Modifications Of DNA Structure Research Articles

Insight Into Factors Governing Formation, Synthesis and Stereochemical Configuration of DNA Adducts Formed by Mitomycins.

Mitomycin C, (MC), an antitumor drug used in the clinics, is a DNA alkylating agent. Inert in its native form, MC is reduced to reactive mitosenes in cellulo which undergo nucleophilic attack by DNA bases to form monoadducts as well as interstrand crosslinks (ICLs). These properties constitute the molecular basis for the cytotoxic effects of the drug. The mechanism of DNA alkylation by mitomycins has been studied for the past 30 years and, until recently, the consensus was that drugs of the mitomycins family mainly target CpG sequences in DNA. However, that paradigm was recently challenged. Here, we relate the latest research on both MC and dicarbamoylmitomycin C (DMC), a synthetic derivative of MC which has been used to investigate the regioselectivity of mitomycins DNA alkylation as well as the relationship between mitomycins reductive activation pathways and DNA adducts stereochemical configuration. We also review the different synthetic routes to access mitomycins nucleoside adducts and oligonucleotides containing MC/DMC DNA adducts located at a single position. Finally, we briefly describe the DNA structural modifications induced by MC and DMC adducts and how site specifically modified oligonucleotides have been used to elucidate the role each adduct plays in the drugs cytotoxicity.

Regular, Intense Exercise Training as a Healthy Aging Lifestyle Strategy: Preventing DNA Damage, Telomere Shortening and Adverse DNA Methylation Changes Over a Lifetime.

Exercise training is one of the few therapeutic interventions that improves health span by delaying the onset of age-related diseases and preventing early death. The length of telomeres, the 5′-TTAGGGn-3′ tandem repeats at the ends of mammalian chromosomes, is one of the main indicators of biological age. Telomeres undergo shortening with each cellular division. This subsequently leads to alterations in the expression of several genes that encode vital proteins with critical functions in many tissues throughout the body, and ultimately impacts cardiovascular, immune and muscle physiology. The sub-telomeric DNA is comprised of heavily methylated, heterochromatin. Methylation and histone acetylation are two of the most well-studied examples of the epigenetic modifications that occur on histone proteins. DNA methylation is the type of epigenetic modification that alters gene expression without modifying gene sequence. Although diet, genetic predisposition and a healthy lifestyle seem to alter DNA methylation and telomere length (TL), recent evidence suggests that training status or physical fitness are some of the major factors that control DNA structural modifications. In fact, TL is positively associated with cardiorespiratory fitness, physical activity level (sedentary, active, moderately trained, or elite) and training intensity, but is shorter in over-trained athletes. Similarly, somatic cells are vulnerable to exercise-induced epigenetic modification, including DNA methylation. Exercise-training load, however, depends on intensity and volume (duration and frequency). Training load-dependent responses in genomic profiles could underpin the discordant physiological and physical responses to exercise. In the current review, we will discuss the role of various forms of exercise training in the regulation of DNA damage, TL and DNA methylation status in humans, to provide an update on the influence exercise training has on biological aging.

Modification of DNA structure by reactive nitrogen species as a result of 2-methoxyestradiol–induced neuronal nitric oxide synthase uncoupling in metastatic osteosarcoma cells

2-methoxyestradiol (2-ME) is a physiological anticancer compound, metabolite of 17β-estradiol. Previously, our group evidenced that from mechanistic point of view one of anticancer mechanisms of action of 2-ME is specific induction and nuclear hijacking of neuronal nitric oxide synthase (nNOS), resulting in local generation of nitro-oxidative stress and finally, cancer cell death.The current study aims to establish the substantial mechanism of generation of reactive nitrogen species by 2-ME. We further achieved to identify the specific reactive nitrogen species involved in DNA-damaging mechanism of 2-ME.The study was performed using metastatic osteosarcoma 143B cells. We detected the release of biologically active (free) nitric oxide (•NO) with concurrent measurements of peroxynitrite (ONOO−) in real time in a single cell of 143B cell line by using •NO/ONOO− sensitive microsensors after stimulation with calcium ionophore. Detection of nitrogen dioxide (•NO2) and determination of chemical rate constants were carried out by a stopped-flow technique. The affinity of reactive nitrogen species toward the guanine base of DNA was evaluated by density functional theory calculations. Expression and localization of nuclear factor NF-kB was determined using imaging cytometry, while cell viability assay was evaluated by MTT assay.Herein, we presented that 2-ME triggers pro-apoptotic signalling cascade by increasing cellular reactive nitrogen species overproduction – a result of enzymatic uncoupling of increased nNOS protein levels. In particular, we proved that ONOO− and •NO2 directly formed from peroxynitrous acid (ONOOH) and/or by auto-oxidation of •NO, are inducers of DNA damage in anticancer mechanism of 2-ME. Specifically, the affinity of reactive nitrogen species toward the guanine base of DNA, evaluated by density functional theory calculations, decreased in the order: ONOOH > ONOO− > •NO2 > •NO.Therefore, we propose to consider the specific inducers of nNOS as an effective tool in the field of chemotherapy.

