The specific mitochondrial DNA polymorphism found in Klinefelter's syndrome

Hypervariable segments of mitochondrial DNA (mtDNA) (HV1 and HV2) were analyzed in Klinefelter's syndrome and compared to normal population data. One pair of samples consisting of a Japanese mother and affected son with Klinefelter's syndrome (involved in a criminal case), and seven unrelated DNA samples from Caucasian Klinefelter males (two involved in criminal cases and five diagnosed) were collected in Japan and the United States. The diagnosis of Klinefelter's syndrome was established previously by multiplex XY-STR typing detecting two X alleles and one Y allele in the samples. Haplotype analysis of the mtDNA sequence in Klinefelter males was found to be identical, unique, and specific, as it was not found in the normal population. Astonishingly, family data exhibited that the haplotype of the mtDNA in the son was apparently different from the mother's, suggesting that the mtDNA of Klinefelter male would not be inherited from mother to son. Our data indicate that possible interaction of the sex chromosome and the mtDNA exists, and suggests that the specific mtDNA haplotype could cause the abnormal cell to fertilize and reproduce itself.     

The plant homeodomain finger protein MESR4 is essential for embryonic development in Drosophila

Misexpression Suppressor of Ras 4 (MESR4), a plant homeodomain (PHD) finger protein with nine zinc‐finger motifs has been implicated in various biological processes including the regulation of fat storage and innate immunity in Drosophila. However, the role of MESR4 in the context of development remains unclear. Here it is shown that MESR4 is a nuclear protein essential for embryonic development. Immunostaining of polytene chromosomes using anti‐MESR4 antibody revealed that MESR4 binds to numerous bands along the chromosome arms. The most intense signal was detected at the 39E‐F region, which is known to contain the histone gene cluster. P‐element insertions in the MESR4 locus, which were homozygous lethal during embryogenesis with defects in ventral ectoderm formation and head encapsulation was identified. In the mutant embryos, expression of Fasciclin 3 (Fas3), an EGFR signal target gene was greatly reduced, and the level of EGFR signal‐dependent double phosphorylated ERK (dp‐ERK) remained low. However, in the context of wing vein formation, genetic interaction experiments suggested that MESR4 is involved in the EGFR signaling as a negative regulator. These results suggested that MESR4 is a novel chromatin‐binding protein required for proper expression of genes including those regulated by the EGFR signaling pathway during development. genesis 53:701–708, 2015. © 2015 Wiley Periodicals, Inc.     

PCR及其衍生技术在基因突变检测中的应用

许多人类遗传性疾病及某些抗艾滋病药物的抗性乃至细菌对某些抗生素的抗药性通常源于基因突变。本文对近年来在基因突变检测中应用日益广泛的各种PCR 衍生技术作一综述;重点介绍了错配PCR技术,以及我们实验室近期报道的一种快速检测喹诺酮类药物耐药大肠杆菌的错配PCR方案。 Abstract:Many inherited diseases and drug resistance have been attributed to mutations in corresponding genes.In this paper,several techniques based on PCR used in diagnosis were concluded.The development and research progress of Mismatch PCR were discussed in details.Some information about an assay that we developed for detection of antimicrobial resistance to quinolones was also described.     

DNA replication and strand asymmetry in prokaryotic and mitochondrial genomes

Different patterns of strand asymmetry have been documented in a variety of prokaryotic genomes as well as mitochondrial genomes. Because different replication mechanisms often lead to different patterns of strand asymmetry, much can be learned of replication mechanisms by examining strand asymmetry. Here I summarize the diverse patterns of strand asymmetry among different taxonomic groups to suggest that (1) the single-origin replication may not be universal among bacterial species as the endosymbionts Wigglesworthia glossinidia, Wolbachia species, cyanobacterium Synechocystis 6803 and Mycoplasma pulmonis genomes all exhibit strand asymmetry patterns consistent with the multiple origins of replication, (2) different replication origins in some archaeal genomes leave quite different patterns of strand asymmetry, suggesting that different replication origins in the same genome may be differentially used, (3) mitochondrial genomes from representative vertebrate species share one strand asymmetry pattern consistent with the strand-displacement replication documented in mammalian mtDNA, suggesting that the mtDNA replication mechanism in mammals may be shared among all vertebrate species, and (4) mitochondrial genomes from primitive forms of metazoans such as the sponge and hydra (representing Porifera and Cnidaria, respectively), as well as those from plants, have strand asymmetry patterns similar to single-origin or multi-origin replications observed in prokaryotes and are drastically different from mitochondrial genomes from other metazoans. This may explain why sponge and hydra mitochondrial genomes, as well as plant mitochondrial genomes, evolves much slower than those from other metazoans.     

