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This study examines the difference in management forecast quality under mandatory vs. voluntary disclosure in China’s stock markets in terms of management forecasting error (MFE) and value relevance. The results of MFE tests reveal that the disclosure approach is significantly associated with forecast accuracy, and voluntarily disclosed forecasts are more accurate than mandatorily disclosed forecasts. In terms of value relevance, the results are also consistent with the belief that in China’s stock markets, management forecast quality under voluntary disclosure is higher than that under mandatory disclosure.

Background Despite many reports on the characteristics of coronavirus disease 2019 (COVID-19) in Wuhan, China, relatively little is known about the transmission features of COVID-19 outside Wuhan, especially at the provincial level. Methods We collected epidemiological, demographic, clinical, laboratory, radiological and occupation information, along with contact history, of 671 patients with laboratory-confirmed COVID-19 reported from January 23 to February 5, 2020, in Henan province, China. We described characteristics of these cases, compared the diagnostic accuracy and features of blood testing, computed tomography (CT) scans and X-rays, and analysed SARS-CoV-2 transmission sources and patients’ occupations in Henan province. Results The mean age of patients in this case series was 43 years, 56.2% were male and 22.4% had coexisting medical disorders. The death rate was 0.3%. Fourteen patients did not show any symptoms. Lymphocyte percentage was associated with disease severity (χ2 = 6.71, P = 0.035) but had a large variation in each sample group. The mean time from illness onset to diagnosis was 5.6 days. A total of 330 patients had ever lived in or visited Wuhan, 150 had contact with confirmed cases, 323 had been to a hospital and 119 had been to a wet market. There were 33 patients who did not have a traceable transmission source, with 21.2% of these being farmers and 15.2% being workmen. Conclusions Lymphocyte percentage was a sign of severe COVID-19 in general but was not a good diagnostic index. Longer time from illness onset to diagnosis was associated with higher COVID-19 severity, older age, higher likelihood of having coexisting cardiovascular diseases including hypertension, and being male. Farming was found to be a high-risk occupation in Henan province, China.

Aiming at the shortcomings of low efficiency and poor accuracy of the existing pressure sensor pre-tightening parameter measurement system, an automatic multi-axis wrist force sensor pre-tightening parameter measurement system is designed. The multi-axis wrist force sensor module is used to collect real-time tension signal from the loaded hand wheel. After amplification, the signal is transmitted to the multi-channel gating module through RS485 communication module to realize the tested sensing. After fast switching and constant current source power supply control function, the data collector collects the pull signal obtained by multi-axis wrist force pressure sensor and transmits it to the upper computer of the system designed by LabVIEW through RS485 bus. The upper computer controls and collects the pressure sensor according to the pull signal feedback from the data collector, and the pre-tightening displacement of multi-axis wrist force sensor is determined by parameters such as axial displacement and friction resistance moment. The experimental results show that the designed system can fully measure the pre-tightening parameters of the sensor, and the starting moment measurement error is only 0.102%. The system can meet the requirements of batch measurement and calibration of multi-axis wrist force sensor with accuracy of 1%-0.1%.

Summary Androgenetic haploid embryonic stem cells (AG-haESCs) hold great promise for exploring gene functions and generating gene-edited semi-cloned (SC) mice. However, the high incidence of self-diploidization and low efficiency of SC mouse production are major obstacles preventing widespread use of these cells. Moreover, although SC mice generation could be greatly improved by knocking out the differentially methylated regions of two imprinted genes, 50% of the SC mice did not survive into adulthood. Here, we found that the genome-wide DNA methylation level in AG-haESCs is extremely low. Subsequently, downregulation of both de novo methyltransferase Dnmt3b and other methylation-related genes was determined to be responsible for DNA hypomethylation. We further demonstrated that ectopic expression of Dnmt3b in AG-haESCs could effectively improve DNA methylation level, and the high incidence of self-diploidization could be markedly rescued. More importantly, the developmental potential of SC embryos was improved, and most SC mice could survive into adulthood., Graphical Abstract, Highlights • Dnmt3b restores methylation of hypomethylated AG-haESCs • Dnmt3b suppresses self-diploidization of AG-haESCs • Dnmt3b promotes developmental potential of SC embryos • Dnmt3b improves SC mice survival to adulthood, Ectopic expression of Dnmt3b could rescue DNA methylation level in repetitive sequences of hypomethylated AG-haESCs, suppress high incidence of self-diploidization, and promote developmental potential of SC embryos, and most SC mice could survive into adulthood.

