Linked genetic markers of the rabbit κ light chain are not linked to the Tcr β chain genes

In order to investigate linkage, we used serum allotypes of the two rabbit C isotypes and restriction fragment length polymorphisms (RFLPs) of the genes for V , C , and T-cell receptor C . The inheritance of these genetic markers was studied through backcross and F₂ matings. Southern analysis and hybridization of genomic DNA with a C probe detected a 5 kb Pst I fragment linked to expression of the K2bas1 allotype and the presence of the 1b ^bas gene and a 6.6 kb Pst I fragment linked to the expression of the K1b9 allotype, the presence of the 2 ^bas2 gene and lack of expression of the K2bas1 allotype. A V probe detected a 1.3 kb Eco RI fragment linked to the presence of the 1b ^bas gene and expression of the K2bas1 allotype. In contrast, the 9 or 14 kb Eco RI RFLP (C ^a or C ^b) detected with a Tcr chain probe segregated independently from C allotypes and RFLPs. It has previously been found that C and C are also unlinked in man, whereas in the mouse they are linked at a distance of 8 centimorgans.     

Human polyreactive and monoreactive antibodies: effect of glycosylation antigen binding

The present experiments were initiated to determine whetherthe carbohydrate portions of antibody molecules contribute topolyreactivity. Cell lines making human monoclonal polyreactiveor monoreactive antibodies of the immunoglobulin (Ig) M, IgGand IgA isotypes were treated with tunicamycin to block N-linkedglycosylation of the proteins. Analysis of the secreted nativeand non-glycosylated proteins revealed a >95% inhibitionof [³H]mannose incorporation. Electrophoresis on sodium dodecylsulphate-polyacrylamide gels of the proteins from tunicamycin-treatedcells showed increased mobility and the absence of [³H]mannoseincorporation of the immunoglobulin heavy chains, consistentwith the lack of glycosylation. The native and non-glycosylatedantibodies were then tested for their ability to bind differentantigens. Despite the lack of glycosylation, both polyreactiveand monoreactive antibodies bound to antigens with little ifany loss of reactivity or specificity. It is concluded thatthe carbohydrate moieties do not contribute significantly topolyreactivity. antigen binding glycosylation polyreactive antibodies     

Genomic sequence and organization of rabbitTcrb constant region genes

We previously reported that some rabbits have three different copies of T-cell receptor b (Tcrb) constant region genes unlike man, mice, and rats who generally have two copies. Two of theseCß genes were found on an ≈ 14 kilobase (kb) and one on an ≈ 6 kbEco RI fragment. The gene on the 6 kb fragment is of ß2 type. A previously described portion of the 14 kb fragment appeared to have sequences characteristic ofCß1. We have now shown that the 6 kb fragment is adjacent to and 3′ of the 14 kb fragment. Furthermore, the second linked sequence ofCß gene present on the 14 kb fragment resembles to a large extent theCß2 gene present on the 6 kb fragment. Moreover, this secondCß gene has a 5′ cluster ofJß sequences resemblingJß2 of other species. However, exon 4 and the 3′ unranslated region (3′UT) are of the ß1 type. Mapping studies using southern analyses of both genomic DNA and the 14 kb clone have identified another cluster ofJß2 sequences 5′ of the third tandemCß2 gene present on the 6 kbEco RI fragment. Thus, the second gene on the 14 kb fragment appears to be a chimeric genomicTcrb gene that may have arisen by an unequal crossing-over event analogous to that which may have deletedCß1,Dß2, andJß2 in NZW mice.