Article

Cytological Identification of the Chromosome Carrying the IXth Linkage Group (Including H-2) in the House Mouse

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Abstract

Mus poschiavinus x M. musculus hybrids, which had seven metacentric chromosomes derived from the poschiavinus complement, were repeatedly backcrossed to M. musculus and selected for the chromosome carrying the H-2 complex. A line called T1/Klj was established which had one metacentric chromosome. It was shown by linkage tests and by cytogenetic studies that one arm of this metacentric chromosome corresponds to the M. musculus acrocentric chromosome carrying linkage group IX, in which the H-2 complex is found. The distance from the H-2 locus to the centromere was tentatively estimated as 14 map units.

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... musculus in that 14 pairs of telocentric chromosomes have been replaced by seven pairs of biarmed chromosomes (GROPP, TETTENBORN and LBONARD 1970). One of these seven chromosomes carries the H-2 locus (KLEIN 1971 ) . Klein produced a line carrying this as the only biarmed chromosome in the karyotype by three generations of backcrossing M . ...
Article
Polymorphism of Giemsa-specific centromeric heterochromatin (C.H.) has been described in the laboratory and wild mice. All examined wild mice and inbred mouse strains display some chromosomes with considerably reduced or enlarged C.H. regions. The quantity of C.H. could be an inherent property of a chromosome as inferred from (a) the finding of the identical C.H. pattern within inbred strains, (b) the finding that two genetically related inbred strains, C3H and CBA, separated from each other for more than 150 generations, possess the same two chromosome pairs with tiny C.H. marker regions. These chromosomes were identified as No. 1 (l.g. XIII) and No. 14 (l.g.III) by means of T(14;15)6Ca translocation, and C- and G-band analysis. The neutrality of C.H. polymorphism in murine genome is inferred from the heterozygosity for the C.H. variants found in all studied wild mice. The possible relationship of C.H. polymorphism to the centromere interference phenomenon is hypothesized.
Article
Linkage relationships of three gene markers of chromosome 17, namely Brachyury (T), tufted (tf), and Histocompatibility-2 (H-2), to the break-point of T(16; 17)43H male sterile translocation were established. The following order was found: T−tf−T43H−H-2. In all cases the translocation break was found in cis to H-2k, haplotype, no recombinant being found among 218 backcross individuals examined. More than 60 viable and fertile animals trisomic for the proximal part of chromosome 17 (including T-t genetic complex) have been recovered among progeny of T43H/+ female translocation heterozygotes as a result of adjacent −2 disjunction at first meiotic division. Mutation tf has been assigned to band 17B in chromosome 17 by comparing the location of T190Ca and T43H genetic and cytological breakpoints. Recombination between centromere 17 and T43H break was reduced almost to zero in the presence of Rb(16.17)7Bnr translocation. The unexpected restoration of male fertility was observed in T43H/Rb7Bnr hybrids (T43H/+ males being completely sterile) which made it possible to prepare the first homozygotes for T43H male–sterile translocation. Direct estimation of chiasma frequencies in centromere 17−T43H region indicated an 11 cM distance between the centromere 17 and the proximal end of t12 haplotype. The significance of centromere −t (or H-2) distance on the predictable restrictions of the possible haploid manifestation of T-t or H-2 gene products on sperm membrane is discussed.
Article
The t haplotypes of mouse chromosome 17 are natural polymorphisms in wild populations that contain mutations that affect or control such diverse functions as tail length, embryonic lethality and maturation and function of male germ cells. The major impediment to dissecting the genetics of this complex region has been its unusual property of recombination suppression in heterozygotes with wild-type chromosomes. Recently it was shown that recombination suppression does not occur in heterozygotes containing two different t haplotypes, which suggested that t chromosomes may be mismatched with respect to wild-type but share sequences that permit crossing-over between them. Thus for the first time questions of allelism and map positions of the t-lethal mutations can be addressed. We report here the results of three experiments that analyzed the tw12 haplotype trans to either tw5, tw32 or tw18. In all cases these lethal mutations were nonallelic to tw12. These results, together with evidence for functional relatedness, suggest the t-lethals may be a gene family spread out over more than 15 centiMorgans of chromosome 17.
