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1.
Effect of Mineral Phosphate Solubilization on Biological Nitrogen Fixation by Diazotrophic Cyanobacteria 总被引：4，自引：0，他引：4
The ability of two diazotrophic cyanobacteria Westiellopsis prolifica and Anabaena variabilis were examined to solubilize extracellular insoluble tricalcium phosphate (TCP) and Mussorie rock phosphate (MRP). The two
strains exhibited a differential response to insoluble forms of phosphorus used. W. prolifica showed better growth in presence of MRP while A. variabilis proliferated better in presence of TCP. Biological nitrogen fixation measured in terms of acetylene reduction (AR) activity
showed significant variation among the concentrations of TCP or MRP and time of incubation. W. prolifica and A. variabilis showed maximum AR activity on 14 and 21 days of incubation respectively. In general AR activity in presence of MRP was always
less than that in presence of TCP at all concentrations. Among the two cyanobacteria A. variabilis was best in terms of P-solubilization and nitrogen fixation and TCP (20 mg P l−1) was the best source of insoluble P rather than MRP or K2HPO4. 相似文献
2.
Enterobacter asburiae PSI3 is known to efficiently solubilize rock phosphate by secretion of approximately 50 mM gluconic acid in Tris-buffered medium in the presence of 75 mM glucose and in a mixture of seven aldosugars each at 15 mM concentration, mimicking alkaline vertisol soils. Efficacy of this bacterium in the rhizosphere requires P release in the presence of low amount of sugars. To achieve this, E. asburiae PSI3 has been manipulated to express gluconate dehydrogenase (gad) operon of Pseudomonas putida KT 2440 to produce 2-ketogluconic acid. E. asburiae PSI3 harboring gad operon had 438 U of GAD activity, secreted 11.63 mM 2-ketogluconic and 21.65 mM gluconic acids in Tris-rock phosphate-buffered medium containing 45 mM glucose. E. asburiae PSI3 gad transformant solubilized 0.84 mM P from rock phosphate in TRP-buffered liquid medium. In the presence of a mixture of seven sugars each at 12 mM, the transformant brought about a drop in pH to 4.1 and released 0.53 mM P. 相似文献
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5.
Vascular wilt of carnation caused by Fusarium oxysporum f. sp. dianthi (Prill. & Delacr.) W. C. Synder & H.N. Hans inflicts substantial yield and quality loss to the crop. Mycolytic enzymes such
as chitinases are antifungal and contribute significantly to the antagonistic activity of fluorescent pseudomonads belonging
to plant-growth-promoting rhizobacteria. Fluorescent pseudomonads antagonistic to the vascular wilt pathogen were studied
for their ability to grow and produce chitinases on different substrates. Bacterial cells grown on chitin-containing media
showed enhanced growth and enzyme production with increased anti-fungal activity against the pathogen. Furthermore, the cell-free
bacterial culture filtrate from chitin-containing media also significantly inhibited the mycelial growth. Both the strains
and their cell-free culture filtrate from chitin-amended media showed the formation of lytic zones on chitin agar, indicating
chitinolytic ability. Extracellular proteins of highly antagonistic bacterial strain were isolated from cell-free extracts
of media amended with chitin and fungal cell wall. These cell-free conditioned media contained one to seven polypeptides.
Western blot analysis revealed two isoforms of chitinase with molecular masses of 43 and 18.5 kDa. Further plate assay for
mycelial growth inhibition showed the 43-kDa protein to be antifungal. The foregoing studies clearly established the significance
of chitinases in the antagonism of fluorescent pseudomonads, showing avenues for possible exploitation in carnation wilt management. 相似文献
6.
