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1.
Oligonucleotide directed mutagenesis of the human beta-globin gene: a general method for producing specific point mutations in cloned DNA. 总被引:33,自引:11,他引:33
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A nonadecanucleotide has been used both as a site specific mutagen to introduce a T leads to A transversion mutation in the human beta-globin gene cloned in pBR322 as well as a probe to screen transformed colonies for the desired mutant. The specificity of the oligonucleotide as a mutagen and as a hybridization probe provide a general method for producing site specific mutations in DNA cloned in plasmid vectors such as pBR322. 相似文献
2.
Tissue microarrays have become an essential tool in translational pathology. They are used to confirm results from other experimental
platforms, such as expression microarrays, as well as a primary tool to explore the expression profile of proteins by immunohistochemical
analysis. Tissue microarrays are routinely used molecular epidemiology, drug development and determining the diagnostic, prognostic
and predictive value of new biomarkers. By applying traditional protein based assays, as well as novel assays to the platform,
tissue microarrays have gained a new utility as a proteomic tool for both basic science as well as clinical investigation.
This article will explore the new approaches that are being applied to tissue microarrays to, characterize the human proteome,
and new technologies that allow tissue microarrays to function as a protein array.
The U.S. Government's right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged 相似文献
3.
D C Taylor 《BMJ (Clinical research ed.)》1982,284(6321):1027-1028
The parents of handicapped children have to adjust to a wide variety of emotional and psychological problems when first confronted with the failure of their reproductive expectations. Counselling is a formal procedure or transaction in which both counsellor and parents aim to find a mutually acceptable plan of adjustment. Parents may need support to cope with their own personal inadequacies as well as with their own personal inadequacies as well as with the needs of the child. Counselling should be a continuous process, in which the parents can learn to accept the child as a different rather than a lesser person. 相似文献
4.
5.
Taft RA 《Theriogenology》2008,69(1):10-16
The mouse is the most widely used model of preimplantation embryo development, but is it a good model? Its small size, prolificacy and ease of handling make the mouse a relatively low cost, readily available and attractive alternative when embryos from other species are difficult or expensive to obtain. However, the real power of the mouse as a model lies in mouse genetics. The development of inbred mouse strains facilitated gene discovery as well as our understanding of gene function and regulation while the development of tools to introduce precise genetic modifications uniquely positioned the mouse as a powerful model system for uncovering gene function. However, all models have limitations; the small size of the mouse limits tissue availability and manipulations that can be performed and differences in physiology among species may make it inappropriate to extrapolate from the mouse to other species. Thus, rather than extrapolating directly from the mouse to other species, it may be more useful to use the mouse as a model system for developing and refining hypotheses to be tested directly in species of interest. In this brief review, the value of the preimplantation mouse embryo as a model is considered, both as a model for other species and as a model for the mouse, as understanding the virtues and limitations of the mouse as a model system is essential to its appropriate use. 相似文献
6.
O'Malley MA Müller-Wille S 《Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences》2010,41(3):169-171
Although the cell is commonly addressed as the unit of life, historians and philosophers have devoted relatively little attention to this concept in comparison to other fundamental concepts of biology such as the gene or species. As a partial remedy to this neglect, we introduce the cell as a major point of connection between various disciplinary approaches, epistemic strategies, technological vectors and overarching biological processes such as metabolism, growth, reproduction and evolution. We suggest that the role of the cell as a nexus forms the basis for a new philosophical and historical appreciation of cell biology. This perspective focuses less on the cell as a well-defined, stable object and places more emphasis on its role as a mediator of fundamental biological processes. 相似文献
7.
8.
