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PubMed2006

Vitellogenin 1 mRNA as an early molecular biomarker for endocrine disruption in developing zebrafish (Danio rerio).

Contemporary ecotoxicology is faced with the challenge of mechanistic understanding, a prerequisite for advanced risk assessment where acute toxicity is not the main issue. To achieve this, bioassay systems that are fast and biologically integrating and that detect a multitude of effects on a molecular level are needed. We present here the concept of such a novel test system that is built on the Danio rerio teratogenicity (DarT) assay but is extended in time and is based on testing molecular effects in the subacute toxicity range, named MolDarT. As proof of principle, we show the use of measuring vitellogenin 1 gene (vtg1) mRNA levels as a molecular marker for estrogenicity in developing zebrafish, a first module of MolDarT. Fertilized zebrafish eggs were exposed to 100, 1,000, and 2,000 ng/L (6.75 nM) 17 alpha-ethinylestradiol (EE2), and total RNA was isolated every 24 h up to 120 h postfertilization (hpf). Abundance of vtg1 mRNA was detected using reverse transcription real-time polymerase chain reaction and normalized to beta-actin mRNA abundance. Between 48 and 120 hpf, beta-actin mRNA levels were constant, making this gene a suitable reference gene for normalization. A significant up-regulation of vtg1 expression was detected at 48 hpf for 1,000 and 2,000 ng/L EE2. At 72, 96, and 120 hpf, vtg1 was significantly induced for all EE2 concentrations. Expression of vtg1 was also measured in unexposed developing zebrafish. At 24 hpf and at all later time points, zebrafish embryos contained vtg1 transcripts. These findings show that vtg1 is regularly expressed in developing zebrafish and that it is inducible by EE2. We propose the use of vtg1 as molecular target for estrogenicity in the MolDarT.

Actins↗

PubMed2003

DNA delivery into anterior neural tube of zebrafish embryos by electroporation.

The zebrafish is widely used for functional studies of vertebrate genes. It is accessible to manipulations during all stages of embryogenesis because the embryo develops externally and is optically transparent. However, functional studies conducted on the zebrafish have been generally limited to the earliest phase of activity of the gene of interest, which is a limitation in studies of genes that are expressed at various stages of embryonic development. It is therefore necessary to develop methods that allow for the modulation of gene activity during later stages of zebrafish development while leaving earlier functions intact. We have successfully electroporated the green fluorescent protein (GFP) reporter gene into the neural tube of the zebrafish embryo in a unidirectional or bilateral manner. This approach can be used for the functional analysis of the late role of developmental genes in the neural tube of zebrafish embryo and larvae.

Animals↗

PubMed1999

A genetic linkage map for zebrafish: comparative analysis and localization of genes and expressed sequences.

Genetic screens in zebrafish (Danio rerio) have isolated mutations in hundreds of genes with essential functions. To facilitate the identification of candidate genes for these mutations, we have genetically mapped 104 genes and expressed sequence tags by scoring single-strand conformational polymorphisms in a panel of haploid siblings. To integrate this map with existing genetic maps, we also scored 275 previously mapped genes, microsatellites, and sequence-tagged sites in the same haploid panel. Systematic phylogenetic analysis defined likely mammalian orthologs of mapped zebrafish genes, and comparison of map positions in zebrafish and mammals identified significant conservation of synteny. This comparative analysis also identified pairs of zebrafish genes that appear to be orthologous to single mammalian genes, suggesting that these genes arose in a genome duplication that occurred in the teleost lineage after the divergence of fish and mammal ancestors. This comparative map analysis will be useful in predicting the locations of zebrafish genes from mammalian gene maps and in understanding the evolution of the vertebrate genome.

Animals↗

PubMed1999

Inhibition of memory consolidation by antibodies against cell adhesion molecules after active avoidance conditioning in zebrafish.

