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21.
Avraham Geier Rachel Beery Michal Haimsohn Rina Hemi Zvi Malik Avraham Karasik 《In vitro cellular & developmental biology. Animal》1994,30(12):867-874
Summary The ability of epidermal growth factor (EGF), insulinlike growth factor-1 (IGF-1), insulin, 12-O-tetradecanoylphorbol-13-acetate
(TPA), and aurintricarboxylic acid (ATA) to protect the human breast cancer cell line MDA-231 from death induced by the anticancer
drug adriamycin was investigated. Cell death was induced in the MDA-231 cells either by a short-time exposure to a high dose
of adriamycin (2 μg · ml−1 · 1 h−1) and further culturing in the absence of the drug, or by continuous exposure to a low dose of adriamycin (0.3μg/ml). Cell death was evaluated after 48 h of incubation by several techniques (trypan blue dye exclusion, lactic dehydrogenase
activity, cellular ATP content, transmission electron microscopy, and DNA fragmentation). EGF, TPA, and ATA, each at an optimal
concentration of 20 ng/ml, 5 ng/ml, and 100μg/ml respectively, substantially enhanced survival of cells exposed either to a high or low dose of adriamycin. Neither IGF-1
nor insulin, each at concentrations of 20 ng/ml, had an effect on cell survival. The three survival factors enhanced protein
synthesis in the untreated cells and attenuated the continuous decrease in protein synthesis in the adriamycin-treated cells.
Moreover, the three survival factors protected the MDA-231 cells from death in the absence of protein synthesis (cycloheximide
30μg/ml). These results suggest that EGF, TPA, and ATA promote survival of adriamycin pretreated cells by at least two mechanisms:
enhancement of protein synthesis and by a protein synthesis independent process, probably a posttranslational modification
effect. 相似文献
22.
23.
Jan Tumajer Krešimir Begović Vojtěch Čada Michal Jenicek Jelena Lange Jiří Mašek Ryszard J. Kaczka Miloš Rydval Miroslav Svoboda Lukáš Vlček Václav Treml 《Global Change Biology》2023,29(2):462-476
Radial tree growth is sensitive to environmental conditions, making observed growth increments an important indicator of climate change effects on forest growth. However, unprecedented climate variability could lead to non-stationarity, that is, a decoupling of tree growth responses from climate over time, potentially inducing biases in climate reconstructions and forest growth projections. Little is known about whether and to what extent environmental conditions, species, and model type and resolution affect the occurrence and magnitude of non-stationarity. To systematically assess potential drivers of non-stationarity, we compiled tree-ring width chronologies of two conifer species, Picea abies and Pinus sylvestris, distributed across cold, dry, and mixed climates. We analyzed 147 sites across the Europe including the distribution margins of these species as well as moderate sites. We calibrated four numerical models (linear vs. non-linear, daily vs. monthly resolution) to simulate growth chronologies based on temperature and soil moisture data. Climate–growth models were tested in independent verification periods to quantify their non-stationarity, which was assessed based on bootstrapped transfer function stability tests. The degree of non-stationarity varied between species, site climatic conditions, and models. Chronologies of P. sylvestris showed stronger non-stationarity compared with Picea abies stands with a high degree of stationarity. Sites with mixed climatic signals were most affected by non-stationarity compared with sites sampled at cold and dry species distribution margins. Moreover, linear models with daily resolution exhibited greater non-stationarity compared with monthly-resolved non-linear models. We conclude that non-stationarity in climate–growth responses is a multifactorial phenomenon driven by the interaction of site climatic conditions, tree species, and methodological features of the modeling approach. Given the existence of multiple drivers and the frequent occurrence of non-stationarity, we recommend that temporal non-stationarity rather than stationarity should be considered as the baseline model of climate–growth response for temperate forests. 相似文献
24.
