Cytoskeleton remodeling mediated by circRNA-YBX1 phase separation suppresses the metastasis of liver cancer.

Metastasis, especially intrahepatic, is a major challenge for hepatocellular carcinoma (HCC) treatment. Cytoskeleton remodeling has been identified as a vital process mediating intrahepatic spreading. Previously, we reported that HCC tumor adhesion and invasion were modulated by circular RNA (circRNA), which has emerged as an important regulator of various cellular processes and has been implicated in cancer progression. Here, we uncovered a nuclear circRNA, circASH2, which is preferentially lost in HCC tissues and inhibits HCC metastasis by altering tumor cytoskeleton structure. Tropomyosin 4 (TPM4), a critical binding protein of actin, turned out to be the major target of circASH2 and was posttranscriptionally suppressed. Such regulation is based on messenger RNA (mRNA)/precursormRNA splicing and degradation process. Furthermore, liquid-liquid phase separation of nuclear Y-box binding protein 1 (YBX1) enhanced by circASH2 augments TPM4 transcripts decay. Together, our data have revealed a tumor-suppressive circRNA and, more importantly, uncovered a fine regulation mechanism for HCC progression.

A 20-gene mutation signature predicts the efficacy of immune checkpoint inhibitor therapy in advanced non-small cell lung cancer patients.

BACKGROUND: There is an unmet need to identify novel predictive biomarkers that enable more accurate identification of individuals who can benefit from immune checkpoint inhibitor (ICI) therapy. The US FDA recently approved tumor mutational burden (TMB) score of ≥ 10 mut/Mb as a threshold for pembrolizumab treatment of solid tumors. Our study aimed to test the hypothesis that specific gene mutation signature may predict the efficacy of ICI therapy more precisely than high TMB (≥ 10). METHODS: We selected 20 candidate genes that may predict for the efficacy of ICI therapy by the analysis of data from a published cohort of 350 advanced non-small cell lung cancer (NSCLC) patients. Then, we compared the influences of various gene mutation signatures on the efficacy of ICI treatment. They were also compared with PD-L1 and TMB. The Kaplan-Meier method was utilized to evaluate the prognosis univariates, while selected univariates were adopted to develop a systematic nomogram. RESULTS: A high mutation signature, where three or more of the 20 selected genes were mutated, was associated with the significant benefits of ICI therapy. Specifically, patients with high mutation signature were confirmed to have better prognosis for ICI treatment, compared with those with wild type (the median PFS: 7.17 vs. 2.90 months, p = 0.0004, HR = 0.47 (95% [CI]:0.32-0.68); the median OS: unreached vs. 9 months, p = 1.8E-8, HR = 0.17 (95% [CI]:0.11-0.25)). Moreover, those patients with the high mutation signature achieved significant ICI treatment benefits, while there was no difference of OS and PFS between patients without the signature but TMB-H (≥ 10) and those without the signature and low TMB(< 10). Finally, we constructed a novel nomogram to evaluate the efficacy of ICI therapy. CONCLUSION: A high mutational signature with 3 or more of the 20-gene panel could provide more accurate predictions for the outcomes of ICI therapy than TMB ≥ 10 in NSCLC patients.

Efficient Visible-Light-Activated Ultra-Long Room-Temperature Phosphorescence Triggered by Multi-Esterification.

