共查询到20条相似文献,搜索用时 15 毫秒
1.
Xiao-Hua Cai Christopher Brown Jagat Adhiya Samuel J Traina Richard T Sayre 《International journal of phytoremediation》1999,1(1):53-65
We have compared the growth rates and cadmium binding capacity of wild-type and transgenic Chlamydomonas reinhardtii cells expressing a foreign class-II metallothionein. We observed that cells expressing metallothionein grew to significantly higher cell densities than wild-type cells in the presence of a toxic cadmium concentration (40 μM). When grown at a low (5 μM) cadmium concentration, cells expressing metallothionein bound twofold more cadmium (0.43 μg Cd)mg Ch1) than wild-type. At cadmium concentrations (40 μM), which induce phytochelatin synthesis in wild-type cells the cadmium binding capacity of both wild-type (79.6 μg Cd)mg Ch1) and transformed cells (86.4 μg Cd)mg Ch1) was similar; however, the transformed cells grew to higher densities than the wild type. These results suggest that under conditions that apparently induce phytochelatin expression, the presence of metallothionein in the cytoplasm reduces heavy metal toxicity. Furthermore, because cells expressing metallothionein grow to higher densities than wild-type cells at a toxic cadmium concentration (40 μM), the transgenic cells sequester more total cadmium (9% of total Cd) from the medium than the wild type (5.5% of total Cd). These results indicate that the trace-metal binding properties of Chlamydomonas can be enhanced through the expression of trace-metal-specific binding proteins. 相似文献
2.
Heavy metal-mediated activation of the rat Cu/Zn superoxide dismutase gene via a metal-responsive element 总被引:5,自引:0,他引:5
The Cu/Zn superoxide dismutase (SOD1) catalyzes the dismutation of superoxide radicals produced in the course of biological
oxidations. When placed under the control of the rat SOD1 gene promoter and transfected into human HepG2 hepatoma cells, the activity of a chloramphenicol acetyltransferase reporter
gene was found to increase three- to four-fold in the presence of heavy metals (cadmium, zinc and copper). Functional analysis
of mutant derivatives of the SOD1 gene promoter and the use of a heterologous promoter system confirmed that the induction of the SOD1 gene by metal ions requires a metal-responsive element (MRE) located between positions −273 and −267 (GCGCGCA). It was also
shown by gel mobility shift assays that an MRE binding protein is induced by the exposure of the human liver cell line HepG2
to heavy metals. These results suggest that the MRE participates in the induction of the SOD1 gene by heavy metals.
Received: 5 February 1999 / Accepted: 21 May 1999 相似文献
3.
Somatic hybridization between the zinc accumulator Thlaspi caerulescens and Brassica napus 总被引:6,自引:0,他引:6
E. P. Brewer J. A. Saunders J. Scott Angle R. L. Chaney M. S. McIntosh 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,99(5):761-771
Somatic hybrids between the zinc hyperaccumulator Thlaspi caerulescens and Brassica napus were produced by electrofusion of protoplasts isolated from each species. Optimization of electrofusion parameters yielded
interspecies heteroplasmic fusion rates of up to 13%. Hybrids were selected by screening the growing calli for Zn tolerance.
In addition, a second novel selection technique was developed based on the observation that a high proportion of hybrid microcalli
grown in liquid media did not adhere to the wall of the culture vessel, while microcalli derived from parental cells did.
Seventeen from a total of 64 regenerated plants were conclusively verified as hybrids by AFLP DNA analysis. The hybrid plants
were grown in soil for up to 4 months, and at least five flowered. Several of these hybrids survived when grown on high-zinc
media.These hybridsaccumulated levels of zinc and cadmium that would have been toxic for B. napus. The data indicate that transfer of the trait for metal hyperaccumulation in plants is possible through somatic hybridization.
Received: 1 December 1998 / Accepted: 30 January 1999 相似文献
4.
5.
