Transcriptional regulatory network during axonal regeneration of dorsal root ganglion neurons:laser-capture microdissection and deep sequencing

The key regulators and regeneration-associated genes involved in axonal regeneration of neurons after injury have not been clarified.In high-throughput sequencing,various factors influence the final sequencing results,including the number and size of cells,the depth of sequencing,and the method of cell separation.There is still a lack of research on the detailed molecular expression profile during the regeneration of dorsal root ganglion neuron axon.In this study,we performed lase r-capture microdissection coupled with RNA sequencing on dorsal root ganglion neurons at 0,3,6,and 12 hours and 1,3,and 7 days after sciatic nerve crush in rats.We identified three stages after dorsal root ganglion injury:early(3-12 hours),pre-regeneration(1 day),and regeneration(3-7 days).Gene expression patterns and related function enrichment res ults showed that one module of genes was highly related to axonal regeneration.We verified the up-regulation of activating transcription factor 3(Atf3),Kruppel like factor 6(Klf6),AT-rich inte raction domain 5A(Arid5α),CAMP responsive element modulator(Crem),and FOS like 1,AP-1 transcription factor Subunit(Fosl1) in dorsal root ganglion neurons after injury.Suppressing these transcription factors(Crem,Arid5o,Fosl1 and Klf6) reduced axonal regrowth in vitro.As the hub transcription factor,Atf3 showed higher expression and activity at the preregeneration and regeneration stages.G protein-coupled estrogen receptor 1(Gper1),inte rleukin 12a(Il12α),estrogen receptor 1(ESR1),and interleukin 6(IL6) may be upstream factors that trigger the activation of Atf3 during the repair of axon injury in the early stage.Our study presents the detailed molecular expression profile during axonal regeneration of dorsal root ganglion neurons after peripheral nerve injury.These findings may provide reference for the clinical screening of molecular targets for the treatment of peripheral nerve injury.

Studies on Contamination of Cytoplasm DNA and Its Control in Plant Chromosone Microdissection

染色体微切割和微克隆已成为复杂基因组研究的有效途径 ,但是操作过程中的核外DNA的污染一直是令人担心的问题。通过研究植物染色体微切割 (微分离 )和微切割的染色体DNA扩增过程中细胞质DNA的污染问题 ,表明目前常用的植物染色体微切割过程中 ,细胞质DNA的污染几乎难以避免 ,并提出了一个改进的降低细胞质DNA污染的方法 ,对如何控制细胞质DNA的污染进行了详细的讨论。

Microdissection of Haynaldia villosa Telosome 6VS and Cloning of Species-specific DNA Sequences

The material T240_6 derived from SC 2 young embryo of the combination CA9211/RW15 (6D/6V alien substitution) was telosomic substitution line of 6VS identified by GISH (genomic in situ hybridization) analysis. The 6VS was microdissected with a needle and transferred into a 0.5 mL Ep tube. In the 'single tube', all the subsequence steps were conducted. After two round of LA (Linker adaptor)_PCR amplification, the size of PCR bands ranged from 100 to 3 000 bp, with predominate bands 600-1 500 bp. The products were confirmed by Southern blotting analysis using Haynaldia villosa (L.) Schur. genomic DNA labeled with 32 P as probe. The PCR products were purified and ligated into clone vector-pGEM_T easy vector. Then, the plasmids were transformed into competence E. coli JM109 with cool CaCl 2. It was estimated that there were more than 17 000 white clones in the library. The size of insert fragments distributed from 100-1 500 bp, with average of 600 bp. Using H. villosa genomic DNA as probe, dot blotting results showed that 37% clones displayed strong and medium positive signals, and 63% clones had faint or no signals. It is demonstrated that there were about 37% repeat sequence clones and 67% single/unique sequence clones in the library. Eight H. villosa_specific clones were screened from the library, and two clones pHVMK22 and pHVMK134 were used for RFLP analysis and sequencing. Both of them were H. villosa specific clones. The pHVMK22 was a unique sequence clone, and the pHVMK134 was a repeat sequence clone. When the pHVMK22 was used as a probe for Southern hybridization, all the powdery mildew resistance materials showed a special band of 2 kb, while all the susceptible ones not. The pHVMK22 may be applied to detect the existence of Pm21.

