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1.
J Barciszewski J Jurczak S Porowski T Specht V A Erdmann 《Acta biochimica Polonica》1999,46(1):133-144
This review summarizes data on the structure and properties of water under normal conditions, at high salt concentration and under high pressure. We correlate the observed conformational transitions in nucleic acids with changes in water structure and activity, and suggest a mechanism of conformational transitions of nucleic acid involving these changes. We conclude that the Z-DNA form is induced only at low water activity caused by high salt concentrations and/or high pressure. 相似文献
2.
Luc Giasson Charles A. Specht Craig Milgrim Charles P. Novotny Robert C. Ullrich 《Molecular & general genetics : MGG》1989,218(1):72-77
Summary An A mating-type allele (A4) was isolated by walking the chromosome from the closely linked PAB1 gene. A cosmid clone containing the A1 allele isolated from the walk was used as a probe to recover the A1 allele from another cosmid library. Cosmids encoding mating-type activity were identified by transforming Schizophyllum cells and screening for activation of A-regulated development. Putative mating-type transformants were confirmed in mating tests and genetic analyses of progeny. The identity of the specific alleles isolated was demonstrated by showing that their effectiveness in transforming for mating type is limited to recipient strains possessing an A allele different from the one encoded by the cloned sequences. Transforming DNA is active in trans, suggesting that A encodes a diffusible product. Restriction mapping shows that A1 and A4 are coded in the same physical region of the genome, but within a subregion that contains extensive sequence divergence. In addition, Southern analyses show that there is only one copy of A1 or A4 per haploid genome, and that they do not cross-hybridize to one another or to any of the other A alleles. A1 and A4 were subcloned as 2.8 and 1.2 kb fragments, respectively, retaining in transformation all the mating-type activity demonstrated of the original cosmids. 相似文献
3.
G. J. Muehlbauer P. E. Staswick J. E. Specht G. L. Graef R. C. Shoemaker P. Keim 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1991,81(2):189-198
Summary A molecular marker analysis of a near-isogenic line (NIL), its donor parent (DP), and its recurrent parent (RP) can provide information about linkages between molecular markers and a conventional marker introgressed into the NIL. If the DP and RP possess different alleles for a given molecular marker, and if the NIL possesses the same allele as the DP, then it is reasonable to presume a linkage between that molecular marker and the introgressed marker. In this study, we examined the utility of RFLPs as molecular markers for the NIL genemapping approach. The allelic status of fifteen RFLP loci was determined in 116 soybean RP/NIL/DP line sets; 66 of the Clark RP type and 50 of the Harosoy RP type. Of the 1740 possible allelic comparisons (116 NILs x 15 RFLP loci), 1638 were tested and 462 (33.9%) of those were informative (i.e., the RP and DP had different RFLP alleles). In 15 (3.2%) of these 462 cases the NIL possessed the DP-derived RFLP allele, leading to a presumption of linkage between the RFLP locus and the introgressed conventional marker locus. Two presumptive linkages, pK-3 — and pK-472 — Lf
i, were subsequently confirmed by cosegregation linkage analysis. Although not yet confirmed, two other associations, pk-7 ab and pK-229 — y
9 seemed to be plausible linkages, primarily because the pk-7 — ab association was detected in two independently derived NILs and both markers of the pK-229 — y
9 association were known to be linked to Pb. The data obtained in this investigation indicated that RFLP loci were useful molecular markers for the NIL gene-mapping technique.Published as Paper no. 9101, Journal Series, Nebraska Agric. Res. Div. Project no. 12-091. Research partially funded by a grant from the Nebraska Soybean Development, Utilization, and Marketing Board 相似文献
4.
Targeting of T7 RNA polymerase to tobacco nuclei mediated by an SV40 nuclear location signal 总被引:9,自引:0,他引:9
Michael W. Lassner Aubrey Jones Steve Daubert Luca Comai 《Plant molecular biology》1991,17(2):229-234
We have expressed two T7 RNA polymerase genes by electroporation into tobacco protoplasts. One of the genes was modified by inserting nucleotides encoding a viral nuclear localization signal (NLS) from the large T antigen of SV40. Both T7 RNA polymerase genes directed synthesis of a ca. 100 kDa protein in the electroporated protoplasts. T7 RNA polymerase activity was detected in extracts of protoplasts electroporated with both genes. Immunofluorescence analysis of these protoplasts indicated that only the polymerase carrying the NLS accumulated in the cell nucleus. These experiments suggest that mechanisms involved in the transport from the cytoplasm to the nucleus are similar in plant and animal cells. This system demonstrates the feasibility of T7 RNA polymerase-based approaches for the high-level expression of introduced genes in plant cells. 相似文献
5.
