共查询到20条相似文献,搜索用时 0 毫秒
1.
Nick P 《Protoplasma》2007,230(3-4):125-127
2.
Quantum dots as photosensitizers? 总被引:11,自引:0,他引:11
3.
Plant and Soil - Current definitions of essential or beneficial elements for plant growth rely on narrowly defined criteria that do not fully represent a new vision for plant nutrition and... 相似文献
4.
5.
Environmental scanning electron microscopy (ESEM) enables the investigation of hydrated and uncoated plant samples and the in situ observation of dynamic processes. Water vapor in the microscope chamber takes part in secondary electron detection and charge prevention. Two ESEM modes are available and offer a broad spectrum of applications. The environmental or wet mode prevents sample dehydration by the combination of sample cooling (5°C) and a vapor pressure of 4–6 Torr. In the low vacuum mode, the maximum chamber pressure is limited to 1 Torr (corresponding to about 5% relative humidity in the chamber) and allows the simultaneous use of a backscattered electron detector for imaging material contrast. A selection of characteristic plant samples and various applications are presented as a guide to ESEM for plant scientists. Leaf surfaces, trichomes, epicuticular waxes, and inorganic surface layers represent samples being comparatively resistant to dehydration, whereas callus cells and stigmatic tissue are examples for dehydration- and beam-sensitive samples. The potential of investigating dynamic processes in situ is demonstrated by studying anther opening, by tensile testing of leaves, and by performing hydration/dehydration experiments by changing the vapor pressure. Additionally, automated block-face imaging and serial sectioning using in situ ultramicrotomy is presented. The strengths and weaknesses of ESEM are discussed and it is shown that ESEM is a versatile tool in plant science. 相似文献
6.
David Perrett 《Nucleosides, nucleotides & nucleic acids》2018,37(11):588-602
AbstractThis paper is a personal review of the role developments in separation science over the last four decades have played in the diagnosis and understanding of purine and pyridine metabolism particularly in man. In 1967 the separation of nucleotides was used to demonstrate a new chromatography technique. This technique became known as HPLC and which continues to dominate the analysis of purines etc. The resolution and quantitation offered by even the earliest HPLC systems completely changed our understanding of matters such as nucleotide instability in cells and tissues, diagnosis of in born errors, etc. Capillary Electrophoresis also enabled high resolution as well as the quantitation of usual analytes such allantoin. Now LC-MS dominates the diagnostic field. This paper is based on the Anne Simmonds Lecture given by the author at PP17 in Gdansk in 2017. 相似文献
7.
《Journal of biological education》2012,46(1):62-64
The use of the word ‘fact’ in science is discussed. It is suggested that the everyday meaning of the term is assumed when it is used in science and that this can create problems. Some possible ways of overcoming these difficulties are indicated. 相似文献
8.
9.
John Sheail 《Biodiversity and Conservation》2000,9(8):1099-1113
There is no lack of pretext for reviewing historically how ecologists have striven to gain the respect of scholars in their own and other fields, and to demonstrate the wider public-utility of their science. If self-serving, in terms of securing the scope and resources required to advance their studies in ecology, such activities have also been encouraged, and indeed commissioned, in the belief that a greater awareness and understanding of the natural world is essential for human wellbeing. Illustrative material is drawn from the British experience. 相似文献
10.
Flexistyly is a recently documented stylar polymorphism involving both spatial and temporal segregation of sex roles within hermaphroditic flowers. Using the experimental manipulation of stigma movement in self-compatible Alpinia mutica, we tested the hypothesis that selection for reducing interference between male and female function drives the evolution and/or maintenance of stigma movement. In experimental arrays, anaflexistylous (protogynous) flowers served as pollen donors competing for mating opportunities on cataflexistylous (protandrous) flowers. The pollen donors were either manipulated so their stigmas could not move or were left intact, and their success was determined using allozymes to assess the paternity of recipient seeds. We found that manipulated flowers sired a significantly smaller proportion of seeds, showing that stigma movement in unmanipulated plants increased male fitness. This result was strongest under conditions in which pollen competition was expected to be highest, specifically when pollinators visited multiple donor plants before visiting recipient flowers. 相似文献
11.
Karolina Zaleska 《Reports of Practical Oncology and Radiotherapy》2015,20(2):79-86
Objective
The aim of this study was to review the current knowledge about involvement of microRNAs in breast cancer, and their potential in the clinic, published in scientific journals searched in Pubmed/Medline database until March 2014.Results
MicroRNAs (miRNAs) are a family of 21–25 nucleotide small RNAs molecules. Currently, it is well known that miRNA plays a key role in all cellular processes of the organism including tumour initiation and progression. Many studies have shown that circulating miRNAs are attractive, easily detectable tumour biomarkers. Breast cancer is one of the most common cancers in the world. It is clinically established that different subtypes may respond differently to therapies, give metastases and present drug resistance. MicroRNAs have a potential as diagnostic, prognostic and therapeutic tools in breast cancer.Conclusion
Molecular knowledge is crucial for choosing the most effective therapy for individual patients. MicroRNAs holds a great potential in anticancer therapy. 相似文献12.
