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981.
Background
Increasing evidence suggests an association between neuronal cell cycle (CCL) events and the processes that underlie neurodegeneration in Alzheimer’s disease (AD). Elevated levels of oxidative stress markers and mitochondrial dysfunction are also among early events in AD. Recent studies have reported the role of CCL checkpoint proteins and tumor suppressors, such as ATM and p53 in the control of glycolysis and oxidative metabolism in cancer, but their involvement in AD remains uncertain.Methods and Findings
In this postmortem study, we measured gene expression levels of eight CCL checkpoint proteins in the superior temporal cortex (STC) of persons with varying severities of AD dementia and compare them to those of cognitively normal controls. To assess whether the CCL changes associated with cognitive impairment in AD are specific to dementia, gene expression of the same proteins was also measured in STC of persons with schizophrenia (SZ), which is also characterized by mitochondrial dysfunction. The expression of CCL-checkpoint and DNA damage response genes: MDM4, ATM and ATR was strongly upregulated and associated with progression of dementia (cognitive dementia rating, CDR), appearing as early as questionable or mild dementia (CDRs 0.5–1). In addition to gene expression changes, the downstream target of ATM-p53 signaling - TIGAR, a p53-inducible protein, the activation of which can regulate energy metabolism and protect against oxidative stress was progressively decreased as severity of dementia evolved, but it was unaffected in subjects with SZ. In contrast to AD, different CCL checkpoint proteins, which include p53, CHEK1 and BRCA1 were significantly downregulated in SZ.Conclusions
These results support the activation of an ATM signaling and DNA damage response network during the progression of AD dementia, while the progressive decrease in the levels of TIGAR suggests loss of protection initiated by ATM-p53 signaling against intensifying oxidative stress in AD. 相似文献982.
Orconectes limosus, a North American crayfish species, is one of the most important aquatic invaders in European inland waters. Despite more than 120 years occurrence in Europe and intense research, there are still gaps in knowledge of its life history and ecology. Investigation into O. limosus invasive success requires identifying the mechanisms that enabled them to establish dense and widespread populations from small initial numbers without observable limitation by an introduction bottleneck. In part, O. limosus success may lie in its ability to reproduce by facultative parthenogenesis. Moreover, there are possible other mating scenarios, because of two mating seasons (autumn and spring) in O. limosus. This work investigated the effect of four reproductive scenarios (autumn mating only, spring mating only, autumn and spring mating, and without mating) on the reproductive success of O. limosus. Females successfully reproduced in all tested mating regimes using parthenogenesis as well as log term sperm storage. This reproductive plasticity likely facilitates the overwhelming success of O. limosus spread and establishment in new localities. It can explain the spread of O. limosus from the initial introduction of 90 specimens to most of continental Europe and Great Britain. These conclusions imply a serious threat, not only for autochthonous European astacofauna, but for other aquatic organisms as well as entire ecosystems. 相似文献
983.
984.
Vladimir L. Semerikov Svetlana A. Semerikova Maria A. Polezhaeva Pavel A. Kosintsev Martin Lascoux 《Molecular ecology》2013,22(19):4958-4971
While many species were confined to southern latitudes during the last glaciations, there has lately been mounting evidence that some of the most cold‐tolerant species were actually able to survive close to the ice sheets. The contribution of these higher latitude outposts to the main recolonization thrust remains, however, untested. In the present study, we use the first range‐wide survey of genetic diversity at cytoplasmic markers in Siberian larch (Larix sibirica; four mitochondrial (mt) DNA loci and five chloroplast (cp) DNA SSR loci) to (i) assess the relative contributions of southern and central areas to the current L. sibirica distribution range; and (ii) date the last major population expansion in both L. sibirica and adjacent Larix species. The geographic distribution of cpDNA variation was uninformative, but that of mitotypes clearly indicates that the southernmost populations, located in Mongolia and the Tien‐Shan and Sayan Mountain ranges, had a very limited contribution to the current populations of the central and northern parts of the range. It also suggests that the contribution of the high latitude cryptic refugia was geographically limited and that most of the current West Siberian Plain larch populations likely originated in the foothills of the Sayan Mountains. Interestingly, the main population expansion detected through Approximate Bayesian Computation (ABC) in all four larch species investigated here pre‐dates the LGM, with a mode in a range of 220 000–1 340 000 years BP. Hence, L. sibirica, like other major conifer species of the boreal forest, was strongly affected by climatic events pre‐dating the Last Glacial Maximum. 相似文献
985.
Telma C. Bernardo Teresa Cunha-Oliveira Teresa L. Serafim Jon Holy Dmytro Krasutsky Oksana Kolomitsyna Pavel Krasutsky António M. Moreno Paulo J. Oliveira 《Bioorganic & medicinal chemistry》2013,21(23):7239-7249
Triterpenoids are a large class of naturally occurring compounds, and some potentially interesting as anticancer agents have been found to target mitochondria. The objective of the present work was to investigate the mechanisms of mitochondrial toxicity induced by novel dimethylaminopyridine (DMAP) derivatives of pentacyclic triterpenes, which were previously shown to inhibit the growth of melanoma cells in vitro. MCF-7, Hs 578T and BJ cell lines, as well as isolated hepatic mitochondria, were used to investigate direct mitochondrial effects. On isolated mitochondrial hepatic fractions, respiratory parameters, mitochondrial transmembrane electric potential, induction of the mitochondrial permeability transition (MPT) pore and ion transport-dependent osmotic swelling were measured. Our results indicate that the DMAP triterpenoid derivatives lead to fragmentation and depolarization of the mitochondrial network in situ, and to inhibition of uncoupled respiration, induction of the permeability transition pore and depolarization of isolated hepatic mitochondria. The results show that mitochondrial toxicity is an important component of the biological interaction of DMAP derivatives, which can explain the effects observed in cancer cells. 相似文献
986.