The development of ultra-long room-temperature phosphorescence (UL-RTP) in processable amorphous organic materials is highly desirable for applications in flexible displays, anti-counterfeiting, and bio-imaging. However, achieving efficient UL-RTP from amorphous materials remains a challenging task, especially with activation by visible light and a bright afterglow. Here we report a general and rational molecular-design strategy to enable efficient visible-light-excited UL-RTP by multi-esterification of a rigid large-plane phosphorescence core. Notably, multi-esterification minimizes the aggregation-induced quenching and accomplishes a 'four birds with one stone' possibility in the generation and radiation process of UL-RTP: i) shifting the excitation from ultraviolet light to blue-light through enhancing the transition dipole moment of low-lying singlet-states, ii) facilitating the intersystem crossing process through the incorporation of lone-pair electrons, iii) boosting the decay process of long-lived triplet excitons resulting from a significantly increased transition dipole moment, and iv) reducing the intrinsic triplet nonradiative decay by substitution of high-frequency vibrating hydrogen atoms. All these factors synergistically contribute to the most efficient and stable visible-light-stimulated UL-RTP (lifetime up to 2.01 s and efficiency up to 35.4 % upon excitation at 450 nm) in flexible films using multi-esterified coronene, which allows high-tech applications in single-component time-delayed white light-emitting diodes and information technology based on flashlight-activated afterglow encryption.

Fluorinated Hyaluronic Acid Encapsulated Perfluorocarbon Nanoparticles as Tumor-Targeted Oxygen Carriers to Enhance Radiotherapy.

The efficacy of radiotherapy is significantly constricted by tumor hypoxia. To overcome this obstacle, one promising approach is to use the perfluorocarbon-based O2 carriers combined with hyperoxic respiration to relieve tumor hypoxia. However, this passively transported oxygen carrier during hyperoxic respiration is prone to cause systemic oxidative stress and toxicity, which further limits its clinical application. Herein, we fabricate O2@PFC@FHA NPs for safe and specific oxygen delivery into tumors by using the fluorinated hyaluronic acid to encapsulate O2-saturated perfluorocarbon. Due to the interaction between HA and CD44 receptors, more FHA@PFC NPs accumulated in the tumor and the O2@PFC@FHA NPs significantly relieved tumor hypoxia. Notably, RT plus O2@PFC@FHA NPs resulted in almost threefold therapeutic improvement compared with RT without obvious systemic toxicity. Therefore, the O2@FHA@PFC NPs may have great potential to enhance the therapeutic efficacy of radiotherapy in the clinic.

Non-clinical immunogenicity, biodistribution and toxicology evaluation of a chimpanzee adenovirus-based COVID-19 vaccine in rat and rhesus macaque.

Coronavirus Disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in 2019 has rapidly expanded into a serious global pandemic. Due to the high morbidity and mortality of COVID-19, there is an urgent need to develop safe and effective vaccines. AdC68-19S is an investigational chimpanzee adenovirus serotype 68 (AdC68) vector-based vaccine which encodes the full-length spike protein of SARS-CoV-2. Here, we evaluated the immunogenicity, biodistribution and safety profiles of the candidate vaccine AdC68-19S in Sprague Dawley (SD) rat and rhesus macaque under GLP conditions. To characterize the biodistribution profile of AdC68-19S, SD rats were given a single intramuscular injection of AdC68-19S 2 × 1011 VP/dose. Designated organs were collected on day 1, day 2, day 4, day 8 and day 15. Genomic DNA was extracted from all samples and was further quantified by real-time quantitative polymerase chain reaction (qPCR). To characterize the toxicology and immunogenicity profiles of AdC68-19S, the rats and rhesus macaques were injected intramuscularly with AdC68-19S up to 2 × 1011vp/dose or 4 × 1011vp/dose (2 and fourfold the proposed clinical dose of 1 × 1011vp/dose) on two or three occasions with a 14-day interval period, respectively. In addition to the conventional toxicological evaluation indexes, the antigen-specific cellular and humoral responses were evaluated. We proved that multiple intramuscular injections could elicit effective and long-lasting neutralizing antibody responses and Th1 T cell responses. AdC68-19S was mainly distributed in injection sites and no AdC68-19S related toxicological reaction was observed. In conclusion, these results have shown that AdC68-19S could induce an effective immune response with a good safety profile, and is a promising candidate vaccine against COVID-19.

A peptide translated from circPPP1R12A promotes the malignancy of non-small cell lung cancer cells through AKT signaling pathway.