A novel phosphate solubilizing bacterium (PSB) was isolated from the rhizosphere of sugarcane and is capable of utilizing
sucrose and rock phosphate as the sole carbon and phosphate source, respectively. This PSB exhibited mineral phosphate solubilizing
(MPS) phenotype on sugars such as sucrose and fructose, which are not substrates for enzyme glucose dehydrogenase (GDH), along
with GDH substrates, viz., glucose, xylose, and maltose, as carbon sources. PCR amplification of the rRNA gene and sequence
analysis identified this bacterium as Citrobacter sp. DHRSS. On sucrose and fructose Citrobacter sp. DHRSS liberated 170 and 100 μM free phosphate from rock phosphate and secreted 49 mM (2.94 g/L) and 35 mM (2.1 g/L) acetic
acid, respectively. Growth of Citrobacter sp. DHRSS on sucrose is mediated by an intracellular inducible neutral invertase. Interestingly, in the presence of GDH substrates
like glucose and maltose, Citrobacter sp. DHRSS produced approximately 20 mM (4.36 g/L) gluconic acid and phosphate released was 520 and 570 μM, respectively.
Citrobacter sp. DHRSS GDH activity was found when grown on GDH and non-GDH substrates, indicating that it is constitutive and could act
on a wide range of aldose sugars. This study demonstrates the role of different organic acids in mineral phosphate solubilization
by rhizobacteria depending on the nature of the available carbon source. 相似文献
7.
Oxalate secretion was achieved in Pseudomonas fluorescens ATCC 13525 by incorporation of genes encoding Aspergillus niger oxaloacetate acetyl hydrolase (oah), Fomitopsis plaustris oxalate transporter (FpOAR) and Vitreoscilla hemoglobin (vgb) in various combinations. Pf (pKCN2) transformant containing oah alone accumulated 19 mM oxalic acid intracellularly but secreted 1.2 mM. However, in the presence of an artificial oxalate operon containing oah and FpOAR genes in plasmid pKCN4, Pf (pKCN4) secreted 13.6 mM oxalate in the medium while 3.6 mM remained inside. This transformant solubilized 509 μM of phosphorus from rock phosphate in alfisol which is 4.5 fold higher than the Pf (pKCN2) transformant. Genomic integrants of P. fluorescens (Pf int1 and Pf int2) containing artificial oxalate operon (plac-FpOAR-oah) and artificial oxalate gene cluster (plac-FpOAR-oah, vgb, egfp) secreted 4.8 mM and 5.4 mM oxalic acid, released 329 μM and 351 μM P, respectively, in alfisol. The integrants showed enhanced root colonization, improved growth and increased P content of Vigna radiata plants. This study demonstrates oxalic acid secretion in P. fluorescens by incorporation of an artificial operon constituted of genes for oxalate synthesis and transport, which imparts mineral phosphate solubilizing ability to the organism leading to enhanced growth and P content of V. radiata in alfisol soil. 相似文献
8.
《Cell communication & adhesion》2013,20(4-6):447-452
Cell-to-cell exchanges of signaling molecules are thought to be involved in the control of cell proliferation. Connexins, which are encoded by a family of genes expressed in a cell type-specific manner, are considered as tumor suppressors. Thyroid epithelial cells co-express connexin 32 (Cx32) and connexin 43 (Cx43) that form distinct and delocalized gap junctions in vivo. The communication-deficient rat thyroid-derived cell lines, FRTL-5 and FRT, stably transfected with the Cx32 cDNA, have a reduced proliferation rate related to a prolonged G1 cell cycle phase. To determine whether Cx32-gap junctions exert the same regulatory role in vivo, we have undertaken a program of production of transgenic mice over-expressing Cx32 specifically in thyrocytes. To this purpose, we designed a vector in which the Cx32 cDNA was fused to the gene encoding the enhanced green fluorescent protein (EGFP) and placed under the control of a strong and thyroid-specific promoter, the thyroglobulin gene promoter (pTg). In stably transfected FRTL-5 cells, the Cx32/EGFP chimeric protein forms functional gap junction channels and induces the same proliferation slowdown as native Cx32. The pTg-Cx32/EGFP construct should thus allow us to obtain the thyroid-targeted over-expression of Cx32 in the mouse to investigate the involvement of Cx32-gap junctions in thyroid growth, functional activity and propensity to form tumors. 相似文献
9.