Andrei A. Krysko Georgiy V. Samoylenko Pavel G. Polishchuk Marina S. Fonari Victor Ch. Kravtsov Sergei A. Andronati Tatyana A. Kabanova Janusz Lipkowski Tetiana M. Khristova Victor E. Kuz’min Vladimir M. Kabanov Olga L. Krysko Alexandre A. Varnek 《Bioorganic & medicinal chemistry》2013,21(15):4646-4661
A series of novel RGD mimetics containing phthalimidine fragment was designed and synthesized. Their antiaggregative activity determined by Born’s method was shown to be due to inhibition of fibrinogen binding to αIIbβ3. Molecular docking of RGD mimetics to αIIbβ3 receptor showed the key interactions in this complex, and also some correlations have been observed between values of biological activity and docking scores. The single crystal X-ray data were obtained for five mimetics. 相似文献
987.
Cemal Kprülüolu Milan Dejmek Michal la Haresh Ajani Hubert Hebabecký Jindich Fanfrlík Radek Jorda Martin Dra
ínský Elika Prochzkov Pavel cha Vladimír Krytof Pavel Hobza Martin Lepík Radim Nencka 《Journal of molecular recognition : JMR》2020,33(8)
We report on the discovery of norbornyl moiety as a novel structural motif for cyclin‐dependent kinase 2 (CDK2) inhibitors which was identified by screening a carbocyclic nucleoside analogue library. Three micromolar hits were expanded by the use of medicinal chemistry methods into a series of 16 novel compounds. They had prevailingly micromolar activities against CDK2 and the best compound of the series attained IC50 of 190 nM. The binding modes were explored in molecular details by modeling and docking. Quantum mechanics‐based scoring was used to rationalize the affinities. In conclusion, the discovered 9‐hydroxymethylnorbornyl moiety was shown by joint experimental‐theoretical efforts to be able to serve as a novel substituent for CDK2 inhibitors. This finding opens door to the exploration of chemical space towards more effective derivatives targeting this important class of protein kinases. 相似文献
988.
Thomas C. Terwilliger Paul D. Adams Pavel V. Afonine Oleg V. Sobolev 《Protein science : a publication of the Protein Society》2020,29(1):87-99
A procedure for building protein chains into maps produced by single‐particle electron cryo‐microscopy (cryo‐EM) is described. The procedure is similar to the way an experienced structural biologist might analyze a map, focusing first on secondary structure elements such as helices and sheets, then varying the contour level to identify connections between these elements. Since the high density in a map typically follows the main‐chain of the protein, the main‐chain connection between secondary structure elements can often be identified as the unbranched path between them with the highest minimum value along the path. This chain‐tracing procedure is then combined with finding side‐chain positions based on the presence of density extending away from the main path of the chain, allowing generation of a Cα model. The Cα model is converted to an all‐atom model and is refined against the map. We show that this procedure is as effective as other existing methods for interpretation of cryo‐EM maps and that it is considerably faster and produces models with fewer chain breaks than our previous methods that were based on approaches developed for crystallographic maps. 相似文献
989.
Petr Pyek Jan uda Petr milauer Hana Sklov Zuzana Chumov Carla Lambertini Magdalena Lu
anov Hana Ryav Pavel Trvní
ek Kristýna emberov Laura A. Meyerson 《Ecology and evolution》2020,10(3):1106-1118
Among the traits whose relevance for plant invasions has recently been suggested are genome size (the amount of nuclear DNA) and ploidy level. So far, research on the role of genome size in invasiveness has been mostly based on indirect evidence by comparing species with different genome sizes, but how karyological traits influence competition at the intraspecific level remains unknown. We addressed these questions in a common‐garden experiment evaluating the outcome of direct intraspecific competition among 20 populations of Phragmites australis, represented by clones collected in North America and Europe, and differing in their status (native and invasive), genome size (small and large), and ploidy levels (tetraploid, hexaploid, or octoploid). Each clone was planted in competition with one of the others in all possible combinations with three replicates in 45‐L pots. Upon harvest, the identity of 21 shoots sampled per pot was revealed by flow cytometry and DNA analysis. Differences in performance were examined using relative proportions of shoots of each clone, ratios of their aboveground biomass, and relative yield total (RYT). The performance of the clones in competition primarily depended on the clone status (native vs. invasive). Measured in terms of shoot number or aboveground biomass, the strongest signal observed was that North American native clones always lost in competition to the other two groups. In addition, North American native clones were suppressed by European natives to a similar degree as by North American invasives. North American invasive clones had the largest average shoot biomass, but only by a limited, nonsignificant difference due to genome size. There was no effect of ploidy on competition. Since the North American invaders of European origin are able to outcompete the native North American clones, we suggest that their high competitiveness acts as an important driver in the early stages of their invasion. 相似文献
990.