Cell adhesion molecules are expected to play an important role in long-term storage of information in the central nervous system. Several of these glycoproteins, such as NCAM, L1, and the ependymins, express the HNK-1 carbohydrate structure, which is known to be involved in cell-cell and cell-matrix interactions. To investigate the contribution of the HNK-1 epitope and the secretory glycoproteins ependymins to memory formation in zebrafish (Brachydanio rerio), we developed an active avoidance conditioning paradigm. Zebrafish were trained in a shuttle-box to cross a hurdle, to avoid mild electric shocks following a conditioning light signal. One hour after acquisition of the task, zebrafish were injected intracerebroventricularly with monoclonal antibodies against the HNK-1 epitope or polyclonal antibodies against ependymins. Control fish received immunoglobulins G (IgGs) from nonimmune rat serum or the monoclonal antibody C183 against an unrelated cell-surface protein of the cyprinid brain. Two days later, injected zebrafish were tested for recall, and for quantitative evaluation a retention score (RS), ranging from 1.0 for immediate recall to 0.0, indicating no saving, was calculated. The average RS of anti-HNK-1-injected fish (RS = 0.30) and anti-ependymin-injected fish (0.24) were significantly different from the RS of uninjected fish (0.77), of controls injected with nonimmune serum IgGs (0.68), of C183-injected controls (0.78), and of overtrained fish injected with anti-HNK-1 antibodies (0.81). Anti-HNK-1 and anti-ependymin antibodies were characterized by Western blot analyses of subcellular brain fractions and immunohistochemical staining of the zebrafish optic tectum. Our data suggest that the antibodies influence cell recognition events at synaptic membranes and/or associated intracellular signaling cascades, and thereby block memory consolidation.

Animals↗

PubMed2000

Coordination between production and turnover of interphotoreceptor retinoid-binding protein in zebrafish.

PURPOSE: Interphotoreceptor retinoid-binding protein (IRBP), which is secreted by the photoreceptors of most vertebrates, is the major soluble protein component of the interphotoreceptor matrix (IPM). Recent studies suggest that IRBP is short lived in the IPM (half-life, approximately 11 hours). The mechanisms coordinating the production and removal of IRBP are not known. Zebrafish provide a useful system to study the regulation of these two processes, because its IRBP mRNA levels are under circadian regulation. In the present study, the relationship between the quantity of IRBP, the rate of its turnover, and the expression of its mRNA in the zebrafish retina were examined. METHODS: Full-length zebrafish IRBP was expressed in Escherichia coli and an antiserum generated against purified recombinant IRBP. Western and protein dot blot analyses and indirect immunofluorescence were used to define the temporal and spatial patterns of IRBP expression in the adult zebrafish. In vivo and in vitro metabolic labeling experiments were used to examine the regulation of IRBP turnover by both environmental light and the light-dark cycle. RESULTS: Despite the known rhythmicity in IRBP mRNA expression, neither the amount of IRBP nor its localization changes significantly during the light-dark cycle. IRBP is rapidly removed from the zebrafish eye (half life, approximately 7 hours). This rapid turnover is independent of environmental lighting conditions during subjective day and is more rapid during the day than at night. CONCLUSIONS: Because the amount of IRBP remains constant throughout the day, the enhanced daytime IRBP mRNA expression may function to compensate for an increased turnover of the protein during the day. These findings suggest that the processes of IRBP production and removal are coordinately regulated.

Animals↗

PubMed1992

Cell movements and cell fate during zebrafish gastrulation.