Article
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Article
In this second part of the Second Listing, we describe genes that constitute the H-2 complex proper. Here, we define the complex functionally as consisting of class I and class II loci (see Klein et al. 1983a). The H-2-associated complement loci and the Neu-1 locus have been described in the first part of the Second Listing (Klein et al. 1982), but for completeness we list them here again in some of the tables. We include into the H-2 complex the cluster of Qa and Tla loci, which we consider as class I loci (Klein et al. 1983). The genetic map of the definitely established loci appears in Figure 1 and is based on the recent results of molecular genetics studies (Steinmetz et al. 1982 a, b). For historical reasons we also describe loci (regions, subregions) that were once thought to be part of the H-2 complex but either they have since been withdrawn, or their actual existence is at present uncertain. We first list loci (regions, subregions) that have been designated by capital letters (we call it Madman's Alphabet because of the frivolity with which symbols have been introduced and then withdrawn again), and then other loci believed to be associated with the H-2 complex. As in the First Listing (Klein et al. 1978), the core of the review in the Second Listing constitutes the tables of H-2 haplotypes, antigens, and determinants.
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Article
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Article
The translocation break T(2;9)138Ca is located about three map units from the H-2 region on the non-centromeric side of the IXth linkage group. The recombination frequency in the T-H-2 interval is increased in the presence of the T138 translocation to about twice its value in the absence of the translocation.
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IT is still uncertain whether there is any gene activity in the haploid phase of mammalian sperm1, after meiosis in the maturing spermatids and spermatozoa. Two loci at which haploid activity possibly occurs in the mouse are the H-2 antigen locus and the T or brachyury locus, both situated near the centromeric end of chromosome 17 (linkage group IX)2. Evidence that the T-locus may act in the haploid phase comes from the effect of some alleles in distorting segregation ratios in the male3,4. Males heterozygous for certain recessive alleles give a very high proportion (up to 99%) of t-carrying young. Other alleles give an abnormally low proportion of young with the t-allele (10-20%) and yet others give a normal 1 : 1 ratio of + : t-carrying offspring. Although the mechanism of this effect is unknown it may well involve some action of the t-alleles concerned at the haploid stage. Antigens of the H-2 locus are expressed on mouse spermatozoa5. It has been claimed that both the human HL-A antigens and the mouse H-2 antigens on spermatozoa are produced by gene action at the haploid stage6, but for H-2 other authors have expressed doubt7.
Article
A cell-surface component specified by a mutant gene at the T-locus in the mouse has been detected on sperm by serological methods. The gene product thus recognized is not present on other adult cells.
Article
H-2 crossovers and their parental strains were arranged into 35 combinations in which the adult donor of spleen cells differed from the newborn recipient in the whole H-2 complex, or in three, two, or one region of the complex. A Simonsen splenomegaly assay was then used to test the contribution of the individual H-2 regions to the graft-versus-host reaction (GVHR). It was shown that the strongest GVHR was associated with the Ir region. Differences in the Ir region caused significant splenomegaly in spite of the fact that no antigens detectable by conventional serological methods have thus far been associated with this region. Differences in the K and D regions showed only a borderline effect on GVHR in spite of the fact that these regions code for most, if not all, of the antigens detectable by conventional serological and transplantation methods. The K region alone caused no stronger GVHR than the D legion alone; however, K + Ir region differences led to much stronger GVHR than D region differences. The Ss-Slp region also showed only a borderline effect on GVHR. Differences in two or more H-2 regions usually caused greater splenomegaly than differences in each of the regions separately. On the basis of these findings it is concluded that the strongest GVHR is caused by genes distinct from the known histocompatibility genes of the H-2 complex. It is speculated that the GVHR genes are identical with the mixed lymphocyte reaction (MLR) and Ir genes and that the product of these genes are receptors on the surface of the thymus-derived lymphocytes (T cells).
