1 5184 114 PREMATURE CHROMOSOME CONDENSATION ASSAY TO STUDY INFLUENCE OF HIGH-LEVEL NATURAL RADIATION ON THE INITIAL DNA DOUBLE STRAND BREAK REPAIR IN HUMAN G(0) LYMPHOCYTES. THE INHERENT CAPACITY OF INDIVIDUALS TO EFFICIENTLY REPAIR IONIZING RADIATION INDUCED DNA DOUBLE STRAND BREAKS (DSBS) MAY BE INHERITED, HOWEVER, IT IS INFLUENCED BY SEVERAL EPIGENETIC AND ENVIRONMENTAL FACTORS. A PILOT STUDY TESTED WHETHER CHRONIC LOW DOSE NATURAL RADIATION EXPOSURE INFLUENCES THE REJOINING OF INITIAL DNA DSBS INDUCED BY A 2 GY GAMMA-IRRADIATION IN 22 INDIVIDUALS FROM HIGH (>1.5 MGY/YEAR) AND NORMAL (1 WEEK RESULTED IN LONGER BODY LENGTHS IN THEIR LARVAL OFFSPRING. TIME TO LOSS OF EQUILIBRIUM IN SEVERE HYPOXIA (I.E. HYPOXIC RESISTANCE) IN CONTROL LARVAE DECREASED FROM 6 TO 12 D.P.F., REMAINING CONSTANT THEREAFTER. NOTABLY, HYPOXIC RESISTANCE FROM 6 TO 18 D.P.F. WAS ~15% LOWER IN LARVAE WHOSE PARENTS WERE EXPOSED TO JUST 1 WEEK OF CHRONIC HYPOXIA, BUT RESISTANCE WAS SIGNIFICANTLY INCREASED BY ~24-30% IN 6-18 D.P.F. LARVAE FROM ADULTS EXPOSED TO 2, 3 OR 4 WEEKS OF HYPOXIA. CT(MIN) (~10-12 DEGREES C) AND CT(MAX) (~39.5 DEGREES C) WERE UNCHANGED BY PARENTAL HYPOXIC EXPOSURE. THIS STUDY DEMONSTRATES THAT PARENTAL HYPOXIC EXPOSURE IN ADULT ZEBRAFISH HAS PROFOUND EPIGENETIC EFFECTS ON THE MORPHOLOGICAL AND PHYSIOLOGICAL PHENOTYPE OF THEIR OFFSPRING. 2012 12 1835 30 EFFECTS OF NON-HUMAN SPECIES IRRADIATION AFTER THE CHERNOBYL NPP ACCIDENT. THE AREA AFFECTED BY THE CHERNOBYL NUCLEAR POWER PLANT ACCIDENT IN 1986 HAS BECOME A UNIQUE TEST SITE WHERE LONG-TERM ECOLOGICAL AND BIOLOGICAL CONSEQUENCES OF A DRASTIC CHANGE IN A RANGE OF ENVIRONMENTAL FACTORS AS WELL AS TRENDS AND INTENSITY OF SELECTION ARE STUDIED IN NATURAL SETTINGS. THE CONSEQUENCES OF THE CHERNOBYL ACCIDENT FOR BIOTA VARIED FROM AN ENHANCED RATE OF MUTAGENESIS TO DAMAGE AT THE ECOSYSTEM LEVEL. THE REVIEW COMPREHENSIVELY BRINGS TOGETHER KEY DATA OF THE LONG-TERM STUDIES OF BIOLOGICAL EFFECTS IN PLANTS AND ANIMALS INHABITING OVER 20 YEARS THE CHERNOBYL NPP ZONE. THE SEVERITY OF RADIATION EFFECTS WAS STRONGLY DEPENDENT ON THE DOSE RECEIVED IN THE EARLY PERIOD AFTER THE ACCIDENT. THE MOST EXPOSED PHYTOCENOSES AND SOIL ANIMALS' COMMUNITIES EXHIBITED DOSE DEPENDENT ALTERATIONS IN THE SPECIES COMPOSITION AND REDUCTION IN BIOLOGICAL DIVERSITY. ON THE OTHER HAND, NO DECREASE IN NUMBERS OR TAXONOMIC DIVERSITY OF SMALL MAMMALS EVEN IN THE MOST RADIOACTIVE HABITAT WAS SHOWN. IN A MAJORITY OF THE