The early lineages of the zebrafish are indeterminate and a single cell labeled before the late blastula period will contribute progeny to a variety of tissues. Therefore, early cell lineages in the zebrafish do not establish future cell fates and early blastomeres must necessarily remain pluripotent. Eventually, after a period of random cell mixing, individual cells do become tissue restricted according to their later position within the blastoderm. The elucidation of a fate map for the zebrafish gastrula (Kimmel et al., 1990), has made it possible to study the processes by which cellular identity is conferred and maintained in the zebrafish. In this chapter, I describe single cell transplantation experiments designed to test for the irreversible restriction or 'commitment' of embryonic blastomeres in the zebrafish embryo. These experiments support the hypothesis that cell fate in the vertebrate embryo is determined by cell position. Work on the spadetail mutation will also be reviewed; this mutation causes a subset of mesodermal precursors to mismigrate during gastrulation thereby leading to a change in their eventual cell identity.

Animals↗

PubMed2004

Identification and characterization of human FHDC1, mouse Fhdc1 and zebrafish fhdc1 genes in silico.

Formin homology proteins, implicated in organogenesis and carcinogenesis, are actin regulators with scaffold function. FMNL1, FMNL2, FMNL3, DIAPH1, DIAPH2, DIAPH3, DAAM1 and DAAM2 are FDD-type Formin homology proteins, while FHOD1, FHOD3, GRID2IP, Fmn1 and Fmn2 are non-FDD-type Formin homology proteins. Here, we identified human FHDC1 gene and vertebrate FHDC1 orthologs by using bioinformatics. The complete coding sequence of human FHDC1 cDNA was determined by assembling 3'-recombinated FLJ35083 chimeric cDNA and 5'-truncated KIAA1727 (AB051514.1) partial cDNA. The complete coding sequence of mouse Fhdc1 cDNA was determined by assembling 3'-truncated CD555494 EST and 5'-truncated 6330505N24 (AK031946.1) partial cDNA. The complete coding sequence of zebrafish fhdc1 cDNA was determined by assembling fhdc1 exons within zebrafish genome clone DKEY-4A14 (BX571710.4). FHDC1 gene was located at human chromosome 4q31.3, and Fhdc1 gene at mouse chromosome 3F1. Human FHDC1 (1143 aa) showed 73.3% total amino-acid identity with mouse Fhdc1 (1148 aa), and 43.4% total amino-acid identity with zebrafish Fhdc1 (1165 aa). FDCH1-FDCH5 domains were identified as novel conserved regions among vertebrate FHDC1 orthologs. Human FHDC1, mouse Fhdc1, and zebrafish Fhdc1 were non-FDD-type Formin homology proteins with FH1 and FH2 domains in the N-terminal part as well as with FDCH1, FDCH2, FDCH3, FDCH4, and FDCH5 domains in the C-terminal part. This is the first report on the identification and characterization of the human FHDC1, mouse Fhdc1 and zebrafish fhdc1 genes.

Amino Acid Sequence↗

PubMed2006

Evaluation of xenoestrogenic potential of propylparaben in zebrafish (Danio rerio).

OBJECTIVES: Xenoestrogenic potential of propylparaben (PP), one of the most commonly used preservatives in drugs, cosmetics and food, was investigated in vivo using zebrafish (Danio rerio). METHODS: Juvenile zebrafish (20 days post hatching) were exposed to three different concentrations of propylparaben (PP) dissolved in ethanol and added into the water. After 20 days of exposure the fish were euthanized and vitellogenin concentrations in their whole body homogenates were measured by the method of direct sandwich ELISA. Simultaneously, vitellogenin concentrations in either fish from the control group (exposed to solvent without the substance tested) and in fish from the positive control group (exposed to natural estrogen 17beta-estradiol) were measured. RESULTS: Vitellogenin concentration in whole body homogenates of control fish was 400 (396-540) ng/ml(-1) (geometric mean (95% CI)). Zebrafish exposure to propylparaben at the concentrations of 0.1; 0.4 and 0.9 mg/l(-1) elicited statistically significant decline (P<0.001) of vitellogenin production, i.e. geometric means of vitellogenin concentrations in whole body homogenates were 240 (186-311); 218 (175-270) and 270 (234-311) ng/ml(-1), respectively. Conversely, the geometric mean of vitellogenin concentration in whole body homogenates of zebrafish exposed to 100 ng/ml(-1) of 17beta-estradiol (positive control) was significantly higher (P<0.001) than values in all other groups, i.e. 35,553 (16,860-74,968) ng/ml(-1). CONCLUSIONS: Our results suggest an antiestrogenic potential of propylparaben tested in vivo in juvenile zebrafish (Danio rerio). The estrogenic effect of 17beta-estradiol was confirmed.

