Numerical Study of the Dynamics of an Electron Avalanche in the Forming Cathode Sheath of a Self-Sustained Volume Discharge

Plasma Physics Reports - The dynamics of an electron avalanche starting from the flat cathode surface and from the tops of microtips of different heights on the cathode surface is compared. The...     

Gain-of-function hot spot mutant p53R248Q regulation of integrin/FAK/ERK signaling in esophageal squamous cell carcinoma

PurposeTP53, encoding the protein p53, is among the most frequently mutated genes in all cancers. A high frequency of 60 – 90% mutations is seen in esophageal squamous cell carcinoma (ESCC) patients. Certain p53 mutants show gain-of-function (GoF) oncogenic features unrelated to its wild type functions.MethodsThis study functionally characterized a panel of p53 mutants in individual ESCC cell lines and assayed for GoF oncogenic properties.ResultsThe ESCC cell line with endogenous p53^R248Q expression showed suppressed tumor growth in an immunocompromised mouse model and suppressed colony growth in in vitro three-dimensional culture, when depleted of the endogenous p53 protein expression. This suppression is accompanied by suppressed cell cycle progression, along with reduced integrin expression and decreased focal adhesion kinase and extracellular-regulated protein kinase signaling and can be compensated by expression of a constitutively active mitogen-activated protein. P53^R248Q enhances cell proliferation upon glutamine deprivation, as compared to other non-GoF mutants.ConclusionsIn summary, study of the functional contributions of endogenous p53 mutants identified a novel GoF mechanism through which a specific p53 mutant exerts oncogenic features and contributes to ESCC tumorigenesis.     

An efficient pipeline for ancient DNA mapping and recovery of endogenous ancient DNA from whole‐genome sequencing data

Ancient DNA research has developed rapidly over the past few decades due to improvements in PCR and next‐generation sequencing (NGS) technologies, but challenges still exist. One major challenge in relation to ancient DNA research is to recover genuine endogenous ancient DNA sequences from raw sequencing data. This is often difficult due to degradation of ancient DNA and high levels of contamination, especially homologous contamination that has extremely similar genetic background with that of the real ancient DNA. In this study, we collected whole‐genome sequencing (WGS) data from 6 ancient samples to compare different mapping algorithms. To further explore more effective methods to separate endogenous DNA from homologous contaminations, we attempted to recover reads based on ancient DNA specific characteristics of deamination, depurination, and DNA fragmentation with different parameters. We propose a quick and improved pipeline for separating endogenous ancient DNA while simultaneously decreasing homologous contaminations to very low proportions. Our goal in this research was to develop useful recommendations for ancient DNA mapping and for separation of endogenous DNA to facilitate future studies of ancient DNA.     

Results of testing the comparatory method: The curvature of the shell valve frontal section is inappropriate as a systematic character for the freshwater pearl mussel of the genus Margaritifera

This paper continues a discussion on the number of pearl mussel species of the genus Margaritifera in northern Europe. A biometric study of 1711 pearl mussel Margaritifera margaritifera shells from 15 rivers in Russia and Latvia (basins of the White and Baltic seas) has been conducted. All the examined samples fall into two groups: the northern group (with the shells more flattened on average, f. margaritifera) and the southern one (with more convex shells, f. elongata); the boundary between these groups is at 63° N. Analysis of intrapopulation variation has shown that the samples contain individuals that correspond to f. margaritifera, f. elongata, and f. borealis. However, any hiatus between these forms is absent in all the samples, and individuals belonging to two intermediate forms are rather frequent. The hypothesis on the species specificity of the shell valve frontal section has not been confirmed based on examination of large shell samples. The pearl mussels inhabiting rivers of Northern Europe belong to a single species, M. margaritifera.     

Mechanism of density compensation in island bumblebee assemblages (Hymenoptera, Apidae, Bombus) and the notion of reserve compensatory species

The notion of a dynamic compensatory system is discussed, characterized by the alternation of species occupying the leading position in bumblebee assemblages, while the total density of these pollinators in island ecosystems remains at similar levels. The functioning of the compensatory system is regulated by both abiotic factors (the weather and climate) and biotic factors (competition for trophic resources). The stability of the system is determined by the presence of reserve compensatory species capable of rapid population growth against the background of depressed abundance of other species under changing environmental conditions.     

Genetic differentiation of sockeye salmon Oncorhynchus nerka (Walbaum, 1792) populations of eastern Kamchatka

The interpopulation differentiation of the sockeye salmon Oncorhynchus nerka (Walbaum) from the Olyutorskiy and Karaginskiy districts and from the Kamchatka River basin was examined based on the allelic variation at eight microsatellite loci (Ots107, Oki1a, Oki1b, One104, One109, OtsG68, OtsG85, and Oki6). The genetic diversity of samples from the northern rivers was lower, compared to samples from the Kamchatka River basin. Significant heterogeneity was found in the allele-frequency distribution at microsatellite loci of sockeye salmon from the investigated localities. The degree of genetic similarity of populations corresponded to their geographic closeness. The differences between population groups greatly exceeded the level of interpopulation differentiation. The analyzed samples formed four relatively separate groups: Lake Azabachye, Kamchatka River basin, Karaginskiy area (including the Navyrinvayam River in the south of the Olyutorskiy district), and northern Olyutorskiy area. The identification likelihood estimates of eastern Kamchatkan sockeye salmon in mixed aggregations at the level of population groups were fairly high (67.2–81.8%), greatly exceeding the accuracy of identification of individual populations.