STUDIES, IN BOTH PLANT AND ANIMAL POPULATIONS FROM THE CHERNOBYL ZONE, IN THE FIRST YEARS AFTER THE ACCIDENT HIGH INCREASES IN MUTATION RATES WERE DOCUMENTED. IN MOST CASES THE DOSE-EFFECT RELATIONSHIPS WERE NONLINEAR AND THE MUTATION RATES PER UNIT DOSE WERE HIGHER AT LOW DOSES AND DOSE RATES. IN SUBSEQUENT YEARS A DECLINE IN THE RADIATION BACKGROUND RATE OCCURRED FASTER THAN REDUCTION IN THE MUTATION RATE. PLANT AND ANIMAL POPULATIONS HAVE SHOWN SIGNS OF ADAPTATION TO CHRONIC EXPOSURE. IN ADAPTATION TO THE ENHANCED LEVEL OF EXPOSURE AN ESSENTIAL ROLE OF EPIGENETIC MECHANISMS OF GENE EXPRESSION REGULATION WAS SHOWN. BASED ON THE CHERNOBYL NPP ACCIDENT STUDIES, IN THE PRESENT REVIEW ATTEMPTS WERE MADE TO ASSESS MINIMUM DOSES AT WHICH ECOLOGICAL AND BIOLOGICAL EFFECTS WERE OBSERVED. 2008 13 3225 25 HELICOBACTER PYLORI INFECTION INTRODUCES DNA DOUBLE-STRAND BREAKS IN HOST CELLS. GASTRIC CANCER IS AN INFLAMMATION-RELATED MALIGNANCY RELATED TO LONG-STANDING ACUTE AND CHRONIC INFLAMMATION CAUSED BY INFECTION WITH THE HUMAN BACTERIAL PATHOGEN HELICOBACTER PYLORI. INFLAMMATION CAN RESULT IN GENOMIC INSTABILITY. HOWEVER, THERE ARE CONSIDERABLE DATA THAT H. PYLORI ITSELF CAN ALSO PRODUCE GENOMIC INSTABILITY BOTH DIRECTLY AND THROUGH EPIGENETIC PATHWAYS. OVERALL, THE MECHANISMS OF H. PYLORI-INDUCED HOST GENOMIC INSTABILITIES REMAIN POORLY UNDERSTOOD. WE USED MICROARRAY SCREENING OF H. PYLORI-INFECTED HUMAN GASTRIC BIOPSY SPECIMENS TO IDENTIFY CANDIDATE GENES INVOLVED IN H. PYLORI-INDUCED HOST GENOMIC INSTABILITIES. WE FOUND UPREGULATION OF ATM EXPRESSION IN VIVO IN GASTRIC MUCOSAL CELLS INFECTED WITH H. PYLORI. USING GASTRIC CANCER CELL LINES, WE CONFIRMED THAT THE H. PYLORI-RELATED ACTIVATION OF ATM WAS DUE TO THE ACCUMULATION OF DNA DOUBLE-STRAND BREAKS (DSBS). DSBS WERE OBSERVED FOLLOWING INFECTION WITH BOTH CAG PATHOGENICITY ISLAND (PAI)-POSITIVE AND -NEGATIVE STRAINS, BUT THE EFFECT WAS MORE ROBUST WITH CAG PAI-POSITIVE STRAINS. THESE RESULTS ARE CONSISTENT WITH THE FACT THAT INFECTIONS WITH BOTH CAG PAI-POSITIVE AND -NEGATIVE STRAINS ARE ASSOCIATED WITH GASTRIC CARCINOGENESIS, BUT THE RISK IS HIGHER IN INDIVIDUALS INFECTED WITH CAG PAI-POSITIVE STRAINS. 