Radical effects on mutation spectra in lambda phage.

Mutations in the lambda repressor gene cI (710 bp) were induced by 60Co-gamma radiation in dissolved lambda phage DNA. After in vitro DNA packaging to lambda phage particles (pack phage) and phenotypic expression of the mutants, DNA was sequenced directly. Two-thirds of mutations were located in the amino terminus region of the gene without any signs of hotspots. Changes consisted of (+1) insertions (25%) and base substitutions (75%). Transitions were exclusively G/C to A/T. Transversions were mostly G/C to C/G and few G/C to T/A. We did not find A/T to T/A transversions, A/T to G/C transitions, deletions and gross rearrangements. In most of the base substitutions a pre-existing base pair had been replaced by an A/T pair; this might come from 'non-instructional sites' like abasic sites. Several mechanisms for base substitutions are considered.     

氨基糖苷类抗生素致聋家系线粒体DNA 12S和16S rRNA基因突变分析

目的:研究线粒体rRNA基因突变与氨基糖苷类抗生素致聋遗传易感性的关系,为建立相应的基因诊断方法提供依据。方法:收集5个有明确氨基糖苷类抗生素应用史的耳聋家系27名成员的外周静脉血标本,从白细胞中提取DNA,PCR扩增线粒体DNA片段,Alw26I限制性内切酶分析和DNA序列分析检测A1555G点突变,并对其中一个家系进行了线粒体DNA12S和16S rRNA基因全序列分析。结果:家系A、C、D和E的21份样品均为A1555G点突变阳性,家系B的6份样品为A1555G点突变阴性。家系B线粒体DNA12S和16S rRNA基因全序列分析显示,该家系存在16S rRNA基因第2227位“AA”插入突变。结论:本研究发现了一个A1555G点突变阴性的氨基糖苷类抗生素致聋家系,说明线粒体DNA A1555G点突变不是氨基糖苷类抗生素遗传易感性惟一的分子基础,对氨基糖苷类抗生素致聋遗传易感性的预测仅检测A1555G点突变是不够的,应与mtDNA其他相关突变位点的检测结合起来。     

Genetic susceptibility to thymic lymphomas and K-ras gene mutation in mice after exposure to X-rays and N-ethyl-N-nitrosourea

PURPOSE: Ras activation is one of the major mechanisms for the development of murine thymic lymphomas by radiation and chemical carcinogens. To gain insight into the relationship between genetic susceptibility and ras gene mutation, the frequency and spectrum of ras gene mutation was examined in thymic lymphomas from susceptible and resistant mice. MATERIALS AND METHODS: K- and N-ras mutations in thymic lymphomas that arose in X-ray-irradiated and N-ethyl-N-nitrosourea (ENU)-treated mice of susceptible C57BL/6, rather resistant C3H and their hybrid B6C3F1 were analysed by polymerase chain reaction-single-strand conformation polymorphism and subsequent DNA sequencing. RESULTS: C57BL/6 exhibited a higher incidence of thymic lymphomas after exposure to X-rays and ENU than C3H, with B6C3F1 being intermediate. K-ras gene mutations occurred frequently in the pathogenesis of ENU-induced thymic lymphomas in susceptible C57BL/6 as opposed to resistant C3H. The ras mutations were more frequent in ENU-induced thymic lymphomas than X-ray-induced thymic lymphomas, and with the latter, there was no clear evidence for strain differences, suggesting that the genetic susceptibility to X-rays was independent of ras activation. The mutations of K-ras in thymic lymphomas from C57BL/6 were predominantly GGT to GAT in codon 12, whereas this mutation type was never found in those from C3H. No strain difference was observed in the nucleotide sequence or expression levels of O(6)-alkylguanine alkyltransferase, indicating that this enzyme did not account for the genetic susceptibility to ras activation. CONCLUSIONS: The results indicate that there is a clear strain and carcinogen dependency of K-ras mutation and that the frequency of ras mutation might determine the genetic susceptibility to ENU-induced lymphomagenesis, whereas pathways independent of ras activation might determine the susceptibility to X-ray-induced lymphomagenesis.     