Douglas L. Rank Mahdi A. Saeed Peter M. Muriana 《Applied and environmental microbiology》2009,75(20):6622-6625
The gene for the Salmonella enterica serovar Enteritidis fimbrial protein SefA was cloned into an Escherichia coli surface expression vector and confirmed by Western blot assay. E. coli clones expressing SefA attached to avian ovary granulosa cells and HEp-2 cells, providing evidence for the involvement of SefA in the ability of Salmonella to attach to eukaryotic cells.During the 1980s to 1990s, the worldwide increase in human Salmonella enterica serovar Enteritidis infections was associated with the consumption of contaminated eggs and egg products (13, 26, 28). In the United States, grade A shell eggs were identified as a major source contributing to Salmonella infections (19, 26, 29), and the percentage of S. Enteritidis among all Salmonella isolated from outbreaks increased from 5% to 26% from 1976 to 1996 (4). Although outbreak-associated cases due to S. Enteritidis decreased from 974 during 1998 to 2000 to 692 cases in 2004 to 2006, the 28 outbreaks in 2006 still remained above the Healthy People 2010 target of 22 (6). Despite efforts directed at reducing egg-related outbreaks, S. Enteritidis infections are still among those with the highest incidence of the seven most-reported serotypes of Salmonella (5).The large proportion of S. Enteritidis serotypes involved in food-borne outbreaks is partly attributed to the adherence elicited by surface fimbriae. Fimbriae are nonflagellar filamentous surface appendages which consist of helically arranged repeating subunit proteins called fimbrins (24). Four serologically distinct fimbriae of S. Enteritidis have been characterized according to their size (kDa) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels: SEF21, SEF18, SEF17, and SEF14 (9-11, 21). Fimbriae can mediate the aggregation of bacteria and their attachment to inert surfaces (2) and to the surfaces of eukaryotic cells, especially to carbohydrate receptors (8, 11, 36).SEF14 fimbriae are detected in all S. Enteritidis strains and are not widely distributed among the Enterobacteriaceae (10). These fimbriae consist of a repeating major subunit protein of 14.3 kDa (SefA) encoded by the gene sefA (9, 33). The results of studies by Peralta et al. (25) and Thiagarajan et al. (31) indicate that SEF14 fimbriae may have a role in pathogenesis by mediating attachment to eukaryotic cells. We focused on SEF14 fimbriae because of their limited distribution and their role as a main immunological target in the serological response to infection by S. Enteritidis in chickens (12). The objectives of this study were to clone and investigate the functional properties of the SEF14 fimbrin, SefA, as part of a fusion protein in Escherichia coli and to determine whether it could mediate adherence to tissue culture cells in vitro.Bacterial strains, tissue culture cells, and plasmids used in this study are described in Table Table1.1. Bacterial cultures were grown in LB medium (Fisher Scientific, Raleigh, NC) supplemented with 0.2% glucose and shaken at 220 revolutions min−1 or in colonization factor broth (30) at 37°C. Chloramphenicol (Cm; 10 μg ml−1) and ampicillin (Amp; 50 μg ml−1) were added as needed (Sigma-Aldrich, St. Louis, MO). Avian ovary granulosa cells were grown in 5% CO2 atmosphere at 37°C in M199 medium supplemented with 26 mM NaHCO3, 0.1% bovine serum albumin, 100 U ml−1 penicillin G, and 100 μg ml−1 streptomycin sulfate (Gibco-BRL, Gaithersburg, MD). HEp-2 cells were obtained from ATCC (Rockville, MD) and grown in 5% CO2 atmosphere at 37°C in minimum essential medium (Sigma-Aldrich), pH 7.2, supplemented with 26 mM NaHCO3, 7% fetal bovine serum, 100 U ml−1 penicillin G, and 100 μg ml−1 streptomycin sulfate (Gibco-BRL and Sigma-Aldrich).
