scholarly journals Response of the Hyperthermophilic Archaeon Sulfolobus solfataricus to UV Damage

2007 ◽  
Vol 189 (23) ◽  
pp. 8708-8718 ◽  
Author(s):  
Sabrina Fröls ◽  
Paul M. K. Gordon ◽  
Mayi Arcellana Panlilio ◽  
Iain G. Duggin ◽  
Stephen D. Bell ◽  
...  
Keyword(s):  
Dna Microarrays ◽  
Sulfolobus Solfataricus ◽  
Genetic Material ◽  
Transcriptional Response ◽  
Microscopic Analysis ◽  
Large Cell ◽  
Recombinational Repair ◽  
Supporting Evidence ◽  
Uv Damage ◽  
Dna Double Strand Breaks

ABSTRACT In order to characterize the genome-wide transcriptional response of the hyperthermophilic, aerobic crenarchaeote Sulfolobus solfataricus to UV damage, we used high-density DNA microarrays which covered 3,368 genetic features encoded on the host genome, as well as the genes of several extrachromosomal genetic elements. While no significant up-regulation of genes potentially involved in direct DNA damage reversal was observed, a specific transcriptional UV response involving 55 genes could be dissected. Although flow cytometry showed only modest perturbation of the cell cycle, strong modulation of the transcript levels of the Cdc6 replication initiator genes was observed. Up-regulation of an operon encoding Mre11 and Rad50 homologs pointed to induction of recombinational repair. Consistent with this, DNA double-strand breaks were observed between 2 and 8 h after UV treatment, possibly resulting from replication fork collapse at damaged DNA sites. The strong transcriptional induction of genes which potentially encode functions for pilus formation suggested that conjugational activity might lead to enhanced exchange of genetic material. In support of this, a statistical microscopic analysis demonstrated that large cell aggregates formed upon UV exposure. Together, this provided supporting evidence to a link between recombinational repair and conjugation events.

Laser scanning confocal microscopic analysis of cytoskeletal and nuclear reorganization in live Drosophila embryos

1993 ◽  
Vol 51 ◽  
pp. 174-175
Author(s):  
William Theurkauf
Keyword(s):  
Laser Scanning ◽  
Microscopic Analysis ◽  
Large Cell ◽  
Early Embryo ◽  
Drosophila Embryo ◽  
Cortical Actin ◽  
Nuclear Reorganization ◽  
Cytoskeletal Elements ◽  
Microtubule Structure ◽  
Drosophila Embryos

Cell division in eucaryotes depends on coordinated changes in nuclear and cytoskeletal components. In Drosophila melanogaster embryos, the first 13 nuclear divisions occur without cytokinesis. During the final four divisions, nuclei divide in a uniform monolayer at the surface of the embryo. These surface divisions are accompanied by dramatic changes in cortical actin and microtubule structure (Karr and Alberts, 1986), and inhibitor studies indicate that these changes are essential to orderly mitosis (Zalokar and Erk, 1976). Because the early embryo is syncytial, fluorescent probes introduced by microinjection are incorporated in structures associated with all of the nuclei in the blastoderm. In addition, the nuclei divide synchronously every 10 to 20 min. These characteristics make the syncytial blastoderm embryo an excellent system for the analysis of mitotic reorganization of both nuclear and cytoskeletal elements. However, the Drosophila embryo is a large cell, and resolution of cytoskeletal filaments and nuclear structure is hampered by out-of focus signal.

scholarly journals A novel DNA helicase with strand-annealing activity from the crenarchaeon Sulfolobus solfataricus

2007 ◽  
Vol 408 (1) ◽  
pp. 87-95 ◽  
Author(s):  
Mariarita De Felice ◽  
Valentina Aria ◽  
Luca Esposito ◽  
Mariarosaria De Falco ◽  
Biagio Pucci ◽  
...  
Keyword(s):  
High Efficiency ◽  
Biochemical Characterization ◽  
Sequence Similarity ◽  
Sulfolobus Solfataricus ◽  
Genetic Material ◽  
Dna Helicase ◽  
Soluble Form ◽  
Monomeric Form ◽  
Genome Database ◽  
Strand Annealing

To protect their genetic material cells adopt different mechanisms linked to DNA replication, recombination and repair. Several proteins function at the interface of these DNA transactions. In the present study, we report on the identification of a novel archaeal DNA helicase. BlastP searches of the Sulfolobus solfataricus genome database allowed us to identify an open reading frame (SSO0112, 875 amino acid residues) having sequence similarity with the human RecQ5β. The corresponding protein, termed Hel112 by us, was produced in Escherichia coli in soluble form, purified to homogeneity and characterized. Gel-filtration chromatography and glycerol-gradient sedimentation analyses revealed that Hel112 forms monomers and dimers in solution. Biochemical characterization of the two oligomeric species revealed that only the monomeric form has an ATP-dependent 3′–5′ DNA-helicase activity, whereas, unexpectedly, both the monomeric and dimeric forms possess DNA strand-annealing capability. The Hel112 monomeric form is able to unwind forked and 3′-tailed DNA structures with high efficiency, whereas it is almost inactive on blunt-ended duplexes and bubble-containing molecules. This analysis reveals that S. solfataricus Hel112 shares some enzymatic features with the RecQ-like DNA helicases and suggests potential cellular functions of this protein.