骨关节病关节软骨细胞线粒体DNA突变检测

目的 :探讨线粒体DNA突变在退行性疾病骨关节病发病中的意义。方法 :采用PCR -SSCP技术 ,结合线粒体DNA测序方法 ,检测了 8例骨关节病和 3例正常人的关节软骨细胞线粒体DNA在一个特点区域 (np:80 0 0— 90 0 0 )内的突变改变。结果 :在 8例骨关节病例中 ,有 4例出现了线粒体DNA突变 (不包含中性突变 ) ,其中单有点突变并导致氨基酸发生改变的有 2例 ,单有缺失突变的有 1例 ,既有点突变又有缺失突变的有 1例 ;此外 ,发现中性突变 (不改变氨基酸 )的有 4例 ;1例正常标本发现有线粒体DNA点突变存在 ;所有进行了DNA测序检测的标本均发现线粒体DNA886 0位点AG的突变。结论 :骨关节病与线粒体DNA突变有密切关系 ,但其因果关系尚待进一步研究。     

Factor V Leiden, FII G20210A, MTHFR C677T mutations as risk factors for venous thrombosis during pregnancy and puerperium

BACKGROUND: Venous thrombosis is the most common cause of obstetric morbidity and mortality during pregnancy and puerperium. The incidence of pregnancy-associated venous thrombosis varies from 1 in 1000 to 1 in 2000 deliveries. Factor V G1691A (FV Leiden), FII G20210A and MTHFR C677T mutations are the most common genetic risk factors for thromboembolism. The aim of this study was to establish the presence of these risk factors in a group of women with an episode of deep venous thrombosis during pregnancy or puerperium. METHODS: The study was carried in a group of 45 women with the first episode of deep venous thrombosis during pregnancy or puerperium. The patients with antiphospholipid antibodies, antithrombin III, protein C or protein S deficiency, and autoimmune and malignant diseases were excluded from the study. FV Leiden, FII G20210A, and MTHFR C677T mutations were detected by polymerase chain reaction, followed by digestion with specific restriction enzymes. RESULTS: Twenty heterozygous carriers of the FV Leiden mutation and one homozygous carrier were detected, which represents the frequencies of 44.4% and 2.2%, respectively. For the FII G20210A mutation, six heterozygous carriers were identified, giving the frequency of 13.3%. The MTHFR C677T mutation was observed in 31 patients (22 heterozygous and 9 homozygous carriers) which represents the frequencies of 48.9% and 20%, respectively. CONCLUSION: Our study suggested that the obligatory testing for FV Leiden and FII G20210A mutations was strongly recommended in women with history of venous thrombosis during pregnancy and puerperium. We found a slight effect of MTHFR 677T allele, but it should be considered in association with other risk factors.     

新生儿线粒体12S rRNA基因筛查对预防药物性耳聋的价值

目的 通过对新生儿线粒体12S rRNA基因突变的检测,探讨线粒体耳聋基因筛查的必要性和可行性。方法 对2018-12至2021-10在石家庄市第四医院出生的46 376例新生儿采用荧光定量PCR检测技术进行线粒体12S rRNA检测,检测突变位点为A1555G和C1494,对结果阳性新生儿进行预防接种随访。结果 46 376例新生儿线粒体12S rRNA检测结果中共发现突变94例,突变携带率为0.20%。其中,A1555G均质突变76例,异质突变14例,其中1例异质突变为新发;C1494T均质突变3例,异质突变1例。完成随访88例,随访年龄5～32月龄,78例(88.64%)幼儿按月龄常规接种疫苗,10例接种部分疫苗,正常接种率88.64%,与未携带者对比差异存在统计学意义(P<0.01)。结论 进行线粒体12S rRNA基因筛查可以在早期发现氨基糖苷类抗生素敏感个体,避免药物性聋的发生。     

