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Here we report a facile switchable fluorescent QD probe for F−ions, which is based on the hydrogen bonding-driven aggregation and the analyte-triggered disaggregation. [ABSTRACT FROM AUTHOR]

This communication describes a facile and mild chemical etching method for resizing of CdTe nanocrystals, which provides a possible approach for tailoring the size-dependent properties of the nanocrystals. [ABSTRACT FROM AUTHOR]

The vacuum ultraviolet (VUV) pulsed field ionization-photoelectron (PFI-PE) spectra for CO[sub 2] have been measured in the energy range of 17.2-19.0 eV, showing complex vibronic structures for the CO[sub 2][sup +](A [sup 2]Π[sub u] and B [sup 2]Σ[sub u][sup +]) states. The PFI-PE spectra for CO[sub 2][sup +](A [sup 2]Π[sub u] and B [sup 2]Σ[sub u][sup +]) are dominated by the v[sub 1][sup +] (symmetric stretching) vibrational progressions, and weak bands due to excitation of both even and odd quanta of the v[sub 2][sup +] (bending) and v[sub 3][sup +] (antisymmetric stretching) modes are observed in the VUV-PFI-PE spectra. The simulation of rotational contours resolved in the PFI-PE vibronic bands associated with excitation to CO[sub 2][sup +](A [sup 2]Π[sub 3/2,1/2u];v[sub 1][sup +]=0-5,v[sub 2][sup +]=0,v[sub 3][sup +]=0) and CO[sub 2][sup +](B [sup 2]Σ[sub u][sup +];0,0,0) has yielded accurate ionization energies for the formation of these states from CO[sub 2](X [sup 1]Σ[sub g][sup +]). Three-dimensional potential energy functions (PEFs) for CO[sub 2][sup +](B [sup 2]Σ[sub u][sup +]) have also been generated theoretically using the complete active space self-consistent field and internally contracted multireference configuration interaction methods. Based on these PEFs, vibrational energy levels for CO[sub 2][sup +](B [sup 2]Σ[sub u][sup +]), together with the Franck-Condon factors for their formation from CO[sub 2](X [sup 1]Σ[sub g][sup +]), have been calculated. With the guide of these theoretical predictions, the vibrational bands resolved in the PFI-PE spectrum for CO[sub 2][sup +](B [sup 2]Σ[sub u][sup +]) have been satisfactorily assigned. This assignment reveals the nature of many vibrational PFI-PE bands as originated from anharmonic resonance interactions and members of Fermi polyads. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The vacuum ultraviolet pulsed field ionization-photoelectron (PFI-PE) spectra for CO[sub 2] have been measured in the energy range of 13.6-14.7 eV, revealing complex vibronic structures for the ground CO[sub 2][sup +](X [sup 2]Π[sub g]) state. Many vibronic bands for CO[sub 2][sup +](X [sup 2]Π[sub g]), which were not resolved in previous photoelectron studies, are identified in the present measurement based on comparison with available optical data and theoretical predictions. As observed in the HeI photoelectron spectrum of CO[sub 2], the PFI-PE spectrum is dominated by the symmetry allowed ν[sub 1][sup +] (symmetric stretch) vibrational progression for CO[sub 2][sup +](X [sup 2]Π[sub g]). However, PFI-PE vibronic bands due to excitation of the symmetry disallowed ν[sub 2][sup +] (bending) and ν[sub 3][sup +] (asymmetric stretch) modes with both odd quanta, together with the symmetry allowed even quanta excitations, are clearly discernible. The simulation of rotational contours resolved in PFI-PE vibronic bands associated with excitation to the (ν[sub 1][sup +]=0-1, ν[sub 2][sup +]=0-2, ν[sub 3][sup +]=0) vibrational levels has yielded accurate ionization energies for the formation of these vibronic states from CO[sub 2](X [sup 1]Σ[sub g][sup +]). © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Multidrug resistance (MDR) is a major factor in the failure of many forms of tumor chemotherapy. Development of a specific ligand for MDR-reversal would enhance the intracellular accumulation of therapeutic agents and effectively improve the tumor treatments. Here, an aptamer was screened against a doxorubicin (DOX)-resistant human hepatocellular carcinoma cell line (HepG2/DOX) via cell-based systematic evolution of ligands by exponential enrichment. A 50 nt truncated sequence termed d3 was obtained with high affinity and specificity for HepG2/DOX cells. Multidrug resistance protein 1 (MDR1) is determined to be a possible recognition target of the selected aptamer. Aptamer d3 binding was revealed to block the MDR of the tumor cells and increase the accumulation of intracellular anticancer drugs, including DOX, vincristine, and paclitaxel, which led to a boost to the cell killing of the anticancer drugs and lowering their survival of the tumor cells. The aptamer d3-mediated MDR-reversal for effective chemotherapy was further verified in an in vivo animal model, and combination of aptamer d3 with DOX significantly improved the suppression of tumor growth by treating a xenograft HepG2/DOX tumor in vivo. This work demonstrates the feasibility of a therapeutic DNA aptamer as a tumor MDR-reversal agent, and combination of the selected aptamer with chemotherapeutic drugs shows great potential for liver cancer treatments. [ABSTRACT FROM AUTHOR]

