Progress in rolling circle amplification in biological detection / 生物工程学报

Rolling circle amplification is a rapid, sensitive and isothermal single-stranded DNA amplification technique that can be used with staining or probes to amplify the detection signal. This technology has been widely used in biological detection and other aspects. The present paper introduces how to design rolling circle amplification, summarize its application in the detection of pathogens, nucleic acid tumor markers, proteins, biological small biomolecules, and viruses in recent years and prospects for future development.

Possible Role of Single Stranded DNA Binding Protein 3 on Skin Hydration by Regulating Epidermal Differentiation

BACKGROUND: Skin hydration is a common problem both in elderly and young people as dry skin may cause irritation, dermatological disorders, and wrinkles. While both genetic and environmental factors seem to influence skin hydration, thorough genetic studies on skin hydration have not yet been conducted. OBJECTIVE: We used a genome-wide association study (GWAS) to explore the genetic elements underlying skin hydration by regulating epidermal differentiation and skin barrier function. METHODS: A GWAS was conducted to investigate the genetic factors influencing skin hydration in 100 Korean females along with molecular studies of genes in human epidermal keratinocytes for functional study in vitro. RESULTS: Among several single nucleotide polymorphisms identified in GWAS, we focused on Single Stranded DNA Binding Protein 3 (SSBP3) which is associated with DNA replication and DNA damage repair. To better understand the role of SSBP3 in skin cells, we introduced a calcium-induced differentiation keratinocyte culture system model and found that SSBP3 was upregulated in keratinocytes in a differentiation dependent manner. When SSBP3 was overexpressed using a recombinant adenovirus, the expression of differentiation-related genes such as loricrin and involucrin was markedly increased. CONCLUSION: Taken together, our results suggest that genetic variants in the intronic region of SSBP3 could be determinants in skin hydration of Korean females. SSBP3 represents a new candidate gene to evaluate the molecular basis of the hydration ability in individuals.

Real-time PCR: an appropriate approach to confirm ssDNA generation from PCR product in SELEX process

Background: Aptamers are single stranded DNA [ssDNA] or RNA molecules. The potential of aptamers for binding to the different targets has made them be widely used as the preferred diagnostic and therapeutic tools. DNA aptamers present several advantages over the RNA oligonucleotides due to their higher stability, easier selection, and production. Selection of DNA aptamers which is facilitated through a systematic evolution of ligand by exponential enrichment [SELEX] method is much dependent on the successful conversion of double stranded DNA [dsDNA] to ssDNA

Objective: There are different methods available for ssDNA generation. While visualization of ssDNA is limited to the gelbased method, the method is not applicable in the initial rounds of SELEX due to more than 1015 different sequences. This study was designed to evaluate the efficiency of another technique for confirming the ssDNA generation in comparison to the polyacrylamide electrophoresis [PAGE] analysis

Materials and Methods: Real-time PCR was employed in the present study for PCR amplification of the initial library that was followed by enzymatic digestion of the dsDNA. Subsequently melting curve analysis was carried out to evaluate ssDNA generation from dsDNA. Moreover, PAGE analysis was performed and the results were compared with the melt curve analysis

Results: The melt curves, revealed dsDNA conversion to the ssDNA based on a significant reduction of Tm from 73.8 to 41.5 [degree]C. Applying PAGE analysis, it was not effectively feasible to show ssDNA generation from the corresponding initial dsDNA library, while, it was efficient enough to confirm ssDNA generation in accordance with the increasing the number of SELEX rounds

Conclusion: The present study has proven the applicability of the real-time PCR as a suitable confirmatory technique for validating ssDNA generation in the DNA aptamer selection process for the initial library preparation

A colorimetric method for vascular endothelial growth factor detection based on aptamer and magnetic beads / 南方医科大学学报