Alterations to DNA structure as a cause of expression modifications of selected genes of known intrauterine-growth-restriction-association shared by chosen species - a review.

The review aimed at searching for DNA structure markers of epigenetic modifications leading to intrauterine growth restriction (IUGR) in three livestock species, mouse and human. IUGR affects mammals by harming their wellbeing and the profitability of breeding enterprises. Of the livestock species, we chose cow, pig and sheep owing to there being many reports on the epigenetics of IUGR. IUGR investigations in human and mouse are particularly numerous, as we are interested in our own wellbeing and the mouse is a model species. We decided to focus on five genes (Igf2r, Igf2, H19, Peg3 and Mest) of known IUGR association, reported in all of those species. Despite the abundance of papers on IUGR, naturally occurring mutations responsible for epigenetic modifications have been described only in human and cow. The effect of induced DNA structural modifications upon epigenetics has been described in mouse and pig. One paper regarding mouse was chosen from among those describing DNA modifications performed to obtain parthenogenetic progeny. Papers regarding pig parthenogenetic progeny described the epigenetics of genes involved in foetal development, with no interference with the genome structure. No reports on DNA modifications altering IUGR epigenetics in sheep were found. Only environmental effects were studied and we could not conclude from the experiment designs whether the gene setup could affect the expression of involved genes, as different populations were not included or not specified within particular experiments. Apparently, DNA markers of IUGR epigenetics exist. It has been reported that the small number of them, occurring naturally, may result from neglecting existing evidence of such selection or health status forecasting markers.

Biological Function of Changes in RNA Metabolism in Plant Adaptation to Abiotic Stress.

Plant growth and productivity are greatly impacted by environmental stresses. Therefore, plants have evolved various sophisticated mechanisms for adaptation to nonoptimal environments. Recent studies using RNA metabolism-related mutants have revealed that RNA processing, RNA decay and RNA stability play an important role in regulating gene expression at a post-transcriptional level in response to abiotic stresses. Studies indicate that RNA metabolism is a unified network, and modification of stress adaptation-related transcripts at multiple steps of RNA metabolism is necessary to control abiotic stress-related gene expression. Recent studies have also demonstrated the important role of noncoding RNAs (ncRNAs) in regulating abiotic stress-related gene expression and revealed their involvement in various biological functions through their regulation of DNA methylation, DNA structural modifications, histone modifications and RNA-RNA interactions. ncRNAs regulate mRNA transcription and their synthesis is affected by mRNA processing and degradation. In the present review, recent findings pertaining to the role of the metabolic regulation of mRNAs and ncRNAs in abiotic stress adaptation are summarized and discussed.

The Involvement of Long Noncoding RNAs in Response to Plant Stress.

Plant growth and productivity are greatly impacted by environmental stresses. Therefore, plants have evolved mechanisms which allow them to adapt to abiotic stresses through alterations in gene expression and metabolism. In recent years, studies have investigated the role of long noncoding RNA (lncRNA) in regulating gene expression in plants and characterized their involvement in various biological functions through their regulation of DNA methylation, DNA structural modifications, histone modifications, and RNA-RNA interactions. Genome-wide transcriptome analyses have identified various types of noncoding RNAs (ncRNAs) that respond to abiotic stress. These ncRNAs are in addition to the well-known housekeeping ncRNAs, such as rRNAs, tRNAs, snoRNAs, and snRNAs. In this review, recent research pertaining to the role of lncRNAs in the response of plants to abiotic stress is summarized and discussed.