Open in a separate windowPrimers were designed to amplify the known sefA sequence (35) corresponding to the mature protein and included restriction sites to facilitate directional cloning of the amplified target to replace the β-lactamase gene in pTX101 (27). E. coli JM109 host cells were then transformed by electroporation (Gene Pulser, Bio-Rad Laboratories, Hercules, CA). In prior studies, derivatives of pTX101 have been used successfully to express several proteins on the outer surface of E. coli cells (16, 17). The Lpp portion of pTX101 serves to localize the fusion protein to the outer membrane, while the OmpA portion traverses the outer membrane and directs the product of the cloned gene (i.e., β-lactamase or SefA) to the surface.Membrane fractions were isolated as previously described (7) with the following modifications. Cell suspensions were sonicated with an XL series sonicator (Heat Systems, Farmingdale, NY) at 100 W and then added to ice-cold Tris-Cl, and the remaining bacteria were removed by centrifugation. The total membrane was sedimented by centrifugation (45,000 × g at 4°C) for 1 h and then suspended in Tris-Cl, and the outer membrane was isolated by adding 0.5% (wt/vol) N-lauryl sarcosine (Sigma) and shaking at 200 rpm for 30 min at 22°C to dissolve the inner membrane.Crude SefA was obtained from S. Enteritidis CDC9 as described previously by Feutrier et al. (14). Purified SefA was obtained by the method of Chart (7) with the following modifications. Briefly, crude SefA was run on an SDS-PAGE gel and a portion corresponding to SefA was extracted from gel slices with Z-spin microcentrifuge columns (Pall/Gelman Sciences, Ann Arbor, MI). The purified SefA was vacuum dried and suspended in phosphate-buffered saline buffer.SDS-PAGE was performed according to the method of Laemmli (18), and proteins were visualized with Coomassie blue. An identical gel was prepared for Western blots, and proteins were transferred onto BioTrace polyvinylidene difluoride (Pall/Gelman Sciences). Western blotting was done according to the membrane manufacturer''s instructions (1). SefA monoclonal mouse antibodies 69/25 supplied by C. J. Thorns (Central Veterinary Laboratories, Weybridge, Surrey; 32) were used as the primary antibody; ImmunoPure goat anti-mouse immunoglobulin G(H+L) biotin-conjugated antibodies (Pierce, Rockford, IL) were used as the secondary antibody; and AVIDX-AP, assay buffer (0.1 M diethanolamine, 1.0 mM MgCl2, pH 10.0), I-Block, and CSPD (Applied Biosystems, Bedford, MA) were used in the chemiluminescent detection of the secondary antibodies using X-ray film. SDS-PAGE of total membrane fractions of E. coli JM109(pDUG3A) demonstrated a protein of the expected size for the Lpp-OmpA-SefA fusion protein (∼31 kDa); however, similarly sized proteins were also observed in the control strains [JM109 and JM109(pTX101)] (Fig. (Fig.1A).1A). Western blot analysis confirmed the presence of SefA in the 31-kDa band in the recombinant strain [JM109(pDUG3A)] but not in membrane protein fractions from either the host strain alone (JM109) or the host strain harboring the pTX101 vector (Fig. (Fig.1B).1B). When outer membrane fractions were selectively isolated from the inner membrane, the presence of the 31-kDa SefA fusion protein was more readily detected over the background of proteins of similar size (Fig. (Fig.1C).1C). The data provide further evidence for the localization of the SefA fusion protein in the outer membrane of E. coli JM109(pDUG3A).Open in a separate windowFIG. 1.SDS-PAGE and Western blot of SefA samples using SefA monoclonal antibodies. (A) SDS-PAGE of total membrane fractions collected from cells grown at 37°C. (B) Western blot of SDS-PAGE gel shown in panel A using monoclonal mouse antibodies 69/25 as an immunoprobe for SefA. (C) SDS-PAGE of outer membrane fractions collected from cells grown at 25°C. Lanes: 1, molecular mass standards (99.4, 66.2, 45, 31, 21.5, and 14.4 kDa); 2, crude SefA; 3, purified SefA; 4, E. coli JM109; 5, E. coli JM109(pTX101); 6, E. coli JM109(pDUG3A). Arrows indicate Lpp-OmpA-SefA fusion protein at ∼31 kDa.Attachment assays on avian ovary granulosa and HEp-2 cells were done according to the method of Thiagarajan et