Progress 01/01/00 to 12/31/08
Outputs
OUTPUTS: The objective was to investigate the association between male age and the frequency of sperm with de novo structural chromosomal abnormalities . Methods: Semen specimens collected from two groups of 10 healthy, nonsmoking men, aged 22-28 and 65-80 years were analyzed with the use of a multicolor fluorescence in situ hybridization assay for detecting breaks, segmental duplications and deletions, and aneuploidy and diploidy involving chromosome 1. Results: Significant increases in the frequency of sperm carrying breaks and segmental duplications and deletions of chromosome 1 among older men compared with younger men. Older men carried twice the frequency of sperm with segmental duplications and deletion of chromosome 1. The frequency of sperm carrying breaks within the 1q12 fragile-site region nearly doubled in older men. In contrast to female gametes, there was no effect of age on the frequency of sperm with numerical chromosomal abnormalities. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Our findings suggest that advancing male age is associated with a gradual and significant increase in the risk of fathering children with various chromosomal defects such as segmental aneusomy syndromes.
Publications
- John K., Keshava, C., Richardson, D., Weston, A., and Nath, J. 2008. Immune response signatures of benzo(a) pyrene exposure in normal human epithelial cells in the absence or presence of chlorophyllin. Cancer Genomics and Proteomics. Participants: All authors included in publication. Target Audiences: Reproductive biologists including veterinarians and general public.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Semen quality is associated with fertility status, but there is little quantitative information on risk factors that affect semen quality, especially in non-clinical populations. Advancing male age has been associated with a decline in semen quality, with the largest effect being on sperm motility. However, there is little quantitative data on the specific components of sperm motion that are affected by male age. METHODS: We performed linear regression analyses of 14 aspects of semen quality measured by computer-assisted semen analysis (CASA) in a non-clinical cohort of 90 non-smoking men, aged 22-80 years, who had no history of infertility or reproductive problems. RESULTS: We found age-associated declines in CASA-determined motility (% motile, 0.8% per year; % progressively motile, 0.9 % per year; % rapidly motile, 0.4%per year, P <0.001) and three quantitative aspects of sperm motion [linearity (LIN), 0.2% per year; straight line velocity (VSL), 0.2% per year, and average
path velocity (VAP), 0.3% per year, P<0.05], with no evidence for age thresholds and no significant association with abstinence duration. Age was not significantly associated with amplitude of lateral head (ALH) displacement, beat cross frequency (BCF) and nuclear elongation or size. DISSEMINATION OF RESULTS: Results of these investigations have been disseminated via publications in Human Reproduction and Fertility and Sterility (listed below).
PARTICIPANTS: All authors included in publication.
TARGET AUDIENCES: Reproductive biologists including veterinarians' and general public.
Impacts
Quantitative analysis of sperm motion indicates that as men age, they produce fewer motile sperm, which are able to travel less along a linear path thus covering less forward distance per unit time. These findings may have fertility implications for men who choose to delay fatherhood.
Publications
- Sloter, E., Schmid, T., Marchetti, F., Eskenazi, B., Nath, J., and Wyrobek, A. 2006. Quantitative effects of male age on sperm motion. 2006. Human Reproduction. 21:2868-2875.
- Sloter, E., Marchetti, F., Eskenazi, B., Nath, J. , and Wyrobek, A. 2007. Frequency of human sperm carrying structural aberrations of chromosome increases with advancing age. Fertility and Sterility. 87:1077-1086.
- John, K., Keshava, C., Richardson, D., Weston, A., and Nath, J. 2007. Gene expression in normal human mammary epithelial cells (NHMEC) exposed to Benzo (a) pyrene (BP) in the presence and absence of chlorophyllin Environmental and Molecular Mutagenesis. 48:597.
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Progress 01/01/06 to 12/31/06
Outputs
The objective of this study was to review evidence regarding the effects of male age on germinal and heritable chromosomal abnormalities using available human and rodent studies and to evaluate possible underlying mechanisms. There was little evidence from offspring or germ cell studies for a generalized male age effect on autosomal aneuploidy, except in rodents. Sex chromsomal nondisjunction increased with age in both human and rodent male germ cells. Both human and rodent data showed age-related increases in the number of sperm with chromosomal breaks and fragments and suggest that postmeiotic cells are particularly vulnerable to the effects of aging. Translocation frequencies increased with age in murine spermatocytes, at rates comparable to mouse and human somatic cells. Age-related mechanisms of induction may include accumulation of environmental damage, reduced efficiency of DNA repair, increased genomic instability, genetic factors, hormonal influences,
suppressed apoptosis, or decreased effectiveness of antioxidants and micronutrients.
