Fluorescent probes for formaldehyde based on formaldehyde-promoted C-N cleavage of azanyl carbamates.

Formaldehyde (FA) is an endogenous one-carbon metabolite and an environmental pollutant and carcinogen. Elevated FA levels are associated with many diseases. Methods for the convenient and in situ detection of FA levels are of great significance for understanding FA's biofunctions and signalling pathways. Herein, the NAP-FAP2 series of fluorescent probes for FA detection were developed based on FA-promoted C-N cleavage of 3-nitrophenylazanyl N-arylcarbamate via FA-induced intramolecularity, where the aryl group is the fluorophore 1,8-naphthalimide-4-yl. The 3-nitrophenylazanyl containing reactive group also functions as a fluorescence quenching group via a photo-induced electron transfer mechanism to generate turn-on fluorescence response upon reaction with FA. The probes were applied to explore FA level changes in erastin-induced ferroptosis, and it was found that the FA level increases intracellularly, but not in the endoplasmic reticulum, suggesting that the FA level increases in ferroptosis are not derived from lipid peroxidation.

Cultivating the scientific research ability of undergraduate students in teaching of genetics.

The classroom is the main venue for undergraduate teaching. It is worth pondering how to cultivate undergraduate's research ability in classroom teaching. Here we introduce the practices and experiences in teaching reform in genetics for training the research quality of undergraduate students from six aspects: (1) constructing the framework for curriculum framework systematicaly, (2) using the teaching content to reflect research progress, (3) explaining knowledge points with research activities, (4) explaining the scientific principles and experiments with PPT animation, (5) improving English reading ability through bilingual teaching, and (6) testing students' analysing ability through examination. These reforms stimulate undergraduate students' enthusiasm for learning, cultivate their ability to find, analyze and solve scientific problems, and improve their English reading and literature reviewing capacity, which lay a foundation for them to enter the field of scientific research.

Understanding the cellular and molecular mechanisms of dominant and recessive inheritance in genetics course.

In Mendellian genetics, the dominance and recessiveness are used to describe the functional relationship between two alleles of one gene in a heterozygote. The allele which constitutes a phenotypical character over the other is named dominant and the one functionally masked is called recessive. The definitions thereby led to the creation of Mendel's laws on segregation and independent assortment and subsequent classic genetics. The discrimination of dominance and recessiveness originally is a requirement for Mendel's logical reasoning, but now it should be explained by cellular and molecular principles in the modern genetics. To answer the question raised by students of how the dominance and recessiveness are controlled, we reviewed the recent articles and tried to summarize the cellular and molecular basis of dominant and recessive inheritance. Clearly, understanding the essences of dominant and recessive inheritance requires us to know the dissimilarity of the alleles and their products (RNA and/or proteins), and the way of their function in cells. The alleles spatio-temporally play different roles on offering cells, tissues or organs with discernible phenotypes, namely dominant or recessive. Here, we discuss the changes of allele dominance and recessiveness at the cellular and molecular levels based on the variation of gene structure, gene regulation, function and types of gene products, in order to make students understand gene mutation and function more comprehensively and concretely.

[The genetic control of mouse coat color and its applications in genetics teaching].

Mice are the most commonly used mammalian model. The coat colors of mice are typical Mendelian traits, which have various colors such as white, black, yellow and agouti. The inheritance of mouse coat color is usually stated as an example only in teaching the knowledge of recessive lethal alleles. After searched the related literatures and summarized the molecular mechanisms of mouse coat color inheritance, we further expanded the application of this example into the introduction of the basic concepts of alleles and Mendelian laws, demonstration of the gene structure and function, regulation of gene expression, gene interaction, epigenetic modification, quantitative genetics, as well as evolutionary genetics. By running this example through the whole genetics-teaching lectures, we help the student to form a systemic and developmental view of genetic analysis. At the same time, this teaching approach not only highlights the advancement and integrity of genetics, but also results in a good teaching effect on inspiring the students' interest and attracting students' attention.

An exploration for research-oriented teaching model in biology teaching.

Training innovative talents, as one of the major aims for Chinese universities, needs to reform the traditional teaching methods. The research-oriented teaching method has been introduced and its connotation and significance for Chinese university teaching have been discussed for years. However, few practical teaching methods for routine class teaching were proposed. In this paper, a comprehensive and concrete research-oriented teaching model with contents of reference value and evaluation method for class teaching was proposed based on the current teacher-guiding teaching model in China. We proposed that the research-oriented teaching model should include at least seven aspects on: (1) telling the scientific history for the skills to find out scientific questions; (2) replaying the experiments for the skills to solve scientific problems; (3) analyzing experimental data for learning how to draw a conclusion; (4) designing virtual experiments for learning how to construct a proposal; (5) teaching the lesson as the detectives solve the crime for learning the logic in scientific exploration; (6) guiding students how to read and consult the relative references; (7) teaching students differently according to their aptitude and learning ability. In addition, we also discussed how to evaluate the effects of the research-oriented teaching model in examination.

