[Pan-cancer analysis of ubiquitin-specific protease 7 and its expression changes in the carcinogenesis of scar ulcer]

Objective: To explore the biological role and clinical significance of ubiquitin-specific protease 7 (USP7) in the carcinogenesis of scar ulcer. Methods: A retrospective observational study combined with bioinformatics analysis was used. The RNA expression profile data of USP7 in tumor and/or its corresponding paracancular normal tissue were obtained from The Cancer Genome Atlas (TCGA) database and the Gene Expression Omnibus database, and the RNA sequencing data were transformed by log2. The variations of USP7 gene were analyzed by cBioPortal database. The USP7 mRNA expression in tumor and adjacent normal tissue in TCGA database were obtained by using the "Gene_DE" module in TIMER 2.0 database. The survival rates of patients with high and low USP7 expression in cutaneous melanoma (SKCM), cervical squamous cell carcinoma (CESC), lung squamous cell carcinoma (LUSC), and head and neck squamous cell carcinoma (HNSC) were analyzed using the Gene Expression Profile Interactive Analysis 2 (GEPIA2) database, and the Kaplan-Meier survival curves were drawn. Sangerbox database was used to analyze the correlation of USP7 expression in pan-cancer with microsatellite instability (MSI) or tumor mutation burden (TMB) pan-cancer. Through the "correlation analysis" module in the GEPIA2 database, the correlation of USP7 expression in pan-cancer with the expression levels of five DNA mismatch repair genes (MLH1, MSH2, MSH6, PMS2, and EPCAM) and three essential DNA methyltransferases (DNMT)--DNMT1, DNMT3A, and DNMT3B were evaluated. The USP7 expression in CESC, HNSC, LUSC, and SKCM and its correlation with infiltration of immune cells (B cells, CD4+ T cells, CD8+ T cells, neutrophils, macrophages, and dendritic cells) were analyzed by the "Immune-Gene" module in TIMER 2.0 database. The "Similar Genes Detection" module of GEPIA2 database was used to obtain the top 100 protein sets with similar expression patterns to USP7. Intersection analysis was performed between the aforementioned protein sets and the top 50 protein sets that were directly physically bound to USP7 obtained by using the STRING database. Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analysis were performed for the two protein sets mentioned above using the DAVID database. The samples of normal skin, hypertrophic scar, scar ulcer, and scar carcinoma with corresponding clinicopathologic features were collected from the Department of Pathology of Tongren Hospital of Wuhan University & Wuhan Third Hospital from October 2018 to October 2022, and the USP7 expression in tissue was detected by immunohistochemical method, with the number of samples of 6. Data were statistically analyzed with Log-rank test, one-way analysis of variance, and Bonferroni test. Results: In pan-cancer, the main gene variations of USP7 were mutation and amplification, and the top 3 tumors with the highest variation frequency (>6%) were bladder urothelial carcinoma, SKCM, and endometrial carcinoma. The main mutation of USP7 gene in pan-cancer was missense mutation. In SKCM with the highest mutation frequency, the main type of mutation was missense mutation in USP7_ICP0_bdg domain. USP7 mRNA expression in breast invasive carcinoma, bile duct carcinoma, colon carcinoma, esophageal carcinoma, HNSC, renal chromophobe cell carcinoma, hepatocellular carcinoma, lung adenocarcinoma, LUSC, prostate carcinoma, and gastric carcinoma was significantly higher than that in corresponding paracancer normal tissue (P<0.05). USP7 mRNA expression in glioblastoma multiforme, renal clear cell