Phenols were a kind of pollutant in coal chemical wastewater with high concentration and difficult to decompose and have a significant impact on the subsequent biochemical treatment of the wastewater. In addition, phenols were a kind of weak electrolytes that partially dissociation oxidation under weakly alkaline conditions, making recovery more difficult. In order to solve this problem, phenols were extracted from weak alkaline wastewater with a synergistic solvent. First, the interaction between solvents and phenols and the solvent effect of solvents were calculated by quantum chemistry and the synergistic extractant cyclohexanone/1-pentanol was determined to have significant advantages. Moreover, the synergistic extractant was further analyzed through independent gradient model based on Hirshfeld partition analysis, atoms in molecule topology analysis, electrostatic potential analysis. Results indicated that the synergistic extract can provide multiple hydrogen bond interactions with phenol due to the double action sites of the C=O group of ketone and the -OH group of alcohol. In addition, the efficacy of the extractant was validated by multistage extraction, indicating partial dissociation oxidation of hydroquinone to benzoquinone under weakly alkaline conditions, with removal rates of 99.5% and 99.2% for phenol and hydroquinone, respectively. In general, the synergistic extractant can effectively remove phenols. [ABSTRACT FROM AUTHOR]

Interior tomography is clinically desired to reduce the radiation dose rendered to patients. In this work, a new statistical interior tomography approach for computed tomography is proposed. The developed design focuses on taking into account the statistical nature of local projection data and recovering fine structures which are lost in the conventional total-variation (TV)—minimization reconstruction. The proposed method falls within the compressed sensing framework of TV minimization, which only assumes that the interior ROI is piecewise constant or polynomial and does not need any additional prior knowledge. To integrate the statistical distribution property of projection data, the objective function is built under the criteria of penalized weighed least-square (PWLS-TV). In the implementation of the proposed method, the interior projection extrapolation based FBP reconstruction is first used as the initial guess to mitigate truncation artifacts and also provide an extended field-of-view. Moreover, an interior feature refinement step, as an important processing operation is performed after each iteration of PWLS-TV to recover the desired structure information which is lost during the TV minimization. Here, a feature descriptor is specifically designed and employed to distinguish structure from noise and noise-like artifacts. A modified steepest descent algorithm is adopted to minimize the associated objective function. The proposed method is applied to both digital phantom and in vivo Micro-CT datasets, and compared to FBP, ART-TV and PWLS-TV. The reconstruction results demonstrate that the proposed method performs better than other conventional methods in suppressing noise, reducing truncated and streak artifacts, and preserving features. The proposed approach demonstrates its potential usefulness for feature preservation of interior tomography under truncated projection measurements. [ABSTRACT FROM AUTHOR]

Accelerating MR scan is of great significance for clinical, research and advanced applications, and one main effort to achieve this is the utilization of compressed sensing (CS) theory. Nevertheless, the existing CSMRI approaches still have limitations such as fine structure loss or high computational complexity. This paper proposes a novel iterative feature refinement (IFR) module for accurate MR image reconstruction from undersampled K-space data. Integrating IFR with CSMRI which is equipped with fixed transforms, we develop an IFR-CS method to restore meaningful structures and details that are originally discarded without introducing too much additional complexity. Specifically, the proposed IFR-CS is realized with three iterative steps, namely sparsity-promoting denoising, feature refinement and Tikhonov regularization. Experimental results on both simulated and in vivo MR datasets have shown that the proposed module has a strong capability to capture image details, and that IFR-CS is comparable and even superior to other state-of-the-art reconstruction approaches. [ABSTRACT FROM AUTHOR]