Abstract 3941: Heparan sulfate, a new target for platinum in metastatic TNBC

Abstract Heparan sulfate (HS) are linear polysaccharides conjugated to proteins, heparan sulfate proteoglycans (HSPGs), located on the cell surface and extracellular matrix. The HS chains display varying degrees of sulfation. These sulfate clusters mediate the interaction of polynuclear platinum complexes (PPCs) with HSPG through a “sulfate clamp.” Such PPC-HS interactions can be conceptualized as “polyarginine” mimics. Strong HS-PPC binding protects the oligosaccharide against sulfate loss through metalloshielding. The biological consequences of PPCs metalloshielding HS will in principle affect HS interactions with relevant enzymes and proteins such as heparanase and growth factors, similar in concept to inhibition of DNA-protein binding through modification of DNA structure and conformation. HSPGs, associated growth factors, and heparanase promote tumor progression by facilitating invasion, angiogenesis, and metastasis. High heparanase expression correlates with increased metastatic potential and poor clinical prognosis. PPC-HS interactions inhibit cleavage of a model pentasaccharide by heparanase and further modulated bFGF binding to HS, and bFGF-induced migration and signaling in colon cancer cells. The end-point of functional modulation of HS interactions is inhibition of angiogenesis and metastasis. We report proof-of-principle of strong in vivo anti-metastatic activity of PPCs in triple negative breast cancer (TNBC) models. Further, we examine the anti-metastatic and anti-angiogenic effects of PPC-HS metalloshielding in these in vivo models through multiple growth factor signaling pathways (bFGF, HB-EGF, VEGF), and heparanase activity in breast cancer and endothelial cells. PPCs represent a novel class of intrinsically dual-function agents combining platinum cytotoxicity through DNA targeting with anti-angiogenic effects through glycan targeting. Chicago 14-17 April 2018 Citation Format: Samantha J. Katner, James D. Hampton, Erica J. Peterson, Eriko Katsuta, Megan R. Sayyad, Kazuaki Takabe, Jennifer Koblinski, Nicholas P. Farrell. Heparan sulfate, a new target for platinum in metastatic TNBC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3941.

Bacterial-Chromatin Structural Proteins Regulate the Bimodal Expression of the Locus of Enterocyte Effacement (LEE) Pathogenicity Island in Enteropathogenic Escherichia coli.

ABSTRACTIn enteropathogenic Escherichia coli (EPEC), the locus of enterocyte effacement (LEE) encodes a type 3 secretion system (T3SS) essential for pathogenesis. This pathogenicity island comprises five major operons (LEE1 to LEE5), with the LEE5 operon encoding T3SS effectors involved in the intimate adherence of bacteria to enterocytes. The first operon, LEE1, encodes Ler (LEE-encoded regulator), an H-NS (nucleoid structuring protein) paralog that alleviates the LEE H-NS silencing. We observed that the LEE5 and LEE1 promoters present a bimodal expression pattern, depending on environmental stimuli. One key regulator of bimodal LEE1 and LEE5 expression is ler expression, which fluctuates in response to different growth conditions. Under conditions in vitro considered to be equivalent to nonoptimal conditions for virulence, the opposing regulatory effects of H-NS and Ler can lead to the emergence of two bacterial subpopulations. H-NS and Ler share nucleation binding sites in the LEE5 promoter region, but H-NS binding results in local DNA structural modifications distinct from those generated through Ler binding, at least in vitro. Thus, we show how two nucleoid-binding proteins can contribute to the epigenetic regulation of bacterial virulence and lead to opposing bacterial fates. This finding implicates for the first time bacterial-chromatin structural proteins in the bimodal regulation of gene expression.