Graphical abstract, Specific anti-coronaviral drugs complementing available vaccines are urgently needed to fight the COVID-19 pandemic. Given its high conservation across the betacoronavirus genus and dissimilarity to human proteases, the SARS-CoV-2 main protease (Mpro) is an attractive drug target. SARS-CoV-2 Mpro inhibitors have been developed at unprecedented speed, most of them being substrate-derived peptidomimetics with cysteine-modifying warheads. In this study, Mpro has proven resistant towards the identification of high-affinity short substrate-derived peptides and peptidomimetics without warheads. 20 cyclic and linear substrate analogues bearing natural and unnatural residues, which were predicted by computational modelling to bind with high affinity and designed to establish structure-activity relationships, displayed no inhibitory activity at concentrations as high as 100 μM. Only a long linear peptide covering residues P6 to P5’ displayed moderate inhibition (Ki = 57 µM). Our detailed findings will inform current and future drug discovery campaigns targeting Mpro.

// Bo Wang 1, * , Wei Du 2, * , Yutao Jia 1 , Xiaobai Zhang 1 , Guorui Ma 1 1 Department of Paediatrics, The First Affiliated Hospital of Henan University of Science and Technology, Luoyang, Henan, China 2 Department of Medical Laboratory, Luoyang Central Hospital, Luoyang, Henan, China * These authors have contributed equally to this work Correspondence to: Guorui Ma, email: aquacity@126.com Keywords: type 1 diabetes, cytotoxic T-lymphocyte associated protein 4, polymorphism, risk, meta-analysis Received: October 05, 2016 Accepted: December 13, 2016 Published: January 02, 2017 ABSTRACT Type 1 diabetes (T1D) is a heritable disease associated with multiple genetic variants. This systematic review and meta-analysis assessed the correlation between cytotoxic T-lymphocyte-associated protein 4(CTLA-4) +49A/G polymorphisms and the risk of T1D in children. The random effects model was used to estimate the related odds ratios (ORs) and 95% confidence intervals (CIs). Trial sequential analysis (TSA) was used to determine whether the currently available evidence was sufficient and conclusive. Our results indicated that CTLA-4 gene polymorphisms significantly increased the risk of childhood T1D in an allelic model (G vs. A: OR=1.33, 95%CI=1.19-1.48; I 2 =44.0% and P =0.001for heterogeneity) and a codominant model (GG vs. AA: OR=1.75, 95%CI=1.37-2.24; I 2 =57.5% and P =0.001for heterogeneity; GA vs. AA: OR=1.26, 95%CI=1.09-1.46; I 2 =40.4% and P =0.036for heterogeneity). Subgroup analysis results indicated that the ORs were higher in the Asian population (OR allelic model =1.60, OR GG vs. AA =2.46 and OR GA vs. AA =1.58) than the Caucasian population (OR allelic model ==1.24, OR GG vs. AA =1.55 and OR GA vs. AA =1.19). The TSA results indicated that the evidence of the effect was sufficient. In conclusion, CTLA4 +49A/G polymorphisms increased the risk of T1D in children, and CTLA4 +49A/G can be considered to be a genetic marker for T1D in children.

With the global economic integration and the continuous development of the logistics industry, multi-directional transport in the international position is becoming more and more important, the port is the carrier of the development of multi-vehicle transport. The competition of various countries is no longer the competition of the previous infrastructure and operational capacity, and the construction of a waterless port in the inland will become an effective measure for the sustainable development of Jinan. Taking the development of multi-mode transportation in Jinan as the background, this paper analyzes the strategic environment for the development of inland waterless port in Jinan city and the construction mode of inland waterless port in Jinan city by introducing the multi-mode transportation in Jinan area.

SummaryThe core pluripotency factor Oct4 plays key roles in somatic cell reprogramming through transcriptional control. Here, we profile Oct4 occupancy, epigenetic changes, and gene expression in reprogramming. We find that Oct4 binds in a hierarchical manner to target sites with primed epigenetic modifications. Oct4 binding is temporally continuous and seldom switches between bound and unbound. Oct4 occupancy in most of promoters is maintained throughout the entire reprogramming process. In contrast, somatic cell-specific enhancers are silenced in the early and intermediate stages, whereas stem cell-specific enhancers are activated in the late stage in parallel with cell fate transition. Both epigenetic remodeling and Oct4 binding contribute to the hyperdynamic enhancer signature transitions. The hierarchical Oct4 bindings are associated with distinct functional themes at different stages. Collectively, our results provide a comprehensive molecular roadmap of Oct4 binding in concert with epigenetic rearrangements and rich resources for future reprogramming studies.