Impacts
The weight of evidence suggests that the increasing trend toward fathering at older ages may have significant effects on the viability and genetic health of human pregnancies and offspring, primarily as a result of structural chromosomal aberrations in sperm.
Publications
- Ghanem, M., Batelli, L., Mercer, R., Seabilloni, J., Kashon, M., Ma, J., Nath, J., and Hubbs, A. 2006. Apaptosis and Bax expression are increased by coal dust in the polycyclic aromatic hydrocarbon-exposed-lung. Environmental Health Perspectives 114:1367-1373.
- White, J., Becker, R., Mclean, I., Director-Myska, A., and Nath, J. 2006. Molecular cytogenetic evaluation of 10 uveal melanoma cell lines. Cancer Genetics and Cytogenetics. 168:11-21.
- White, J., Mclean, I., Becker, R., Director-Myska, A., and Nath, J. 2006. Correlation of comparative genomie hybridization results of 100 archival uveal melanomas with patient survival. Cancer Genetics and Cytogenetics. 170: 29-39.
- John, K., Divi, R., Keshava, C., Whipkey, D., Poirier, M., Orozco, C., Shockley, M., Weston, M., and Nath, J. 2006. Modulation by chlorophyllin of benzo(a)pyrene (BP) dependent CYP1 induction and DNA adduct formation in normal mammary cells (NHMECs) and MCF cells. Environmental and Molecular Mutagenesis. 47:426.
- John, K., Keshava, C., Whipkey, D., Poirier, M., Weston, A., and Nath, J. 2006. Chlorophyllin differentially modulates CYP1 gene expression in normal human mammary epichelial cells (NHMECs) exposed to benzopyranes. American Assoc. for Cancer Research Page 357.
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Progress 01/01/05 to 12/31/05
Outputs
There was little evidence from offspring or germ cell studies for a generalized male age effect on autosomal aneuploidy, except in rodents. Sex chromosomal nondisjunction increased with age in both human and rodent male germ cells. Both human and rodent data showed age-related increases in the number of sperm with chromosomal breaks and fragments and suggest that postmeiotic cells are particularly vulnerable to the effects of aging. Translocation frequencies increased with age in murine spermatocytes, at rates comparable to mouse and human somatic cells. Age-related mechanisms of induction may include accumulation of environmental damage, reduced efficiency of DNA repair, increased genomic instability, genetic factors, hormonal influences, suppressed apoptosis, or decreased effectiveness of antioxidants and micronutrients.
Impacts
The weight of evidence suggests that the increasing trend toward fathering at older ages may have significant effects on the viability and genetic health of human pregnancies and offspring, primarily as a result of structural chromosomal aberrations in sperm.
Publications
- Wyrobek, A., Eskenazi, B., Evenson, D., Arnheim, N., Marchetti, F., Nath, J., Young, S., Sloter, E., Pearson, F., Tiemann-Boege, Il, Kidd, S., Moore, L., and Moore II, D. 2005. Advancing age among healthy non-smoking males is associated with reduced sperm motility and increased frequencies of sperm with DNA fragmentation chromosomal abnormalities and gene mutations. (Abstract) 9th International Conference on Environmental Mutagens, San Francisco, CA. Pg. 132.
- Ghanem, M., Salem., M., Yao, J., Rexroad, C., and Nath, J. 2005. Modifications of induced Cytochorme P450 1A1 in rainbow trout by polychlorinated biophenyls (PCB) on fish diet. (Abstract) International Conference on Environmental Mutagens, San Francisco, CA. Pg. 164.
- John, K., Divi, R., Keshava, C., Orozco, C., Whipkey, D., Poirier, M., Nath, J., and Weston, A. 2005. Gene expression and DNA adduct formation is modulated by chlorophyllin in normal human mammary epithelial cells exposed to benzene (a) pyrene (BP). (Abstract) International Conference on Environmental Mutagens, San Francisco, CA. Pg. 170.
- John, Kaarthik, Divi., Keshava, C., Orozco, C., Whipkey, D., Poirier, M., Weston, A., and Nath, J. 2005. Chlorophyllin modulates gene expression and DNA-adduct formation in normal human mammary epithetial cells exposed to benzo (a) pyrene (BP). Annual Association for Cancer ResearchMeeting. Anaheim, CA.