<p><b>OBJECTIVE</b>To develop a novel colorimetric method for detecting the tumor biomarker vascular endothelial growth factor (VEGF) based on aptamer and magnetic beads.</p><p><b>METHODS</b>The capture aptamer was hybridized to urease functionalized single-stranded DNA (ssDNA) and immobilize on the surface of magnetic beads by specific biotin-avidin binding. In the presence of VEGF, aptamers bound to VEGF to form a specific stem-loop structure to release the urease functionalized ssDNA. After separation, the supernatant was transferred to a tube and urea and phenol red were added. Urease hydrolyzed urea to produce ammonia to cause an increase of the pH value and a color change of phenol red. The results were inspected with either the naked eyes or by a UV spectrophotometer.</p><p><b>RESULTS</b>Under optimized conditions, the detection system showed a good linear relationship for VEGF detection in the range of 0.1 to 10 pmol/L with a detection limit as low as 0.06 pmol/L. The results of VEGF detection in the serum of patients with lung cancer were consistent with those using an ELISA Kit. The results of examination of 10 serum samples with this aptamer-based method and ELISA kit showed that the accuracy of this method was 90%.</p><p><b>CONCLUSION</b>This aptamer-based system provides an simple and convenient method for VEGF detection with a high sensitivity and selectivity.</p>

Compiling Multicopy Single-Stranded DNA Sequences from Bacterial Genome Sequences

A retron is a bacterial retroelement that encodes an RNA gene and a reverse transcriptase (RT). The former, once transcribed, works as a template primer for reverse transcription by the latter. The resulting DNA is covalently linked to the upstream part of the RNA; this chimera is called multicopy single-stranded DNA (msDNA), which is extrachromosomal DNA found in many bacterial species. Based on the conserved features in the eight known msDNA sequences, we developed a detection method and applied it to scan National Center for Biotechnology Information (NCBI) RefSeq bacterial genome sequences. Among 16,844 bacterial sequences possessing a retron-type RT domain, we identified 48 unique types of msDNA. Currently, the biological role of msDNA is not well understood. Our work will be a useful tool in studying the distribution, evolution, and physiological role of msDNA.

Preparation of a novel AAV-ITR gene expression mini vector in Sf9 insect cells via baculovirus / 生物工程学报

AAV-ITR gene expression mini vector is a double-strand or single-strand DNA that only contains inverted terminal repeats of adeno-associated virus, cis-elements and gene of interest and does not contain any other foreign DNA sequences. We prepared Bac-ITR-EGFP and Bac-inrep. Spodoptera frugiperda cells were infected with Bac-ITR-EGFP (P3) and Bac-inrep (P3). Up to 100 μg of AAV-ITR-EGFP gene expression mini vectors were extracted from 2 x 10(7) cells of Sf9 72 h after infection. The gel electrophoresis analysis shows that most forms of AAV-ITR-EGFP gene expression mini vector were monomer and dimer. The mini vector expression efficacy was examined in vitro with HEK 293T cells. The EGFP expression was observed at 24 h after transfection, and the positive ratio reached 65% at 48 h after transfection.

DNA aptamer selection in vitro for determining ketamine by FluMag-SELEX / 法医学杂志

OBJECTIVE@#To select specific DNA aptamer for determining ketamine by FluMag-SELEX.@*METHODS@#Based on magnetic beads with tosyl surface modification as solid carrier and ketamine as target, a random ssDNA library with total length of 78 bp in vitro was compounded. After 13 rounds screening, DNA cloning and sequencing were done. Primary and secondary, structures were analyzed. The affinity, specificity and Kd values of selected aptamer were measured by monitoring the fluorescence intensity.@*RESULTS@#Two ssDNA aptamers (Apt#4 and Apt#8) were successfully selected with high and specific abilities to bind ketamine as target with Kd value of 0.59 and 0.66 μmol/L. The prediction of secondary structure was main stem-loop and G-tetramer. The stem was the basis of stability of aptamer's structure. And loop and G-tetramer was the key of specific binding of ketamine.@*CONCLUSION@#FluMag-SELEX can greatly improve the selection efficiency of the aptamer, obtain the ketamine-binding DNA aptamer, and develop a new method for rapid detection of ketamine.

