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1.
Two auxin-inducible glutathione S-transferase (GST, EC 2.5.1.18) isozymes from tobacco (Nicotiana tabacum, White Burley) were partially characterized. GST1-1 and GST2-1 are members of a recently identified new type of plant GST isozymes that we will here refer to as type III. Both enzymes were active, with 1-chloro-2,4-dinitrobenzene as a substrate, when expressed in bacteria as fusion proteins. The apparent Km for 1-chloro-2,4-dinitrobenzene was found to be 0.85 [plus or minus] 0.25 mM for GST1-1 and 0.20 [plus or minus] 0.15 mM for GST2-1. The apparent Km for glutathione was similar for both enzymes, 0.40 [plus or minus] 0.15 mM. The in vitro activity of both enzymes could be inhibited by the synthetic auxin 2,4-dichlorophenoxyacetic acid, with an apparent Ki of 80 [plus or minus] 40 [mu]M for GST1-1 and 200 [plus or minus] 100 [mu]M for GST2-1. The GST1-1 was also inhibited by structurally related substances, such as 2,4-dichlorobenzoic acid, with a roughly similar Ki. The nonchlorinated structures benzoic acid and phenoxyacetic acid did not inhibit. p-Chloroisobutyric acid, or clofibric acid, an auxin-transport inhibitor, was found to be an active inhibitor as well. The strongest inhibitor identified, however, was a phenylacetic acid derivative, ethacrynic acid, which showed an apparent Ki of 5 [plus or minus] 5 [mu]M for both enzymes. This substance is a known inducer as well as a substrate of specific mammalian GSTs. The results presented here indicate that the type III plant GSTs might be involved in the metabolism or transport of chlorinated substances that are structurally related to auxins. The possibility that auxins are endogenous ligands or substrates for GSTs is discussed.  相似文献   

2.
3.
Spectral analysis and fingerprinting for biomedia characterisation   总被引:3,自引:0,他引:3  
Classical culture media, as well as domestic and/or industrial wastewater treated by biological processes, have a complex composition. The on-line and/or in situ determination of some substances is possible, but expensive, as sample collection and pre-treatment are often necessary with strict rules of sterility. More global methods can be used to detect rapidly "accidents" such as the appearance of an undesirable by-product in a fermentation broth or of a toxic substance in wastewater. These methods combine a "hard" part, for sensing, and a "soft" part, for data treatment. Among potential "hard" candidates, spectroscopy can be the basis for non-invasive and non-destructive measuring systems. Some of them have been already tested in situ: ultra-violet-visible, infra-red (mid or near), fluorescence (mono-dimensional, two-dimensional or synchronous), dielectric, while others, more sophisticated, such as mass spectrometry, coupled or not to pyrolysis, nuclear magnetic resonance and Raman spectroscopy, have been proposed. All these methods provide spectra, i.e. large sets of data, from which meaningful information should be rapidly extracted, either for analysis or fingerprinting. The recourse to data-mining techniques (the "soft" part) such as principal components analysis, projection on latent structures or artificial neural networks, is a necessary step for that task. A review of techniques, mostly based on spectroscopy, with examples taken in the bioengineering field in general is proposed.  相似文献   

4.
The purpose of the study was to examine the validity of alpha1-microglobulin (alpha1-MG) in comparison with popularly used beta2-microglobulin (beta2-MG). A database was revisited to select ca. 7,500 spot urine samples (of adequate urine density) from non-pregnant, non-lactating and never-smoking adult women. The validity of the MGs was examined in terms of stability of the MG-uria prevalence in urine samples of various creatinine (CR or cr) concentration or specific gravity (SG or sg). Comparisons were made for MGs as observed (e.g., alpha1-MGob), as corrected for CR (e.g., alpha1-MGcr) and as corrected for SG of 1.016 (e.g., alpha1-MGsg). A cut-off value of 5.7 mg/g cr (or mg/l) for alpha1-MG was deduced from a cut-off value of 400 microg/g cr (or mcirog/l) for beta2-MG, because the correlation between alpha1-MGcr and beta2-MGcr was statistically significant. The prevalence of a 1-MGsg-uria was essentially unchanged (i.e., from a low of 13.6% to a high of 17.0%, or 1.2 times) except for in very dense or very thin urine samples, in contrast, beta2-MGcr-uria showed a substantial increase (from 0.0% to 2.8% with an infinite rate) as a reverse function of a decrease in CR in urine. The prevalence of uncorrected markers, i.e., alpha1-MGob-uria and beta2-MGob-uria, showed even greater CR- or SG-dependent changes. Thus, it appeared prudent to consider a alpha-MGsg rather than beta2-MGcr as a marker of tubular dysfunction among a general population with various urine density.  相似文献   