Animals↗

PubMed1997

Spatially distinct domains of cell behavior in the zebrafish organizer region.

To determine the sequence of cell behaviors that is involved in the morphogenesis of the zebrafish organizer region, we have examined the dorsal marginal zone of vitally stained zebrafish embryos using time-lapse confocal microscopy. During the late-blastula stage, the zebrafish dorsal marginal zone segregates into several cellular domains, including a group of noninvoluting, highly endocytic marginal (NEM) cells. The NEM cell cluster, which lies in a superficial location of the dorsal marginal zone, is composed of both enveloping layer cells and one or two layers of underlying deep cells. The longitudinal position of this cellular domain accurately predicts the site of embryonic shield formation and occupies a homologous location to the organizer epithelium in Xenopus laevis. At the onset of gastrulation, deep cells underneath the superficial NEM cell domain undergo involution to form the nascent hypoblast of the embryonic shield. Deep cells within the NEM cell cluster, however, do not involute during early shield formation, but instead move in front of the blastoderm margin to form a loose mass of cells called forerunner cells. Forerunner cells coalesce into a wedge-shaped mass during late gastrulation and eventually become overlapped by the converging lateral lips of the germ ring. During early zebrafish tail elongation, most forerunner cells are incorporated into the epithelial lining of Kupffer's vesicle, a transient teleostean organ rudiment long thought to be an evolutionary vestige of the neurenteric canal. Owing to the location of NEM cells at the dorsal margin of blastula-stage embryos, as well as their early segregation from other deep cells, we hypothesized that NEM cells are specified by an early-acting dorsalizing signal. To test this possibility, we briefly treated early-blastula stage embryos with LiCl, an agent known to produce hyperdorsalized zebrafish embryos with varying degrees of expanded organizer tissue. In Li(+)-treated embryos, NEM cells appear either within expanded spatial domains or in ectopic locations, primarily within the marginal zone of the blastoderm. These results suggest that NEM cells represent a specific cell type that is specified by an early dorsal patterning pathway.

Animals↗

PubMed2001

Reconstitution of sperm nuclei of zebrafish (Danio rerio) in Xenopus egg extracts.

Cell-free extracts of Xenopus eggs cause cyclic change in permeabilized sperm nucleus, nuclear envelope breakdown, chromosome condensation, and reformation of nuclei. In this study, the ability of cell-free extracts to cause similar changes in zebrafish sperm was examined. When lysolecithin-treated sperm from zebrafish were incubated in Xenopus egg extracts, a series of changes in sperm nuclear morphology were observed periodically. These changes correlated with maturation-promoting factor (MPF) activity. Furthermore, sperm nuclei of zebrafish replicated DNA during reconstitution in Xenopus egg extracts. These results showed that cell-free extracts of Xenopus egg possess the ability to cause cell-cycle-dependent changes in zebrafish sperm, implying the possibility of generating transgenic zebrafish in a similar way to transgenic Xenopus.

Journal Article↗

PubMed1999

Zebrafish angiogenesis: a new model for drug screening.

