Rearrangement of VHa1-encoding Ig gene segment to the a2 chromosome in an a1/a2 heterozygous rabbit. Evidence for trans recombination

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.     

斯卑尔脱小麦1B染色体的显微分离及其DNA的PCR扩增

以斯卑尔脱小麦的一个变种及其近等基因系为材料,玻璃针法进行显微操作在减数分裂中期I分裂相中获得G型细胞质雄性不育的育性恢复基因Rf₃所在的1B染色体DNA。LA-PCR方法扩增DNA,斑点杂交的方法检测证明扩增产物来源于斯卑尔脱小麦基因组的1B染色体DNA。     

The gene that encodes the human CD20 (B1) differentiation antigen is located on chromosome 11 near the t(11;14)(q13;q32) translocation site

The human CD20 gene (B1) encodes a B lymphocyte-specific, cell-surface molecule that is involved in B cell activation and differentiation. We report that the CD20 gene is located on human chromosome 11 at position q12-q13. The location of CD20 was determined by in situ hybridization and was further confirmed by Southern blot analysis of DNA from rodent/human hybrids that contained only portions of human chromosome 11. This localization places the CD20 gene near the site of the t(11;14)(q13;q32) translocation that is found in a subgroup of B cell-lineage malignancies. The site of this translocation has been previously identified by DNA cloning and termed bcl-1. The CD20 gene was found to lie on the centromeric side of bcl-1 on chromosome 11 and to be separated from bcl-1 by at least 50 kb of DNA. These results raise the possibility that alterations in the expression of the CD20 gene may result after the t(11;14) chromosomal alteration.     

Genetic analysis of anther culture response in wheat using aneuploid,chromosome substitution and translocation lines

Summary Marked effects of genotype on wheat anther culture response have been observed. Genetic factors have been recognised to be one of the major contributors to in vitro responses of cultured wheat tissues. In wheat anther culture, embryo induction, plant regeneration and albina/green ratio have been determined to be heritable traits. Using Chinese Spring (CS) monosomic 1D, single chromosome substitution lines of chromosome 5B or chromosome arm 5BL from Chinese Spring into six varieties, and F₁ hybrids heterozygous for the 1B chromosome structure (1BL-1BS/1BL-1RS), the anther culture response was studied: genes on CS1D chromosome and 5BL chromosome arm increases the embryo frequency; gene(s) involved in regeneration ability are located on the 1RS chromosome arm; a gene increasing albina frequency is located on Chinese Spring 5B chromosome. Our results support the fact that without gametic selection, a differential development occurred from the particular classes of microspores carrying genes for higher regeneration ability. Moreover, in some crosses, a few genes with major effects were involved in determination of anther culture response.     

Analysis of inheritance of morphological and biochemical characters introgressed into common wheat from Aegilops speltoides Tausch

Genetic control of some morphological traits and the gliadin composition were examined in plants of two lines of common wheat carrying genes introgressed from the wild diploid cereal Aegilops speltoides. Leaf hairiness was shown to be controlled by a single introgressed dominant gene that was not allelic to the known common wheat gene Hl1. Waxlessness of the whole plant is controlled by the introgressed from Ae. speltoides inhibitor gene allelic to gene W1 located on chromosome 2B. This gene was epistatic to the introgressed gene controlling spike waxlessness. The introgressed gene of spike color was shown to be allelic to Rg1 located on chromosome 1B of common wheat. However, the former gene proved to be linked to an allele of the Gli-B1 locus other than in wheat.     

Chromosomal localization of a gamete-killing gene in a wheat line

Monosomic analysis revealed that a gametocidal gene in a common wheat line derivative from Aegilops speltoides is located on chromosome 2B. This gene induces semisterility, low level of chromosome breaks, shriveled seeds, and endosperm degeneration. The obtained data indicate that the localized gene is allelic to well known gametocidal genes Gc1a and Gc1b.     