Krešimir Begović Jonathan S. Schurman Marek Svitok Jakob Pavlin Thomas Langbehn Kristyna Svobodová Martin Mikoláš Pavel Janda Michal Synek William Marchand Lucie Vitková Daniel Kozák Ondrej Vostarek Vojtech Čada Radek Bače Miroslav Svoboda 《Global Change Biology》2023,29(1):143-164
In a world of accelerating changes in environmental conditions driving tree growth, tradeoffs between tree growth rate and longevity could curtail the abundance of large old trees (LOTs), with potentially dire consequences for biodiversity and carbon storage. However, the influence of tree-level tradeoffs on forest structure at landscape scales will also depend on disturbances, which shape tree size and age distribution, and on whether LOTs can benefit from improved growing conditions due to climate warming. We analyzed temporal and spatial variation in radial growth patterns from ~5000 Norway spruce (Picea abies [L.] H. Karst) live and dead trees from the Western Carpathian primary spruce forest stands. We applied mixed-linear modeling to quantify the importance of LOT growth histories and stand dynamics (i.e., competition and disturbance factors) on lifespan. Finally, we assessed regional synchronization in radial growth variability over the 20th century, and modeled the effects of stand dynamics and climate on LOTs recent growth trends. Tree age varied considerably among forest stands, implying an important role of disturbance as an age constraint. Slow juvenile growth and longer period of suppressed growth prolonged tree lifespan, while increasing disturbance severity and shorter time since last disturbance decreased it. The highest age was not achieved only by trees with continuous slow growth, but those with slow juvenile growth followed by subsequent growth releases. Growth trend analysis demonstrated an increase in absolute growth rates in response to climate warming, with late summer temperatures driving the recent growth trend. Contrary to our expectation that LOTs would eventually exhibit declining growth rates, the oldest LOTs (>400 years) continuously increase growth throughout their lives, indicating a high phenotypic plasticity of LOTs for increasing biomass, and a strong carbon sink role of primary spruce forests under rising temperatures, intensifying droughts, and increasing bark beetle outbreaks. 相似文献
25.
Shannen Grandy Michal Scur Kathleen Dolan Rhea Nickerson Zhenyu Cheng 《Environmental microbiology》2023,25(10):1765-1784
Using model systems in infection biology has led to the discoveries of many pathogen-encoded virulence factors and critical host immune factors to fight pathogenic infections. Studies of the remarkable Pseudomonas aeruginosa bacterium that infects and causes disease in hosts as divergent as humans and plants afford unique opportunities to shed new light on virulence strategies and host defence mechanisms. One of the rationales for using model systems as a discovery tool to characterise bacterial factors driving human infection outcomes is that many P. aeruginosa virulence factors are required for pathogenesis in diverse different hosts. On the other side, many host signalling components, such as the evolutionarily conserved mitogen-activated protein kinases, are involved in immune signalling in a diverse range of hosts. Some model organisms that have less complex immune systems also allow dissection of the direct impacts of innate immunity on host defence without the interference of adaptive immunity. In this review, we start with discussing the occurrence of P. aeruginosa in the environment and the ability of this bacterium to cause disease in various hosts as a natural opportunistic pathogen. We then summarise the use of some model systems to study host defence and P. aeruginosa virulence. 相似文献
26.
