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31.
The role of cell differentiation state and HMG-I/Y in the expression of transgenes flanked by matrix attachment regions 总被引:1,自引:0,他引:1
Ascenzi Robert Ingram Jennifer L. Massel Mara Thompson William F. Spiker Steven Weissinger Arthur K. 《Transgenic research》2001,10(5):465-470
The tobacco nuclear matrix attachment region (MAR), RB7, has been shown to have a much greater effect on transgene expression in cultured cells than in transgenic plants. This is comparable to work in mouse systems showing that MARs have a positive effect on transgene expression in embryonic tissues but not adult tissues. There are several possible explanations for these observations. One is that cell differentiation state and proliferation rate can affect MAR function. We tested this possibility by initiating suspension cell cultures from well-characterized transgenic plants transformed with 35S::GUS with and without flanking MARs and then comparing GUS specific activity in the cell lines to those of the transgenic plants from which the cell lines were derived. If cell differentiation state and proliferation rate do affect MAR function, we would expect the ratio of transgene expression (cell suspensions : plants) to be greater in MAR lines than in control lines. This turned out not to be the case. Thus, it appears that MAR function is not enhanced simply because cells in culture divide rapidly and are not differentiated. Because in animal systems the chromosomal protein HMG-I/Y has been shown to be upregulated in proliferating cells and may have a role in MAR function, we have also examined the levels of the tobacco HMG-I/Y homolog by immunoblotting. The level of this protein does not differ between primary transformant cultured cells (NT-1) and Nicotiana tabacum plants (SR-1). However, a higher molecular weight cross-reacting polypeptide was found in nuclei from the NT-1 cell suspensions but was not detected in SR-1 leaf nuclei or cell suspensions derived from the SR-1 plants. 相似文献
32.
Ascenzi R Ulker B Todd JJ Sowinski DA Schimeneck CR Allen GC Weissinger AK Thompson WF 《Transgenic research》2003,12(3):305-318
33.
Bonini C Grez M Traversari C Ciceri F Marktel S Ferrari G Dinauer M Sadat M Aiuti A Deola S Radrizzani M Hagenbeek A Apperley J Ebeling S Martens A Kolb HJ Weber M Lotti F Grande A Weissinger E Bueren JA Lamana M Falkenburg JH Heemskerk MH Austin T Kornblau S Marini F Benati C Magnani Z Cazzaniga S Toma S Gallo-Stampino C Introna M Slavin S Greenberg PD Bregni M Mavilio F Bordignon C 《Nature medicine》2003,9(4):367-369
34.
Growth, productivity, and competitiveness of introgressed weedy Brassica rapa hybrids selected for the presence of Bt cry1Ac and gfp transgenes 总被引:2,自引:0,他引:2
Halfhill MD Sutherland JP Moon HS Poppy GM Warwick SI Weissinger AK Rufty TW Raymer PL Stewart CN 《Molecular ecology》2005,14(10):3177-3189
Concerns exist that transgenic crop x weed hybrid populations will be more vigorous and competitive with crops compared with the parental weed species. Hydroponic, glasshouse, and field experiments were performed to evaluate the effects of introgression of Bacillus thuringiensis (Bt) cry1Ac and green fluorescent protein (GFP) transgenes on hybrid productivity and competitiveness in four experimental Brassica rapa x transgenic Brassica napus hybrid generations (F1, BC1F1, BC2F1 and BC2F2). The average vegetative growth and nitrogen (N) use efficiency of transgenic hybrid generations grown under high N hydroponic conditions were lower than that of the weed parent (Brassica rapa, AA, 2n = 20), but similar to the transgenic crop parent, oilseed rape (Brassica napus, AACC, 2n = 38). No generational differences were detected under low N conditions. In two noncompetitive glasshouse experiments, both transgenic and nontransgenic BC2F2 hybrids had on average less vegetative growth and seed production than B. rapa. In two high intraspecific competition field experiments with varied herbivore pressure, BC2F2 hybrids produced less vegetative dry weight than B. rapa. The competitive ability of transgenic and nontransgenic BC2F2 hybrids against a neighbouring crop species were quantified in competition experiments that assayed wheat (Triticum aestivum) yield reductions under agronomic field conditions. The hybrids were the least competitive with wheat compared with parental Brassica competitors, although differences between transgenic and nontransgenic hybrids varied with location. Hybridization, with or without transgene introgression, resulted in less productive and competitive populations. 相似文献
35.
Weissinger J 《Biotechnology advances》1989,7(3):387-399
Initial evaluation of the safety of biological products, whether manufactured by biotechnology or not, is dictated by the extent of knowledge of the biological effects in vitro, in animals, and in man at the proposed dose and duration of administration. The quantity of useful information that will be gained from an animal study is considered for each product on a case-by-case basis. This requires consideration of the availability of a relevant species. Relevance is determined by presence and relative affinity and distribution of receptors for the biological product, relative potency in induction of biological activity related to the putative mechanism of action and pharmacokinetic considerations. The impurities and immunogenic potential of the product are also considered in designing the preclinical studies. After evaluating all these factors, the residual lack of knowledge is FDA's basis for recommending specific preclinical testing. The considerations inherent in the preclinical evaluation of factors acting primarily on hematopoietic cells, erythropoietin (EPO), interleukins (IL's) and colony stimulating factors (CSF) (1) will be discussed using case examples. 相似文献
36.