An anthracenecarboximide-guanidine fluorescent probe for selective detection of glyoxals under weak acidic conditions.

An anthracenecarboximide-guanidine based turn-on fluorescent probe ANC-DCP-1 for selective detection of glyoxals (methylglyoxal and glyoxal, GOS) over formaldehyde under weak acidic conditions around pH 6.0 was reported. The probe showed great potential in studying relative GOS levels in weak acidic biological fluids such as in urine for diabetic diagnosis and prognosis, and also found application in the food industry such as for fast unique manuka factor (UMF) scale determination of Manuka honey.

Muscles are barely required for the patterning and cell dynamics in axolotl limb regeneration.

Regeneration of a complex appendage structure such as limb requires upstream and downstream coordination of multiple types of cells. Given type of cell may sit at higher upstream position to control the activities of other cells. Muscles are one of the major cell masses in limbs. However, the subtle functional relationship between muscle and other cells in vertebrate complex tissue regeneration are still not well established. Here, we use Pax7 mutant axolotls, in which the limb muscle is developmentally lost, to investigate limb regeneration in the absence of skeletal muscle. We find that the pattern of regenerated limbs is relative normal in Pax7 mutants compared to the controls, but the joint is malformed in the Pax7 mutants. Lack of muscles do not affect the early regeneration responses, specifically the recruitment of macrophages to the wound, as well as the proliferation of fibroblasts, another major population in limbs. Furthermore, using single cell RNA-sequencing, we show that, other than muscle lineage that is mostly missing in Pax7 mutants, the composition and the status of other cell types in completely regenerated limbs of Pax7 mutants are similar to that in the controls. Our study reveals skeletal muscle is barely required for the guidance of other cells, as well the patterning in complex tissue regeneration in axolotls, and provides refined views of the roles of muscle cell in vertebrate appendage regeneration.

A PET-based fluorescent probe for monitoring labile Fe(II) pools in macrophage activations and ferroptosis.

A fluorescent probe (COU-LIP-1) for monitoring labile Fe(II) pools (LIP) with high selectivity and sensitivity was developed utilizing coumarin 343 as the fluorophore and 3-nitrophenylazanyl ester as both the reactive group and the fluorescence quenching group. Fe(II)-induced reductive cleavage of the N-O bond results in a turn-on response via a photo-induced photon transfer (PET) mechanism. The probe was applied for monitoring labile iron(II) changes in M1 and M2a macrophage activations and also erastin-induced ferroptosis, providing a powerful tool for selectively sensing LIP under both physiological and stressed conditions.

Dimethyl Fumarate Combined With Vemurafenib Enhances Anti-Melanoma Efficacy via Inhibiting the Hippo/YAP, NRF2-ARE, and AKT/mTOR/ERK Pathways in A375 Melanoma Cells.

Melanoma is a deadly form of skin cancer with high rates of resistance to traditional chemotherapy and radiotherapy. BRAF inhibitors (BRAFi) can achieve initial efficacy when used to treat melanoma patients, but drug resistance and relapse are common, emphasizing the need for new therapeutic strategies. Herein, we reported that combination of dimethyl fumarate (DMF) and vemurafenib (Vem) inhibited melanoma cell proliferation more significantly and induced more cell death than single agent did both in vitro and in vivo. DMF/Vem treatment induced cell death through inhibiting the expression and transcriptional activity of NRF2 thereby resulting in more reactive oxygen species (ROS) and via inhibiting the expression of YAP, a key downstream effector of Hippo pathway. DMF/Vem treatment also reduced phosphorylation of AKT, 4EBP1, P70S6K and ERK in AKT/mTOR/ERK signaling pathways. RNA-seq analysis revealed that DMF/Vem treatment specifically suppressed 4561 genes which belong to dozens of cell signaling pathways. These results indicated that DMF/Vem treatment manifested an enhanced antitumor efficacy through inhibiting multiple cell signaling pathways, and thus would be a novel promising therapeutic approach targeted for melanoma.

Molecular cloning and characterization of Izumo1 gene from sheep and cashmere goat reveal alternative splicing.

