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Baohong Zhang

Publications and source records attributed to Baohong Zhang.

At least 19 recordsLinked to original sources

SpliceHarmonization: an integrated method for identifying RNA splicing events in therapeutics for splicing modulation.

MOTIVATION: Splicing, a critical co-transcriptional process in eukaryotes, enhances transcriptome diversity by generating isoforms specific to cell types, tissues, or developmental stages. Recent advancements in splicing modulators have opened new avenues for targeting previously undruggable genes by inducing significant perturbations in splicing events. These developments underscore the need for comprehensive methods to accurately identify and compare splicing events. While several tools have been developed to detect local splice variants, inconsistencies across methods remain a significant challenge. To address this, we present SpliceHarmonization, an integrated approach that combines the strengths of rMATS, LeafCutter, and MAJIQ, enabling robust and reliable splicing analysis with event type annotations. RESULTS: In a comprehensive evaluation using diverse simulated datasets, SpliceHarmonization streamlined and standardized the outputs from three detection methods into a unified format, thereby improving splicing detection with event type annotation and outperforming individual methods. By integrating the outputs from rMATS, LeafCutter, and MAJIQ, our approach not only enhanced identification of a wide range of splicing events but also effectively mitigated method-specific discrepancies. This integration led to an accuracy exceeding 0.8 and a recall of up to 0.5, with an observed increase in AUC of up to 10%. Furthermore, SpliceHarmonization demonstrated high sensitivity in detecting low-abundance and complex splicing events, providing annotations including genomic coordinates and event type. AVAILABILITY AND IMPLEMENTATION: SpliceHarmonization is available at https://github.com/interactivereport/SpliceHarmonization.

RNA Splicing↗

N-Nitroso compounds produced in deer mouse (Peromyscus maniculatus) GI tracts following hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) exposure.

Given the potent carcinogenic effects of most N-nitroso compounds, the reductive transformation of the common explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) to a group of N-nitroso derivatives, hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (DNX), and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX) in the environment have caused concerns among the general public. Questions are arising about whether the same transformations also occur in mammals, and if true, to what extent. This study investigated the N-nitroso derivatives production in the deer mouse GI tract following RDX administration. Findings verified that such transformations do occur in the mammalian GI tract at notable levels: the average MNX concentrations in deer mice stomach were 85 microg/kg and 1318 microg/kg for exposure to 10mg/kg and 100mg/kg diet, respectively. DNX in stomach were 217 microg/kg for the 10mg/kg dose group and 498 microg/kg for the 100mg/kg dose group. Changes in other toxic endpoints including body weight gain, food consumption, organ weight, and behavior were also reported.

Animals↗

MicroRNAs and their regulatory roles in animals and plants.

microRNAs (miRNAs) are an abundant class of newly identified endogenous non-protein-coding small RNAs. They exist in animals, plants, and viruses, and play an important role in gene silencing. Translational repression, mRNA cleavage, and mRNA decay initiated by miRNA-directed deadenylation of targeted mRNAs are three mechanisms of miRNA-guided gene regulation at the post-transcriptional levels. Many miRNAs are highly conserved in animals and plants, suggesting that they play an essential function in plants and animals. Lots of investigations indicate that miRNAs are involved in multiple biological processes, including stem cell differentiation, organ development, phase change, signaling, disease, cancer, and response to biotic and abiotic environmental stresses. This review provides a general background and current advance on the discovery, history, biogenesis, genomics, mechanisms, and functions of miRNAs.

Animals↗

Characterizing viral microRNAs and its application on identifying new microRNAs in viruses.

MicroRNAs (miRNAs) are a newly identified class of non-protein-coding small RNAs, which play important roles in multiple biological and metabolic processes at the post-transcriptional level by directly cleaving targeted mRNAs or inhibiting translation. The lengths of viral miRNA precursors vary from 60 to 119 with an average of 79 nucleotides, which was smaller than observed for plant or animal miRNAs. Viral miRNAs are less conserved than plant and animal miRNAs, suggesting that viral miRNAs may evolve rapidly. Uracil nucleotide was highly dominant in the first position of 5' mature miRNAs. Viral miRNAs had high minimal folding free energy index (MFEI, 0.9 +/- 0.1). Based on these features and the well-known characteristics of miRNAs, 20 new potential miRNAs were identified in viruses by using expressed sequence tag (EST) analysis and genomic sequence survey (GSS) analysis. A better understanding of viral miRNA functions will be useful to design new approaches for treating viruses, especially those viruses that can induce human, animal, and plant diseases.