Amino acid-dithiocarbamate (amino acid-DTC) was developed as both the reductant and ligand stabilizer for biomimetic synthesis of gold nanoparticles (AuNPs), which served as an excellent surface-enhanced Raman scattering (SERS) contrast nanoprobe for cell imaging. Glycine (Gly), glutamic acid (Glu), and histidine (His) with different isoelectric points were chosen as representative amino acid candidates to synthesize corresponding amino acid-DTC compounds through mixing with carbon disulfide (CS2), respectively. The pyrogenic decomposition of amino acid-DTC initiated the reduction synthesis of AuNPs, and the strong coordinating dithiocarbamate group of amino acid-DTC served as a stabilizer that grafted onto the surface of the AuNPs, which rendered the as-prepared nanoparticles a negative surface charge and high colloidal stability. MTT cell viability assay demonstrated that the biomimetic AuNPs possessed neglectful toxicity to the human hepatoma cell, which guaranteed them good biocompatibility for biomedical application. Meanwhile, the biomimetic AuNPs showed a strong SERS effect with an enhancement factor of 9.8 × 105 for the sensing of Rhodamine 6G, and two distinct Raman peaks located at 1363 and 1509 cm−1 could be clearly observed in the cell-imaging experiments. Therefore, biomimetic AuNPs can be explored as an excellent SERS contrast nanoprobe for biomedical imaging, and the amino acid-DTC mediated synthesis of the AuNPs has a great potential in bio-engineering and biomedical imaging applications. [ABSTRACT FROM AUTHOR]

Protein labeling for dynamic living cell imaging plays a significant role in basic biological research, as well as in clinical diagnostics and therapeutics. We have developed a novel strategy in which the dynamic visualization of proteins within living cells is achieved by using aptamers as mediators for indirect protein labeling of quantum dots (QDs). With this strategy, the target protein angiogenin was successfully labeled with fluorescent QDs in a minor intactness model, which was mediated by the aptamer AL6-B. Subsequent living cell imaging analyses indicated that the QDs nanoprobes were selectively bound to human umbilical vein endothelial cells, gradually internalized into the cytoplasm, and mostly localized in the lysosome organelle, indicating that the labeled protein retained high activity. Compared with traditional direct protein labeling methods, the proposed aptamer-mediated strategy is simple, inexpensive, and provides a highly selective, stable, and intact labeling platform that has shown great promise for future biomedical labeling and intracellular protein dynamic analyses. [ABSTRACT FROM AUTHOR]

Coronavirus membrane protein is a major component of the viral envelope and plays a central role in the viral life cycle. Studies of the coronavirus membrane protein (M) have mainly focused on its role in viral assembly and budding, but whether M protein is involved in the initial stage of viral replication remains unclear. In this study, eight proteins in transmissible gastroenteritis virus (TGEV)-infected cells coimmunoprecipitated with monoclonal antibodies (MAb) against M protein in PK-15 cells, heat shock cognate protein 70 (HSC70), and clathrin were identified by matrix-assisted laser desorption ionization-tandem time of flight mass spectrometry (MALDI-TOF MS). Further studies demonstrated that HSC70 and TGEV M colocalized on the cell surface in early stages of TGEV infection; specifically, HSC70 bound M protein through its substratebinding domain (SBD) and preincubation of TGEV with anti-M serum to block the interaction of M and HSC70 reduced the internalization of TGEV, thus demonstrating that the M-HSC70 interaction mediates the internalization of TGEV. Remarkably, the process of internalization was dependent on clathrin-mediated endocytosis (CME) in PK-15 cells. Furthermore, inhibition of the ATPase activity of HSC70 reduced the efficiency of CME. Collectively, our results indicated that HSC70 is a newly identified host factor involved in TGEV infection. Taken together, our findings clearly illustrate a novel role for TGEV M protein in the viral life cycle and present a unique strategy used by HSC70 to promote TGEV infection in which the interaction with M protein directs viral internalization. These studies provide new insights into the life cycle of coronaviruses. IMPORTANCE TGEV is the causative agent of porcine diarrhea, a viral disease that economically affects the pig industry in many countries. However, the molecular mechanisms underlying viral replication remain incompletely understood. Here, we provide evidence of a previously undescribed role of M protein in viral replication during early stages. We also identified HSC70 as a new host factor affecting TGEV infection. We demonstrate that the interaction between M and HSC70 directs TGEV internalization in a manner dependent on CME, thus revealing a novel mechanism for TGEV replication. We believe that this study may change our understanding of the first steps of infection of cells with coronavirus. This study should facilitate the development of anti-TGEV therapeutic agents by targeting the host factors and may provide a new strategy for the control of porcine diarrhea. [ABSTRACT FROM AUTHOR]