al. (30), with some modifications. Briefly, granulosa cells were seeded and grown as a monolayer on sterile coverslips and then washed three times with M199 medium (Gibco), and 1 × 107 CFU of bacterial cells (grown with and without 1% d-mannose) was added to the coverslips. The coverslips were then incubated in a 5% CO2 atmosphere at 37°C for 3 h, after which the cells were washed five times with M199 medium, fixed with methanol, stained with 10% Giemsa stain (Sigma), and examined by light microscopy. Attachment assays with HEp-2 cells were done as described above except that minimum essential medium (Sigma) was used as the wash solution.Peralta et al. (25) showed that in vitro attachment of S. Enteritidis to murine intestinal epithelial cells was reduced by SefA antibodies, suggesting a role for SefA in attachment. Thiagarajan et al. (30) demonstrated attachment of S. Enteritidis to avian ovary granulosa cells that form one of the layers surrounding the yolk in a preovulatory follicle. They suggest that this attachment may be a mechanism precipitating S. Enteritidis infection of hens'' ovaries that may subsequently lead to transovarian transmission to shell eggs. In our study, we compared the attachment of S. Enteritidis CDC9, E. coli JM109(pDUG3A) (sefA clone), and JM109(pTX101) (vector) to both avian granulosa (Fig. (Fig.2)2) and HEp-2 cells (Fig. (Fig.3).3). S. Enteritidis CDC9 demonstrated a mannose-resistant pattern of attachment to both granulosa and HEp-2 cells (Fig. (Fig.2A2A and and3A)3A) while JM109(pTX101) did not attach to these cell lines (Fig. (Fig.2B2B and and3B).3B). However, JM109(pDUG3A), expressing the SefA fusion protein, demonstrated mannose-sensitive attachment to both granulosa and HEp-2 cells, indicating attachment to eukaryotic cell lines attributed to the presence of SefA (Fig. (Fig.2C2C and and3C3C).Open in a separate windowFIG. 2.Attachment of indicated bacterial cells to avian ovary granulosa cells: S. Enteritidis CDC9 (A), E. coli JM109(pTX101) (B), and E. coli JM109(pDUG3A) (C). Cells were stained with 10% Giemsa stain and photographed with a light microscope at ×400 magnification.Open in a separate windowFIG. 3.Attachment of indicated bacterial cells to HEp-2 cells: S. Enteritidis CDC9 (A), E. coli JM109(pTX101) (B), and E. coli JM109(pDUG3A) (C). Cells were stained with 10% Giemsa stain and photographed with a light microscope at ×400 magnification.Thorns (34) reported that both a wild-type S. Enteritidis strain and a sefA mutant were able to attach to HEp-2 cells, indicating that multiple determinants may mediate attachment. This is also indicated by differences in mannose sensitivities of various S. Enteritidis strains (30). The results of the Western blot and cell culture attachment assays suggest that the mannose-sensitive binding of JM109(pDUG3A) is due to the presence of SefA in the outer membrane, since JM109(pTX101) did not possess SefA or show attachment. The data also indicate that the presentation of SefA in a fimbrial structure may not be necessary for binding since nonfimbrial adhesions have been reported to mediate attachment to eukaryotic cells (22). Unfolded SefA protein in the Lpp-OmpA-SefA fusion protein may possibly allow hydrophilic or hydrophobic interactions with granulosa or HEp-2 cells, providing for mannose-sensitive adherence.The data presented herein demonstrate that surface-expressed SefA protein may provide to nonadherent bacteria the property of adherence to eukaryotic cells and constitute further evidence for the involvement of SEF14 fimbriae in binding by S. Enteritidis. Heterologously expressed recombinant fimbrial antigens have been used successfully to induce immune responses in mice and pigs (3, 20). The results of previous studies have indicated that purified SefA protein is highly immunogenic and that SefA antibodies increase the survival rate of mice after challenge with S. Enteritidis from 32% in control mice to 78% in vaccinated mice (23, 25). The data warrant further studies to demonstrate whether the attachment observed in vitro could be demonstrated in vivo for possible applications in the competitive exclusion or induction of an immune response using this vector. 相似文献
TABLE 1.