Base Composition↗

Computational identification of microRNAs and their targets.

MicroRNAs (miRNAs) are one class of newly identified riboregulators of gene expression in many eukaryotic organisms. They play important roles in multiple biological and metabolic processes, including developmental timing, signal transduction, cell maintenance and differentiation, diseases and cancers. miRNAs regulate gene expression at the posttranscriptional level by directly cleaving targeted mRNAs or repressing translation. Although the founding members of miRNAs were discovered by genetic screening approaches, experimental approaches were limited by their low efficiency, time consuming, and high cost. As an alternative, computational approaches were developed. Computational approaches for identifying miRNAs are based on the following major characteristics of miRNAs: hairpin-shaped secondary structures, high conservation for some miRNAs, and high minimal folding free energy index (MFEI). Computational approaches also play an important role in identifying miRNA targets. A majority of known miRNAs and their targets were identified by computational approaches. Several web-based or non-web-based computer software programs are publicly available for predicting miRNAs and their targets.

Animals↗

microRNAs as oncogenes and tumor suppressors.

microRNAs (miRNAs) are a new class of non-protein-coding, endogenous, small RNAs. They are important regulatory molecules in animals and plants. miRNA regulates gene expression by translational repression, mRNA cleavage, and mRNA decay initiated by miRNA-guided rapid deadenylation. Recent studies show that some miRNAs regulate cell proliferation and apoptosis processes that are important in cancer formation. By using multiple molecular techniques, which include Northern blot analysis, real-time PCR, miRNA microarray, up- or down-expression of specific miRNAs, it was found that several miRNAs were directly involved in human cancers, including lung, breast, brain, liver, colon cancer, and leukemia. In addition, some miRNAs may function as oncogenes or tumor suppressors. More than 50% of miRNA genes are located in cancer-associated genomic regions or in fragile sites, suggesting that miRNAs may play a more important role in the pathogenesis of a limited range of human cancers than previously thought. Overexpressed miRNAs in cancers, such as mir-17-92, may function as oncogenes and promote cancer development by negatively regulating tumor suppressor genes and/or genes that control cell differentiation or apoptosis. Underexpressed miRNAs in cancers, such as let-7, function as tumor suppressor genes and may inhibit cancers by regulating oncogenes and/or genes that control cell differentiation or apoptosis. miRNA expression profiles may become useful biomarkers for cancer diagnostics. In addition, miRNA therapy could be a powerful tool for cancer prevention and therapeutics.

Animals↗

Identification of 188 conserved maize microRNAs and their targets.

MicroRNAs (miRNAs) represent a newly identified class of non-protein-coding approximately 20nt small RNAs which play important roles in multiple biological processes by degrading targeted mRNAs or repressing mRNA translation. After searching a genomic survey sequence database using homologs and secondary structures, we found 188 maize miRNAs belonging to 29 miRNA families. Of the 188 maize miRNA genes, 28 (15%) were found in at least one EST. A total of 115 potential targets were identified for 26 of the miRNA families based on the fact that miRNAs exhibit perfect or nearly perfect complementarity with their target sequences. A majority of the targets are transcription factors which play important roles in maize development, including leaf, shoot, and root development. Additionally, these maize miRNAs are also involved in other cellular processes, such as signal transduction, stress response, sucrose and cellulose synthesis, and ubiquitin protein degradation pathway. Some of the newly identified miRNA targets may be unique to maize.

Base Sequence↗

Effects of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) metabolites on cricket (Acheta domesticus) survival and reproductive success.

