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911.
Werner Selbitschka Walter Arnold Ursula B. Priefer Thomas Rottsch?fer Michael Schmidt Reinhard Simon Alfred Pühler 《Molecular & general genetics : MGG》1991,229(1):86-95
Summary DNA fragments carrying the recA genes of Rhizobium meliloti and Rhizobium leguminosarum biovar viciae were isolated by complementing a UV-sensitive recA
–
Escherichia coli strain. Sequence analysis revealed that the coding region of the R. meliloti recA gene consists of 1044 by coding for 348 amino acids whereas the coding region of the R. leguminosarum bv. viciae recA gene has 1053 bp specifying 351 amino acids. The R. meliloti and R. leguminosarum bv. viciae recA genes show 84.8% homology at the DNA sequence level and of 90.1% at the amino acid sequence level. recA
– mutant strains of both Rhizobium species were constructed by inserting a gentamicin resistance cassette into the respective recA gene. The resulting recA mutants exhibited an increased sensitivity to UV irradiation, were impaired in their ability to perform homologous recombination and showed a slightly reduced growth rate when compared with the respective wild-type strains. The Rhizobium recA strains did not have altered symbiotic nitrogen fixation capacity. Therefore, they represent ideal candidates for release experiments with impaired strains.The accession numbers: X59956 R. LEGUMINOSARUM REC A ALAS-DNA; X59957 R. MELITOTI REC A ALAS-DNA 相似文献
912.
Helmut Bäumlein Wout Boerjan Istvan Nagy Reinhard Panitz Dirk Inzé Ulrich Wobus 《Molecular & general genetics : MGG》1991,225(1):121-128
Summary We have previously isolated a legumin gene LeB4 from Vicia faba and shown that a 4.7 kb DNA fragment containing the gene leads to seed-specific expression in transgenic tobacco plants. Here we report that the 2.4 kb upstream sequence alone, when fused to either the neomycin phosphotransferase II (nptII) gene or the -glucuronidase (uidA) gene, leads to high enzyme levels in transgenic seeds of both tobacco and Arabidopsis. -Glucuronidase (GUS) activity is especially intense in the cotyledons fading out towards the embryonal root tip, a result confirmed by in situ hybridization. Staining of endosperm cells is consistent in both species. Analysis of a series of promoter deletion mutants fused to the nptII gene and introduced into tobacco plants revealed that about 1 kb of 5-flanking sequence is sufficient for high-level expression but indirect evidence suggests the presence of weak positive regulatory elements further upstream. Deletions leaving only 0.2 kb of upstream sequence reduce enzyme levels to less than 10%. A deletion which destroys the legumin box with its seed protein gene-specific CATGCATG motif has no obvious effects on expression levels. 相似文献
913.
Iron deficiency chlorosis (FeDC) is a common disorder for sorghum [Sorghum bicolor (L.) Moench] grown on alkaline calcareous soils. Four sorghum genotypes were grown in growth chambers on a low Fe (1.3 g/g DTPA-extractable), alkaline (pH 8.0), calcareous (3.87% CaCO3 equivalent) Aridic Haplustoll to determine effects of different soil temperatures (12, 17, 22 and 27°C at a constant 27°C air temperature) on various root and shoot growth traits and development of FeDC. As soil temperature increased, leaf chlorosis became more severe, and shoot and root dry weights, root lengths, and leaf areas increased markedly. Shoot/root ratios, shoot weight/root length, leaf area/shoot weight and leaf area/root weight and root length also increased while root length/root weight decreased as soil temperature increased. Severe FeDC developed in all genotypes even though genotypes had previously shown different degrees of resistance to FeDC. Genotypes differed in most growth traits, especially dry matter yields, root lengths, and leaf areas, but most traits did not appear to be related to genotype resistance to FeDC. The most FeDC resistant genotype had the slowest growth rate and this may be a mechanism for its greater resistance to FeDC. 相似文献
914.