The linker histone H1 is critical to maintenance of higher-order chromatin structures and to gene expression regulation. However, H1 dynamics and its functions in embryonic development remain unresolved. Here, we profiled gene expression, nucleosome positions, and H1 locations in early Drosophila embryos. The results show that H1 binding is positively correlated with the stability of beads-on-a-string nucleosome organization likely through stabilizing nucleosome positioning and maintaining nucleosome spacing. Strikingly, nucleosomes with H1 placement deviating to the left or the right relative to the dyad shift to the left or the right, respectively, during early Drosophila embryonic development. H1 occupancy on genic nucleosomes is inversely correlated with nucleosome distance to the transcription start sites. This inverse correlation reduces as gene transcription levels decrease. Additionally, H1 occupancy is lower at the 5′ border of genic nucleosomes than that at the 3′ border. This asymmetrical pattern of H1 occupancy on genic nucleosomes diminishes as gene transcription levels decrease. These findings shed new lights into how H1 placement dynamics correlates with nucleosome positioning and gene transcription during early Drosophila embryonic development.

Drosophila neural development undergoes extensive chromatin remodeling and precise epigenetic regulation. However, the roles of chromatin remodeling in establishment and maintenance of cell identity during cell fate transition remain enigmatic. Here, we compared the changes in gene expression, as well as the dynamics of nucleosome positioning and key histone modifications between the four major neural cell types during Drosophila neural development. We find that the neural progenitors can be separated from the terminally differentiated cells based on their gene expression profiles, whereas nucleosome distribution in the flanking regions of transcription start sites fails to identify the relationships between the progenitors and the differentiated cells. H3K27me3 signal in promoters and enhancers can not only distinguish the progenitors from the differentiated cells but also identify the differentiation path of the neural stem cells (NSCs) to the intermediate progenitor cells to the glial cells. In contrast, H3K9ac signal fails to identify the differentiation path, although it activates distinct sets of genes with neuron-specific and glia-related functions during the differentiation of the NSCs into neurons and glia, respectively. Together, our study provides novel insights into the crucial roles of chromatin remodeling in determining cell type during Drosophila neural development. Keywords: Nucleosome, Histone modification, Neural stem cell, Neuron, Glia

Background: Periplaneta americana is one of the ancient insect groups with the strongest vitality. Periplaneta americana extract (PAE) has been explored as an alternative remedy for many diseases. Although much progress has been made in the study about PAE, the role of the drug in renal disease is rarely reported, especially in renal fibrosis. This study was designed to evaluate the renoprotective effect of PAE treatment to renal fibrosis. Method: An in vivo, unilateral ureteral obstruction (UUO) mouse model was built. Then the mice were treated with PAE (100 mg/kg body weight) once daily by oral gavage, again starting on the day of UUO and continued for 1 week. At the end of 1 week, the mice were sacrificed; kidney samples were collected for further analysis. In vitro, Boston University mouse proximal tubular cells were plated in 35-mm dishes at a density of 0.3 * 106 cells/dish. Then the cells were treated with 5-ng/mL TGF-β1 in serum-free DMEM medium for an indicated length of time. The experimental groups were pretreated with the indicated concentrations of PAE (0.3125 mg/mL). The cells were further cultured for 24 h, and then cells were monitored morphologically or collected for biochemical analyses. Results: Both in vivo and vitro PAE inhibits the expression of FN and alpha-smooth muscle actin and suppresses renal fibrosis. Importantly, PAE protects against renal fibrosis by inhibiting Janus tyrosine kinase 2 (JAK)/signal transducer and activator of transcription 3 (STAT) tyrosine phosphorylation. Conclusion: PAE attenuates renal fibrosis through the suppression of the JAK2/STAT3 pathway.