Angiogenesis is necessary for tumor growth, making inhibition of vessel formation an excellent target for cancer therapy. Current assays for angiogenesis, however, are too complex to be practical for drug screening. Here, we demonstrate that the zebrafish is a viable whole animal model for screening small molecules that affect blood vessel formation. Blood vessel patterning is highly characteristic in the developing zebrafish embryo and the subintestinal vessels (SIVs) can be stained and visualized microscopically as a primary screen for compounds that affect angiogenesis. Small molecules added directly to the fish culture media diffuse into the embryo and induce observable, dose-dependent effects. To evaluate the zebrafish as a model, we used two angiogenesis inhibitors, SU5416 and TNP470, both of which have been tested in mammalian systems. Both compounds caused a reduction in vessel formation when introduced to zebrafish embryos prior to the onset of angiogenesis. Short duration (1 h) exposure of SU5416 was sufficient to block new angiogenic and vasculogenic vessel formation. In contrast, TNP470 required continuous exposure to block SIV formation and had no apparent effect on vasculogenic vessel formation. To ascertain whether blood vessels in the zebrafish embryo respond to angiogenic compounds, we introduced human VEGF into embryos. Injection of VEGF caused an observable increase in SIV formation.

Journal Article↗

PubMed2000

Identification of a functional transposase of the Tol2 element, an Ac-like element from the Japanese medaka fish, and its transposition in the zebrafish germ lineage.

The Tol2 element of the medaka fish Oryzias latipes belongs to the hAT family of transposons (hobo/Ac/Tam3). We report here identification of a functional transposase of Tol2 that is capable of catalyzing its transposition in the germ line of zebrafish Danio rerio. A transcript produced from Tol2 encodes a putative transposase. Zebrafish fertilized eggs were coinjected with mRNA transcribed in vitro, using cDNA of the Tol2 transcript as a template and a plasmid DNA harboring a mutant Tol2, which had a deletion in the putative transposase gene but retained necessary cis sequences. The injected fish were raised to adulthood and mated to noninjected fish, and genomic DNA of the progeny fish were analyzed by PCR and Southern hybridization. Half of F(1) fish obtained from one of eight injected fish contained the Tol2 DNA in their genomes but not the vector portion. Among these F(1) fish, Tol2 insertions at four different loci were identified, and some F(1) fish carried two or three different Tol2 insertions, indicating that the germ line of the founder fish is highly mosaic. Sequencing analyses revealed that, in all cases, Tol2 was surrounded by zebrafish genomic sequences, and an 8-bp duplication was created at the target site, indicating that Tol2 was integrated in the zebrafish genome through transposition. This study identifies an autonomous member of a DNA-based transposable element from a vertebrate genome. The Tol2 transposon system should thus be used to develop novel transgenesis and insertional mutagenesis methods in zebrafish and possibly in other fishes.

Animals↗

PubMed1994

SWIMMING METABOLISM OF WILD-TYPE AND CLONED ZEBRAFISH BRACHYDANIO RERIO

The availability of a gynogenetic isogenic homozygous diploid clonal strain (C) of the zebrafish (Brachydanio rerio), combined with the small adult body size of the species, made possible a study of the following two questions. (1) Is the genetic uniformity of a group of fish reflected in decreased variability of features of organismic performance physiology? (2) Is the metabolic cost of subcarangiform swimming significantly different in small fishes compared with large ones? Wild-type (WT) and C strain zebrafish maintained at 28 °C can all swim very rapidly [up to relative swimming speeds of 13 body lengths s-1 (BL s-1)] for extended periods (at least 2 h) without visibly tiring. Oxygen consumption rates were measured for both types at swimming speeds of 1.513 BL s-1. Whole-body lactate concentrations were also measured during routine activity and after prolonged exercise for both fish types. The slopes of the linear regressions between the logarithm of mass-specific oxygen consumption rates and relative swimming speeds for WT zebrafish were low (0.0100.024) and were not significantly different from zero. Regression slopes were also low (0.0090.026), but different from zero, for C zebrafish. Standard metabolic rates were 0.601.54 and 0.400.85 ml O2 g-1 h-1 for WT and C zebrafish respectively. Variances of slopes were significantly larger for WT than for C fish. Whole-body lactate concentrations and their variances were not significantly different between types and between rested and exercised fishes. The results demonstrate unusual swimming performance capacities, a remarkably low cost of swimming and some reductions in variability of C fish. Several possible explanations for the results are discussed.