Guido Kroemer Arno Helmberg Alain Bernot Charles Auffray Reinhard Kofler 《Immunogenetics》1991,33(1):42-49
Similar to the Igh-V multigene family, the human or mouse Igk-V repertoirer is a distorted continuum of homologous genes that may be grouped into families displaying >80% nucleic acid sequence similarity among their members. systematic interspecies sequence comparisons reveal that most human Igk-V gene families exhibit clear homology to mouse Ogk-V families (sequence similarity >74%). A hypothetical phylogenetic tree of Igk-V genes predicts that a minimum of seven Igk-V genes/families predate mammalian radiation. In two cases, several interrelated mouse Igk-V families exhibit phylogenetic equidistance with just one human Igk-V family, implying a more pronounced divergence for the elevated number of Igk-V gene families in the mouse. Mouse-human Igk-V comaprisons, moreover, illustrate how expansion, contraction, and perhaps deletion of Igk-V gene families shape the Igk-V repertoire during mammalian evolution. 相似文献
915.
Jon Vidar Helvik Dag Oscar Oppen-Berntsen Per Robert Flood Bernt Theodor Walther 《Development genes and evolution》1991,200(4):180-187
Summary The halibut hatching gland (HG) cells are first observed as a cellular disc in front of the embryonic head around the midpoint of intra ovo development. The disc is subsequently transformed into a loop of increasing diameter as the HG cells migrate over the anterior part of the yolk sac. When the HG disc is transformed into a loop, the density of HG cells is highest at the migratory front. Some HG cells lag behind the migrating front at the early stages of HG development. At maturity, all cells are contained in a narrow belt which is about 10 cells wide. The HG belt structure consists of a monolayer of HG cells, and is maintained while the cells migrate between the two epidermal cell layers. Migration is halted about 2 days before normal hatching when the HG cells reach a destination at about a right angle to on the embryonic axis. Under the scanning electron microscope, the differentiating HG cells protrude as a ridge the yolk sac surface. The HG cells immunostain with antiserum to hatching enzyme when the HG is observed as a crescent structure around the embryonic head. By counting the number of immunostaining cells in composite photos of the entire yolk sac membrane, we found that the HG belt consists of approximately 2000 secretory cells at maturity. This cell number stays fairly constant throughout the period of HG cell migration. Accordingly, mitoses of the halibut HG cells have generally ceased prior to morphogenesis, and cytodifferentiation is already quite advanced when cell migration starts.
Offprint requests to: J.V. Helvik 相似文献
916.
Dorothee Heuermann Peter Roggentin Reinhard G. Kleineidam Roland Schauer 《Glycoconjugate journal》1991,8(2):95-101
The sialidase secreted byClostridium chauvoei NC08596 was purified to apparent homogeneity by ion-exchange chromatography, gel filtration, hydrophobic interaction-chromatography, FPLC ion-exchange chromatography, and FPLC gel filtration. The enzyme was enriched about 10 200-fold, reaching a final specific activity of 24.4 U mg–1. It has a relatively high molecular mass of 300 kDa and consists of two subunits each of 150 kDa. The cations Mn2+, Mg2+, and Ca2+ and bovine serum albumin have a positive effect on the sialidase activity, while Hg2+, Cu2+, and Zn2+, chelating agents and salt decrease enzyme activity. The substrate specificity, kinetic data, and pH optimum of the enzyme are similar to those of other bacterial sialidases.Abbreviations FPLC
fast protein liquid chromatography
- NCTC
National Collection of Type Cultures
- ATCC
American Type Culture Collection
- MU-Neu5Ac
4-methylumbelliferyl--d-N-acetylneuraminic acid
- buffer A
0.02m piperazine, 0.01m CaCl2, pH 5.5
- buffer B
0.02m piperazine, 0.01m CaCl2, 1.0m NaCl, pH 5.5
- buffer C
0.1m sodium acetate, 0.01m CaCl2, pH 5.5
- SDS
sodium dodecyl sulfate
- PAGE
polyacrylamide gel electrophoresis
- Neu5Ac
N-acetylneuraminic acid
- BSM
bovine submandibular gland mucin
- GD1a
IV3Neu5Ac, II3Neu5Ac-GgOse4Cer
- GM1
II3Neu5Ac-GgOse4Cer
- MU-Neu4,5Ac2
4-methylumbelliferyl--d-N-acetyl-4-O-acetylneuraminic acid
- TLC
thin-layer chromatography
- HPTLC
high performance thin-layer chromatography
- EDTA
ethylenediamine tetraacetic acid
- EGTA
ethylene glycol bis(2-aminoethyl-ethen)-N,N,N,N-tetraacetic acid
- BSA
bovine serum albumin
- Neu5Ac2en
2-deoxy-2,3-didehydro-N-acetylneuraminic acid
- IEF
isoelectric focusing
- IEP
isoelectric point 相似文献
917.
