Standardized molecular typing of Candida albicans strains

Summary. A method is presented for the standardization of Candida albicans DNA fingerprinting, which is based on Southern hybridization of Eco RI-digested chromosomal DNA with the moderately repetitive DNA element CARE-2 and the subsequent rehybridization of the blots with a molecular size marker also included in each DNA sample. This method resulted in extremely precise alignment of all strain-specific CARE-2 hybridization patterns, even when analysed on different gels, and will enhance the accuracy of genetic relationship determinations in epidemiological studies including large numbers of strains.
Zusammenfassung. Zur Standardisierung des DNA-Fingerprinting von Candida albicans wurde eine Methode entwickelt, die auf der Southern Hybridisierung Eco RI-gespaltener chromosomaler DNA mit dem mittelrepetitiven DNA-Element CARE-2 und der darauffolgenden Rehybridisierung der Blots mit einem auch in den Proben enthaltenen molekularen Größenmarker beruht. Dies resultierte in einer äußerst präzisen Größen-bestimmung der hybridisierenden Fragmente, so daß alle stammspezifischen CARE-2-Hybridisierungsmuster exakt verglichen werden konnten, auch wenn die Isolate auf verschiedenen Gelen analysiert wurden. Die Methode erhöht die Genauigkeit der Bestimmung genetischer Verwandtschaftsbeziehungen in epidemiologischen Untersuchungen, in denen eine große Anzahl von Stämmen analysiert wird.     

Genetic analysis of the yeast NUD1 endo-exonuclease: a role in the repair of DNA double-strand breaks

The deoxyribonucleases (DNases) have been shown genetically to be important in the vital processes of DNA repair and recombination. The NUD1 gene, which codes for an endo-exonuclease of Saccharomyces cerevisiae, was analyzed for its role in the DNA double-strand break (DSB) repair processes. While the nud1 strain is only slightly sensitive to ionizing radiation, expression of the HO-endonuclease to introduce a DSB at the MAT locus in that strain results in cell death. Cell survival is inversely proportional to the duration of HO-endonuclease expression. Analysis of the surviving colonies from the nud1 strain indicated that many of the survivors are sterile and that the proportion of these sterile survivors increases with the time of HO-endonuclease expression. On the other hand, the surviving colonies from the isogenic NUD1 strain are mating-proficient. Interestingly, double mutants of nud1 rad52 are more resistant to ionizing irradiation than the rad52 strain and have a cell-survival fraction of 32% for rad52-1 nud1 and 9% for rad52::URA3 nud1 following prolonged HO-endonuclease expression, indicating that nud1 has a suppressor effect on the DSB-induced lethality in rad52. Polymerase chain reaction analysis showed that many of the nud1 survivors contained small alterations within the MAT locus, suggesting that the survivors arose through the process of non-homologous end-joining. These results suggest that the endo-exonuclease acts at a DSB to promote DNA repair via the homologous recombination pathway. Received: 20 July / 20 September 1998     

DNA flow cytometry in stage IB and II cervical carcinoma

In a retrospective study the prognostic significance of nuclear DNA content was investigated, as measured by flow cytometry, of the tumor specimens from 212 women with nonpretreated FIGO stage IB and II cervical cancer. One-hundred and thirty cases (62%) were found to be diploid, whereas 82 (38%) were aneuploid. Univariate analysis of the follow-up data showed an increased relative risk (RR) for recurrence free survival (RFS) for stage II tumors (RR = 1.87, 95% CI: 1.13–3.10, P = 0.015) and for age (RR = 1.52, 95% CI: 0.66–3.52 and RR = 2.35, 95% CI: 1.19–4.65, P = 0.032). Ploidy showed a relative risk of 1.33 (95% CI: 0.83–2.13, NS). In addition, univariate analysis of overall survival (OS) revealed similar results. For the subgroup of patients with primary surgery ( n = 151), positive pelvic nodes (RR = 5.38, 95% CI: 2.70–10.71, P = 0.0001) and parametrial extension (RR = 2.53, 95% CI: 1.24–5.17, P = 0.011) were significant factors for OS after univariate analysis, the estimated effects on RFS were slightly smaller. Multivariate analysis of RFS for the whole study population showed age, histologic grade and stage with a slightly increased risk, but no effect was significant. Ploidy with an RR of 0.97 (95% CI: 0.58–1.62) seems to have no influence on prognosis. For the subgroup with primary surgery, ploidy again failed statistical significance with an RR of 1.20 (95% CI: 0.58–2.49). Our results suggest that abnormalities of the nuclear DNA content in this homogeneous group of patients are associated with clinical and morphological prognosticators, however, ploidy is not an independent prognostic factor for RFS, or for the whole study population or for the subgroup with primary surgery.     