2014 14 3040 27 GENOME HYPERMETHYLATION IN PINUS SILVESTRIS OF CHERNOBYL--A MECHANISM FOR RADIATION ADAPTATION? ADAPTATION IS A COMPLEX PROCESS BY WHICH POPULATIONS OF ORGANISMS RESPOND TO LONG-TERM ENVIRONMENTAL STRESSES BY PERMANENT GENETIC CHANGE. HERE WE PRESENT DATA FROM THE NATURAL "OPEN-FIELD" RADIATION ADAPTATION EXPERIMENT AFTER THE CHERNOBYL ACCIDENT AND PROVIDE THE FIRST EVIDENCE OF THE INVOLVEMENT OF EPIGENETIC CHANGES IN ADAPTATION OF A EUKARYOTE-SCOTS PINE (PINUS SILVESTRIS), TO CHRONIC RADIATION EXPOSURE. WE HAVE EVALUATED GLOBAL GENOME METHYLATION OF CONTROL AND RADIATION-EXPOSED PINE TREES USING A METHOD BASED ON CLEAVAGE BY A METHYLATION-SENSITIVE HPAII RESTRICTION ENDONUCLEASE THAT LEAVES A 5' GUANINE OVERHANG AND SUBSEQUENT SINGLE NUCLEOTIDE EXTENSION WITH LABELED [3H] DCTP. WE HAVE FOUND THAT GENOMIC DNA OF EXPOSED PINE TREES WAS CONSIDERABLY HYPERMETHYLATED. MOREOVER, HYPERMETHYLATION APPEARED TO BE DEPENDENT UPON THE RADIATION DOSE ABSORBED BY THE TREES. SUCH HYPERMETHYLATION MAY BE VIEWED AS A DEFENSE STRATEGY OF PLANTS THAT PREVENTS GENOME INSTABILITY AND RESHUFFLING OF THE HEREDITARY MATERIAL, ALLOWING SURVIVAL IN AN EXTREME ENVIRONMENT. FURTHER STUDIES ARE CLEARLY NEEDED TO ANALYZE IN DETAIL THE INVOLVEMENT OF DNA METHYLATION AND OTHER EPIGENETIC MECHANISMS IN THE COMPLEX PROCESS OF RADIATION STRESS AND ADAPTIVE RESPONSE. 2003 15 564 29 BASAL CELL CARCINOMAS OF THE SCALP AFTER RADIOTHERAPY FOR TINEA CAPITIS IN CHILDHOOD: A GENETIC AND EPIGENETIC STUDY WITH COMPARISON WITH BASAL CELL CARCINOMAS EVOLVING IN CHRONICALLY SUN-EXPOSED AREAS. BACKGROUND: BASAL CELL CARCINOMA (BCC) HAS BEEN MOSTLY ASSOCIATED WITH SUN EXPOSURE, BUT IONIZING RADIATION IS ALSO A KNOWN RISK FACTOR. IT IS NOT CLEAR IF THE PATHOGENESIS OF BCC, NAMELY AT A GENOMIC AND EPIGENETIC LEVEL, DIFFERS ACCORDING TO THE UNDERLYING TRIGGERING FACTORS. OBJECTIVE: THE PRESENT STUDY AIMS TO COMPARE GENETIC AND EPIGENETIC CHANGES IN BCCS RELATED TO IONIZING RADIATION AND CHRONIC SUN EXPOSURE. METHODS: TUMOR SAMPLES FROM BCCS OF THE SCALP IN PATIENTS SUBMITTED TO RADIOTHERAPY TO TREAT TINEA CAPITIS IN CHILDHOOD AND BCCS FROM SUN-EXPOSED AREAS WERE ANALYSED THROUGH ARRAY COMPARATIVE GENOMIC HYBRIDIZATION (ARRAY-CGH) AND METHYLATION-SPECIFIC MULTIPLEX LIGATION-DEPENDENT PROBE AMPLIFICATION (MS-MLPA) TO DETECT COPY NUMBER ALTERATIONS AND METHYLATION STATUS OF SPECIFIC GENES. RESULTS: GENOMIC CHARACTERIZATION OF TUMOR SAMPLES REVEALED SEVERAL COPY NUMBER GAINS AND LOSSES IN ALL CHROMOSOMES, WITH THE MOST FREQUENT GAINS OBSERVED AT 2P, 6P, 12P, 14Q, 15Q, 18Q, XP AND YP, AND THE MOST FREQUENT LOSSES OBSERVED AT 3Q, 14Q, 16P, 17Q, 22Q, XP, YP AND YQ. WE DEVELOPED A STATISTICAL MODEL, ENCOMPASSING GAINS IN 3P AND 16P AND LOSSES IN 14Q AND 20P, WITH