5.
Interferon induction and utilization   总被引:5,自引:0,他引:5  
The interferon mechanism offers the hope for moderate to high level prophylactic immunity of broad antiviral spectrum but of relatively short duration. Economic and biological considerations offer little hope for utilization of exogenous interferon as a prophylactic or therapeutic substance, unless but a small part of the total molecule be found to carry the activity. The real promise for interferon application is in the administration of suitable inducers so as to cause the body to produce and distribute its own interferon. Certain ribonucleic acids (RNA's) offer hope for high level potency as inducers without adverse effect. The condition for interferon induction by ribonucleic acids appears to be double- or multistrandedness and freedom from inhibitors. These can be of biologic or synthetic origin. The mechanism of action of interferon is not fully understood but appears to fit into the Jacob-Monod model involving two phases: first, a derepression by the inducer to cause the cell to form interferon and second, a derepression by interferon to cause recipient cells to form the active substance which acts by preventing translation from viral messenger RNA. Double or multistranded RNA of viral or other origin appears to be unique to the cell and serves as the alert to it to produce interferon in phase 1. Greatest need for interferon is clearly for those diseases in which there is a multiplicity of immunologic types in excess of the numbers which could be put into a vaccine as, e.g., the common cold and enteric viruses. There might be some overall therapeutic benefit also if inducer were given early enough in infection. Special value for interferon induction might derive by administration in early life before the development of immunologic maturity, as a means for preventing infection with oncogenic or other viruses. Additionally, suitable inducers might be capable of interrupting the reinfection cycle in virus-dependent malignancies. The favorable outlook for interferon utilization must always be tempered with the realization that under certain as yet undiscovered situations, adverse rather than beneficial effects might result from indution of interferon. It is not impossible that in certain special circumstances, as in ordinary immunologic responses, it might be more beneficial to negate rather than to promote the effect.  相似文献   

6.
Mechanically-induced stress (MIS) occurs naturally in plants as the aerial parts are moved, usually by wind, but also by such agents as rain and animals. It can be induced indoors by various actions such as rubbing or bending the stem or shaking or brushing the entire shoot. The most noticeable effect of MIS is a reduction in stem, leaf or petiole length invariably resulting in plants which are smaller and more compact than unstressed controls. However, the response of other variables can often differ between species and there may be either increases or decreases in stem or petiole diameter, root: shoot weight ratio, chlorophyll content or drought resistance. Why species should differ in this way, and what is the endogenous control mechanism for MIS responses, are inanswered questions. Ethylene, which increases as a result of MIS in several species may cause some MIS responses such as increased stem diameter, epinasty or a change in sex expression. However, evidence suggests that MIS retardation of extension growth may equally be due to lower or supraoptimal auxin levels or lower gibberellin levels.The uses in the field of the growth promoter gibberellin or the growth retardant chlormequat chloride (CCC) appear to be examples of respectively reversing or stimulating MIS growth response. MIS may be applied indoors if short compact plants are needed, either for aesthetic purposes as with floral crops, or if hardier and more manageable plants are needed, such as seedlings for transplanting in the field. Much more research is needed to estimate the importance of MIS in the field and to assess how such knowledge may be used to improve crop yield.  相似文献   

