Complete nucleotide sequence of an immunoglobulin heavy-chain gene and analysis of immunoglobulin gene organization in a primitive teleost species.
The immunoglobulin heavy-chain variable region (VH) locus in a phylogenetically primitive teleost (Elops saurus) has been characterized by a strategy that relied initially on cross-hybridization between genomic VH segments and a murine VH probe. Using a homologous (Elops) VH probe and DNA sequencing, this gene family has been shown to be complex and to contain overt pseudogenes. A homologous probe also has been used to isolate a full copy length cDNA containing constant (CH) as well as joining (JH) and VH regions. Genomic analyses using CH-, JH-, and VH-specific probes have demonstrated the presence of only a single hybridizing CH and several JH elements. JH-CH linkage is less than or equal to 3.6 kilobases (kb) and VH-CH linkage is less than or equal to 100 kb, as estimated by field-inversion gel electrophoresis. An additional VH family sharing less than 50% nucleotide identity with the prototype Elops VH sequence is described. Taken together, these results suggest that the immunoglobulin VH locus in a comparatively primitive teleost resembles the VH locus in mammals, but not that found in the more phylogenetically distant elasmobranchs. The evolutionary radiations of cartilaginous and bony fishes are associated with a dramatic change in the organization and, presumably, regulation of immunoglobulin genes. The origins of the modern VH gene locus can be traced to the primitive teleost fishes.
Amemiya
C T
CT
Laboratory of Molecular Genetics, Tampa Bay Research Institute, Saint Petersburg, FL 33716.
Litman
G W
GW
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D005399:Fishes / Q000276:immunology*; D005803:Genes, Immunoglobulin; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D015345:Oligonucleotide Probes; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid
D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region; D015345:Oligonucleotide Probes