Chapter
The mapping of mouse mutations was a major project for the first half of the 20th Century. The early literature on the subject used confusing terms but Darbishire’s 1904 work was credited with showing the linkage of two color genes by the great geneticist, J.B. S. Haldane, his sister Naomi, and the deceased A.D. Sprunt in their 1915 paper. The American, Dunn credited Castle and Wright for the discovery for their 1915 paper. Linkages were rapidly found for a number of visible mutations and mapping increased at a logarithmic rate to mid-Century. Initially, the linkages were only “linkage groups’ but, as cytogenetics advanced and many chromosomal translocations were found, assignments to numbered chromosomes were made. As a number of biochemical and immunological markers were found and in vitro methods used, the number of assignments were so great that a committee of the scientists involved with each chromosome was needed to sort out the masses of data. Soon however, as the mouse genome was sequenced, placements became absolute by nucleotide number rather than just relative by crossover distances (centiMorgans) at the end of the Century.
Chapter
The t complex was originally discovered with the help of a mutation that appeared spontaneously in laboratory mice more than 60 years ago.(1) This brachyury (T) mutation caused shortening of the tail and was lethal in a homozygous state: the T/T embryos died at 10.5 days of gestation because of irregularities in the formation of the neural tube and notochord.(2) These irregularities are first noticeable morphologically at 8.5 days of gestation as blebs, vesicles, and deviations of the neural tube. At the time of death the notochord is either completely missing or is greatly reduced in size. By all accounts, the T is a point mutation in a locus that maps approximately 3 cM from the centromere on chromosome 17.(3)
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Chromosome 17 of the laboratory variant of the house mouse (Mus musculus L.), MMU17, has been studied extensively, largely because of its involvement in the control of immune response and embryonic as well as male germ cell differentiation. A detailed linkage map of this chromosome is therefore a highly desired goal. As the first step toward achieving this goal, we have isolated, using a LINE 1 repetitive sequence as a probe, 52 anonymous DNA clones from MMU17. Twenty-seven repetitive sequence-free probes isolated from these clones displayed restriction fragment length variation among common inbred strains and could be mapped with the help of recombinant inbred strains, congenic strains, F2 segregants, or intra-t recombinants. Together with markers identified previously, the new markers can be used to construct a map of MMU17 that contains 125 DNA loci. The markers are distributed over a length of approximately 71 cM, which probably represents the entire length of MMU17. Most of the markers reside in the proximal portion of the chromosome, which contains the t and H-2 complexes; this chromosomal region is now fairly well mapped. The distal region of MMU17, on the other hand, is populated by only a few, rather imprecisely mapped markers. Molecular maps are available for most of the H-2 complex and for parts of the t complex.
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Article
Apl, a gene involved in the processing of lysosomal acid phosphatase in mouse liver, has been mapped on Chromosome 17. The gene order and map distances in per cent recombination of the loci studied are T (20.6 +/- 3.4) Pgk-2 (7.4 +/- 2.2) Apl. Thus, Apl is at least 7 cM distal to H-2 on this chromosome. In addition, strain-specific allelic variants for Apl have been demonstrated on cellulose acetate gels, a quick and inexpensive method of electrophoresis.
Article
Full-text available
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Article
The downpour of information about the H-2 complex has hit immunology with the force of a tropical rainstorm. It is flooding whole fields, uprooting carefully cultivated orchards, displacing cottages, houses, and palaces, threatening to drown their inhabitants. This and the following article (Klein et al. 1982) are meant to serve as kinds of life-savers for those who have not learned how to swim in the rapid and murky waters. The First Listing, published four years ago (Klein et al. 1978), consisted only of tables; to this Second Listing we have added a brief description of all the loci residing, or thought to be residing, on the mouse chromosome 17, the chromosome carrying the H-2 complex. This arrangement necessitated the division of the Second Listing into two parts, the first part concerned with loci on chromosome 17 outside of the H-2 complex and the second part dealing with the complex itself. The discussion of the individual loci is prefaced by a description of the chromosome.
