甘蓝型油菜pol CMS育性恢复基因对orf224/atp6的转录调控

用 10个线粒体基因探针对波里马细胞质雄性不育 (polimaCMS)三系 1141A(pol) ,1141B(nap)和 1141R(pol)的花蕾线粒体RNA进行了Northern检测。结果表明 ,只有 3个探针atp6、orf2 2 4和orf2 2 2检测到转录本的差异。atp6在可育的 1141B中只转录产生一个丰度很高的 1 1kb转录本 ,在雄性不育的 1141A和pol胞质恢复系 1141R中 ,这个转录本的丰度明显减少并出现了分子量较大的 2个转录本 2 2kb、1 9kb转录本。与 1141A相比 ,恢复系1141R的 2 2kb和 1 9kb转录本丰度明显减少 ,并伴随着两个新的转录本 1 4kb和 1 3kb。表明orf2 2 4 atp6的表达与polCMS有关 ,并且其转录受到恢复基因Rfp的调控。同时通过对杂种F1 ( 1141A× 1141R)与另一个恢复系RS35 (pol)的比较证实 ,Rfp对orf2 2 4 atp6的调控与Rfp纯合与否无关。orf2 2 4 atp6在 1141A的苗期叶片中还转录产生育性恢复特异的 1 4kb转录本 ,这可能与细胞核基因型和相对低温条件有关。     

Genetic regulation of CFA expression in interspecific avian hybrids and somatic cell hybrids

Chicken fetal-leukemic antigen (CFA) is an oncodevelopmental antigen present on embryonic and neonatal chicken peripheral red blood cells (RBCs) but is not restricted to fetal stages of development in other avian species. Crosses between white Leghorn chickens and Japanese quail resulted in adult hybrids whose peripheral RBCs were positive for CFA. Of the four CFA determinants normally found in adult quail RBCs, only two were present on quail-chicken hybrid RBCs. Adult quail--chicken hybrid RBCs also possessed on CFA determinant associated with early development in both quail and chicken and one chicken-specific CFA determinant. Evidence is presented for the possible association of CFA-positive adult peripheral RBCs and the level of circulating reticulocytes. Crosses between pheasant and turkey (both with CFA-positive adult RBCs) resulted in hybrid adult RBCs expressing only a portion of the parental CFA determinants. Through the formation of somatic cell hybrids between adult chicken and embryonic Japanese quail RBCs, it was possible to induce the appearance of CFA determinants normally restricted to embryonic chicken RBCs. Approximately 50% of the hybrid cells showed reexpression of CFA, and this induction was both time and temperature dependent. Hybridization between RBCs of adult chicken and those of either adult Japanese quail or adult turkey failed to elicit the reexpression of chicken-specific CFA.     

Production of fertile intergeneric somatic hybrids between Brassica napus and Sinapis arvensis for the enrichment of the rapeseed gene pool

Somatic hybrids between Brassica napus (oilseed rape) and its wild relative Sinapis arvensis (Xinjiang wild mustard) from northwestern China were produced by fusing mesophyll protoplasts. Fifty-four plants were identified as symmetric hybrids and four as asymmetric hybrids by random amplified polymorphic DNA analysis and nuclear DNA content. The morphology of investigated 58 hybrid plants resembled characters from both parental species. Highly fertile hybrids were recovered where the fertility was associated with the choice of B. napus genotype. Enhanced disease resistance to Leptosphaeria maculans was found in S. arvensis and in the hybrid offspring. This plant material has great potentials not only for use as a bridge for the introduction of a number of valuable traits from the wild species to Brassica crops but also for breeding new varieties with improved blackleg resistance.     

Destabilization of the adenosine deaminase gene sequences in rat-rat somatic cell hybrids

Rat hepatoma cells amplified for adenosine deaminase (ADA) gene sequences show the amplified DNA on large, homogeneously staining regions (HSRs). The amplified cells are stable in the absence of selection for 12 mo without loss of ADA activity or gene sequences. However, in hybrids formed between an amplified cell line with a prominent HSR and a nonamplified cell line, rapid loss of ADA activity, as well as gene sequences, occurs. Karyotype analyses of the hybrids indicate that the HSR structures are no longer visible in a large percentage of the hybrid metaphase spreads and appear to have been replaced by DNA structures that resemble double minutes. Our data provide evidence that the extent of the breakdown of the HSR in the hybrids may be affected by the presence of an active adenosine kinase or the level of ATP in the cells and additional unidentified factors are present in the hybrids that affect the integrity of the HSR structure. There is no evidence for a specific trans-acting factor in nonamplified cells that regulates gene amplification.     

