Comparative Genotoxicity of Cadmium and Lead in Earthworm Coelomocytes

To determine genotoxicity to coelomocytes,Pheretima peguanaearthworms were exposed in filter paper studies to cadmium (Cd) and lead (Pb) for 48 h, at concentrations less than the LC10—Cd: 0.09, 0.19, 0.38, 0.75, and 1.50 μg cm−2; Pb: 1.65, 3.29, 6.58, 13.16, and 26.32 μg cm−2. For Cd at 0.75 μg cm−2, in the micronucleus test (detects chromosomal aberrations), significant increases () in micronuclei and binucleate cells were observed, and in the comet assay (detects DNA single-strand breaks), tail DNA% was significantly increased. Lead was less toxic with minimal effects on DNA, but the binucleates were significantly increased by Pb at 3.29 μg cm−2. This study shows that Cd is more acutely toxic and sublethally genotoxic than Pb toP. peguana. Cadmium caused chromosomal aberrations and DNA single-strand breaks at 45% of the LC10concentration. Lead, in contrast, did not induce DNA damage but caused cytokinesis defects.

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The Role of DNA Damage and Repair in the Function of Eukaryotic Genes: Radiation-Induced Single-Strand Breaks and Their Rejoining in Chromosomal and Extrachromosomal Ribosomal DNA of Tetrahymena

Radiation Research ◽

10.2307/3575244 ◽

1980 ◽

Vol 82 (1) ◽

pp. 146 ◽

Cited By ~ 7

Author(s):

Song-Mao Chiu ◽

Nancy L. Oleinick

Keyword(s):

Dna Damage ◽

Ribosomal Dna ◽

Single Strand ◽

Dna Damage And Repair ◽

Strand Breaks ◽

Single Strand Breaks ◽

Eukaryotic Genes ◽

Radiation Induced

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Single-Strand Break End Resection in Genome Integrity: Mechanism and Regulation by APE2

International Journal of Molecular Sciences ◽

10.3390/ijms19082389 ◽

2018 ◽

Vol 19 (8) ◽

pp. 2389 ◽

Cited By ~ 16

Author(s):

Md. Hossain ◽

Yunfeng Lin ◽

Shan Yan

Keyword(s):

Dna Damage ◽

Genome Instability ◽

Strand Break ◽

Single Strand ◽

Genome Integrity ◽

Single Strand Break ◽

Strand Breaks ◽

Single Strand Breaks ◽

Damage Response ◽

End Resection

DNA single-strand breaks (SSBs) occur more than 10,000 times per mammalian cell each day, representing the most common type of DNA damage. Unrepaired SSBs compromise DNA replication and transcription programs, leading to genome instability. Unrepaired SSBs are associated with diseases such as cancer and neurodegenerative disorders. Although canonical SSB repair pathway is activated to repair most SSBs, it remains unclear whether and how unrepaired SSBs are sensed and signaled. In this review, we propose a new concept of SSB end resection for genome integrity. We propose a four-step mechanism of SSB end resection: SSB end sensing and processing, as well as initiation, continuation, and termination of SSB end resection. We also compare different mechanisms of SSB end resection and DSB end resection in DNA repair and DNA damage response (DDR) pathways. We further discuss how SSB end resection contributes to SSB signaling and repair. We focus on the mechanism and regulation by APE2 in SSB end resection in genome integrity. Finally, we identify areas of future study that may help us gain further mechanistic insight into the process of SSB end resection. Overall, this review provides the first comprehensive perspective on SSB end resection in genome integrity.

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Potential Path of DNA Damage: Electron Attachment–Induced DNA Single-Strand Breaks

Practical Aspects of Computational Chemistry II ◽

10.1007/978-94-007-0923-2_14 ◽

2012 ◽

pp. 511-536

Author(s):

Jiande Gu ◽

Jing Wang ◽

Jerzy Leszczynski

Keyword(s):

Dna Damage ◽

Electron Attachment ◽

Single Strand ◽

Strand Breaks ◽

Single Strand Breaks

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DNA damage response by single-strand breaks in terminally differentiated muscle cells and the control of muscle integrity

Cell Death and Differentiation ◽

10.1038/cdd.2012.53 ◽

2012 ◽

Vol 19 (11) ◽

pp. 1741-1749 ◽

Cited By ~ 32

Author(s):

P Fortini ◽

C Ferretti ◽

B Pascucci ◽

L Narciso ◽

D Pajalunga ◽

...

