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961.
Katarzyna Parys Nicholas R. Colaianni Ho-Seok Lee Ulrich Hohmann Natalie Edelbacher Alen Trgovcevic Zuzana Blahovska Duhwa Lee Alexander Mechtler Zsuzsanna Muhari-Portik Mathias Madalinski Niklas Schandry Isaac Rodríguez-Arévalo Claude Becker Elisabeth Sonnleitner Arthur Korte Udo Bläsi Niko Geldner Youssef Belkhadir 《Cell host & microbe》2021,29(4):620-634.e9
962.
Genetic microdifferentiation has been studied among four endogamous villages of the Bystrica Valley in the Kysuce region of northwest Slovakia, which arose from a single ancestral population about 15 generations ago. Genetic distances and sample kinship between the villages were estimated from the gene frequencies of seven serum-group and isozyme genetic markers. The genetic distance was found to correlate positively (though insignificantly) with the geographic distance, and negatively with the intensity of migration between villages; the sample kinship correlates negatively with geography as well as with the genetic distance. This pattern of genetic structure within the area indicates that the genetic variation among the villages is attributable to the genetic drift. Thus, drift has brought about a detectable differentiation in the area within a limited period of approximately 300 years, in spite of the fact that the villages were not completely genetically isolated from each other. The finding of a negative correlation between the sample kinship and geographic distance indicates that the recent breakdown of genetic isolates in Slovakia is likely to be accompanied with an overall increase of heterozygosity. 相似文献
963.
964.
Large scale windstorms disturbed forest ecosystems in the Tatra Mountains in 2004, and were followed by a severe fire in 2005.
A long-term study on the vegetation successional dynamics of the area was launched immediately after the 2005 event. Relevé
plots were established under five different disturbance and management treatments: windthrow left, windthrow removed, hydrologically
managed, burnt and reference. We used weighted Ellenberg’s indicator plant values for ordination analyses of the following
environmental gradients: light, temperature, continentality, moisture, acidity, nitrogen. Successional patterns depended on
the management treatment. Heavily burnt areas were colonized by plants disseminated by airborn diasporas, mainly by Chamaerion angustifolium, less burnt or unburnt localities were settled by plants germinating from the soil seed bank or by plants surviving by root
system. Nitrophilous weed vegetation invaded plots with increased moisture (fallen or standing overstory vegetation or irrigated
by man-made system) and nitrogen (burnt or windthrow removal). The felled-area species were recorded in each plot. Abundant
natural regeneration was observed in plots with increased moisture. The moss layer disappeared soon after the disturbance
events. The results presented here refer to a very early successional stage, new insights into initial successional paterns
are gained. 相似文献
965.
Zuzana Münzbergová Věra Hadincová Jan Wild Tomáš Herben Jana Marešová 《Biological invasions》2010,12(8):2471-2486
Understanding dispersal ability of an invasive species is crucial for describing its potential spread. Despite this, we still
know little about the dispersal potential of many invasive species. We explored dispersal spectra in Pinus strobus, an invasive tree in sandstone areas in Central Europe. We studied dispersal of the species using distribution of self-sown
trees in the field. We compared these observed data with theoretical dispersal curves derived using information on wind speed,
seed terminal velocity and tree height. Finally, we fitted various empirical dispersal curves to the observed data. All the
analyses based on the observed field data were done for the whole dataset, and for the dataset divided by habitat types and
age categories of the self-sown trees. P. strobus seeds can disperse up to 757.5 m from the source. The observed data fall within the confidence intervals of the predictions
based on a negative exponential model. When comparing different dispersal functions fitted to the data, it was not easy to
decide which of the dispersal curves provides the overall best fit. This was because different functions were the best predictors
of different parts of the dispersal curve. We suggest that future studies should provide not only empirical fitted dispersal
curves but also observed data and provide estimates of confidence intervals. Such information will provide insights into the
reliability of the dispersal estimates in general and help to evaluate the predictive power of the different models. 相似文献
966.
Jana Christophoryová Zuzana Krumpálová Ján Krištofík Zlatica Országhová 《Biologia》2011,66(4):669-677
The hypothesis of associating pseudoscorpions with bird nest types was tested on the basis of an analysis of 480 specimens.
Eleven pseudoscorpion species were found in 171 nests of 28 different bird species collected in Slovakia, Austria and the
Czech Republic. The frequent appearance of Cheiridium museorum, Dactylochelifer latreillii, Chernes hahnii, Dendrochernes cyrneus and Allochernes wideri was confirmed. High proportion and association of Pselaphochernes scorpioides in hoopoe hollow nests with decomposed substrate, D. cyrneus in the Eurasian tree sparrow nest boxes and A. wideri in the nests of the tawny owls, the European scops owls and the European roller was proved. In contrast, C. hahnii and D. latreillii were related to the nest fauna of blackbirds and song thrushes, C. museorum to the nests of white wagtails situated on the ground and on buildings and C. cancroides to the nests in synanthropic habitats. Until present, the occurrence of 22 pseudoscorpion species has been confirmed in the
bird nests of Central Europe based on the obtained results and published resources. According to the association to bird nests
these pseudoscorpions were classified as (1) nidixenous species — Chthonius fuscimanus, C. tetrachelatus, Mundochthonius styriacus, Neobisium carcinoides, N. crassifemoratum, N. inaequale,
N. sylvaticum, Chernes cimicoides, C. similis, C. vicinus, Allochernes powelli, Lamprochernes chyzeri, L. nodosus and Larca lata; and (2) nidiphilous species — C. museorum, C. cancroides, A. wideri, D. cyrneus, D. latreillii, C. hahnii, D. panzeri and P. scorpioides. 相似文献
967.