Bacterial strains, tissue culture cells, and plasmids| Bacterial strain, tissue culture cell line, or plasmid | Relevant characteristics | Source or reference |
|---|---|---|
| Strains | ||
| S. Enteritidis CDC9 | Phage type 8, SEF14+sefA+ | A. M. Saeed |
| E. coli JM109 | endA1 recA1 gyrA96 thi hsdR17 (rK− mK+) mcrB+ relA1 supE44 λ− Δ(lac-proAB) supE44 [F′ traD36 proAB lacIqZΔM15] | B. Olwin |
| Tissue culture cell lines | ||
| HEp-2 cells | Epidermoid carcinoma isolated from human larynx | ATCC CCL23 |
| Granulosa cells | Isolated from chicken ovaries | A. M. Saeed |
| Plasmids | ||
| pTX101 | 12.5 kb, Ampr CmrlacIq+lpp-ompA-bla fusion expressed through Plac or Plpp | G. Georgiou (15) |
| pDUG3A | 11.5 kb, CmrlacIq+lpp-ompA-sefA fusion expressed through Plac or Plpp | This study |
10.
Doreen Babin Cordula Vogel Sebastian Zühlke Michael Schloter Geertje Johanna Pronk Katja Heister Michael Spiteller Ingrid K?gel-Knabner Kornelia Smalla 《PloS one》2014,9(9)
The fate of polycyclic aromatic hydrocarbons (PAHs) in soil is determined by a suite of biotic and abiotic factors, and disentangling their role in the complex soil interaction network remains challenging. Here, we investigate the influence of soil composition on the microbial community structure and its response to the spiked model PAH compound phenanthrene and plant litter. We used long-term matured artificial soils differing in type of clay mineral (illite, montmorillonite) and presence of charcoal or ferrihydrite. The soils received an identical soil microbial fraction and were incubated for more than two years with two sterile manure additions. The matured artificial soils and a natural soil were subjected to the following spiking treatments: (I) phenanthrene, (II) litter, (III) litter + phenanthrene, (IV) unspiked control. Total community DNA was extracted from soil sampled on the day of spiking, 7, 21, and 63 days after spiking. Bacterial 16S rRNA gene and fungal internal transcribed spacer amplicons were quantified by qPCR and subjected to denaturing gradient gel electrophoresis (DGGE). DGGE analysis revealed that the bacterial community composition, which was strongly shaped by clay minerals after more than two years of incubation, changed in response to spiked phenanthrene and added litter. DGGE and qPCR showed that soil composition significantly influenced the microbial response to spiking. While fungal communities responded only in presence of litter to phenanthrene spiking, the response of the bacterial communities to phenanthrene was less pronounced when litter was present. Interestingly, microbial communities in all artificial soils were more strongly affected by spiking than in the natural soil, which might indicate the importance of higher microbial diversity to compensate perturbations. This study showed the influence of soil composition on the microbiota and their response to phenanthrene and litter, which may increase our understanding of complex interactions in soils for bioremediation applications. 相似文献
11.
Bcl-XL is a member of Bcl-2 family of proteins involved in the regulation of intrinsic pathway of apoptosis. Its overexpression in many human cancers makes it an important target for anti-cancer drugs. Bcl-XL interacts with the BH3 domain of several pro-apoptotic Bcl-2 partners. This helical bundle protein has a pronounced hydrophobic groove which acts as a binding region for the BH3 domains. Eight independent molecular dynamics simulations of the apo/holo forms of Bcl-XL were carried out to investigate the behavior of solvent-exposed hydrophobic groove. The simulations used either a twin-range cut-off or particle mesh Ewald (PME) scheme to treat long-range interactions. Destabilization of the BH3 domain-containing helix H2 was observed in all four twin-range cut-off simulations. Most of the other major helices remained stable. The unwinding of H2 can be related to the ability of Bcl-XL to bind diverse BH3 ligands. The loss of helical character can also be linked to the formation of homo- or hetero-dimers in Bcl-2 proteins. Several experimental studies have suggested that exposure of BH3 domain is a crucial event before they form dimers. Thus unwinding of H2 seems to be functionally very important. The four PME simulations, however, revealed a stable helix H2. It is possible that the H2 unfolding might occur in PME simulations at longer time scales. Hydrophobic residues in the hydrophobic groove are involved in stable interactions among themselves. The solvent accessible surface areas of bulky hydrophobic residues in the groove are significantly buried by the loop LB connecting the helix H2 and subsequent helix. These observations help to understand how the hydrophobic patch in Bcl-XL remains stable in the solvent-exposed state. We suggest that both the destabilization of helix H2 and the conformational heterogeneity of loop LB are important factors for binding of diverse ligands in the hydrophobic groove of Bcl-XL. 相似文献
12.