The effect of two major hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) metabolites, hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX), on cricket (Acheta domesticus) survival and reproduction was studied. RDX metabolites did not have adverse effects on cricket survival, growth, and egg production. However, MNX and TNX did affect egg hatching. MNX and TNX were more toxic in spiked-sand than in topical tests. TNX was more toxic to egg than MNX. Developmental stage and exposure time affected hatching. After 30 days exposure to MNX or TNX, the EC20, EC50, and EC95 were 47, 128, and 247 microg/g for TNX, and 65, 140, and 253 microg/g for MNX in topical tests. The ECs for 20, 50, and 95 were 21, 52, and 99 microg/g for MNX, and 12, 48, and 97 microg/g for TNX in sand. No gross abnormalities in cricket nypmhs were observed in all experiments indicating that neither TNX or MNX is teratogenic in this assay.

Animals↗

Determination of N-nitroso derivatives of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in soils by pressurized liquid extraction and liquid chromatography-electrospray ionization mass spectrometry.

To aid in the evaluation of the potential toxicity of N-nitroso derivatives of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), we describe a pressurized liquid extraction (PLE) followed by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method for determination of RDX and its N-nitroso derivatives: hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (DNX), and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX) in soils. Sandy loam soil was spiked with RDX and its N-nitroso derivatives (MNX, DNX, and TNX). Acetonitrile was used as the PLE extraction solvent at 100 degrees C and 1500 psi for 15 min. Florisil was used to cleanup extracts following PLE. Instrumental analysis employed LC-ESI-MS, in which 1mM acetic acid was added to the mobile phase to facilitate formation of acetate adduct ions [M+CH(3)COO](-). The method detection limits (MDLs) for RDX, MNX, DNX, and TNX were 1.46, 1.46, 1.69, and 1.93 ng/g, respectively. High recovery (91.1-108.3%), good precision (RSD: 3.2-12.4%), and reproducibility were achieved. This method proved effective and was applied to monitor the reductive biotransformation of MNX in soils with the presence of earthworms (Eisenia fetida).

Chromatography, High Pressure Liquid↗

Assessment of pathogens and toxicants in New Orleans, LA following Hurricane Katrina.

Storm surge associated with Hurricane Katrina and the breach of levees protecting New Orleans, Louisiana allowed floodwaters from Lake Pontchartrain to inundate 80% of the city. Environmental samples were collected during September 16-18, 2005 to determine immediate human and wildlife health hazards from pathogens and toxicants in the floodwaters. Baseline information on potential long-term environmental damage resulting from contaminants in water and sediments pumped into Lake Pontchartrain was also collected. Concentrations of aldrin, arsenic, lead, and seven semivolatile organic compounds in sediments/soils exceeded one or more United States Environmental Protection Agency (USEPA) thresholds for human health soil screening levels and high priority bright line screening levels. High numbers of Aeromonas spp., pathogenic Vibrio spp., and other coliform bacteria were found in floodwater samples. Alligator and snake tissues did not contain excessive toxicant concentrations. Initial findings suggest numerous environmental contaminants are present in New Orleans and support the need for further evaluation of the extent of those threats.

Animals↗

Toxicity of the explosive metabolites hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX) and hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) to the earthworm Eisenia fetida.

Toxicity of hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX) to earthworm was evaluated. Both MNX and TNX had lethal and sublethal effects on earthworms. Exposure to MNX- or TNX-contaminated soil caused a significant concentration-dependent decrease in earthworm survival and growth. The lowest observed lethal concentration (LOLC) for both MNX and TNX was 100 and 200 mgkg(-1) soil dry weight in the sandy loam soil and in the silt loam soil, respectively. No earthworms survived for 14 days in MNX- or TNX-spiked soil at 500 mgkg(-1) soil dry weight. After 7 days exposure, the lowest observed effect concentration (LOEC) for earthworm growth was 50 mgkg(-1) soil dry weight for TNX and 100 mgkg(-1) soil dry weight for MNX in both soil types. The LC20 and LC50 for MNX in sandy loam soil were 114 and 262 mgkg(-1) and for TNX, they were 114 and 254 mgkg(-1) soil dry weight, respectively. The corresponding values for MNX and TNX in silt loam soil were 234 and 390 mgkg(-1) soil dry weight, respectively, and 200 and 362 mgkg(-1) soil dry weight, respectively. After 35 days exposure, earthworm growth was reduced 8-39% by TNX in sandy loam soil, whereas TNX only inhibited earthworm growth 5-18% at the same concentration range in silt loam soil. LC20 and LC50 for TNX were slightly lower than for MNX; this indicates that TNX was more toxic than MNX. No significant morphological or developmental abnormalities were observed in earthworms surviving exposure.

