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M R Wilson

Publications and source records attributed to M R Wilson.

245 records · Page 14Linked to original sources
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

MHC class II A genes in the channel catfish (Ictalurus punctatus).

In order to characterize the Major histocompatibility complex (MHC) class II A genes of the channel catfish (Ictalurus punctatus) a cDNA library was screened and PCR was performed. Four different full-length cDNA sequences for MHC class II A genes were obtained from a clonal B cell line derived from an outbred fish. Two different genomic sequences and corresponding cDNAs were obtained from a presumably homozygous gynogenetic catfish. The A genes have five exons and four phase one introns. The first exon encodes the 5' untranslated region (UTR) and leader peptide; the second and third exons encode the alpha1 and alpha2 domains, respectively. The connecting peptide, transmembrane and cytoplasmic domains, as well as part of the 3' UTR, are encoded by the fourth exon and the rest of the 3' UTR is encoded by the fifth exon. Southern blot analyses using an exon three probe revealed two to four hybridizing fragments with considerable restriction fragment length polymorphisms evident among randomly selected outbred channel catfish. These findings are consistent with the presence of at least two functional polymorphic MHC class II A gene loci. An unusual aspect of the channel catfish MHC class II alpha chain is its lack of N-linked glycosylation sites.

Amino Acid Sequence↗
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

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

MHC class II B genes in the channel catfish (Ictalurus punctatus).

Two different cDNA sequences for major histocompatibility complex (MHC) class II beta chains from the channel catfish (Ictalurus punctatus) have been identified. Homology between these sequences and those previously identified as MHC class II B genes in other teleosts suggests they represent alleles of the DAB locus. The inferred amino acid sequences show strong evidence for a functional polypeptide chain with a peptide binding region. Southern blot analysis reveals polymorphism in the MHC class II B gene(s) of the channel catfish and suggests the presence of two to four genes.

Amino Acid Sequence↗
PubMedDate not supplied

Evidence for Jak-STAT interaction in channel catfish lymphoid cells.

Herein is described the identification of a putative Jak molecule in the channel catfish. A commercially available polyclonal antibody against human Jak1 was shown to react in Western blot analyses with molecules of approximately 140, 80, and 60 kDa from cell lysates of catfish long-term lymphoid cell lines. It is postulated that the 140 kDa protein is a catfish Jak homolog and the 80 and 60 kDa proteins may represent breakdown products of the 140 kDa protein. Both the 140 and 60 kDa proteins appear to be constitutively tyrosine phosphorylated in channel catfish long-term leukocyte lines. Furthermore, immuno-precipitation studies indicate an association between the Jak molecule and a STAT molecule in cloned T cell lines, and to a much lesser extent in cloned B cell lines, indicative of a possible autocrine stimulatory pathway in catfish long-term T cell lines.

Animals↗
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↗
PubMedDate not supplied

Prevalence of Sm antibody in family members of Sm positive patients with systemic lupus erythematosus.

Sm antibody is found almost exclusively in systemic lupus erythematosus (SLE). Considering Sm antibody to be a possible "marker" for SLE, we investigated the prevalence of Sm antibody in 29 first degree relatives and spouses of Sm positive patients with SLE. Sm antibody was not detected by Ouchterlony agar gel diffusion in any of the study group, and none of the family members or spouses had SLE or other antoimmune disease. This study suggests that Sm antibody is not a likely "marker" for a transmissable agent involved in the pathogenesis of SLE.

Adult↗