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The content of both inorganic and organic pollutants, in sediment from the Orlík reservoir (Vltava river, Czech Republic), and the main tributaries, was determined to assess the total loads of the pollutants in the upper layer of sediment (0–30 cm), and the potential bioaccessibility and bioavailability of these pollutants. Organic pollutants showed non-hazardous levels of polycyclic aromatic hydrocarbons and polychlorinated biphenyls. Elevated phosphorus content indicated the possible eutrophization potential; however, significant correlation of phosphorus with iron and aluminum suggested a high immobilization rate of this element with iron and aluminum cations. Risk elements in the sediment were separated according to their potential environmental risk: (1) cobalt, nickel, copper, lead, vanadium, and chromium showed both low levels and relatively low mobility, i.e. low environmental risk; (2) the arsenic levels were significantly elevated (exceeding the maximum allowable limits for land application of sediment) but its mobility was low; (3) cadmium and zinc exceeded the limits and showed high mobility and bioaccessibility. These two elements also showed high bioavailability for the bivalves Unio tumidus and Anodonta anatina. The results showed differences in pollutant loads in sediment along the lake, and different input of pollutants via the individual tributaries.  相似文献   

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Recurrent implantation failure (RIF) refers to cases in which women have had three failed in vitro fertilization (IVF) attempts with good quality embryos. The definition should also take advanced maternal age and embryo stage into consideration. The failure of embryo implantation can be a consequence of uterine, male, or embryo factors, or the specific type of IVF protocol. These cases should be investigated to determine the most likely etiologies of the condition, as this is a complex problem with several variables. There are multiple risk factors for recurrent implantation failure including advanced maternal age, smoking status of both parents, elevated body mass index, and stress levels. Immunological factors such as cytokine levels and presence of specific autoantibodies should be examined, as well as any infectious organisms in the uterus leading to chronic endometritis. Uterine pathologies such as polyps and myomas as well as congenital anatomical anomalies should be ruled out. Sperm analysis, pre-implantation genetic screening and endometrial receptivity should be considered and evaluated, and IVF protocols should be tailored to specific patients or patient populations. Treatment approaches should be directed toward individual patient cases. In addition, we suggest considering a new initial step in approach to patients with RIF, individualized planned activities to activate the brain's reward system in attempt to improve immunological balance in the body.  相似文献   

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The article provides a perspective on the challenges for biostatistics as well as on contributions that biostatisticians are making and can make to medical product development and regulation and what the future might be in these areas. The current environment in the United States for pharmaceutical development and regulation is discussed along with the expectations that the public has for how medical products should contribute to public heath. The globalization of research and the use of study designs that incorporate multi-regional populations present new challenges for design and inference. The emerging interest in and development of the science of safety assessment and quantitative approaches to risk evaluation is considered. Guidance development, especially in the area of clinical trials design, continues to be one of the needs that FDA is asked to meet. Guidance development is proceeding for non-inferiority study designs, adaptive designs, multiple endpoints in clinical trials, and missing outcome data in clinical trials. Biostatisticians will be asked and challenged to take on leadership roles in new areas such as personalized medicine, biomarker and genomics, development of new tools for visual display of clinical data, quality assurance and monitoring in clinical trials.  相似文献   

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The viability, cellular uptake and subcellular distribution of heavy metal Hg, were determined in human mammary cell lines (MCF-7, MDA-MB-231 and MCF-10A). It was observed that Hg had the capacity of being excluded from the cells with a different type of possible transporters. MCF-7 cells showed the lowest viability, while the other two cell lines were much more resistant to Hg treatments. The intracellular concentration of Hg was higher at lower exposure times in MCF-10A cells and MCF-7 cells; but as the time was increased only MDA-MB-231 showed the capacity to continue introducing the metal. In MCF-7 and MCF-10A cells the subcellular distribution of Hg was higher in cytosolic fraction than nucleus and membrane, but MDA-MB-231 showed membrane and nucleus fraction as the enriched one. The analysis of RNA-seq about the genes or family of genes that encode proteins which are related to cytotoxicity of Hg evidenced that MCF-10A cells and MCF-7 cells could have an active transport to efflux the metal. On the contrary, in MDA-MB-231 no genes that could encode active transporters have been found.  相似文献   

