共查询到20条相似文献,搜索用时 31 毫秒
1.
Parshikov IA Freeman JP Williams AJ Moody JD Sutherland JB 《Applied microbiology and biotechnology》1999,52(4):553-557
Cultures of the fungi Aspergillus niger, Cunninghamella verticillata, and Penicillium simplicissimum, grown in a sucrose/peptone medium, transformed N-acetylphenothiazine to N-acetylphenothiazine sulfoxide (from 13% to 28% of the total) and phenothiazine sulfoxide (from 5% to 27%). Phenothiazin-3-one
(4%) and phenothiazine N-glucoside (4%) were also produced by C. verticillata. The probable intermediate, phenothiazine, was detected only in cultures of P. simplicissimum (6%).
Received: 15 January 1999 / Received revision: 7 May 1999 / Accepted: 21 May 1999 相似文献
2.
S. Masci R. D’Ovidio D. Lafiandra D. D. Kasarda 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,100(3-4):396-400
Received: 25 May 1999 / Accepted: 22 June 1999 相似文献
3.
Ashkenazy R Yannai S Rahman R Rabinovitz E Gottlieb L 《Applied microbiology and biotechnology》1999,52(4):608-611
Spent Saccharomyces cerevisiae cells from a beer fermentation process were evaluated for lead cation sorption. The crude biomass was washed with water and
acetone prior to any other treatment. Although the washed biomass showed substantial lead ion sorption it was susceptible
to microbial spoilage. Different aldehydes were tested as chemical fixation agents; however, most of them caused drastic lowering
of the metal uptake capacity. However, benzaldehyde was not only an excellent fixation agent, but the biomass treated with
it also retained its original lead sorption capacity. A mechanism for the fixation process is suggested.
Received: 11 January 1999 / Received revision: 26 April 1999 / Accepted: 1 May 1999 相似文献
4.
Culebras E Martínez E Carnero A Malpartida F 《Molecular & general genetics : MGG》1999,262(4-5):730-737
In a search for activators of secondary metabolism we isolated a 12.6-kb DNA fragment from a genomic library of Streptomyces ambofaciens NRRL 2240 (the spiramycin producer ). Sequencing of 6 kb of the cloned fragment revealed a cluster of four ORFs (ORF1–4)
whose deduced products showed similarities to those of other genes involved in polyketide biosynthesis, including a pathway-specific
regulatory gene of the SARP family. The results of insertional inactivation of some of the cloned genes clearly indicate that
the isolated cluster does not code for spiramycin production, suggesting that some other polyketide compound might well be
produced by this strain.
Received: 14 May 1999 / Accepted: 28 July 1999 相似文献
5.
P. Wahl P. Walser-Volken K. Laumen M. Kittelmann O. Ghisalba 《Applied microbiology and biotechnology》1999,53(1):12-18
Rhodococcus globerulus K1/1 was found to express an inducible (S)-specific N-acetyl-2-amino-1-phenyl-4-pentene amidohydrolase. Optimal bacterial growth and amidohydrolase expression were both observed
at about pH 6.5. Purification of the enzyme to a single band in a Coomassie blue-stained SDS-PAGE gel was achieved by nucleic
acid and ammonium sulfate precipitation of Rhodococcus globerulus K1/1 crude extract and column chromatography on TSK Butyl-650(S) Fractogel and Superose 12HR. The amidohydrolase was purified to a homogeneity leading to a tenfold increase of the specific
activity with a recovery rate of 65%. At pH 7.0 and 23 °C the enzyme showed no loss of activity after 30 days incubation.
The amidohydrolase was stable up to 55 °C. The enzyme was inhibited strongly only by 10 mM Zn2+ among the tested metal cations and was inhibited 100% by 0.01 mM phenylmethanesulfonyl fluoride. The molecular weight of
the native enzyme was estimated to be 92 kDa by gel filtration and 55 kDa by SDS-PAGE, suggesting a homodimeric structure.
Received: 8 February 1999 / Received revision: 3 May 1999 / Accepted: 7 May 1999 相似文献
6.
Isolation and characterization of a β-lactamase (EC 3.5.2.6)-free, penicillin amidase (penicillin amidohydrolase, EC 3.5.1.11)-producing
organism is reported. The test strain was isolated by an enrichment technique with a substrate other than penicillins. The
isolated strain belongs to the genus Alcaligenes. Phenylacetic acid was found to be the inducer of penicillin amidase. The amidase has a broad substrate spectrum. It is very
active against penicillin G and semisynthetic cephalosporins, whereas penicillin V and semisynthetic penicillins acted moderately
as a substrate. Immobilized cells of Alcaligenes sp. were shown to act as a reversible enzyme.