scholarly journals The cohesin-like RecN protein stimulates RecA-mediated recombinational repair of DNA double-strand breaks

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Lee A. Uranga ◽  
Emigdio D. Reyes ◽  
Praveen L. Patidar ◽  
Lindsay N. Redman ◽  
Shelley L. Lusetti
Keyword(s):  
Double Strand Breaks ◽  
Recombinational Repair ◽  
Dna Double Strand Breaks ◽  
Strand Breaks

scholarly journals Critical Role of RecN in Recombinational DNA Repair and Survival of Helicobacter pylori

2007 ◽  
Vol 76 (1) ◽  
pp. 153-160 ◽  
Author(s):  
Ge Wang ◽  
Robert J. Maier
Keyword(s):  
Helicobacter Pylori ◽  
Parent Strain ◽  
Dna Recombination ◽  
Double Strand Breaks ◽  
Recombinational Repair ◽  
Wild Type ◽  
Dna Double Strand Breaks ◽  
Air Exposure ◽  
Strand Breaks ◽  
H Pylori

ABSTRACT Homologous recombination is one of the key mechanisms responsible for the repair of DNA double-strand breaks. Recombinational repair normally requires a battery of proteins, each with specific DNA recognition, strand transfer, resolution, or other functions. Helicobacter pylori lacks many of the proteins normally involved in the early stage (presynapsis) of recombinational repair, but it has a RecN homologue with an unclear function. A recN mutant strain of H. pylori was shown to be much more sensitive than its parent to mitomycin C, an agent predominantly causing DNA double-strand breaks. The recN strain was unable to survive exposure to either air or acid as well as the parent strain, and air exposure resulted in no viable recN cells recovered after 8 h. In oxidative stress conditions (i.e., air exposure), a recN strain accumulated significantly more damaged (multiply fragmented) DNA than the parent strain. To assess the DNA recombination abilities of strains, their transformation abilities were compared by separately monitoring transformation using H. pylori DNA fragments containing either a site-specific mutation (conferring rifampin resistance) or a large insertion (kanamycin resistance cassette). The transformation frequencies using the two types of DNA donor were 10- and 50-fold lower, respectively, for the recN strain than for the wild type, indicating that RecN plays an important role in facilitating DNA recombination. In two separate mouse colonization experiments, the recN strain colonized most of the stomachs, but the average number of recovered cells was 10-fold less for the mutant than for the parent strain (a statistically significant difference). Complementation of the recN strain by chromosomal insertion of a functional recN gene restored both the recombination frequency and mouse colonization ability to the wild-type levels. Thus, H. pylori RecN, as a component of DNA recombinational repair, plays a significant role in H. pylori survival in vivo.

scholarly journals DNA Damaged Induced Cell Death in Oocytes

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5714
Author(s):  
Jakob Gebel ◽  
Marcel Tuppi ◽  
Nicole Sänger ◽  
Björn Schumacher ◽  
Volker Dötsch
Keyword(s):  
Quality Control ◽  
Control System ◽  
Molecular Mechanisms ◽  
P53 Protein ◽  
Genetic Material ◽  
Fruit Fly ◽  
Quality Control System ◽  
Premature Menopause ◽  
Dna Double Strand Breaks ◽  
Homologous Chromosomes

The production of haploid gametes through meiosis is central to the principle of sexual reproduction. The genetic diversity is further enhanced by exchange of genetic material between homologous chromosomes by the crossover mechanism. This mechanism not only requires correct pairing of homologous chromosomes but also efficient repair of the induced DNA double-strand breaks. Oocytes have evolved a unique quality control system that eliminates cells if chromosomes do not correctly align or if DNA repair is not possible. Central to this monitoring system that is conserved from nematodes and fruit fly to humans is the p53 protein family, and in vertebrates in particular p63. In mammals, oocytes are stored for a long time in the prophase of meiosis I which, in humans, can last more than 50 years. During the entire time of this arrest phase, the DNA damage checkpoint remains active. The treatment of female cancer patients with DNA damaging irradiation or chemotherapeutics activates this checkpoint and results in elimination of the oocyte pool causing premature menopause and infertility. Here, we review the molecular mechanisms of this quality control system and discuss potential therapeutic intervention for the preservation of the oocyte pool during chemotherapy.

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