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1.
The interactions of adenine and thymine with and adsorption on zeolites were studied using different techniques. There were two main findings. First, as shown by X-ray diffractometry, thymine increased the decomposition of the zeolites (Y, ZSM-5) while adenine prevented it. Second, zeolite Y adsorbed almost the same amount of adenine and thymine, thus both nucleic acid bases could be protected from hydrolysis and UV radiation and could be available for molecular evolution. The X-ray diffractometry and SEM showed that artificial seawater almost dissolved zeolite A. The adsorption of adenine on ZSM-5 zeolite was higher than that of thymine (Student-Newman-Keuls test-SNK p<0.05). Adenine was also more greatly adsorbed on ZSM-5 zeolite, when compared to other zeolites (SNK p<0.05). However the adsorption of thymine on different zeolites was not statistically different (SNK p>0.05). The adsorption of adenine and thymine on zeolites did not depend on pore size or Si/Al ratio and it was not explained only by electrostatic forces; rather van der Waals interactions should also be considered.  相似文献   

2.
Seeds contain the embryo as a new plant in miniature and have two major functions, reproduction and dispersal. Seed formation completes the process of plant reproduction and, with seed germination, the next plant generation starts. Given the ever-increasing environmental pollution with metal(loid)s, it is perhaps surprising that relatively few reports detail the impacts of metals on seed metabolism, viability and germination in comparison to the numerous publications on the effects of metals in vegetative tissues, particularly roots and shoots. This review provides information on metal(loid) homeostasis, detoxification and tolerance in relation to seed metabolism and performance. The delivery of metals from the mother plant into seeds and their implications on seed development are discussed, as are their uptake upon seed imbibition and subsequent effects on seed germination. Implications for seeds and seedlings on the biochemical and molecular level are discussed and finally, applied aspects are considered regarding the use of seeds for soil and water purification, and in phytoremediation programmes. We conclude with a perspective on future metal research in relation to seed biology.  相似文献   

3.
Effective breast cancer management and decreasing breast cancer fatalities is contingent upon reliable diagnostic procedures and treatment modalities, including those based on ionizing radiation. On the one hand, ionizing radiation is widely used for cancer diagnostics and therapy, on the other hand it is genotoxic cancer-causing agent. Here we discuss recent studies on the effects of low (diagnostic) and high (treatment) doses of ionizing radiation on healthy breast cells, breast cancer cells, and cancer cells resistant to common drug therapies.  相似文献   

4.
The Phytophagous Insects Data Base (PIDB) was used to summarize information about 6933 species of British insects/mites and their food-plant families. Total species in 183 insect families on 127 vascular plant families were correlated with numbers of plant species in each family in Britain and Europe, accounting for 41.8% of the variation. Families with trees had more insects, while ferns and aquatic, uncommon and ephemeral plants, particularly orchids, had fewer. Seven individual insect families were analysed separately: Aphididae were more closely correlated with plant species numbers than were the more polyphagous Geometridae. Agromyzidae were uncommon on families with trees. Of insect species 75.8% fed on only one plant family and 10.1% were recorded on two families. Species feeding on three families or more were considered to be polyphagous. In the 30 largest insect families, eight had species feeding on only one plant family, while 12 had more than 20% of their species polyphagous. Proportions of family-restricted insects were high on Pinaceae, Gramineae and Compositae, but low on Corylaceae, Primulaceae and Tiliaceae. More pest species were polyphagous. Polyphagy was related to large larvae, larvae overwintering, wood-feeding, ephemeral food sources, poor dispersal abilities and omnivory. Some polyphagous species might be actively evolving in exploitation of vacant niches, leading to later progressive specialization to food-plants.  相似文献   

5.
1. Turtle heart and intestine acetone powders were extracted with an acetone-water-HCl mixture. An acid acetone powder resulted by adding a copious volume of acetone to the extract. The powder was subjected to gel filtration on Sephadex G-25 and ion exchange chromatography on CM-cellulose. 2. In turtle heart, corticotropin-like bioactivity was distributed among chromatographic fractions (derived from material unretarded on Sephadex G-25) unadsorbed and adsorbed on CM-cellulose. The highest opiate receptor binding activity and beta-endorphin-like immunoreactivity were adsorbed on CM-cellulose. 3. In turtle intestine, corticotropin-like bioactivity was absent. Opiate receptor binding activity was present in fractions unretarded as well as in fractions retarded on Sephadex G-25, indicating a molecular weight of greater and smaller than 5000 respectively. 4. The highest opiate receptor binding activity and beta-endorphin-like immunoreactivity were found in a fraction adsorbed on CM-cellulose.  相似文献   