N Nanninga 《Microbiology and molecular biology reviews》2001,65(2):319-33 ; third page, table of contents
Cytokinesis requires duplication of cellular structures followed by bipolarization of the predivisional cell. As a common principle, this applies to prokaryotes as well as eukaryotes. With respect to eukaryotes, the discussion has focused mainly on Saccharomyces cerevisiae and on Schizosaccharomyces pombe. Escherichia coli and to a lesser extent Bacillus subtilis have been used as prokaryotic examples. To establish a bipolar cell, duplication of a eukaryotic origin of DNA replication as well as its genome is not sufficient. Duplication of the microtubule-organizing center is required as a prelude to mitosis, and it is here that the dynamic cytoskeleton with all its associated proteins comes to the fore. In prokaryotes, a cytoskeleton that pervades the cytoplasm appears to be absent. DNA replication and the concomitant DNA segregation seem to occur without help from extensive cytosolic supramacromolecular assemblies but with help from the elongating cellular envelope. Prokaryotic cytokinesis proceeds through a contracting ring, which has a roughly 100-fold-smaller circumference than its eukaryotic counterpart. Although the ring contains proteins that can be considered as predecessors of actin, tubulin, and microtubule-associated proteins, its macromolecular composition is essentially different. 相似文献
9.
Fundamentals of flow cytometry 总被引:4,自引:0,他引:4
Flow cytomelers arc instruments that arc used primarily to measure the physical and biochemical characteristics of biological
particles. This technology is used to perform measurements on whole cells as well as prepared cellular constituents, such
as nuclei and organelles. Flow cytomcters are investigative tools for a broad range of scientific disciplines because they
make measurements on thousands of individual cells/ particles in a matter of seconds. This is a unique advantage relative
to other detection instruments that provide bulk particle measurements. Flow cytomety is a complex and highly technical field;
therefore, a basic understanding of the technology is essential for all users. The purpose of this article is to provide fundamental
information about the instrumentation used for flow cytometry as well as the methods used to analyze and interpret data. This
information will provide a foundation to use flow cytometry effectively as a research tool. 相似文献
10.
《Bioorganic & medicinal chemistry》2020,28(10):115463
1-Phenyl-3-methyl-5-pyrazolone is a reagent, known as PMP, used to derivatize monosaccharides for the study of polysaccharides composition and structure, and for the dosage of carbohydrates in complex media. The same molecule is also known as edaravone, a drug approved for the treatment of stroke and amyotrophic lateral sclerosis. It is also a reactive molecule susceptible to form stable adducts with aromatic aldehydes, such as formylpterin and vanillin. In addition, the molecule serves as a scaffold to design of edaravone analogs and drug conjugates, with various pharmacological properties (antioxidant, anticancer, antiviral). We have analyzed the multiple usages of PMP/edaravone to highlight the reactivity of the molecule and its wide range of applications. This phenyl-pyrazolone compound, considered by many as a biochemical reagent and by other as a clinically useful drug, has not yet revealed the full extent of its capacities and benefits. 相似文献
11.
Simmons MP Clevinger CC Savolainen V Archer RH Mathews S Doyle JJ 《American journal of botany》2001,88(2):313-325
Phylogenetic relationships within Celastraceae were inferred using a simultaneous analysis of 61 morphological characters and 1123 base pairs of phytochrome B exon 1 from the nuclear genome. No gaps were inferred, and the gene tree topology suggests that the primers were specific to a single locus that did not duplicate among the lineages sampled. This region of phytochrome B was most useful for examining relationships among closely related genera. Fifty-one species from 38 genera of Celastraceae were sampled. The Celastraceae sensu lato (including Hippocrateaceae) were resolved as a monophyletic group. Loesener's subfamilies and tribes of Celastraceae were not supported. The Hippocrateaceae were resolved as a monophyletic group nested within a paraphyletic Celastraceae sensu stricto. Goupia was resolved as more closely related to Euphorbiaceae, Corynocarpaceae, and Linaceae than to Celastraceae. Plagiopteron (Flacourtiaceae) was resolved as the sister group of Hippocrateoideae. Brexia (Brexiaceae) was resolved as closely related to Elaeodendron and Pleurostylia. Canotia was resolved as the sister group of Acanthothamnus within Celastraceae. Perrottetia and Mortonia were resolved as the sister group of the rest of the Celastraceae. Siphonodon was resolved as a derived member of Celastraceae. Maytenus was resolved as three disparate groups, suggesting that this large genus needs to be recircumscribed. 相似文献
12.
