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J S States

Publications and source records attributed to J S States.

3 recordsLinked to original sources
PubMed1986

The major histocompatibility complex of tassel-eared squirrels. I. Genetic diversity associated with Kaibab squirrels.

The complexity and polymorphism of sequences related to the class I and class II genes of mammalian major histocompatibility complexes (MHCs) were investigated in the tassel-eared squirrel subspecies Sciurus aberti kaibabensis or Kaibab squirrel. Kaibab squirrels are geographically isolated on the Kaibab plateau north of the Grand Canyon in Arizona. Genomic DNA from 22 individuals was digested with Eco RI and Bam HI, electrophoresed, blotted, and hybridized with a panel of human class I and class II probes. Sequences homologous to DR alpha, DR beta, DQ beta probes were observed. A single, nonpolymorphic DR alpha-related sequence and multiple, polymorphic DQ alpha-related sequences were observed. Hybridization with DR beta and DQ beta probes revealed multiple, polymorphic sequences with such specificity that no bands were observed to hybridize with both probes. The level of polymorphism of beta sequences exceeded that observed with alpha sequences. Further, three Eco RI bands apparently included at least parts of both alpha and beta sequences. Hybridization of genomic blots with the HLA-B7 class I probe revealed a number of bands comparable in size range and number to other mammalian species. However, only a minor percentage of bands were observed to segregate. The inheritance of these five families of sequences appeared to be neither concordant nor random in the sample population. Based on prior conclusions in other species, these class I and class II sequences are presumed to map to the Kabib MHC, TLSA. Although DQ alpha- and DQ beta-related sequences were concordantly inherited, segregating sequences in the other families could not be assigned to identifiable, segregating haplotypes. These observations suggest that the present-day TSLA haplotypes have been derived from a limited number of progenitor haplotypes through repeated, intra-TSLA recombination.

Animals↗
PubMed1986

The major histocompatibility complex of tassel-eared squirrels. II. Genetic diversity associated with Abert squirrels.

The extent of polymorphism and the rate of divergence of class I and class II sequences mapping to the mammalian major histocompatibility complex (MHC) have been the subject of experimentation and speculation. To provide further insight into the evolution of the MHC we have initiated the analysis of two geographically isolated subspecies of tassel-eared squirrels. In the preceding communication we described the number and polymorphism of TSLA class I and class II sequences in Kaibab squirrels (S. aberti kaibabensis), which live north of the Grand Canyon. In this report we present a parallel analysis of Abert squirrels (S. aberti aberti), which live south of the Grand Canyon in northern Arizona. Genomic DNA from 12 Abert squirrels was digested with restriction enzymes, electrophoresed, blotted, and hybridized with DR alpha, DR beta, DQ alpha, DQ beta, and HLA-B7 probes. The results of these hybridizations were remarkably similar to those obtained in Kaibab squirrels. The majority of class I and class II bands were identical in size and number, suggesting that Abert and Kaibab squirrels have not significantly diverged in the TSLA complex despite their geographical separation. Relative polymorphism of class II sequences was similar to that observed with Kaibab squirrels: beta sequences exhibited higher polymorphism than alpha sequences. As in Kaibab squirrels, a number of alpha and beta sequences were apparently carried on the same fragments. In comparison to class II beta sequences, there was limited polymorphism in class I sequences, although a diverse number of class I genotypes were observed. Attempts to identify segregating TSLA haplotypes were futile in that the only families of sequences with concordant distributions were DQ alpha and DQ beta. These observations and those obtained with Kaibab squirrels suggest that the present-day TSLA haplotypes of both subspecies are derived from a limited number of common, progenitor haplotypes through repeated intra-TSLA recombination.

Animals↗