ultraviolet cone opsin reported previously is expressed in rods.

PURPOSE: To examine expression of the zebrafish ultraviolet cone opsin pigment in goldfish and zebrafish retinas. METHODS: Digoxigenin-labeled cRNA probes were prepared by run-off transcription from plasmids containing cDNAs for zebrafish ultraviolet opsin, goldfish ultraviolet cone opsin, and goldfish rod opsin. Probes were hybridized to cryosections of retina and visualized with immunocytochemistry. RESULTS: The zebrafish ultraviolet opsin probe hybridized selectively to rod photoreceptors, but not to ultraviolet cones or any other cone type, in both zebrafish and goldfish retinas, and the pattern of expression was identical to that of the goldfish rod opsin probe. The goldfish ultraviolet opsin, in contrast, hybridized to ultraviolet cone photoreceptors in both goldfish and zebrafish. CONCLUSIONS: The cDNA previously identified by Robinson et al as zebrafish ultraviolet opsin is not a cone opsin but is likely to be a rod opsin.

Animals↗

PubMed1997

Zebrafish (Danio rerio) p53 tumor suppressor gene: cDNA sequence and expression during embryogenesis.

Three methods were used in succession to screen a whole adult zebrafish cDNA library for expressed p53-like genes. The sequences of the resultant clones describe an open reading frame 1122 nucleotides in length, with another 43 and 940 bases of 5' and 3' untranslated sequence, respectively. The deduced amino acid sequence of the zebrafish p53 protein is 63% identical to that of trout and 48% identical to that of human p53. Two of the three zebrafish clones overlap to span the entire reported cDNA sequence and are identical in their deduced amino acid sequence over their coincident length. The third clone contains a conservative amino acid change, as well as an inserted amino acid subsequently found to be at the junction of exons 2 and 3, suggestive of alternative splicing in the p53 mRNA for this species. Northern analysis demonstrated a zebrafish p53-related transcript to be present and most abundant in zygotes and early-cleavage embryos less than 1 hour after fertilization, thereafter declining to barely detectable levels at 48 hours. A similar temporal expression was detected for the zebrafish L-myc, known to be present in maternally derived RNA, whereas zebrafish N-myc and the zebrafish homologue of the murine T gene were not detectable prior to the onset of zygotic transcription.

Alternative Splicing↗