Synthesis of high erucic acid rapeseed (Brassica napus L.) somatic hybrids with improved agronomic characters

Novel Brassica napus somatic hybrids have been created through protoplast fusion of B. oleracea var. botrytis and B. rapa var. oleifera genotypes selected for high erucic acid (22:1) content in the seed oil. Fifty amphidiploids (aacc) and one putative hexaploid (aacccc) hybrid were recovered in one fusion experiment. Conversely, only one amphidiploid and numerous regenerates with higher DNA contents were produced in a similar fusion using a different B. rapa partner. Hybridity was confirmed by morphology, isozyme expression, flow cytometry, and DNA hybridization. Analysis of organellar DNA revealed a distinct bias toward the inheritance of chloroplasts from the B. rapa (aa) genome. All amphidiploids set self-pollinated seed. A erucic acid content as high as 57.4% was found in the seed oil of one regenerated plant. Fatty acid composition was stable in the R₁ generation and was coupled with increased female fertility. Other novel agronomic characters in the hybrids recovered include large seed size, lodging resistance, and non-shattering seed pods.     

Possible assignment of the glyoxalase I (GLO) gene to chromosome 6 using man-mouse somatic cell hybrids

Summary A correlation between the expression or absence of human glyoxalase I and chromosome 6 (as well its markers ME₁, IPO-B, and PGM₃) was observed in man-mouse somatic cell hybrids. This segregation pattern indicates that the GLO gene is situated on chromosome 6.

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Zusammenfassung In Hybriden somatischer Zellen zwischen Maus und Mensch wurde eine Korrelation zwischen Vorhandensein bzw. Abwesenheit der menschlichen Glyoxalase I und von Chromosom 6 (sowie seinen Markern ME₁, IPO-B und PGM₃) ermittelt. Diese Korrelation spricht dafür, daß das GLO-Gen auf Chromosome 6 liegt.

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Supported by the Deutsche Forschungsgemeinschaft BE 352/8 and GR 373/6.     

Intertribal somatic hybrids between Brassica napus and Thlaspi perfoliatum with high content of the T. perfoliatum-specific nervonic acid

Protoplast fusions were performed between hypocotyl protoplasts of Brassica napus and mesophyll protoplasts of Thlaspi perfoliatum. The two species are members of the Lepidieae and Brassiceae tribes, respectively, in the family of Brassicaceae. Seeds of T. perfoliatum are rich in the fatty acid C₂₄₁ (nervonic acid), an oil valuable for technical purposes. In the search for renewable oils to replace the mineral oils, plant breeders have been trying to develop oil crops with a high content of long-chain fatty acids. After fusion of B. napus protoplasts with non-irradiated as well as irradiated protoplasts of T. perfoliatum selection was carried out by flow cytometry and cell sorting. Of the shoots regenerated from different calli 27 were verified as hybrids or partial hybrids using the isoenzyme phosphoglucose isomerase (PGI) as a marker. Another 6 plants were identified as partial hybrids using a T. perfoliatum-specific repetitive DNA sequence. Slot blot experiments were performed to estimate the copy number of the repetitive DNA sequence in the parental species and in the hybrids. In T. perfoliatum there were approximately 10⁵ copies per haploid genome, and the range in the hybrids was 1–37% of the value in T. perfoliatum. When the nuclear DNA content of the regenerated shoots was analysed we found partial as well as symmetric hybrids. Even though the rooting and establishment of hybrid shoots in the greenhouse were difficult, resulting in the death of many plants, 19 plants were cultured to full maturity. Seeds obtained from 15 plants were analysed to determine whether they contained nervonic acid, and 5 of the hybrids were found to contain significantly greater amounts of nervonic acid than B. napus.     

Assignment of the catechol-O-methyltransferase gene to human chromosome 22 in somatic cell hybrids

Summary Catechol-O-methyltransferase (COMT) plays an important role in the inactivation of catecholamines. It has been demonstrated that erythrocyte COMT activity is genetically determined and controlled by a major autosomal locus with two alleles. The recent development of a method which allows the detection of COMT isozymes directly in autoradiozymograms has provided the means to investigate the chromosome location of the gene by using somatic cell hybrids. We have found that a single form of the COMT enzyme is expressed in several mouse-human fibroblast cell lines. The data obtained from the segregation analysis of the COMT enzyme in these hybrids and their subclones have provided evidence for the location of a major gene for COMT activity on human chromosome 22.     

Creation and analysis of Brassica napus + Arabidopsis thaliana somatic hybrids possessing maize Spm/dSpm heterologous transposable system

Functionally asymmetric somatic hybrids possessing heterologous transposable element Spm/dSpm were obtained following intertribal somatic hybridization between Brassica napus and transgenic Arabidopsis thaliana. Mobile genetic elements actively transposed in the hybrid genomes. Complete elimination of A. thaliana genome was not observed.     

Genetic evidence for the hybrid nature of somatic hybrids from Datura innoxia Mill.

The hybrid nature of tetraploid somatic hybrids of two genetically different chlorophyll-deficient mutants from Datura innoxia Mill. was demonstrated with the aid of anther culture. Green and chlorophyll-deficient androgenetic lines could be regenerated from the pollen grains.     