Laser Capture Microdissection Combined with RNA in vitro Linear Amplification Detecting the Relevant Genes of Bladder Cancer

Objective： Laser capture microdisection has become indispensable to the analysis of the difference of gene expression between human bladder transitional cell and bladder transitional cell carcinoma （BTCC）. However, to obtain sufficient RNA from laser-capture microdissected cells is quite difficult. The study was designed to determinc a feasible technical routine to isolate transitional cells from bladder membrane, separate carcinoma cclls from stromal cells and to amplify the RNA isolated from laser-capture microdissected cells. Methods： Bladder transitional cell were obtained from frozen sections of bladder membrane applying LCM, by the same token, BTCC cells from frozen sections of BTCC tissue. Then RNA was extracted and linearly amplified in vitro. The expression levels of β-actin in primary total RNA and amplified RNA were detected using RT-PCR. Results： That RNA integrity was good after LCM was confirmed by control experiment Ⅰ; By control experiment Ⅱ, the correlation between the number of LCM-shooting and RNA quantity undcr arranged conditions was preliminarily confirmed. About 0.5-2.5kb RNA fragments were obtained after RNA amplification and β-actin levels were integral. Conclusion： Laser capture microdissection combined with RNA linear amplification in vitro can be successfully applied to obtain pure objective cells for research. The integrity of the amplified RNA is good and can be employed in further research.

Comparison of gene expression profiles between primary tumor and metastatic lesions in gastric cancer patients using laser microdissection and cDNA microarray

AIM. To study the differential gene expression profiles of target cells in primary gastric cancer and its metastatic lymph nodes using laser microdissection （LMD） in combination with cDNA microarray. METHODS： Normal gastric tissue samples from 30 healthy individuals, 36 cancer tissue samples from primary gastric carcinoma and lymph node metastasis tissue samples from 58 patients during gastric cancer resection were obtained using LMD in combination with cDNA microarray independently. After P27-based amplification, aRNA from 36 of 58 patients （group 1） with lymph node metastasis and metastatic tissue specimens from the remaining 22 patients （group 2） were applied to cDNA microarray. Semiquantitative reverse transcriptase polymerase chain reaction （RT-PCR） and imrnunohistochemical assay verified the results of microarray in group 2 and further identified genes differentially expressed in the progression of gastric cancer. RESULTS： The expression of 10 genes was up-regulated while the expression of 15 genes was down-regulated in 22 gastric carcinoma samples compared with that of genes in the normal controls. The results were confirmed at the level of mRNA and protein, and suggested that four genes （OPCML, RNASE1, YES1 and ACK1） could play a key role in the tumorigenesis and metastasis of gastric cancer. The expression pattern of 3 genes （OPCML, RNASE1 and YES1） was similar to tumor suppressor genes. For example, the expression level of these genes was the highest in normal gastric epithelium, which was decreased in primary carcinoma, and further decreased in metastatic lymph nodes. On the contrary, the expression pattern of gene ACK1 was similar to that of oncogene. Four genes were further identified as differentially expressed genes in the majority of the cases in the progression of gastric cancer. CONCLUSION： LMD in combination with cDNA microaro ray provides a unique support foe the identification of early expression profiles of differential genes and the expression pattern of 3 genes （OPCML, RNASE1 and YES1） associated with the progression of gastric cancer. Further study is needed to reveal the molecular mechanism of lymph node metastasis in patients with gastric cancer.