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Article
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Article
Full-text available
Somatic cell hybrids between an AKR mouse thymic lymphoma cell line and normal F344 rat spleen cells were isolated in order to assign the rat major histocompatibility complex (MHC) (RTl) to a specific chromosome. Six primary hybrid clones and 3 of their derivatives were examined for expression of the RTl antigens on the cell surface by the complement-dependent cytotoxicity test and simultaneously for their karyotypes by the Hoechst 33258/quinacrine mustard double staining method. All of these hybrid clones consisted of 2 sets of mouse and 1 set of rat parental cells, with a preferential loss of rat chromosomes. A high degree of concordance was shown between the expression of the RTl antigen and the presence or absence of rat chromosome 14 in the original 6 hybrid clones. This was confirmed in 1 spontaneous and 2 immunoselected RTl-negative segregants from RTl-posi-tive clones. These results led us to propose that the rat MHC is located on chromosome 14.
Article
Recent advances in genetic analysis of the major histocompatibility systems of various species and the first successful attempts at molecular dissection of their products contrast with the limited knowledge concerning the biological function of this particular part of the eukaryotic genome. The major histocompatibility system of the mouse, the H-2 system, adjoins closely the T/t genetic complex in chromosome 17. The T/t complex occupies a region of the chromosome 20 times longer than that pertaining to the H-2 system, and controls a variety of vital functions necessary for the development of the organism and survival of the species.
Article
Robertsonian chromosomes are metacentric chromosomes formed by the joining of two telocentric chromosomes at their centromere ends. Many Robertsonian chromosomes of the mouse suppress genetic recombination near the centromere when heterozygous. We have analyzed genetic recombination and meiotic pairing in mice heterozygous for Robertsonian chromosomes and genetic markers to determine (1) the reason for this recombination suppression and (2) whether there are any consistent rules to predict which Robertsonian chromosomes will suppress recombination. Meiotic pairing was analyzed using synaptonemal complex preparations. Our data provide evidence that the underlying mechanism of recombination suppression is mechanical interference in meiotic pairing between Robertsonian chromosomes and their telocentric partners. The fact that recombination suppression is specific to individual Robertsonian chromosomes suggests that the pairing delay is caused by minor structural differences between the Robertsonian chromosomes and their telocentric homologs and that these differences arise during Robertsonian formation. Further understanding of this pairing delay is important for mouse mapping studies. In 10 mouse chromosomes (3, 4, 5, 6, 8, 9, 10, 11, 15 and 19) the distances from the centromeres to first markers may still be underestimated because they have been determined using only Robertsonian chromosomes. Our control linkage studies using C-band (heterochromatin) markers for the centromeric region provide improved estimates for the centromere-to-first-locus distance in mouse chromosomes 1, 2 and 16.
Article
H-2 alleles of translocation stocks T138 and T190 were analyzed in the direct hemagglutination test and by in vivo absorption with oligospecific antisera. The alleles of both stocks were found to be indistinguishable from the H-2q allele of strain DBA/1. This conclusion was confirmed by an F1 test with skin grafts. The possible origin of the H-2q allele of the translocation stocks and its possible relationship to H-2q alleles of other strains are discussed. An H-2 recombinant which arose by crossing over between H-2a of BIO.A and H-1q of T138 was also analyzed. The recombinant has a new combination of H-2v antigens which we propose to call H-2v. The H-2y allele has its D end derived from H-T and its K end derived from H-21. Factors controlling antigens H-2.17 and H-2.30 are placed by this recombinant in the opposite sides from Sip in the H-2 map. On the basis of these and other data, it is hypothesized that H-2m allele of strain AKR.M might have also arisen by crossing over between alleles H-2K of strain AKR and H-2q of noninbred strain M.
Article
Single strands of mouse satellite DNA were annealed to nuclei and chromosomes in mouse cells. From the location of autoradiographic grains, it is suggested that there is a concentration of satellite DNA sequences close to the centromeres of the chromosomes.