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Zhang J  Wu X  Zhang SQ 《Biotechnology letters》2008,30(12):2157-2163
Antibacterial peptide, CM4 (ABP-CM4), a 35 amino acid peptide from Chinese silkworm—Bombyx mori, displayed a strong antifungal activity against Aspergillus niger, Trichoderma viride and Gibberella saubinetii. Scanning electron microcopy showed that the morphology of conidia became more irregular and swelled when treated with ABP-CM4 at its minimal inhibitory concentration (MIC) of 8 μM. A cell wall regeneration assay indicated that the plasma membrane was the prime target of ABP-CM4 action. Confocal laser scanning microscopy showed that the cytoskeleton of A. niger was destroyed when treated with ABP-CM4 at 8 μM. Furthermore, transmission electron microscopy showed that the membrane and the cellular organelles of fungus were disrupted and there were many vacuoles in the fungal cellular space after the treatment with ABP-CM4. A gel-retardation assay showed that ABP-CM4 bound the DNA of A. niger. Our results suggest that ABP-CM4 exerts its antifungal activity by disrupting the structure of cell membranes and the cytoskeleton and interacts with the organelles, such as the mitochondrion and with the DNA in the fungal cell, subsequently resulting in cell death.  相似文献   

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This study was designed to identify the rare?type?ABO?blood?groups, B(A) 02, from Eastern China. Three samples with discordant serological results during routine blood type identification and four samples from one sample’ family were selected. All of them were detected by serological method. The exon 6 and 7 of the ABO genes were amplified by PCR and sequenced. They were typed as AsubB by serology and as BO by genotype. In AsubB samples, nt 700C>G mutation was detected in B gene, which was previously defined as B(A)02 alleles. In these seven samples, six showed B(A)02/O01 and one showed B(A)02/O02.B(A)02 allele was found to be more common in this study than B(A)04 which is considered to be more frequent than B(A)02. The careful identification of rare blood types is important for the safety of clinical blood transfusion.  相似文献   

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The growth of a first filial generation (F1) of OF1 mice was studied following chronic exposure of their mothers and themselves to a magnetic field of 15?μT (rms) and 50?Hz. The parental generation (F0) remained for 98 days in this field, after that time they were mated, went through pregnancy, birth, lactation, and the weaning of their offspring in this field. The latter remained exposed to this field until reaching adulthood (220 days). Control animals were treated in the same way but were exposed only to the Earth's magnetic field. The growth data for the offspring were analyzed using a generalization of Koop's equation. Using this model, four phases were identified: lactation growth acceleration, post-weaning growth acceleration, growth stabilization, and a stationary phase. Exposure to the artificial magnetic field was associated with a marked increase in maximum growth rate in the exposed animals during the post-weaning growth acceleration phase, and with a reduction in mass gain in the F1 mice (especially in males) during the third of these phases. In addition, the growth stabilization phase was more extended in exposed females and shorter in exposed males than in the control animals. Furthermore, statistically significant differences were seen between the mean body masses of exposed and control F1 males from 49-123 days. Exposure to the artificial magnetic field might have been associated with the stimulated growth rate seen over the noticeably shortened second and third growth phases (leaving these animals lighter by the stationary phase compared to controls) and a possible acceleration of aging. Both processes could be responsible for the stationary phase being reached at an earlier age, especially in males.  相似文献   