Bacteria able to use at least one of 13 ionic alkylphosphonates of O-alkyl or O,O-dialkyl alkylphosphonates as phosphorus sources were isolated from sewage and soil. Four of these isolates used 2-aminoethylphosphonic acid (AEP) as a sole carbon, nitrogen, and phosphorus source. None of the other phosphonates served as a carbon source for the organisms. One isolate, identified as Pseudomonas putida, grew with AEP as its sole carbon, nitrogen, and phosphorus source and released nearly all of the organic phosphorus as orthophosphate and 72% of the AEP nitrogen as ammonium. This is the first demonstration of utilization of a phosphonoalkyl moiety as a sole carbon source. Cell-free extracts of P. putida contained an inducible enzyme system that required pyruvate and pyridoxal phosphate to release orthophosphate from AEP; acetaldehyde was tentatively identified as a second product. Phosphite inhibited the enzyme system. 相似文献
13.
This paper provides an introduction to the theory of steady-state fluctuation relations for molecular dynamics systems, that led to a general theory of response. The main ingredient of this theory is a new dynamical condition now known as t-mixing. We use such a condition to identify necessary and sufficient conditions for the relaxation to a steady state (whether equilibrium or not) of an ensemble of identical systems, as well as of a single system. This allows us to address the problem of the irreversibility of time reversal invariant (conservative as well as dissipative) particle systems. 相似文献
14.
A solvent-tolerant, slightly thermophilic bacterium was isolated at 45 degrees C in the presence of toluene vapor provided as the sole carbon source. Strain T27 was identified as Deinococcus geothermalis T27. It could tolerate high concentrations of solvent provided as a nonaqueous layer (5% and 20%, v/v) to a cell suspension and had a remarkable ability to tolerate a broad range of solvents having log P(ow) values ranging from 5.6 of n-decane to as low as 0.7 of ethyl acetate. It was also able to utilize some of the solvents tested as a growth substrate at 45 degrees C. The addition of Ca(2+) ion, glucose and fructose partially promoted solvent tolerance. Cells exposed to ethyl acetate appeared to have a smaller size; however, the cell structure was not altered and was apparently well defined even after solvent shock. The tolerance of D. geothermalis T27 in the presence of high levels of toxic solvent stress at a comparatively high temperature indicated its potential use in biotechnological applications as well as bioremediation of xenobiotics. 相似文献
15.
In this study, whole cells and a crude enzyme of Candida peltata were applied to an electrochemical bioreactor, in order to induce an increment of the reduction of xylose to xylitol. Neutral red was utilized as an electron mediator in the whole cell reactor, and a graphite-Mn(IV) electrode was used as a catalyst in the enzyme reactor in order to induce the electrochemical reduction of NAD(+) to NADH. The efficiency with which xylose was converted to xylitol in the electrochemical bioreactor was five times higher than that in the conventional bioreactor, when whole cells were employed as a biocatalyst. Meanwhile, the xylose to xylitol reduction efficiency in the enzyme reactor using the graphite-Mn (IV) electrode and NAD(+) was twice as high as that observed in the conventional bioreactor which utilized NADH as a reducing power. In order to use the graphite-Mn(IV) electrode as a catalyst for the reduction of NAD(+) to NADH, a bioelectrocatalyst was engineered, namely, oxidoreductase (e.g. xylose reductase). NAD(+) can function in this biotransformation procedure without any electron mediator or a second oxidoreductase for NAD(+)/NADH recycling. 相似文献
16.