Gene expression of AAV-ITR ssDNA mini vector in skeletal muscle of mice / 生物工程学报

AAV-ITR single strand DNA mini vector (AAV-ITR ssDNA mini vector) is a novel gene expression vector based on AAV-ITR. We have shown efficient gene expression of AAV-ITR ssDNA mini vector in HEK 293T. Here, we studied the efficacy of gene expression of AAV-ITR ssDNA mini vector in vivo. We injected the skeletal muscle of ICR mice separately with equal molars of AAV-ITR ssDNA mini vector, ITR mutated AAV-ITR single strand DNA mini vector (AAV-ITRmm ssDNA mutant vector), AAV-ITR dsDNA and pUC57-minivector-GFP, combined with TurboFect. Florescence microscope analysis of skeletal muscle section shows that AAV-ITR ssDNA mini vector had higher expression efficiency and longer expression period. We extracted DNA from the muscle three months after injection and quantified three vectors by Real-time PCR. RT-PCR analysis shows that there were highest copy numbers of AAV-ITR ssDNA mini vector existing in muscle. Stable existing of AAV- TR ssDNA mini vector in muscle could be the molecular basis of long term gene expression of the vector. The results suggest that AAV-ITR ssDNA mini vector might be a promising vector for gene therapy.

Single-molecule detection and characterization of DNA replication based on DNA origami / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate single-molecule detection and characterization of DNA replication.</p><p><b>METHODS</b>Single-stranded DNA (ssDNA) as the template of DNA replication was attached to DNA origami by a hybridization reaction based on the complementary base-pairing principle. DNA replication catalyzed by E.coli DNA polymerase I Klenow Fragment (KF) was detected using atomic force microscopy (AFM). The height variations between the ssDNA and the double-stranded DNA (dsDNA), the distribution of KF during DNA replication and biotin-streptavidin (BA) complexes on the DNA strand after replication were detected. Agarose gel electrophoresis was employed to analyze the changes in the DNA after replication.</p><p><b>RESULTS</b>The designed ssDNA could be anchored on the target positions of over 50% of the DNA origami. The KF was capable of binding to the ssDNA fixed on DNA origami and performing its catalytic activities, and was finally dissociated from the DNA after replication. The height of DNA strand increased by about 0.7 nm after replication. The addition of streptavidin also resulted in an DNA height increase to about 4.9 nm due to the formation of BA complexes on the biotinylated dsDNA. The resulting dsDNA and BA complex were subsequently confirmed by agarose gel electrophoresis.</p><p><b>CONCLUSIONS</b>The combination of AFM and DNA origami allows detection and characterization of DNA replication at the single molecule level, and this approach provides better insights into the mechanism of DNA polymerase and the factors affecting DNA replication.</p>

Expression and purification of four single-stranded DNA-binding proteins and their binding on HCV RNA / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>Express and purify four single-stranded DNA-binding (SSB) proteins, and evaluate the binding of SSB proteins on HCV RNA.</p><p><b>METHODS</b>The expression plasmids of four SSB proteins were conducted, termed TTH, SSOB, KOD and BL21, respectively. The BL21 (DE3) was transformed by the expression plasmid of TTH, Transetta (DE3) were transformed by the expression plasmid of SSOB, KOD and BL21, then protein expression was induced with IPTG, the expression products were analysised by SDS-PAGE. To evaluate the binding of SSB on HCV RNA, RNA-SSB protein complexes were applied to a 1.2% TAE agarose gel.</p><p><b>RESULTS</b>Suitable competent cells were transformed with the expression plasmids, induced by IPTG. SSB proteins were purified by affinity chromatography, to visualize their purity all SSB proteins were applied to SDS-PAGE analysis. All four proteins showed single clear bands. We have successfully obtained the SSB protein expression plasmid, expressed and purified SSB protein. TAE agarose gel electrophoresis was used to confirm SSB protein-RNA binding activity. The each of SSB-RNA complex migrated more slowly than the sole RNA, which suggested SSB protein could specifically bind to RNA.</p><p><b>CONCLUSIONS</b>We have expressed and purified four SSB proteins, and for the first time found that SSB protein can bind HCV RNA. Our results may provide a basis for future studies of the novel functions of SSB proteins on RNA.</p>

In vitro selection of single strand deoxyribonucleic acid aptamers binding to cells from patients with acute myeloblastic leukemia / 中南大学学报(医学版)