POTENTIAL TO DISCRIMINATE BCC SAMPLES WITH SPORADIC AETIOLOGY FROM BCC SAMPLES THAT EVOLVE AFTER RADIOTHERAPY IN CHILDHOOD FOR THE TREATMENT OF TINEA CAPITIS, WHICH PRESENTED STATISTICAL SIGNIFICANCE (P = 0.003). FEW METHYLATED GENES WERE DETECTED THROUGH MS-MLPA, MOST FREQUENTLY RARB AND CD44. CONCLUSIONS: OUR STUDY REPRESENTS A STEP FORWARD IN THE UNDERSTANDING OF THE GENETIC MECHANISMS UNDERLYING THE PATHOGENESIS OF BCC AND SUGGESTS POTENTIAL DIFFERENCES ACCORDING TO THE UNDERLYING RIS K FACTORS. 2021 16 1656 28 DOUBLE STRAND BREAKS CAN INITIATE GENE SILENCING AND SIRT1-DEPENDENT ONSET OF DNA METHYLATION IN AN EXOGENOUS PROMOTER CPG ISLAND. CHRONIC EXPOSURE TO INDUCERS OF DNA BASE OXIDATION AND SINGLE AND DOUBLE STRAND BREAKS CONTRIBUTE TO TUMORIGENESIS. IN ADDITION TO THE GENETIC CHANGES CAUSED BY THIS DNA DAMAGE, SUCH TUMORS OFTEN CONTAIN EPIGENETICALLY SILENCED GENES WITH ABERRANT PROMOTER REGION CPG ISLAND DNA HYPERMETHYLATION. WE HEREIN EXPLORE THE RELATIONSHIPS BETWEEN SUCH DNA DAMAGE AND EPIGENETIC GENE SILENCING USING AN EXPERIMENTAL MODEL IN WHICH WE INDUCE A DEFINED DOUBLE STRAND BREAK IN AN EXOGENOUS PROMOTER CONSTRUCT OF THE E-CADHERIN CPG ISLAND, WHICH IS FREQUENTLY ABERRANTLY DNA HYPERMETHYLATED IN EPITHELIAL CANCERS. FOLLOWING THE ONSET OF REPAIR OF THE BREAK, WE OBSERVE RECRUITMENT TO THE SITE OF DAMAGE OF KEY PROTEINS INVOLVED IN ESTABLISHING AND MAINTAINING TRANSCRIPTIONAL REPRESSION, NAMELY SIRT1, EZH2, DNMT1, AND DNMT3B, AND THE APPEARANCE OF THE SILENCING HISTONE MODIFICATIONS, HYPOACETYL H4K16, H3K9ME2 AND ME3, AND H3K27ME3. ALTHOUGH IN MOST CELLS SELECTED AFTER THE BREAK, DNA REPAIR OCCURS FAITHFULLY WITH PRESERVATION OF ACTIVITY OF THE PROMOTER, A SMALL PERCENTAGE OF THE PLATED CELLS DEMONSTRATE INDUCTION OF HERITABLE SILENCING. THE CHROMATIN AROUND THE BREAK SITE IN SUCH A SILENT CLONE IS ENRICHED FOR MOST OF THE ABOVE SILENT CHROMATIN PROTEINS AND HISTONE MARKS, AND THE REGION HARBORS THE APPEARANCE OF INCREASING DNA METHYLATION IN THE CPG ISLAND OF THE PROMOTER. DURING THE ACUTE BREAK, SIRT1 APPEARS TO BE REQUIRED FOR THE TRANSIENT RECRUITMENT OF DNMT3B AND SUBSEQUENT METHYLATION OF THE PROMOTER IN THE SILENT CLONES. TAKEN TOGETHER, OUR DATA SUGGEST THAT NORMAL REPAIR OF A DNA BREAK CAN OCCASIONALLY CAUSE HERITABLE SILENCING OF A CPG ISLAND-CONTAINING PROMOTER BY RECRUITMENT OF PROTEINS INVOLVED IN SILENCING. FURTHERMORE, WITH CONTRIBUTION OF THE STRESS-RELATED PROTEIN SIRT1, THE BREAK CAN LEAD TO THE ONSET OF ABERRANT CPG ISLAND DNA METHYLATION, WHICH IS FREQUENTLY ASSOCIATED WITH TIGHT GENE SILENCING IN CANCER. 