Received: 28 April 1999 / Accepted: 18 May 1999 相似文献
7.
Local therapy with interleukin-2 (IL-2) and other cytokines may be a very effective way to treat cancer. This was the theme
of the First Symposium on Local Cytokine Therapy of Cancer: Interleukin-2, Interferons and Related Cytokines, in Hamburg,
29 April–1 May 1999. The abstracts are published in Anticancer Research 19: 1995–2016 (1999) [1]. Here we present a report.
Received: 28 October 1999 / Accepted: 2 December 1999 相似文献
8.
The centromere/kinetochore complex is a chromosomal assembly that mediates chromosome motility and mitotic regulation by interacting
with microtubules of the mitotic spindle apparatus. Centromere protein A (CENP-A) is a histone H3 homolog that is concentrated
in the chromatin of the inner kinetochore plate of human chromosomes. To identify DNA sequences associated with the inner
kinetochore plate, we used anticentromere autoantibodies to immunoprecipitate CENP-A associated chromatin selectively from
Indian muntjac fibroblasts. DNA was cloned from immunoprecipitated CENP-A- associated chromatin and characterized by DNA sequence
and hybridization analyses. A novel centromeric satellite DNA sequence was identified and shown by fluorescence in situ hybridization
analysis to be present at all centromeres of the Indian muntjac. This satellite DNA constitutes a 972 bp monomer repeat and
shows partial homology with satellite II DNA of the white-tailed deer. Southern blot analysis of muntjac genomic DNA suggests
that this satellite DNA is present in repetitive tandem arrays and contains complex internal arrangements. In conjunction
with previous work showing the association of CENP-A with human α-satellite DNA, we conclude that the mammalian inner kinetochore
plate contains a unique form of chromatin that contains CENP-A in association with complex satellite DNA.
Received: 18 May 1999; in revised form: 5 July 1999 / Accepted: 20 July 1999 相似文献
9.
This study examined three aspects of protogynous sex change in Lythrypnus dalli (Gobiidae): (1) social influences on the rate of sex change, (2) the sequence of behavioural changes, and (3) neuroendocrine
changes. Social groups consisted of either four females, or four females with a male who was subsequently removed. Sex change
occurred most rapidly in male- removed groups when the sex changer was larger than other females. Sex changers in female only
groups and sex changers not larger than other females in male-removed groups changed sex at similar rates. These differences
may be explained by two factors that affect dominance: prior knowledge of the social group and greater size. Sex changers
were dominant to other females prior to male removal, and larger sex changers increased displacement rates three-fold immediately
after male removal. Sex changers in the other groups did not show this increase in displacements. This early establishment
of dominance accounts for the overall difference in the rate of sex change. Prior to spawning, however, all sex changers increased
displacements and performed male-typical displays. Arginine vasotocin-immunoreactive forebrain cells of sex changers were
similar in size to field-collected males, and larger than field-collected females. Previously nesting males also changed sex
in male-only groups, but at slow rates. These data are combined with those of existing studies to generate an integrative
model of sex change in this goby.
Received: 17 March 1999 / Received in revised form: 15 May 1999 / Accepted: 28 May 1999 相似文献
10.
IGLESIAS J.; CASTILLEJO J.; PARAMA R.; MASCATO R.; LOMBARDIA M.J. 《Journal of Molluscan Studies》2000,66(2):171-176
Laboratory research is reported in which eggs of the pest slugDeroceras reticulatum were incubated on filter paper moistenedwith solutions of cupric sulphate, aluminium sulphate, ferricchloride and zinc sulphate at different concentrations. Afterfour or more days exposure, the median lethal doses (LD50) werebelow 10 mg metal ion/cm2 for the four metals tested. Coppershowed the highest toxicity with LD50 values below 5 mg metalion/cm2. (Received 25 May 1999; accepted 1 September 1999) 相似文献
11.
Eidus LK 《Radiation and environmental biophysics》2000,39(3):189-195
A novel theory is proposed regarding the action of ionizing radiation in the range of very low doses. The basic premise of
the theory presented is that the low-dose effect cannot be explained by direct damage to the DNA (as has generally been assumed)
and that effects on cellular membranes should be considered instead. Low-dose radiation damaging the plasma membrane decreases
the concentration of low-molecular weight compounds (LMWC) inside the cell, which through an unspecific mechanism induces
an activation of all enzymes. The mechanism described here has been well substantiated. The changes in the intracellular contents
of LMWC and the increase of pHin cause chromatin rearrangements, alterations in DNA folding and finally, if the latter are strong enough, expression of various
”silent” genes including repair enzyme genes.