No relationship between biopsy sites near the main testicular vessels or rete testis and successful sperm retrieval using conventional or microdissection biopsies in 220 non-obstructive azoospermic men

In 220 consecutive patients with non-obstructive azoospermia, sperm retrieval was attempted by a combination of conventional and microdissection testicular sperm extraction （TESE）. For sperm retrieval, 2-3 conventional biopsies were performed followed by a microdissection TESE in cases of negative conventional biopsies. During the surgery, the vasculature of the testis was assessed using the operative microscope, and the location of positive biopsies was registered in relation to the blood supply. The overall sperm retrieval rate was 58.2%. From the initial conventional biopsies, sperm could be retrieved in 46.8% of the patients. With microdissection TESE, sperm could be retrieved from an additional 11.4% of the patients. The further use of microdissection TESE improved the sperm retrieval rate significantly （P=0.017）. No significant accumulation of positive biopsies was found towards the rete testis or the main testicular vessels.

Gene expression profiling of gastric cancer by microarray combined with laser capture microdissection

AIM： To examine the gene expression profile of gastric cancer （GC） by combination of laser capture microdissection （LCM） and microarray and to correlate the profiling with histological subtypes. METHODS： Using LCM, pure cancer cells were procured from 45 cancerous tissues. After procurement of about 5 000 cells, total RNA was extracted and the quality of RNA was determined before further amplification and hybridization. One microgram of amplified RNA was converted to cDNA and hybridized to cDNA microarray. RESULTS： Among 45 cases, only 21 were qualified for their RNAs. A total of 62 arrays were performed. These included 42 arrays for cancer （21 cases with dyeswab duplication） and 20 arrays for non-tumorous cells （10 cases with dye-swab duplication） with universal reference. Analyzed data showed 504 genes were differentially expressed and could distinguish cancerous and non-cancerous groups with more than 99% accuracy. Of the 504 genes, trefoil factors 1, 2, and 3 were in the list and their expression patterns were consistent with previous reports. Immunohistochemical staining of trefoil factor 1 was also consistent with the array data. Analyses of the tumor group with these 504 genes showed that there were 3 subgroups of GC that did not correspond to any current classification system, including Lauren＇s dassification. CONCLUSION： By using LCM, linear amplification of RNA, and cDNA microarray, we have identified a panel of genes that have the power to discriminate between GC and non-cancer groups. The new molecular classification and the identified novel genes in gastric carcinogenesis deserve further investigations to elucidate their clinicopathological significance.

Identification of differentially expressed genes of primary spermatocyte against round spermatid isolated from human testis using the laser capture microdissection technique

The method of laser capture microdissection (LCM) combined with suppressive subtractive hybridization (SSH) was developed to isolate specific germ cells from human testis sections and to identify the genes expressed during differentiation and development. In the present study, over 10,000 primary spermatocytes and round spermatid cells were successfully isolated by LCM. Using the cDNAs from primary spermatocytes and round spermatids, SSH cDNAs library of primary spermatocyte-specific was constructed. The average insert size of the cDNA isolated from 75 randomly picked white clones was 500 bp, ranging from 250 bp to 1.7 kb. Using the dot-blot method, a total of 421 clones were examined, resulting in the identification of 390 positive clones emitting strong signals. Partial sequence of cDNAs prepared from each clone was determined with an overall success rate of 84.4%. Genes encoding cytochrome c oxidase II and the rescue factor-humanin were most frequently expressed in primary spermatocytes, suggesting their roles involved in meiosis.

Construction of a DNA library from chromosome 4 of rice(Oryza sativa)by microdissection

A simple method to create a chromosome-specific DNA library of rice, including microdissection, amplification,characterization and cloning, is described. Rice chromosome 4 from a metaphase cell has been isolated and amplified by the Linker Adapter PCR (LA-PCR). The PCR products were labeled as probes with DIG-11-dUTP using the random priming method.Southern blot analysis with rice genomic DNA and specific RFLP markers demonstrated that the PCR products were derived from rice chromosome 4. A large library comprising over 100,000recombinant plasmid microclones from rice chromosome 4was constructed. Colony hybridization showed that 58% of the clones contained single or low-copy sequences and 42%contained repetitive sequences. The size of inserts generated by PCR ranged from 140bp to 500bp.This method will facilitate cloning of the specific chromosome DNA markers and important genes of rice.