Animals↗

MicroRNA: a new player in stem cells.

microRNAs (miRNAs) are an abundant class of endogenous non-protein-coding small RNAs, which negatively regulate gene expression at the posttranscriptional level in many developmental and metabolic processes. miRNAs regulate a variety of biological processes, including developmental timing, signal transduction, tissue differentiation and maintenance, disease, and carcinogenesis. Emerging evidence demonstrates that miRNAs also play an essential role in stem cell self-renewal and differentiation. Some miRNAs are specifically expressed in stem cells, control stem cell self-renewal, and differentiation through negatively regulating the expression of certain key genes in stem cells.

Animals↗

Liquid chromatography/electrospray ionization tandem mass spectrometry analysis of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX).

A quantitative liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method was developed for the analysis of the explosive, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). In negative ionization mode, HMX forms an acetate adduct ion [M + CH(3)COO](-), m/z 355, in the presence of a small amount of acetic acid in the mobile phase. The ESI collision-induced dissociation (CID) spectrum of m/z 355 was acquired and the transitions m/z 355 --> 147 and m/z 355 --> 174 were chosen for the determination of HMX in samples. Using this quantification technique, the method detection limit was 1.57 microg/L and good linearity was achieved in the range 5-500 microg/L. This method will help to unambiguously analyze environmentally relevant concentrations of HMX.

Azocines↗

Conservation and divergence of plant microRNA genes.

MicroRNA (miRNA) is one class of newly identified, small, non-coding RNAs that play versatile and important roles in post-transcriptional gene regulation. All miRNAs have similar secondary hairpin structures; many of these are evolutionarily conserved. This suggests a powerful approach to predict the existence of new miRNA orthologs or homologs in other species. We developed a comprehensive strategy to identify new miRNA homologs by mining the repository of available ESTs. A total of 481 miRNAs, belonging to 37 miRNA families in 71 different plant species, were identified from more than 6 million EST sequences in plants. The potential targets of the EST-predicted miRNAs were also elucidated from the EST and protein databases, providing additional evidence for the real existence of these miRNAs in the given plant species. Some plant miRNAs were physically clustered together, suggesting that these miRNAs have similar gene expression patterns and are transcribed together as a polycistron, as observed among animal miRNAs. The uracil nucleotide is dominant in the first position of 5' mature miRNAs. Our results indicate that many miRNA families are evolutionarily conserved across all major lineages of plants, including mosses, gymnosperms, monocots and eudicots. Additionally, the number of miRNAs discovered was directly related to the number of available ESTs and not to evolutionary relatedness to Arabidopsis thaliana, indicating that miRNAs are conserved and little phylogenetic signal exists in the presence or absence of these miRNAs. Regulation of gene expression by miRNAs appears to have existed at the earliest stages of plant evolution and has been tightly constrained (functionally) for more than 425 million years.

Base Sequence↗

Plant microRNA: a small regulatory molecule with big impact.

MicroRNAs (miRNAs) are an abundant new class of non-coding approximately 20-24 nt small RNAs. To date, 872 miRNAs, belonging to 42 families, have been identified in 71 plant species by genetic screening, direct cloning after isolation of small RNAs, computational strategy, and expressed sequence tag (EST) analysis. Many plant miRNAs are evolutionarily conserved from species to species, some from angiosperms to mosses. miRNAs may originate from inverted duplications of target gene sequences in plants. Although miRNA precursors display high variability, their mature sequences display extensive sequence complementarity to their target mRNA sequences. miRNAs play important roles in plant post-transcriptional gene regulation by targeting mRNAs for cleavage or repressing translation. miRNAs are involved in plant development, signal transduction, protein degradation, response to environmental stress and pathogen invasion, and regulate their own biogenesis. miRNAs regulate the expression of many important genes; a majority of these genes are transcriptional factors.