Received: 2 February 1999 / Accepted: 15 May 2000 相似文献
12.
Metal-induced expressing of mammal Metallothionein-1 gene in cyanobacteria to promote cadmium-binding preferences 总被引:1,自引:0,他引:1
X. -X. Guo D. -J. Shi X. -D. Xu Y. -X. Ouyang B. -G. Ru 《Applied microbiology and biotechnology》1999,52(6):806-810
The metal(zinc)-inducible smtA gene promoter (smt O-P) from cyanobacteria was applied for the expression of mouse MT-1 cDNA in the filamentous cyanobacterium Anabaena sp. PCC 7120 to enhance its metal-binding capability and to change its main binding specificity from zinc to cadmium. Shuttle
expression vector pKT-MRE transformed the cyanobacterial cells by triparent conjugal transfer. Positive clones were screened
and identified by streptomycin, DNA dot blot, SDS-PAGE and Western blot analysis. Photosynthetic oxygen evolution and metal
atom absorption indicated that under the cadmium stress the metal-induced expression of foreign mMT-1 doubled their cadmium
resistance and developed cells showing a much higher preference to absorb cadmium other than zinc in medium. The cadmium content
in cell extract rose from 11% to 36%, and the cadmium cleared from media by transgenic cells rose from 18% to 62%. There was
only a slight enhancement for zinc binding in the wild or transgenic type.
Received: 1 March 1999 / Received last revision: 9 July 1999 / Accepted: 1 August 1999 相似文献
13.
Screening of ectomycorrhizal fungi for degradation of polycyclic aromatic hydrocarbons 总被引:6,自引:0,他引:6
A. Braun-Lüllemann A. Hüttermann A. Majcherczyk 《Applied microbiology and biotechnology》1999,53(1):127-132
Ectomycorrhizal fungi belonging to 16 species (27 strains) were tested for their ability to degrade polycyclic aromatic hydrocarbons
(PAHs): phenanthrene, chrysene, pyrene and benzo[a]pyrene. Cultivated on a complex liquid medium, most of the fungi tested were able to metabolise these compounds. Approximately
50% of the benzo[a]pyrene was removed by strains of Amanita excelsa, Leccinum versipelle, Suillus grevillei, S. luteus, and S. variegatus during a 4-week incubation period. The same amount of phenanthrene was also metabolised by A. muscaria, Paxillus involutus, and S. grevillei. The degradation of the other two PAHs was, for the most part, less effective. Only S. grevillei was able to remove 50% of the pyrene, whereas Boletus edulis and A. muscaria removed 35% of the chrysene.
Received: 12 April 1999 / Received revision: 27 May 1999 / Accepted: 28 May 1999 相似文献
14.
Whisker-mediated transformation of embryogenic callus of maize 总被引:4,自引:0,他引:4
The present study was designed to establish embryogenic callus as a target tissue for whisker-mediated transformation of
maize (Zea mays L.). Silicon carbide whiskers were used to deliver the bar and uidA (GUS) genes into embryogenic maize callus. Samples of osmotically-treated Type II callus were vigorously agitated in the
presence of whiskers and plasmid DNA using a standard laboratory vortex or a modified dental amalgamator. On average, three
transgenic callus lines were obtained per 100 samples treated. Plants were regenerated from several GUS-expressing callus
lines and DNA analyses confirmed stable integration and inheritance. As with other direct DNA delivery methods involving embryogenic
maize callus, integration patterns of the inserted DNA appeared to be complex. Although currently less efficient than microparticle
bombardment on a per target basis, whisker-mediated transformation of embryogenic callus represents a viable method for transgenic
maize production.
Received: 14 May 1999 / Revision received: 11 October 1999 / Accepted: 11 October 1999 相似文献
15.
J.-C. Wang M. Sakakibara J.-Q. Liu T. Dairi N. Itoh 《Applied microbiology and biotechnology》1999,52(3):386-392
The gene encoding phenylacetaldehyde reductase (PAR), a useful biocatalyst for producing chiral alcohols, was cloned from
the genomic DNA of the styrene-assimilating Corynebacterium sp. strain ST-10. The gene contained an opening reading frame consisting of 1,158 nucleotides corresponding to 385 amino
acid residues. The subunit molecular weight was calculated to be 40,299, which was in agreement with that determined by polyacrylamide
gel electrophoresis. The enzyme was sufficiently expressed in recombinant Escherichia coli cells for practical use and purified to homogeneity by three-column chromatography steps. The predicted amino acid sequence
displayed only 20–29% identity with zinc-containing, NAD+-dependent, long-chain alcohol dehydrogenases. Nevertheless, the probable NAD+- and zinc-binding sites are conserved although one of the three catalytic zinc-binding residues of the zinc-containing, long-chain
alcohol dehydrogenases was substituted by Asp in PAR. The protein contains 7.6 mol zinc/mol tetramer. Therefore, the enzyme
was considered as a new member of zinc-containing, long-chain alcohol dehydrogenases with a particular and broad substrate
specificity.