7.
Our experience with combined procedures in aesthetic plastic surgery   总被引:3,自引:0,他引:3  
The instep flap needs neither muscle nor a transposition base for survival or innervation. It can be transposed as an island fasciocutaneous flap either on the medial or lateral plantar neurovascular bundles or both, and it can be transferred also as a free flap from the opposite foot. Four cases demonstrating the use of the flap as an island and free flap are presented with follow-up ranging from 1 to 2 years. The absence of muscle in the flap provides greater stability of the heel reconstruction and results in a lesser secondary defect. Sensation in the flaps is diminished but adequate for long-term function, but hyperkeratotic reaction remains an unpredictable problem. The ability to transfer the flap as a free transfer widens the scope of the flap to reconstruct both heel and forefoot defects where local instep tissue or vascularity are inadequate for local reconstruction. The secondary defect, particularly when no muscle is included in the flap, has been minimal.  相似文献   

8.
The work provides a simple method, based on a direct density equilibrium measurement, for the rapid in situ estimation of total lipid, hydrocarbon or biopolymer content in a variety of prokaryotic and eukaryotic samples. The method can be readily applied to live microalgae and photosynthetic bacteria, single‐celled or colonial microorganisms, as well as cellular fractions and isolated subcellular compartments or components. In this approach, the absolute lipid, hydrocarbon, or biopolymer content of the cells can be readily calculated. This method is especially useful for tracking the oil or polymer content of strains of microalgae and other microorganisms, whose lipid, hydrocarbon or biopolymer content may change with cultivation conditions and/or time, as the case would be in microorganism lipid‐induction industrial processes. The method is also useful for the direct in situ measurement of storage polymer accumulation in live cells, such as starch in microalgae and polyhydroxybutyrate, or other polyhydroxyalkanoates, in photosynthetic and non‐photosynthetic bacteria. Biotechnol. Bioeng. 2009;102: 1406–1415. © 2008 Wiley Periodicals, Inc.  相似文献   

9.
This paper examined the association between grip type, hand use, and fingerprint patterns in a sample of captive chimpanzees. Grip type for simple reaching was assessed for the left and right hand and classified as thumb-index, middle-index, or single-digit responses. Fingerprint patterns were characterized as whorls, loops, or arches on each finger. The results indicated that chimpanzees exhibit significantly more thumb-index responses for the right compared to the left hand. In addition, thumb-index responses were more prevalent for subjects that had a whorl compared to a loop or arch on their thumb. The results suggest that fingerprint patterns are associated with individual differences in grasping type in chimpanzees as well as some variation in hand use.  相似文献   

10.
Formamide Sensitivity: A Novel Conditional Phenotype in Yeast   总被引:3,自引:1,他引:2       下载免费PDF全文
A. Aguilera 《Genetics》1994,136(1):87-91
Yeast mutants unable to grow in the presence of 3% formamide have been isolated in parallel with mutants sensitive to either 37° or 6% ethanol. The number of formamide-sensitive mutations that affect different genes that can be identified from yeast cells is at least as large as the number of thermosensitive or ethanol-sensitive mutations. These mutations are of two types: those that are sensitive to formamide, temperature and/or ethanol simultaneously; and those that are specific for formamide sensitivity and show no temperature or ethanol sensitivity phenotype. Those genes susceptible to giving rise to formamide-sensitive alleles include the structural gene for DNA ligase, CDC9, and the structural gene for arginine permease, CAN1. The results indicate that formamide sensitivity can be used as a novel conditional phenotype for mutations on both essential and nonessential genes. This work also confirms that ethanol-sensitivity can be used as a conditional phenotype to identify mutations in at least as many genes as those susceptible to temperature or formamide sensitive mutations.  相似文献   

11.
Several prodrug approaches were taken to mask amino groups in two potent and selective neuronal nitric oxide synthase (nNOS) inhibitors containing either a primary or secondary amino group to lower the charge and improve blood–brain barrier (BBB) penetration. The primary amine was masked as an azide and the secondary amine as an amide or carbamate. The azide was not reduced to the amine under a variety of in vitro and ex vivo conditions. Despite the decrease in charge of the amino group as an amide and as carbamates, BBB penetration did not increase. It appears that the uses of azides as prodrugs for primary amines or amides and carbamates as prodrugs for secondary amines are not universally effective for CNS applications.  相似文献   

