Using the structurally defined protein antigen cytochrome C, studies were conducted in an attempt to delineate the fine specificities of channel catfish immune repertoires. We have previously reported that species variants of cytochrome C were cross-stimulatory to peripheral blood leukocytes (PBL) from catfish immunized with the pigeon variant. Molecular database analyses revealed the existence of overlapping epitopes that appear to define the specificity of the immune response to a "family" of closely related antigens. To further explore these observations, studies were conducted to determine the contribution of peptide 81-104 to the immunogenicity of cytochrome C. Current data showed that peptide 81-104 and intact cytochrome C were stimulatory to PBL from fish previously immunized with the native molecule. In contrast, PBL from fish previously primed with the peptide 81-104 responded only to the immunizing peptide as well as to some, but not all, variants of the peptide 81-104. The differences in the stimulatory capacities of the peptide variants appeared to correlate with amino acid substitutions at various positions of the peptide and changes in their predicted secondary structures.

Amino Acid Sequence↗

PubMedDate not supplied

The immunoglobulin genes of fish.

Explore the source record for details and available documents.

Animals↗

PubMedDate not supplied

cDNA sequences and organization of IgM heavy chain genes in two holostean fish.

Immunoglobulin M heavy chain (mu) sequences of two holostean fish, the bowfin, Amia calva, and the longnose gar, Lepisosteus osseus, were amplified from spleen mRNA by RACE-PCR, cloned, and sequenced. Each mu chain showed the conserved four constant domain structure typical of a secreted mu chain. Southern blot analyses with specific heavy chain variable (VH) and constant (CH) region probes suggest that both fish possess an IgH locus that resembles that of the teleosts, amphibians, and mammals in its organization. The overall sequence similarity of gar and bowfin mu chains was 60% and 48% at the nucleotide and amino acid levels, respectively, while similarity to the mu chains of teleosts and elasmobranchs was lower. The bowfin mu chain possesses a distinctive proline-rich sequence at the C mu 1/C mu 2 boundary; a shorter proline-rich sequence is present at this position in the gar mu chain. Both gar and bowfin show, in their C mu 4 sequences, motifs that could serve as cryptic splice donor sites for the production of mRNA encoding the membrane-bound form of the mu chains, and the bowfin also shows a potential cryptic splice donor site in the C mu 3 exon.

Amino Acid Sequence↗

PubMedDate not supplied

Alternate pre-mRNA processing pathways in the production of membrane IgM heavy chains in holostean fish.

A single gene encodes two forms of the IgM heavy chain (mu) in vertebrates: one (microseconds) present in serum as secreted IgM and the other (microns) as the antigen receptor form of IgM present on the B-lymphocyte membrane. The mRNAs encoding microseconds and microns are derived from a single primary transcript by alternate pathways of RNA processing. In all vertebrates so far examined, with the exception of teleosts, microns mRNA is produced by splicing the transmembrane (TM) encoding exon 1 into a cryptic donor site near the 3' end of the C mu 4 exon. In contrast, teleost species splice the TM exon 1 into the regular splice donor site at the 3' boundary of the C mu 3 exon. We have examined micron mRNAs in two species of primitive bony fish, the holostean bowfin and the longnose gar. These fish utilize both the C mu 3 to TM1 (teleost) pathway and the typical cryptic C mu 4 to TM1 pathway. In addition the bowfin possesses a cryptic splice donor site near the middle of C mu 3. This is used in the production of a third species of microns-encoding mRNA, but does not participate in the production of an alternate form of the microseconds mRNA. The structure and patterns of expression of their mu genes suggest that the gar and bowfin may be more closely related than implied by the current view of fish evolution.

Alternative Splicing↗

PubMedDate not supplied

Immunoglobulin VH genes of the goldfish, Carassius auratus: a re-examination.

Five VH-related genomic sequences from the goldfish, Carassius auratus, have been characterized. One of these sequences appeared to be a functional gene, and four to be pseudogenes. The main conclusions drawn from this study were that: (1) With minor exceptions, goldfish VH genes conform to the typical pattern of vertebrate VH genes in terms of their structure (they encode an intron-split hydrophobic leader, 3 framework and 2 complementarity-determining regions, and possess a typical 3' recombination signal sequence for VH to D joining) and regulatory sequences (possession of a typical upstream octameric promoter). (2) The sequences indicate that goldfish possess multiple families of VH sequences (at least three). Two of these families contain approximately 6 and 10 members, as judged from Southern blot hybridization experiments. (3) Goldfish VH gene families are distributed throughout the members of the species in the manner typical of that of VH families in other vertebrate species. Thus, this observation corrects the previous conclusion (Wilson et al., Proc. natn. Acad. Sci. U.S.A. 85, 1566-1570, 1988) that VH genes are discontinuously distributed in the goldfish population.

Animals↗

PubMedDate not supplied

Telomerase expression and telomere length in immortal leukocyte lines from channel catfish.