OBJECTIVE@#To screen aptamers binding CD33+/CD34- cells from patients with acute myeloblastic leukemia M2 subtype (AML-M2).@*METHODS@#CD33+/CD34- cells from patients with AML-M2 were taken as targeted cells, CD33+/ CD34- cells from normal people were taken as anti-selecting cells, and aptamers in the single strand deoxyribonucleic acid (ssDNA) library were then selected repeatedly by cell-systematic evolution of ligands by exponential enrichment (C-SELEX) technology, and amplified by polymerase chain reaction (PCR) to generate sub-ssDNA library. During the experiment, PCR amplification with fluorescently labeled primer and flow cytometry were performed to analyze the aptamers'enrichment of sub-library, and the final round product of the sub-ssDNA library was cloned. After the sequencing, the primary and secondary structures of the aptamers were analyzed.@*RESULTS@#Electrophoresis indicated that the product of PCR amplification for each round subssDNA library was able to see a clear DNA band in the agarose gel. After 13 rounds of screening, the fluorescence intensity of the sub-ssDNA library binding the cells ranged from 2.14% to 51.12%, reaching a steady state at the 13th round. A total of 30 clones were selected and sequenced, 22 of which contained 1 of the 4 conserved sequences of AAGTA, TATCT, AGATG and AAATT in their primary structure, but the remained eight aptamers contained none of the conserved sequence. Secondary structure analysis indicated that four stem-loops and loop simulation convex structures existed in the aptamers.@*CONCLUSION@#C-SELEX technology can be used to screen the aptamers binding primary cells from patients with leukemia. The aptamers selected from the CD33+/CD34- cells from the patients of AML-M2 subtype might be used for the diagnosis and treatment for leukemia.

Screening and characterization of aptamers of Cepsilon3-Cepsilon4 protein / 药学学报

In order to obtain nucleotides aptamers bind to IgE, 80 bp nucleotides single-stranded DNA library containing 40 random nucleotides was designed and synthesized. Oligonucleotides that bind to human Cepsilon3-Cepsilon4 protein were isolated from ssDNA pools by the systematic evolution of ligands by exponential enrichment (SELEX) method using nitrocellulose filters as screening medium. Through the optimization of critical PCR and asymmetric PCR parameters including annealing temperature, cycles, and molar ratios of target protein and ssDNA etc, a suitable screening system was established. The aptamers of Cepsilon3-Cepsilon4 protein with high affinity and high specificity were identified by ELISA with biotin-streptavidin-horseradish peroxidase system, and its primary sequence and second structure were analyzed by DNAMAN package and DNA folding sever after being cloned and sequenced. Moreover, target protein was bound to one aptamer and another aptamer modified with biotion together forming a sandwich-like complex, which was captured in microwell to detect IgE concentration using the optimal combination in the sandwich method named enzyme-linked aptamers sorption assay (ELASA). The method could be used for the quantitative detection of human IgE, and whose sensitivity reached to 120 ng x mL(-1).

Most Highly Cytokinergic IgEs Have Polyreactivity to Autoantigens

PURPOSE: Monomeric IgE molecules, when bound to the high-affinity receptor, exhibit a vast heterogeneity in their ability to induce survival promotion and cytokine production in mast cells. At one end of this spectrum, highly cytokinergic (HC) IgEs can induce potent survival promotion, degranulation, cytokine production, migration, etc., whereas at the other end, poorly cytokinergic (PC) IgEs can do so inefficiently. In this study, we investigated whether IgEs recognize autoantigens and whether IgEs' binding of autoantigens correlates with difference s in HC versus PC properties. METHODS: Enzyme-linked immunosorbent assays were performed to test whether IgEs bind antigens. Histamine-releasing factor in human sera was quantified by western blotting. Cultured mast cells derived from human cord blood were used to test the effects of human sera on cytokine production. RESULTS: Most (7/8) of mouse monoclonal HC IgEs exhibited polyreactivity to double-stranded DNA (dsDNA), single-stranded DNA (ssDNA), beta-galactosidase, thyroglobulin and/or histamine-releasing factor. By contrast, mouse PC IgEs failed to react with these antigens. A human monoclonal HC IgE also showed polyreactivity to histamine-releasing factor, dsDNA and ssDNA. Interestingly, sera from atopic dermatitis patients showed increased reactivity to ssDNA and beta-galactosidase and increased levels of histamine-releasing factor. Some atopic dermatitis patients, but not healthy individuals, had substantial serum levels of HRF-reactive IgE. Sera from atopic dermatitis patients with high titers of DNA-reactive IgE could induce several fold more IL-8 secretion in human mast cells than sera from healthy individuals. CONCLUSIONS: The results show that most HC, but not PC, IgEs exhibit polyreactivity to autoantigens, supporting the autoimmune mechanism in the pathogenesis of atopic dermatitis.