BACKGROUND: Recent literature have indicated that the malignancy of cancer cells is modulated by hsa_circ_0000423 (named circPPP1R12A) through the way of translating protein. Herein, we investigated the role and latent mechanisms of circPPP1R12A in Non-Small Cell Lung Cancer (NSCLC). METHODS: CircPPP1R12A expression was measured by qRT-PCR. The malignancy of NSCLC was determined by CCK-8, TUNEL assay, Wound healing, Transwell and Western blotting assays. The underlying mechanisms of circPPP1R12A were confirmed by Western blotting and qRT-PCR assays. RESULTS: CircPPP1R12A expression in NSCLC tissues was higher than that of neighboring normal tissues. CircPPP1R12A showed an upregulated expression in NSCLC cells. Upregulation of circPPP1R12A could promote the cell viability of NSCLC cells and reduce the apoptosis of NSCLC cells, while it could not promote cell invasion and migration. The reduction of cell viability and apoptosis was discovered in NSCLC cells with the silencing of circPPP1R12A, but circPPP1R12A knockdown does not inhibit cell invasion and migration. There was something interesting that circPPP1R12A encoding protein circPPP1R12A-73aa was found in NSCLC cells. Mutations in circPPP1R12a-73AA might disrupt the function of circPPP1ra-73AA in A549 and H1299 cells. Next, we found that circPPP1R12A caused the increased growth of NSCLC cells by activating AKT signaling pathway. CONCLUSION: In summary, our study proved that NSCLC cell proliferation was promoted by circPPP1R12A-73aa translated from circPPP1R12A through the AKT pathway, which could throw some light on the understanding of the mechanism of NSCLC.

The Learning Curve and Importance of Collaboration in Endoscopic Thyroidectomy Via Breast Areola Approach: A Single Surgical Team's Experience of 100 Patients.

BACKGROUND: Endoscopic thyroidectomy is popular among young patients because of its excellent cosmetic outcomes. But it takes a long time to become proficient and competent for surgeons. In addition, collaboration plays a critical role in endoscopic thyroidectomy. Our research aims to evaluate the learning curve of endoscopic thyroidectomy via breast areola approach, provide details of this approach, and demonstrate the importance of collaboration. METHODS: The authors retrospectively analyzed 100 cases of benign and malignant thyroid disease who underwent endoscopic thyroidectomy via breast areola approach between January 2015 and December 2020, which were performed by the same group of surgeons with little experience of endoscopic thyroidectomy. The learning curve was analyzed by moving average method. The mean operation time, blood loss, tumor size, postoperative complications were used to determine learning curve progression. RESULTS: The learning curve in the first 30 cases were uplifted, stable at 30 to 60 cases and declined in the following cases. The mean operation time and blood loss decreased significant after the first 30 cases and again after the first 60 cases. And there was no difference in postoperative complications. CONCLUSIONS: A well-trained surgeon with experience in conventional open thyroidectomy can significantly reduce the total operation time by studying the learning curve. The key steps including establishment of working space and reaching for recurrent laryngeal nerve. A stable level can be achieved after 30 cases. More than 60 cases are required to become proficient. A successful endoscopic thyroid surgery requires a stable team.

Optimal Dihedral Angle in Twisted Donor-Acceptor Organic Emitters for Maximized Thermally Activated Delayed Fluorescence.

The twisted donor-acceptor (D-A) organic formwork with a large dihedral angle (θDA ) is usually adopted to narrow the singlet-triplet energy gap for obtaining excellent thermally activated delayed fluorescence (TADF) emitters. However, the dependence of overall TADF properties on θDA has not been systematically investigated to this day. Taking new designed CzBP, CzBP-1M and CzBP-2M via introducing methyl as investigated models, it is found that (i) with increasing θDA , the charge transfer component in S1 is larger than that in T1 in varying degrees, leading to non-monotonic spin-orbit couplings; (ii) the electron-vibration couplings between S1 and T1 states become the largest when θDA approaching 80°, facilitating phonon-driven up-conversion; (iii) the overall TADF rate reaches a peak at θDA ≈80°. By this, the TADF on/off switching is realized via methyl moiety for regulating θDA from theoretical prediction to experimental confirmation. Importantly, the θDA near 80° would be a good descriptor for screening excellent D-A type TADF emitters.