6.
Rheumatic diseases in women of childbearing years may necessitate drug treatment during a pregnancy, to control maternal disease activity and to ensure a successful pregnancy outcome. This survey is based on a consensus workshop of international experts discussing effects of anti-inflammatory, immunosuppressive and biological drugs during pregnancy and lactation. In addition, effects of these drugs on male and female fertility and possible long-term effects on infants exposed to drugs antenatally are discussed where data were available. Recommendations for drug treatment during pregnancy and lactation are given.  相似文献   

7.
本文对两种载脂蛋白B的相对分子质量及其氨基酸残基数进行了详细的考证,指出国内外常见的生物化学或分子生物学教材/参考书在这些方面的若干疏误,初步分析了个中缘由,并就教材的编写和使用提出一些建议。  相似文献   

8.
Aim Conservation of species is an ongoing concern. Location Worldwide. Methods We examined historical extinction rates for birds and mammals and contrasted island and continental extinctions. Australia was included as an island because of its isolation. Results Only six continental birds and three continental mammals were recorded in standard databases as going extinct since 1500 compared to 123 bird species and 58 mammal species on islands. Of the extinctions, 95% were on islands. On a per unit area basis, the extinction rate on islands was 177 times higher for mammals and 187 times higher for birds than on continents. The continental mammal extinction rate was between 0.89 and 7.4 times the background rate, whereas the island mammal extinction rate was between 82 and 702 times background. The continental bird extinction rate was between 0.69 and 5.9 times the background rate, whereas for islands it was between 98 and 844 times the background rate. Undocumented prehistoric extinctions, particularly on islands, amplify these trends. Island extinction rates are much higher than continental rates largely because of introductions of alien predators (including man) and diseases. Main conclusions Our analysis suggests that conservation strategies for birds and mammals on continents should not be based on island extinction rates and that on islands the key factor to enhance conservation is to alleviate pressures from uncontrolled hunting and predation.  相似文献   

9.
In this study, the antimicrobial effects of monophosphazenes such as SM, BOMPHOS, and PHOMPHOS were examined on bacterial and yeast strains. In addition, the biological effects of these compounds were tested on the Saccharomyces cerevisiae and Candida albicans cells. The SM has an antimicrobial effect on the bacterial and yeast strains within the range of 100 and 1500 μg. When the concentration was increased, the inhibition zone expanded on the growth media (P < 0.01; P < 0.001). Like SM, BOMPHOS molecule has antimicrobial activity on the bacterial and yeast cells. The most effective concentrations of BOMPHOS on the microorganisms were observed by 1500 μg (P < 0.001). The PHOMPHOS did not effect on the bacterial and yeast cells between 100 and 1000 range, but it has an antimicrobial effect in 1500 μg. In vitro media, the biological effects of these molecules were compared with vitamin E, melatonin, and fish oil on the yeast cells. In S. cerevisiae growth media, the cell densities were increased SM, BOMPHOS, and PHOMPHOS after 20, 30, and 45 h. The highest increase in the cell density were observed in media of BOMPHOS. In C. albicans growth media, the cell density was increased by melatonin after 20, 30, and 45 h, but were decreased by other supplemental groups. Lipid level of S. cerevisiae was reduced by administered 300 and 1000 μg vitamin E and fish oil (P < 0.01). In addition, the lipid level of the same yeast cell were diminished by the 1000 μg melatonin and 300 μg PHOMPHOS (P < 0.05, P < 0.01). The lipid level of C. albicans were increased by vitamin E and BOMPHOS and fish oil, but was decreased with PHOMPHOS (P < 0.01). In conclusion, while high concentration of PHOMPHOS has antimicrobial effects on the bacterial and yeast cells, the SM and BOMPHOS have antimicrobial effects in all the concentrations. PHOMPHOS decreased the lipid level of C. albicans, but BOMPHOS increased in the the same yeast cell. In addition, the antioxidants such as vitamin E, melatonin, and fish oils have affected on the lipid synthesis of yeast cells. Copyright 2000 Academic Press.  相似文献   