Abstract 17: Anti-metastatic platinum through glycan targeting in breast cancer

Abstract The high affinity of polynuclear platinum compounds (PPCs) for heparan sulfate (HS) is mediated through a “sulfate clamp” and PPC interactions can be conceptualized as “polyarginine” mimics. Strong HS-PPC binding protects the oligosaccharide against sulfate loss through metalloshielding.1 Metalloshielding will in principle affect HS interactions with relevant enzymes and proteins such as heparanase and growth factors, similar in concept to inhibition of DNA-protein binding through modification of DNA structure and conformation.2 PPCs inhibit cleavage of a model pentasaccharide by heparanase and further modulate bFGF binding to HS, and bFGF-induced migration and signaling in colon cancer cells.3 The end-point of functional modulation of HS interactions is inhibition of angiogenesis and metastasis.3 Following proof-of-principle of strong in vivo anti-metastatic activity of PPCs in clinically relevant breast cancer models,4 this contribution examines the underlying mechanism of platinums as anti-metastatic agents. We report on the cellular effects of PPC-HS metalloshielding on multiple growth factor signaling pathways (bFGF, HB-EGF) and specific syndecan (Sdc)-dependent signaling in breast cancer. Coupled with previously demonstrated DNA binding, PPCs represent intrinsically dual- function agents combining platinum cytotoxicity with anti-angiogenic effects derived from first principles through glycan targeting. [1] Mangrum, J.B., Engelmann, B.J., Peterson, E.J., Ryan, J.J., Berners-Price, S.J., Farrell, N.P. Chemical Communications 2014, 50, 4056-4058. [2] Chiodelli, P., Bugatti, A., Urbinati, C., Rusnati, M. Molecules 2015, 20, 6342-6388. [3] Peterson, E.J., Daniel, A.G., Katner, S.J., Bohlmann, L., Chang,C., Bezos, A., Parish, C.R., von Itzstein, M., Berners-Price, S.J., Farrell, N.P. Chem. Sci. 2016, DOI: 10.1039/C6SC02515C. [4] E. Katsuta, S. Demasi, S. Katner, H. Aoki, E. Peterson, E., N.P. Farrell and K. Takabe. (2016). Proc. AACR New Orleans, LA. Abstract #3064. DC 1-5 April 2017 Citation Format: Samantha J. Katner, Erica Peterson J. Peterson, Eriko Katsuta, Stephanie C. DeMasi, Jennifer Koblinski, Kazuaki Takabe, Nicholas P. Farrell. Anti-metastatic platinum through glycan targeting in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 17. doi:10.1158/1538-7445.AM2017-17

The Roles of ROS in Cancer Heterogeneity and Therapy.

Cancer comprises a group of heterogeneous diseases encompassing high rates of morbidity and mortality. Heterogeneity, which is a hallmark of cancer, is one of the main factors related to resistance to chemotherapeutic agents leading to poor prognosis. Heterogeneity is profoundly affected by increasing levels of ROS. Under low concentrations, ROS may function as signaling molecules favoring tumorigenesis and heterogeneity, while under high ROS concentrations, these species may work as cancer modulators due to their deleterious, genotoxic or even proapoptotic effect on cancer cells. This double-edged sword effect represented by ROS relies on their ability to cause genetic and epigenetic modifications in DNA structure. Antitumor therapeutic approaches may use molecules that prevent the ROS formation precluding carcinogenesis or use chemical agents that promote a sudden increase of ROS causing considerable oxidative stress inside tumor mass. Therefore, herein, we review what ROS are and how they are produced in normal and in cancer cells while providing an argumentative discussion about their role in cancer pathophysiology. We also describe the various sources of ROS in cancer and their role in tumor heterogeneity. Further, we also discuss some therapeutic strategies from the current landscape of cancer heterogeneity, ROS modulation, or ROS production.

Fermented papaya preparation modulates the progression of N-methyl-N-nitrosourea induced hepatocellular carcinoma in Balb/c mice

Aim and main methodThe medicinal properties of fermented papaya preparation (FPP) derived from Carica papaya fruit was investigated in order to determine its ability to modulate the progression of N-methyl-N-nitrosourea induced hepatocellular carcinoma in Balb/c mice. Key findingsAs well as reducing the physical symptoms associated with N-methyl-N-nitrosourea (MNU)-induced hepatocellular carcinoma, supplementation of Balb/c mice with 500mg FPP/kg BW for 92days normalized the blood cell count, led to an increased activity of several key antioxidant enzymes (SOD: +20%, CAT: +81%, GPx: +66.1%, GR: +54.4%; P<0.001 vs. MNU control), increased the ferrous reducing antioxidant potential (+36.7%, P<0.001 vs. MNU control) and reduced the extent of lipid peroxidation in the liver by 44.3% (P<0.001 vs. MNU control). SignificanceResults demonstrated the ability of FPP to preserve the integrity of liver against oxidative damage and protect hepatocytes against irreversible DNA structural modifications induced by MNU, highlighting its potential role as an immune-defense modulator during hepatocarcinoma.