carcinoma, renal papillary cell carcinoma, and thyroid carcinoma was significantly lower than that in corresponding paracancular normal tissue (P<0.05). In addition, USP7 mRNA expression in SKCM metastases was much higher than that in primary tumor tissue (P<0.05). Survival curves showed no significant difference in survival rate between patients with high USP7 expression and patients with low USP7 expression in CESC, HNSC, LUSC, and SKCM (Log-rank P>0.05, with hazard ratios of 1.00, 0.99, 1.00, and 1.30, respectively). USP7 expression in colon cancer, colorectal cancer, thymic cancer, and thyroid cancer was negatively correlated with TMB (with Pearson correlation coefficients of -0.26, -0.19, -0.19, and 0.11, respectively, P<0.05). USP7 expression in glioma, CESC, lung adenocarcinoma, mixed renal carcinoma, and LUSC was positively correlated with MSI expression (with Pearson correlation coefficients of 0.22, 0.14, 0.15, 0.08, and 0.14, respectively, P<0.05), and USP7 expression in colon cancer, colorectal cancer, invasive breast cancer, prostate cancer, HNSC, thyroid cancer, and diffuse large B-cell lymphoma were significantly negatively correlated with MSI expression (with Pearson correlation coefficients of -0.31, -0.27, -0.13, -0.19, -0.16, -0.18, and -0.53, respectively, P<0.05). The expression of USP7 in CESC was positively correlated with that of both MSH2 and MSH6 (with Spearman correlation coefficients of 0.51 and 0.44, respectively, P<0.05), and the expression of USP7 in HNSC was positively correlated with the expression of EPCAM, MLH1, MSH2, MSH6, and PMS2 (with Spearman correlation coefficients of 0.39, 0.14, 0.49, 0.54, and 0.41, respectively, P<0.05), and the expression of USP7 in LUSC was positively correlated with the expression of EPCAM, MSH2, MSH6, and PMS2 (with Spearman correlation coefficients of 0.20, 0.36, 0.40, and 0.34, respectively, P<0.05), and the expression of USP7 in SKCM was positively correlated with the expression of EPCAM, MLH1, MSH2, MSH6, and PMS2 (with Spearman correlation coefficients of 0.11, 0.33, 0.42, 0.55, and 0.34, respectively, P<0.05). The expression of USP7 in CESC, HNSC, LUSC, and SKCM was significantly positively correlated with the expression of DNMT1, DNMT3A, and DNMT3B (with Spearman correlation coefficients of 0.42, 0.34, 0.22, 0.45, 0.52, 0.22, 0.36, 0.36, 0.22, 0.38, 0.46, and 0.21, respectively, P<0.05). The expression of USP7 in CESC, HNSC, LUSC, and SKCM was positively correlated with CD4+ T cell infiltration (with Partial correlation coefficients of 0.14, 0.22, 0.13, and 0.16, respectively, P<0.05). Being similar to the pattern of USP7 expression and ranked among top 100 protein sets, the top 5 proteins were C16orf72, BCLAF1, UBN, GSPT1, ERI2 (with Spearman correlation coefficients of 0.83, 0.74, 0.73, and 0.72, respectively, all P values<0.05). The top 50 protein sets that directly physically bind to USP7 overlapped with the aforementioned protein set by only one protein, thyroid hormone receptor interaction factor 12. KEGG enrichment analysis showed that USP7 related genes were involved in cell cycle, spliceosome, cell senescence, and p53 signal pathway. GO enrichment analysis showed that USP7 related genes were involved in transcriptional regulation, protein ubiquitination, DNA repair, and cytoplasmic pattern recognition receptor signal pathways. Analysis of clinical samples showed that USP7 expression was significantly higher in hypertrophic scars (0.35±0.05), scar ulcers (0.43±0.04), and scar cancers (0.61±0.03) than in normal skin (0.18±0.04), P<0.05. Conclusions: USP7 may be a clinical biomarker for the progression of cicatricial ulcer cancer.