Keyword(s):

Dna Damage ◽

Dna Damage Response ◽

Muscle Cells ◽

Single Strand ◽

Strand Breaks ◽

Single Strand Breaks ◽

Damage Response

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Toxicity of Commercial Neem Extract to Earthworms (Pheretima peguana)

Applied and Environmental Soil Science ◽

10.1155/2011/925950 ◽

2011 ◽

Vol 2011 ◽

pp. 1-8 ◽

Cited By ~ 7

Author(s):

Ptumporn Muangphra ◽

Ravi Gooneratne

Keyword(s):

Comet Assay ◽

Body Wall ◽

Micronucleus Test ◽

Agricultural Practices ◽

Recommended Dosage ◽

Neem Extract ◽

Strand Breaks ◽

Single Strand Breaks ◽

Radial Thickness ◽

High Doses

The LC50of commercial neem extract (Sadao Thai III containing azadirachtin; NEEM) on filter paper in the earthwormPheretima peguanaat 48 h and 72 h was 3.79 and 3.33 g , respectively. In earthworms exposed to five NEEM concentrations from 0.39 (~10% of 48-h LC50) to 3.13 (~80% of 48-h LC50) g , the radial thickness of the epidermis and body wall significantly () decreased, and thickness of intestinal epithelium increased but only at high doses, approximately 25-fold above the concentration permitted for use as an insecticide in field applications (0.09 g ). NEEM significantly () increased the number of binucleated coelomocytes in the micronucleus test (detects chromosomal aberrations) at 3.13 g , approximately 35-fold higher than the recommended dose, but it did not cause coelomocyte DNA single-strand breaks in the comet assay. Thus, NEEM is cytotoxic (increase in binucleates through the inhibition of cytokinesis) but not genotoxic to earthworm coelomocytes. This study demonstrates that the recommended dosage of commercial neem extract as an insecticide in agricultural practices is safe for earthworms.

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Detection of DNA Single Strand Breaks Induced by Chemical Mutagens Using the Acellular Comet Assay

Genes and Environment ◽

10.3123/jemsge.30.77 ◽

2008 ◽

Vol 30 (3) ◽

pp. 77-85 ◽

Cited By ~ 6

Author(s):

Satomi Kawaguchi ◽

Takanori Nakamura ◽

Gisho Honda ◽

Natsue Yokohama ◽

Yu F. Sasaki

Keyword(s):

Comet Assay ◽

Single Strand ◽

Strand Breaks ◽

Chemical Mutagens ◽

Single Strand Breaks

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A CAF-1–PCNA-Mediated Chromatin Assembly Pathway Triggered by Sensing DNA Damage

Molecular and Cellular Biology ◽

10.1128/mcb.20.4.1206-1218.2000 ◽

2000 ◽

Vol 20 (4) ◽

pp. 1206-1218 ◽

Cited By ~ 204

Author(s):

Jonathan G. Moggs ◽

Paola Grandi ◽

Jean-Pierre Quivy ◽

Zophonías O. Jónsson ◽

Ulrich Hübscher ◽

...

Keyword(s):

Dna Damage ◽

Dna Repair ◽

Single Strand ◽

Chromatin Assembly ◽

Checkpoint Control ◽

Free System ◽

Strand Breaks ◽

Assembly Pathway ◽

Single Strand Breaks ◽

Damaged Dna

ABSTRACT Sensing DNA damage is crucial for the maintenance of genomic integrity and cell cycle progression. The participation of chromatin in these events is becoming of increasing interest. We show that the presence of single-strand breaks and gaps, formed either directly or during DNA damage processing, can trigger the propagation of nucleosomal arrays. This nucleosome assembly pathway involves the histone chaperone chromatin assembly factor 1 (CAF-1). The largest subunit (p150) of this factor interacts directly with proliferating cell nuclear antigen (PCNA), and critical regions for this interaction on both proteins have been mapped. To isolate proteins specifically recruited during DNA repair, damaged DNA linked to magnetic beads was used. The binding of both PCNA and CAF-1 to this damaged DNA was dependent on the number of DNA lesions and required ATP. Chromatin assembly linked to the repair of single-strand breaks was disrupted by depletion of PCNA from a cell-free system. This defect was rescued by complementation with recombinant PCNA, arguing for role of PCNA in mediating chromatin assembly linked to DNA repair. We discuss the importance of the PCNA–CAF-1 interaction in the context of DNA damage processing and checkpoint control.

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