Gene Expression Regulation, Plant↗

Evaluating the bioavailability of explosive metabolites, hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX), in soils using passive sampling devices.

The uptake kinetics of two major RDX (hexahydro-1,3,5-trinitro-1,3,5-triazacyclohexane) metabolites, hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX), into passive sampling devices (PSDs), and the ability of PSDs to serve as surrogates for evaluating bioavailability of MNX and TNX were investigated in laboratory sand and two soil types. The results indicate that MNX and TNX absorption into PSDs was best fitted with a polynomial curve model: y = ax2 + bx + c (y: amount of MNX or TNX absorbed into PSD; x: incubation time of PSDs in soil), with an excellent correlation coefficient (>0.95) for each type of soil amended with 10 mg/kg MNX or TNX. TNX was more readily absorbed by PSDs than MNX. Soil conditions, especially organic matter content, affected MNX and TNX uptake into PSDs. A relatively good correlation between MNX and TNX uptake into PSDs and uptake into earthworms was obtained in two types of natural soils (a silt loam soil from Nebraska and a sandy loam soil from Texas) and laboratory sand. A linear relationship between PSD uptake and earthworm uptake was observed. The correlation coefficients (r2) were > or = 0.82 for all test soils spiked with MNX or TNX. Organic matter content is one soil factor that affected the ratio of MNX or TNX uptake into earthworms versus uptake into PSDs. These data indicate that C18 PSDs may be used as a surrogate for soil organisms such as earthworms and provide a simple and easy chemical test for assessing the bioavailability of contaminants in soils.

Alkanes↗

Use of pressurized liquid extraction (PLE)/gas chromatography-electron capture detection (GC-ECD) for the determination of biodegradation intermediates of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in soils.

A rapid, sensitive, and reproducible method was developed for quantitative determination of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and its biodegradation intermediates, hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (DNX), and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX) in soils. RDX, MNX, DNX, or TNX was extracted from soil by pressurized liquid extraction (PLE), followed by cleanup using florisil. Instrumental analysis was performed using gas chromatography with electron capture detection (GC-ECD), which was highly sensitive to the parent explosive and its metabolites. The method detection limits (MDLs) were 0.243, 0.095, 0.138, and 0.057 ng/g for RDX, MNX, DNX, and TNX, respectively. The method gave high recovery (98-102%), good precision (0.22-5.14%), and reproducibility, and proved to be suitable for real world sample analysis.

Acetonitriles↗

Effects of perchlorate on earthworm (Eisenia fetida) survival and reproductive success.

The effects of perchlorate on earthworm, Eisenia fetida, survival and reproductive success were evaluated using three types of tests: dermal contact (filter paper), sand, and artificial soil. All studies utilized a range of perchlorate concentrations in order to simulate levels that are likely to occur in the environment under different scenarios (typical soil levels vs. spill levels). The OECD filter paper contact test involved exposing earthworms to the test compound on moist filter paper for 14 days to evaluate earthworm survival under a worst-case dermal exposure scenario. A similar test involved exposing the earthworms to perchlorate-contaminated sand, where earthworm survival decreased as concentration of perchlorate increased, with no worms surviving 14 days at the highest treatment concentrations (>2000 microg/g). However, the perchlorate concentrations that affected the survival of E. fetida are likely to occur only under extreme conditions (e.g. spills). The effect of perchlorate on the reproductive success (cocoon production) of E. fetida over a 4-week test period in artificial soil and a 3-week test period in sand was also examined. Production of cocoons was observed in soil containing up to 100 microg/g perchlorate, with no production in the uppermost treatment groups (1000 microg/g). Cocoon production was highest in the control group, although overall cocoon production appeared to be low. In contrast to the acute toxicity tests, perchlorate did affect earthworm reproduction at environmentally relevant soil concentrations. In addition, preliminary data suggest that cocoons produced under perchlorate contamination did not hatch as well as cocoons produced in control soil despite incubation of both sets of cocoons in clean soil or sand.

Animals↗