From Centrosymmetry to Noncentrosymmetry: Precise Structural Regulation and Characterization on ZnHPO3·2H2O Polymorphs.

Polymorphs of ZnHPO3·2H2O with centrosymmetry (Cmcm) and noncentrosymmetry (C2) structures were prepared by modified solution evaporation and seed-crystal-induced secondary nucleation methods. In Cmcm-ZnHPO3·2H2O, the zinc atoms are only octahedrally coordinated, while in C2-ZnHPO3·2H2O, they feature both tetrahedral and octahedral coordination. As a result, Cmcm-ZnHPO3·2H2O features a 2D layered structure with lattice water molecules located in the interlayer space, while C2-ZnHPO3·2H2O features a 3D electroneutral framework of tfa topology connected by Zn(1)O4, Zn(2)O6, and HPO3 units. The UV-visible diffuse reflectance spectra associated with Tauc's analyses give a direct bandgap of 4.24 and 4.33 eV for Cmcm-ZnHPO3·2H2O and C2-ZnHPO3·2H2O, respectively. Moreover, C2-ZnHPO3·2H2O exhibits a weak second harmonic generation (SHG) response and a moderate birefringence for phase matching, indicating its potential as a nonlinear optical material. Detailed dipole moment calculation and analysis confirmed that the SHG response mainly derived from the HPO3 pseudo-tetrahedra.

Two Indium Sulfate Tellurites: Centrosymmetric In2(SO4)(TeO3)(OH)2(H2O) and Non-centrosymmetric In3(SO4)(TeO3)2F3(H2O).

Two new indium sulfate tellurites, namely, In2(SO4)(TeO3)(OH)2(H2O) and In3(SO4)(TeO3)2F3(H2O), were synthesized by hydrothermal method in a one-pot reaction. Their pure phase yields have been successfully optimized to 76% and 21%, respectively. In2(SO4)(TeO3)(OH)2(H2O) crystallized in centrosymmetric (CS) space group P21/n, while In3(SO4)(TeO3)2F3(H2O) formed a non-centrosymmetric (NCS) and chiral space group P212121. The CS compound features a 2D layered structure composed of 2D indium oxide layers decorated by sulfate tetrahedra and tellurite groups. The NCS compound displays a 3D network consisting of indium tellurite layers bridged by sulfate tetrahedra. Powder second harmonic generation measurements disclosed that In3(SO4)(TeO3)2F3(H2O) exhibits a weak frequency-doubling efficiency about 11% of the commercial KDP. Its powder laser damage threshold quantity was estimated to be 79.6 MW/cm2, which is about 36 times that of AGS. The two samples present wide optical band gaps of 4.86 and 4.10 eV, respectively, which were determined by Te, In, and O atoms based on density functional theory calculations.

Novel glycylated sugar alcohols protect ESC-specific microRNAs from degradation in iPS cells.

Excessive accumulation of embryonic stem cell (ESC)-specific microRNAs occurs in both ESCs and induced pluripotent stem cells (iPSC); yet, the mechanism involved is unknown. In iPSCs, we for the first time found that novel glycylated sugar alcohols, particularly glycylglycerins, are tightly bound with ESC-specific microRNA precursors (pre-miRNA), such as pre-miR-302. Among these isolated glycylglycerins, we further identified that 1,3-diglycylglycerin and 1,2,3-triglycylglycerin are two major compounds bonded with negatively charged nucleic acids via electro-affinity and subsequently forming sugar-like coats in the hairpin-like double helix structures of pre-miRNAs. As a result, such glycylglycerin-formed coating serves as a protection layer against miRNA degradation. Moreover, we found that the pH value of iPSC cytosol determines the charges of these glycylglycerins. During iPSC differentiation, the cytosol pH is increased and hence neutralizes the charges of glycylglycerins, consequently leading to fast miRNA degradation. Therefore, the current findings not only explain how ESC-specific miRNAs are preserved and accumulated in iPSCs and ESCs but also demonstrate an important function of glycylglycerins in protecting the structural integrity of highly degradable miRNAs, providing a useful means for maintaining miRNA/siRNA function as well as developing the related RNA interference (RNAi) applications.

Gamma Irradiation as a Phytosanitary Treatment of Bactrocera tau (Diptera: Tephritidae) in Pumpkin Fruits.