Hereditary thrombophilia in elite athletes

PURPOSE: Although under normal circumstances exercise prevents thrombosis, there are cases in the literature that indicate a connection between exercise and the onset of thrombosis. In the average population, hereditary thrombophilia is a major cause of thrombosis. However, nothing is known about the prevalence of hereditary thrombophilia in elite athletes. Because high-performance sports are known to carry an increased risk of thrombogenesis, measures to avoid thrombosis must be initiated in cases of known hereditary thrombophilia. METHODS: Hereditary thrombophilia was checked for in 173 elite athletes, members of the German national team. Antithrombin III, protein C, protein S, and the APC ratio, followed by a molecular genetic analysis, were measured, and molecular analysis of factor II G20210A mutation was used to detect the presence of an antithrombin III-, protein C- and protein S-deficiency, as well as factor V Leiden (factor V 506Arg to Gln) and factor II G20210A mutation. RESULTS: No definite antithrombin III-, protein C- or protein S-deficiency was found. In 12 cases, an APC resistance caused by a factor V Leiden mutation (11 heterozygous; 1 homozygous) was detected. In 10 cases, a heterozygous factor II G20210A was observed; a combination of both mutations was not found. For factor V Leiden, this corresponds to a prevalence of 6.9% (CI 95% 3.6-11.8%) in our group, similar to prevalence rates in the general population. Additionally, the observed prevalence of 5.8% (CI 95% 2.8-10.4%) of factor II G20210A is nearly within the range as reported by several authors. CONCLUSION: Based on the observed prevalence of APC resistance and factor II G20210A mutation in our group of athletes, along with consideration of additional circumstantial risks, screening tests for elite athletes should be considered to allow the undertaking of preventive measures.     

Detection of T to G mutation at position 59 in the Lewis gene by mismatch polymerase chain reaction

Recently, we discovered the missense mutations of T to G at position 59 and of G to A at position 508 in one of the Lewis-negative (le) genes (Koda et al. 1993). In the present study, we report a method to detect the mutation at position 59 using mismatch PCR amplification and endonucleaseMspI digestion. For this mutation, we found that 7 out of 12 Lewis-negative, and none of 15 Lewis-positive individuals were homozygous, while 4 out of 12 Lewis-negative, and 4 out of 15 Lewis-positive individuals were heterozygous. These results indicate that the mutation at position 59 is a common mutation in thele genes.     

Mutagenic effects of 5-formyluracil on a plasmid vector during replication in Escherichia coli

PURPOSE: 5-Formyluracil (5-foU) is a major derivative of thymine produced in DNA by ionizing radiation and various chemical oxidants. It has been previously shown that 5-foU in template DNA directs misincorporation of nucleotides by DNA polymerases during in vitro DNA synthesis. The present experiments were designed to understand the biological effects of5-foU in vivo. MATERIALS AND METHODS: The modified base was incorporated site-specifically into the recognition site of restriction endonuclease SalI (5'-GTCGAC) or AflII (5'-CTTAAG) in vector plasmid pSVK3 and introduced the plasmid into Escherichia coli. RESULTS: When the plasmids were replicated in E. coli, 5-foU caused mutations at the target sites. The induced mutation frequencies were 0.038-0.049%. Sequence analysis revealed that 5-foU preferentially caused T:A-->C:G and T:A-->A:T base substitutions and -1 deletions at the 5-foU site. 5-FoU also caused mutations at sites near the 5-foU. The alkA mutation did not affect the frequency of mutations in 5-foU-containing plasmids. CONCLUSIONS: The present experiments demonstrated that 5-formyluracil in DNA caused mutations in E. coli.     