Leukemia inhibitory factor/Stat3 signaling is critical for maintaining the self-renewal and differentiation potential of mouse embryonic stem cells (mESCs). However, the upstream effectors of this pathway have not been clearly defined. Here, we show that periodic tryptophan protein 1 (Pwp1), a WD-40 repeat-containing protein associated with histone H4 modification, is required for the exit of mESCs from the pluripotent state into all lineages. Knockdown (KD) of Pwp1 does not affect mESC proliferation, self-renewal, or apoptosis. However, KD of Pwp1 impairs the differentiation potential of mESCs both in vitro and in vivo. PWP1 chromatin immunoprecipitation-seq results revealed that the PWP1-occupied regions were marked with significant levels of H4K20me3. Moreover, Pwp1 binds to sites in the upstream region of Stat3. KD of Pwp1 decreases the level of H4K20me3 in the upstream region of Stat3 gene and upregulates the expression of Stat3. Furthermore, Pwp1 KD mESCs recover their differentiation potential through suppressing the expression of Stat3 or inhibiting the tyrosine phosphorylation of STAT3. Together, our results suggest that Pwp1 plays important roles in the differentiation potential of mESCs. Stem Cells 2015;33:661–673

It has long been known that trypanosomes regulate mitochondrial biogenesis during the life cycle of the parasite; however, the mitochondrial protein inventory (MitoCarta) and its regulation remain unknown. We present a novel computational method for genome-wide prediction of mitochondrial proteins using a support vector machine-based classifier with approximately 90% prediction accuracy. Using this method, we predicted the mitochondrial localization of 468 proteins with high confidence and have experimentally verified the localization of a subset of these proteins. We then applied a recently developed parallel sequencing technology to determine the expression profiles and the splicing patterns of a total of 1065 predicted MitoCarta transcripts during the development of the parasite, and showed that 435 of the transcripts significantly changed their expressions while 630 remain unchanged in any of the three life stages analyzed. Furthermore, we identified 298 alternatively splicing events, a small subset of which could lead to dual localization of the corresponding proteins.

Background/Aims: Transforming growth factor β 1 (TGFβ1) plays a critical role in the epithelial-to-mesenchymal transition (EMT) of renal tubular epithelial cells (TECs) during renal injury, a major cause of acute renal failure, renal fibrosis and obstructive nephropathy. However, the underlying molecular mechanisms remain ill-defined. Here, we addressed this question. Methods: Expression of TGFβ1, Snail, and phosphorylated Stat3 was examined by immunohistochemistry in the kidney after induction of unilateral ureteral obstruction (UUO) in mice. In vitro, primary TECs were purified by flow cytometry, and then challenged with TGFβ1 with/without presence of specific inhibitors for phosphorylation of SMAD3 or Stat3. Protein levels were determined by Western blotting. Results: We detected significant increases in Snail and phosphorylated Stat3, an activated form for Stat3, in the kidney after induction of UUO in mice. In vitro, TGFβ1-challenged primary TECs upregulated Snail, in a SMAD3/Stat3 dependent manner. Conclusion: Our study sheds light on the mechanism underlying the EMT of TECs after renal injury, and suggests Stat3 signaling as a promising innovative therapeutic target for prevention of renal fibrosis.

Neuroectoderm is an important neural precursor. However, chromatin remodeling and its epigenetic regulatory roles during the differentiation of human neuroectodermal cells (hNECs) from human embryonic stem cells (hESCs) remain largely unexplored. Here, we obtained hNECs through directed differentiation from hESCs, and determined chromatin states in the two cell types. Upon differentiation, H2A.Z-mediated nucleosome depletion leads to an open chromatin structure in promoters and upregulates expression of neuroectodermal genes. Increase in H3K9ac signals and decrease in H3K27me3 signals in promoters result in an active chromatin state and activate neuroectodermal genes. Conversely, decrease in H3K9ac signals and increase in H3K27me3 signals in promoters repress pluripotency genes. Moreover, H3K9ac signals facilitate the pluripotency factor Sox2 binding to target sites unique to hNECs. Knockdown of the acetyltransferase Kat2b erases H3K9ac signals, disrupts Sox2 binding, and fails the differentiation. Our results demonstrate a hierarchy of epigenetic regulation of gene expression during the differentiation of hNECs from hESCs through chromatin remodeling.

Previous phylogenetic analyses have led to incongruent evolutionary relationships between tree shrews and other suborders of Euarchontoglires. What caused the incongruence remains elusive. In this study, we identified 6845 orthologous genes between seventeen placental mammals. Tree shrews and Primates were monophyletic in the phylogenetic trees derived from the first or/and second codon positions whereas tree shrews and Glires formed a monophyly in the trees derived from the third or all codon positions. The same topology was obtained in the phylogeny inference using the slowly and fast evolving genes, respectively. This incongruence was likely attributed to the fast substitution rate in tree shrews and Glires. Notably, sequence GC content only was not informative to resolve the controversial phylogenetic relationships between tree shrews, Glires, and Primates. Finally, estimation in the confidence of the tree selection strongly supported the phylogenetic affiliation of tree shrews to Primates as a monophyly.