Geographic variability in expression of the sex-linked AAT-1 gene of the bell-ring frog, Buergeria buergeri

Cytological observation and artificial crossing experiments were used to examine the geographic differences in the sex-determining mechanism and mode of inheritance of the sex-linked AAT-1 gene in the bell-ring frog, Buergeria buergeri. The AAT-1 phenotypes were also examined by allozyme analysis using field-caught females and males collected from 19 populations from the Honshu, Shikoku, and Kyushu islands of Japan, in order to comprehensively elucidate the geographic variability in the expression of the sex-linked AAT-1 gene of B. buergeri. The results showed that the Aomori population of B. buergeri from the northern end of Honshu was female heterogametic in sex determination, that chromosome No. VII was a sex chromosome of the ZZ/ZW type, and that the sex-linked AAT-1 gene was expressed on both the Z and W chromosomes. This mode of AAT-1 expression in the Aomori population was different from that in the Hiroshima population from western Honshu, in which the AAT-1 gene was expressed on the Z chromosome but not on the W chromosome. The results also showed that there was no differentiation among populations in the expression of the AAT-1 genes on the Z chromosome, whereas two populations, the Hiroshima and Aomori frogs, exhibited distinct modes of expression of the AAT-1 gene on the W chromosome. These two modes of expression may be widely distributed in western and eastern Japan, and coexist in the central part of Honshu.     

Natural or induced nucleocytoplasmic heterogeneity in Triticum longissimum.

Alien cytoplasms produce a variety of phenotypes in durum wheat (Triticum turgidum) and common wheat (Triticum aestivum) cultivars, which indicate the prevalence of cytoplasmic variability in the subtribe Triticinae. Intraspecific cytoplasmic differences have been demonstrated between the subspecies of Triticum speltoides, Triticum dichasians, and Triticum comosum. In this study, durum wheat lines with cytoplasm from two accessions, B and C, of Triticum longissimum were compared, and meiotic chromosome pairing between the group 4 homoeologues from the same two accessions was examined in common wheat. First, monosomic addition or monosomic substitution lines of common wheat with cytoplasm and one chromosome (designated B) from accession B were crossed with those having cytoplasm and a chromosome designated C-1 or C-2 from accession C. In each substitution line, an alien chromosome substituted for a group 4 homoeologue. Each alien chromosome had a "selfish" (Sf) gene, which remained fixed in the wheat nucleus. The F1s had greatly reduced meiotic pairing between chromosomes B and C-1 and B and C-2, which indicated greatly reduced homology between the group 4 homoeologues from the two accessions. Second, by using Triticum timopheevii as a bridging species, chromosome B in a common wheat line was eliminated and an euploid durum line with cytoplasm from accession B was obtained. This line was fertile. In contrast, a similarly produced durum line with cytoplasm from accession C was male sterile and retained a species cytoplasm specific (scs) nuclear gene from T. timopheevii. In conclusion, nuclear and cytoplasmic heterogeneity pre-existed between accessions B and C and they represent varieties or incipient subspecies in T. longissimum. Alternatively, the Sf genes produced chromosomal heterogeneity and mutated cytoplasmic genes from one or both accessions. Key words : meiotic drive, selfish gene (Sf), gametocidal gene (Gc), Triticum, Aegilops.     

Mapping genes affecting flowering time and frost resistance on chromosome 5B of wheat

Two populations of single chromosome recombinant lines were used to map genes controlling flowering time on chromosome 5B of wheat, and one of the populations was also used to map a new frost resistance gene. Genetic maps were developed, mainly using microsatellite markers, and QTL analysis was applied to phenotypic data on the performance of each population collected from growth-room tests of flowering time and frost tolerance. Using a recombinant substitution-line mapping population derived from a cross between the substitution-line 'Chinese Spring' ('Cheyenne' 5B) and 'Chinese Spring' (CS), the gene Vrn-B1, affecting vernalization response, an earliness per se locus, Eps-5BL1, and a gene, Fr-B1, affecting frost resistance, were mapped. Using a 'Hobbit Sib' ('Chinese Spring' 5BL) x 'Hobbit Sib' recombinant substitution line mapping population, an earliness per se locus, Eps-5BL2 was mapped. The Vrn-B1 locus was mapped on the distal portion of the long arm of chromosome 5B, to a region syntenous with the segments of chromosomes 5A and 5D containing Vrn-A1 and Vrn-D1 loci, respectively. The two Eps-5BL loci were mapped close to the centromere with a 16-cM distance from each other, one in agreement with the position of a homoeologous locus previously mapped on chromosome 5H of barley, and suggested by the response of 'Chinese Spring' deletion lines. The Fr-B1 gene was mapped on the long arm of chromosome 5B, 40 cM from the centromeric marker. Previous comparative mapping data with rice chromosome 9 would suggest that this gene could be orthologous to the other Fr genes mapped previously by us on chromosomes 5A or 5D of wheat, although in a more proximal position. This study completes the mapping of these homoeoallelic series of vernalization requirement genes and frost resistance genes on the chromosomes of the homoeologous group 5 in wheat.     