2008 17 1399 33 DIET-INDUCED OBESITY MODULATES EPIGENETIC RESPONSES TO IONIZING RADIATION IN MICE. BOTH EXPOSURE TO IONIZING RADIATION AND OBESITY HAVE BEEN ASSOCIATED WITH VARIOUS PATHOLOGIES INCLUDING CANCER. THERE IS A CRUCIAL NEED IN BETTER UNDERSTANDING THE INTERACTIONS BETWEEN IONIZING RADIATION EFFECTS (ESPECIALLY AT LOW DOSES) AND OTHER RISK FACTORS, SUCH AS OBESITY. IN ORDER TO EVALUATE RADIATION RESPONSES IN OBESE ANIMALS, C3H AND C57BL/6J MICE FED A CONTROL NORMAL FAT OR A HIGH FAT (HF) DIET WERE EXPOSED TO FRACTIONATED DOSES OF X-RAYS (0.75 GY X4). BONE MARROW MICRONUCLEUS ASSAYS DID NOT SUGGEST A MODULATION OF RADIATION-INDUCED GENOTOXICITY BY HF DIET. USING MSP, WE OBSERVED THAT THE PROMOTERS OF P16 AND DAPK GENES WERE METHYLATED IN THE LIVERS OF C57BL/6J MICE FED A HF DIET (IRRADIATED AND NON-IRRADIATED); MGMT PROMOTER WAS METHYLATED IN IRRADIATED AND/OR HF DIET-FED MICE. IN ADDITION, METHYLATION PCR ARRAYS IDENTIFIED EP300 AND SOCS1 (WHOSE PROMOTERS EXHIBITED HIGHER METHYLATION LEVELS IN NON-IRRADIATED HF DIET-FED MICE) AS POTENTIAL TARGETS FOR FURTHER STUDIES. WE THEN COMPARED MICRORNA REGULATIONS AFTER RADIATION EXPOSURE IN THE LIVERS OF C57BL/6J MICE FED A NORMAL OR AN HF DIET, USING MICRORNA ARRAYS. INTERESTINGLY, RADIATION-TRIGGERED MICRORNA REGULATIONS OBSERVED IN NORMAL MICE WERE NOT OBSERVED IN OBESE MICE. MIR-466E WAS UPREGULATED IN NON-IRRADIATED OBESE MICE. IN VITRO FREE FATTY ACID (PALMITIC ACID, OLEIC ACID) ADMINISTRATION SENSITIZED AML12 MOUSE LIVER CELLS TO IONIZING RADIATION, BUT THE INHIBITION OF MIR-466E COUNTERACTED THIS RADIO-SENSITIZATION, SUGGESTING THAT THE MODULATION OF RADIATION RESPONSES BY DIET-INDUCED OBESITY MIGHT INVOLVE MIR-466E EXPRESSION. ALL TOGETHER, OUR RESULTS SUGGESTED THE EXISTENCE OF DIETARY EFFECTS ON RADIATION RESPONSES (ESPECIALLY EPIGENETIC REGULATIONS) IN MICE, POSSIBLY IN RELATIONSHIP WITH OBESITY-INDUCED CHRONIC OXIDATIVE STRESS. 2014 18 5463 32 RESIDENTIAL PM(2.5) EXPOSURE AND THE NASAL METHYLOME IN CHILDREN. RATIONALE: PM(2.5-)INDUCED ADVERSE EFFECTS ON RESPIRATORY HEALTH MAY BE DRIVEN BY EPIGENETIC MODIFICATIONS IN AIRWAY CELLS. THE POTENTIAL IMPACT OF EXPOSURE DURATION ON EPIGENETIC ALTERATIONS IN THE AIRWAYS IS NOT YET KNOWN. OBJECTIVES: WE AIMED TO STUDY ASSOCIATIONS OF FINE PARTICULATE MATTER PM(2.5) EXPOSURE WITH DNA METHYLATION IN NASAL