Use of the random amplified polymorphic DNA (RAPD) assay for the detection of DNA damage and mutations: possible implications of confounding factors

Exogenous melatonin enhances the tolerance of tiger nut (Cyperus esculentus L.) via DNA damage repair pathway under heavy metal stress (Cd2+) at the sprout stage

Heavy metal (HM) stress is a non-negligible abiotic stress that seriously restricts crop yield and quality, while the sprout stage is the most sensitive to stress and directly impacts the growth and development of the later stage. Melatonin (N-acetyl-5-methoxytryptamine), as an exogenous additive, enhances stress resistance due to its ability to oxidize and reduce. However, few reports on exogenous melatonin to tiger nuts under HM stress have explored whether exogenous melatonin enhances plants' resistance to heavy metals. Here, "Jisha 2″ was used as material, with a stress concentration of 5 mg/L and 100 μmol/L of CdCl2 to explore whether exogenous melatonin enhances plant resistance and molecular mechanism. The result revealed that stress limits growth, while melatonin alleviated the sprout damage under stress from the phenotypes. Moreover, stress-enhanced reactive oxygen species (ROS) accumulation and membrane lipid peroxidation, while melatonin-increased ROS reduce damage via the analysis of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) and malondialdehyde (MDA) content, hydrogen peroxide (H2O2), superoxide anion (O2-), and Electrolyte leakage (El). Further results indicated that HM leads to DNA damage while exogenous melatonin will repair the damage by analyzing random amplified polymorphic DNA (RAPD), DNA cross-linking, 8-hydroxy-20-deoxyguanine level, and relative density of apurinic sites. Furthermore, gene expression in the DNA-repaired pathway exhibited similar results. These results applied that exogenous melatonin released the hurt caused by HM stress, with DNA repair and ROS balance serving as candidate pathways. This study elucidated the mechanism of melatonin's influence and provided theoretical insights into its application in tiger nuts.

Synergistic Antimicrobial Effect of Cold Atmospheric Plasma and Redox-Active Nanoparticles

Cold argon plasma (CAP) and metal oxide nanoparticles are well known antimicrobial agents. In the current study, on an example of Escherichia coli, a series of analyses was performed to assess the antibacterial action of the combination of these agents and to evaluate the possibility of using cerium oxide and cerium fluoride nanoparticles for a combined treatment of bacterial diseases. The joint effect of the combination of cold argon plasma and several metal oxide and fluoride nanoparticles (CeO2, CeF3, WO3) was investigated on a model of E. coli colony growth on agar plates. The mutagenic effect of different CAP and nanoparticle combinations on bacterial DNA was investigated, by means of a blue-white colony assay and RAPD-PCR. The effect on cell wall damage, using atomic force microscopy, was also studied. The results obtained demonstrate that the combination of CAP and redox-active metal oxide nanoparticles (RAMON) effectively inhibits bacterial growth, providing a synergistic antimicrobial effect exceeding that of any of the agents alone. The combination of CAP and CeF3 was shown to be the most effective mutagen against plasmid DNA, and the combination of CAP and WO3 was the most effective against bacterial genomic DNA. The analysis of direct cell wall damage by atomic force microscopy showed the combination of CAP and CeF3 to be the most effective antimicrobial agent. The combination of CAP and redox-active metal oxide or metal fluoride nanoparticles has a strong synergistic antimicrobial effect on bacterial growth, resulting in plasmid and genomic DNA damage and cell wall damage. For the first time, a strong antimicrobial and DNA-damaging effect of CeF3 nanoparticles has been demonstrated.