A Gal1-4GlcNAc (2-6)-sialyltransferase from human liver was purified 34 340-fold with 18% yield by dye chromatography on Cibacron Blue F3GA and cation exchange FPLC. The enzyme preparation was free of other sialyltransferases. It did not contain CMP-NeuAc hydrolase, protease, or sialidase activity, and was stable at –20°C for at least eight months. The donor substrate specificity was examined with CMP-NeuAc analogues modified at C-5 or C-9 of theN-acetylneuraminic acid moiety. Affinity of the human enzyme for parent CMP-NeuAc and each CMP-NeuAc analogue was substantially higher than the corresponding Gal1-4GlcNAc (2-6)-sialyltransferase from rat liver.Abbreviations FPLC
fast protein liquid chromatography
- NeuAc
5-N-acetyl-d-neuraminic acid
- 9-amino-NeuAc
5-acetamido-9-amino-3,5,9-trideoxy-d-glycero-2-nonulosonic acid
- 9-acetamido-NeuAc
5,9-diacetamido-3,5,9-trideoxy-d-glycero--d-2-nonulosonic acid
- 9-benzamido-NeuAc
5-acetamido-9-benzamido-3,5,9-trideoxy-d-glycero--d-galacto-2-nonulosonic acid
- 9-fluoresceinyl-NeuAc
9-fluoresceinylthioureido-NeuAc
- 5-formyl-Neu
5-formyl--d-neuraminic acid
- 5-aminoacetyl-Neu
5-aminoacetyl--d-neuraminic acid
- CMP-NeuAc
cytidine-5-monophospho-N-acetylneuraminic acid
- GM1
Gal1-3GalNAc1-4(NeuAc2-3)Gal1-4Glc-ceramide
- ST
sialyltransferase
- DTE
1,4-dithioerythritol
Enzyme: Gal1-4GlcNAc (2-6)-sialyltransferase, EC 2.4.99.1. 相似文献
918.
Acetate is effectively taken up by whole cells of Corynebacterium glutamicum via a specific carrier with a pH optimum of 8. The K
m of acetate uptake was 50 μM and the V
max 25–35 nmol/mg dw min. The activation energy was determined to be 70 kJ/mol. Acetate uptake was competitively inhibited by
propionate with a K
i of about 30 μM and blocked by addition of sulfhydryl reagents. The transport activity was clearly dependent on the membrane
potential, but independent of the presence of Na+-ions. It is concluded that uptake of acetate proceeds by a secondary, proton coupled mechanism. 相似文献
919.
Glenn Gladys M. Daniel Lambert N. Choyke Peter Linehan W. Marston Oldfield Edward Gorin Michael B. Hosoe Shigeto Latif Farida Weiss Gary Walther McClellan Lerman Michael I. Zbar Berton 《Human genetics》1991,87(2):207-210
Summary As part of an attempt to locate the von Hippel-Lindau locus (VHL) on chromosome 3, we evaluated 41 families with von Hippel-Lindau disease from the United States and Canada. One large family was identified whose disease phenotype was distinct from typical VHL. The most common disease manifestation was pheochromocytoma occuring in 57% (27/47) of affected family members. Few (4/47) affected family members had symptomatic spinal or cerebellar hemangioblastomas; no affected family member had renal cell carcinoma (0/47) or pancreatic cysts (0/24). Previously, genetic analysis demonstrated that the disease manifestations in this family were linked to RAF1 and D3S18, markers shown to be linked to typical VHL. These results suggest that there are mutant alleles at the VHL locus associated with distinct tissue specificities. 相似文献
920.
Comparative analysis of UV-induced mutability of ten different codon units in position 211 of the Escherichia coli trpA gene 总被引:1,自引:0,他引:1
Summary To study the influence of the local base, composition upon UV-induced mutability the reversion frequencies of ten trpA mutants with known codon sequences at position 211 were compared. Comparison of mutant strains reverting by the same base substitution type but with different dipyrimidinic, sequences reveals the mutagenic character of the pyrimidine-pyrimidine (6-4) photoproduct. The codons GAC and GAT, both reverting by AT-GC transitions and AT-CG transversions in the middle position and harboring the dipyrimidinic sequence CT in the opposite strand, differ, in their reversion frequencies sixfold. This difference can only be due to the influence of the different bases in the third codon position upon the mutability of adjacent second bases. 相似文献