A portable method for on-site detection of three mycotoxins was developed based on a sonic toothbrush, microfluidic chip and smartphone. Our method could complete all procedures, including sample pretreatment, signal conversion and processing, without any sophisticated instruments. The limits of detection for these mycotoxins were lower than the limit values in cereals in the standards of China and the European Union. [ABSTRACT FROM AUTHOR]

The article discusses a study that examines the effect of intracortical micro-stimulation on the dynamics of a basal ganglia microcircuit model.

A new anomaly detection scheme based on growing structure multiple model system (GSMMS) is proposed in this paper to detect and quantify the effects of anomalies. The GSMMS algorithm combines the advantages of growing self-organizing networks with efficient local model parameter estimation into an integrated framework for modeling and identification of general nonlinear dynamic systems. The identified model then serves as a foundation for building an effective anomaly detection and fault diagnosis system. By utilizing the information about system operation region provided by the GSMMS, the residual errors can be analyzed locally within each operation region. This local decision making scheme can accommodate for unequally distributed residual errors across different operational regions. The performance of the newly proposed method is evaluated through anomaly detection and quantification in an electronically controlled throttle system, which is simulated using a high-fidelity engine simulation software package provided by a major automotive manufacturer for control system development. [ABSTRACT FROM AUTHOR]

Revealing the mechanisms of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry and cell-to-cell spread might provide insights for understanding the underlying mechanisms of viral pathogenesis, tropism, and virulence. The signaling pathways involved in SARS-CoV-2 entry and viral spike-mediated cell-to-cell fusion remain elusive. In the current study, we found that macropinocytosis inhibitors significantly suppressed SARS-CoV-2 infection at both the entry and viral spike-mediated cell-to-cell fusion steps. We demonstrated that SARS-CoV-2 entry required the small GTPase Rac1 and its effector kinase p21-activated kinase 1 by dominant-negative and RNAi assays in human embryonic kidney 293T-angiotensin-converting enzyme 2 cells and that the serine protease transmembrane serine protease 2 reversed the decrease in SARS-CoV-2 entry caused by the macropinocytosis inhibitors. Moreover, in the cell-to-cell fusion assay, we confirmed that macropinocytosis inhibitors significantly decreased viral spike-mediated cell-to-cell fusion. Overall, we provided evidence that SARS-CoV-2 utilizes a macropinocytosis pathway to enter target cells and to efficiently promote viral spike-mediated cell-to-cell fusion. [ABSTRACT FROM AUTHOR]

Porcine epidemic diarrhea virus (PEDV) causes a porcine disease associated with swine epidemic diarrhea. Different antagonistic strategies have been identified, and the mechanism by which PEDV infection impairs the production of interferon (IFN) and delays the activation of the IFN response to escape host innate immunity has been determined, but the pathogenic mechanisms of PEDV infection remain enigmatic. Our preliminary results revealed that endogenous F-box and WD repeat domain-containing 7 (FBXW7) protein, the substrate recognition component of the SCF-type E3 ubiquitin ligase, is downregulated in PEDV-infected Vero E6 cells, according to the results from an isobaric tags for relative and absolute quantification (iTRAQ) analysis. Overexpression of FBXW7 in target cells makes them more resistant to PEDV infection, whereas ablation of FBXW7 expression by small interfering RNA (siRNA) significantly promotes PEDV infection. In addition, FBXW7 was verified as an innate antiviral factor capable of enhancing the expression of RIG-I and TBK1, and it was found to induce interferon-stimulated genes (ISGs), which led to an elevated antiviral state of the host cells. Moreover, we revealed that PEDV nonstructural protein 2 (nsp2) interacts with FBXW7 and targets FBXW7 for degradation through the K48-linked ubiquitin-proteasome pathway. Consistent with the results proven in vitro, FBXW7 reduction was also confirmed in different intestinal tissues from PEDV-infected specific-pathogen-free (SPF) pigs. Taken together, the data indicated that PEDV has evolved with a distinct antagonistic strategy to circumvent the host antiviral response by targeting the ubiquitin-proteasome-mediated degradation of FBXW7. Our findings provide novel insights into PEDV infection and pathogenesis. IMPORTANCE To counteract the host antiviral defenses, most viruses, including coronaviruses, have evolved with diverse strategies to dampen host IFN-mediated antiviral response, by interfering with or evading specific host regulators at multiple steps of this response. In this study, a novel antagonistic strategy was revealed showing that PEDV infection could circumvent the host innate response by targeted degradation of endogenous FBXW7 in target cells, a process that was verified to be a positive modulator for the host innate immune system. Degradation of FBXW7 hampers host innate antiviral activation and facilitates PEDV replication. Our findings reveal a new mechanism exploited by PEDV to suppress the host antiviral response. [ABSTRACT FROM AUTHOR]