Mutagenic effects of 5-formyluracil on a plasmid vector during replication in Escherichia coli

Purpose : 5-Formyluracil (5-foU) is a major derivative of thymine produced in DNA by ionizing radiation and various chemical oxidants. It has been previously shown that 5-foU in template DNA directs misincorporation of nucleotides by DNA polymerases during in vitro DNA synthesis. The present experiments were designed to understand the biological effects of 5-foU in vivo. Materials and methods : The modified base was incorporated site-specifically into the recognition site of restriction endonuclease Sal I (5'-GTCGAC) or Afl II (5'-CTTAAG) in vector plasmid pSVK3 and introduced the plasmid into Escherichia coli. Results : When the plasmids were replicated in E. coli, 5-foU caused mutations at the target sites. The induced mutation frequencies were 0.038-0.049%. Sequence analysis revealed that 5-foU preferentially caused T:A →C:G and T:A →A:T base substitutions and -1 deletions at the 5-foU site. 5-FoU also caused mutations at sites near the 5-foU. The alkA mutation did not affect the frequency of mutations in 5-foU-containing plasmids. Conclusions : The present experiments demonstrated that 5-formyluracil in DNA caused mutations in E. coli.     

Genetic susceptibility to thymic lymphomas and K‐ras gene mutation in mice after exposure to X‐rays and N‐ethyl‐N‐nitrosourea

Purpose: Ras activation is one of the major mechanisms for the development of murine thymic lymphomas by radiation and chemical carcinogens. To gain insight into the relationship between genetic susceptibility and ras gene mutation, the frequency and spectrum of ras gene mutation was examined in thymic lymphomas from susceptible and resistant mice.

Materials and methods: K‐ and N‐ras mutations in thymic lymphomas that arose in X‐ray‐irradiated and N‐ethyl‐N‐nitrosourea (ENU)‐treated mice of susceptible C57BL/6, rather resistant C3H and their hybrid B6C3F1 were analysed by polymerase chain reaction‐single‐strand conformation polymorphism and subsequent DNA sequencing.

Results: C57BL/6 exhibited a higher incidence of thymic lymphomas after exposure to X‐rays and ENU than C3H, with B6C3F1 being intermediate. K‐ras gene mutations occurred frequently in the pathogenesis of ENU‐induced thymic lymphomas in susceptible C57BL/6 as opposed to resistant C3H. The ras mutations were more frequent in ENU‐induced thymic lymphomas than X‐ray‐induced thymic lymphomas, and with the latter, there was no clear evidence for strain differences, suggesting that the genetic susceptibility to X‐rays was independent of ras activation. The mutations of K‐ras in thymic lymphomas from C57BL/6 were predominantly GGT to GAT in codon 12, whereas this mutation type was never found in those from C3H. No strain difference was observed in the nucleotide sequence or expression levels of O⁶‐alkylguanine alkyltransferase, indicating that this enzyme did not account for the genetic susceptibility to ras activation.

Conclusions: The results indicate that there is a clear strain and carcinogen dependency of K‐ras mutation and that the frequency of ras mutation might determine the genetic susceptibility to ENU‐induced lymphomagenesis, whereas pathways independent of ras activation might determine the susceptibility to X‐ray‐induced lymphomagenesis.     

Detection of age-related duplications in mtDNA from human muscles and bones

Several studies have demonstrated the age-related accumulation of duplications in the D-loop of mitochondrial DNA (mtDNA) extracted from skeletal muscle. This kind of mutation had not yet been studied in bone. The detection of age-related mutations in bone tissue could help to estimate age at death within the context of legal medicine or/and anthropological identification procedures, when traditional osteological markers studied are absent or inefficient. As we detected an accumulation of a point mutation in mtDNA from an older individual’s bones in a previous study, we tried here to identify if three reported duplications (150, 190, 260 bp) accumulate in this type of tissue. We developed a sensitive method which consists in the use of back-to-back primers during amplification followed by an electrophoresis capillary analysis. The aim of this study was to confirm that at least one duplication appears systematically in muscle tissue after the age of 20 and to evaluate the duplication age appearance in bones extracted from the same individuals. We found that the number of duplications increase from 38 years and that at least one duplicated fragment is present in 50% of cases after 70 years in this tissue. These results confirm that several age-related mutations can be detected in the D-loop of mtDNA and open the way for the use of molecular markers for age estimation in forensic and/or anthropological identification.     