12.
Although the chick embryo, including its extraembryonic membranes, has long been used as a model for developmental biology, its potential as a model for the repair and regeneration of adult human tissues is often overlooked. The chick offers a well-defined profile of intercellular and intracellular signaling pathways regulating the development of nearly every organ system in conjunction with great flexibility for chimeric and transgenic experiments. Depending upon the system of interest, the chick can either directly reflect the human condition, as in spinal cord repair or in chorioallantoic membrane wound healing, and therefore act as an in vivo model for repair, or mirror our aspired therapy as in limb generation or otic restoration and therefore act as our guide. With these unique opportunities, the chick embryo is certainly a model to be considered when aiming to develop a regenerative therapy for human applications.  相似文献   

13.
Immunoadsorbents with a synthetic oligosaccharide hapten representing human blood group A specific substances are prepared. The synthetic hapten, known as A-trisaccharide, which carries a space arm, is chemically attached to various solid supports, either directly through a suitable functional group at the end of the spacer arm or indirectly via a protein conjugated to the hapten. The preparation involves simple and mild procedures for the activation and/or derivatization of the supports. The latter includes naturally occurring polyhydroxy materials such as agarose, cellulose, or cellulose derivatives, and other particulate materials such as inorganic diatomites and a synthetic organic copolymer. The methods used for the coupling concern specifically the preparation of controlled-capacity and high-efficiency immunoadsorbents, with limited incorporations, which may be prepared easily and used for the selective removal, or affinity chromatographic separation, of specific antibodies from plasma environment or blood. It has been found that while hapten incorporation to the support may be varied rather easily, the physical nature of the support as well as the form of the hapten is important in determining the efficiency of an immunoadsorbent.  相似文献   

14.
An apparatus for cutting single or serial sections of calcified bone and teeth consists of a motor-driven shaft on which is mounted one saw (for single section cutting) or a gang (for serial sectioning at one cutting operation). The plastic-embedded specimen is attached to a cylindrical plastic holder which is in turn mounted on the machine and fed into the saw. Prior to cutting the specimen may be oriented in two planes, as well as rotated, with respect to the cutting edge. Single or serial sections made by means of repeated cuts with a single saw, may be 0.3 mm or more thick as determined by the setting of a micrometer screw. For serially sectioning a tooth or bone specimen at one cutting operation, the thickness of the separators between adjacent saws (0.5 mm or more) determines the section thickness. After sectioning, specimens may be ground and polished, with or without reimbedding in fresh plastic.  相似文献   

15.
The results of the search for potential helical lipid binding regions in a number of well-known food proteins is described. All selected food proteins have either well-described or strong indications of protein-lipid interaction features. The results are obtained with the aid of a number of selected bioinformatics tools. The identified potential lipid binding regions either correspond nicely with regions demonstrated experimentally or can be identified as novel lipid binding regions. The results are discussed in relation to earlier found experimental results and if relevant are discussed in mechanistic terms as well. A possible general use of the approach as used in this study is discussed as well. The in this study described approach can be used as a tool to come to a more focused approach for further research of yet unknown proteins. It is also possible to use this approach for more directed research when it comes to for example rational functional design of proteins for particular desired features like the emulsifying or foaming ability of the protein of interest.  相似文献   

16.
Peptide reagents can serve as alternatives or replacements to antibodies in sensing or diagnostic applications. The passive adsorption of peptides onto polystyrene surfaces can limit the target binding capability, especially for short, positively charged, or hydrophobic sequences. In this report, we show that fusing a peptide with a previously characterized 12-amino acid polystyrene binding sequence (PS-tag) improves overall peptide solubility and enzyme-linked immunosorbent assay (ELISA) results using the peptide as a capture agent. Specific improvements for protective antigen (PA; Bacillus anthracis) protein binding peptides selected from bacterial surface display were compared with native or biotinylated peptides. The PS-tag was added to either peptide terminus, using a (Gly)(4) spacer, and comparable binding affinities were obtained. Fusion with the PS-tag did not have any negative impact on peptide secondary structure as measured by circular dichroism. The addition of the PS-tag provides a convenient method to utilize peptide reagents from peptide display libraries as capture agents in an ELISA format without the need for a biotin tag or concerns about passive adsorption of critical residues for target capture.  相似文献   