Article
In mice heterozygous for translocation T(2;?)163H, and also for linkage group II markers, the cw locus shows close linkage with the point of rearrangement (about 1−2% recombination). Since T 163 was apparently formed by fusion of two chromosomes near their centromeres, this means that the centromere must lie at the cw end of linkage group II. In homozygotes for T(2; 9)138Ca the genes T and d show significant linkage, indicating that their loci are on opposite sides of the trans-location break. Since, from previous data, the break is known to be proximal to d , it must then be distal to T and, again from previous data, the order of loci hi linkage group IX must be centromere- T - tf -T 138 break.
Article
The method was developed for bone marrow of mice but is applicable to other tissues and other species of small mammals. Mice are injected intraperitoneally with 0.5 ml of 0.025% colchicine solution and killed 1 hr afterwards. The femurs are dissected out rapidly, the epiphyses are removed, and the marrow is washed out of the shafts by warm hypotonic sodium citrate solution from a hypodermic syringe. Gentle aspiration of the marrow into and out of the syringe converts it into a fine suspension. The suspension is kept in the citrate solution at 37°C for 10 min. Connective tissue and bony spicules are removed by centrifuging through Nylon bolting cloth in a bacterial filtration tube, before fixing in acetic-alcohol (1:3) and staining by the standard Feulgen procedure. The cells are concentrated for each change of reagent by centrifuging slowly. The advantages of colchicine pretreatment and of working with cell suspensions are emphasized.
Article
Previous studies on isoantigenic variation in heterozygous mouse tumors have shown that cells with genetic information controlling H-2 antigens D and K in the cis position, i.e., on the same chromosome, did not give rise to D−K+ variants, while D−K− and D+K− variants were readily obtained. This was tentatively attributed to a chromosomal mechanism involving either deletion or, more probably, somatic crossing over. Another explanation that could not be excluded, however, was that D is a precursor of K. In the present work, neoplasms were studied that contained the genetic determinants for the same two antigens on two different homologous chromosomes, i.e., in the trans position. In this situation, the previously missing D−K+ variants were readily obtained. This makes the precursor hypothesis less probable and strengthens the postulate that the formation of isoantigenic variants has a chromosomal mechanism.
Article
A suspension is made in isotonic (2.2%) sodium citrate solution from the contents of the tubules from a whole testis or a testicular biopsy specimen. The germinal cells are sedimented by centrifuging, leaving most of the sperm in the supernatant fluid, which is discarded. The cells are resuspended in hypo-tonic (1%) sodium citrate solution and left to stand at room temperature for 12 minutes, after which they are sedimented again and fixed as a concentrated suspension in a mixture of 3 parts absolute ethyl alcohol to 1 part glacial acetic acid plus a trace of chloroform. Two quick changes into fresh fixative follow. Air-dried preparations are made from the final fixed suspension and stained in lactic-acetic-orcein. The method is suitable for stages of male meiosis in which the chromosomes are condensed. Its principle advantage is the separation of the clumps of spermatogonia and spermatocytes into individual cells which are randomly dispersed over the preparations. Compared with squash techniques, the air-drying method gives improved spreading of the chromosomes and less cell breakage.Copyright © 1964 S. Karger AG, Basel
  • S L Allen
Allen, S. L., Genetics, 40, 1627 (1955).
  • J Klein
  • D Klein
  • D C Shreffler
Klein, J., D. Klein, and D. C. Shreffler, Transplantation, 10, 309 (1970).
  • E Klein
  • G Klein
  • J Nat
Klein, E., and G. Klein, J. Nat. Cancer Inst., 32, 569 (1964).
  • J Klein
Klein, J., Genetics, 64, s35 (1970).
  • J H Stimpfling
Stimpfling, J. H., Transplant. Bull., 27, 109 (1969).
  • T C Carter
  • M F Lyon
  • R J S Phillips
Carter, T. C., M. F. Lyon, and R. J. S. Phillips, J. Genet., 53, 154 (1955).
  • A Ldonard
  • G H Deknudt
Ldonard, A., and G. H. Deknudt, Experientia, 22, 715 (1966).