The fruit fly Bactrocera tau (Walker) is an important quarantine pest that damages fruits and vegetables throughout Asian regions. Host commodities shipped from infested areas should undergo phytosanitary measures to reduce the risk of shipping viable flies. The dose-response tests with 1-d-old eggs and 3-, 5-, 7-, 8-d-old larvae were initiated to determine the most resistant stages in fruits, and the minimum dose for 99.9968% prevention of adult eclosion at 95% confidence level was validated in the confirmatory tests. The results showed that 1) the pupariation rate was not affected by gamma radiation except for eggs and first instars, while the percent of eclosion was reduced significantly in all instars at all radiation dose; 2) the tolerance to radiation increased with increasing age and developmental stage; 3) the estimated dose to 99.9968% preventing adult eclosion from late third instars was 70.9 Gy (95% CL: 65.6-78.2, probit model) and 71.8 Gy (95% CL: 63.0-87.3, logit model); and iv) in total, 107,135 late third instars cage infested in pumpkin fruits were irradiated at the target dose of 70 Gy (62.5-85.0, Gy measured), which resulted in no adult emergence in the two confirmatory tests. Therefore, a minimum dose of 85 and 72 Gy, which could prevent adult emergence at the efficacy of 99.9972 and 99.9938% at the 95% confidence level, respectively, can be recommended as a minimum dose for phytosanitary treatment of B. tau in any host fruits and vegetables under ambient atmospheres.

Removal of diclofenac sodium from water using a polyacrylonitrile mixed-matrix membrane embedded with MOF-808.

MOF-808, owing to the synergistic effect of its large surface area and surface charge matching, showed a diclofenac sodium (DCF) removal capacity as high as 630 mg g-1, and the ability to adsorb 436 mg g-1 DCF in two hours, outperforming many common Zr-MOFs under the same conditions. Importantly, a series of free-standing mixed-matrix membranes made by combining polyacrylonitrile with MOF-808 were fabricated and exhibited high efficiency of removing DCF from water via an easily accessible filtration method.

MicroRNA-mediated somatic cell reprogramming.

Since the first report of induced pluripotent stem cells (iPSCs) using somatic cell nuclear transfer (SCNT), much focus has been placed on iPSCs due to their great therapeutic potential for diseases such as abnormal development, degenerative disorders, and even cancers. Subsequently, Takahashi and Yamanaka took a novel approach by using four defined transcription factors to generate iPSCs in mice and human fibroblast cells. Scientists have since been trying to refine or develop better approaches to reprogramming, either by using different combinations of transcription factors or delivery methods. However, recent reports showed that the microRNA expression pattern plays a crucial role in somatic cell reprogramming and ectopic introduction of embryonic stem cell-specific microRNAs revert cells back to an ESC-like state, although, the exact mechanism underlying this effect remains unclear. This review describes recent work that has focused on microRNA-mediated approaches to somatic cell reprogramming as well as some of the pros and cons to these approaches and a possible mechanism of action. Based on the pivotal role of microRNAs in embryogenesis and somatic cell reprogramming, studies in this area must continue in order to gain a better understanding of the role of microRNAs in stem cells regulation and activity.

Regulation of somatic cell reprogramming through inducible mir-302 expression.

Global demethylation is required for early zygote development to establish stem cell pluripotency, yet our findings reiterate this epigenetic reprogramming event in somatic cells through ectopic introduction of mir-302 function. Here, we report that induced mir-302 expression beyond 1.3-fold of the concentration in human embryonic stem (hES) H1 and H9 cells led to reprogramming of human hair follicle cells (hHFCs) to induced pluripotent stem (iPS) cells. This reprogramming mechanism functioned through mir-302-targeted co-suppression of four epigenetic regulators, AOF2 (also known as KDM1 or LSD1), AOF1, MECP1-p66 and MECP2. Silencing AOF2 also caused DNMT1 deficiency and further enhanced global demethylation during somatic cell reprogramming (SCR) of hHFCs. Re-supplementing AOF2 in iPS cells disrupted such global demethylation and induced cell differentiation. Given that both hES and iPS cells highly express mir-302, our findings suggest a novel link between zygotic reprogramming and SCR, providing a regulatory mechanism responsible for global demethylation in both events. As the mechanism of conventional iPS cell induction methods remains largely unknown, understanding this microRNA (miRNA)-mediated SCR mechanism may shed light on the improvements of iPS cell generation.