Antibacterial, Antioxidant Activities, GC-Mass Characterization, and Cyto/Genotoxicity Effect of Green Synthesis of Silver Nanoparticles Using Latex of Cynanchum acutum L

Green synthesis of nanoparticles is receiving more attention these days since it is simple to use and prepare, uses fewer harsh chemicals and chemical reactions, and is environmentally benign. A novel strategy aims to recycle poisonous plant chemicals and use them as natural stabilizing capping agents for nanoparticles. In this investigation, silver nanoparticles loaded with latex from Cynanchum acutum L. (Cy-AgNPs) were examined using a transmission electron microscope, FT-IR spectroscopy, and UV-visible spectroscopy. Additionally, using Vicia faba as a model test plant, the genotoxicity and cytotoxicity effects of crude latex and various concentrations of Cy-AgNPs were studied. The majority of the particles were spherical in shape. The highest antioxidant activity using DPPH was illustrated for CAgNPs (25 mg/L) (70.26 ± 1.32%) and decreased with increased concentrations of Cy-AGNPs. Antibacterial activity for all treatments was determined showing that the highest antibacterial activity was for Cy-AgNPs (50 mg/L) with inhibition zone 24 ± 0.014 mm against Bacillus subtilis, 19 ± 0.12 mm against Escherichia coli, and 23 ± 0.015 against Staphylococcus aureus. For phytochemical analysis, the highest levels of secondary metabolites from phenolic content, flavonoids, tannins, and alkaloids, were found in Cy-AgNPs (25 mg/L). Vicia faba treated with Cy-AgNPs- (25 mg/L) displayed the highest mitotic index (MI%) value of 9.08% compared to other Cy-AgNP concentrations (50-100 mg/L) and C. acutum crude latex concentrations (3%). To detect cytotoxicity, a variety of chromosomal abnormalities were used, including micronuclei at interphase, disturbed at metaphase and anaphase, chromosomal stickiness, bridges, and laggards. The concentration of Cy-AgNPs (25 mg/L) had the lowest level of chromosomal aberrations, with a value of 23.41% versus 20.81% for the control. Proteins from seeds treated with V. faba produced sixteen bands on SDS-PAGE, comprising ten monomorphic bands and six polymorphic bands, for a total percentage of polymorphism of 37.5%. Eight ISSR primers were employed to generate a total of 79 bands, 56 of which were polymorphic and 23 of which were common. Primer ISSR 14 has the highest level of polymorphism (92.86%), according to the data. Using biochemical SDS-PAGE and ISSR molecular markers, Cy-AgNPs (25 mg/L) showed the highest percentage of genomic template stability (GTS%), with values of 80% and 51.28%, respectively. The findings of this work suggest employing CyAgNPs (25 mg/L) in pharmaceutical purposes due to its highest content of bioactive compounds and lowest concentration of chromosomal abnormalities.

Effects of magnetite nanoparticles on physiological processes to alleviate salinity induced oxidative damage in wheat

BACKGROUND

One of the major abiotic stressors that have a serious effect on plant growth and productivity worldwide is the salinity of soil or irrigation water. The effect of foliar application of magnetite nanoparticles (size = 22.05 nm) at different concentrations (0, 0.25, 0.5, and 1.0 ppm) was investigated to improve salinity tolerance in two wheat cultivars, namely, Misr1 (Tolerant) and Gimmeza11 (Sensitive). Moreover, toxicological investigations of magnetite oxide nanoparticle in Wistar albino rats were estimated.

RESULTS

The magnetite nanoparticles positively affected growth, chlorophyll, and enzymatic antioxidants such as superoxide dismutase (SOD), stimulating reduced glutathione and improving the aggregation of several polypeptide chains that may be linked to the tolerance of saline stress. In contrast, magnetite nanoparticles reduced malondialdehyde (MDA). Inverse sequence-tagged repeat (ISTR) assay of DNA molecular marker showed the change in band numbers with the highest polymorphic bands with 90% polymorphism at primer F3, B5 and 20 positive bands in Gimmeza11 with 0.5 ppm magnetite nanoparticles. In the median lethal dose (LD₅₀ ) study, no rats died after the oral administration of magnetite nanoparticle at different doses. Therefore, the iron oxide nanoparticle was nontoxic when administered orally by gavage.