The utility of plants as biofactories has progressed in recent years. Some recombinant plant-derived pharmaceutical products
have already reached the marketplace. However, with the exception of drugs and vaccines, a strong effort has not yet been
made to bring recombinant products to market, as cost-effectiveness is critically important for commercialization. Sweet-tasting
proteins and taste-modifying proteins have a great deal of potential in industry as substitutes for sugars and as artificial
sweeteners. The taste-modifying protein, miraculin, functions to change the perception of a sour taste to a sweet one. This
taste-modifying function can potentially be used not only as a low-calorie sweetener but also as a new seasoning that could
be the basis of a new dietary lifestyle. However, miraculin is far from inexpensive, and its potential as a marketable product
has not yet been fully developed. For the last several years, biotechnological production of this taste-modifying protein
has progressed extensively. In this review, the characteristics of miraculin and recent advances in its production using transgenic
plants are summarized, focusing on such topics as the suitability of plant species as expression hosts, the cultivation method
for transgenic plants, the method of purifying miraculin and future advances required to achieve industrial use. 相似文献
17.
Recent data suggest that we age, in part, because our self-renewing stem cells grow old as a result of heritable intrinsic events, such as DNA damage, as well as extrinsic forces, such as changes in their supporting niches. Mechanisms that suppress the development of cancer, such as senescence and apoptosis, which rely on telomere shortening and the activities of p53 and p16(INK4a), may also induce an unwanted consequence: a decline in the replicative function of certain stem-cell types with advancing age. This decreased regenerative capacity appears to contribute to some aspects of mammalian ageing, with new findings pointing to a 'stem-cell hypothesis' for human age-associated conditions such as frailty, atherosclerosis and type 2 diabetes. 相似文献
18.
Recent developments in the apoptosis field have uncovered a family of cysteine proteases, the Caspases, that act as signalling
components as well as effectors of the cell death machinery. Caspases are constitutively present as inactive precursors within
most cells and undergo proteolytic processing in response to diverse death-inducing stimuli to initiate the death programme.
Active caspases can process other caspases of the same type as well as process caspases further downstream in the pathway
that ultimately leads to collapse of the cell. This cellular collapse is thought to occur as a consequence of caspase-mediated
cleavage of a diverse array of cellular substrates. Regulation of entry into the death programme is controlled at a number
of levels by members of the Bcl-2 family, as well as by other cell death regulatory proteins. Recent data has shed light upon
the mechanism of action of these regulatory molecules and suggests that the point of caspase activation is a major checkpoint
in the cell death programme. Because many transformed cell populations possess derangements in cell death-regulatory genes,
such as bcl-2, such cells frequently exhibit elevated resistance to cytotoxic chemotherapy. Thus, a deeper understanding of
how apoptosis is normally regulated has therapeutic implications for disease states where the normal controls on the cell
death machinery have been subverted.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
19.
In this essay we argue for the possibility to describe the co-presence of species in a community as a consortium built by acoustic codes, using mainly the examples of bird choruses. In this particular case, the consortium is maintained via the sound-tope that different bird species create by singing in a chorus. More generally, the formation of acoustic codes as well as cohesive communicative systems (the consortia) can be seen as a result of plastic adaptational behaviour of the specimen who can solve and avoid conflicts both with conspecifics and with other species in the vicinity. Thus, sign-relations appear to resolve potential conflicts, and as a foundation for symbiotic aggregations. The spatio-temporal configuration of consortia—their chronotope—includes several eco-fields as respective to different functions of the participating organisms. Biological study is combined with a semiotic approach that, as we suggest, should be more often used together to effectively describe ecological processes. 相似文献
20.
Silvia Barbi Massimo Messori Tiziano Manfredini Martina Pini Monia Montorsi 《Biopolymers》2019,110(5):e23250
In this study proteins extracted from prepupae of Hermetia illucens, also known as black soldier fly, are investigated as promising base for a new type of bioplastics for agricultural purposes. Design of experiments techniques are employed to perform a rational study on the effects of different combination of glycerol as plasticizer, citric acid as cross-linking agent and distilled water as solvent on the capability of proteins to form a free-standing film through casting technique, keeping as fixed the quantity of proteins. Glycerol shows interesting properties as plasticizer contributing to the formation of homogenous and free-standing film. Moreover, mechanical and thermal characterizations are performed to estimate the effect of increasing amounts of proteins on the final properties and thickness of the specimens. Proteins derived from H. illucens can be successfully employed as base for bioplastics to be employed for agricultural purposes. 相似文献