Alfredo Munoz-Rivas Charles A. Specht Bruce J. Drummond Eunice Froeliger Charles P. Novotny Robert C. Ullrich 《Molecular & general genetics : MGG》1986,205(1):103-106
Summary Protoplasts of aSchizophyllum commune tryptophan auxotroph (trp1), deficient in indole-3-glycerol phosphate synthetase (IGPS), were transformed to trp+ with plasmid DNA containing the SchizophyllumTRP1 sequence. Efficiencies up to 30 transformants per microgram of plasmid DNA were obtained. Southern blots reveal that the
transforming DNA is integrated in chromosomal DNA. The trp+ phenotype of transformants is stable in meiosis and mitosis. Transformants possess IGPS activity comparable to wild-type
cells. 相似文献
6.
The frequency of ultraviolet(UV)-induced mutations drops rapidly whenEscherichia coli Hcr+ cells (strains WP-2 Hcr+; B/r) are incubated on phosphate-buffered agar (PBA), but is reduced only slightly if chloroquine or quinacrine are incorporated into the medium. The excision-deficient WP-2 Hcr– strain shows little reduction in the number of mutants when incubated on PBA. During postirradiation incubation on PBA, cell viability was relatively unaffected by the presence of the chemicals in the PBA (25 g/ml quinacrine; 50 g/ml chloroquine). When cells were given optimal doses of photoreactivating light, no further decline in mutations was obtained during subsequent incubation on PBA. Approximately 64% of the mutants seen when cells are treated with UV-PBA-chloroquine and 90% seen with UV-PBA-quinacrine can be repaired if cells are incubated on PBA. When these chemicals were added to the PBA, both excision-proficient strains (WP-2 Hcr+; B/r) demonstrated a marked reduction in the repair of UV-induced mutations to streptomycin resistance. Our results indicate that these chemicals interfere with the excision of UV-induced pyrimidine dimers, a process that normally occurs during postirradiation incubation on PBA. 相似文献
7.
8.
9.
Linkage analysis of seven kindreds with the X-linked lymphoproliferative syndrome (XLP) confirms that the XLP locus is near DXS42 and DXS37 总被引:5,自引:0,他引:5
James C. Skare Helen L. Grierson John L. Sullivan Robert L. Nussbaum David T. Purtilo Bakary S. Sylla Gilbert M. Lenon Dorothy S. Reilly Bradley N. White Aubrey Milunsky 《Human genetics》1989,82(4):354-358
Summary Analysis of seven kindreds indicates that the XLP locus exhibits 1% recombination with DXS42 (lod = 17.5) and no recombination with DXS37 (lod = 13.3). 相似文献
10.
Ivan Valiela Joseph Costa Kenneth Foreman John M. Teal Brian Howes David Aubrey 《Biogeochemistry》1990,10(3):177-197
Anthropogenic activities on coastal watersheds increase nutrient concentrations of groundwater. As groundwater travels downslope it transports these nutrients toward the adjoining coastal water. The resulting nutrient loading rates can be significant because nutrient concentrations in coastal groundwaters may be several orders of magnitude greater than those of receiving coastal waters. Groundwater-borne nutrients are most subject to active biogeochemical transformations as they course through the upper 1 m or so of bottom sediments. There conditions favor anaerobic processes such as denitrification, as well as other mechanisms that either sequester or release nutrients. The relative importance of advective vs. regenerative pathways of nutrient supply may result in widely different rates of release of nutrients from sediments. The relative activity of denitrifiers also may alter the ratio of N to P released to overlying waters, and hence affect which nutrient limits growth of producers. The consequences of nutrient (particularly nitrate) loading include somewhat elevated nutrient concentrations in the watercolumn, increased growth of macroalgae and phytoplankton, reduction of seagrass beds, and reductions of the associated fauna. The decline in animals occurs because of habitat changes and because of the increased frequency of anoxic events prompted by the characteristically high respiration rates found in enriched waters. 相似文献