Simplified Genomic Data Revealing the Decline of Aleuritopteris grevilleoides Population Accompanied by the Uplift of Dry-Hot Valley in Yunnan, China

Understanding the evolutionary history of endangered species is crucial for identifying the main reasons for species endangerment in the past and predicting the changing trends and evolutionary directions of their future distribution. In order to study the impact of environmental changes caused by deep valley incision after the uplift of the Qinghai-Tibet Plateau on endangered species, we collected 23 samples belonging to four populations of Aleuritopteris grevilleoides, an endangered fern endemic to the dry-hot valleys (DHV) of Yunnan. Single-nucleotide variation sites (SNPs) were obtained by the genotyping-by-sequencing (GBS) method, and approximately 8085 SNP loci were identified. Through the reconstruction and analysis of genetic diversity, population structure, population dynamics, evolution time, and ancestral geographical distribution, combined with geological historical events such as the formation of dry-hot valleys, this study explores the formation history, current situation, reasons for endangerment and scientifically sound measures for the protection of A. grevilleoides. In our study, A. grevilleoides had low genetic diversity (Obs_Het = 0.16, Exp_Het = 0.32, Pi = 0.33) and a high inbreeding coefficient (Fis = 0.45). The differentiation events were 0.18 Mya, 0.16 Mya, and 0.11 Mya in the A. grevilleoides and may have been related to the formation of terraces within the dry-hot valleys. The history of population dynamics results shows that the diversion of the river resulted in a small amount of gene flow between the two clades, accompanied by a rapid increase in the population at 0.8 Mya. After that, the effective population sizes of A. grevilleoides began to contract continuously due to topographic changes resulting from the continuous expansion of dry-hot valleys. In conclusion, we found that the environmental changes caused by geological events might be the main reason for the changing population size of A. grevilleoides.

Genome size evolution of the extant lycophytes and ferns

Ferns and lycophytes have remarkably large genomes. However, little is known about how their genome size evolved in fern lineages. To explore the origins and evolution of chromosome numbers and genome size in ferns, we used flow cytometry to measure the genomes of 240 species (255 samples) of extant ferns and lycophytes comprising 27 families and 72 genera, of which 228 species (242 samples) represent new reports. We analyzed correlations among genome size, spore size, chromosomal features, phylogeny, and habitat type preference within a phylogenetic framework. We also applied ANOVA and multinomial logistic regression analysis to preference of habitat type and genome size. Using the phylogeny, we conducted ancestral character reconstruction for habitat types and tested whether genome size changes simultaneously with shifts in habitat preference. We found that 2C values had weak phylogenetic signal, whereas the base number of chromosomes (x) had a strong phylogenetic signal. Furthermore, our analyses revealed a positive correlation between genome size and chromosome traits, indicating that the base number of chromosomes (x), chromosome size, and polyploidization may be primary contributors to genome expansion in ferns and lycophytes. Genome sizes in different habitat types varied significantly and were significantly correlated with habitat types; specifically, multinomial logistic regression indicated that species with larger 2C values were more likely to be epiphytes. Terrestrial habitat is inferred to be ancestral for both extant ferns and lycophytes, whereas transitions to other habitat types occurred as the major clades emerged. Shifts in habitat types appear be followed by periods of genomic stability. Based on these results, we inferred that habitat type changes and multiple whole-genome duplications have contributed to the formation of large genomes of ferns and their allies during their evolutionary history.

Nicotinic Acetylcholine Receptor Alpha7 Subunit Mediates Vagus Nerve Stimulation-Induced Neuroprotection in Acute Permanent Cerebral Ischemia by a7nAchR/JAK2 Pathway

Background

The role of nicotinic acetylcholine receptor alpha7 subunit (a7nAchR) in the treatment of acute cerebral ischemia by VNS has not been thoroughly clarified to date. Therefore, this study aimed to investigate the specific role of a7nAchR and explore whether this process is involved in the mechanisms of VNS-induced neuroprotection in rats undergoing permanent middle cerebral artery occlusion (PMCAO) surgery.