植酸酶高产菌株的诱变选育

无花果曲霉是一种可以产植酸酶的菌株,其代谢产物植酸酶可以将有机植酸磷降解为无机磷。以此菌株为出发菌株,确定了它的最适pH值为1.3~1.4,最适温度为55~60℃。同时,为获得高酶活的突变株,进行亚硝基胍和紫外线处理,经初筛得到99株高效突变株,再经复筛和传代试验,得到1株植酸酶活性是出发菌株2.47倍的突变株NTG-23。     

Comparison of redox and ligand binding behaviour of yeast and bovine cytochrome c oxidases using FTIR spectroscopy

Redox and CO photolysis FTIR spectra of yeast cytochrome c oxidase WT and mutants are compared to those from bovine and P. denitrificans CcOs in order to establish common functional features. All display changes that can be assigned to their E242 (bovine numbering) equivalent and to weakly H-bonded water molecules. The additional redox-sensitive band reported at 1736?cm^?1 in bovine CcO and previously assigned to D51 is absent from yeast CcO and couldn't be restored by introduction of a D residue at the equivalent position of the yeast protein. Redox spectra of yeast CcO also show much smaller changes in the amide I region, which may relate to structural differences in the region around D51 and the subunit I/II interface.     

Remarkable induction of UV-signature mutations at the 3′-cytosine of dipyrimidine sites except at 5′-TCG-3′ in the UVB-exposed skin epidermis of xeroderma pigmentosum variant model mice

The human POLH gene is responsible for the variant form of xeroderma pigmentosum (XP-V), a genetic disease highly susceptible to cancer on sun-exposed skin areas, and encodes DNA polymerase η (polη), which is specialized for translesion DNA synthesis (TLS) of UV-induced DNA photolesions. We constructed polη-deficient mice transgenic with lacZ mutational reporter genes to study the effect of Polh null mutation (Polh^−/−) on mutagenesis in the skin after UVB irradiation. UVB induced lacZ mutations with remarkably higher frequency in the Polh^−/− epidermis and dermis than in the wild-type (Polh^+/+) and heterozygote. DNA sequences of a hundred lacZ mutants isolated from the epidermis of four UVB-exposed Polh^−/− mice were determined and compared with mutant sequences from irradiated Polh^+/+ mice. The spectra of the mutations in the two genotypes were both highly UV-specific and dominated by C → T transitions at dipyrimidines, namely UV-signature mutations. However, sequence preferences of the occurrence of UV-signature mutations were quite different between the two genotypes: the mutations occurred at a higher frequency preferentially at the 5′-TCG-3′ sequence context than at the other dipyrimidine contexts in the Polh^+/+ epidermis, whereas the mutations were induced remarkably and exclusively at the 3′-cytosine of almost all dipyrimidine contexts with no preference for 5′-TCG-3′ in the Polh^−/− epidermis. In addition, in Polh^−/− mice, a small but remarkable fraction of G → T transversions was also observed exclusively at the 3′-cytosine of dipyrimidine sites, strongly suggesting that these transversions resulted not from oxidative damage but from UV photolesions. These results would reflect the characteristics of the error-prone TLS functioning in the bypass of UV photolesions in the absence of polη, which would be mediated by mechanisms based on the two-step model of TLS. On the other hand, the deamination model would explain well the mutation spectrum in the Polh^+/+ genotype.     

Mutability of microsatellites developed for the ant Camponotus consobrinus

Five highly polymorphic (GA)n microsatellite loci are reported for the formicine ant Camponotus consobrinus. The occurrence of many nests with a simple family structure enabled a search for new mutations, 11 of which were found from 3055 informative typings. These mutations were not randomly distributed across loci, 10 of them occurring at the locus Ccon70. The spectrum of mutations across alleles at Ccon70 was also nonrandom, with all of them occurring in alleles in the upper half of the allele size distribution. Six of the Ccon70 mutations decreased allele size. The mutations observed fit the stepwise mutation model well, i.e. mutations could always be assigned to an allele which differed in size from them by one repeat unit. The parental origins of the Ccon70 mutations were established and appear more female biased than vertebrate mutations, significantly so compared with human haemophilia A and primate intron mutations. This result may indicate that the lack of meiosis in males (which are haploid in ants) reduces the mutation rate in that sex relative to species in which both sexes are diploid.     

Arsenic trioxide promotes mitochondrial DNA mutation and cell apoptosis in primary APL cells and NB4 cell line

This study aimed to investigate the effects of arsenic trioxide (As₂O₃) on the mitochondrial DNA (mtDNA) of acute promyelocytic leukemia (APL) cells. The NB4 cell line was treated with 2.0 μmol/L As₂O₃ in vitro, and the primary APL cells were treated with 2.0 μmol/L As₂O₃ in vitro and 0.16 mg kg⁻¹ d⁻¹ As₂O₃ in vivo. The mitochondrial DNA of all the cells above was amplified by PCR, directly sequenced and analyzed by Sequence Navigatore and Factura software. The apoptosis rates were assayed by flow cytometry. Mitochondrial DNA mutation in the D-loop region was found in NB4 and APL cells before As₂O₃ use, but the mutation spots were remarkably increased after As₂O₃ treatment, which was positively correlated to the rates of cellular apoptosis, the correlation coefficient: r _NB4-As2O3=0.973818, and r _APL-As2O3=0.934703. The mutation types include transition, transversion, codon insertion or deletion, and the mutation spots in all samples were not constant and regular. It is revealed that As₂O₃ aggravates mtDNA mutation in the D-loop region of acute promyelocytic leukemia cells both in vitro and in vivo. Mitochondrial DNA might be one of the targets of As₂O₃ in APL treatment.