Ferroptosis is an outcome of metabolic disorders and closely linked to liver cancer. However, the mechanism underlying the fine regulation of ferroptosis in liver cancer remains unclear. Here, we have identified two categories of genes: ferroptosis up-regulated factors (FUF) and ferroptosis down-regulated factors (FDF), which stimulate and suppress ferroptosis by affecting the synthesis of GSH. Furthermore, FUF are controlled by one transcription factor HIC1, while FDF controlled by another transcription factor HNF4A. Occurrence of ferroptosis might depend on the histone acetyltransferase KAT2B. Upon stimulation of ferroptosis, dissociation of KAT2B prevents HNF4A from binding to the FDF promoter. This effect happens prior to the recruitment of KAT2B to the FUF promoter, which facilitates HIC1 binding to transcribe FUF. Clinically, HIC1 and HNF4A conversely correlate with tumor stage in liver cancer. Patients with lower HIC1 and higher HNF4A exhibit poorer prognostic outcomes. Disrupting the balance between HIC1 and HNF4A might be helpful in treating liver cancer. Keywords: HIC1, HNF4A, GSH, Acetyltransferase, Promoter, Metabolism

Chromatin remodeling plays a critical role in gene regulation and impacts many biological processes. However, little is known about the relationship between chromatin remodeling dynamics and in vivo cell lineage commitment. Here, we reveal the patterns of histone modification change and nucleosome positioning dynamics and their epigenetic regulatory roles during the in vivo glial differentiation in early Drosophila embryos. The genome-wide average H3K9ac signals in promoter regions are decreased in the glial cells compared to the neural progenitor cells. However, H3K9ac signals are increased in a group of genes that are up-regulated in glial cells and involved in gliogenesis. There occurs extensive nucleosome remodeling including shift, loss, and gain. Nucleosome depletion regions (NDRs) form in both promoters and enhancers. As a result, the associated genes are up-regulated. Intriguingly, NDRs form in two fashions: nucleosome shift and eviction. Moreover, the mode of NDR formation is independent of the original chromatin state of enhancers in the neural progenitor cells.

Neurons are a key component of the nervous system and differentiate from multipotent neural stem cells (NSCs). Chromatin remodeling has a critical role in the differentiation process. However, its in vivo epigenetic regulatory role remains unknown. We show here that nucleosome depletion regions (NDRs) form in both proximal promoters and distal enhancers during NSCs differentiating into neurons in the early Drosophila embryonic development. NDR formation in the regulatory regions involves nucleosome shift and eviction. Nucleosome occupancy in promoter NDRs is inversely proportional to the gene activity. Genes with promoter NDR formation during differentiation are enriched for functions related to neuron development and maturation. Active histone-modification signals (H3K4me3 and H3K9ac) in promoters are gained in neurons in two modes: de novo establishment to high levels or increase from the existing levels in NSCs. The gene sets corresponding to the two modes have different neuron-related functions. Dynamic changes of H3K27ac and H3K9ac signals in enhancers and promoters synergistically repress genes associated with neural stem or progenitor cell-related pluripotency and upregulate genes associated with neuron projection morphogenesis, neuron differentiation, and so on. Our results offer new insights into chromatin remodeling during in vivo neuron development and lay a foundation for its epigenetic regulatory mechanism study of other lineage specification.

Chronic kidney disease is becoming a global public health problem, which will usually cause uremia at the end stage of chronic kidney failure. So far, kidney transplant is the most effective and proper therapy for uremia, however, the short supply of matched donor kidney has been a persistent bottleneck for transplantation. HLA matching of HLA-A, -B and -DRB1 loci is very important for the allocation of kidney transplants. In this study, we investigated genotypes of HLA-A, -B and -DRB1 loci based on 1,464 uremia patients and 10,000 unrelated healthy individuals in Henan province of China, and compared the frequency distribution of these HLA alleles and corresponding haplotypes between patient and healthy groups. We detected 23 HLA-A, 49 HLA-B and 17 HLA-DRB1 alleles in total. The predominant alleles of HLA-A, -B and -DRB1 loci in patients are the same as those in healthy group. The seven most frequent alleles account for about 87%, 50%, and 77% at HLA-A, -B and -DRB1 loci, respectively. The haplotypes (combinations of HLA-A, -B, and -DRB1) with significantly different frequency between patients and controls mostly account for less than 1%. Overall, this suggests that HLA matching is not a potential difficulty for kidney transplant of uremia patients. However, three of the top seven frequent HLA-DRB1 alleles have a significantly different distribution in patients and controls, while only one alleles for HLA-B and zero for HLA-A loci. These HLA-DRB1 alleles may be closely associated with uremia. This study sheds new lights on the composition and difference of HLA genotypes in uremia patients and healthy populations in Central China that can serve as a guide to HLA matching for kidney transplants and a resource for HLA typing-related studies.

