ABSTRACT
We have identified cDNAs encoding a second zebrafish ortholog of the human Na,K-ATPase beta 2 subunit. The beta 2b cDNA encodes a 292 amino acid-long polypeptide with 74% identity to the previously characterized zebrafish beta 2a subunit. By using a zebrafish meiotic mapping panel, we determined that the beta 2b gene (atp1b2b) was tightly linked to markers on linkage group 5, whereas the beta 2a gene was located on linkage group 23. In situ hybridization analysis shows that in developing zebrafish embryos, atp1b2a and atp1b2b are predominantly expressed in the nervous system. beta 2a transcripts were abundantly expressed throughout brain as well as spinal cord neurons and lateral line ganglia. In contrast, beta 2b mRNA expression was primarily detected in sensory organs, including retina, otic vesicles, and lateral line neuromast cells. These results suggest that the beta 2a and beta 2b genes play distinct roles in developing brain and sensory organs, and raise the possibility that the functions encoded by the single mammalian beta 2 gene may be partitioned between the two zebrafish beta 2 orthologs.
Subject(s)
Central Nervous System/embryology , Gene Expression Regulation, Developmental , Isoenzymes/biosynthesis , Nerve Tissue Proteins/biosynthesis , Sense Organs/embryology , Sodium-Potassium-Exchanging ATPase/biosynthesis , Zebrafish/embryology , Animals , Central Nervous System/enzymology , Chromosome Mapping , DNA, Complementary/genetics , Embryo, Nonmammalian/metabolism , Embryo, Nonmammalian/ultrastructure , Evolution, Molecular , Ganglia, Sensory/embryology , Ganglia, Sensory/enzymology , Genes , Genetic Linkage , In Situ Hybridization , Isoenzymes/genetics , Isoenzymes/physiology , Molecular Sequence Data , Morphogenesis , Nerve Tissue Proteins/genetics , Nerve Tissue Proteins/physiology , Neurons/enzymology , Organ Specificity , Protein Subunits , RNA, Messenger/biosynthesis , Sense Organs/enzymology , Sodium-Potassium-Exchanging ATPase/genetics , Sodium-Potassium-Exchanging ATPase/physiology , Zebrafish/genetics , Zebrafish/metabolismABSTRACT
We have identified and characterized cDNAs encoding a novel zebrafish Na,K-ATPase alpha subunit. The full-length cDNA encodes a 1,023-amino-acid-long peptide which shows greatest homology to zebrafish alpha1 polypeptides. Radiation hybrid mapping localized the new gene (atp1a1a.5) to linkage group 1 in close proximity to the previously identified cluster of Na,K-ATPase alpha1 genes. The expression of atp1a1a.5 in zebrafish embryos was analyzed using whole-mount in situ hybridization. From mid-somitogenesis through 48 h post fertilization (hpf), atp1a1a.5 transcripts were detected in the pronephric duct, ear, and mucous cells. This expression pattern continues through 108 hpf, when high levels of expression were also detected in the intestinal bulb.
Subject(s)
Chromosome Mapping , Gene Expression Profiling , Sodium-Potassium-Exchanging ATPase/genetics , Zebrafish/genetics , Animals , Kidney/embryology , Kidney/metabolism , Organ Specificity , Zebrafish/embryology , Zebrafish ProteinsABSTRACT
We have identified and characterized cDNAs encoding a novel zebrafish Na,K-ATPase alpha subunit. The full-length cDNA encodes a 1023-amino-acid-long peptide which shows greatest homology to zebrafish alpha1 polypeptides. Radiation hybrid mapping localized the new gene (atp1a1a.5) to linkage group 1 in close proximity to the previously identified cluster of Na,K-ATPase alpha1 genes. The expression of atp1a1a.5 in zebrafish embryos was analyzed using whole-mount in situ hybridization. From mid-somitogenesis through 48 h post fertilization (hpf), atp1a1a.5 transcripts were detected in the pronephric duct, ear, and mucous cells. This expression pattern continues through 108 hpf, when high levels of expression were also detected in the intestinal bulb.
