R S Becker

Loyola University Chicago, Chicago, Illinois, United States

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Publications (6)50.77 Total impact

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    ABSTRACT: Previously, recombinations involving genes of the rabbit immunoglobulin heavy chain locus have been documented serologically. These data indicated that the sites at which the causative recombination events occurred could have been anywhere from within the VH gene cluster up to, or 3' of, C mu. Since these sites could not be localized further by serological methods, we attempted to do this using techniques of molecular biology. DNAs from homozygous recombinant rabbits and from the appropriate non-recombinant parental haplotypes were characterized using Southern blots hybridized with a panel of probes derived from cloned regions of the rabbit immunoglobulin heavy chain gene complex. In all three recombinants, the site was downstream of the entire VH cluster and upstream of the JH cluster within an approximately 50 kilobase (kb) region containing expanses of repetitive-sequence DNA as well as DH genes. DH-specific probes further showed that in two of the recombinants, the recombination appears to have occurred within or 5' of DH1 and 5' of DH2 genes; in the third it occurred 3' of the DH2 genes but at least approximately 5 kb 5' of the JH region.
    Immunogenetics 02/1991; 34(2):101-9. DOI:10.1007/BF00211422 · 2.23 Impact Factor
  • K. L. and Knight · R S Becker ·
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    ABSTRACT: Rabbits are unique in that their immunoglobulin VH regions bear allotypic markers encoded by allelic genes. The presence of these markers on most serum immunoglobulins is difficult to explain, as the germline contains several hundred VH genes. We cloned VH genes from normal rabbits of the VHa allotypes a1, a2, and a3 and from a mutant a2 rabbit, Alicia, which expresses almost no a2 allotype. The D-proximal VH gene VH1 of normal rabbits encoded prototype a1, a2, or a3 allotype VH regions in a1, a2, or a3 rabbits, respectively; VH1 was shown to be preferentially utilized in leukemic rabbit B cells. This VH1 gene was deleted from the germline of the Alicia rabbit. These data suggest that the allelic inheritance of a allotypes results from preferential utilization of VH1 in VDJ rearrangements. We suggest that antibody diversity in rabbit primarily results from somatic hypermutation and gene conversion.
    Cell 04/1990; 60(6):963-70. DOI:10.1016/0092-8674(90)90344-E · 32.24 Impact Factor
  • M Suter · R S Becker · K L Knight ·
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    ABSTRACT: VDJ genes were cloned from leukemic B cells of an a1/a2 heterozygous Emu-cmyc transgenic rabbit. Restriction mapping and nucleotide sequence analysis indicated that one clone, 5C3, had a VHa1-encoding gene segment functionally rearranged to a JH gene segment from the a2 chromosome. This VDJ gene may be the result of a trans recombination between a VH gene on the a1 chromosome and a JH gene segment on the a2 chromosome or, it may be the result of a cis recombination if the a2 chromosome contains VHa1-encoding gene segments.
    The Journal of Immunology 04/1990; 144(5):1997-2000. · 4.92 Impact Factor
  • R S Becker · S K Zhai · S J Currier · K L Knight ·
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    ABSTRACT: Overlapping cosmid clones of rabbit germ-line DNA containing VH, DH and JH gene segments were isolated. The map of this cluster of cosmid clones indicated that the rabbit VH and JH regions were separated by 63 kb. Hybridization of Southern blots of these cosmid clones with two different DH segment probes identified a total of six DH segments within the region between the VH and JH regions. The nucleotide sequences of the JH region and one of the DH segments have been determined. The DH segment has conserved heptamer and nonamer sequences separated by 12 and 11 bp at the 3' and 5' sides, respectively, of the coding region and hence, appears to be a functional gene. The nucleotide sequence of the JH region revealed four functional JH gene segments and one JH pseudogene. Inasmuch as the JH region had previously been linked by contiguous overlapping clones with C mu, C gamma, C epsilon, and one C alpha gene, this VH-DH-JH cluster and the clones containing the Ig H chain C region genes represent 190 kb of contiguous germ-line DNA of the Ig H chain locus.
    The Journal of Immunology 03/1989; 142(4):1351-5. · 4.92 Impact Factor
  • K L Knight · M Suter · R S Becker ·
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    ABSTRACT: A bovine recombinant phage library was constructed and screened with rabbit S mu and human C gamma probes. IgM, IgA, and IgE H chain constant region (CH) genes were isolated with the rabbit S mu probe and three IgG CH genes were isolated with the C gamma probe. The CH genes were individually cloned into an expression vector which contained a murine VDJ gene cloned from a hybridoma producing anti-dansyl hapten antibody. The resulting constructs were transfected into murine hybridoma cells producing L chain of the anti-dansyl antibody and stable transfectomas secreting chimeric bovine-murine IgA, IgE, or IgG subclass anti-dansyl antibodies were obtained. The chimeric antibodies, immunoprecipitated with Ag or with anti-bovine H chain antibodies, were analyzed by SDS-PAGE and were shown to contain H and L chains of expected size. Of the three chimeric antibodies derived from the C gamma genes, one reacted with anti-IgG1 antibody, another reacted with anti-IgG2 antibody and the third did not react with either anti-IgG1 or anti-IgG2. This third IgG appears to represent a "new" subclass of bovine IgG, IgG3. Southern blot analysis indicated that the bovine genome contains a fourth C gamma gene. These experiments demonstrate the usefulness of molecular genetic techniques for the isolation and characterization of Ig which are not readily purified from biologic fluids. These techniques will be useful for isolation and characterization of Ig genes from other outbred mammals.
    The Journal of Immunology 06/1988; 140(10):3654-9. · 4.92 Impact Factor
  • K L Knight · R S Becker ·
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    ABSTRACT: Bovine C mu, C gamma, C alpha and C epsilon genes were cloned in an EMBL4 recombinant phage library using rabbit immunoglobulin switch mu (Su) and human C gamma as probes. Restriction mapping and Southern blot analyses of these clones identified one clone which hybridized with rabbit C mu and JH probes. The HG and C mu regions were separated by 6 kb of DNA. One C alpha and one C epsilon gene were found on overlapping clones and were separated by approximately 15 kb of DNA. Southern blot analysis of germline DNA with a bovine C alpha associated probe (S alpha) indicated that the germline contains a single C alpha gene. Similar analyses with a bovine C epsilon probe indicated that the germline contains either one C epsilon gene with allelic restriction polymorphism or two C epsilon genes. Three C gamma genes were cloned and did not overlap with one another. Southern blot analyses of germline DNA with a bovine C gamma probe indicated that the germline contains a total of four C gamma genes. The genes cloned correspond to three of the four genes identified by Southern blot analysis. The orientation of each CH gene was assigned by hybridization with S mu or S gamma probes. The S gamma probe hybridized to DNA immediately adjacent to all three C genes; the S probe hybridized to DNA immediately adjacent to the C mu, C alpha and C epsilon genes. Unexpectedly, the S mu probe also hybridized with a segment of DNA approximately 7 kb downstream of the C mu gene. This may represent a switch region for C gamma.
    Veterinary Immunology and Immunopathology 01/1988; 17(1-4):17-24. DOI:10.1016/0165-2427(87)90123-1 · 1.54 Impact Factor

Publication Stats

260 Citations
50.77 Total Impact Points


  • 1990-1991
    • Loyola University Chicago
      • • Stritch School of Medicine
      • • Department of Microbiology and Immunology
      Chicago, Illinois, United States
  • 1988-1990
    • University of Illinois at Chicago
      • Department of Microbiology and Immunology (Chicago)
      Chicago, IL, United States