Effect of flow rate on heavy metal accumulation by rotating biological contactor (RBC) biofilms 总被引:1,自引:0,他引:1
Immobilized biofilms are effective in heavy metal removal. The current studies investigated the use of rotating biological
contactor (RBC) biofilms in treatment of a wastewater containing cadmium, copper and zinc, each at a concentration of 100 mg
L−1. In particular, the influence of hydraulic retention time (HRT) on metal accumulation was studied. Longer HRTs (>12 h) were
associated with greater metal removal than short HRTs, particularly with regard to cadmium and zinc. The system was also shown
to operate successfully over an extended period of time, at an HRT of 24 h, with removal efficiencies of approximately 34%,
85% and 57% for Cd2+, Cu2+ and Zn2+ respectively after 5–8 weeks contact. Journal of Industrial Microbiology & Biotechnology (2000) 24, 244–250.
Received 28 July 1999/ Accepted in revised form 21 December 1999 相似文献
6.
B. Dugdale D. K. Becker P. R. Beetham R. M. Harding J. L. Dale 《Plant cell reports》2000,19(8):810-814
The intergenic regions of banana bunchy top virus (BBTV) DNA-1 to -5 were fused to the green fluorescent protein (GFP) and
uidA reporter genes and assessed for promoter activity in transgenic banana (Musa spp. cv. Bluggoe). Promoter activity associated with the BBTV-derived promoters was transgene dependent with greatest activity
observed using the GFP reporter. The BBTV promoters (BT1 to BT5) directed expression primarily in vascular-associated cells,
although levels of activity varied between individual promoters. Promoters BT4 and BT5 directed the highest levels of GFP
expression, while activity from BT1, BT2 and BT3 promoters was considerably weaker. Intron-mediated enhancement, using the
maize polyubiquitin 1 (ubi1) intron, generated a significant increase in GUS expression directed by the BBTV promoters in transgenic plants.
Received: 17 May 1999 / Revision received: 3 November 1999 / Accepted: 4 November 1999 相似文献
7.
Transgenic oat plants via visual selection of cells expressing green fluorescent protein 总被引:11,自引:0,他引:11
H. F. Kaeppler G. K. Menon R. W. Skadsen A. M. Nuutila A. R. Carlson 《Plant cell reports》2000,19(7):661-666
New selectable markers and selection systems are needed to increase the efficiency and flexibility of plant transformation.
The objective of this research was to determine if the green fluorescent protein (gfp) gene could be utilized as a visual selectable marker for transformation of oat (Avena sativa L.). A modified gfp gene was delivered into oat cells by microprojectile bombardment. Cell clusters expressing gfp were visually identified using fluorescence microscopy and physically isolated at each subculture. Eleven independent transgenic
cell lines were obtained, and fertile plants regenerated from all lines. Transgene integration and expression were confirmed
in transgenic plants and progeny. Transgene expression segregated in a 3 : 1 ratio in progeny of the majority of the transgenic
lines.
Received: 11 May 1999 / Revision received: 31 August 1999 / Accepted: 2 September 1999 相似文献
8.
Prosopis juliflora is a tree species that grows well in heavy metal laden industrial sites and accumulates heavy metals. To understand the possible
contribution of metallothioneins (MTs) in heavy metal accumulation in P. juliflora, we isolated and compared the metal binding ability of three different types of MTs (PjMT1-3). Glutathione S-transferase fusions of PjMTs (GSTMT1-3) were purified from Escherichia coli cells grown in the presence of 0.3 mM cadmium, copper or zinc. Analysis of metal bound fusion proteins using atomic absorption
spectrometry showed that PjMT1 bound higher levels of all three heavy metals as compared to PjMT2 and PjMT3. A comparative
analysis of the genomic regions (including promoter for all three PjMTs) is also presented. All three PjMTs are induced by H2O2 and ABA applications. PjMT1 and PjMT2 are induced by copper and zinc respectively while PjMT3 is induced by copper, zinc and cadmium. Variation in induction of PjMTs in response to metal exposure and their differential binding to metals suggests that each MT has a specific role in P. juliflora. Of the three MTs analyzed, PjMT1 shows maximum heavy metal sequestration and is thus a potential candidate for use in heavy
metal phytoremediation. 相似文献
9.