Junjie Li Feng Chen Yuanbo Feng Marlein Miranda Cona Jie Yu Alfons Verbruggen Jian Zhang Raymond Oyen Yicheng Ni 《Translational oncology》2013,6(1):42-50
OBJECTIVE: Differently located tumors of the same origin may exhibit diverse responses to the same therapeutics. To test this hypothesis, we compared the responses of rodent hepatic and subcutaneous engrafts of rhabdomyosarcoma-1 (R1) to a vascular disrupting agent Combretastatin A4 phosphate (CA4P). METHODS: Twelve WAG/Rij rats, each bearing three R1 implanted in the right and left hepatic lobes and subcutaneously in the thoracic region, received CA4P intravenously at 5 mg/kg (n = 6) or solvent (n = 6). Therapeutic responses were compared interindividually and intraindividually among tumors of different sites till 48 hours after injection using in vivo MRI, postmortem digital microangiography, and histopathology. RESULTS: MRI revealed that the subcutaneous tumors (STs) significantly increased in volume than hepatic tumors (HTs) 48 hours after CA4P (P < .05). Relative to vehicle controls and treated group at baseline, necrosis ratio, apparent diffusion coefficient, and enhancement ratio changed slightly with the STs but significantly with HTs (P < .05) after CA4P treatment. Vessel density derived from microangiography was significantly lower in STs compared to HTs without CA4P treatment. CA4P treatment resulted in decreased vessel density in HTs, while it did not affect vessel density in STs. MRI and microangiography outcomes were supported by histopathologic findings. CONCLUSIONS: MRI and microangiography allowed quantitative comparison of therapeutic responses to CA4P in rats with multifocal tumors. The discovered diverse effects of the same drug on tumors of the same origin but different locations emphasize the presence of cancer heterogeneity and the importance of individualization of drug delivery. 相似文献
13.
Ed Etxeberria Pedro Gonzalez Edurne Baroja-Fernandez Javier Pozueta Romero 《Plant signaling & behavior》2006,1(4):196-200
Fluid phase endocytic uptake of external solutes in plant cells was further substantiated using artificial polystyrene nano-spheres (40 nm) and CdSe/ZnS quantum dots (20 nm). Both types of artificial nano-particles were taken up by sycamore-cultured cells. However, whereas polystyrene nano-spheres were delivered to the central vacuole, CdSe/ZnS nano-dots were sequestered into cytoplasmic vesicular structures. Using dextran-Texas Red (m.w. 3,000; d-TR) as additional marker, confocal micrographs confirmed the distinct topographic distribution of CdSe/ZnS quantum dots within the cell. Initially, d-TR and CdSe/ZnS quantum dots colocalized within cytoplasmic vesicles. After 18 h incubation, d-TR was distinctly localized in the vacuole whereas CdSe/ZnS quantum dots remained sequestered in cytoplasmic membranous compartments. The data provide a first evidence for the rapid distribution of solutes taken up by endocytosis to distinct intracellular compartments.Key Words: apoplast, assimilate partitioning, endocytosis, protoplasts, sucrose transport, sucrose uptake, vacuole 相似文献
14.