Journal Article↗

PubMed1996

Specific teratogenic effects of different retinoic acid isomers and analogs in the developing anterior central nervous system of zebrafish.

Vertebrate embryos are sensitive to retinoic acid, either in deficiency or in excess. Although all-trans retinoic acid (RA) and 9-cis RA are known to have distinct but overlapping activities in higher organisms, only the all-trans isomer has been investigated in detail as a teratogen in zebrafish. We have identified profound and specific effects of 9-cis RA when administered to zebrafish embryos, and have confirmed the results of prior studies on the teratogenic effects of exogenous all-trans RA. Moreover, we have identified a 1-hr period during gastrulation in which embryos are particularly sensitive to the teratogenic effects of RA. In the course of these investigations, we have also studied the effects of two synthetic retinoids-a 9-cis RA analog, SR11217, and an all-trans RA analog, TTAB. An application of all-trans RA to the early zebrafish gastrula leads to defects that are limited to the caudal midbrain and rostral hindbrain. Our experiments show that an application of exogenous 9-cis RA for a period as short as 1 hr and at a concentration as low as 0.1 mu M can block differentiation of the rostral CNS. We have observed abnormal phenotypes using DIC optics, and have demonstrated further abnormalities using whole-mount immunocytochemical staining with antibodies to HNK-1 and acetylated alpha-tubulin. Major axon tract formation in the anterior CNS is unambiguously disrupted by the administration of 9-cis RA but not all-trans RA. Furthermore, exogenous 9-cis RA produces a qualitative alteration in the multiple-site expression pattern of the hlx-1 gene within the rostral CNS, while treatment with all-trans RA leads only to a weakened expression signal. The administration of TTAB and SR11217 result in distinctive inhibitions of hlx-1 expression. Unlike all-trans RA, which causes premature par-2 expression in the posterior midbrains of a majority of embryos, 9-cis RA leads to a complete deletion of this domain throughout development. These results suggest that 9-cis RA is a more active teratogen than all-trans RA in rostral CNS structures of the zebrafish embryo.

Animals↗

PubMed1998

Cloning of zebrafish vsx1: expression of a paired-like homeobox gene during CNS development.

vsx1 is a homeobox gene encoding a paired-type homeodomain and a CVC domain that was originally cloned from an adult goldfish retinal library. We previously reported the spatiotemporal expression pattern of vsx1 in the adult and developing retina of zebrafish and goldfish, and we suggested that vsx1 plays a role in determining the cell fate and maintenance of retinal interneurons. Other related genes encoding a CVC domain, such as vsx2 (alx) and chx10, are expressed both within and outside the retina during development. In this study, we report the cloning of zebrafish vsx1 and its developmental expression in both retinal and nonretinal regions of the CNS in zebrafish embryos. vsx1 expression was detected in a subset of hindbrain and spinal cord neurons before it was expressed in the retina. At about the same time that retinal expression began, the level of vsx1 was decreased in the spinal cord. The expression of vsx1 was progressively restricted, and eventually it was detected only in the inner nuclear layer (INL) of the developing retina. The combined expression patterns of teleost vsx1 and vsx2 (alx) during early zebrafish development encompasses the expression pattern observed for murine Chx10, and indicates a partitioning of function for CVC genes in lower vertebrates.

Amino Acid Sequence↗

PubMed2000

Genes dependent on zebrafish cyclops function identified by AFLP differential gene expression screen.