Zuzana Saidak Cedric Boudot Laurent Petit Romuald Mentaverri 《Experimental cell research》2009,315(12):2072-40933
Breast cancer is the most frequent form of cancer in women, with the highest incidence of metastasis to the bone. The reason for the preferential destination to the bone is believed to be due to chemoattractant factors released during bone resorption, which act on the cancer cells facilitating their metastasis. One of the factors released during osteolysis that may mediate breast cancer bone localization is Ca2+. Here, we show that extracellular Ca2+ (Ca2+o) acting via the calcium-sensing receptor (CaSR), greatly promotes the migration of bone-preferring breast cancer cells. In Boyden Chamber and Scratch Wound migration assays, an increase in breast cancer cell migration was observed at 2.5 mM and 5 mM Ca2+o compared to basal levels for three of the four breast cancer cell lines tested. However, a significantly greater migratory response was observed for the highly bone metastatic MDA-MB-231 cells, compared to the MCF7 and T47D, which have a lower metastatic potential in vivo. The BT474 cells, which do not metastasize to the bone, did not respond to elevated concentrations of Ca2+o in the migration assays. Inhibition of either ERK1/2 MAPK or phospholipase Cβ (PLCβ) led to an abolition of the Ca2+o-induced migration, implicating these pathways in the migratory response. Knockdown of the CaSR by siRNA resulted in an inhibition of the Ca2+o-induced migration, demonstrating the involvement of this receptor in the effect. These results suggest that the activation of the CaSR by elevated Ca2+o concentrations, such as those found near resorbing bone, produces an especially strong chemoattractant effect on bone metastatic breast cancer cells toward the Ca2+-rich environment. 相似文献
968.
Zuzana Jasencakova Anja Groth 《BioEssays : news and reviews in molecular, cellular and developmental biology》2010,32(10):847-855
Cancer cells accumulate widespread local and global chromatin changes and the source of this instability remains a key question. Here we hypothesize that chromatin alterations including unscheduled silencing can arise as a consequence of perturbed histone dynamics in response to replication stress. Chromatin organization is transiently disrupted during DNA replication and maintenance of epigenetic information thus relies on faithful restoration of chromatin on the new daughter strands. Acute replication stress challenges proper chromatin restoration by deregulating histone H3 lysine 9 mono‐methylation on new histones and impairing parental histone recycling. This could facilitate stochastic epigenetic silencing by laying down repressive histone marks at sites of fork stalling. Deregulation of replication in response to oncogenes and other tumor‐promoting insults is recognized as a significant source of genome instability in cancer. We propose that replication stress not only presents a threat to genome stability, but also jeopardizes chromatin integrity and increases epigenetic plasticity during tumorigenesis. 相似文献
969.
Elicitins are low-molecular-weight proteins representing the elicitor family secreted by many species of the oomycete Phytophthora. Elicitins induce a hypersensitive reaction in tobacco, a process that is triggered by binding of elicitin to the high-affinity site on the plasma membrane. Specific interaction of cryptogein with the binding sites on tobacco plasma membranes was studied using the piezoelectric biosensor in real time in a flow-through mode. Cryptogeins (wild-type and mutant forms) were covalently immobilized on the sensing surface, and membrane vesicles containing receptors were in solution. Kinetic characterization of the interaction provided values of kinetic rate association (ka) = 5.74 · 106 M1 s−1 and kinetic rate dissociation (kd) = 6.87 10−4 s−1 constants, respectively. The kinetic equilibrium dissociation constant was calculated as KD = 12.0 nM. The piezoelectric biosensor appeared to be a convenient tool for studying interactions of receptors embedded in membrane vesicles. 相似文献
970.
Recent studies in mice have provided strong evidence for a modifier gene that is capable of effecting the expression of the
mouse equivalent of familial adenomatous polyposis (FAP). A candidate gene has been proposed, namely secretory phospholipase
A2 (sPLA2). Increased tumor number in mice was correlated with low levels of sPLA2 expression and the presence of truncating mutations within the sPLA2 gene. In an attempt to determine whether any genetic alterations in the sPLA2 gene were associated with the expression of FAP in man, we investigated the genetic structure of sPLA2 in 97 polyposis coli patients presenting with various disease phenotypes, and its expression in 8 FAP patients displaying
markedly different disease characteristics. In the current study no inactivating mutations in the sPLA2 gene were identified, suggesting that human sPLA2 is not associated with phenotypic variation in FAP.
Received: 25 March 1996 / Revised: 9 April 1996 相似文献