[1] High resolution measurements of plasma in the plasma sheets of Mars and Venus performed by almost identical plasma instruments ASPERA-3 on the Mars Express spacecraft and ASPERA-4 on Venus Express reveal similar features of bursty fluxes of escaping planetary ions. A period of bursts lasts about 1-2 min. Simultaneous magnetic field measurements on Venus Express show that these burst-like features arise due to flapping motions of the plasma sheet. Their occurrence can be related to large-amplitude waves propagating on the plasma sheet surface and launched by reconnection in the magnetic tails. Citation:
BackgroundSpider silks are spectacular examples of phenotypic diversity arising from adaptive molecular evolution. An individual spider can produce an array of specialized silks, with the majority of constituent silk proteins encoded by members of the spidroin gene family. Spidroins are dominated by tandem repeats flanked by short, non-repetitive N- and C-terminal coding regions. The remarkable mechanical properties of spider silks have been largely attributed to the repeat sequences. However, the molecular evolutionary processes acting on spidroin terminal and repetitive regions remain unclear due to a paucity of complete gene sequences and sampling of genetic variation among individuals. To better understand spider silk evolution, we characterize a complete aciniform spidroin gene from an Argiope orb-weaving spider and survey aciniform gene fragments from congeneric individuals.ResultsWe present the complete aciniform spidroin (AcSp1) gene from the silver garden spider Argiope argentata (Aar_AcSp1), and document multiple AcSp1 loci in individual genomes of A. argentata and the congeneric A. trifasciata and A. aurantia. We find that Aar_AcSp1 repeats have >98% pairwise nucleotide identity. By comparing AcSp1 repeat amino acid sequences between Argiope species and with other genera, we identify regions of conservation over vast amounts of evolutionary time. Through a PCR survey of individual A. argentata, A. trifasciata, and A. aurantia genomes, we ascertain that AcSp1 repeats show limited variation between species whereas terminal regions are more divergent. We also find that average dN/dS across codons in the N-terminal, repetitive, and C-terminal encoding regions indicate purifying selection that is strongest in the N-terminal region.ConclusionsUsing the complete A. argentata AcSp1 gene and spidroin genetic variation between individuals, this study clarifies some of the molecular evolutionary processes underlying the spectacular mechanical attributes of aciniform silk. It is likely that intragenic concerted evolution and functional constraints on A. argentata AcSp1 repeats result in extreme repeat homogeneity. The maintenance of multiple AcSp1 encoding loci in Argiope genomes supports the hypothesis that Argiope spiders require rapid and efficient protein production to support their prolific use of aciniform silk for prey-wrapping and web-decorating. In addition, multiple gene copies may represent the early stages of spidroin diversification.
Laser induced breakdown spectroscopy(LIBS) technique coupled with support vector machine(SVM) and partial least square(PLS) methods was proposed to perform quantitative and classification analysis of 20 slag samples. The characteristic line (Ca, Si, Al, Mg and Ti) of LIBS spectra for slag samples can be 10 identified based on NIST database. At first, quantitative analysis of the major components(Fe2O3, CaO, SiO2, Al2O3, MgO and TiO2) in slag samples was completed by SVM with the full spectra as input variable, and two parameters(kernel parameter of RBF-γ and σ 2 ) of SVM were optimized by grid search(GS) approach based on 5-fold cross-validation(CV). The performance of SVM calibration model was investigated by 5-fold CV, the prediction accuracy and root mean square error(RMSE) of SVM and 15 PLS were employed to validate the predictive ability of multivariate SVM calibration model in slag. SVM model can eliminate the influence of nonlinear factors due to self-absorption in the plasma and provide a better predictive result. And then, two type of slag samples(open-hearth furnace slag and high titanium slag) were identified and classified by partial least squares-discrimination analysis(PLS-DA) method with different input variables, sensitivity, specificity and accuracy were calculated to evaluate the classification 20 performance of PLS-DA model for slag samples. It has been confirms that LIBS technique coupled with SVM and PLS methods is promising approach to achieve the online analysis and process control of slag and even metallurgy field.