We cloned the cDNA and genomic DNA encoding for Izumo1 of cashmere goat (Capra hircus) and sheep (Ovis aries). Analysis of 4.6 kb Izumo1 genomic sequences in sheep and goat revealed a canonical open reading frame (ORF) of 963 bp spliced by eight exons. Sheep and goat Izumo1 genes share >99% identity at both DNA and protein levels and are also highly homologous to the orthologues in cattle, mouse, rat and human. Extensive cloning and analysis of Izumo1 cDNA revealed three (del 69, del 182 and del 217) and two (del 69 and ins 30) alternative splicing isoforms in goat and sheep, respectively. All of the isoforms are derived from splicing at typical GT-AG sites leading to partial or complete truncation of the immunoglobulin (Ig)-like domain. Bioinformatics analysis showed that caprine and ovine Izumo1 proteins share similar structure with their murine orthologue. There are a signal peptide at the N-terminus (1-22 aa), a transmembrane domain at the C-terminus (302-319 aa), and an extracellular Ig-like region in the middle (161-252 aa) with a putative N-linked glycosylation site (N(205)-N-S). Alignment of Izumo1 protein sequences among 15 mammalian species displayed several highly conserved regions, including LDC and YRC motifs with cysteine residues for potential disulfide bridge formation, CPNKCG motif upstream of the Ig-like domain, GLTDYSFYRVW motif upstream of the putative N-linked glycosylation site, and a number of scattered cysteine residues. These distinctive features are very informative to pinpoint the important gene motifs and functions. The C-terminal regions, however, are more variable across species. Izumo1 cDNA sequences of goat, sheep, and cow were found to be largely homologous, and the molecular phylogenetic analysis is consistent with their morphological taxonomy. This implies the Izumo1 gene evolves from the same ancestor, and the mechanism of sperm-egg fusion in mammals may be under the same principle in which Izumo1 plays an important role.

Zhenbao pill attenuates hydrogen peroxide-induced apoptosis by inhibiting autophagy in human umbilical vein endothelial cells.

ETHNOPHARMACOLOGICAL RELEVANCE: The Zhenbao pill (ZBP) is composed of 29 traditional Chinese medicines and has been proven to exhibit a valid therapeutic effect in nervous system diseases, such as stroke and hemiplegia sequelae. AIM OF THE STUDY: Whether ZBP has a protective effect on vascular endothelial cells remains unknown. In this study, we established hydrogen peroxide (H2O2)-induced oxidative injury in human umbilical vein endothelial cells (HUVECs) as an in vitro model to investigate the pharmacological effects of ZBP. MATERIALS AND METHODS: Following the intragastric administration of ZBP (0.25, 0.5, and 1 g/kg for seven days) in rats, drug-containing serum was obtained and cultivated with HUVECs before H2O2 treatment. The viability of HUVECs in the presence of H2O2 was measured by Cell Counting Kit-8 assay, lactate dehydrogenase assay, and flow cytometry. Furthermore, we estimated the effects of ZBP on the production of reactive oxygen species (ROS) and mitochondrial membrane potential (MMP). Autophagic puncta were detected using a fluorescence microscope. Western blotting and real-time polymerase chain reaction were used to detect the expression levels of several genes associated with apoptosis and autophagy. RESULTS: Drug-containing serum separated from rats at 1 h after intragastric administration of ZBP (0.5 g/kg) significantly offered a protective effect to HUVECs and reduced cell apoptosis rates. Meanwhile, ZBP-containing serum also repressed ROS production induced by H2O2 exposure and maintained MMP. Further investigation revealed that ZBP-containing serum effectively reduced the accumulation of autophagic puncta. ZBP-mediated inhibition on cell autophagy was found to contribute to ameliorating cell apoptosis. Western blotting also confirmed that ZBP maintained AKT and mTOR phosphorylation and antagonized the imbalance of BCL2/BAX, thereby protecting cells from apoptosis. CONCLUSION: Taken together, our data indicate that ZBP inhibits ROS production, mitochondrial damage, cell autophagy, and cell apoptosis. ZBP can offer protection to vascular endothelial cells against oxidative injury through the antagonism of apoptosis and autophagy. Thus, this study enhances the understanding of the therapeutic effects and mechanisms of ZBP in the process of recovery from myocardial and cerebral ischemic stroke.

An "AND"-logic-gate-based fluorescent probe with dual reactive sites for monitoring extracellular methylglyoxal level changes of activated macrophages.

An "AND"-logic-gate-based fluorescent probe NAP-DCP-4 with dual reactive sites is reported, which has improved selectivity for methylglyoxal over glyoxal, featuring formaldehyde-enhanced methylglyoxal detection and irreversible and reversible turn-on fluorescence responses at different excitation wavelengths. Its cell-impermeability enables facile monitoring of extracellular methylglyoxal level changes in the supernatant of activated macrophages.