Chromosomal radiosensitivity in BRCA1 and BRCA2 mutation carriers

PURPOSE: The chromosomal radiosensitivity of a selected group of familial breast cancer patients carrying a mutation in BRCA1 (n=11) or BRCA2 (n=9) and a group of healthy mutation carriers (n=12) was investigated and compared to a reference group of breast cancer patients without a BRCA1/2 mutation (n=78) and a group of healthy women carrying no mutation (n=58). MATERIALS AND METHODS: The chromosomal radiosensitivity was assessed with the G2 and the G0-micronucleus (MN)-assay on fresh blood samples and on Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines. For the MN-assay, lymphocytes were exposed in vitro to 3.5 Gy and 2 Gy 60Co gamma-rays at a high dose rate (HDR) or low dose rate (LDR). 70-h post-irradiation cultures were arrested and micronuclei were scored in 1000 binucleate cells. For the G2-assay lymphocytes were irradiated in vitro with a dose of 0.4 Gy 60Co gamma-rays after 71h incubation. Cultures were arrested 90 min after irradiation and chromatid breaks were scored in 50 metaphases. RESULTS: The group of breast cancer patients with a BRCA1 or 2 mutation was on average more radiosensitive than the control group, but not different from breast cancer patients without a BRCA mutation. The radiation response of healthy BRCA1/2 carriers was not significantly different from the control group and also not different from relatives without a BRCA mutation. Comparing the radiation response in EBV cell lines derived from breast cancer patients with or without a BRCA1 mutation revealed no significant difference. CONCLUSIONS: Our results reveal that chromosomal radiosensitivity observed in breast cancer patients heterozygous for BRCA1 or 2 mutations, could not be demonstrated in healthy BRCA1/2 mutation carriers. This suggests that mutations in BRCA1 or 2 genes are not playing a main role in chromosomal radiosensitivity, this although BRCA1 and 2 are both involved in DNA repair/signalling processes.     

Mutations caused by gamma-radiation-induced double-strand breaks in a shuttle plasmid replicated in human lymphoblasts.

The mutagenicity of open-circular DNA (containing base damage and single-strand breaks) and linear DNA (containing base damage, single-strand breaks, and one double-strand break) produced in vitro by gamma-irradiation of shuttle vector pZ189, was analysed after the plasmid's repair and replication in the human lymphoblast line, GM606. By comparing the survival, mutation frequency, and types of mutations in descendants from the two DNA forms, the effects of the double-strand break were determined. The percentage of viable plasmids from linear DNA was two-fold lower than that from open-circular DNA, 7.8 versus 14.0 (compared with unirradiated, control DNA). The mutation frequency in progenies of the open-circular plasmid was 4.2 +/- 1.7 x 10(-3), compared with 7.8 +/- 0.1 x 10(-3) in progenies of the linear DNA, again, nearly a two-fold difference. Approximately 59% of the mutations from the linear DNA were deletions and 34% were base substitutions. In contrast, only 13% of mutations from open-circular DNA were deletions, but 87% were base substitutions. All recoverable deletions were small, ranging from 1 to 205 base pairs, and the majority contained direct repeats at the deletion junctions, indicating non-homologous recombinations. Thus, mutations found among descendants from the linear and open-circular DNAs were qualitatively similar but quantitatively different. The data suggests that producing one double-strand break in DNA by ionizing radiation causes a two-fold increase in both lethality and mutation frequency.     