The Chlorocatechol-Catabolic Transposon Tn5707 of Alcaligenes eutrophus NH9, Carrying a Gene Cluster Highly Homologous to That in the 1,2,4-Trichlorobenzene-Degrading Bacterium Pseudomonas sp. Strain P51, Confers the Ability To Grow on 3-Chlorobenzoate 
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下载免费PDF全文 Alcaligenes eutrophus (Ralstonia eutropha) NH9, isolated in Japan, utilizes 3-chlorobenzoate as its sole source of carbon and energy. Sequencing of the relevant region of plasmid pENH91 from strain NH9 revealed that the genes for the catabolic enzymes were homologous to the genes of the modified ortho-cleavage pathway. The genes from strain NH9 (cbnR-ABCD) showed the highest homology (89 to 100% identity at the nucleotide level) to the tcbR-CDEF genes on plasmid pP51 of the 1,2,4-trichlorobenzene-degrading bacterium Pseudomonas sp. strain P51, which was isolated in The Netherlands. The structure of the operon, including the lengths of open reading frames and intervening sequences, was completely conserved between the cbn and tcb genes. Most nucleotide substitutions were localized within and proximal to the cbnB (tcbD) gene. The difference in the chloroaromatics that the two strains could use as growth substrates seemed to be due to differences in enzymes that convert substrates to chlorocatechols. The restriction map of plasmid pENH91 was clearly different from that of pP51 except in the regions that contained the cbnR-ABCD and tcbR-CDEF genes, respectively, suggesting that the chlorocatechol gene clusters might have been transferred as units. Two homologous sequences, present as direct repeats in both flanking regions of the cbnR-ABCD genes on pENH91, were found to be identical insertion sequences (ISs), designated IS1600, which formed a composite transposon designated Tn5707. Although the tcbR-CDEF genes were not associated with similar ISs, a DNA fragment homologous to IS1600 was cloned from the chromosome of strain P51. The sequence of the fragment suggested that it might be a remnant of an IS. The two sequences, together with IS1326 and nmoT, formed a distinct cluster on a phylogenetic tree of the IS21 family. The diversity of the sources of these IS or IS-like elements suggests the prevalence of ISs of this type. 相似文献
15.
Functional ability is often impaired for people with rheumatoid arthritis (RA), rendering these patients highly sedentary. Additionally, patients with RA often take medication known to negatively affect bone mass. Thus improving functional ability and bone health in this group of patients is important. The aim of this study was to investigate the effects of whole body vibration (WBV) therapy in patients with stable, established RA. Thirty one females with RA were randomly assigned to a control group (CON, n = 15) who continued with their normal activities or a WBV group (n = 16) who underwent a three month WBV therapy intervention, consisting of 15 minutes of intermittent vibration, performed twice per week. Patients were assessed at baseline, three months, and three months post intervention for functional ability using the modified Health Assessment Questionnaire; for RA disease activity using the Clinical Disease Activity Index, for quality of life using self-report fatigue and pain scores; for physical activity profiles using accelerometry, and for BMD and body composition using DXA. Patients in both groups were matched for all variables at baseline. After the intervention period, functional ability was significantly improved in the WBV group (1.22(0.19) to 0.92(0.19), p = 0.02). Hip BMD was significantly reduced in the CON group (0.97(0.05) to 0.84(0.05) g.cm-2, p = 0.01), while no decreases were seen in the WBV group (1.01(0.05) to 0.94(0.05) g.cm-2, p = 0.50). Despite no change in RA disease activity in either group at either follow up, fatigue levels were improved in the WBV group (4.4(0.63) to 1.1(0.65), yet remained unchanged in the CON group at both follow ups (p = 0.01). Ten minute bouts of light to moderate physical activity were significantly reduced in the CON group after the intervention (2.8(0.61) to 1.8(0.64) bouts per day, p = 0.01), and were preserved in the WBV group (3.1(0.59) to 3.0(0.61) bouts per day, p = 0.70). Intermittent WBV shows promise for sustained improvements in functional ability, for attenuating loss of bone mass at the hip, as well as for decreasing fatigue in patients with established RA.Trial Registration: Pan African Clinical Trials Registry PACTR201405000823418 相似文献