CONCLUSION

Magnetite nanoparticles partially helped to alleviate the effects of salt stress by activating growth, chlorophyll content, SOD, glutathione, and soluble proteins in two wheat cultivars (Misr1 and Gimmeza11) and decreasing MDA content. © 2021 Society of Chemical Industry.

Tolerances of Deinococcus geothermalis Biofilms and Planktonic Cells Exposed to Space and Simulated Martian Conditions in Low Earth Orbit for Almost Two Years

Fossilized biofilms represent one of the oldest known confirmations of life on the Earth. The success of microbes in biofilms results from properties that are inherent in the biofilm, including enhanced interaction, protection, and biodiversity. Given the diversity of microbes that live in biofilms in harsh environments on the Earth, it is logical to hypothesize that, if microbes inhabit other bodies in the Universe, there are also biofilms on those bodies. The Biofilm Organisms Surfing Space experiment was conducted as part of the EXPOSE-R2 mission on the International Space Station. The experiment was an international collaboration designed to perform a comparative study regarding the survival of biofilms versus planktonic cells of various microorganisms, exposed to space and Mars-like conditions. The objective was to determine whether there are lifestyle-dependent differences to cope with the unique mixture of stress factors, including desiccation, temperature oscillations, vacuum, or a Mars-like gas atmosphere and pressure in combination with extraterrestrial or Mars-like ultraviolet (UV) radiation residing during the long-term space mission. In this study, the outcome of the flight and mission ground reference analysis of Deinococcus geothermalis is presented. Cultural tests demonstrated that D. geothermalis remained viable in the desiccated state, being able to survive space and Mars-like conditions and tolerating high extraterrestrial UV radiation for more than 2 years. Culturability decreased, but was better preserved, in the biofilm consortium than in planktonic cells. These results are correlated to differences in genomic integrity after exposure, as visualized by random amplified polymorphic DNA-polymerase chain reaction. Interestingly, cultivation-independent viability markers such as membrane integrity, ATP content, and intracellular esterase activity remained nearly unaffected, indicating that subpopulations of the cells had survived in a viable but nonculturable state. These findings support the hypothesis of long-term survival of microorganisms under the harsh environmental conditions in space and on Mars to a higher degree if exposed as biofilm.

Genotoxic evaluation of newly synthesized iminothiazolidinones

The current study was designed to assess the potential toxicological effects of newly synthesized iminothiazolidinones by employing Ames Salmonella, Escherichia coli WP2, Zea mays seed germination, and random amplified polymorphic DNA (RAPD) assay systems. The bacterial tester strains S. typhimurium TA1535, TA1537, TA1538, TA98, TA100, and E. coli WP2 uvrA were chosen to test the direct gene mutation inducing capabilities of the test materials in prokaryotic systems and Z. mays seeds for determination of potential toxicological effects in eukaryotic systems. OPA-3 and OPA-6 primers were used in the RAPD analysis to determine genotoxic activities on the eukaryotic genomes. According to the results, none of the test materials showed significant mutagenic activity on the bacterial tester strains at the chosen concentrations. Additionally, none of the tested compounds showed inhibition of the germination of Z. mays seeds. In contrast, the RAPD analysis results were inconsistent with the bacterial reversion assays and the seed germination assay results. All test materials significantly changed the RAPD profiles for OPA-3; however, only compound 5 showed a significant change for OPA-6 when compared with the control groups. In conclusion, the newly synthesized iminothiazolidinone derivatives (C1-C5) were determined as potentially genotoxic compounds and they should be checked with multiple toxicology test systems before further studies to determine their actual use.