Normal channel catfish leukocytes readily undergo spontaneous in vitro immortalization yielding functionally active diploid cell lines. Since telomerase activation appears to be a critical step in the establishment of immortal mammalian cells, studies were undertaken to determine if and when telomerase expression occurs during the in vitro immortalization process of channel catfish leukocytes. To this end, freshly isolated peripheral blood leukocytes (PBL) from normal fish were shown to exhibit low to undetectable levels of telomerase activity and within four days after culture initiation showed dramatic increases in telomerase activity which typically remained high for at least four weeks. This activity then declined, concomitant with decreases in cellular proliferation and increases in cell death. Cells which escaped this culture "crisis" re-expressed high levels of telomerase activity indefinitely. Although telomerase activity was expressed early in the immortalization process, clonal cell lines derived from these cultures had relatively short telomeres. These results suggest that telomerase expression in catfish leukocytes is activation-induced, and its expression does not necessarily stabilize telomere length until a critically, albeit ill-defined, short length is reached.

Animals↗

PubMedDate not supplied

Diversity of the immunoglobulin heavy chain in the Atlantic salmon (Salmo salar L.) is contributed by genes from two parallel IgH isoloci.

Immunoglobulin heavy chain (IgH) variable (V) region cDNAs from the Atlantic salmon, Salmo salar L., have been isolated and analysed with respect to diversity and transcription of the two parallel IgH isoloci in this species. A total of nine V(H) families were defined according to the 80% identity criterion, of which seven were highly related (>80% identity) to the V(H) families defined in rainbow trout and arctic charr. The variability of the CDR1 and 2 was low, although mutational hot-spot consensus sequences were accumulated in these regions. The CDR3 showed largest variability, expressing at least eight different groups of D motifs diversified by fusion of the D motifs, possible N and P nucleotide insertions and exonuclease activity. Presumably functional transcripts expressing D motifs in all three reading frames were identified for two of the motifs. The cDNAs were mapped to either of the two parallel loci, and sequence analysis revealed that the repertoire of V(H) segments was contributed by transcription of genes from both of the IgH isoloci. Transcription of genes from both isoloci generated no obvious effects on variability in the CDR3 of the Atlantic salmon IgH chains, although one additional J(H)-segment with altered N-terminal was generated by the process of duplication and divergence. Thus, the issue of biological significance of the two IgH isoloci remains unclear.

Amino Acid Sequence↗

PubMedDate not supplied

cDNA sequence and organization of the immunoglobulin light chain gene of the duck, Anas platyrhynchos.

A cDNA was cloned which encoded an immunoglobulin (Ig) light (L) chain of the White Pekin duck. The organization of the variable (V) and constant (C) domains was analyzed by genomic Southern blotting. The duck L chain gene has a similar chromosomal organization to that of the chicken, with a single lambda-like C region and multiple VL, hybridizing elements. The amino acid sequence of the VL region of the White Pekin duck L chain showed 88% identity with the Muscovy duck and 87% identity with the chicken, the JL region showed 92% identity with these species, and the CL region showed 88% identity with Muscovy duck and 66% with chicken. The constraints imposed by the gene-conversion mechanism of generating antibody diversity might account for the similarities of the avian V region sequences.

Amino Acid Sequence↗

PubMedDate not supplied

Membrane immunoglobulin-associated molecules on channel catfish B lymphocytes.

Membrane immunoglobulin (mIgM) on the surface of channel catfish B lymphocytes is non-covalently associated with 64 and 70 kDa molecules which are composed of covalent 32 kDa dimers and covalent 45/25 kDa subunits, respectively. Cross-linking of mIgM on catfish B cells leads to rapid phosphorylation of tyrosine residues in these presumed accessory as well as numerous other cytoplasmic molecules. These data indicate that fish likely use a signal transduction system containing elements similar to those of mammalian B cells.

Animals↗

PubMedDate not supplied

Coding sequences of the MHC II beta chain of homozygous rainbow trout (Oncorhynchus mykiss).

Six lines of homozygous rainbow trout (Oncorhynchus mikiss) from different genetic and geographical backgrounds have been produced as aquatic models for biomedical research by the chromosome set manipulation techniques of androgenesis and gynogenesis. Messenger RNA from spleens was extracted. and the MHC II B cDNA sequences, amplified by RT PCR, were cloned into plasmids. Sequences of the MHC II beta2 domains were highly conserved between the different plasmids from the same and different lines of trout. Most of the variability among sequences was found in the amino terminal half of the beta1 domain, which corresponds with the peptide binding region of the MHC II molecule. This diversity suggests that the different lines of trout may exhibit differences in immune response. Rainbow trout MHC II B sequences were similar to the MHC II B sequences of the Pacific salmon (O. gorbuscha, O. tshawytscha, O. nerka, O. miasou, O. kisutch). Southern blot analysis performed on the restricted DNA of the OSU and Hot Creek trout, and the doubled haploid progeny produced by androgenesis from OSU x Hot Creek hybrids indicates that two distinct genes encode the MHC II B sequences and that these genes are unlinked.

Amino Acid Sequence↗

PubMedDate not supplied

An additional family of VH sequences in the channel catfish.

A heavy chain variable region cDNA sequence of the channel catfish (Ictalurus punctatus) prototypical for a new VH family (approximately 20 or more members) is presented. The nucleotide and inferred amino acid sequences differ by 32-52% and 41-68%, respectively, from those for the already described catfish VH families.

Amino Acid Sequence↗