Material/Methods

Rats received a7nAChR antagonist (A) or antagonist placebo injection for control (AC), followed by PMCAO and VNS treatment, whereas the a7nAChR agonist (P) was utilized singly without VNS treatment but only with PMCAO pretreatment. The rats were randomly divided into 6 groups: sham PMCAO, PMCAO, PMCAO+VNS, PMCAO+VNS+A, PMCAO+VNS+AC, and PMCAO+P. Neurological function and cerebral infarct volume were measured to evaluate the level of brain injury at 24 h after PMCAO or PMCAO-sham. Moreover, the related proteins levels of a7nAChR, p-JAK2, and p-STAT3 in the ischemic penumbra were assessed by Western blot analysis.

Results

Rats pretreated with VNS had significantly improved neurological function and reduced cerebral infarct volume after PMCAO injury (p<0.05). In addition, VNS enhanced the levels of a7nAchR, p-JAK2, and p-STAT3 in the ischemic penumbra (p<0.05). However, inhibition of a7nAchR not only attenuated the beneficial neuroprotective effects induced by VNS, but also decreased levels of p-JAK2 and p-STAT3. Strikingly, pharmacological activation of a7nAchR can partially substitute for VNS-induced beneficial neurological protection.

Conclusions

These results suggest that a7nAchR is a pivotal mediator of VNS-induced neuroprotective effects on PMCAO injury, which may be related to suppressed inflammation via activation of the a7nAchR/JAK2 anti-inflammatory pathway.

Effect of cilostazol on the progression of carotid intima-media thickness: a meta-analysis of randomized controlled trials

BACKGROUND

It has been well established that cilostazol has anti-proliferative effect against in-stent restenosis. However, it remains unclear whether cilostazol can prevent the progression of carotid atherosclerosis.

METHODS AND RESULTS

We performed a meta-analysis of all relevant randomized controlled trials (RCTs) to evaluate the effect of cilostazol on the progression of carotid intima-media thickness (IMT). Five RCTs with 698 patients [597 subjects with type 2 diabetes mellitus (T2DM)] were included in this study. Cilostazol was associated with a significant reduction in the progression of carotid IMT (WMD, -0.08mm, 95% CI -0.13, -0.04; P=0.00003). Subgroup analysis shows that cilostazol monotherapy or addition to dual antiplatelet therapy (aspirin and clopidogrel) was superior to placebo (WMD, -0.04mm, 95% CI -0.05, -0.03; P<0.00001), no antiplatelet medication (WMD, -0.12mm, 95% CI -0.21, -0.03; P=0.008), aspirin monotherapy (WMD, -0.06mm, 95% CI -0.12, 0.00; P=0.04) or dual antiplatelet therapy (WMD, -0.16mm, 95% CI -0.30, -0.02; P=0.03) in preventing the progression of carotid IMT. Cilostazol resulted in a significant decrease in total cholesterol (WMD -8.47mg/dl, 95% CI -14.18, -2.75; P=0.004) and LDL-C (WMD -8.25mg/dl, 95% CI -14.15, -2.36; P=0.006) and favorable trends in reducing triglyceride (WMD -15.83mg/dl, 95% CI -32.14, 0.48; P=0.06).

CONCLUSION

It suggests that cilostazol may have beneficial effects in preventing the progression of carotid atherosclerosis and improving pro-atherogenic lipid profile, especially in patients with T2DM. Whether the anti-atherosclerotic effect of cilostazol is independent of improving pro-atherogenic dyslipidemia is worth further investigation.

Clinical Study of Amiodarone-Associated Torsade De Pointes in Chinese People

OBJECTS

Amiodarone-associated torsade de pointes (Tdp) has been reported increasingly in China in recent years. In this study, we made clinical analysis of amiodarone-associated Tdp in Chinese people.

METHODS

Two major Chinese medical databases were searched to identify articles published during the last 26 years that presented data on amiodarone-associated proarrhythmic events. The articles were divided into two categories: case reports and observational studies.