Evaluation of the antimicrobial activities of ultrasonicated spinach leaf extracts using RAPD markers and electron microscopy

Spinach (Spinacia oleracea L.) leaves represent an important dietary source of nutrients, antioxidants and antimicrobials. As such, spinach leaves play an important role in health and have been used in the treatment of human diseases since ancient times. Here, the aims were to optimize the extraction methods for recovering antimicrobial substances of spinach leaves, determine the minimum inhibitory concentrations (MICs) of the antimicrobial substances against Escherichia coli and Staphylococcus aureus and, finally, evaluate the effects of spinach leaves' antimicrobials on bacterial DNA using central composite face-centered methods. The effect of the extracts on both Gram-positive and Gram-negative bacterial models was examined by scanning electron microscopy (SEM) and random amplification of polymorphic (bacterial) DNA (RAPD). The optimal extraction conditions were at 45 °C, ultrasound power of 44% and an extraction time of 23 min. The spinach extracts exhibited antimicrobial activities against both bacteria with MICs in the 60-100 mg/ml range. Interestingly, SEM showed that the treated bacterial cells appear damaged with a reduction in cell number. RAPD analysis of genomic DNA showed that the number and sizes of amplicons were decreased by treatments. Based on these results, it was inferred that spinach leaf extracts exert bactericidal activities by both inducing mutations in DNA and causing cell wall disruptions.

RAPD-PCR as a Rapid Approach for the Evaluation of Genotoxin-Induced Damage to Bacterial DNA

RAPD PCR is a sensitive and reliable approach useful for the detection of DNA lesions due to environmental contaminants. In addition, this method is cost-effective, and can be performed in any laboratory having a DNA thermocycler and gel electrophoresis system. Here, we describe its application to identify genotoxin-induced DNA damage in foodborne bacteria. DNA alterations are detected through the analysis of electrophoresis profiles with the appearance or disappearance of new bands as compared to the non-mutated control. The described RAPD PCR procedure takes 6 h for completion. It uses small amounts of DNA and can reveal even low mutation rates.

Food borne bacterial models for detection of benzo[a]pyrene-DNA adducts formation using RAPD-PCR

Random amplified polymorphic DNA (RAPD) PCR is a feasible method to evaluate genotoxin-induced DNA damage and mutations. In this study, Lactobacillus plantarum ATCC 14917T, Enterococcus faecium DSMZ 20477T, Escherichia coli PQ37 and Saccharomyces cerevisiae S441 were screened for DNA genetic alterations by DNA fingerprinting using M13 and LA1 primers after treatment with three compounds forming covalent adducts with DNA [benzo[a]pyrenediol epoxide (BPDE), methyl methanesulfonate and 1,2,3,4-diepoxybutane (DEB)]. M13 RAPD fingerprinting revealed that the total number of bands decreased in all treated DNA compared to control samples and generally the lost bands were characterized by high molecular weight. Some extra bands were detected for L. plantarum and E. faecium, while in E. coli and S. cerevisiae DNAs BPDE and DEB treatments did not result in new extra bands. Besides qualitatively analysis, cluster analysis based on Unweighted Pair-Group Method with Average algorithm was performed to compare DNA fingerprints before and after treatments. This analysis confirmed the absence of significant differences between negative controls and treated DNA in S. cerevisiae and E. coli however the disappearance of some bands can be detected. The data indicate that this approach can be used for DNA damage detection and mutations induced by genotoxic compounds and highlighted the possible use of L. plantarum and E. faecium M13 based fingerprinting as reference for hazard identification in risk assessment.

Radiation-induced phenotypic alterations in relation to isozymes and RAPD markers inVigna radiata(L.) Wilczek

PURPOSE

The present investigation is aimed at studies on the effects of gamma rays on in vitro and in vivo damage in Vigna radiata. The parameters studied are germination frequency, seedling injury, isozyme alteration and random amplified polymorphic DNA (RAPD) markers. Results obtained are analyzed in the light of modern applications of radiation damage.