Di-(2-ethylhexyl) phthalate (DEHP) is a plasticizer used in the polyvinyl chloride industry worldwide. DEHP exists in the aquatic environments for decades. However, the toxicological effects of DEHP to aquatic organisms have not been adequately researched. We investigated acute toxicity, oxidative damage, antioxidant enzyme activities, and gene expression patterns of antioxidant enzymes in juvenile and adult Daphnia magna exposed to DEHP. We found that the median lethal concentrations (LC) of DEHP for juveniles exposed for 24 and 48 h were 0.83 and 0.56 mg L, respectively. The LC of DEHP in adults exposed for 24 and 48 h were 0.48 and 0.35 mg L. Daphnia magna that was exposed to DEHP had increased malondialdehyde levels for 24 h and lower total antioxidant capacity compared with the control. Activity levels of antioxidant enzymes superoxide dismutase and phase II detoxifying enzyme glutathione S-transferases were significantly higher upon initial exposure for 24 h, and enzyme activity was then diminished at high concentrations and prolonged exposure for 48 h. Gene expression levels of cat and gst were notably reduced or increased upon DEHP exposure. These findings suggest that DEHP can cause biochemical and physiological effects in juvenile and adult D. magna by inhibiting enzymes, an increase in lipid peroxidation levels and changes both transcription levels of enzymes (cat, gst). On the whole, juveniles and adults both responded similarly to DEHP. Our findings will contribute to the understanding of toxic mechanisms in phthalate esters and the evaluation of environmental risks in aquatic ecosystems.
Natural triploid and asexually reproducing clonal diploid loaches are found in Japanese populations of the loach, Misgurnus anguillicaudatus. The distribution of polyploid loaches in Chinese populations has not been studied except for a few cytogenetic studies that described the occurrence of polyploidy. In the present study, we examined the ploidy status of a total of 762 specimens collected from 29 localities in China by measurements of erythrocytic cell nucleus after the ploidy determination performed by chromosome counting and DNA content ‰ow-cytometry in selected individuals. Among diploid, triploid and tetraploid individuals, signiˆcant diŠerences were detected in major and minor diameters of nucleus, and also nuclear volume. A few triploid (3n) loaches were detected in relatively wide areas including Hohhot, Neimenggu (3.3), Tianjin (5.3), Hangzhou, Zhejiang
An internal reference-external standard with iteration correction (IRESIC) method is proposed to correct for the self-absorption effect and plasma temperature in CF-LIBS based on an internal reference line and one standard sample.
Sebacinoid fungi show a broad mycorrhizal capacity; therefore, they play a very important role in natural systems. Worldwide, fungi of Sebacinales are present under different environmental conditions and associate with diverse plant hosts, however, are hitherto poorly studied in China. Two sebacinoid ectomycorrhizae (ECM), Pinirhiza multifurcata and Pinirhiza nondextrinoidea, are described in detail morphologically and anatomically in the present study. They share a plectenchymatous outer mantle with multiply ramified hyphae in a gelatinous matrix, clampless, thin, thick-walled emanating hyphae with mostly Y-shaped ramifications and triangular inflations at the point of ramification. P. multifurcata and P. nondextrinoidea can be distinguished by thick cells in mantle layers, the ramification of emanating hyphae, the presence or absence of rhizomorphs, as well as the differing color reaction in Melzer's reagent. The putative molecular phylogenetic relationships of P. multifurcata and P. nondextrinoidea were inferred by analyses of the partial large subunit nuclear rDNA (nLSU); however, an affiliation to fungal species was not possible. This is the first report of sebacinoid ECM on Chinese pine.
Dibutyl phthalate (DBP) poses a severe threat to aquatic ecosystems, introducing hazards to both aquatic species and human health. The ecotoxic effects of DBP on aquatic organisms have not been fully investigated. This study investigates acute toxicity, oxidative damage, and antioxidant enzyme parameters in neonate and adult Daphnia magna exposed to DBP. The obtained results show comparable DBP toxic responses in neonates and adults. The median lethal concentrations (LC50) of DBP in neonates exposed for 24 and 48 h were 3.48 and 2.83 mg/L, respectively. The LC50 of adults for the same DBP exposure durations were 4.92 and 4.31 mg/L, respectively. Increased hydrogen peroxide and malondialdehyde were found in neonates and adults at both 24 and 48 h, while the total antioxidant capacity decreased. Superoxide dismutase activity increased significantly in neonates and adults exposed to 0.5 mg/L DBP, and subsequently diminished at higher DBP concentrations and prolonged exposure. Catalase and glutathione S-transferases activities both decreased markedly in neonates and adults. The changes observed were found to be time and concentration dependent. Overall, these data indicated that the acute toxic effects of DBP exposure on neonates were more pronounced than in adults, and oxidative injury may be the main mechanism of DBP toxicity. These results provide a functional link for lipid peroxidation, antioxidant capacity, and antioxidant enzyme levels in the Daphnia magna response to DBP exposure.
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