LPAR5 promotes thyroid carcinoma cell proliferation and migration by activating class IA PI3K catalytic subunit p110ß.

Lysophosphatidic acid receptor 5 (LPAR5) is involved in mediating thyroid cancer progression, but the underlying mechanism needs to be further revealed. In this study, we confirmed that LPAR5 is upregulated in papillary thyroid carcinoma (PTC), especially in BRAF-like PTC, by analyzing The Cancer Genome Atlas (TCGA) database and performing immunohistochemistry assay in human thyroid cancer tissues. LPAR5-specific antagonist TC LPA5 4 treatment inhibited CGTH-W3, TPC-1, B-CPAP, and BHT-101 cell proliferation, CGTH-W3 and TPC-1 cell migration significantly. In vivo, TC LPA5 4 treatment could delay CGTH-W3 xenograft growth in nude mice. We also found that LPAR5-specific antagonist TC LPA5 4, PI3K inhibitor wortmannin, or mTOR inhibitor rapamycin pretreatment abrogated phosphorylation of Akt and p70S6K1 stimulated by LPA in CGTH-W3 and TPC-1 cells. Stimulating CGTH-W3 cells transfected with pEGFPC1-Grp1-PH fusion protein with LPA resulted in the generation of phosphatidylinositol (3,4,5)-triphosphate, which indicates that PI3K was activated by LPA directly. The p110ß-siRNA instead of p110α-siRNA transfection abrogated the increase of levels of phosphorylated Akt and S6K1 stimulated by LPA. Furthermore, immunoprecipitation assay confirmed an interaction between LPAR5 and p110ß. Overall, we provide new insights that the downregulation of LPAR5 decreased the proliferation and migration phenotype via the PI3K/Akt pathway. Inhibition of LPAR5 or the PI3K/Akt signal may be a novel therapeutic strategy for treating thyroid cancer.

Cisplatin synergizes with PRLX93936 to induce ferroptosis in non-small cell lung cancer cells.

Ferroptosis is a newly identified type of regulated cell death that is affected by lipid peroxidation and reactive oxygen species (ROS). In the current study, we showed that cisplatin and PRLX93936, an analog of erastin that has been tested in clinical trials, demonstrated synergistic effects against non-small cell lung cancer (NSCLC) cells. Cotreatment with cisplatin and PRLX93936 induced ferroptosis, as evidenced by the upregulation of ROS, lipid peroxidation and Fe2+. Further investigation revealed that cotreatment with cisplatin and PRLX93936 inhibited GPX4 and that overexpression of GPX4 prevented cell death. Moreover, the Nrf2/Keap1 pathway also regulated the sensitivity to cisplatin and PRLX93936 in NSCLC cells. Nrf2 silencing increased this sensitivity while inhibition of Keap1 attenuated it. Overall, our data reveal a new effective treatment for NSCLC by synergizing cisplatin and PRLX93936 to induce ferroptosis.

Circular RNA circß-catenin aggravates the malignant phenotype of non-small-cell lung cancer via encoding a peptide.