MATERIALS AND METHODS

Seeds of Vigna radiata were subjected to gamma irradiation with a dose of 20 - 200 Gy. The percent of seedling damage and frequency of germination were determined. Callus samples were produced in vitro and exposed to gamma rays. The irradiated callus samples were processed to extract total protein, and specifically stained for superoxide dismutase (SOD) and peroxidase isozymes. Total genomic DNA was extracted from irradiated callus samples and subjected to random amplified polymorphic DNA analysis using 23 random decamer primers.

RESULTS

Gamma irradiation resulted in retardation in seedling height and decrease in germination frequency in a dose dependent manner. Inhibition assay identified variation in response between different isoforms of SOD on radiation exposure. Changes in peroxidase activity were also observed following irradiation. RAPD analysis showed that new bands appeared in the 20 Gy irradiated sample which in the case of some primers showed similarity with the control. The calli irradiated with 50 Gy and 100 Gy of gamma rays was found to have striking resemblance in banding pattern. Callus irradiated at 200 Gy showed maximum damage. DNA damage as revealed by RAPD analysis was reflected in the appearance of new bands with varying molecular weights.

CONCLUSION

New isoforms of SOD appeared after irradiation followed by 24 h recovery. Some isoforms of peroxidase reappeared in calli after 24 h recovery. Results of RAPD analysis indicated that the DNA polymorphism was dose dependent.

PCR based detection of furadan genotoxicity effects in rohu (Labeo rohita) fingerlings

The present study involves the use of RAPD-PCR to evaluate the genotoxic effects of furadan in the DNA of Labeo rohita (rohu) fingerlings. Rohu fingerlings were exposed to 0.02 ppm of furadan for a total period of 96 h and samplings were done at 24, 48, 72 and 96 h. RAPD - PCR were carried out with the blood and liver DNA samples of both control and treated groups at each of the four sampling hours. A total of six selected RAPD primers were used for PCR amplification. Template stability has been taken as the measure of DNA damage caused by pesticide. The results obtained showed no significant difference in the template stability in the blood DNA of furadan treated groups at any of the four sampling hours; however, the liver DNA were able to show significant difference at 48 and 96 hours of treatment.

Radiation induced alterations in Vigna radiata during in vitro somatic embryogenesis

PURPOSE

Tissue culture has been exploited to understand molecular aspects of regeneration potential of the plants in normal and in stressed conditions. The present study describes ionizing radiation from (60)Co source as the stress stimulator to assess in vitro development of somatic embryo of Vigna radiata, a protein-rich pulse.

MATERIALS AND METHODS

Callus culture was established, using leaves of V. radiata. Somatic embryogenesis was induced by manipulating plant hormones. Calli were exposed to gamma rays. Genomic DNA isolated from gamma-irradiated callus samples were subjected to random amplified polymorphic DNA analysis. A band of molecular weight 1440 bp was used as a probe and Southern hybridization was carried out. To determine alterations in DNA following irradiation, RAPD bands were cloned and sequenced from control and irradiated samples. Embryogenic calli were exposed to gamma irradiation and the effects were assessed immediately and after seven days of exposure. Phenotypic alterations were observed using scanning electron microscopy.

RESULTS

Exposed calli revealed altered frequency of somatic embryo formation. Results showed that the 1440 bp molecular weight probe hybridized with bands of low molecular weight. DNA sequences from irradiated samples showed recombination when compared to control. Scanning electron micrography illustrated presence of transient pores on the exposed embryos. BLAST search of the DNA sequences showed partial homology with some sequences from Arabidopsis thaliana.

CONCLUSION

The present report might help in designing a breeding program, where both radiation coupled with somatic embryogenesis could be employed to build up the desired variants.