Genetic complementation in somatic cell hybrids of four variants of infantile GM2 gangliosidosis

Summary Cell hybridizations between fibroblasts of four variants (B, O, AB, and B1) of infantile G_M2 gangliosidosis were performed. Cocultivated as well as hybrid cells were analyzed for their capability to degrade exogenously added [³H]-G_M2. Hybridization of variant AB fibroblasts with fibroblasts of variant O, variant B, or variant B1 resulted in an enhanced rate of G_M2 hydrolysis, showing intergenic complementation. Similar restoration of G_M2 catabolism was observed after hybridization of variant B1 cells with variant O, but not with variant B cells. These results indicate that B1 cells carry a mutation in the gene locus for the α-subunit of β-hexosaminidase. Studies of the processing of immature enzyme in variant B1 cells showed the presence of α-precursors and mature α-chains, but at a lower level as compared to normal cells.     

Selection of a universal hybridizer in Sinapis turgida Del. and regeneration of plantlets from somatic hybrids with Brassica species

A double-mutant cell line, which was unable to grow in a medium with NO ₃ ^- as the sole nitrogen source and was resistant to 5-methyl-tryptophan (5MT), was selected from cell suspensions of Sinapis turgida Del. (Brassicaceae) by culturing the cells in AA medium (Toriyama and Hinata, 1985, Plant Sci. 41, 179–183) supplemented with 50 mM chlorate and 229 M 5MT. Protoplasts of this cell line were fused with mesophyll protoplasts of Brassica oleracea L. with dextran, and six somatic hybrids were selected initially by culture in the NO ₃ ^- medium and then by transfer to the NO ₃ ^- medium supplemented with 229 M 5MT. The somatic hybrids produced embryoids, leaves and plantlets on a regeneration medium. The hybrid characters were confirmed by investigations of acid phosphatase (EC 3.1.3.2) and peroxidase (EC 1.11.1.7) isoenzymes, chromosome number, growth on NO ₃ ^- medium, 5MT resistance, and capacity to regenerate plants. Somatic hybrids between S. turgida Del. and B. nigra (L.) Koch were also obtained using this method. These results indicate that the double-mutant cell line established here will be able to serve as a universal hybridizer to select somatic hybrids after protoplast fusion with any other wild-type partner.Abbreviations B5 medium of Gamborg et al. (1968) - MS medium of Murashage and Skoog (1962) - 5MT 5-thethyltryptophan     

Genetic distance estimates among single cross hybrids and correlation with specific combining ability and yield in corn double cross hybrids

The objective of the present study was to correlate the genetic distances (GD) of single cross hybrids with yield, heterosis and specific combining ability (SCA) in the double cross hybrid synthesis. For this, 10 single cross commercial hybrids were used from different companies, and all the possible double hybrids were synthesized by a complete dialell. The hybrids were assessed in 15 locations in the 2005/2006 agricultural season, using the randomized complete block design with three repetitions. DNA was extracted from the single cross hybrids and 20 simple sequence repeat primers were used, nine of which were linked to the quantitative trait loci. It was ascertained that the single hybrids were superior in general to the double cross hybrids and that yield was highly correlated with heterosis and SCA (r = 0.75 and 0.82, respectively). There was no significant correlation between yield and GD (r = 0.25), but this index was at the limit of significance. There was a medium correlation between GD and heterosis (r = 0.40) and GD and SCA (r = 0.38). The intergroup hybrids placed by genetic grouping were generally more productive than intragroup hybrids, and the hybrids with GD greater than 0.84 had the maximum heterosis and SCA. It was concluded that the markers were efficient in placing hybrids in different heterosis groups and were also useful in eliminating the most negative heterosis and SCA.     

Regulation of glucose 6-phosphate dehydrogenase expression in CHO-human fibroblast somatic cell hybrids

Human--hamster somatic cell hybrids have been obtained by fusion of a CHO line (NA31) doubly deficient in hypoxanthine guanine phosphoribosyltransferase and glucose 6-phosphate dehydrogenase (G6PD) with normal G6PD(+) human fibroblasts. Analysis of NA31 extracts has revealed that, although G6PD activity is nearly absent, significant activity can be detected with 2-deoxyglucose 6-phosphate as substrate, so that the mutant and normal forms of the enzyme can both be easily detected. The cell hybrids obtained express human G6PD. The human G6PD subunits are distributed in homodimeric molecules as well as in human--hamster heterodimeric molecules. However, whereas the amount of hamster G6PD subunits present in the hybrid is similar to that in the hamster parental cells, the amount of human G6PD subunits is decreased by 3- to 10-fold when compared to the human parental cell. These results indicate that either the expression of the G6PD gene or the stability of the gene product is altered in the hybrid. By mutagenesis and selection in diamide (a substance that oxidizes intracellular glutathione), we have isolated a clone with a 3- to 5-fold increase in human G6PD activity. This derivative may have an increased rate of expression of the human G6PD structural gene.