Zebrafish cyclops (cyc) encodes a Transforming Growth Factor beta (TGFbeta) signaling factor closely related to mouse Nodal. By comparing amplified fragment length polymorphisms (AFLP) from cyc mutant and wild-type cDNA pools, we devised a differential gene expression screen to isolate genes whose expression is dependent on Cyc signaling. We report two genes not previously described in the zebrafish that were identified using this approach. The first gene, crestin, is expressed predominantly in premigratory and migrating neural crest cells during somitogenesis stages. crestin expression is reduced in cyc mutants initially but recovers by late somitogenesis. The second gene encodes the zebrafish homologue of the calcium-binding protein, calreticulin. Zebrafish calreticulin is highly expressed in the hatching gland and in the floor plate, tissues that are affected in cyc mutants. During gastrulation, calreticulin transcripts are found in the dorsal mesendoderm, in the same cells that express the cyc gene. Expression is reduced in cyc mutants and is abolished by the one-eyed pinhead (oep) mutation that is presumed to prevent Nodal signaling. The identification of calreticulin suggests that a differential screen between wild-type and mutant cDNA is a useful approach to reveal regulation of unexpected gene expression in response to cellular signals. genesis 26:86-97, 2000.

Animals↗

PubMed2006

Calretinin immunoreactivity in the brain of the zebrafish, Danio rerio: distribution and comparison with some neuropeptides and neurotransmitter-synthesizing enzymes. I. Olfactory organ and forebrain.

The distribution of calretinin (CR) in the forebrain and the olfactory system of the adult zebrafish was studied by using immunocytochemical techniques. Previous studies in trout forebrain have indicated that CR-immunoreactive neurons acquire this phenotype rather early in development (Castro et al., J. Comp. Neurol. 467:254-269, 2003). Thus, precise knowledge of CR-expressing neuronal populations in adult zebrafish may help to decipher late stages of forebrain morphogenesis. For analysis of some forebrain nuclei and regions, CR distribution was compared with that of various ancillary markers: choline acetyltransferase, glutamic acid decarboxylase, tyrosine hydroxylase, neuropeptide Y, thyrotropin-releasing hormone, and galanin. The results reveal that calretinin is a specific marker of olfactory receptor neurons and of various neuronal populations distributed throughout the telencephalon and diencephalon. In addition, CR immunocytochemistry revealed characteristic patterns of fibers and neuropil in several telencephalic and diencephalic regions, indicating that it is a useful marker for characterizing a number of neural centers, pathways, and neuronal subpopulations in the zebrafish forebrain. Some ancillary markers also showed a distinctive distribution in pallial and subpallial regions, revealing additional aspects of forebrain organization. Comparison of the distribution of CR observed in the forebrain of zebrafish with that reported in other teleosts revealed a number of similarities and also some interesting differences. This indicates that various neuronal populations have maintained the CR phenotype in widely divergent teleost lines and suggests that CR studies may prove very useful for comparative analysis.

Animals↗

PubMed2006

Expression of pcp4a in subpopulations of CNS neurons in zebrafish.

The molecular organization of the zebrafish brain and its relation to neuroanatomical divisions are still largely unknown. In this study we have analyzed the expression of a small transcript encoding for the IQ containing polypeptide Pcp4a in developing and juvenile zebrafish. The transcript is exclusively expressed in neural structures with a pattern that is highly specific for restricted domains and cell populations throughout development, and it allows us to follow the development of these structures at different times. The expression of pcp4a characterizes the dorsocaudal telencephalon, dorsal habenula, pretectal nuclei, preglomerular complex, mammillary bodies, and deep layers of the optic tectum and is a hallmark of a subpopulation of reticulospinal neurons. In the telencephalon, comparison of the expression of pcp4a with other pallial markers showed a rostrocaudal gradient in the expression of these genes, which suggests that the dorsal telencephalon of zebrafish may be organized in distinct areas with different molecular natures. Pcp4 has been involved in modulating calcium signals and in binding to calmodulin, but its precise role in neuronal functions is not known. The analysis of pcp4a expression and localization in the zebrafish brain suggests that pcp4a may be a useful marker for sensory and some motor neuronal circuitries and for telencephalic areas processing sensory inputs.

Afferent Pathways↗