The random amplified polymorphic DNA (RAPD) assay and related techniques applied to genotoxicity and carcinogenesis studies: a critical review

More than 9000 papers using the random amplified polymorphic DNA (RAPD) or related techniques (e.g. the arbitrarily primed polymerase chain reaction (AP-PCR)) have been published from 1990 to 2005. The RAPD method has been initially used to detect polymorphism in genetic mapping, taxonomy and phylogenetic studies and later in genotoxicity and carcinogenesis studies. Despite their extensive use, these techniques have also attracted some criticisms, mainly for lack of reproducibility. In the light of their widespread applications, the objectives of this review are to (1) identify the potential factors affecting the optimisation of the RAPD and AP-PCR assays, (2) critically describe and analyse these techniques in genotoxicity and carcinogenesis studies, (3) compare the RAPD assay with other well used methodologies, (4) further elucidate the impact of DNA damage and mutations on the RAPD profiles, and finally (5) provide some recommendations/guidelines to further improve the applications of the assays and to help the identification of the factors responsible for the RAPD changes. It is suggested that after proper optimisation, the RAPD is a reliable, sensitive and reproducible assay, has the potential to detect a wide range of DNA damage (e.g. DNA adducts, DNA breakage) as well as mutations (point mutations and large rearrangements) and therefore can be applied to genotoxicity and carcinogenesis studies. Nevertheless, the interpretation of the changes in RAPD profiles is difficult since many factors can affect the generation of RAPD profiles. It is therefore important that these factors are identified and taken into account while using these assays. On the other hand, further analyses of the relevant bands generated in RAPD profile allow not only to identify some of the molecular events implicated in the genomic instability but also to discover genes playing key roles, particularly in the initiation and development of malignancy. Finally, to elucidate the potential genotoxic effects of environmental contaminants, a powerful strategy could be firstly to use the RAPD assay as a screening method and secondly to apply more specific methods measuring for instance DNA adducts, gene mutations or cytogenetic effects. It is also envisaged that these assays (i.e. RAPD and related techniques), which reflect effects at whole genome level, would continue to complement the use of emerging technologies (e.g. microarrays which aim to quantify expression of individual genes).

The random amplified polymorphic DNA (RAPD) assay to determine DNA alterations, repair and transgenerational effects in B(a)P exposed Daphnia magna

The random amplified polymorphic DNA (RAPD) is a useful assay for the detection of genotoxin-induced DNA damage and mutations. In this study, we have further evaluated the potential of this assay to measure benzo(a)pyrene [B(a)P]-induced DNA changes, and repair (in kinetic experiments) as well as transgenerational effects in the water fleas, Daphnia magna. The organisms, which reproduce parthenogenetically, were exposed to 50 microg L(-1) B(a)P for 3 or 6 days and were allowed to recover in clean medium for 12 or 9 days, respectively. Qualitative and quantitative changes were observed in RAPD profiles generated not only from the B(a)P exposed Daphnia but also from previously treated organisms during the recovery experiments. The fact that some of the RAPD changes disappeared at the end of both recovery experiments suggested that the DNA effects were fully repaired or reversed. In addition, some of the B(a)P-induced RAPD alterations detected in parental D. magna were also observed in the offspring patterns. This suggested that DNA alterations that occurred in germ cells were probably transmitted to the next cohorts. The present study shows that the RAPD method can be useful to qualitatively assess the kinetics of DNA changes, repair and transgenerational effects and such effects could potentially be linked to survival and reproductive success at higher levels of biological organisation. In addition, the water fleas have efficient capabilities to repair or reverse B(a)P-induced DNA effects. Finally, unrepaired or misrepaired genetic damage induced by genotoxins such as B(a)P could be transmitted to next generations in these parthenogenetically reproducing organisms.