Aniefon Ibuot Rachel E. Webster Lorraine E. Williams Jon K. Pittman 《Biotechnology and bioengineering》2020,117(10):2996-3005
The use of microalgal biomass for metal pollutant bioremediation might be improved by genetic engineering to modify the selectivity or capacity of metal biosorption. A plant cadmium (Cd) and zinc (Zn) transporter (AtHMA4) was used as a transgene to increase the ability of Chlamydomonas reinhardtii to tolerate 0.2 mM Cd and 0.3 mM Zn exposure. The transgenic cells showed increased accumulation and internalization of both metals compared to wild-type. AtHMA4 was expressed either as the full-length (FL) protein or just the C-terminal (CT) tail, which is known to have metal-binding sites. Similar Cd and Zn tolerance and accumulation was observed with expression of either the FL protein or CT domain, suggesting that enhanced metal tolerance was mainly due to increased metal binding rather than metal transport. The effectiveness of the transgenic cells was further examined by immobilization in calcium alginate to generate microalgal beads that could be added to a metal contaminated solution. Immobilization maintained metal tolerance, while AtHMA4-expressing cells in alginate showed a concentration-dependent increase in metal biosorption that was significantly greater than alginate beads composed of wild-type cells. This demonstrates that expressing AtHMA4 FL or CT has great potential as a strategy for bioremediation using microalgal biomass. 相似文献
10.
Transformation and regeneration of garlic (Allium sativum L.) by Agrobacterium-mediated gene transfer 总被引:5,自引:0,他引:5
By using highly regenerative calluses, we developed a stable transformation system in garlic (Allium sativum L.). The temperature and number of days of co-cultivation with Agrobacterium tumefaciens was shown to be an important factor in transient expression of the uid A gene. After a culture period of 5 months in selection medium containing hygromycin, 20 shoots were induced from ca. 1000
calluses, among which 15 plants expressed β-glucuronidase activity upon staining with X-Gluc. Shoots developed into transgenic garlic after 1 month. Integration of the uid A gene was confirmed by Southern blot analysis for genomic DNA of transgenic garlic plants.
Received: 25 October 1999 / Revision received: 16 February 2000 / Accepted: 22 February 2000 相似文献
11.
Agrobacterium-mediated engineering for sheath blight resistance of indica rice cultivars from different ecosystems 总被引:3,自引:0,他引:3
K. Datta Z. Koukolíková-Nicola N. Baisakh N. Oliva S.K. Datta 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,100(6):832-839
A concise T-DNA element was engineered containing the rice class-I chitinase gene expressed under the control of CaMV35S and the hygromycin phosphotransferase gene (hph) as a selectable marker. The binary plasmid vector pNO1 with the T-DNA element containing these genes of interest was mobilized
to Agrobacterium
tumefaciens strain LBA4404 to act as an efficient donor of T-DNA in the transformation of three different indica rice cultivars from
different ecosystems. Many morphologically normal, fertile transgenic plants from these rice cultivars were generated after
Agrobacterium-mediated transformation using 3-week-old scutella calli as initial explants. Stable integration, inheritance and expression
of the chimeric chitinase gene were demonstrated by Southern blot and Western blot analysis of the transformants. Bioassay data showed that transgenic
plants can restrict the growth of the sheath blight pathogen Rhizoctonia solani. Bioassay results were correlated with the molecular analysis. Although we obtained similar results upon DNA-mediated transformation,
this report shows the potential of the cost-effective, simple Agrobacterium system for genetic manipulation of rice cultivars with a pathogenesis-related (PR) gene.
Received: 26 July 1999 / Accepted: 27 August 1999 相似文献
12.
Zinc concentrations in pelagic surface waters are within the range that limits growth in marine phytoplankton cultures. However, the influence of zinc on marine primary production and phytoplankton communities is not straightforward due to largely uncharacterized abilities for some phytoplankton to access zinc species that may not be universally bioavailable and substitute zinc with cobalt or cadmium. We used a quantitative proteomic approach to investigate these strategies and other responses to zinc limitation in the coccolithophore Emiliania huxleyi, a dominant species in low zinc waters. Zinc limitation resulted in the upregulation of metal transport proteins (ZIP, TroA-like) and COG0523 metallochaperones. Some proteins were uniquely sensitive to growth under replete zinc, substitution of zinc with cobalt, or enhancement of growth with cadmium, and may be useful as biomarkers of zinc stress or substitution in situ. Several proteins specifically upregulated under cobalt-supported or cadmium-enhanced growth appear to reflect stress responses, despite titration of these metals to optimal nutritive levels. Relief from zinc limitation by zinc or cadmium resulted in increased expression of a δ-carbonic anhydrase. Our inability to detect metal binding enzymes that are specifically induced under cobalt- or cadmium-supported growth suggests cambialism is important for zinc substitution in E. huxleyi. 相似文献
13.