- Salem, M., Yao, J, Rexroad, C., Kenny, B., Semmens, K., Killefer, J., and Nath, J. 2005. Fish calapastatin gene structure: a putative role in monitoring muscle growth and quality. The United States Aquaculture Society Meeting, Aquaculture America, New Orleans.
- Salem, M., Kenney, B., Killefer, J. and Nath, J. 2005. Isolation and characterization of calpains from rainbow trout muscle and their role in texture development. J. of Muscle Science. 15:245-255.
- Salem, M., Nath, J., Caird, R., Killefer, J., and Yao, J. 2005. Identification and molecular characterization of the rainbow trout calpains: their expression in muscle wasting during starvation. Comparative Biochemistry and Physiology. 140:63-71.
- Salem, M., Yao, J., Rexroad, C., Kenney, B., Semmens, K., Killefer, J., and Nath, J. 2005. Characterization of calpastatin gene in fish: Its potential role in muscle growth and fillet quality. Comparative Biochemistry and Physiology 141:488-497
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Progress 01/01/04 to 12/31/04
Outputs
Cytochrome P4501A1 (CYP1A1) metabolizes polycyclic aromatic hydrocarbons in cigarette smoke to DNA-binding reactive intermediates associated with carcinogenesis. Epidemiologic studies indicate that the majority of coal miners are smokers but have a lower risk of lung cancer than other smokers. We hypothesized that coal dust (CD) exposure modifies pulmonary carcinogenesis by altering CYP1A1 induction. Therefore, male Sprague Dawley rats were intratracheally instilled with 2.5, 10, 20, or 40 mg CD/rat or vehicle (saline); and 11 d later, pulmonary CYP1A1 was induced by intraperitoneal injection of B-naphthoflavone (BNF; 50 mg/kg). Fourteen days after CD exposure, CYP1A1 protein and activity were measured by Western blot and 7-ethoxyresorufin-O-deethylase activity, respectively. CYP1A1 and the alveolar type II markers, cytokeratins 8/18, were localized and quantified in lung sections by dual immunofluorescence with morphometry. The area of CYP1A1 expression in alveolar
septa and alveolar type II cells in response to BNF was reduced by exposure to 20 or 40 mg CD compared with BNF-induced 7-ethoxyresorufin-O-deethylase activity in a dose-responsive manner. By Western blot, induction of CYP1A1 protein by BNF was significantly reduced by 40 mg CD compared with BNF alone. These findings indicate that CD decreases BNF-induced CYP1A1 protein expression and activity in the lung.
Impacts
Because increased pulmonary CYP1A1 activity is associated with increased benzo [a] pyrene DNA adducts and risk of lung cancer from cigarette smoking, alterations in CYP1A1 from exposures in coal mining could affect the lung cancer risk. Our studies on rat lungs showed that not only was CYP1A1 induction modified by coal dust exposure, but the activity of another CYP isoform, CYP2BI, was suppressed in a dose-dependent fashion. Overall coal dust exposure has the ability to trigger pulmonary inflammation.
Publications
- Tomascik-Cheeseman, L., Coleman, M., Marchetti, F., Nelson, D., Kegelmeyer, L., Nath, J. and Wyrobek, A. Differential basal expression of genes associated with stress response, damage control and DNA repair among mouse tissues. Mutation Research. 561: 1-14. 2004
- Salem, M., Killefer, J., Yao, J., and Nath, J. Identification and characterization of rainbow trout calpain catalytic subunits (Capn 1 and Capn 2) during starvation. (abstract) FASEB J. C138. 2004.