Porcine parvovirus (PPV) NS1, the major nonstructural protein of this virus, plays an important role in PPV replication. We show, for the first time, that NS1 dynamically shuttles between the nucleus and cytoplasm, although its subcellular localization is predominantly nuclear. NS1 contains two nuclear export signals (NESs) at amino acids 283 to 291 (designated NES2) and amino acids 602 to 608 (designated NES1). NES1 and NES2 are both functional and transferable NESs, and their nuclear export activity is blocked by leptomycin B (LMB), suggesting that the export of NS1 from the nucleus is dependent upon the chromosome region maintenance 1 (CRM1) pathway. Deletion and site-directed mutational analyses showed that NS1 contains a bipartite nuclear localization signal (NLS) at amino acids 256 to 274. Coimmunoprecipitation assays showed that NS1 interacts with importins a5 and a7 through its NLS. The overexpression of CRM1 and importins a5 and a7 significantly promoted PPV replication, whereas the inhibition of CRM1- and importin α/β-mediated transport by specific inhibitors (LMB, importazole, and ivermectin) clearly blocked PPV replication. The mutant viruses with deletions of the NESs or NLS motif of NS1 by using reverse genetics could not be rescued, suggesting that the NESs and NLS are essential for PPV replication. Collectively, these findings suggest that NS1 shuttles between the nucleus and cytoplasm, mediated by its functional NESs and NLS, via the CRM1-dependent nuclear export pathway and the importin α/β-mediated nuclear import pathway, and PPV proliferation was inhibited by blocking NS1 nuclear import or export. [ABSTRACT FROM AUTHOR]

Rotaviruses are the causative agents of severe and dehydrating gastroenteritis in children, piglets, and many other young animals. They replicate their genomes and assemble double-layered particles in cytoplasmic electron-dense inclusion bodies called "viroplasms." The formation of viroplasms is reportedly associated with the stability of microtubules. Although material transport is an important function of microtubules, whether and how microtubule-based transport influences the formation of viroplasms are still unclear. Here, we demonstrate that small viroplasms move and fuse in living cells. We show that microtubule-based dynein transport affects rotavirus infection, viroplasm formation, and the assembly of transient enveloped particles (TEPs) and triple-layered particles (TLPs). The dynein intermediate chain (DIC) is shown to localize in the viroplasm and to interact directly with nonstructural protein 2 (NSP2), indicating that the DIC is responsible for connecting the viroplasm to dynein. The WD40 repeat domain of the DIC regulates the interaction between the DIC and NSP2, and the knockdown of the DIC inhibited rotaviral infection, viroplasm formation, and the assembly of TEPs and TLPs. Our findings show that rotavirus viroplasms hijack dynein transport for fusion events, required for maximal assembly of infectious viral progeny. This study provides novel insights into the intracellular transport of viroplasms, which is involved in their biogenesis. IMPORTANCE Because the viroplasm is the viral factory for rotavirus replication, viroplasm formation undoubtedly determines the effective production of progeny rotavirus. Therefore, an understanding of the virushost interactions involved in the biogenesis of the viroplasm is critical for the future development of prophylactic and therapeutic strategies. Previous studies have reported that the formation of viroplasms is associated with the stability of microtubules, whereas little is known about its specific mechanism. Here, we demonstrate that rotavirus viroplasm formation takes advantage of microtubule-based dynein transport mediated by an interaction between NSP2 and the DIC. These findings provide new insight into the intracellular transport of viroplasms. [ABSTRACT FROM AUTHOR]

The explores the molecular design of stapled pentapeptides as building blocks of self-assembled coiled coil–like fibers. It mentions that peptide self-assembly inspired by natural superhelical coiled coils has been actively pursued but remains challenging due to limited helicity of short peptides. It discusses a study that expands the chemical space of coiled coil assemblies and provides guidance for their design.

