Critical roles of DNase1l3l in lens nuclear degeneration in zebrafish.

The vertebrate lens undergoes organelle and nuclear degradation during lens development, allowing the lens to become transparent. DNase2b is an enzyme responsible for nuclear degradation in the mouse lens; however, dnase2b expression in zebrafish showed a distribution pattern that differed from that in mice. No zebrafish dnase2b was detected by reverse-transcription polymerase chain reaction until around 120 h postfertilization (hpf), suggesting that dnase2b is not expressed in the critical period for lens nuclear degradation, which corresponds to 56-74 hpf.

CD73, a novel cell surface antigen that characterizes retinal photoreceptor precursor cells.

Purpose: The authors sought to identify cell surface markers of photoreceptor and its precursor cells.

Methods: The expression of surface CD antigens that label both temporally and spatially distinct populations of mouse retinal cells were examined. Of the antibodies that showed positive signals in retinal cells, CD73 was focused on for more detailed analyses.

Forkhead transcription factor foxe1 regulates chondrogenesis in zebrafish.

Forkhead transcription factor (Fox) e1 is a causative gene for Bamforth-Lazarus syndrome, which is characterized by hypothyroidism and cleft palate. Applying degenerate polymerase chain reaction using primers specific for the conserved forkhead domain, we identified zebrafish foxe1 (foxe1). Foxe1 is expressed in the thyroid, pharynx, and pharyngeal skeleton during development; strongly expressed in the gill and weakly expressed in the brain, eye, and heart in adult zebrafish.

CD138/syndecan-1 and SSEA-1 mark distinct populations of developing ciliary epithelium that are regulated differentially by Wnt signal.

Ciliary epithelium (CE), which consists of nonpigmented and pigmented layers, develops from the optic vesicle. However, the molecular mechanisms underlying CE development have not been closely examined, in part because cell-surface markers suitable for specific labeling of subregions of the retina were unknown. Here, we identified CD138/syndecan-1 and stage specific embryonic antigen-1 (SSEA-1) CD15 as cell-surface antigens marking nonpigmented and pigmented CE, respectively.

Transcriptional repressor foxl1 regulates central nervous system development by suppressing shh expression in zebra fish.

We identified zebra fish forkhead transcription factor l1 (zfoxl1) as a gene strongly expressed in neural tissues such as midbrain, hindbrain, and the otic vesicle at the early embryonic stage. Loss of the function of zfoxl1 effected by morpholino antisense oligonucleotide resulted in defects in midbrain and eye development, and in that of formation of the pectoral fins. Interestingly, ectopic expression of shh in the midbrain and elevated pax2a expression in the optic stalk were observed in foxl1 MO-injected embryos.

Zebrafish Numb homologue: phylogenetic evolution and involvement in regulation of left-right asymmetry.

Numb and its homologue, Numb-like (Numbl), play important roles in mammalian development, but their role in embryonic development of lower vertebrates remains unknown. We cloned a zebrafish numb homologue (znumb) by searching database. znumb shows approximately 60% identity with mammalian Numb orthologs.

SSEA-1 marks regionally restricted immature subpopulations of embryonic retinal progenitor cells that are regulated by the Wnt signaling pathway.

Identification and expansion of retinal progenitor cells are critical issues from both scientific and clinical aspects. Here, we identified SSEA-1 (CD15) as a novel surface antigen that can be used to define immature retinal progenitor cells. SSEA-1-expressing retinal cells were found in the peripheral region of the early embryonic mouse retina, and then their number dramatically disappeared along with retinal development.

Negative regulation of retinal-neurite extension by beta-catenin signaling pathway.

Although there have been many studies on the regulation of neurite extension in mouse brain, such a mechanism in neural retina has remained to be clarified. To delineate the role of Wnt signaling in retinal development, we used a retrovirus-vector-mediated expression system to express various mutants forms of Wnt signaling members in E17.5 mouse retinal explant cultures, which are an excellent system to examine retinal development in vitro.

Cooperative interaction of Angiopoietin-like proteins 1 and 2 in zebrafish vascular development.

Angiopoietin-like protein (Angptl) 1 and Angptl2, which are considered orphan ligands, are highly homologous, particularly in the fibrinogen-like domain containing the putative receptor binding site. This similarity suggests potentially cooperative functions between the two proteins. In this report, the function of Angptl1 and Angptl2 is analyzed by using morpholino antisense technology in zebrafish.

Melk-like kinase plays a role in hematopoiesis in the zebra fish.

A serine/threonine kinase, Melk, was initially cloned in mouse oocytes as a maternal gene, but whose function was unknown. In adult mice, Melk was strongly expressed in the thymus and bone marrow, suggesting a role for Melk in hematopoiesis. We cloned a Melk-like gene from zebra fish (zMelk).

Isolation and expression patterns of genes for three angiopoietin-like proteins, Angptl1, 2 and 6 in zebrafish.

Angiopoietin-like proteins (Angptls) are known to possess biological activities not only in the vascular system, but in the other mammalian tissues; however, their expression patterns and function in embryogenesis have not been extensively characterized. Here, we identify three zebrafish genes (Zangptl1, Zangptl2 and Zangptl6) highly homologous to mammalian Angptl1/ARP1, Angptl2/ARP2 and Angptl6/AGF, and describe their adult and embryonic temporal and spatial expression patterns. Zangptl1 is expressed faintly in the somites, while Zangptl2 is first detected in the yolk sac extension, spinal cord and branchial arches and is later expressed in the liver primordium and pectoral fin buds.

Identification and characterization of Veph, a novel gene encoding a PH domain-containing protein expressed in the developing central nervous system of vertebrates.

We isolated Veph, a novel gene encoding a pleckstrin homology (PH) domain-containing protein from a mouse. Veph was strongly expressed in the embryonic brain, and its expression level gradually decreased in later stages. In situ hybridization analysis of sectioned embryo brains revealed that Veph was expressed exclusively in the ventricular zone.

Specification of the retinal fate of mouse embryonic stem cells by ectopic expression of Rx/rax, a homeobox gene.

With the goal of generating retinal cells from mouse embryonic stem (ES) cells by exogenous gene transfer, we introduced the Rx/rax transcription factor, which is expressed in immature retinal cells, into feeder-free mouse ES cells (CCE). CCE cells expressing Rx/rax as well as enhanced green fluorescent protein (CCE-RX/E cells) proliferated and remained in the undifferentiated state in the presence of leukemia inhibitory factor, as did parental ES cells. We made use of mouse embryo retinal explant cultures to address the differentiation ability of grafted ES cells.

A novel smoothelin-like, actin-binding protein required for choroidal fissure closure in zebrafish.

A gene expressed in the choroidal fissure of the zebrafish eye was isolated. This gene, designated #61, contained significant homology with the previously reported actin-binding protein smoothelin. During zebrafish embryogenesis, #61 expression was first detected in the lateral mesoderm of the mid-trunk region, and then strong expression was observed in the choroid fissure of the eye and in a part of the brain at 30 hpf.