CELLS. METHODS: WE CONDUCTED NASAL EPIGENOME-WIDE ASSOCIATION ANALYSES WITHIN 503 CHILDREN FROM PROJECT VIVA (MEAN AGE 12.9 Y), AND EXAMINED VARIOUS EXPOSURE DURATIONS (1-DAY, 1-WEEK, 1-MONTH, 3-MONTHS AND 1-YEAR) PRIOR TO NASAL SAMPLING. WE USED RESIDENTIAL ADDRESSES TO ESTIMATE AVERAGE DAILY PM(2.5) AT 1 KM RESOLUTION. WE COLLECTED NASAL SWABS FROM THE ANTERIOR NARES AND MEASURED DNA METHYLATION (DNAM) USING THE ILLUMINA METHYLATIONEPIC BEADCHIP. WE TESTED 719,075 HIGH QUALITY AUTOSOMAL CPGS USING CPG-BY-CPG AND REGIONAL DNAM ANALYSES CONTROLLING FOR MULTIPLE COMPARISONS, AND ADJUSTED FOR MATERNAL EDUCATION, HOUSEHOLD SMOKERS, CHILD SEX, RACE/ETHNICITY, BMI Z-SCORE, AGE, SEASON AT SAMPLE COLLECTION AND CELL-TYPE HETEROGENEITY. WE FURTHER CORRECTED FOR BIAS AND GENOMIC INFLATION. WE TESTED FOR REPLICATION IN A COHORT FROM THE NETHERLANDS (PIAMA). RESULTS: IN ADJUSTED ANALYSES, WE FOUND 362 CPGS ASSOCIATED WITH 1-YEAR PM(2.5) (FDR < 0.05), 20 CPGS PASSING BONFERRONI CORRECTION (P < 7.0X10(-8)) AND 10 DIFFERENTIALLY METHYLATED REGIONS (DMRS). IN 445 PIAMA PARTICIPANTS (MEAN AGE 16.3 YEARS) 11 OF 203 AVAILABLE CPGS REPLICATED AT P < 0.05. WE OBSERVED DIFFERENTIAL DNAM AT/NEAR GENES IMPLICATED IN CELL CYCLE, IMMUNE AND INFLAMMATORY RESPONSES. THERE WERE NO CPGS OR REGIONS ASSOCIATED WITH PM(2.5) LEVELS AT 1-DAY, 1-WEEK, OR 1-MONTH PRIOR TO SAMPLE COLLECTION, ALTHOUGH 2 CPGS WERE ASSOCIATED WITH PAST 3-MONTH PM(2.5). CONCLUSION: WE OBSERVED WIDE-SPREAD DNAM VARIABILITY ASSOCIATED WITH AVERAGE PAST YEAR PM(2.5) EXPOSURE BUT WE DID NOT DETECT ASSOCIATIONS WITH SHORTER-TERM EXPOSURE. OUR RESULTS SUGGEST THAT NASAL DNAM MARKS REFLECT CHRONIC AIR POLLUTION EXPOSURE. 2021 19 6552 28 TRANSGENERATIONAL DNA METHYLATION CHANGES IN DAPHNIA MAGNA EXPOSED TO CHRONIC GAMMA IRRADIATION. OUR AIM WAS TO INVESTIGATE EPIGENETIC CHANGES IN DAPHNIA MAGNA AFTER A 25-DAY CHRONIC EXTERNAL GAMMA IRRADIATION (GENERATION F0 EXPOSED TO 6.5 MUGY.H(-1) OR 41.3 MGY.H(-1)) AND THEIR POTENTIAL INHERITANCE BY SUBSEQUENT RECOVERING GENERATIONS, NAMELY, F2 (EXPOSED AS GERMLINE CELLS IN F1 EMBRYOS) AND F3 (THE FIRST TRULY UNEXPOSED GENERATION). EFFECTS ON SURVIVAL, GROWTH, AND REPRODUCTION WERE OBSERVED AND DNA WAS EXTRACTED FOR WHOLE-GENOME BISULFITE SEQUENCING IN ALL GENERATIONS. RESULTS SHOWED EFFECTS ON REPRODUCTION IN F0 BUT NO EFFECT IN THE SUBSEQUENT GENERATIONS F1, F2, AND F3. IN CONTRAST, WE OBSERVED SIGNIFICANT METHYLATION CHANGES AT SPECIFIC CPG POSITIONS IN EVERY