Selection and identification of specific-binding peptides for cancer stem cell surface marker CD133 / 南方医科大学学报

<p><b>OBJECTIVE</b>To select the peptides that specifically bind human cancer stem cell surface marker CD133 from the Ph.D.-7>(TM) phage peptide library.</p><p><b>METHODS</b>With a biotinylated extracellular fragment of human cancer stem cell surface marker CD133 as the target protein, the CD133 high-affinity peptides were screened from the phage peptide library by liquid phase panning. The clones with high-binding force with human CD133 were then identified by sandwich ELISA and their single-stranded DNA was extracted to test the specificity by competitive ELISA. The amino acid sequences of the selected peptides derived from the phage DNA sequences were synthesized after sequence alignment analysis, and their capacity of binding with colorectal carcinoma cells was assessed by immunofluorescence technique.</p><p><b>RESULTS</b>After 4 rounds of liquid phase selection, the phages capable of specific binding with human CD133 were effectively enriched, with an enrichment ratio of 388 times compared to that at the fourth and first rounds. Thirteen out of the 20 clones from the fourth round of panning were identified as positive clones, among which 11 had identical amino acid sequence of TISWPPR, and 2 had the sequence of STTKLAL, and the former sequence showed a stronger binding specificity to CD133.</p><p><b>CONCLUSION</b>We have successfully obtained a peptide that specifically binds human CD133 from the Ph.D.-7(TM) phage peptide library, demonstrating the feasibility of screening small molecule high-affinity polypeptides from phage peptide library by liquid-phase panning.</p>

Drosophila RecQ5 is required for efficient SSA repair and suppression of LOH in vivo

RecQ5 in mammalian cells has been suggested to suppress inappropriate homologous recombination. However, the specific pathway(s) in which it is involved and the underlining mechanism(s) remain poorly understood. We took advantage of genetic tools in Drosophila to investigate how Drosophila RecQ5 (dRecQ5) functions in vivo in homologous recombination-mediated double strand break (DSB) repair. We generated null alleles of dRecQ5 using the targeted recombination technique. The mutant animals are homozygous viable, but with growth retardation during development. The mutants are sensitive to both exogenous DSB-inducing treatment, such as gamma-irradiation, and endogenously induced double strand breaks (DSBs) by I-Sce I endonuclease. In the absence of dRecQ5, single strand annealing (SSA)-mediated DSB repair is compromised with compensatory increases in either inter-homologous gene conversion, or non-homologous end joining (NHEJ) when inter-chromosomal homologous sequence is unavailable. Loss of function of dRecQ5 also leads to genome instability in loss of heterozygosity (LOH) assays. Together, our data demonstrate that dRecQ5 functions in SSA-mediated DSB repair to achieve its full efficiency and in suppression of LOH in Drosophila.

Detection of alphaB-crystallin mRNA using Single-stranded DNA Probe in Oligodendrocytes of the Developing Chick Retina / 체질인류학회지

In situ hybridization (ISH) using single-stranded DNA probe (ssDNA probe) is a useful method for observing the specific transcripts in cells, since it is convenient to prepare probe which is specific and sensitive. In this study, ssDNA probe for detection of alphaB-crystallin (aBC) mRNA, transcript of a heat shock protein, was prepared and aBC mRNA-expressed cells were spatiotemporally observed in the retina of the developing chick embryos. Single-stranded antisense probe produced by reverse transcription and polymerase chain reaction was identified as a specific probe for aBC mRNA in comparison to negative control using sense probe and immunohistochemistry for aBC protein. In the ISH experiment, aBC mRNA was expressed only in the peripapillary glial cells which are a specific cell type located in the avian retina adjacent to the optic nerve at E12 and E14 retinas. At E16, a small number of aBC mRNA-expressed cells were identified in the nerve fiber layer (NFL) of the retina. At E18, aBC mRNA-expressed cells were observed in the ganglion cell layer (GCL) as well as the NFL. At E20, the number of aBC mRNA-expressed cells was increased in the GCL and the NFL. Based on the same localization of nkx2.2 immunoreactive cells and aBC mRNA-expressed cells, aBC mRNA-expressed cells were identified as oligodendrocytes. These results indicate that ssDNA probe for aBC mRNA detection is very useful tool for oligodendrocyte research such as distribution, migration and differentiation of the cells.