Characteristic association between K-ras gene mutation with loss of heterozygosity in X-ray-induced thymic lymphomas of the B6C3F1 mouse

PURPOSE: To elucidate the characteristics of radiation carcinogenesis, the spectra of K- and N-ras oncogene mutations, loss of heterozygosity (LOH) and their association in X-ray-induced thymic lymphomas (TL) were determined by comparing with those of N-ethyl-N-nitrosourea (ENU)-induced and spontaneously occurring TL. MATERIALS AND METHODS: TL that arose in untreated, X-ray-irradiated and ENU-treated B6C3F1 mice were examined both for K- and N-ras mutations by PCR-SSCP and DNA sequencing and for LOH by PCR with polymorphic microsatellite markers. RESULTS: (1) ras gene mutations were found in a proportion of TL from X-ray-exposed (approximately 20%) and ENU-treated (30-40%) mice while no ras gene mutations were found in spontaneous TL. N-ras mutations were rare. (2) The spectrum of ras gene mutations was diverse and seemed to differ little between X-ray-induced and ENU-induced TL, even though there was a higher frequency of ras mutations in ENU-induced TL that clustered to K-ras codon 12. (3) The X-ray-induced TL showing K-ras mutation were associated with LOH on chromosome 6, while those showing no K-ras mutation were associated with high frequency of LOH on chromosomes 4, 11 and 12. CONCLUSION: These results demonstrate that, in the B6C3F1 mouse TL, X-ray-induced lymphomagenesis showed both the co-expression, yet low occurrence of allelic imbalance on chromosome 6 and K-ras mutation, and exclusive expression of frequent allelic imbalance on chromosomes 4, 11 and 12 and K-ras mutation.     

Characteristic association between K- ras gene mutation with loss of heterozygosity in X-ray-induced thymic lymphomas of the B6C3F1 mouse

Purpose : To elucidate the characteristics of radiation carcinogenesis, the spectra of K- and N- ras oncogene mutations, loss of heterozygosity (LOH) and their association in X-ray-induced thymic lymphomas (TL) were determined by comparing with those of N -ethyl- N -nitrosourea (ENU)-induced and spontaneously occurring TL. Materials and methods : TL that arose in untreated, X-ray-irradiated and ENU-treated B6C3F1 mice were examined both for K- and N- ras mutations by PCR-SSCP and DNA sequencing and for LOH by PCR with polymorphic microsatellite markers. Results : (1) ras gene mutations were found in a proportion of TL from X-ray-exposed (~20%) and ENU-treated (30-40%) mice while no ras gene mutations were found in spontaneous TL. N- ras mutations were rare. (2) The spectrum of ras gene mutations was diverse and seemed to differ little between X-ray-induced and ENU-induced TL, even though there was a higher frequency of ras mutations in ENU-induced TL that clustered to K- ras codon 12. (3) The X-ray-induced TL showing K- ras mutation were associated with LOH on chromosome 6, while those showing no K- ras mutation were associated with high frequency of LOH on chromosomes 4, 11 and 12. Conclusion : These results demonstrate that, in the B6C3F1 mouse TL, X-ray-induced lymphomagenesis showed both the co-expression, yet low occurrence of allelic imbalance on chromosome 6 and K- ras mutation, and exclusive expression of frequent allelic imbalance on chromosomes 4, 11 and 12 and K- ras mutation.     

Multiple recurrent mutations at four human Y-chromosomal single nucleotide polymorphism sites in a 37 bp sequence tract on the ARSDP1 pseudogene

The male-specific region of the human Y chromosome (MSY) is passed down clonally from father to son and mutation is the single driving force for Y-chromosomal diversification. The geographical distribution of MSY variation is non-random. Therefore, Y-chromosomal single nucleotide polymorphisms (Y-SNPs) are of forensic interest, as they can be utilized, e.g. for deducing the bio-geographical origin of biological evidence. This extra information can complement short tandem repeat data in criminal investigations. For forensic applications, however, any targeted marker has to be unequivocally interpretable.Here, we report findings for 17 samples from a population study comprising specimens from ∼3700 men living in Tyrol (Austria), indicating apparent homoplasic mutations at four Y-SNP loci on haplogroup R-M412/L51/S167, R-U152/S28, and L-M20 Y chromosomes. The affected Y-SNPs P41, P37, L202, and L203 mapped to a 37 bp region on Yq11.21. Observing in multiple phylogenetic contexts up to four homoplasic mutations within such a short sequence tract is unlikely to result from a series of independent parallel mutations. Hence, we rather propose X-to-Y gene conversion as a more likely scenario.Practical implications arising from markers exhibiting paralogues on the Y chromosome or sites with a high propensity to recurrent mutation for database searches are addressed.     