A novel role of miR-302/367 in reprogramming.

Ever since the technique of coaxing ordinary skin cells into becoming pluripotent stem cells (iPSCs) has been developed, which have the potential to become any cell or tissue in the body, efforts were made to improve the approach because some major challenges. Increasing evidence suggests that several microRNAs (miRNAs) are involved in early embryonic development and embryonic stem cell formation, known as embryonic stem cell (ESC)-specific miRNAs, particularly the miR-302 family. We summarized here a novel approach to generate iPSCs by using miR-302 and its related miRNAs such as miR-367. The development of this miR-302/367-mediated iPSC (termed mirPSC) may provide tools to deal with the obstacles facing some current iPSC reprogramming methods. The mechanism by which miR-302/367 induce iPSC reprogramming is proposed.

[Bioinformatics Analysis of Core Genes and Key Pathways in Myelodysplastic Syndrome].

OBJECTIVE: To screen differentially expressed gene (DEG) related to myelodysplastic syndrome (MDS) based on Gene Expression Omnibus (GEO) database, and explore the core genes and pathogenesis of MDS by analyzing the biological functions and related signaling pathways of DEG. METHODS: The expression profiles of GSE4619, GSE19429, GSE58831 including MDS patients and normal controls were downloaded from GEO database. The gene expression analysis tool (GEO2R) of GEO database was used to screen DEG according to | log FC (fold change) |≥1 and P<0.01. David online database was used to annotate gene ontology function (GO). Metascape online database was used to enrich and analyze differential genes in Kyoto Encyclopedia of Genes and Genomes (KEGG). The protein-protein interaction network (PPI) was constructed by using STRING database. CytoHubba and Mcode plug-ins of Cytoscape were used to analyze the key gene clusters and hub genes. R language was used to diagnose hub genes and draw the ROC curve. GSEA enrichment analysis was performed on GSE19429 according to the expression of LEF1. RESULTS: A total of 74 co-DEG were identified, including 14 up-regulated genes and 60 down regulated genes. GO enrichment analysis indicated that BP of down regulated genes was mainly enriched in the transcription and regulation of RNA polymerase II promoter, negative regulation of cell proliferation, and immune response. CC of down regulated genes was mainly enriched in the nucleus, transcription factor complexes, and adhesion spots. MF was mainly enriched in protein binding, DNA binding, and ß-catenin binding. KEGG pathway was enriched in primary immunodeficiency, Hippo signaling pathway, cAMP signaling pathway, transcriptional mis-regulation in cancer and hematopoietic cell lineage. BP of up-regulated genes was mainly enriched in type I interferon signaling pathway and viral response. CC was mainly enriched in cytoplasm. MF was mainly enriched in RNA binding. Ten hub genes and three important gene clusters were screened by STRING database and Cytoscape software. The functions of the three key gene clusters were closely related to immune regulation. ROC analysis showed that the hub genes had a good diagnostic significance for MDS. GSEA analysis indicated that LEF1 may affect the normal function of hematopoietic stem cells by regulating inflammatory reaction, which further revealed the pathogenesis of MDS. CONCLUSION: Bioinformatics can effectively screen the core genes and key signaling pathways of MDS, which provides a new strategy for the diagnosis and treatment of MDS.

A Co-word Analysis of Selected Science Education Literature: Identifying Research Trends of Scaffolding in Two Decades (2000-2019).

This study aims to identify research trends of scaffolding in the field of science education. To this end, both descriptive analysis and co-word analysis were conducted to examine the selected articles published in the Social Science Citation Index journals from 2000 to 2019. A total of 637 papers were retrieved as research samples through rounds of searching in Web of Science database. Overall, this study reveals a growing trend of science educators' academic publications about scaffolding in the recent two decades. In these sample papers, from 1,487 non-repeated keywords, we extracted 286 author-defined keywords shared by at least two studies as a benchmark dictionary. A series of co-word analyses were then conducted based on the dictionary to reveal the underlying co-occurring relationships of the words in title and abstract of the sample papers. Results showed that "scaffolding," "support," and "design" were the top three most frequently used keywords during 2000 and 2019. Visualization of co-word networks in each 5-year period further helps clarify both educators' common research foci and relevant research trends. Derived discussion and potential research directions are also provided.