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Morgan-Kiss RM  Ivanov AG  Huner NP 《Planta》2002,214(3):435-445
State I-State II transitions were monitored in vivo and in vitro in the Antarctic, psychrophillic, green alga, Chlamydomonas subcaudata, as changes in the low-temperature (77 K) chlorophyll fluorescence emission maxima at 722 nm (F722) relative to 699 nm (F699). As expected, the control mesophillic species, Chlamydomonas reinhardtii, was able to modulate the light energy distribution between photosystem II and photosystem I in response to exposure to four different conditions: (i) dark/anaerobic conditions, (ii) a change in Mg2+ concentration, (iii) red light, and (iv) increased incubation temperature. This was correlated with the ability to phosphorylate both of its major light-harvesting polypeptides. In contrast, exposure of C. subcaudata to the same four conditions induced minimum alterations in the 77 K fluorescence emission spectra, which was correlated with the ability to phosphorylate only one of its major light-harvesting polypeptides. Thus, C. subcaudata appears to be deficient in the ability to undergo a State I-State II transition. Functionally, this is associated with alterations in the apparent redox status of the intersystem electron transport chain and with higher rates of photosystem I cyclic electron transport in the psychrophile than in the mesophile, based on in vivo P700 measurements. Structurally, this deficiency is associated with reduced levels of Psa A/B relative to D1, the absence of specific photosystem I light-harvesting polypeptides [R.M. Morgan et al. (1998) Photosynth Res 56:303-314] and a cytochrome b6/f complex that exhibits a form of cytochrome f that is approximately 7 kDa smaller than that observed in C. reinhardtii. We conclude that the Antarctic psychrophile, C. subcaudata, is an example of a natural variant deficient in State I-State II transitions.  相似文献   

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正约翰英纳斯中心的Tony Miller博士与南京农业大学的研究人员合作开发出了能够控制自身pH值的水稻,这种水稻品种能够从土壤中吸收更多的氮、铁和磷,产量提高了54%。研究人员一直研究水稻如何在不断变化的环境中维持pH值,他们发现,  相似文献   

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Bottlenose dolphins (Tursiops truncatus) produce individually distinctive signature whistles that broadcast the identity of the caller. Unlike voice cues that affect all calls of an animal, signature whistles are distinct whistle types carrying identity information in their frequency modulation pattern. Signature whistle development is influenced by vocal production learning. Animals use a whistle from their environment as a model, but modify it, and thus invent a novel signal. Dolphins also copy signature whistles of others, effectively addressing the whistle owner. This copying occurs at low rates and the resulting copies are recognizable as such by parameter variations in the copy. Captive dolphins can learn to associate novel whistles with objects and use these whistles to report on the presence or absence of the object. If applied to signature whistles, this ability would make the signature whistle a rare example of a learned referential signal in animals. Here, we review the history of signature whistle research, covering definitions, acoustic features, information content, contextual use, developmental aspects, and species comparisons with mammals and birds. We show how these signals stand out amongst recognition calls in animals and how they contribute to our understanding of complexity in animal communication.  相似文献   

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Gigantonoclea guizhouensis Gu et Zhi 的叶部解剖研究   总被引:3,自引:1,他引:2  
一、材料来源和研究方法解剖研究所用的D-1标本是笔者于1984年5月在贵州水城大河边煤矿二采区新开辟的运输巷侧壁砂岩中采到的,其层位经对比与田宝霖和张连武(1980)描述的水城汪家寨矿区综合地层柱中龙潭组下部第8分层的中部砂岩相当。该叶片沉积时受水流冲击,以中脉为对称轴向远轴侧对折成约20°角状(图版Ⅰ,图2)。  相似文献   

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This review focuses on studies of water movement across biological membranes performed over the last 50 years. Different scientific approaches had tried to elucidate such intriguing mechanism, from hypotheses emphasizing the role of the lipid bilayer to the cloning of aquaporins, the ubiquitous proteins described as specific water channels. Pioneering and clarifying biophysical work are reviewed beside results obtained with the help of recent sophisticated techniques, to conclude that great advances in the subject live together with old questions without definitive answers.  相似文献   

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