Single-stranded megaprimer splicing through OE-PCR: Construction of full-length Aspergillus niger arginase cDNA.

A useful variant of PCR technique was devised to generate full-length Aspergillus niger arginase cDNA for expression. Briefly, a 450 bp amplicon was first constructed through overlap extension PCR (OE-PCR) by splicing in a 101 nucleotide long single-stranded megaprimer, facilitated by inclusion of an additional, shorter forward primer in the reaction. The amplicon was suitably cloned into pBlueScript to obtain pArg440 and the insert sequenced. The full-length arginase cDNA was subsequently assembled in pArg440 and moved into pET23a for heterologous expression. An interesting feature of this strategy was not to stoichiometrically incorporate the oligonucleotide megaprimer, but use it only as an early template. This OE-PCR strategy to utilize long single-stranded megaprimer may prove handy in terms of efficiency, yield and sequence choice.

Trends in development of self-complementary adeno-associated virus vector / 生物工程学报

Numerous studies and clinical trials have demonstrated the efficacy of recombinant adeno-associated virus gene delivery vectors. However, prior to expression, it is necessary to convert the single-stranded DNA genome into double-stranded DNA, which hinders the efficiency of these vectors. We can entirely circumvent this step through the use of self-complementary recombinant adeno-associated virus vector (scrAAV). ScrAAV packages an inverted repeat genome that can fold into double-stranded DNA without the requirement for DNA synthesis or base-pairing between multiple vector genomes. By using scrAAV, we could increase expression efficiency and reduce immune response caused by vectors themselves. Therefore, it is a promising vector for gene therapy. So far, it has been used in the treatment of hepatic diseases, central nervous system diseases, and eye diseases. It has also been used in the modifications of stem cells and as vectors for siRNA/miRNA and ribozymes. In this review, we focused on the preparation, expression and location of scrAAV both in vitro and in vivo. We mainly introduced the recent progress of scrAAV based therapy of Hemophilia B, in order to elucidate the potential and prospects of scrAAV in gene therapy.

Research of 10-23 DNAZyme inhibit the expression of eIF4E genes / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To explore the possibility of 10-23DNAzyme becoming a new gene therapy for laryngeal carcinoma treatment at the cell level.@*METHOD@#Thiosthorothioate 10-23DNAzyme specific to eIF4E gene mRNA 1059 was designed and synthesized, and its inhibition effects on the expression of eIF4E gene in Hep-2 cells were observed.@*RESULT@#The expression of eIF4E gene was remarkable depressed after Hep-2 cells was transfected by DNAzyme. The level of inhibiting eIF4E in hep-2 cells transfected by DNAzyme was lower than that by only lipofectamine 2000 transfected and Hep-2.@*CONCLUSION@#The expression of eIF4E gene in Hep-2 cells 10-23DNAzyme can be highly blocked. It is a specific and effective gene therapeutic means.

Clinicopathological and biological features of micrometastasis in early gastric cancers / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the clinicopathological and biological features of micrometastasis in early gastric cancers.</p><p><b>METHODS</b>Eleven cases of early gastric cancer with micrometastasis (micrometastatic, MM group) and 46 cases of early gastric cancer with lymph node metastasis (control group) were included in the study. Immunochemical staining of ssDNA, bcl-2, p53, E-cadherin, Ki-67, CD34 was performed. The superficial lesions, invasive fronts and lymph nodes were examined in both groups.</p><p><b>RESULTS</b>Positive rate of ssDNA at the superficial lesions in MM group was higher than that in control group. In MM group the positive rate of ssDNA in micrometastasis was higher than that at invasive fronts and in lymph nodes. Positive rate of bcl-2 at the superficial lesions in micrometastasis was higher than that at invasive fronts and lymph nodes. Positive rate of c-myc at the superficial lesions in MM group was higher than that in control group. Positive rate of E-cadherin and the percentage of microvascular areas at the lymph nodes in MM group was lower than those in control group. Proliferative ability of cancer cells at superficial lesions and lymph nodes in MM group was lower than those in control group. Lymph nodes <3 mm in micrometastasis accounted for 27.3%.</p><p><b>CONCLUSION</b>The pathological and biological features of micrometastasis in early gastric cancer show low positive rate of ssDNA, E-cadherin, Ki-67 and low percentage of microvascular areas at the lymph nodes.</p>