17.
The DNA of growing cells of Escherichia coli occurs in one or a few lobular bodies known as nucleoids. Upon exposure to chloramphenicol, the nucleoids assume compact, rounded forms ("cm-nucleoids") that have been described as ring- or sphere-shaped. Multiple views of single cells or spheroplasts, however, support a different, curved toroid shape for cm-nucleoids. The multiple views were obtained either by DNA fluorescence imaging as the cells or spheroplasts reoriented in liquid medium or by optical sectioning using phase-contrast or fluorescence imaging of immobilized cells. The curved toroid shape is consistent with electron microscope images of thin sections of chloramphenicol-treated cells. The relationship of this structure to active and inactive nucleoids and to the smaller toroidal forms made by in vitro DNA condensation is discussed.  相似文献   

18.
Four different series of nucleolipids or bola-nucleolipids were synthesized or re-synthesized. Most of the compounds were studied with respect to their gelation properties toward either water or aromatic, hetero-aromatic, and aliphatic hydrocarbons. Bola-nucleolipids 6 and 7 do not gelate any solvent tested, neither as sole additive nor by adding up to 10 wt% of a 1:1 mixture. The nucleolipid 22 carrying the antiviral acyclovir as a head group proved to be a potent organogelator for aromatic hydrocarbons such as toluene, but not for hetarenes, aliphatic hydrocarbons or water. The mono-tailed nucleolipid 24 exhibits excellent organogelator properties for both aromatic and aliphatic hydrocarbons. These were studied as a function of concentration and temperature.  相似文献   

19.
Human health concerns with GM crops   总被引:2,自引:0,他引:2  
Malarkey T 《Mutation research》2003,544(2-3):217-221
Biotechnology was used in the first generation of so-called 'GM' crops to provide growers with complimentary and sometimes alternative crop management solutions to pesticides. Selected host genes or genes identified from other plants or non-plant sources are modified or transferred to a crop plant. The new or altered protein expression resulting from these modifications confer on the plant a desired physiological trait, such as resistance to particular herbicides or insect pests. Second generation modifications provide traits such as enhanced nutritional or health-promoting characteristics that are of benefit to consumers. The commonly raised concerns about possible implications for human health are: inherent toxicity of the novel gene and their products, the potential to express novel antigenic proteins or alter levels of existing protein allergens, the potential for unintended effects resulting from alterations of host metabolic pathways or over expression of inherently toxic or pharmacologically active substances and the potential for nutrient composition in the new food occur differing significantly from a conventional counterpart. Foods produced using biotechnology are subjected to far greater levels of scrutiny than foods produced by traditional plant breeding techniques. The accepted analytical, nutritional and toxicological methods employed to support this scrutiny and to assess and assure that a 'GM' food is a safe and nutritious as its 'non-GM' counterpart are discussed. The challenges associated with identifying unintended effects in whole GM foods and the promise new (proteomics/genomic) technologies offer opposite traditional toxicity testing paradigms are appraised.  相似文献   

20.
Identification of nucleotides used for RNA chain initiation or for contacting DNA binding proteins is basic to our understanding of gene regulation. Normally, a radioactive primer is used to copy RNA or DNA. The polymerase extension stops at free ends of mRNA (as in promoter mapping) or at the position of template cleavage or modification (as in footprinting). The locations of these positions are then analyzed by polyacrylamide gel electrophoresis. These analyses have been improved using fluorescently labeled primers and commonly available DNA sequencing machines. The protocol, which we call fluorescently labeled oligonucleotide extension (FLOE), eliminates the need for handling radioactivity and polyacrylamide. The DNA sequencer delivers data as a "trace" that is ready for quantification, which eliminates the need to trace gels separately. The data analysis is further improved by new software, Scanalyze, which we present here. We demonstrate that by using promoter mapping and footprinting, FLOE shortens experimental time, extends the stretch of analyzable sequence, and simplifies quantification compared to radioactive methods and is as sensitive in terms of detecting templates.  相似文献   

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