BACKGROUND: More and more evidences demonstrate that circular RNAs (circNRAs) can encode protein. As a circRNA with translation capabilities, outcomes of circß-catenin in non-small cell lung cancer (NSCLC) still need to be explored. METHOD: The research methods of circß-catenin in the article include qRT-PCR, wound healing assay, CCK-8, colony formation, and Transwell assay. Western blotting and immunofluorescence were provided to detect protein expression levels and peptide encoded by circß-catenin, respectively. RESULTS: A prominently higher circß-catenin expression was found in NSCLC tissues. Silencing of circß-catenin was able to inhibit NSCLC cell migrating, invasive, and proliferative phenotypes. Overexpression of circß-catenin could enhance the migrating, invasive, and proliferative phenotypes of NSCLC cells. Importantly, circß-catenin was found to encode a peptide in NSCLC cells. Silencing or overexpression of circß-catenin could reduce or increase ß-catenin protein expression via suppressing the degradation of ß-catenin. CONCLUSION: Circß-catenin could promote NSCLC cell malignant phenotypes via peptide-regulated ß-catenin pathway. Our study provided a new understanding for the mechanisms of NSCLC.

A novel circulating miRNA-based signature for the early diagnosis and prognosis prediction of non-small-cell lung cancer.

BACKGROUND: Non-small-cell lung cancer (NSCLC) is a significant public health issue worldwide. The aim of our study was to develop a serum miRNA-based molecular signature for the early detection and prognosis prediction of NSCLC. METHODS: The significantly altered circulating miRNAs were profiled in GSE24709. The top ten upregulated miRNAs were miR-432, miR-942, miR-29c-5p, miR-601, miR-613, miR-520d-3p, miR-1261, miR-132-5p, miR-302b, and miR-154-5p, while the top ten downregulated miRNAs were miR-562, miR-18b, miR-9-3p, miR-154-3p, miR-20b, miR-18a, miR-487a, miR-20a, miR-103, and miR-144. Then, the top four upregulated serum miRNAs (miR-432, miR-942, miR-29c-5p, and miR-601) were validated by real-time quantitative PCR. The clinical significance of two candidate serum miRNAs, miR-942 and miR-601, was further explored. RESULTS: Our results showed that the expression levels of serum miR-942 and serum miR-601 were significantly upregulated in NSCLC. In addition, serum miR-942 and serum miR-601 showed better performance than CEA, CYFRA21-1, and SCCA for early diagnosis of NSCLC. Combining serum miR-942 and serum miR-601 enhanced the efficacy of detecting early-stage NSCLC. Moreover, high serum miR-942 and serum miR-601 were both associated with adverse clinical variables and poor survival. The NSCLC patients with simultaneously high serum miR-942 and serum miR-601 suffered worst clinical outcome, while those with simultaneously low serum miR-942 and serum miR-601 had most favorable outcome. The multivariate analysis showed that serum miR-942 and serum miR-601 were independent prognostic factors for NSCLC. CONCLUSIONS: Taken together, serum miR-942 and serum miR-601 might serve as a promising molecular signature for the early detection and prognosis prediction of NSCLC.

An alternative method for analyzing dimensional interactions of urban carrying capacity: Case study of Guangdong-Hong Kong-Macao Greater Bay Area.

Most previous studies on comprehensive urban carrying capacity (UCC) have estimated UCC levels and comparatively analyzed the heterogeneity of the sample cities. Very few researchers have focused on the interaction effects between different categories of UCC based on synergetic theory. To fill this gap, we constructed a panel vector autoregressive (PVAR) model to study 11 cities in the Guangdong-Hong Kong-Macao Greater Bay Area from 2000 to 2016. The ultimate goal of this study is to improve comprehensive UCC levels by forming a virtuous circle of mutual reinforcement between the four types of carrying capacity. To do so, the interaction mechanisms of the four subsystems are examined. Results show that (a) only transportation and social carrying capacity had causality between them as per the Granger causality test; (b) all four carrying capacities can support themselves (i.e., the development of economic conditions helps to improve social carrying capacity and the improvement of social carrying capacity helps to improve environmental carrying capacity); and (c) both the four carrying capacities are mostly affected by their own fluctuations. Overall transportation carrying capacity is the most important driving force among the four subsystems that interact with each other; followed by economic carrying capacity, which has promotion effect on the social and environmental aspects; social carrying capacity poses impact on the environmental dimension but not vice versa. Policy suggestions and future research directions are highlighted in the final section.