10.
We have measured by radioimmunoassay the concentration and production of 5(S)-hydroxy-6,8,11,14-eicosatetraenoic acid (5-HETE), a metabolite in the lipoxygenase pathway, and PGs in different uterine compartments, and blastocysts during the preimplantation period in the rabbit. The production is defined as the synthesis minus the metabolism for a defined period of time. The pattern of uterine PGF production on days 5-6.5 was quite similar for the whole uterus and the myometrium showing a peak production on Day 6. The concentration and production of PGF were always higher in the endometrium. While significant production of PGE was noticed in the whole uterus on days 5-6 and in the myometrium on Day 6, the endometrium showed some production on these days. On the contrary, absolutely no production of this PG was observed in the endometrium on Day 6.5. The concentration and production of 6-keto-PGF1 alpha were always lower in the endometrium than those observed in the myometrium or the whole uterus. While highest production of this PG was found to be on Day 6.5 in the whole uterus and on Day 5 in the endometrium, the production in the myometrium remained constant on all days examined. The production of 5-HETE in the endometrium was noticeable on Days 5-6.5, in the whole uterus on Days 5 and 6.5, and in the myometrium only on Day 6.5. However, the concentrations of 5-HETE showed a tendency to be higher at 2 h than at 0 h in these compartments on Days 5-6.5. Furthermore, a linear increase in 5-HETE levels both at 0 h and 2 h was observed in the endometrium on Days 5-6.5; no such difference in mean 5-HETE level was noted in the whole uterus or myometrium on any of these days. The production of 5-HETE in the blastocyst was noted only on Day 5. The results not only demonstrate the presence of both the cyclooxygenase and the lipoxygenase pathways in the preimplantation rabbit uterus and blastocyst, their differential operation in various compartments of the uterus on various days of early pregnancy suggests an integrated role for these mediators in embryo-uterine interaction during implantation.  相似文献   

11.
Natural and intercalated Wyoming montmorillonite (MMT) with the tetramethylammonium (TMA) cations were used for the adsorption of phenol and aniline. Laboratory experiments characterised by adsorption isotherms were compared with the results of molecular modelling simulations. Aniline adsorbed itself strongly on MMT; while using the TMA intercalates (TMA-MMT), its adsorption decreased. On the contrary, the adsorption of phenol on TMA-MMT was moderately higher than on the MMT surface. The MMT surface models were described by empirical force field used in molecular mechanics and dynamics. The Burchart–Universal force field was used in the Cerius2 modelling environment. The modelling results revealed the important role of water forming a moderately concentrated layer on the pure MMT surface. Water molecules enable the adsorption of aniline on MMT and, on the contrary, repel phenol molecules from MMT. In the case of TMA-MMT, lower amount of water near a silicate layer caused decrease in the aniline adsorption and, on the contrary, increase in the phenol adsorption.  相似文献   

12.
In this study, the antimicrobial effects of monophosphazenes such as SM ipemphos and amphos were examined on bacterial and yeast strains. In addition, the biological effects of these compounds were tested on the lipid level of Saccharomyces cerevisiae and Candida albicans cells. The SM has an antimicrobial effect on the bacterial and yeast strains within the range of 100 and 1500 microg. When the concentration was increased, the inhibition zone expanded on the growth media ( p < 0.01; p < 0.001). The ipemphos did not affect the bacterial and yeast cells in the 100 and 600 microg range. In addition, the amphos did not show an antimicrobial effect on the bacterial cells between 100 and 300 microg or on yeast cells at any of the administered concentrations. In vitro media, the biological effects of these molecules were compared with vitamin E, melatonin and fish oil on the yeast cells. We have found that monophosphazenes have growth effects on the cells in vitro media. The lipid level of S. cerevisiae cells was decreased by 300 microg doses of vitamin E, fish oil, and ipemphos (respectively; p < 0.05, p < 0.01, and p < 0. 001). In addition, the lipid levels of the same yeast cells were depressed by 1000-microg doses in all supplemented groups. However, it was observed that the highest decrease in lipid level of S. cerevisiae cells occurred in the amphos group ( p < 0.001). The lipid levels of the C. albicans cells were significantly reduced ( p < 0.01) by 300 microg of amphos and melatonin. In contrast, the vitamin E and fish oil significantly raised ( p < 0.01; p < 0.001) the lipid level of the same yeast cell, as compared with the control. In addition, the lipid level of these cells was increased by administration of 1000 microg vitamin E, and melatonin ( p < 0.01). In conclusion, while high concentrations of ipemphos and amphos have an antimicrobial effect on bacterial and yeast cells, amphos did not affect the yeast cells. While ipemphos and amphos increased cell growth in media, they reduced the lipid level of C. albicans and S. cerevisiae. In addition, the antioxidants such as vitamin E, melatonin, and fish oils affected the lipid level of yeast cells.  相似文献   