Received: 5 March 1999 / Received last revision: 10 May 1999 / Accepted: 16 May 1999 相似文献
16.
Two acyl-CoA-binding-protein (ACBP) isoforms were isolated from proembryogenic masses of Digitalis lanata Ehrh. by column chromatography and preparative HPLC. The ACBPs had molecular masses of 9926 and 9997 Da, respectively. Partial
sequence data indicated high similarity to each other and to ACBPs of other plant species such as Ricinus communis, Brassica napus and Arabidopsis thaliana. The isolated ACBPs bound palmitoyl-CoA with high affinity as determined by isoelectric-point shift.
Received: 29 May 1999 / Accepted: 28 August 1999 相似文献
17.
An analysis of dielectric spectra, obtained by computer modeling, of spherical eukaryotic cells (lymphocytes in particular)
is presented. The number of fitting parameters required to describe these spectra is determined. The influence of parameter
variation on the spectral shape is illustrated.
Received: 27 May 1999 / Revised version: 24 January 2000 / Accepted: 26 January 2000 相似文献
18.
Charles Lee Dean R. Court Charles Cho Jennifer L. Haslett Chyi-Chyang Lin 《Journal of molecular evolution》1997,44(3):327-335
Based on sequence analyses of 17 complete centromeric DNA monomers from ten different deer species, a model is proposed for
the genesis, evolution, and genomic organization of cervid satellite I DNA. All cervid satellite I DNA arose from the initial
amplification of a 31-bp DNA sequence. These 31-bp subrepeats were organized in a hierarchical fashion as 0.8-kb monomers
in plesiometacarpalia deer and 1-kb monomers in telemetacarpalia deer. The higher-order repeat nature of cervid centromeric
satellite DNA monomers accounts for their high intragenomic and intraspecific sequence conservation. Such high intraspecific
sequence conservation validates the use of a single cervid satellite I DNA monomer from each deer species for interspecific
sequence comparisons to elucidate phylogenetic relationships. Also, a specific 0.18-kb tandem duplication was observed in
all 1-kb monomers, implying that 1-kb cervid satellite I DNA monomers arose from an unequal crossover event between two similar
0.8-kb ancestral DNA sequences.
Received: 28 May 1996 / Accepted: 24 October 1996 相似文献
19.
On-line monitoring of NAD(P)H fluorescence and 2D fluorescence spectroscopy was performed with Enterobacter aerogenes, a bacterium sensitive to oxygen availability. The organism was grown in a reactor under low and high dissolved oxygen concentrations
and circulated through a bypass attached to the reactor. Under low dissolved oxygen concentration in the reactor, NAD(P)H
fluorescence in the reactor and the bypass showed a deviation, but not when the dissolved oxygen level in the reactor was
high. The pattern of growth curves was identical under low and high oxygen levels. This indicates a difference in the metabolic
activity of E. aerogenes in response to oxygen. The difference spectrum of the 2D fluorescence shows that growing E. aerogenes under high dissolved oxygen levels increases the NAD(P)H content of the cells.
Received: 2 March 1999 / Received revision: 25 May 1999 / Accepted: 28 May 1999 相似文献
20.
Fukuda K Kiyokawa Y Yanagiuchi T Wakai Y Kitamoto K Inoue Y Kimura A 《Applied microbiology and biotechnology》2000,53(5):596-600
The IAH1 gene of Saccharomyces cerevisiae encodes an esterase that preferentially acts on isoamyl acetate; however, the enzyme has not yet been completely purified
from the yeast S. cerevisiae. We constructed the IAH1 gene expression system in Escherichia coli, and purified the IAH1 gene product (Iah1p). The amount of Iah1p produced by recombinant E. coli was more than 40% of total cellular proteins. The molecular size of Iah1p was 28 kDa by SDS-polyacrylamide gel electrophoresis.
Judging from the molecular weight estimation by gel filtration of purified Iah1p, the enzyme was thought to be a homodimer.
The K
m values for isoamyl acetate and isobutyl acetate were 40.3 mM and 15.3 mM, respectively. The enzyme activity was inhibited
by Hg2+, p-chloromercuribenzoate, and diisopropylfluorophosphate.
Received: 23 May 1999 / Received revision: 27 October 1999 / Accepted: 5 November 1999 相似文献