New Wine in Old Bottles: Prolonging Room-Temperature Phosphorescence of Crown Ethers by Supramolecular Interactions.

Supramolecular macrocyclic hosts have long been used in smart materials. However, their triplet emission and regulation at crystal level is rarely studied. Herein, ultralong and universal room-temperature phosphorescence (RTP) is reported for traditional crown ethers. A supramolecular strategy involving chain length adjustment and morphological locking through complexation with K+ was explored as a general method to tune the phosphorescence lifetime in the solid state. A maximum 10-fold increase of lifetime after complex formation accompanied with by invisible to visible phosphorescence was achieved. A deep encryption based on this activated RTP strategy was also facilely fabricated. This work thus opens a new world for supramolecular macrocycles and their intrinsic guest responsiveness offers a new avenue for versatile smart luminescent materials.

Molecular and stable isotopic evidence for the occurrence of nitrite-dependent anaerobic methane-oxidizing bacteria in the mangrove sediment of Zhangjiang Estuary, China.

Nitrite-dependent anaerobic methane oxidation (n-damo), which is mediated by "Candidatus Methylomirabilis oxyfera-like" bacteria, is unique in linking the carbon and nitrogen cycles. However, the niche and activity of n-damo bacteria in the mangrove ecosystem have not been confirmed. Here, we report the occurrence of the n-damo process in the mangrove wetland of the Zhangjiang Estuary, China. The widespread occurrence of n-damo bacteria in mangrove wetland was confirmed using real-time quantitative polymerase chain reaction (qPCR) assay, which showed that the abundance of Methylomirabilis oxyfera-like bacterial 16S rRNA and pmoA genes ranged from 2.43 × 106 to 2.09 × 107 and 2.07 × 106 to 3.38 × 107copies per gram of dry soil in the examined sediment cores. The highest amount of targeting genes was all detected in the upper layer (0-20 cm). Phylogenetic analyses of n-damo bacterial 16S rRNA and pmoA genes illustrated the depth-specific distribution and high diversity of n-damo bacteria in the mangrove wetland. Stable isotope experiments further confirmed the occurrence of n-damo in the examined mangrove sediments, and the potential n-damo rates ranged from 25.93 to 704.08 nmol CO2 per gram of dry soil per day at different depths of the sediment cores, with the n-damo being more active in the upper layer of the mangrove sediments. These results illustrate the existence of active M. oxyfera-like bacteria and indicate that the n-damo process is a previously overlooked microbial methane sink in the mangrove wetlands.

Manipulation of Molecular Aggregation States to Realize Polymorphism, AIE, MCL, and TADF in a Single Molecule.

Multifunctional emitting materials are scarce and need to be further explored. Now, a newly anthraquinone derivative, 2-(phenothiazine-10-yl)-anthraquinone (PTZ-AQ) was designed and synthesized and found to demonstrate polymorphism, multi-color emission, aggregation-induced emission (AIE), mechanochromic luminescence (MCL), and thermally activated delayed fluorescence (TADF) in its different solid forms. It is shown for the first time that TADF properties of a compound can be systematically tuned via its aggregation state. The optimized PTZ-AQ crystal shows a small singlet-triplet energy splitting of 0.01 eV and exhibits red TADF with a photoluminescence quantum yield as high as 0.848. This study shows that the unique multiple functions can be integrated into one single compound through controlling the aggregation states, which provides a new strategy for the investigation and application of multifunctional organic materials.

Designing Efficient and Ultralong Pure Organic Room-Temperature Phosphorescent Materials by Structural Isomerism.

Pure organic materials with ultralong room-temperature phosphorescence (RTP) are attractive alternatives to inorganic phosphors. However, they generally show inefficient intersystem crossing (ISC) owing to weak spin-orbit coupling (SOC). A design principle based on the realization of small energy gap between the lowest singlet and triplet states (ΔEST ) and pure ππ* configuration of the lowest triplet state (T1 ) via structural isomerism was used to obtain efficient and ultralong RTP materials. The meta isomer of carbazole-substituted methyl benzoate exhibits an ultralong lifetime of 795.0 ms with a quantum yield of 2.1 %. Study of the structure-property relationship shows that the varied steric and conjugation effects imposed by ester substituent at different positions are responsible for the small ΔEST and pure ππ* configuration of T1 .