Markéta Ondračková Maria Yu Tkachenko Veronika Bartáková Anna Bryjová Michal Janáč Grzegorz Zięba Kacper Pyrzanowski Yuriy Kvach 《Journal of fish biology》2023,102(2):426-442
In Poland, distribution of non-native pumpkinseed Lepomis gibbosus (Centrarchidae) is strictly limited to the Oder river basin, where it was introduced in the early 20th century. Recently, several populations have been found in waterbodies adjacent to the Oder, particularly in its lower reaches. In this study, we compare the genetic relatedness of populations in the Oder basin with other European populations using nuclear (microsatellite) and mitochondrial (partial cytochrome c oxidase subunit I; cox1) markers. Microsatellite analysis indicated that four populations in the lower Oder form a separate cluster, while one in the middle Oder clustered with Danubian populations, from where probably having been introduced. Microsatellite data suggested that the lower Oder populations differ from other non-native European populations, making it impossible to estimate the source of introduction. Nevertheless, analysis of cox1 indicated that Oder pumpkinseeds belong to the same haplotype as the vast majority of European populations. Parasitological examination confirmed the presence of two North American species, the monogenean Onchocleidus dispar and trematode Posthodiplostomum centrarchi, in the lower Oder, both previously unknown in the region. Fifteen other parasite species were acquired, including glochidia of invasive Sinanodonta woodiana. In the middle Oder, parasite infection was more limited. Fish from the Gryfino Canal, considered one of the most invasive populations in Europe, showed the highest parasite abundance and diversity, and the highest somatic condition and growth rate due to warm water released from the Dolna Odra power plant. Our results highlight significant differences in somatic condition and parasite infection in long-established non-native pumpkinseed populations in the same river system, reflecting mainly environmental conditions. 相似文献
27.
L. Dugovičová L. Fojtík V. Novak Z. Gálová Z. Gálová M. Lejko I. Michalík J. Honza J. Minář J. Zehnálek A. Kostrej I. Kousalová M. Kováčová M. Lexa D. Miklovič M. Kováčová L. Nátr Z. Nátrová V. Novák Y. Kumar M. Novotná F. Plhák E. Tománková J. Zehnálek J. Černohorská M. Dvořák D. Harmancová 《Biologia Plantarum》1992,34(1):555
28.
Zbynek Lamplot Marek Sebela Michal Malon René Lenobel Karel Lemr Jan Havlis Pavel Pec Chunhua Qiao Lawrence M Sayre 《European journal of biochemistry》2004,271(23-24):4696-4708
1,5-diamino-2-pentyne (DAPY) was found to be a weak substrate of grass pea (Lathyrus sativus, GPAO) and sainfoin (Onobrychis viciifolia, OVAO) amine oxidases. Prolonged incubations, however, resulted in irreversible inhibition of both enzymes. For GPAO and OVAO, rates of inactivation of 0.1-0.3 min(-1) were determined, the apparent KI values (half-maximal inactivation) were of the order of 10(-5) m. DAPY was found to be a mechanism-based inhibitor of the enzymes because the substrate cadaverine significantly prevented irreversible inhibition. The N1-methyl and N5-methyl analogs of DAPY were tested with GPAO and were weaker inactivators (especially the N5-methyl) than DAPY. Prolonged incubations of GPAO or OVAO with DAPY resulted in the appearance of a yellow-brown chromophore (lambda(max) = 310-325 nm depending on the working buffer). Excitation at 310 nm was associated with emitted fluorescence with a maximum at 445 nm, suggestive of extended conjugation. After dialysis, the color intensity was substantially decreased, indicating the formation of a low molecular mass secondary product of turnover. The compound provided positive reactions with ninhydrin, 2-aminobenzaldehyde and Kovacs' reagents, suggesting the presence of an amino group and a nitrogen-containing heterocyclic structure. The secondary product was separated chromatographically and was found not to irreversibly inhibit GPAO. MS indicated an exact molecular mass (177.14 Da) and molecular formula (C10H15N3). Electrospray ionization- and MALDI-MS/MS analyses yielded fragment mass patterns consistent with the structure of a dihydropyridine derivative of DAPY. Finally, N-(2,3-dihydropyridinyl)-1,5-diamino-2-pentyne was identified by means of 1H- and 13C-NMR experiments. This structure suggests a lysine modification chemistry that could be responsible for the observed inactivation. 相似文献
29.
30.
Solid-phase synthesis of peptides was carried out using only the volume of the solvent included in the swollen solid-phase resin beads [inclusion volume synthesis]. This approach enables (i) the use of higher concentrations of activated amino acids, resulting in increased coupling rates, (ii) drastically decreased consumption of solvents, and (iii) the construction of multiple peptide synthesizers having virtually no reaction vessels. 相似文献