Addition of constitutive c-myc expression to Abelson murine leukemia virus changes the phenotype of the cells transformed by the virus from pre-B-cell lymphomas to plasmacytomas. 下载免费PDF全文
E M Weissinger H Mischak J Goodnight W F Davidson J F Mushinski 《Molecular and cellular biology》1993,13(4):2578-2585
Abelson murine leukemia virus (A-MuLV), a retrovirus that expresses the v-abl oncogene, characteristically induces pre-B-cell lymphomas following in vivo infection of BALB/c mice or in vitro infection of suspensions of fetal liver or bone marrow cells. ABL-MYC, a retrovirus that expresses both v-abl and c-myc, induces solely plasmacytomas in BALB/c mice. To investigate how the addition of overexpression of c-myc to that of v-abl accomplishes this dramatic change in the phenotype of the cells transformed by these closely related retroviruses, we utilized helper-free A-MuLV (psi 2) and ABL-MYC (psi 2) in vitro to infect suspensions of cells from different lymphoid tissues and purified immature and purified mature B cells. As expected, A-MuLV(psi 2) induced only pre-B-cell lymphomas in vivo and in vitro when immature B cells were present. ABL-MYC(psi 2), on the other hand, produced only plasmacytomas, even when purified immature B lymphocytes were infected in vitro. Although the A-MuLV(psi 2)-induced pre-B-cell lymphomas express easily detectable levels of c-myc mRNA, maturation into more-mature forms of B lymphocytes is blocked. The constitutively overexpressed c-myc in the ABL-MYC retrovirus abrogates this block, permits maturation of infected immature B cells, and yields transformed plasma cells. 相似文献
37.
Linkage relationships of 19 enzyme loci have been examined. The chromosomal locations of eight of these loci are formally reported for the first time in this paper. These localizations should assist in the construction of additional useful chromosome marker stocks, especially since several of these enzyme loci lie in regions that were previously poorly mapped. Six loci are on the long arm of chromosome 1. The arrangement is (centromere)—Mdh4-mmm-Pgm1-Adh1-Phi-Gdh1, with about 46% recombination between Mdh4 and Gdh1.—Linkage studies with a2 and pr have resulted in the localization of four enzyme genes to chromosome 5 with arrangement Pgm2-Mdh5-Got3-a2-(centromere)-pr-Got2. Pgm2 lies approximately 35 map units distal to a2 in a previously unmapped region of the short arm of 5, beyond ameiotic.—Approximately 23% recombination was observed between Mdh4 and Pgm1 on chromosome 1, while 17% recombination occurred between Mdh5 and Pgm2 on chromosome 5. Similarly, linkages between Idh1 and Mdh1, about 22 map units apart on chromosome 8, and between Mdh2 and Idh2, less than 5 map units apart on chromosome 6, were observed. Thus, segments of chromosomes 1 and 5 and segments of 6 and 8 may represent duplications on nonhomologous chromosomes. 相似文献
38.
Dominique Robertson Arthur K. Weissinger Rhonda Ackley Sarah Glover Ronald R. Sederoff 《Plant molecular biology》1992,19(6):925-935
Stable transformation of Norway spruce tissue has been obtained following bombardment of mature somatic embryos with pRT99gus, a plasmid that contains neo coding for NPTII, and gusA, coding for -glucuronidase, both fused to the CaMV 35S promoter. At least 8 lines have been stably transformed (over 15 months in culture) following bombardment and selection on kanamycin. Polymerase chain reaction analyses showed a high frequency of cotransformation of the gusA and neo genes. The frequency of coexpression of the selected and unselected markers was 100%. DNA/DNA hybridization of one transformed line provided conclusive evidence of stable integration and showed copy numbers of over 10 plasmid sequences per genome. None of the transformed lines has remained embryogenic. 相似文献
39.
Phylogenetic inference under the pure drift model 总被引:1,自引:1,他引:0
When pairwise genetic distances are used for phylogenetic reconstruction,
it is usually assumed that the genetic distance between two taxa contains
information about the time after the two taxa diverged. As a result, upon
an appropriate transformation if necessary, the distance usually can be
fitted to a linear model such that it is expressed as the sum of lengths of
all branches that connect the two taxa in a given phylogeny. This kind of
distance is referred to as "additive distance." For a phylogenetic tree
exclusively driven by random genetic drift, genetic distances related to
coancestry coefficients (theta XY) between any two taxa are more suitable.
However, these distances are fundamentally different from the additive
distance in that coancestry does not contain any information about the time
after two taxa split from a common ancestral population; instead, it
reflects the time before the two taxa diverged. In other words, the
magnitude of theta XY provides information about how long the two taxa
share the same evolutionary pathways. The fundamental difference between
the two kinds of distances has led to a different algorithm of evaluating
phylogenetic trees when theta XY and related distance measures are used.
Here we present the new algorithm using the ordinary- least-squares
approach but fitting to a different linear model. This treatment allows
genetic variation within a taxon to be included in the model. Monte Carlo
simulation for a rooted phylogeny of four taxa has verified the efficacy
and consistency of the new method. Application of the method to human
population was demonstrated.
相似文献
40.