Electronegative very-low-density lipoprotein induces brain inflammation and cognitive dysfunction in mice.

Epidemiologic studies have indicated that dyslipidemia may facilitate the progression of cognitive dysfunction. We previously showed that patients with metabolic syndrome (MetS) had significantly higher plasma levels of electronegative very-low-density lipoprotein (VLDL) than did healthy controls. However, the effects of electronegative-VLDL on the brain and cognitive function remain unclear. In this study, VLDL isolated from healthy volunteers (nVLDL) or patients with MetS (metVLDL) was administered to mice by means of tail vein injection. Cognitive function was assessed by using the Y maze test, and plasma and brain tissues were analyzed. We found that mice injected with metVLDL but not nVLDL exhibited significant hippocampus CA3 neuronal cell loss and cognitive dysfunction. In mice injected with nVLDL, we observed mild glial cell activation in the medial prefrontal cortex (mPFC) and hippocampus CA3. However, in mice injected with metVLDL, plasma and brain TNF-α and Aß-42 levels and glial cell activation in the mPFC and whole hippocampus were higher than those in control mice. In conclusion, long-term exposure to metVLDL induced levels of TNF-α, Aß-42, and glial cells in the brain, contributing to the progression of cognitive dysfunction. Our findings suggest that electronegative-VLDL levels may represent a new therapeutic target for cognitive dysfunction.

Loss of mir-146a function in hormone-refractory prostate cancer.

The pattern of microRNA (miRNA) expression is associated with the degree of tumor cell differentiation in human prostate cancer. MiRNAs bind complementarily to either oncogenes or tumor suppressor genes, which are consequently silenced, resulting in alterations of tumorigenecity. We have detected eight down-regulated and three up-regulated known miRNAs in androgen-independent human prostate cancer cells compared to those in androgen-dependent cells, using miRNA microarray analyses. These identified miRNAs showed the same expression patterns in hormone-refractory prostate carcinomas (HRPC) compared to androgen-sensitive noncancerous prostate epithelium as determined by fluorescent in situ hybridization assays in human prostate cancer tissue arrays. One of the eight down-regulated miRNAs, mir-146a, was selected and constitutively expressed to examine its effects on suppression of prostate cancer transformation from androgen-dependent to -independent cells as determined by in vitro tumorigenecity assays. Transfection of mir-146a, which perpetually express the miRNA, suppressed >82% of the expression of the targeted protein-coding gene, ROCK1, in androgen-independent PC3 cells, consequently markedly reducing cell proliferation, invasion, and metastasis to human bone marrow endothelial cell monolayers. Given that ROCK1 is one of the key kinases for the activation of hyaluronan (HA)-mediated HRPC transformation in vivo and in PC3 cells, mir-146a may function as a tumor-suppressor gene in modulating HA/ROCK1-mediated tumorigenecity in androgen-dependent prostate cancer.

Mir-302 reprograms human skin cancer cells into a pluripotent ES-cell-like state.

Renewal of stem cells differs from cancer cell growth in self-controlled cell division. The mir-302 microRNA (miRNA) family (mir-302s) is expressed most abundantly in slow-growing human embryonic stem (ES) cells, and quickly decreases after cell differentiation and proliferation. Therefore, mir-302s was investigated as one of the key factors essential for maintenance of ES cell renewal and pluripotency in this study. The Pol-II-based intronic miRNA expression system was used to transgenically transfect the mir-302s into several human cancer cell lines. The mir-302-transfected cells, namely, miRNA-induced pluripotent stem (mirPS) cells, not only expressed many key ES cell markers, such as Oct3/4, SSEA-3, SSEA-4 ,Sox2, and Nanog, but also had a highly demethylated genome similar to a reprogrammed zygotic genome. Microarray analyses further revealed that genome-wide gene expression patterns between the mirPS and human ES H1 and H9 cells shared over 86% similarity. Using molecular guidance in vitro, these mirPS cells could differentiate into distinct tissue cell types, such as neuron-, chondrocyte-, fibroblast-, and spermatogonia-like primordial cells. Based on these findings, we conclude that mir-302s not only function to reprogram cancer cells into an ES-like pluripotent state but also to maintain this state under a feeder-free cultural condition, which may offer a great opportunity for therapeutic intervention.

MiR-302-Mediated Somatic Cell Reprogramming and Method for Generating Tumor-Free iPS Cells Using miR-302.