There are two main mechanisms of miRNA-mediated gene silencing: either mRNA degradation or translational repression. However, the precise mechanism of target mRNAs regulated by miRNA remains unclear. As a complementary approach to experiment, a computational method was proposed to recognize the mechanism of miRNA-mediated gene silencing in human. We have analyzed extensive features correlated with miRNA-mediated silencing mechanism of mRNA. It is found that, the duplex structure, the number of binding sites and the structural accessibility of target site region are effective factors in determining whether a target mRNA is cleaved or only translationally inhibited. An SVM-based classifier was constructed to predict the regulation mode of miRNA based on these informative features. The results indicated that the approach proposed is effective in distinguishing whether a target mRNA is cleaved or translationally inhibited in human. Furthermore, the web server microDoR (http://reprod.njmu.edu.cn/microdor) has been developed and is freely available for users.

Nucleosome positioning and histone modification play a critical role in gene regulation, but their role during reprogramming has not been fully elucidated. Here, we determined the genome-wide nucleosome coverage and histone methylation occupancy in mouse embryonic fibroblasts (MEFs), induced pluripotent stem cells (iPSCs) and pre-iPSCs. We found that nucleosome occupancy increases in promoter regions and decreases in intergenic regions in pre-iPSCs, then recovers to an intermediate level in iPSCs. We also found that nucleosomes in pre-iPSCs are much more phased than those in MEFs and iPSCs. During reprogramming, nucleosome reorganization and histone methylation around transcription start sites (TSSs) are highly coordinated with distinctively transcriptional activities. Bivalent promoters gradually increase, while repressive promoters gradually decrease. High CpG (HCG) promoters of active genes are characterized by nucleosome depletion at TSSs, while low CpG (LCG) promoters exhibit the opposite characteristics. In addition, we show that vitamin C (VC) promotes reorganizations of canonical, H3K4me3- and H3K27me3-modified nucleosomes on specific genes during transition from pre-iPSCs to iPSCs. These data demonstrate that pre-iPSCs have a more open and phased chromatin architecture than that of MEFs and iPSCs. Finally, this study reveals the dynamics and critical roles of nucleosome positioning and chromatin organization in gene regulation during reprogramming.

To investigate the influence of miRNAs on target gene at transcription levels, we have systematically analyzed the expression profiles by a regression method. The results indicated that the down-regulation level of target mRNA is determined by multiple factors including the length and secondary structure of target mRNA, the structural accessibility of the target site and so on. Furthermore, by comparison of different miRNAs, the results indicated that, in animals, all miRNAs regulate their targets in a similar way.

MicroRNAs (miRNAs) are a class of small non-coding RNAs discovered in recent years, which are found to play important regulatory roles in various organisms. As the number of experimentally validated miRNAs is rapidly increasing, systematic analysis on the characteristics of these known miRNAs is necessary and indispensable, especially for computational prediction of new miRNAs. We extensively analyzed precursor sequences for all experimentally validated mature miRNAs in metazoan species, focusing on the characteristics at the level of primary sequences and secondary structures. An observation over the secondary structures of 2729 miRNA precursors (pre-miRNAs) reveals that these hairpin structures can be approximately classified into two types: one with a hairpin loop, and the other with multiple loops. Interestingly, the two types of pre-miRNAs show significant differences in both sequence and structure characteristics, and our study indicates that separate consideration on each type of pre-miRNAs is more reasonable, especially in computational prediction. Besides, we develop a new criterion called mAMFE which shows robust discriminative power in distinguishing pre-miRNAs against other RNAs, thus can potentially serve as a discriminative feature in prediction of new pre-miRNAs.

Missing values in microarray data can significantly affect subsequent analysis, thus it is important to estimate these missing values accurately. In this paper, a sequential local least squares imputation (SLLSimpute) method is proposed to solve this problem. It estimates missing values sequentially from the gene containing the fewest missing values and partially utilizes these estimated values. In addition, an automatic parameter selection algorithm, which can generate an appropriate number of neighboring genes for each target gene, is presented for parameter estimation. Experimental results confirmed that SLLSimpute method exhibited better estimation ability compared with other currently used imputation methods.