Nine prenjdated and geraidatedx anthones were synthesized in two steps with total yields rangng from 11% to 36%. All of the compounds were first reported. Then, the antitumor, anti-tyrosinase, anti-pancreatic lipase, antifungal and antibacterial activities of all or part of compounds 1-9 were evaluated. Compound 9 exhibited dear antitumor activity, and its cytotoxicity against MCF-7 and MDA-MB-231 cells was stronger compared with cisplatin. Compounds 1-4 and 6-7 also exhibited certain activity other than the antitumor activity described above. These results demonstrated that compounds 14, 6-7 and 9 were very promising leads for further structural modification. [ABSTRACT FROM AUTHOR]

Porcine deltacoronavirus (PDCoV) is a pathogen belonging to the genus Deltacoronavirus that in 2014 caused outbreaks of piglet diarrhea in the United States. To identify suitable therapeutic targets, a more comprehensive understanding of the viral entry pathway is required, particularly of the role of proteases. Here, we identified the proteases that activate the viral spike (S) glycoprotein to initiate cell entry and also pinpointed the host-cellular pathways that PDCoV uses for entry. Our results revealed that cathepsin L (CTSL) and cathepsin B (CTSB) in lysosomes and extracellular trypsin in cell cultures independently activate the S protein for membrane fusion. Pretreating the cells with the lysosomal acidification inhibitor bafilomycin-A1 (Baf-A1) completely inhibited PDCoV entry, and siRNA-mediated ablation of CTSL or CTSB expression significantly reduced viral infection, indicating that PDCoV uses an endosomal pathway for entry. Of note, trypsin treatment of cell cultures also activated PDCoV entry, even when the endosomal pathway was inhibited. This observation indicated that trypsin-induced S protein cleavage and activation in cell cultures enables viral entry directly from the cell surface. Our results provide critical insights into the PDCoV infection mechanism, uncovering two distinct viral entry pathways: one through cathepsin L and cathepsin B in the endosome and another via a protease at the cell surface. Because PDCoV infection sites represent a proteases-rich environment, these findings suggest that endosome inhibitor treatment alone is insufficient to block PDCoV entry into intestinal epithelial cells in vivo. Therefore, approaches that inhibit viral entry from the cell membrane should also be considered. [ABSTRACT FROM AUTHOR]

Upper Neoproterozoic successions in the North China and nearby Chaidam blocks are poorly documented. North China successions typically consist of a diamictite unit overlain by siltstone, sandstone, or slate. Similar successions occur in Chaidam, although a cap carbonate lies atop the diamictite Unit. The diamictites in both blocks have been variously interpreted as Cryogenian, Ediacaran, or Cambrian glacial deposits. In this paper, we describe problematic macrofossils collected from slate of the upper Zhengmuguan Formation in North China and sandstone of the Zhoujieshan Formation in Chaidam; both fossiliferous formations conformably overlie the aforementioned diamictites. Some of these fossils were previously interpreted as animal traces. Our study recognizes four genera and five species—Helanoichnus helanensis Yang in Yang and Zheng, 1985, Palaeopascichnus minimus n. sp., Palaeopascichnus Ineniscafus n. sp., Horodyskia moniliformis? Yochelson and Fedonkin, 2000, and Shaanxilithes cf. ningqiangensis Xing et al., 1984. None of these taxa can be interpreted as animal traces. Instead, they are problematic body fossils of unresolved phylogenetic affinities. The fundamental bodyplan similarity between Horodyskia and Palaeopascichnus, both with serially repeated elements, indicates a possible phylogenetic relationship. Thus, at least some Ediacaran organisms may have a deep root because Horodyskia also occurs in Mesoproterozoic successions. Among the four genera reported here, Palaeopascichnus Palij, 1976 and Shaanxilithes Xing et al., 1984 have been known elsewhere in upper Ediacaran successions, including the Dengying Formation (551–542 Ma) in South China. If these two genera have biostratigraphic significance, the fossiliferous units in North China and Chaidam may be upper Ediacaran as well. Thus, the underlying diamictites in North China and Chaidam cannot be of Cambrian age, although their correlation with Ediacaran and Cryogenian glaciations remains unclear. As no other Neoproterozoic diamictite intervals are known in North China and Chaidam, perhaps only one Neoproterozoic glaciation is recorded in that area. [ABSTRACT FROM AUTHOR]