13.
Hydrolytic enzymes and haemolysins are important extracellular substances produced by many bacteria. We investigated 57 K. pneumoniae strains and 40 K. oxytoca strains isolated from clinical materials. We estimated the ability to produce: proteases hydrolyzing milk powder, caseinase, gelatinase, elastase, lecithinase, lipases, DNase and haemolysins on human, sheep and horse erythrocytes on TSA medium with or without 5% Egg Yolk. We detected that K. oxytoca strains produced proteases hydrolyzing milk powder (37.5%), caseinase (15.0%) and gelatinase (17.5%) more frequently than K. pneumoniae strains (respectively 21.0%, 5.3%, 8.9%). None of the analysed Klebsiella spp. strains produced elastase. Only K. pneumoniae strains produced lecithinase (5.3%). Lipases hydrolyzing Tween were produced from 3.5% (for Tween 60 and 80) to 7.0% (for Tween 20). Among K. oxytoca strains only one (2.5%) hydrolyzing Tween 20. DNase was produced by 38.6% of K. pneumoniae strains and by 27.5% K. oxytoca strains. Haemolytic properties on human erythrocytes were detected in 5.3% K. pneumoniae strains on TSA medium and 29,8% on medium with Egg Yolk. In K. oxytoca strains haemolytic properties on human erythrocytes were detected only on medium with Egg Yolk (12.5%). Haemolytic properties on sheep erythrocytes were detected respectively in 21.0% and 22.8% K. pneumoniae strains and in 7.5% K. oxytoca strains on each medium. Haemolytic properties on horse erythrocytes were detected respectively in 33.4% and 52.6% K. pneumoniae strains and in 15.0% and 20.0% K. oxytoca strains.  相似文献   

14.
The modeling relation and models of complex systems expressed by non-integrable constraints were developed during ca. 1970-1987, when I worked most closely with Robert Rosen. I contrast the modeling relation within the organism itself as a necessary condition for life and evolution, as Rosen developed it in his fundamental work 'Anticipatory Systems', with the modeling relation within our brain as a necessary condition for understanding life, as Rosen developed it in 'Life Itself'. Our approaches to the modeling relation were complementary. Rosen focused on the formal relational conditions necessary for life, and on the limitations that formal mathematical-symbol systems impose on our models. I focused on the physical conditions necessary for these abstract relations to be realized, and on the symbolic control in organisms that allows open-ended evolution. I contrast Rosen's views on physics and evolution in 'Anticipatory Systems' and later papers with his views in 'Life Itself', and I speculate on why they differ so greatly.  相似文献   

15.
We have measured by radioimmunoassay the concentration and production of 5(S)-hydroxy-6,8,11,14-eicosatetraenoic acid (5-HETE), a metabolite in the lipoxygenase pathway, and PGs in different uterine compartments, and blastocysts during the preimplantation period in the rabbit. The production is defined as the synthesis minus the metabolism for a defined period of time. The pattern of uterine PGF production on days 5–6.5 was quite similar for the whole uterus and the myometrium showing a peak production on Day 6. The concentration and production of PGF were always higher in the endometrium. While significant production of PGE was noticed in the whole uterus on days 5–6 and in the myometrium on Day 6, the endometrium showed some production on these days. On the contrary, absolutely no production of this PG was observed in the endometrium on Day 6.5. The concentration and production of 6-keto-PGF were always lower in the endometrium than those observed in the myometrium or the whole uterus. While highest production of this PG was found to be on Day 6.5 in the whole uterus and on Day 5 in the endometrium, the production in the myometrium remained constant on all days examined. The production of 5-HETE in the endometrium was noticeable on Days 5–6.5, in the whole uterus on Days 5 and 6.5, and in the myometrium only on Day 6.5. However, the concentrations of 5-HETE showed a tendency to be higher at 2 h than at 0 h in these compartments on Days 5–6.5. Furthermore, a linear increase in 5-HETE levels both 0 h and 2 h was observed in the endometrium on Days 5–6.5; no such differences in mean 5-HETE level was noted in the whole uterus or myometrium on any of these days. The production of 5-HETE in the blastocyst was noted only on Day 5. The results not only demonstrate the presence of both the cyclo-oxygenase and the lipoxygenase pathways in the preimplantation rabbit uterus and blastocyst, their differential operation in various compartments of the uterus on various days of early pregnancy suggests an integrated role for these mediators in embryo-uterine interaction during implantation.  相似文献   