RESULTS

Fifty-two Chinese-language case reports with 98 patients and 2 patients registered in our hospital, total 100 patients about amiodarone-associated Tdp, were enrolled in the study. Amiodarone-associated Tdp occurred more frequently in females (68.0%, 68/100). The major primary disease of females was rheumatic heart disease (40.7%, 24/59), while that of males was coronary heart disease (45.8%, 11/24). In most patients, Tdp occurred repeatedly and terminated in 24-48 hours. Some Tdp worsen to ventricular fibrillation and caused 19 patients' death (mortality rate 21.8%, 19/87). Known predisposing factors to the development of Tdp, such as heart failure, hypokalemia, drugs combination, and bradyarrhythmia, existed in many cases. Tdp also occurred in six patients (4 females, 2 males) without any known predisposing factors except QTc interval prolongation. Fourteen observational studies each reported data from at least 100 patients who were treated with amiodarone for at least 1 month. Of 2,354 patients included in these studies, 455 patients exposed to amiodarone were reported to have proarrhythmic events (an overall incidence of 19.3%), while only 4 patients were reported to have Tdp or ventricular fibrillation (an incidence of 0.17%).

CONCLUSIONS

In conclusion, approximately one-fifth of the patients have amiodarone-induced proarrhythmic events, while the incidence of Tdp or ventricular fibrillation is remarkably low. Amiodarone-associated Tdp occurred more frequently in Chinese females. Known predisposing factors for occurrence of Tdp prevailed in Chinese patients. QTc interval prolongation may be an independent risk factor of amiodarone-associated Tdp.

Characterization and mapping of Rpi1, a gene that confers dominant resistance to stalk rot in maize

The maize inbred lines 1145 (resistant) and Y331 (susceptible), and the F(1), F(2) and BC(1)F(1) populations derived from them were inoculated with the pathogen Pythium inflatum Matthews, which causes stalk rot in Zea mays. Field data revealed that the ratio of resistant to susceptible plants was 3:1 in the F(2) population, and 1:1 in the BC(1)F(1)population, indicating that the resistance to P. inflatum Matthews was controlled by a single dominant gene in the 1145xY331 cross. The gene that confers resistance to P. inflatum Matthews was designated Rpi1 for resistance to P. inflatum) according to the standard nomenclature for plant disease resistance genes. Fifty SSR markers from 10 chromosomes were first screened in the F(2) population to find markers linked to the Rpi1 gene. The results indicated that umc1702 and mmc0371 were both linked to Rpi1, placing the resistance gene on chromosome 4. RAPD (randomly amplified polymorphic DNA) markers were then tested in the F(2)population using bulked segregant analysis (BSA). Four RAPD products were found to show linkage to the Rpi1 gene. Then 27 SSR markers and 8 RFLP markers in the region encompassing Rpi1 were used for fine-scale mapping of the resistance gene. Two SSR markers and four RFLP markers were linked to the Rpi1 gene. Finally, the Rpi1 gene was mapped between the SSR markers bnlg1937 and agrr286 on chromosome 4, 1.6 cM away from the former and 4.1 cM distant from the latter. This is the first time that a dominant gene for resistance to maize stalk rot caused by P. inflatum Matthews has been mapped with molecular marker techniques.

Molecular tagging and genetic mapping of the disease resistance gene RppQ to southern corn rust