The binding of gold(I) to metallothionein, MT, has been unambiguously established by the reaction of Na2AuTM with purified horse kidney MT. Zinc was displaced more readily than cadmium although the latter could be displaced using large Au/Cd ratios. The metal exchange reactions were complete within 2 hr of mixing. Further evidence that such reactions might be physiologically significant were obtained by studying in vitro metal displacements in the liver cytosol of in vivo metal treated rats: When Na2AuTM was added to the cytosol of rats administered CdCl2 in vivo, zinc, copper and cadmium were displaced in 2/1/1 ratios from the metallothionein fraction. The zinc and cadmium displacement provide direct evidence that the gold was binding to MT. Addition of Cd+2 to liver cytosol of gold-treated rats resulted in displacement of copper and zinc, but not gold, from the MT fractions. When liver MT is prepared from rats exposed to Au or Cd, the Cd/protein ratio increased during the preparation, but the Au/protein ratio decreased. The Mt-bound metals account for 95% of the cytosolic Cd but only 15%–30% of the cytosolic gold in these studies. Thus, the nonspecific binding of gold to MT in vivo should be considered as one aspect in its equilibration among protein binding sites, which include, inter alia, metallothionein. Gold was found to coelute with zinc and cadmium in the MT fraction of rat kidney cytosol, when both Cd and Na2AuTM were administered to the rats. The possible significance of gold binding to MT in the treatment of rheumatoid arthritis-chrysotherapy-is briefly discussed. 相似文献
14.
High-frequency stable transformation of cotton (Gossypium hirsutum L.) by particle bombardment of embryogenic cell suspension cultures 总被引:6,自引:0,他引:6
K. Rajasekaran R. L. Hudspeth J. W. Cary D. M. Anderson T. E. Cleveland 《Plant cell reports》2000,19(6):539-545
Stable transformation of cotton (Gossypium hirsutum L.) at a high frequency has been obtained by particle bombardment of embryogenic cell suspension cultures. Transient and
stable expression of the β-glucuronidase (GUS) gene was monitored in cell suspension cultures. Transient expression, measured 48 h after bombardment,
was abundant, and stable expression was observed in over 4% of the transiently expressing cells. The high efficiency of stable
expression is due to the multiple bombardment of rapidly dividing cell suspension cultures and the selection for transformed
cells by gradually increasing the concentrations of the antibiotic Geneticin (G418). Southern analysis indicated a minimum
transgene copy number of one to four in randomly selected plants. Fertile plants were obtained from transformed cell cultures
less than 3 months old. However, transgenic and control plants from cell cultures older than 6 months produced plants with
abnormal morphology and a high degree of sterility.
Received: 20 January 1999 / Revision received: 1 October 1999 / Accepted: 11 October 1999 相似文献
15.
Terashima M Murai Y Kawamura M Nakanishi S Stoltz T Chen L Drohan W Rodriguez RL Katoh S 《Applied microbiology and biotechnology》1999,52(4):516-523
Recombinant human α1-antitrypsin (rAAT) was expressed and secreted from transgenic rice cell suspension cultures in its biologically active form.
This was accomplished by transforming rice callus tissues with an expression vector, p3D-AAT, containing the cDNA for mature
human AAT protein. Regulated expression and secretion of rAAT from this vector was achieved using the promoter, signal peptide,
and terminator from a rice α-amylase gene Amy3D. The Amy3D gene of rice is tightly controlled by simple sugars such as sucrose. It was possible, therefore, to induce the expression
of the rAAT by removing sucrose from the cultured media or by allowing the rice suspension cells to deplete sucrose catabolically.