军事噪声性听力损失的线粒体基因变异分析

目的研究线粒体基因变异与军事噪声性听力损失遗传易感性的关系,为确定噪声易感个体的分子诊断方法提供依据。方法对云南某部接触军事噪声的406名坦克兵、626名炮兵共计1032例进行听力损失调查,收集军事噪声易感者(易感组)82例,耐受者(耐受组)40例,共计122例。分别采集外周静脉血标本,从白细胞中提取DNA,PCR扩增线粒体DNA及非综合征型耳聋相关的热点突变部分片段,进行基因测序比对分析,比较两组中存在碱基改变的位点分布例数。对测序结果中存在与耳聋相关的碱基改变的个体做进一步的听力学分析。结果军事噪声易感者和耐受者的线粒体基因存在一定差异,线粒体COII基因T7684C和G7853A两个位点的变化只存在于易感组,两组间有显著性差异(P<0.05)。A827G、T961insC(异质)、T1005C、T1095C、G7444A等可能与耳聋相关的线粒体基因改变多见于易感组,耐受组也有分布。结论携带线粒体COII基因T7684C和G7853A碱基变化的个体可能对军事噪声更加易感。     

Y-chromosomal microsatellite mutation rates in a population sample from northwestern Germany

To estimate Y-chromosomal short tandem repeat (Y-STR) mutation rates, 15 loci (i.e., DYS19, DYS389 I/II, DYS390, and DYS393; DYS437, DYS438, DYS439, and DYS385; DYS391, DYS392, YCA II, and DXYS156) were analyzed in a sample of 1,029 father/son pairs from Westphalia, northwestern Germany. Among 15,435 meiotic allele transfers, 32 mutations were observed; thus, the mutation rate across all 15 Y-STR loci was 2.1 × 10⁻³ per locus (95% C.I.: 1.5–3.0 × 10⁻³). With the exception of a three-repeat mutation at DYS385, all remaining mutations were single repeat mutations. Repeat losses were more frequent than gains (20:12), and the mutation rate appeared to increase with age. The Y haplogroups that were detected in the individuals showing a mutation reflect the haplogroup distribution in the Westphalian population. Additionally, the correlation of surnames and haplotypes was tested: Only 49 surnames occurred more than once, and only two men with the same rare surname shared the same haplotype. All other men with identical surnames carried different haplotypes. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

食管反流大鼠肿瘤诱发过程中p53基因突变的研究

通过动物实验研究不同反流状态下食管肿瘤诱发过程中 p5 3基因的突变情况。选用SD大鼠进行不同手术 ,制作单纯胃食管反流 (G组 )、单纯十二指肠食管反流 (D组 )、胃十二指肠混合液食管反流 (DG组 )及无反流对照 (C组 )模型 ,于术后 4周开始注射食管致癌剂甲基戊基亚硝胺 (MANA) ,共 15周 ,于术后 2 0、2 6、40周分批取得食管组织 ,进行基因组DNA抽提 ,合成 p5 3基因的第 5、6、7、8外显子的 4对引物 ,进行PCR扩增。扩增产物变性后进行非变性聚丙烯酰胺凝胶电泳 (PCR SSCP) ,电泳后凝胶以硝酸银染色。结果显示PCR扩增未见 p5 3基因缺失。 2 0周时D组及DG组各有 1只 (10 % )标本检测出p5 3突变。此后随时间延长各组突变增加 ,40周时D组 (31 6 % )、DG组 (33 3 % )的突变率显著高于C组 (15 4% )和G组 (11 7% ) ,P均 <0 0 5 ,后两者差异无显著性意义 (P >0 0 5 )。提示十二指肠内容物食管反流可导致食管粘膜上皮p5 3基因的突变率增加 ,这可能是它促进食管肿瘤发生的机制之一。而单纯胃液反流不增加食管的 p5 3基因突变