Human induced pluripotent stem cells (iPSCs) by four factors have the risks of teratoma formation and potential tumorigenicity. To overcome this major hurdle, we examined the mechanism(s) by which the cell cycle genes of embryonic cells were regulated. Naturally occurring embryonic stem cells (ESCs) possess two unique stemness properties: pluripotent differentiation into all cell types and self-renewal with no risk of tumor formation. Despite overwhelming reports describing iPSC pluripotency, there have been no observations of tumor prevention mechanism that suppresses tumor formation similar to that in naturally occurring ESCs. The ESC-specific microRNA (miRNA), miR-302, regulates human iPSC tumorigenicity through co-suppression of both cyclin E-CDK2 and cyclin D-CDK4/6 cell cycle pathways during G1-S phase transition. MiR-302 also silenced BMI-1, a cancer stem cell marker gene, to promote the expression of two senescence-associated tumor suppressor genes, p16Ink4a and p14/p19Arf. Together, the combinatory effect of reducing G1-S cell cycle transition and increasing p16/p14(p19) expression resulted in a relatively attenuated cell cycle rate similar to that of 2-to-8-cell-stage embryonic cells in early mammalian zygotes (20-24 h/cycle), as compared to the fast proliferation rate of iPSCs induced by four defined factors Oct4-Sox2-Klf4-c-Myc (12-16 h/cycle). In addition to the prevention of stem cell tumorigenicity, the mechanism underlying miR-302-mediated iPSCs also includes the initiation of global genomic DNA methylation, activation of ESC-specific gene expression, and inhibition of developmental signaling. Overall, we have established an effective protocol to express the intronic miR-302 cluster, according to its own natural biogenesis mechanism to generate tumor-free iPSCs for use in biology and therapy.

Intron-mediated RNA interference and microRNA biogenesis.

Nearly 97% of the human genome is non-coding DNA, and introns occupy most of it around the gene-coding regions. Numerous intronic sequences have been recently found to encode microRNAs, which are responsible for RNA-mediated gene silencing through RNA interference (RNAi)-like pathways. microRNAs (miRNAs), small single-stranded regulatory RNAs capable of interfering with intracellular messenger RNAs (mRNAs) that contain either complete or partial complementarity, are useful for the design of new therapies against cancer polymorphism and viral mutation. This flexible characteristic is different from double-stranded siRNAs (small interfering RNAs) because a much more rigid complementarity is required for siRNA-induced RNAi gene silencing. miRNAs were firstly discovered in Caenorhabditis elegans as native RNA fragments that modulate a wide range of genetic regulatory pathways during embryonic development. Currently, varieties of miRNAs are widely reported in plants, animals and even microbes. Intronic microRNA is a new class of miRNAs derived from the processing of gene introns. The intronic miRNAs differ uniquely from previously described intergenic miRNAs in the requirement of type II RNA polymerases (Pol-II) and spliceosomal components for their biogenesis. Several kinds of intronic miRNAs have been identified in C. elegans, mouse and human cells; however, neither function nor application has been reported. Here, we show for the first time that intron-derived miRNAs are able to induce RNA interference in not only human and mouse cells but also zebrafishes, chicken embryos and adult mice, demonstrating the evolutionary preservation of the intron-mediated gene silencing through miRNA functionality in cell and in vivo. These findings suggest an intracellular miRNA-mediated gene regulatory system, fine-tuning the degradation of protein-coding messenger RNAs.

catena-Poly[bis{mu-dihydrogen [(5-carboxypentylimino)dimethylene]diphosphonato-kappa2O:O'}cadmium(II)].

The title compound, [Cd(C(8)H(18)NO(8)P(2))(2)](n), synthesized by hydrothermal methods, exhibits a layered structure in which the Cd(II) ion, occupying a centre of symmetry, is coordinated by six O atoms from four phosphonate ligands. The crosslinkage of CdO(6) octahedra by bridging phosphonate ligands results in a cadmium(II) phosphonate layer. Within the layer, there exists a 16-membered ring incorporating four -Cd-O-P-O- linkages. The uncoordinated carboxyl group of the ligand is oriented so that it penetrates the adjacent layer, taking part in hydrogen bonding to two uncoordinated phosphonate O atoms to form a CO(2)H/HO(2)P motif.

The microRNA and the perspectives of miR-302.