Tropically adapted cattle of Africa: perspectives on potential role of copy number variations

Africa is host to diverse and locally adapted cattle breeds that are expected to survive the harsh and extreme tropical environments associated with diseases and parasite infections, heat stress and episodes of feed and water scarcity. Genomic copy number variations (CNVs) are considered to be primary role players in cattle breed formation and adaptation where isolation and genetic drift together with subsequent mutations have created an enormous diversity of local populations. CNVs are modifications in DNA structure comprising deletions, duplications and insertions that are >1kb in size. Despite attracting much attention, the frequency and pattern of bovine CNV events, especially in African cattle breeds, are for the most part largely unknown. Characterization of genetic variation in the indigenous cattle of Africa will be a vital step toward dissecting the molecular mechanisms underlying phenotypic variation and local adaptation. This review therefore aims to describe the current knowledge regarding bovine CNVs and the implications and potentials they encompass for dissecting genetic adaptation and the genotypic skeleton of tropical African cattle populations.

Genomic population structure and prevalence of copy number variations in South African Nguni cattle.

BackgroundCopy number variations (CNVs) are modifications in DNA structure comprising of deletions, duplications, insertions and complex multi-site variants. Although CNVs are proven to be involved in a variety of phenotypic discrepancies, the full extent and consequence of CNVs is yet to be understood. To date, no such genomic characterization has been performed in indigenous South African Nguni cattle. Nguni cattle are recognized for their ability to sustain harsh environmental conditions while exhibiting enhanced resistance to disease and parasites and are thought to comprise of up to nine different ecotypes.MethodsIllumina BovineSNP50 Beadchip data was utilized to investigate genomic population structure and the prevalence of CNVs in 492 South African Nguni cattle. PLINK, ADMIXTURE, R, gPLINK and Haploview software was utilized for quality control, population structure and haplotype block determination. PennCNV hidden Markov model identified CNVs and genes contained within and 10 Mb downstream from reported CNVs. PANTHER and Ensembl databases were subsequently utilized for gene annotation analyses.ResultsPopulation structure analyses on Nguni cattle revealed 5 sub-populations with a possible sub-structure evident at K equal to 8. Four hundred and thirty three CNVs that formed 334 CNVRs ranging from 30 kb to 1 Mb in size are reported. Only 231 of the 492 animals demonstrated CNVRs. Two hundred and eighty nine genes were observed within CNVRs identified. Of these 149, 28, 44, 2 and 14 genes were unique to sub-populations A, B, C, D and E respectively. Gene ontology analyses demonstrated a number of pathways to be represented by respective genes, including immune response, response to abiotic stress and biological regulation processess.ConclusionsCNVs may explain part of the phenotypic diversity and the enhanced adaptation evident in Nguni cattle. Genes involved in a number of cellular components, biological processes and molecular functions are reported within CNVRs identified. The significance of such CNVRs and the possible effect thereof needs to be ascertained and may hold interesting insight into the functional and adaptive consequence of CNVs in cattle.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-2122-z) contains supplementary material, which is available to authorized users.

In situ evaluation of gemcitabine–DNA interaction using a DNA-electrochemical biosensor

The electrochemical behaviour of the cytosine nucleoside analogue and anti-cancer drug gemcitabine (GEM) was investigated at glassy carbon electrode, using cyclic, differential pulse and square wave voltammetry, in different pH supporting electrolytes, and no electrochemical redox process was observed. The evaluation of the interaction between GEM and DNA in incubated solutions and using the DNA-electrochemical biosensor was studied. The DNA structural modifications and damage were electrochemically detected following the changes in the oxidation peaks of guanosine and adenosine residues and the occurrence of the free guanine residues electrochemical signal. The DNA–GEM interaction mechanism occurred in two sequential steps. The initial process was independent of the DNA sequence and led to the condensation/aggregation of the DNA strands, producing rigid structures, which favoured a second step, in which the guanine hydrogen atoms, participating in the C–G base pair, interacted with the GEM ribose moiety fluorine atoms.

Abstract 2768: Molecular properties and antiproliferative activity against tumor cells of a new poly-alkylamino-bis-maltolic synthetic molecule (maltonis).