Positive selection signals of hepatitis B virus and their association with disease stages and viral genotypes.

The hepatitis B virus (HBV) is a global health problem that causes different types of liver diseases. The high mutation rate of HBV, which results from a lack of proofreading activity of the viral polymerase, leads to the actively adaptive evolution of mutant strains under various selection pressures. This study focuses on the positive selection signals in the whole HBV genome and the association of these selection signals with the disease stages and/or viral genotypes. A total of 486 complete HBV genomes from HBV-infected individuals of different illness categories (i.e., acute, chronic, and severe hepatitis) were analyzed. To obtain a panoramic view of the selection signals, codon-based maximum likelihood analysis, three-dimensional (3D) mapping, and allele frequency comparison were conducted on genotypes B and C HBV from subjects with different stages of hepatitis. A total of 95 selected codons were resolved, and a significantly higher number of positive selection signatures were found in the chronic and severe hepatitis groups compared with the acute groups. Many of the selected codons were associated with either a unique disease stage or a specific genotype. The conservation analysis of the selection signals in the viral core protein (HBcAg) illustrated the occurrence of selected codons in the highly diversified regions. The allele-frequency-based analysis identified eight additional nucleotide substitutions, and the frequencies of these mutations were found to increase with disease progression. Moreover, we found that three substitutions, including A1762T, G1764A, and A2739C, were nearly fixed. The mapping of all of the selected codons and nucleotide substitutions to the functional domains of the viral proteins suggested that more than 60% of the mutations were subject to selection forces from host immune surveillance, antiviral therapy, and replication fitness.

[Cloning, prokaryotic expression of rat RVLG and preparation of mouse anti-RVLG polyclonal antibody].

In order to identify rat ovarian germ cells, we expressed and purified rat RVLG protein in Escherichia coli cells and prepared a mouse anti-rat RVLG polyclonal antibody. The rat RVLG cDNA was obtained from rat testicle tissue by RT-PCR and was cloned into the vector pMD19-T. Sequence analysis proves that the cloned RVLG cDNA fragment was 60 bp longer than that released in the GenBank (NM_001077647), resulting from an alternative splicing of the RVLG pre-mRNA. The RVLG cDNA was double digested with the restriction endonucleases BamH I and EcoR I, and then was extracted from gel and inserted into the prokaryotic expression vector pGEX-4T-1. The recombinant expression plasmid pGEX-RVLG was verified for successful construction and then was transformed into Escherichia coli BL21(DE3) for induction to express the GST-RVLG fusion protein by IPTG. The GST-RVLG fusion protein was expressed in Escherichia coli BL21 (DE3) at a high level which accounts for more than 10% of the total bacterial cellular protein. The purified RVLG protein was used as an antigen to immunize KM mouse for the production of polyclonal antibody in ascetic fluid followed by celiacly injecting the mouse with S180 cells. The mouse anti-rat RVLG antibody was analyzed by ELISA, Western blotting and immunohistochemistry for its specificity and titer. The antibody could recognize RVLG protein specifically and its titer was about 1:20 000. These results confirm that the mouse anti-rat RVLG polyclonal antibody with high affinity and specificity has been prepared successfully, and lay a foundation for our ongoing research on the specific expression of RVLG in rat ovary.

Effects of SHIP-1 on MMP2 secretion and invasion of SR3Y1 cells.

SHIP-1 is an SH2 domain containing inositol-5-phosphatase that appears to be a negative regulator of hematopoiesis. To the potential effects of SHIP-1 on MMP2 secretion and migration of cancer cells, three murine SHIP-1 mutants were made: DeltaSH2-SHIP-1, DeltaPtase-SHIP-1, DeltaCter-SHIP-1. These mutant forms were subcloned as well as the wild type (WT) of murine SHIP-1 cDNA were subcloned into pcDNA3 expression vector, then transfected into and overexpressed SHIP-1 and its mutants in a Src-transformed 3Y1 cell line (SR3Y1). The results showed that overexpression of wild type of SHIP-1 does not affect the MMP2 secretion in both SR3Y1 and 3Y1 cells, but can induce MMP9 secretion, while either WT SHIP-1, the SH2 domain, phosphatase domain, or C terminus deletion mutants could significantly block the MMP2 and MMP9 secretion in SR3Y1 cells and suppress cell invasion ability. The results confirmed SHIP-1 as a negative regulator for cell migration and invasion in transformed cells, and implied that it may function through each of its three domains.