Biosynthesis and expression of ependymin homologous sequences in zebrafish brain

Sterrer, S.; Königstorfer, Andreas; Hoffman, William H.

doi:10.1016/0306-4522(90)90214-o

Cited by 25 publications

(1 citation statement)

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“…Although introns several kb in length are common in the Mhc genes in mammals (reviewed by Klein 1986), in all the fish Mhc genes studied so far, nearly all the introns are less than 1 kb long and most are less than 100 bp long. This difference between fish and mammals may not be limited to the Mhc genes (e. g., Muller-Schmid et al 1992;Hong and Schartl 1992;Huang et al 1992;Ber and Daniel 1992;Scott et al 1988;Sterrer et al 1990;Wilson et al 1991;Liu et al 1990;Chang et al 1991;Chiou et al 1990;…”

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confidence: 99%

Zebrafish Mhc class II ? chain-encoding genes: polymorphism, expression, and function

et al. 1993

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Its small size and short generation time renders the zebrafish (Brachydanio rerio) an ideal vertebrate for immunological research involving large populations. A prerequisite for this is the identification of the molecules critical for an immune response in this species. In earlier studies, we cloned the zebrafish genes coding for the beta chains of the class I and class II major histocompatibility complex (Mhc) molecules. Here, we describe the cloning of the zebrafish alpha chain-encoding class II gene, which represents the first identification of a class II A gene in teleost fishes. The gene, which is less than 3 kilobases (kb) distant from one of the beta chain-encoding genes, is approximately 1.2 kb long and consists of four exons interrupted by very short (< 200 base pairs) introns. Its organization is similar to that of the mammalian class II A genes, but its sequence differs greatly from the sequence of the latter (36% sequence similarity). Among the most conserved parts is the promoter region, which contains X, Y, and TATA boxes with high sequence similarity to the corresponding mammalian boxes. The observed striking conservation of the promoter region suggests that the regulatory system of the class II genes was established more than 400 million years ago and has, principally, remained the same ever since. Like the DMA, but unlike all other mammalian class II A genes, the zebrafish gene codes for two cysteine residues which might potentially be involved in the formation of a disulfide bond in the alpha 1 domain. The primary transcript of the gene is 1196 nucleotides long and contains 708 nucleotides of coding sequence. The gene is expressed in tissues with a high content of lymphoid/myeloid cells (spleen, pronephros, hepatopancreas, and intestine). The analyzed genomic and cDNA sequences are probably derived from different loci (their overall sequence similarity in the coding region is 73% and their 3' untranslated regions are highly divergent from each other). The genes are apparently functional. Comparison of genes from different zebrafish populations reveals high exon 2 variability concentrated in positions coding for the putative peptide-binding region. Phylogenetic analysis suggests that the zebrafish class II A genes stem from a different ancestor than the mammalian class II A genes and the recently cloned shark class II A gene.

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