Abstract Introduction Hydroxypyrones are highly versatile molecules and several members of this family, both alone and in combination with metals, were found to exert anti-proliferative activities against a wide range of tumor cells. In this study, we show the anti-tumor potential of the prototype of new molecules belonging to the family of hydroxypyrones, named maltonis [4(N),10(N)-bis[(3- hydroxy-4-pyron-2-yl)methyl]-1,7-dimethyl-1,4,7,10-tetraazacyclododecane], in different tumor cell lines (derived from both hematopoietic and solid human tumors). Methods and Results We examined the potential of maltonis to induce, in cell-free assays, covalent modifications of DNA structure, together with anticancer activities (cell growth inhibition, cell cycle perturbations, effects on programmed cell death). The cellular response to maltonis treatment was assessed also at the molecular level by evaluation of the transcript level of genes involved in cell cycle and programmed cell death regulation. The possible induction of a maltonis-mediated DNA damage response was investigated monitoring the histone H2AX phosphorylation (γH2AX). Sarcoma cell lines appeared to be particularly sensitive to maltonis in in vitro assays. Consistently, preliminary in vivo experiments reported a cytostatic effect of maltonis, monitoring a consistent reduction of the neoplastic lesions, when intra-tumor injected at doses of 20/40 mg/kg (for two weeks) in a xenograft model of Ewing Sarcoma. However, a range of different levels of sensitivity was observed in the different histotypes (osteosarcoma, Ewing sarcoma and rhabdomyosarcoma) and among cell lines, indicating the need of further studies to identify markers of efficacy. Conclusions Taken together, these results show that maltonis appears to be a good candidate for sarcoma treatment. It induces complex DNA structural modifications, which need to be further analysed in order to clarify mechanisms of action and efficacy of this new drug. Grants from: AIRC 10452 and Ministry of Health_RF2008 to KS; A.S.S.O., PRIN 2008 and PRIN 2009 to MF and VF. Citation Format: Maria Cristina Manara, Mirco Fanelli, Stefano Amatori, Clara Guerzoni, Lorena Landuzzi, Pier-Luigi Lollini, Luca Giorgi, Vieri Fusi, Katia Scotlandi. Molecular properties and antiproliferative activity against tumor cells of a new poly-alkylamino-bis-maltolic synthetic molecule (maltonis). [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2768. doi:10.1158/1538-7445.AM2013-2768

Impact of the toxic dinoflagellateAlexandrium catenellaon Pacific oyster reproductive output: application of flow cytometry assays on spermatozoa

The toxic dinoflagellate Alexandrium catenella recurrently blooms on the coasts of France and produces Paralytic Shellfish Toxins (PSTs) that accumulate in bivalves. These toxins can affect various physiological functions including reproduction. The present study aims to validate measurements of sperm viability, DNA content and mitochondrial membrane potential in Pacific oyster Crassostrea gigas using flow cytometry coupled with fluorescent markers, and to use these measurements to assess the cellular parameters of sperm from Pacific oysters exposed to A. catenella. These parameters may influence fertilization, embryogenesis and larval development in free-spawning shellfish. Sperm viability and DNA content estimation were assessed using SYBR-14, which only penetrates cells with intact membranes. Cell mortality was measured with propidium iodide (PI), which penetrates cells with membrane damage. Mitochondrial membrane potential, used as an estimate of mitochondrial function, was measured using JC-1 dye, which selectively enters into mitochondria and reversibly changes colour from green to orange as the membrane potential increases. To assess the effect of toxic algae on oyster sperm, broodstock (ripe oysters) were fed toxic (A. catenella) or non toxic (Heterocapsa triquetra) dinoflagellates at 250 cell ml-1 for 9 days. After this exposure period, mature oysters were stripped and cellular responses of sperm analysed. Average DNA staining, as measured by SYBR-14, appeared lower and more variable in gametes from A. catenella-exposed oysters than in those from control oysters fed H. triquetra. Additionally, mitochondrial membrane potential of sperm from A. catenella-exposed oysters was significantly higher (1.5 fold) than that of sperm produced by oysters fed H. triquetra. Both the increase of mitochondrial membrane potential and the modification of DNA structure can be expected to impact spermatozoa ability to fertilize oocytes and could thus impact related reproductive processes.