GENERATION INDEPENDENT OF DOSE RATE, WITH A MAJORITY OF HYPOMETHYLATION. SOME OF THESE CHANGES WERE SHARED BETWEEN DOSE RATES AND BETWEEN GENERATIONS. ASSOCIATED GENE FUNCTIONS INCLUDED GENE FAMILIES AND GENES THAT WERE PREVIOUSLY SHOWN TO PLAY ROLES DURING EXPOSURE TO IONIZING RADIATION. COMMON METHYLATION CHANGES DETECTED BETWEEN GENERATIONS F2 AND F3 CLEARLY SHOWED THAT EPIGENETIC MODIFICATIONS CAN BE TRANSMITTED TO UNEXPOSED GENERATIONS, MOST LIKELY THROUGH THE GERMLINE, WITH POTENTIAL IMPLICATIONS FOR ENVIRONMENTAL RISK. 2018 20 184 22 ACCOUNTING FOR TRANSGENERATIONAL EFFECTS OF TOXICANT EXPOSURE IN POPULATION MODELS ALTERS THE PREDICTED LONG-TERM POPULATION STATUS. ACUTE ENVIRONMENTAL STRESSORS SUCH AS SHORT-TERM EXPOSURE TO POLLUTANTS CAN HAVE LASTING EFFECTS ON ORGANISMS, POTENTIALLY IMPACTING FUTURE GENERATIONS. PARENTAL EXPOSURE TO TOXICANTS CAN RESULT IN CHANGES TO THE EPIGENOME (E.G., DNA METHYLATION) THAT ARE PASSED DOWN TO SUBSEQUENT, UNEXPOSED GENERATIONS. HOWEVER, IT IS DIFFICULT TO GAUGE THE CUMULATIVE POPULATION-SCALE IMPACTS OF EPIGENETIC EFFECTS FROM LABORATORY EXPERIMENTS ALONE. HERE, WE DEVELOPED A SIZE- AND AGE-STRUCTURED DELAY-COORDINATE POPULATION MODEL TO EVALUATE THE LONG-TERM CONSEQUENCES OF EPIGENETIC MODIFICATIONS ON POPULATION SUSTAINABILITY. THE MODEL EMULATED CHANGES IN GROWTH, MORTALITY, AND FECUNDITY IN THE F0, F1, AND F2 GENERATIONS OBSERVED IN EXPERIMENTS IN WHICH LARVAL MENIDIA BERYLLINA WERE EXPOSED TO ENVIRONMENTALLY RELEVANT CONCENTRATIONS OF BIFENTHRIN (BIF), ETHINYLESTRADIOL (EE2), LEVONORGESTREL (LV), OR TRENBOLONE (TB) IN THE PARENT GENERATION (F0) AND REARED IN CLEAN WATER UP TO THE F2 GENERATION. OUR ANALYSIS SUGGESTS POTENTIALLY DRAMATIC POPULATION-LEVEL EFFECTS OF REPEATED, CHRONIC EXPOSURES OF EARLY-LIFE STAGE FISH THAT ARE NOT CAPTURED BY MODELS NOT ACCOUNTING FOR THOSE EFFECTS. SIMULATED EXPOSURES LED TO SUBSTANTIAL DECLINES IN POPULATION ABUNDANCE (LV AND BIF) OR NEAR-EXTINCTION (EE2 AND TB) WITH THE EXACT TRAJECTORY AND TIMELINE OF POPULATION DECLINE DEPENDENT ON THE COMBINATION OF F0, F1, AND F2 EFFECTS PRODUCED BY EACH COMPOUND. EVEN ACUTE ONE-TIME EXPOSURES OF EACH COMPOUND LED TO DECLINES AND RECOVERY OVER MULTIPLE YEARS DUE TO LAGGED EPIGENETIC EFFECTS. THESE RESULTS DEMONSTRATE THE POTENTIAL FOR ENVIRONMENTALLY RELEVANT CONCENTRATIONS OF COMMONLY USED COMPOUNDS TO IMPACT THE POPULATION DYNAMICS AND SUSTAINABILITY OF AN ECOLOGICALLY RELEVANT SPECIES AND MODEL ORGANISM. 2022