Gene profiles between non-invasive and invasive colon cancer using laser microdissection and polypeptide analysis

AIM: To explore the expression of differential gene expression profiles of target cell between non-invasive submucosal and invasive advanced tumor in colon carcinoma using laser microdissection (LMD) in combination with polypeptide analysis. METHODS: Normal colon tissue samples from 20 healthy individuals and 30 cancer tissue samples from early non-invasive colon cancer cells were obtained. The cells from these samples were used LMD independently after P27-based amplification. aRNA from advanced colon cancer cells and metastatic cancer cells of 40 cases were applied to LMD and polypeptide analysis, semiquantitative reverse transcribed polymerase chain reaction (RT-PCR) and immunohistochemical assays were used to verify the results of microarray and further identify differentially expressed genes in non-invasive early stages of colon cancer. RESULTS: Five gene expressions were changed in colon carcinoma cells compared with that of controls. Of the five genes, three genes were downregulated and two were upregulated in invasive submucosal colon carcinoma compared with non-invasive cases. The results were confirmed at the level of aRNA and gene expression. Five genes were further identified as differentially expressed genes in the majority ofcases (> 50%, 25/40) in progression of colon cancer, and their expression patterns of which were similar to tumor suppressor genes or oncogenes. CONCLUSION: This study suggested that combined use of polypeptide analysis might identify early expression profiles of five differential genes associated with the invasion of colon cancer. These results reveal that this gene may be a marker of submucosal invasion in early colon cancer.

Laser capture microdissection enables cellular and molecular studies of tooth root development

Epithelial-mesenchymal interactions（EMIs） are critical for tooth development.Molecular mechanisms mediating these interactions in root formation is not well understood.Laser capture microdissection（LCM） and subsequent microarray analyses enable large scale in situ molecular and cellular studies of root formation but to date have been hindered by technical challenges of gaining intact histological sections of non-decalcified mineralized teeth or jaws with well-preserved RNA.Here,we describe a new method to overcome this obstacle that permits LCM of dental epithelia,adjacent mesenchyme,odontoblasts and cementoblasts from mouse incisors and molars during root development.Using this method,we obtained RNA samples of high quality and successfully performed microarray analyses.Robust differences in gene expression,as well as genes not previously associated with root formation,were identified.Comparison of gene expression data from microarray with real-time reverse transcriptase polymerase chain reaction（RT-PCR） supported our findings.These genes include known markers of dental epithelia,mesenchyme,cementoblasts and odontoblasts,as well as novel genes such as those in the fibulin family.In conclusion,our new approach in tissue preparation enables LCM collection of intact cells with well-preserved RNA allowing subsequent gene expression analyses using microarray and RT-PCR to define key regulators of tooth root development.

Isolation of cardiac conduction system of rat heart by laser capture microdissection

Objective：To isolate ceils of cardiac conduction system （CCS） with laser capture microdissec tion （LCM） and extract and evaluate quality of small amount of RNA from ceils of CCS. Methods： Cryo star sections were followed by H-E staining. 20 pieces of H-E stained eryostat sections were scraped and its RNA was assessed to insure that RNA didn＇t degrade in dyeing and dehydration process. Ceils of CCS were captured with LCM and quality of small amount of RNA was verified with RT-PCR. Results： Ceils of CCS isolated with LCM had clear morphology after staining. High quality RNA was extracted from LCM samples and scraped tissues; 18S rRNA and 28S rRNA were seen distinctly on gel eleetrophoresis. Low level of small amount of RNA extracted from LCM sample was below the limit of detection on gel eleetrophoresis or ultraviolet speetrophotometer. The housekeeping genes β-aetin and GAPDH were successfully amplified with small amount of RNA. Conclusion ：This study resolves the problem of acquiring material of CCS precisely that hinders gene research of CCS. It is found out that the method is easy and reliable to extract and assess the quality of small amount of RNA from mierodisseeted ceils of CCS.