Southern corn rust (SCR), Puccinia polysora Underw, is a destructive disease in maize ( Zea mays L.). Inbred line Qi319 is highly resistant to SCR. Results from the inoculation test and genetic analysis of SCR in five F(2) populations and five BC(1)F(1 )populations derived from resistant parent Qi319 clearly indicate that the resistance to SCR in Qi319 is controlled by a single dominant resistant gene, which was named RppQ. Simple sequence repeat (SSR) analysis was carried out in an F(2) population derived from the cross "Qi319x340". Twenty SSR primer pairs evenly distributed on chromosome10 were screened at first. Out of them, two primer pairs, phi118 and phi 041, showed linkage with SCR resistance. Based on this result, eight new SSR primer pairs surrounding the region of primers phi118 and phi 041 were selected and further tested regarding their linkage relation with RppQ. Results indicated that SSR markers umc1,318 and umc 2,018 were linked to RppQ with a genetic distance of 4.76 and 14.59 cM, respectively. On the other side of RppQ, beyond SSR markers phi 041 and phi118, another SSR marker umc1,293 was linked to RppQ with a genetic distance of 3.78 cM. Because the five linkage SSR markers (phi118, phi 041, umc1,318, umc 2,018 and umc1,293) are all located on chromosome 10, the RppQ gene should also be located on chromosome 10. In order to fine map the RppQ gene, AFLP (amplified fragment length polymorphism) analysis was carried out. A total 54 AFLP primer combinations were analyzed; one AFLP marker, AF1, from the amplification products of primer combination E-AGC/M-CAA, showed linkage with the RppQ gene in a genetic distance of 3.34 cM. Finally the RppQ gene was mapped on the short arm of chromosome 10 between SSR markers phi 041 and AFLP marker AF1 with a genetic distance of 2.45 and 3.34 cM respectively.

Genetic analysis and molecular mapping of maize (Zea mays L.) stalk rot resistant gene Rfg1

One single pathogen Fusarium graminearum Schw. was inoculated to maize inbred lines 1,145 (Resistant) and Y331 (Susceptive), and their progenies of F(1), F(2) and BC(1)F(1) populations. Field statistical data revealed that all of the F(1) individuals were resistant to the disease and that the ratio of resistant plants to susceptive plants was 3:1 in the F(2) population, and 1:1 in the BC(1)F(1 )population. The results revealed that a single dominant gene controls the resistance to F. graminearum Schw. The resistant gene to F. graminearum Schw. was denominated as Rfg1 according to the standard principle of the nomenclature of the plant disease resistant genes. RAPD (randomly amplified polymorphic DNA) combined with BSA (bulked segregant analysis) analysis was carried out in the developed F(2) and BC(1)F(1 )populations, respectively. Three RAPD products screened from the RAPD analysis with 820 Operon 10-mer primers showed the linkage relation with the resistant gene Rfg1. The three RAPD amplification products (OPD-20(1000), OPA-04(1100) and OPY-04(900)) were cloned and their copy numbers were determined. The results indicated that only OPY-04(900) was a single-copy sequence. Then, OPY-04(900) was used as a probe to map the Rfg1 gene with a RIL F(7) mapping population provided by Henry Nguyen, which was developed from the cross "S3xMo17". Rfg1 was primarily mapped on chromosome 6 between the two linked markers OPY-04(900) and umc21 (Bin 6.04-6.05). In order to confirm the primary mapping result, 25 SSR (simple sequence repeat) markers and six RFLP (restriction fragment length polymorphism) markers in the Rfg1 gene-encompassing region were selected, and their linkage relation with Rfg1 was analyzed in our F(2) population. Results indicated that SSR marker mmc0241 and RFLP marker bnl3.03 are flanking the Rfg1 gene with a genetic distance of 3.0 cM and 2.0 cM, respectively. This is the first time to name and to map a single resistant gene of maize stalk rot through a single pathogen inoculation and molecular marker analysis.

Genetic analysis, molecular tagging and mapping of the thermo-sensitive genic male-sterile gene (wtms1) in wheat

