scholarly journals Toxicity of Commercial Neem Extract to Earthworms (Pheretima peguana)

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
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.

scholarly journals Is the Comet Assay a Sensitive Procedure for Detecting Genotoxicity?

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Satomi Kawaguchi ◽  
Takanori Nakamura ◽  
Ayumi Yamamoto ◽  
Gisho Honda ◽  
Yu F. Sasaki
Keyword(s):  
Comet Assay ◽  
Mammalian Cells ◽  
Positive Response ◽  
Micronucleus Test ◽  
Strand Breaks ◽  
Low Level ◽  
Genotoxic Potential ◽  
Dna Migration ◽  
Single Strand Breaks ◽  
Methyl Nitrosourea

Although the Comet assay, a procedure for quantitating DNA damage in mammalian cells, is considered sensitive, it has never been ascertained that its sensitivity is higher than the sensitivity of other genotoxicity assays in mammalian cells. To determine whether the power of the Comet assay to detect a low level of genotoxic potential is superior to those of other genotoxicity assays in mammalian cells, we compared the results of Comet assay with those of micronucleus test (MN test). WTK1 human lymphoblastoid cells were exposed to methyl nitrosourea (MNU), ethyl nitrosourea (ENU), methyl methanesulfonate (MMS), ethyl methanesulfonate (EMS), bleomycin (BLM), or UVC. In Comet assay, cells were exposed to each mutagen with (Comet assay/araC) and without (Comet assay) DNA repair inhibitors (araC and hydroxyurea). Furthermore, acellular Comet assay (acellular assay) was performed to determine how single-strand breaks (SSBs) as the initial damage contributes to DNA migration and/or to micronucleus formation. The lowest genotoxic dose (LGD), which is defined as the lowest dose at which each mutagen causes a positive response on each genotoxicity assay, was used to compare the power of the Comet assay to detect a low level of genotoxic potential and that of MN test; that is, a low LGD indicates a high power. Results are summarized as follows: (1) for all mutagens studied, LGDs were MN test ≦ Comet assay; (2) except for BLM, LGDs were Comet assay/araC ≦ MN test; (3) except for UVC and MNU, LGDs were acellular assay ≦ Comet assay/araC ≦ MN test ≦ Comet assay. The following is suggested by the present findings: (1) LGD in the Comet assay is higher than that in MN test, which suggests that the power of the MN test to detect a low level of genotoxic potential is superior to that of the Comet assay; (2) for the studied mutagens, all assays were able to detect all mutagens correctly, which suggests that the sensitivity of the Comet assay and that of the MN test were exactly identical; (3) the power of the Comet assay to detect a low level of genotoxic potential can be elevated to a level higher than that of MN test by using DNA resynthesis inhibitors, such as araC and HU.

scholarly journals Comparative Genotoxicity of Cadmium and Lead in Earthworm Coelomocytes

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Ptumporn Muangphra ◽  
Ravi Gooneratne
Keyword(s):  
Dna Damage ◽  
Comet Assay ◽  
Chromosomal Aberrations ◽  
Filter Paper ◽  
Micronucleus Test ◽  
Single Strand ◽  
Strand Breaks ◽  
Binucleate Cells ◽  
Single Strand Breaks ◽  
Cadmium And Lead

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.

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

2008 ◽  
Vol 30 (3) ◽  
pp. 77-85 ◽  
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

The enhancement of X-ray-induced DNA degradation in Micrococcus radiodurans by phenethyl alcohol

1971 ◽  
Vol 17 (4) ◽  
pp. 487-493 ◽  
Author(s):  
A. A. Driedger ◽  
M. J. Grayston
Keyword(s):  
Dna Synthesis ◽  
Excision Repair ◽  
Dna Degradation ◽  
Prolonged Incubation ◽  
Strand Breaks ◽  
X Ray ◽  
Phenethyl Alcohol ◽  
Single Strand Breaks ◽  
High Doses ◽  
Common Target

The effects of phenethyl alcohol on DNA synthesis and X-ray-induced DNA excision–repair were studied in Micrococcus radiodurans. At 0.20% concentration, the drug selectively inhibited DNA synthesis. Higher concentrations and prolonged incubation promoted DNA breakdown.Irradiation and PEA together promoted increased DNA breakdown in a characteristic fashion depending upon the time at which it was added. This effect was lost after the cells had undergone one postirradiation division. PEA did not inhibit repair of X-ray-induced single strand breaks. At high doses the two agents no longer enhanced each other's action and this suggests that they acted on a common target. It is proposed that X-ray-induced DNA breakdown is at least partly due to damage of a non-DNA structure such as the cell membrane, since persistent breaks in the DNA are not required for X-ray-induced, PEA-potentiated DNA degradation.

scholarly journals Sensitive CometChip assay for screening potentially carcinogenic DNA adducts by trapping DNA repair intermediates

2019 ◽  
Vol 48 (3) ◽  
pp. e13-e13 ◽  
Author(s):  
Le P Ngo ◽  
Norah A Owiti ◽  
Carol Swartz ◽  
John Winters ◽  
Yang Su ◽  
...  
Keyword(s):  
Comet Assay ◽  
Dna Adducts ◽  
Excision Repair ◽  
Environmental Chemicals ◽  
Single Strand ◽  
Strand Breaks ◽  
Single Strand Breaks ◽  
Bulky Dna Adducts ◽  
Dna Strand

Abstract Genotoxicity testing is critical for predicting adverse effects of pharmaceutical, industrial, and environmental chemicals. The alkaline comet assay is an established method for detecting DNA strand breaks, however, the assay does not detect potentially carcinogenic bulky adducts that can arise when metabolic enzymes convert pro-carcinogens into a highly DNA reactive products. To overcome this, we use DNA synthesis inhibitors (hydroxyurea and 1-β-d-arabinofuranosyl cytosine) to trap single strand breaks that are formed during nucleotide excision repair, which primarily removes bulky lesions. In this way, comet-undetectable bulky lesions are converted into comet-detectable single strand breaks. Moreover, we use HepaRG™ cells to recapitulate in vivo metabolic capacity, and leverage the CometChip platform (a higher throughput more sensitive comet assay) to create the ‘HepaCometChip’, enabling the detection of bulky genotoxic lesions that are missed by current genotoxicity screens. The HepaCometChip thus provides a broadly effective approach for detection of bulky DNA adducts.

The nature and origin of DNA single-strand breaks determined with the comet assay

1998 ◽  
Vol 409 (3) ◽  
pp. 163-171 ◽  
Author(s):  
Eva Horváthová ◽  
Darina Slameňová ◽  
Lucia Hlinčı́ková ◽  
Tapan Kumar Mandal ◽  
Alena Gábelová ◽  
...  
Keyword(s):  
Comet Assay ◽  
Single Strand ◽  
Strand Breaks ◽  
Single Strand Breaks

Mechanism of chromosome rearrangement arising from single-strand breaks

2021 ◽  
Author(s):  
Palina Kot ◽  
Takaaki Yasuhara ◽  
Atsushi Shibata ◽  
Miyako Hirakawa ◽  
Yu Abe ◽  
...  
Keyword(s):  
Chromosome Rearrangement ◽  
Single Strand ◽  
Strand Breaks ◽  
Single Strand Breaks
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