Development of a predictive model for increasing sperm retrieval sucpess by microdissection testicular sperm extraction in patients with nonobstructive azoospermia

Microdissection testicular sperm extraction(micro-TESE)is widely used to treat nonobstructive azoospermia.However,a good prediction model is required to anticipate a successful sperm retrieval rate before performing micro-TESE.This retrospective study analyzed the clinical records of 200 nonobstructive azoospermia patients between January 2021 and December 2021.The backward method was used to perform binary logistic regression analysis and identify factors that predicted a successful micro-TESE sperm retrieval.The prediction model was constructed using acquired regression coefficients,and its predictive performance was assessed using the receiver operating characteristic curve.In all,67 patients(sperm retrieval rate:33.5%)underwent successful micro-TESE.Follicle-stimulating hormone,anti-Miillerian hormone,and inhibin B levels varied significantly between patients who underwent successful and unsuccessful micro-TESE.Binary logistic regression analysis yielded the following six predictors:anti-Mullerian hormone(odds ratio[OR]=0.902,95%confidence interval[Cl]:0.821-0.990),inhibin B(OR=1.012,95%Cl:1.001-1.024),Klinefelter’s syndrome(OR=0.022,95%Cl:0.002-0.243),Y chromosome microdeletion(OR=0.050,95%Cl:0.005-0.504),cryptorchidism with orchiopexy(OR=0.085,95%Cl:0.008-0.929),and idiopathic nonobstructive azoospermia(OR=0.031,95%Cl:0.003-0.277).The prediction model had an area under the curve of 0.720(95%Cl:0.645-0.794),sensitivity of 65.7%,specificity of 72.2%,Youden index of 0.379,and cut-off value of 0.305 overall,indicating good predictive value and accuracy.This model can assist clinicians and nonobstructive azoospermia patients in decision-making and avoiding negative micro-TESE results.

Laser capture microdissection for biomedical research: towards high-throughput, multi-omics, and single-cell resolution

Spatial omics technologies have become powerful methods to provide valuable insights into cells and tissues within a complex context,significantly enhancing our understanding of the intricate and multifaceted biological system.With an increasing focus on spatial heterogeneity,there is a growing need for unbiased,spatially resolved omics technologies.Laser capture microdissection(LCM)is a cutting-edge method for acquiring spatial information that can quickly collect regions of interest(ROIs)from heterogeneous tissues,with resolutions ranging from single cells to cell populations.Thus,LCM has been widely used for studying the cellular and molecular mechanisms of diseases.This review focuses on the differences among four types of commonly used LCM technologies and their applications in omics and disease research.Key attributes of application cases are also highlighted,such as throughput and spatial resolution.In addition,we comprehensively discuss the existing challenges and the great potential of LCM in biomedical research,disease diagnosis,and targeted therapy from the perspective of high-throughput,multi-omics,and single-cell resolution.

Sperm retrieval rates and clinical outcomes for patients with different causes of azoospermia who undergo microdissection testicular sperm extraction-intracytoplasmic sperm injection

The aim of our study was to compare the sperm retrieval rates(SRRs)and clinical outcomes of patients with different causes of azoospermia who underwent microdissection testicular sperm extraction-intracytoplasmic sperm injection(micro-TESE-ICSI).We conducted a retrospective study at the Reproductive Medicine Center of Peking University Third Hospital in Beijing,China,from January 2014 to December 2017.This study examined 769 patients with nonobstructive azoospermia who underwent 347 cycles of micro-TESE-ICSI.Patients with azoospermia were classified into Group A(Klinefelter syndrome,n=284,125 cycles),Group B(azoospermia Y chromosome factor c[AZFc]microdeletion,n=91,64 cycles),Group C(cryptorchidism,n=52,39 cycles),Group D(previous mumps and bilateral orchitis,n=23,23 cycles),and Group E(idiopathic azoospermia,n=319,96 cycles).Clinical characteristics,SRR,embryonic development,and pregnancy outcomes of the patients were compared between all groups.Patients in Group D had the highest and most successful SRR.The average SRR for all patients was 46.0%.The rates of clinical pregnancy,implantation,and live birth in Group D were 78.3%,65.0%,and 74.0%,respectively,which were higher than those in all other groups(P<0.05).Group B patients had the lowest clinical pregnancy,implantation,and live birth rates of all groups(P<0.05).No differences were found in the miscarriage rate or birth defects among the groups(P>0.05).Patients with orchitis had the highest SRR and best clinical outcomes.Although AZFc microdeletion patients had a higher SRR,their clinical outcomes were worse.