A thermo-sensitive genic male-sterile (TGMS) wheat line ( Triticum aestivum L.) BNY-S was obtained from the spontaneous mutant of BNY-F. Its fertility was decided by the temperature during the differentiation stage of the spikelets. BNY-S was completely sterile when the temperature was lower than 10 degrees C during the differentiation stage of the spikelets, but fertile when the temperature was higher than 10 degrees C. Genetic analysis indicated that the sterility of BNY-S was controlled by a single recessive gene, which was named as wtms1. An F(2) population, consisting of 3,000 individuals from the cross between BNY-S and Lankao 52-24, was used for genetic analysis and statistical analysis of the TGMS and, out of them, 158 sterile and 93 fertile extremes were present for molecular tagging and mapping of the wtms1 gene. SSR (simple sequence repeat) and AFLP (amplified fragment length polymorphism) techniques combined with BSA (bulked segregant analysis) were used to screen markers linked to the target gene. As a result, wtms1 was preliminarily mapped on chromosome 2B according to SSR analysis. In AFLP analysis, 14 polymorphic AFLP loci were identified with a linkage relation to the wtms1 gene. Then linkage analysis using the F(2) population showed that three of them, E: AAG/M: CTA(163), E: AGG/M: CTC(220) and E: ACA/M: CTA(160), were linked to the wtms1 gene relatively close to a genetic distance of 6.9 cM, 6.9 cM and 13.9 cM, respectively. Finally, the wtms1 gene was mapped between the SSR marker Xgwm 374 and the AFLP marker E: AAG/M: CTA(163) with the distance of 4.8 cM and 6.9 cM, respectively. A partial linkage map was constructed according the SSR and AFLP data.

Tagging and mapping of rice sheath blight resistant gene

Sheath blight (Rhizoctonia solani Kühn) is one of the severe rice diseases worldwide. In this study, an F(2) population from a cross between "4011" and "Xiangzaoxian19" is used to identify molecular markers linked with the resistant trait. "4011" was a transgenic rice cultivar carrying a resistant gene to sheath blight, while "Xiangzaoxian19" is a highly susceptible one. As a result, five molecular markers, including three RFLP markers converted from RAPD and AFLP markers, and two SSR markers were identified to link with the sheath blight resistant gene. This dominant resistant gene was named as R sb 1 and mapped on rice chromosome 5. The linkage distance between the markers (E-AT:M-CAC(120), E-AT:M-CTA(230), OPN-16(2000), RM164(320) and RM39(300)) and R sb 1 was 1.6 cM, 9.9 cM, 1.6 cM, 15.2 cM and 1.6 cM, respectively.

[Application of isonucleus and isocytoplasmic lines in the study of maize CMS]

Between wild fertile type (F) and its sterile mutant (cms), if their nucleus and cytoplasm are the same, this wild fertile type (F) and its sterile mutant (cms) are called isonucleus and isocytoplasmic lines. The maize mtDNAs of isonucleus and isocytoplasmic lines (I), wild fertile type 478(F) and its sterile mutant 478-cms, were analyzed by RAPD. 94 primers were screened, 3 polymorphic products, OPZ-19(420), OPAA-15(600) and OPS-01(400), were amplified between 478(F) and 478-cms. The results showed that mtDNAs in isonucleus and isocytoplasmic lines were more homologous than that in others. There is minor mtDNA difference between the fertile type (F) and its sterile type (cms) in a pair of isonucleus and isocytoplasmic lines. The polymorphism detected in isonucleus and isocytoplasmic lines may be more closely linked with the gene of fertility. Therefore, isonucleus and isocytoplasmic line is an excellent system in the study of CMS. Sister isonucleus and isocytoplasmic lines are consisted of 2 groups of isonucleus and isocytoplasmic lines in which their nucleus are not all the same but closely related, their cytoplasm are the same. Using sister isonucleus and isocytoplasmic lines is equal to determining the change of fertility by transferring one cytoplasm into the isonucleus. Isonucleus and isocytoplasmic lines (II) are consisted of Su478(F) and Su478-cms. Isonucleus and isocytoplasmic lines (I) and (II) are sister isonucleus and isocytoplasmic lines. The polymorphic products, OPZ-19(420) and OPAA-15(600), can also be obtained in isonucleus and isocytoplasmic lines (II). The 2 polymorphic products OPZ-19(420) and OPAA-15(600) are existed in both of the isonucleus and isocytoplasmic lines. This showed that isonucleus and isocytoplasmic lines are practicable in the study of CMS, and that common polymorphism in isonucleus and isocytoplasmic lines may be related more directly to fertility.