Kalpesh D. Mahajan Qirui Fan Jenny Dorcéna Gang Ruan Dr. Jessica O. Winter 《Biotechnology journal》2013,8(12):1424-1434
Quantum dots (QDs) have great promise in biological imaging, and as this promise is realized, there has been increasing interest in combining the benefits of QDs with those of other materials to yield composites with multifunctional properties. One of the most common materials combined with QDs is magnetic materials, either as ions (e.g. gadolinium) or as nanoparticles (e.g. superparamagnetic iron oxide nanoparticles, SPIONs). The fluorescent property of the QDs permits visualization, whereas the magnetic property of the composite enables imaging, magnetic separation, and may even have therapeutic benefit. In this review, the synthesis of fluorescent–magnetic nanoparticles, including magnetic QDs is explored; and the applications of these materials in imaging, separations, and theranostics are discussed. As the properties of these materials continue to improve, QDs have the potential to greatly impact biological imaging, diagnostics, and treatment. 相似文献
13.
14.
Arasimowicz-Jelonek M Floryszak-Wieczorek J Kosmala A 《Plant biology (Stuttgart, Germany)》2011,13(5):747-756
In the present work, we tested known nitric oxide (NO) modulators generating the NO+ (sodium nitroprusside, SNP) and NO˙ forms (S-nitroso-N-acetyl-D-penicillamine, SNAP and nitrosoglutathione, GSNO). This allowed us to compare downstream NO-related physiological effects on proteins found in leaves of pelargonium (Pelargonium peltatum L.). Protein modification via NO donors generally affects plant metabolism in a distinct manner, manifested by a lower thiobarbituric acid reactive substance (TBARS) content and lipoxygenase (LOX) activity in response to SNAP and GSNO. This is in contrast to the response observed for SNP treatment. Most changes in enzyme activity (GR, glutathione reductase; GST, glutathione-S-transferase; GPX, glutathione peroxidase) are most spectacular and repeatable during the first 8 h of incubation, which is explained by the half-life of the applied donors. In particular, a close dependence was found between the time-course of NO emission from the applied donors and the temporary inhibition of antioxidant enzymes, such as catalase (CAT) and ascorbate peroxidase (APX). The observed changes were accompanied by time-dependent alterations in protein accumulation as analysed by two-dimensional gel electrophoresis (2-DE) in pelargonium leaves treated with NO donors (SNP, SNAP and GSNO). Using proteomics, different proteins were found to be down- and up-regulated. However, no new protein spots characteristic of all three donors were found. These results indicate that the form of NO emitted from the donor structure plays a key role in switching on appropriate metabolic modifications. It has been noted that several NO-affected metabolomic changes induced by the used donors were not comparable, which confirms the need to maintain caution when interpreting results obtained using the pharmacological approach with different NO modulator compounds. 相似文献
15.
16.
Xia Cai Qian Wang Yu Fang Die Yao Yunda Zhan Baoju An Bing Yan Jun Cai 《Microbial biotechnology》2021,14(6):2538-2551
With the rapid development of synthetic biology in recent years, particular attention has been paid to RNA devices, especially riboswitches, because of their significant and diverse regulatory roles in prokaryotic and eukaryotic cells. Due to the limited performance and context-dependence of riboswitches, only a few of them (such as theophylline, tetracycline and ciprofloxacin riboswitches) have been utilized as regulatory tools in biotechnology. In the present study, we demonstrated that a ribosome-dependent ribo-regulator, LRR, discovered in our previous work, exhibits an attractive regulatory performance. Specifically, it offers a 60-fold change in expression in the presence of retapamulin and a low level of leaky expression of about 1–2% without antibiotics. Moreover, LRR can be combined with different promoters and performs well in Bacillus thuringiensis, B. cereus, B. amyloliquefaciens, and B. subtilis. Additionally, LRR also functions in the Gram-negative bacterium Escherichia coli. Furthermore, we demonstrate its ability to control melanin metabolism in B. thuringiensis BMB171. Our results show that LRR can be applied to regulate gene expression, construct genetic circuits and tune metabolic pathways, and has great potential for many applications in synthetic biology. 相似文献
17.
S. Lüthje P. Van Gestelen M. C. Córdoba-Pedregosa J. A. González-Reyes H. Asard J. M. Villalba M. Böttger 《Protoplasma》1998,205(1-4):43-51
Summary The occurrence of a vitamin-K-like substance (naphthoquinone group) and flavins (flavin mononucleotide and flavin adenine dinucleotide) is demonstrated in plasma membranes isolated from maize (Zea mays L.) roots, on the basis of high-pressure liquid chromotography and spectral analysis. At least three NAD(P)H dehydrogenases could be purified to homogeneity from this plant material. Two of these proteins (25 and 30 kDa) reduce hexacyanoferrate III and quinones, while the third (41 kDa) reduces oxalacetic acid but not hexacyanoferrate III in the presence of NADH. Low-temperature spectra demonstrate the occurrence of a b-type cytochrome in plasma membranes isolated from maize roots. The latter compound could be reduced by ascorbic acid (E0 > +80 mV) and shows an -band maximum at 559 nm (at –196 °C). NADH-dependent cytochromeb reduction could be observed only in the presence of detergent and increased after preincubation with vitamin K3 (menadione). On the basis of the presented data a possible function of naphthoquinones in plasma membrane electron transfer is discussed.Abbreviations Brij 58
polyoxyethylene 20 cetyl ether
- Coenzyme
Q10 ubiquinone-50
- duroquinone
tetramethyl-p-benzoquinone
- E0
standard redox potential
- Na2EDTA
ethylenediaminetetraacetic acid disodium salt
- HEPES
N-[2-hydroxyethyl]piperazine-N[2-ethane-sulfonic acid]
- juglone
5-hydroxy-1,4-naphthoquinone
- PMSF
phenylmethylsulfonyl fluoride
- vitamin
K1 2-methyl-3-phyty 1-1,4-naphthoquinone
- vitamin K3
2-methyl-1,4-naphthoquinone 相似文献
18.
19.
20.