MiRNAs are naturally occurring, small, non-coding RNA molecules that post-transcriptionally regulate the expression of a large number of genes involved in various biological processes, either through mRNA degradation or through translation inhibition. MiRNAs play important roles in many aspects of physiology and pathology throughout the body, particularly in cancer, which have made miRNAs attractive tools and targets for translational research. The types of non-coding RNAs, biogenesis of miRNAs, circulating miRNAs, and direct delivery of miRNA were briefly reviewed. As a case of point, the role and perspective of miR-302, a family of ES-specific miRNA, on cancer, iPSCs, heart disease were presented.

Androgen receptor regulates CD168 expression and signaling in prostate cancer.

Dysregulation of the androgen receptor (AR) and its signaling in the prostate often occurs during normal aging or after androgen ablation, consequently leading to the development of hormone-refractory prostate cancer (HRPC). Hyaluronan (HA) plays an important role in this transformation of androgen-independent cancer. Previous studies have shown that activation of the receptor for hyaluronan-mediated motility, CD168, was correlated with the Gleason's score, cancer stage, transformation and metastasis in >90% of HRPC patients. However, the relationship between loss of AR dependency and HA-mediated CD168 signaling remains unclear. We report here that AR regulates normal CD168 expression and its downstream signaling in androgen-dependent (AD) prostatic epithelial cell lines. Furthermore, we observed that the concurrent treatments of HA and dihydrotestosterone (DHT), a native androgen, significantly promoted the tumorigenicity of AD prostate cancer cell lines, which showed elevated rates of cell proliferation, invasion and metastasis to the human bone marrow endothelial cell layer. Inhibition of CD168 downstream Rho-activated protein kinases completely prevented this type of tumorigenicity. These findings suggest that the interaction of androgen and AR is essential for regulating HA-mediated cancer progression via the CD168/ROCK signal transduction pathway and also indicate that the loss of AR regulation not only causes CD168 overexpression but it also activates HA-mediated CD168 signaling in malignant cancer progression and metastasis of HRPC.

Intron-mediated RNA interference and microRNA (miRNA).

MicroRNAs (miRNAs) are small single-stranded regulatory RNAs capable of interfering with messenger RNAs (mRNAs) through complete or partial complementarities. Partial complementarity gives miRNAs a flexibility which is useful for construction of new therapies against cancer polymorphisms and viral mutations. Varieties of miRNAs have been reported in diverse species; and they are believed to induce RNA interference (RNAi), a post-transcriptional gene silencing mechanism. Recently, many intronic sequences have been shown to encode microRNAs. Intronic miRNA, a new class of miRNAs, is derived from introns by RNA splicing and Dicer processing, and it differs uniquely from previously described intergenic miRNA in that intronic miRNAs require type II RNA polymerases (Pol-II) and spliceosomal components for their biogenesis. Several kinds of intronic miRNAs have been identified; however, their functions and applications have not been reported. Here, we show for the first time that intron-derived miRNAs are able to induce RNA interference in many cells demonstrating the evolutionary preservation of this post-transcriptional regulatory system in vivo.

The microRNA (miRNA): overview of the RNA genes that modulate gene function.

MicroRNAs (miRNAs), widely distributed, small regulatory RNA genes, target both messenger RNA (mRNA) degradation and suppression of protein translation based on sequence complementarity between the miRNA and its targeted mRNA. Different names have been used to describe various types of miRNA. During evolution, RNA retroviruses or transgenes invaded the eukaryotic genome and inserted in the non-coding regions of DNA, conceivably acting as transposon-like jumping genes, providing defense from viral invasion and fine-tuning of gene expression as a secondary level of gene modulation in eukaryotes. When a transposon is inserted in the intron, it becomes an intronic miRNA, taking advantage of the protein synthesis machinery, i.e., mRNA transcription and splicing, as a means for processing and maturation. Recently, miRNAs have been found to play an important, but not life-threatening, role in embryonic development. They might play a pivotal role in diverse biological systems in various organisms, facilitating a quick response and accurate plotting of body physiology and structures. Based on these unique properties, man-made intronic miRNAs have been developed for in vitro evaluation of gene function, in vivo gene therapy and generation of transgenic animal models. The biogenesis and identification of miRNAs, potential applications, and future directions for research are presented, hopefully providing a guideline for further miRNA and gene function studies.