The use of RAPD in ecotoxicology

Toxic compounds may interfere with the genetic constitution of populations, either directly through mutagenic activity, or indirectly via population-mediated processes (i.e. selection, bottleneck). These processes are initiated when toxic compounds reduce the survival and/or fecundity of exposed organisms, either through the accumulation of unfavorable mutations or when they adversely affect the physiology of an organism and/or the environment in which it has to survive. In this review, we describe how the RAPD technique can be applied in an ecotoxicological context, providing information on all direct and indirect routes through which toxicants may affect the genetic structure of populations. Based on RAPD band intensity, gain/loss and band numbers, three major types of RAPD fingerprint analyses are discussed, yielding diagnostic, phenetic and genetic information. Ecotoxicological literature examples demonstrate that, under strictly standardized conditions, the RAPD technique can be a useful tool to preliminary assess toxicological population genetic effects, particularly since this technique is relatively inexpensive and yields information on a large number of loci without having to obtain sequence data for primer design. However, currently only a small fraction of its potential is used in ecotoxicology. Statistical tools and parameters, as used in other RAPD studies, should be applied in ecotoxicological research as well in order to fully exploit the potential of this technique. Finally, due to their random nature, RAPD data often must be considered as preliminary until they are further documented by cloning, sequencing and probing techniques.

Evaluation of the random amplified polymorphic DNA (RAPD) assay for the detection of DNA damage and mutations

The random amplified polymorphic DNA (RAPD) assay and related techniques like the arbitrarily primed polymerase chain reaction (AP-PCR) have been shown to detect genotoxin-induced DNA damage and mutations. The changes occurring in RAPD profiles following genotoxic treatments include variation in band intensity as well as gain or loss of bands. However, the interpretation of the molecular events responsible for differences in the RAPD patterns is not an easy task since different DNA alterations can induce similar type of changes. In this study, we evaluated the effects of a number of DNA alterations on the RAPD profiles. Genomic DNA from different species was digested with restriction enzymes, ultrasonicated, treated with benzo[a]pyrene (B[a]P) diol epoxide (BPDE) and the resulting RAPD profiles were evaluated. In comparison to the enzymatic DNA digestions, sonication caused greater changes in the RAPD patterns and induced a dose-related disappearance of the high molecular weight amplicons. A DNA sample substantially modified with BPDE caused very similar changes but amplicons of low molecular weight were also affected. Appearance of new bands and increase in band intensity were also evident in the RAPD profiles generated by the BPDE-modified DNA. Random mutations occurring in mismatch repair-deficient strains did not cause any changes in the banding patterns whereas a single base change in 10-mer primers produced substantial differences. Finally, further research is required to better understand the potential and limitations of the RAPD assay for the detection of DNA damage and mutations.

4-n-Nonylphenol and 17-beta estradiol may induce common DNA effects in developing barnacle larvae

There is a growing concern over the potential effects of environmental endocrine disrupters on both human and wildlife populations. However, to date, minimal research has been conducted to determine the effect of estrogens and xenoestrogens at the DNA level. In this study, we used the random amplified polymorphic DNA (RAPD) assay to evaluate the effects on the genomic DNA of barnacle larvae that had been exposed to 17beta-estradiol (E2) and low concentrations of 4-n-nonylphenol (NP). DNA effects include DNA damage as well as mutations and possibly other effects at the DNA level that can be induced by chemical or physical agents that directly and/or indirectly interact with genomic DNA. Not only did exposure to NP and E2 induce changes in RAPD profiles in the exposed barnacle larvae when compared to control patterns, but also, and more importantly, there were similarities in the RAPD modifications in the exposed populations that had been treated to either chemical. We propose that NP and E2 induced some common DNA effects in barnacle larvae and that these specific modifications in RAPD patterns may arise as a consequence of hot spot DNA damage (e.g. DNA adducts) and/or mutations (point mutations or genomic rearrangements). This could help to explain how xenoestrogens mimic the effects produced by natural estrogens. In conclusion, in the field of endocrine disruption, the study of DNA effects induced by estrogens and/or xenoestrogens warrants further investigation. Indeed, changes at the DNA levcl may be the precursors of some of the numerous effects reported at higher levels of biological organisation such as the feminization of males, developmental abnormalities, and infertility.