Interactions of Gold Nanoparticles with DNA: Interplay of Sequence, Ligands Charge and Polarity

DNA template can trigger the self-assembly of metal or semiconductor nanoparticles into programmable molecular architectures. The performance of DNA-nanoparticle system strongly depends on the size and ligand chemistry of nanoparticles. We performed molecular dynamics simulations to investigate the effect of colloidal gold nanoparticle (GNP) ligands charge and polarity on the ability to bind DNA molecules. We tailored the surface of GNP by introducing different terminal functionality to thiolated ligands, such as hydrophobic, polar and charged groups. We found that uncharged GNPs and GNPs with cationic ligand charge density of less than 10% can only bind to the minor groove of DNA. Whereas GNPs with ligands charge density of higher than 10% can bind to major or minor groove. Binding to major groove result in significant distortion and wrapping of DNA around the GNP. The distortions of the DNA helical structure strongly depends on the ligand charge density. Also at higher nanoparticle concentration and low charge densities, the ligand hydrophobicity can disrupt the hydrogen bonding between base pairs of DNA strands and leads to unwinding of DNA helix. We observed that by tuning the cationic charge density and polarity of GNP we can control the binding modes and DNA structural modifications.

Epigenetic epidemiology of age-related diseases

Many studies have shown that our organism is mostly sensitive to different influences in pre- and postnatal periods of ontogenesis. During the critical periods of maturation, these influences induce changes in the organism that relate to ontogenetic plasticity and lead to permanent changes in structure and function of different organ systems of the organism. It is suggested that the main molecular mechanisms of so-called "ontogenetic programming" are based on changes that occur on the epigenetic level, including changes in the genetic expression not connected with modifications of DNA structure. The present review deals with experimental and epidemiologic evidences of the role of epigenetic processes in aging and determination of susceptibility to some age-related diseases, such as cancer, cardiovascular and neurodegenerative diseases, and insulin-independent diabetes.

Malten, a new synthetic molecule showing in vitro antiproliferative activity against tumour cells and induction of complex DNA structural alterations

Background:Hydroxypyrones represent several classes of molecules known for their high synthetic versatility. This family of molecules shows several interesting pharmaceutical activities and is considered as a promising source of new antineoplastic compounds.Methods:In the quest to identify new potential anticancer agents, a new maltol (3-hydroxy-2-methyl-4-pyrone)-derived molecule, named malten (N,N′-bis((3-hydroxy-4-pyron-2-yl)methyl)-N,N′-dimethylethylendiamine), has been synthesised and analysed at both biological and molecular levels for its antiproliferative activity in eight tumour cell lines.Results:Malten exposure led to a dose-dependent reduction in cell survival in all the neoplastic models studied. Sublethal concentrations of malten induce profound cell cycle changes, particularly affecting the S and/or G2-M phases, whereas exposure to lethal doses causes the induction of programmed cell death. The molecular response to malten was also investigated in JURKAT and U937 cells. It showed the modulation of genes having key roles in cell cycle progression and apoptosis. Finally, as part of the effort to clarify the action mechanism, we showed that malten is able to impair DNA electrophoretic mobility and drastically reduce both PCR amplificability and fragmentation susceptibility of DNA.Conclusion:Taken together, these results show that malten may exert its antiproliferative activity through the induction of complex DNA structural modifications. This evidence, together with the high synthetic versatility of maltol-derived compounds, makes malten an interesting molecular scaffold for the future design of new potential anticancer agents.

Plasma immersion low-energy-ion bombardment of naked DNA

Low-energy ion irradiation of DNA is of great interest in fundamental studies on mechanisms involved in low-energy ion beam induced mutation, plasma sterilization and ionizing radiation risk of lives. We have made the first attempt to use low-energy ions in plasma immersion ion implantation and deposition (PIII-D) to bombard naked plasmid DNA to investigate effect on the DNA structural modification and mutation. Naked DNA samples were immersed in either argon or nitrogen plasma in low pressure and then bombarded by ions in the plasma in different conditions, namely, using a low bias of − 2.5 kV, or no bias, in which the sample holder was either grounded or not grounded, to low fluences of 1011, 1012 and 1013 ions/cm2. The plasma-treated DNA was transferred into bacteria E. coli. Mutation was found from the bacterial colonies when DNA was bombarded with the bias, but not found when DNA was bombarded without a bias. This indicates that ions with energy only at the order of the thermal energy cannot induce mutation but with low-energy of keV the ions can. Subsequent gel electrophoresis and DNA sequencing analyzed the DNA structural changes and found certain modifications in the DNA forms.