Predictive value of FSH, testicular volume, and histopathological findings for the sperm retrieval rate of microdissection TESE in nonobstructive azoospermia： a meta-analysis

We performed this meta-analysis to evaluate the predictive value of different parameters in the sperm retrieval rate （SRR） of microdissection testicular sperm extraction （TESE） in patients with nonobstructive azoospermia （NOA）. All relevant studies were searched in PubMed, Web of Science, EMBASE, Cochrane Library, and EBSCO. We chose three parameters to perform the meta-analysis： follicle-stimulating hormone （FSH）, testicular volume, and testicular histopathological findings which included three patterns： hypospermatogenesis （HS）, maturation arrest （MA）, and Sertoli-cell-only syndrome （SCOS）. If there was a threshold effect, only the area under the summary receiver operating characteristic curve （AUSROC） was calculated. Otherwise, the pooled sensitivity, specificity, positive likelihood ratio （PLR）, negative likelihood ratio （NLR）, and the diagnostic odds ratio （DOR） were also calculated. Twenty-one articles were included in our study finally. There was a threshold effect among studies investigating FSH and SCOS. The AUSROCs of FSH, testicular volume, HS, MA, and SCOS were 0.6119, 0.6389, 0.6758, 0.5535, and 0.2763, respectively. The DORs of testicular volume, HS, and MA were 1.98, 16.49, and 1.26, respectively. The sensitivities of them were 0.80, 0.30, and 0.27, while the specificities of them were 0.35, 0.98, and 0.76, respectively. The PLRs of them were 1.49, 10.63, and 1.15, respectively. And NLRs were 0.73, 0.72, and 0.95, respectively. All the investigated factors in our study had limited predictive value. However, the histopathological findings were helpful to some extent. Most patients with HS could get sperm by microdissection TESE.

Clinical outcomes of microdissection testicular sperm extraction-intracytoplasmic sperm injection with fresh or cryopreserved sperm in patients with nonobstructive azoospermia

We performed this study to evaluate the clinical outcomes of microdissection testicular sperm extraction-intracytoplasmic sperm injection(micro-TESE-ICSI)treatment that used fresh or cryopreserved sperm in patients with nonobstructive azoospermia(NOA).A total of 338 NOA patients with 344 consecutive cycles received treatment in the reproductive medicine center of Peking University Third Hospital in Beijing,China,from January 2014 to December 2017.Fresh oocytes and fresh sperm were used in 222 patients with 234 cycles(Group A).Fresh oocytes and cryopreserved sperm were used in 116 patients with 110 cycles(Group B).We compared patient characteristics,embryonic development,and pregnancy outcomes between Groups A and B.There was no statistical difference in the patient characteristics,and no differences were observed with fertilization or quality embryo rates between Groups A and B.The rates of clinical pregnancy and live birth were both higher for Group A than those for Group B(both P<0.05).In conclusion,fresh testicular sperm appears to produce better ICSI outcomes than cryopreserved testicular sperm in patients with NOA.