Study on the Relationship between Cytogenetics and Phenotypic Effect in Turner＇s Syndrome

ＳｔｕｄｙｏｎｔｈｅＲｅｌａｔｉｏｎｓｈｉｐｂｅｔｗｅｅｎＣｙｔｏｇｅｎｅｔｉｃｓａｎｄＰｈｅｎｏｔｙｐｉｃＥｆｆｅｃｔｉｎＴｕｒｎｅｒ＇ｓＳｙｎｄｒｏｍｅＨＵＸｉａｏｆｅｎｇ（胡晓峰）；ＺＨＵＢａｏｓｈｅｎｇ（朱宝生）；ＬＩＮＨａｎｈｕａ（林汉华）...     

Genomic DNA fingerprints and phenotypic characteristics of serotype B Haemophilus influenzae isolates from Italy

Three different restriction enzymes (PstI, EcoRI, SspI) were used to analyze the total genomic DNA fingerprints of 52 Haemophilus influenzae type b (Hib) isolates collected between 1982 and 1992 from patients and carriers in central-northern Italy. The same isolates were also characterized by biotyping and antimicrobial agent susceptibility typing. In addition, 13 Hib reference strains from Sweden and the Netherlands were subjected to DNA fingerprinting and compared to Italian isolates.Both genotypic and phenotypic analysis revealed low variability among the Italian study isolates. Most were biotype I and all study isolates but one were susceptible to ampicillin, chloramphenicol, rifampin, third-generation cephalosporins and cotrimoxazole. Among the 52 Italian isolates, 3 distinct DNA patterns were identified, and 88.5% of study strains belonged to the same DNA group. There was sharing of the predominant DNA profile among isolates cultured in different years from different geographical areas and different invasive, respiratory and surface infections. However, another DNA pattern was only found in carrier isolates and in one surface infection isolate.Comparison by DNA fingerprinting showed that the majority of Italian isolates were closely related to most of the analyzed Swedish and Dutch reference strains, previously shown by other techniques to be predominant in those areas. This finding provides additional support for the hypothesis that there may be a dominant European Hib clone.The results show that DNA fingerprinting is a reliable method for Hib characterization and may be a useful additional epidemiological tool for this microorganism.     

Nephron Sparing Surgery for De Novo Renal Cell Carcinoma in an Allograft Kidney: A Case Report

De novo renal cell carcinoma in a renal allograft is rare and has special implications in renal transplant recipients. We describe a patient with a renal allograft who developed a de novo renal cell carcinoma in the functioning renal allograft 258 months after transplantation. The patient underwent enucleation of the tumor because preoperative MRI showed it was well-encapsulated. A DNA banding study showed that the tumor originated from the donor. Indications for conservative renal surgery in renal cell carcinoma have been increasing. Accordingly, 1 option in the treatment of de novo renal cell carcinoma in a functioning renal allograft is enucleation as a method of nephron sparing surgery.     

Unusual presentation and clinical variability in Belgian pedigrees with progressive external ophthalmoplegia and multiple deletions of mitochondrial DNA

We studied 14 patients from three unrelated Belgian pedigrees with a familial mitochondrial disorder and multiple deletions of mitochondrial DNA (mtDNA). In one family with an oculopharyngeal presentation there is a clear autosomal dominant inheritance. Progressive external ophthalmoplegia (PEO), “ragged red fibres” (RRF) and multiple deletions of mtDNA are common to all three families. Therefore a diagnosis of autosomal dominant progressive ophthalmoplegia with multiple deletions of mtDNA (adPEO) was made in one family at least. Our data confirm the previous observations that adPEO is a systemic disorder rather than a pure myopathy. In our pedigrees frequently associated features include axonal peripheral neuropathy, dysphagia, psychiatric illness, and sudden death. Mild ataxia, pes cavus and mitral valve prolapse with associated mitral insufficiency also occur. In some cases onset is atypical with neuropathy, adolescent onset myopathy or psychiatric illness. In such cases the common features of PEO and muscle weakness always complete the clinical phenotype later during the course of the disease. Biochemical studies on mitochondrial fractions prepared from one patient's muscle, revealed no abnormalities of respiratory chain enzyme activities.     