Physical mapping of the HOXA1 gene and the hnRPA2B1 gene in a YAC contig from human chromosome 7p14-p15

A cluster of homeobox-containing genes (HOXA) and a heterogeneous nuclear ribonucleoprotein (hnRPA2B1) have both previously been assigned to chromosome 7p15 by in situ hybridization. In this report, we constructed a YAC contig from chromosome 7p14-p15, between markers D7S2496 and D7S1838, and determined the position of the HOXA1 gene and the hnRPA2B1 gene in this YAC contig. Received: 19 November 1996 / Revised: 2 January 1997     

Genetic control of mutability in laboratory mice. I. Genetic analysis of the sensitivity of mice of strains 101/H and C57BL/6 to the mutagenic effect of thio-TEPA]

The distribution of male mice of the BC1 generation was analysed with respect to the frequency of chromosome aberrations in bone marrow cells induced by thio-TEPA. The BC1 descendants were derived from the F1 of the cross (C3H X 101) X 101 and the F1 of the cross (CBA X B6) X B6. With respect to mutability the BC1 descendants of both types could be divided into two classes. The average frequencies of the cells with chromosome aberrations in the BC1 descendants of the 101 line were in the two classes 33.4 and 64.2 percent respectively. The corresponding values for the two classes of the BC1 descendants of the B6 line were 24 percent and 33.2 percent respectively. These data suggest that each of the lines studied has one recessive mutator gene. Preliminary symbols are proposed: mut-1 for the gene of the line 101/H and mut-2 for the gene of the line B6. The gene mut-2 is linked with the gene a (nonagouti) (Vth linkage group, chromosome 2).     

Comparative study on effect of different promoters on expression of cry1Ac in Bacillus thuringiensis chromosome

AIMS: The aim of this work was to investigate the effect of cry3A promoter on the expression of cry1Ac in Bacillus thuringiensis chromosome and stably enhance the production of different cry genes under the control of cry3A promoter. METHODS AND RESULTS: The cry1Ac gene, which is specific to Lepidopteran larvae, was integrated into the chromosome of a B. thuringiensis plasmid-free and acrystalliferous strain BMB171, under the control of cry3A promoter and cry1Ac promoter, respectively. The expression of cry1Ac genes in the chromosome of host strain was investigated. The results from sodium dodecyl sulfate-polyacrymide gel electrophoresis, crystal observation and bioassay showed that either integrated with cry3A promoter (cry3Apro-cry1Ac) or with its native promoter (cry1Acpro-cry1Ac), cry1Ac gene could efficiently and stably express in the chromosome. The production of cry3Apro-cry1Ac gene was higher than that of cry1Acpro-cry1Ac gene. CONCLUSIONS: The cry3A promoter enhanced the expression of cry1Ac gene efficiently either on the chromosome or on the plasmid in B. thuringiensis strain. SIGNIFICANCE AND IMPACT OF THE STUDY: So far, the comparative studies on cry3A promoter and other cry promoters were carried on B. thuringiensis plasmids. This system offers an additional method for potentially improving the efficacy of B. thuringiensis insecticidal proteins efficiently, stably and safely.     

The transfer of genes for Brown Rust resistance from Aegilops umbellulata Eig. to wheat (Triticum aestivum L.) genome

The potential of a genome-substituted form Avrolata (AABBUU) as a genetic system in genomic and chromosome manipulations for gene transfer from the wild species Aegilops umbellulata Eig. (UU) to cultivated wheat was studied. It was shown that plants combining resistance to leaf brown rust with high productivity may be produced from this form by classical hybridization procedures. The resistance gene introduced to line R-12 is dominant and probably identical to the Lr9 gene. By N-banding, chromosome staining technique and gliadin electrophoresis, the structural changes in chromosomes 1A, 2A, 4B, 6B, 7B, 1D, and 2D of the resistant line R-12 were revealed.     

Gene Dosage and the Expression of Electrophoretic Patterns in Heteroploid Mouse Cell Lines

Spontaneously transformed mouse cell lines heterozygous for electrophoretic markers have been studied to determine the relationship between gene dosage and phenotype. It is shown that a clone with an electrophoretic pattern for glucosephosphate isomerase of three bands in a ratio of 4A:4AB:1B contains three copies of chromosome 7, which carries the gene for this enzyme. A clone from a different line with a pattern of three bands in a ratio of 1A:6AB:9B for NADP-isocitrate dehydrogenase has four copies of the chromosome carrying this gene or three copies plus a rearrangement which apparently involves this chromosome. These results show that all of the alleles for each enzyme are expressed to an equal extent in these cells.     