Although transgenic rice cell produced a heterogeneous population of the rAAT molecules, they had the same N-terminal amino
acids as those found in serum-derived (native) AAT from humans. This result indicates that the rice signal peptidase recognizes
and cleaves the novel sequence between the Amy3D signal peptide and the first amino acid of the mature human AAT. The highest molecular weight band seen on Western blots
(AAT top band) was found to have the correct C-terminal amino acid sequence and normal elastase binding activity. Staining
with biotin-concanavalin A and avidin horseradish peroxidase confirmed the glycosylation of the rAAT, albeit to a lesser extent
than that observed with native AAT. The rAAT, purified by immunoaffinity chromatography, had the same association rate constant
for porcine pancreatic elastase as the native AAT. Thermostability studies revealed that the rAAT and native AAT decayed at
the same rate, suggesting that the rAAT is correctly folded. The productivity of rice suspension cells expressing rAAT was
4.6–5.7 mg/g dry cell. Taken together, these results support the use of rice cell culture as a promising new expression system
for production of biologically active recombinant proteins.
Received: 18 January 1999 / Received revision: 26 April 1999 / Accepted: 1 May 1999 相似文献
16.
D Di Simine C Finoli A Vecchio V Andreoni 《Journal of industrial microbiology & biotechnology》1998,20(2):116-120
This paper explores the use of an experimental system based on polyacrylamide-entrapped cells of Brevibacterium sp strain PBZ for the removal of metal ions from solutions. Experiments were performed in columns filled with the immobilised
cells and challenged with influents containing 20 mg L−1 of lead and 10 mg L−1 of cadmium. The cells were able to accumulate lead (about 40 mg g−1 dry biomass) and, to a lesser extent, cadmium (about 13 mg g−1 dry biomass) from solutions. In the presence of 0.4 g L−1 of glucose, the cells removed up to 53% of lead. Lead competed with cadmium for attachment to the binding sites when a solution
containing both the metals was applied. Lead removal occurred by a combination of fast physico-chemical adsorption and prolonged
low rate accumulation mediated by cell metabolism. The biosorptive capacity of the cells was sensitive to pH. Desorption of
the metal with EDTA restored the binding capability of the cells.
Received 07 July 1997/ Accepted in revised form 26 November 1997 相似文献
17.
18.
19.
Agrobacterium tumefaciens-mediated transformation and transgenic-plant regeneration of onion (Allium cepa L.) 总被引:3,自引:3,他引:0
An Agrobacterium tumefaciens-mediated transformation method has been developed for onions (Allium cepa L.) using immature embryos as the explant source. Transgenic plants were recovered from the open-pollinated onion cultivar
Canterbury Longkeeper at a maximum transformation frequency from immature embryos of 2.7%. The method takes between 3–5 months
from explant to primary regenerant entering the glasshouse. Multiple-shoot formation from primary transgenic material made
possible the clonal multiplication of transformants. The binary vector used carried the nptII antibiotic resistance gene and the m-gfp5-ER reporter gene. Transgenic cultures were initially screened for their ability to fluoresce and to grow in the presence of
geneticin (5–25 mg/l). The transgenic nature of individual plants was confirmed by Southern blot analysis.
Received: 12 October 1998 / Revision received: 17 May 1999 Accepted: 14 June 1999 相似文献
20.
Endogeneous levels of zinc and copper were found to be 1.2±0.1×10−2 and 0.3±0.1×10−2 μg/A260 unit, respectively, in polysomal fractions from control animals; cadmium, however, was undetectable. In experimental
animals (injected with cadmium) zinc, copper, and cadmium were found in polysomal fractions isolated by two different methods.
One hour after a cadmium injection there was a rise in both the zinc and copper content of the polysomal fractions, which
then declined steadily to below control levels by 16 h. Neither zinc nor cadmium were dialyzable from these fractions by a
TRIS buffer; however, addition of 0.01M EDTA to the buffer resulted in removal of 75% of the zinc and all of the detectable cadmium.
The addition of cadmium (CdCl2) to control supernatants (adjusted to the cadmium concentration present in supernatants 6 h after in vivo exposure) resulted
in metal binding to polysomal fractions in levels comparable to those observed after in vivo exposures to the metal. When
cadmium was added in the form of cadmium thionein, a smaller fraction of the metal was isolated with the polysomal fraction.
Cadmium bound to polysomal fractions in vivo (24 h after exposure) was sensitive to release by protease digestion, but insensitive
to release by ribonuclease digestion. 相似文献