环氧化酶-2基因启动子甲基化及表达与胃黏膜病变的关系

目的 探讨环氧化酶2(COX-2)基因启动子区甲基化水平和蛋白表达与胃黏膜病变的关系,并对其相关的影响因素进行研究.方法 以1201例患有不同胃黏膜病变的高危人群为研究对象,采用免疫组织化学方法榆测COX-2表达,用亚硫酸氢钠-变性高效液相色谱(DHPLC)对COX-2启动子甲基化率进行定量分析,采用13C尿素呼气实验(13C-UBT)对幽门螺旋杆菌(H priori)感染状况进行测定.结果 COX-2甲基化率中位数随胃黏膜病变的加重逐渐升高,在浅表性胃炎和慢性萎缩性胃炎(SG/CAG)、肠上皮化生(IM)及不确定性异型增生和异璎增生(Ind DYS/DYS)病变中分别为10.6%、11.8%、13.8%,各病变组之间差异有统计学意义(X2=8.312,P=0.016).分层分析显示,在H pylori感染阴性病例中,COX-2甲基化率仍随病变加重明显升高,在SG/CAG、IM、Ind DYS/DYS病变中其中位数分别为8.8%、10.6%、14.1%(X2=6.629,P=0.036).进一步分析发现,COX-2甲基化率随着COX-2表达强度的增强而降低,由COX-2弱阳性表达的13.3%降至强阳性表达的7.6%(X2=10.400,P=0.015).结论 COX-2启动子甲基化水平与胃黏膜病变程度及H pylori感染状况密切相关,并与COX-2表达强度呈负相关,说明COX-2启动子区异常甲基化可能在胃黏膜病变的演变过程中起重要作用.     

A nuclear mutant of Chlamydomonas that exhibits increased sensitivity to UV irradiation,reduced recombination of nuclear genes,and altered transmission of chloroplast genes

Summary Meiotic progeny of Chlamydomonas reinhardtii normally receive chloroplast genomes only from the mt ⁺ parent. However, exceptional zygotes, which transmit the chloroplast genomes of both parents or, more rarely, only those of the mt ^- parent, arise at a low frequency. Mutations at the mt ⁺-linked mat-3 locus were found previously to elevate the transmission of chloroplast genomes from the mt-parent, resulting in a much higher than normal frequency of exceptional zygotes. In this paper we demonstrate that an ultraviolet-sensitive nuclear mutation mapping at the uvsE1 locus, which is unlinked to mating type, also promotes chloroplast genome transmission from the mt ^- parent. This mutant, which was previously shown to reduce recombination of nuclear genes in meiosis, acts synergistically which the mat3-3 mutation to produce an extremely high frequency of exceptional zygotes. Through the use of restriction fragment length polymorphisms existing in the chloroplast genomes of C. reinhardtii and the interfertile strain C. smithii, we show that chloroplast DNA fragments from the mt ^- parent normally begin to disappear shortly after zygote formation. However, this process appears to be blocked totally in the absence of wild-type uvsE1 and mat-3 gene products. Our findings are consistent with the hypothesis that both gene products contribute to the mechanism responsible for uniparental inheritance of the chloroplast genome from the mt ⁺ parent.     

赖型钩体flaB2与VR1012中的CpG基序分析

目的：对问号赖型钩端螺旋体（赖型钩体）DNA疫苗[包括内鞭毛蛋白基因（flaB2)和质粒DNA表达载体（VR1012）]的CpG基序（CpG motifs)进行分析，为DNA疫苗免疫机制的阐明和提高DNA疫苗的效能奠定基础。方法：以flaB2与VR1012构建重组DNA的免疫原，对flaB2及VR1012全核苷酸序列进行计算机分析（分类、计数和定位）。结果：CpG的“C”的侧翼为两个嘌呤，“G”的侧翼为两个嘧啶，在flaB2中共3个，分别为GACGCT，GACGTC和GACGCC；在VR1012中共11个，分别为GACGTC1个，GACGCT2个，GACGCC1个，GACGTT1个，GGCGTT2个，GGCGCT2个，GGCGCC1个，AACGCT1个，其中特别重要的TGACGTCA4个和TAACGCCA有1个，位于5'端456－463；509－516；592－599；778－785和486－493；4个TGACGTCA和1个TAACGCCA均位于5'端且相对集中。结论：赖型钩体flaB2与VR1012构成的DNA疫苗含有TGACGTCA等CpG，这些基序又称免疫刺激序列，构成了DNA疫苗中的佐剂。