Predictive factors for successful sperm retrieval by microdissection testicular sperm extraction in men with nonobstructive azoospermia and a history of cryptorchidism

This study aims to explore the factors influencing the success rate of the microdissection testicular sperm extraction(Micro-TESE)in patients with nonobstructive azoospermia(NOA)and cryptorchidism.Clinical data of 162 patients with cryptorchidism who underwent Micro-TESE due to infertility from December 2015 to May 2020 in the First Affiliated Hospital of Nanjing Medical University were analyzed retrospectively.In the univariate analysis,significant differences in the age of patient at the time of orchidopexy(median[interquartile range,IQR]:7.0[4.0–11.0]years vs 11.5[9.0–14.5]years,P<0.001),interval between orchidopexy and Micro-TESE(mean±standard deviation:17.5±5.0 years vs 14.4±4.4 years,P<0.001),severity of cryptorchidism(unilateral[62.8%]vs bilateral[31.6%],P<0.001;location of cryptorchidism,intra-abdominal[27.3%]vs inguinal[44.8%]vs suprascrotal[66.7%],P<0.001),volume of the dominant testis(median[IQR]:17.00[15.00–19.00]ml vs 14.50[11.75–16.25]ml,P<0.001),and levels of follicle-stimulating hormone(FSH;P=0.004)and testosterone(P=0.006)were observed between the successful and failed sperm extraction groups.After conducting the multivariate analysis,four of these factors,including unilateral/bilateral cryptorchidism(P<0.001),location of cryptorchidism(P=0.032),age of orchidopexy(P<0.001),and dominant testicular volume,were adopted in the clinical prediction model to evaluate preoperatively the success rate of Micro-TESE for patients with NOA and cryptorchidism.The likelihood of successful sperm retrieval by Micro-TESE in men with NOA and cryptorchidism increased in patients with mild forms of cryptorchidism.

Sperm fine-needle aspiration (FNA)mapping after failed microdissection testicular sperm extraction (TESE):location and patterns of found sperm

We sought to evaluate the ability of fine-needle aspiration (FNA)mapping to find sperm and to guide sperm retrieval after failed microdissection testicular sperm extraction (micro-TESE)in nonobstructive azoospermic men.In this study of consecutive male infertility cases,interventions included testicular FNA mapping and subsequent sperm retrieval.Outcomes included the frequency and location of found sperm on FNA maps after failed micro-TESE and the salvage sperm retrieval success.Among 548 patients undergoing FNA mapping from 2010 to 2016,82 men with previous micro-TESE procedures were identified.The mean time between micro-TESE and FNA mapping was 2.2 years.A total of 2825 (1424 on right and 1401 on left)sites were mapped.At least one site revealed mature sperm in 24 (29.3%)of 82 men with prior failed micro-TESE procedures.There was an equal likelihood of detecting sperm in either testis (6.1%right;5.7%left;P=0.58).Digital "heat maps"revealed differences in sperm findings within the testis with mature sperm more likely found in the testis periphery rather than centrally.Fifteen (62.5%)patients subsequently underwent sperm retrieval procedures guided by FNA maps.Sufficient sperm were retrieved in all cases,and in 10 (66.7%)of 15 cases,extra sperm were frozen for future use.in a significant proportion of failed micro-TESE procedures representing the largest study to date,sperm were detected by FNA mapping and could be reliably retrieved through FNA map-guided surgical sperm retrieval.When present,sperm were more likely to be found in the testis periphery rather than centrally with FNA mapping.

Microdissection of chromosome 7B of common wheat and cloning of low-copy specific DNA sequences

The 7B chromosome of common wheat was microdissected from pollen mother cells of the 7B monosomic line of common wheat cv. Chinese Spring (CS). After proteinase K and DNA topoisomerase Ⅰtreatments, the isolated chromosomes were subjected to 1—3 rounds of DOPPCR amplification, which produced continuous DNA fragments ranging from 150 to 700 bp. Genomic Southern hybridization confirmed that the PCR products were originated from the wheat genome. Cloning of portion ( 】 200 bp) of the 3rd round DOP-PCR products (50 μL) could generate about 20 000 recombinant clones. Characterization of 50 randomly chosen clones indicated that 21 clones produced discrete PCR products with the size of 240—600 bp. Dot-blot hybridization showed that among the 21 clones, 11 (～ 55%) were of low-copy nature while 10 (～45%) were repetitive. Southern hybridization with the complete set of the CS 'nullisomic-tetrasomic (NT)' lines demonstrated that all the 6 low-copy clones were specific to either chromosome 7B or the 7th