Ultrafast Delivery of Aggregation-Induced Emission Nanoparticles and Pure Organic Phosphorescent Nanocrystals by Saponin Encapsulation.

Saponins are a class of naturally occurring bioactive and biocompatible amphiphilic glycosides produced by plants. Some saponins, such as α-hederin, exhibit unique cell membrane interactions. At concentrations above their critical micelle concentration, they will interact and aggregate with membrane cholesterol to form transient pores in the cell membrane. In this project, we utilized the unique permeabilization and amphiphilic properties of saponins for the intracellular delivery of deep-red-emitting aggregation-induced emission nanoparticles (AIE NPs) and pure organic room-temperature phosphorescent nanocrystals (NCs). We found this method to be biocompatible, inexpensive, ultrafast, and applicable to deliver a wide variety of AIE NPs and NCs into cancer cells.

A comparative study on three methods of soil quality evaluation of microtopography in the semi-arid Loess Plateau, China.

Three soil property test data of microtopography in the semi-arid Loess Plateau were used to compare the following three soil quality evaluation methods: correlation coefficient method, factor analysis method and Nemoro index method. The results of these methods were analyzed and compared to determine the most suitable method for comprehensive evaluation of soil quality. While correlation coefficient method and factor analysis method produced similar results, Nemoro index method showed several differences from the othertwo methods and exhibited higher sensitivity in its assessment results. The soil quality index (SQI) parameters of three methods showed consistent scales and variation trends among the various microtopographies, and there was a highly significant linear positive correlation between the SQI parameters of any two given methods. This result suggested that the three methods were all reliable and could be employed for comprehensive assessment of soil quality of microtopography in the study region. However, the Nemoro index method involves relatively uncomplicated mathematics and is very easy to absorb, and thus should be preferentially employed when three grading standards can be identified. The factor analysis method is the next most preferable, followed by correlation coefficient method.

Characteristics of soil moisture in relation to microtopography in the Loess region of Northern Shaanxi, China.

Soil moisture is the primary factor limiting plant growth and vegetation rehabilitation in the loess region of northern Shaanxi, China. This 5-year (2008-2012) study investigated methods of selecting appropriate microsites for vegetation restoration based on efficient use of soil moisture; 5-year data were compared with 56 years of precipitation data using standardized precipitation index. In addition, the effects of microtopography on the spatiotemporal variations of soil moisture were analyzed at the Wuqi Ecological Station of Beijing Forestry University. Results showed that average annual precipitation during last 5 years fell by 12.4% during the growing season compared with 1957-2012 data and soil moisture content at depth of 0-160 cm under went dramatic changes and became relatively low in July and August. Soil moisture content varied in different microtopographical units as follows: gullies > gently-sloped terraces > collapsed soils > undisturbed slopes (control) > furrows > escarpments. The vertical distribution of soil moisture content in different microtopographical units showed dramatic changes at depth of 0-40 cm. Soil moisture content of gently-sloped terraces, gullies, collapsed areas, furrows, and undisturbed slopes was highest at depth of 80-160 cm with a level of instability at depth of 40-80 cm. For gently-sloped terraces and gullies, soil moisture content followed the order of 40-80 cm > 0-40 cm; for collapsed areas, furrows, and undisturbed slopes, soil moisture content follows the order of 0-40 cm > 40-80 cm. For escarpments, soil moisture content varied with depth in a different pattern: 0-40 cm > 80-160 cm > 40-80 cm. This study is of theoretical significance and will help guide the sustainable development of ecological restoration and vegetation rehabilitation in the Loess region.