16.
The interferons (IFNs) were originally described over 50 years ago, identified by their ability to confer viral resistance to cells. We now know that they are much more than just anti-viral cytokines collectively having roles in both innate and adaptive immune responses, in tumor surveillance and defense, and modulation of immune cell function. Three types of IFN have now been described, simply referred to as type I, II and III. Distinguishable by the unique receptors that they rely on for signal transduction, the three types of IFN have specific and varied roles in the maintenance of human health and defense against pathogens. In mounting an IFN-mediated immune response, the human body has developed the ability to regulate IFN-mediated signal transduction. Like all cytokines, the ability of a cell to respond to IFN is completely dependent on the presence of its cognate receptor on the surface of the target cell. Thus, one of the major mechanisms used by the human body to regulate the strength and duration of the IFN response is through regulation of receptor levels, thereby altering the cytokine-specific responsiveness of the target cell. This review will discuss the receptor system utilized by the type I IFNs and compare it with that of the type II and III IFNs, which also regulate immune responses through controlling receptor level on the cell surface.  相似文献   

17.
Davis GJ 《Plant physiology》1967,42(5):667-668
Proserpinaca palustris L. produced juvenile leaves on 8-hour photoperiods, adult leaves on 12-hour photoperiods, and adult leaves and flowers on 14-hour photoperiods. Treatment of plants growing on 8- and 14-hour photoperiods with gibberellic acid caused stem elongation and inhibited flowering. The treated plants on 8-hour photoperiods produced adult-like leaves.  相似文献   

18.
新疆北疆山区具有非常丰富的小浆果资源,但开发利用尚处初级阶段。对新疆北疆小浆果的分布现状及保护、合理开发利用和人工栽培状况进行了初步探讨,提出了在山区发展小浆果类经济树种的初步建议。  相似文献   

19.
Relative to the West Indies, the ecology and evolution of anoles inhabiting islands off Central and South America have received little attention. The paucity of studies on continental islands has limited our ability to generalize and extend results based on the West Indian paradigm, as well as our understanding of the profound differences between the adaptive radiations of continental vs. Greater Antillean anoles. Here we compare the morphological, ecological, behavioural and genetic divergence between Anolis nebulosus populations inhabiting a small island in the Bay of Chamela, Mexico, and a nearby mainland forest. Notably, the two populations exhibit intra‐sexual dimorphism with respect to head and limb sizes, the first such polymorphism documented for an Anolis species. We also compare the shape of island and mainland A. nebulosus with each other, the six West Indian ecomorphs and a hypothetical generalist species. Finally, we address the generalist convergence hypothesis for anoles on single species islands. We conclude that convergence on a generalist morphology is widespread among solitary anoles in the West Indies. We present data on a limited sample of solitary anoles with mainland ancestors that suggest a parallel convergence on a similar generalist morphology, probably due to similar adaptive landscapes shaped by selective forces common to small island environments.  相似文献   

20.
This article reviews and updates data on macro and trace elements and radionuclides in edible wild-grown and cultivated mushrooms. A huge biodiversity of mushrooms and spread of certain species over different continents makes the study on their multi-element constituents highly challenging. A few edible mushrooms are widely cultivated and efforts are on to employ them (largely Agaricus spp., Pleurotus spp., and Lentinula edodes) in the production of selenium-enriched food (mushrooms) or nutraceuticals (by using mycelia) and less on species used by traditional medicine, e.g., Ganoderma lucidum. There are also attempts to enrich mushrooms with other elements than Se and a good example is enrichment with lithium. Since minerals of nutritional value are common constituents of mushrooms collected from natural habitats, the problem is however their co-occurrence with some hazardous elements including Cd, Pb, Hg, Ag, As, and radionuclides. Discussed is also the problem of erroneous data on mineral compounds determined in mushrooms.  相似文献   

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