Transfer of chromosomal genes and plasmids in Bacillus thuringiensis.

A low frequency of chromosomal gene transfer from Bacillus thuringiensis to Bacillus cereus was detected by cell mating, with a tryptophan marker being the most frequently transferred gene among four that were tested. The process was resistant to DNase and was not mediated by cell filtrates. Among several B. thuringiensis subspecies tested, transfer was best with a derivative of B. thuringiensis subsp. kurstaki HD1, which lost several plasmids. All of the B. cereus recombinants contained at least one plasmid from the donor B. thuringiensis; frequently, it was a plasmid that encoded a protoxin gene. In matings with B. thuringiensis subsp. kurstaki HD1, a 29-megadalton plasmid that contained a ca. 2.5-kilobase region of homology with the chromosome was always transferred. No detectable transfer of chromosomal genes was found in B. thuringiensis subsp. kurstaki HD1 strains lacking this plasmid, suggesting that there may be chromosome mobilization.     

Transfer of chromosomal genes and plasmids in Bacillus thuringiensis

A low frequency of chromosomal gene transfer from Bacillus thuringiensis to Bacillus cereus was detected by cell mating, with a tryptophan marker being the most frequently transferred gene among four that were tested. The process was resistant to DNase and was not mediated by cell filtrates. Among several B. thuringiensis subspecies tested, transfer was best with a derivative of B. thuringiensis subsp. kurstaki HD1, which lost several plasmids. All of the B. cereus recombinants contained at least one plasmid from the donor B. thuringiensis; frequently, it was a plasmid that encoded a protoxin gene. In matings with B. thuringiensis subsp. kurstaki HD1, a 29-megadalton plasmid that contained a ca. 2.5-kilobase region of homology with the chromosome was always transferred. No detectable transfer of chromosomal genes was found in B. thuringiensis subsp. kurstaki HD1 strains lacking this plasmid, suggesting that there may be chromosome mobilization.     

Cloning and characterization of maize B chromosome sequences derived from microdissection

Isolation of sequences from the maize B chromosome is always hampered by its high homology with the normal complements. In this study, this handicap was overcome by cloning the sequences from the pachytene B chromosomes dissected out of a slide by a micromanipulator followed by degenerate oligonucleotide-primed PCR. The isolated sequences were found to hybridize with genomic DNA in a B-dosage-dependent manner and with the pachytene B chromosome by fluorescence in situ hybridization (FISH), corroborating their B origin. A total of 19 B sequences were isolated, all of which are repetitive and, with one exception, are homologous to the A chromosome(s). Three sequences have strong homology to maize sequences that include two knob repeats and one zein gene (noncoding region), and 10 others are homologous to the noncoding region of Adh1, Bz1, Gag, Zein, and B centromere to a lesser degree. Six sequences have no homology to any gene. In addition to FISH, the B-specific sequence and a partially B-specific one were also mapped, by seven newly characterized TB-10L translocations, to a similar location on the central portion of the distal heterochromatic region, spreading over a region of about one-third of the B chromosome.     

Chromosomal location of genes for resistance to powdery mildew in Chinese wheat lines Jieyan 94-1-1 and Siyan 94-1-2

Two Chinese wheat lines Jieyan 94-1-1 and Siyan 94-1-2 are resistant to all 120 isolates of Blumeria graminis f. sp. tritici maintained in Weihenstephan, Germany. Monosomic analyses employing the susceptible set of 21 Chinese Spring monosomic lines revealed that the line Jieyan 94-1-1 carries one dominant gene on translocated wheat/rye chromosome 1B/1R and one recessive gene on chromosome 7B, whereas line Siyan 94-1-2 possesses one recessive gene on chromosome 7B and one dominant gene on chromosome 5D. Allelism tests in combination with the use of specific isolates comfirmed that the dominant genes in Jieyan 94-1-1 and Siyan 94-1-2 are Pm8 and Pm2, respectively. The recessive genes present in each of the two lines are shown to be new alleles located on chromosome 7B at the pm 5 locus. The two genes are tentatively designated mljy in Jieyan 94-1-1 and mlsy in Siyan 94-1-2, respectively.