- Ghanem, M., Hubbs, A., Kashon, M., Weisman, D., Porter D., Batelli, L., Vallayathan, V., and Nath, J. Cytochrome P4501A1 (CYP1A1) induction is suppressed by coal dust exposure in the ovine lung. (abstract). Environmental and Molecular Mutagenesis 44(3):200. 2004
- John, K., Keshava, C., Divi, R., Whipkey, D., Poirer, M., Weston, A., and Nath, J. Modulation of CYP1A1 expression by chlorophyllin in normal human mammary epithelial cells exposed to benzo [a] pyrene. (Abstract). Environmental and Molecular Mutagenesis. 44(3); 208. 2004
- Salem, M., Semmens, K., Tierney, A., Viadero, R., and Nath, J. Using the treated acid mine water for the rainbow trout production at Dogwood lake in West Virginia. (Abstract). Environmental and Molecular Mutagenesis. 44(3);233. 2004
- Salem, M., Kenny, P., Killefer, J., and Nath, J. Isolation and in vitro characterization of the Calpains from rainbow trout (Oncorhynchus Mykiss) muscle and their role in texture development. (Abstract). Experimental Biology. A 100. 2004
- Ghanem, M., Porter, D., Batelli, R., Vallayathan, V., Kashon, M., Ma, Jane., Barger, M., Nath, J. Castranova, V., and Hubbs, A. Respirable coal dust particles modify cytochrome P4501A1. (CYP1A1) expression in rat alveolar cells. AM. J. Respir. Cell Mol. Biol 31:171-183. 2004
- Sloter, S., Nath, J., Eskanazi, B., and Wyrobek, A. Effects of male age on the frequencies of germinal and heritable chromosomal abnormalities in humans and rodents. Fertility and Sterility. 81(4) 925-943. 2004
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Progress 01/01/03 to 12/31/03
Outputs
The third isoform of metallothionein (MT-3) is over-expressed in some breast cancers and its expression is associated with a poor disease outcome. In the PC-3 prostate cancer cell line, MT-3 expression has been shown to inhibit cell growth and increase drug resistance. The goal of the present study was to determine if MT-3 over-expression would influence the growth of human breast cancer cell lines. To determine this, the coding sequence of the MT-3 gene was stably transfected into two estrogen positive (MCF-7 and T-47D) and two estrogen receptor negative cell lines (Hs578Tand MDA-MB-231) having no basal expression of MT-3. Cell growth was determined by counting DAPI-stained nuclei, cadmium resistance by the colony formation assay, MT mRNA expression by RT-PCR, and MT protein by immuno-blot. It was demonstrated that MCF-7 and Hs578T cells that over-express the MT-3 gene were growth inhibited compared to untransfected cells. In contrast, T-47D and MDA-MB-231 cells that
overexpress MT-3 were not inhibited. Stable transfection of the MT-1E gene had no effect on the growth of any of the four cell lines. It was also demonstrated that the over-expression of both MT-3 and MT-1E only increased the resistance of MCF-7 cells to Cd+2. In all instances, stable transfection of the MT-3 or MT-1E gene had no effect on the expression of the other MT isoforms. The study shows that MT-3 can influence the growth of some breast cancer cell lines.
Impacts
The effects MT-3 on both cell growth and its role as a potential marker for breast cancer prognosis appear to be unique properties that are distinct from the MT-1 and MT-2 members of this gene family. The effect on cell growth is confined to the MT-3 isoform as evidenced by the fact that MT-1E has no effect in both prostate or breast cancer cell lines. Evidence that MT-3 might have a role in predicting tumor prognosis also appears specific for the MT-3 isoform.
Publications
- Rossi, M., Somji, S., Garrett, S., Sens, M., Nath, J., and Sens, D. Expression of hsp60, hsp70, and hsp stress response genes in cultured human urothelial cells (UROtsa) exposed to lethal and sublethal concentrations of sodium arsenite. Environmental Health Perspectives 110:1225-1232. 2002.
- Gurel, V., Sens, D., Somji, S., Garrett, S., Nath, J., and Sens, M. Stable transfection and over-expression of metallothinein isoform 3 inhibits the growth of MCF-7 and Hs578T cells but not that of T-47D or MDA-MB-231 cells. Breast Cancer Research and Treatment. 8:181-191. 2003
- Ghanem, M., Battelli, L., Kashon, M., Ma, Y., Vallayathan, V., Nath, J., and Hubbs, A. Suppression of rabbit pulmonary CYPIAI by intratrachacheal exposure to silica. (abstract). Environmental and Moleular Mutagenesis. 41:175. 2003.
- Salem, M., Killefer, J., and Nath, J. Effect of temperature acclimation on the white muscle gene expression profile of rainbow trout: ESTS and macro-array gene filter approach. (abstract). Environmental and Molecular Mutagenesis 41:202. 2003.
- Ghanem, M., Porter, D., Battelli, L., Kashon, M., Barger, M., Ma, J., Vallayathan, V., Nath, J. and Hubbs, A. Rat pulmonary CYPIAI induction is inhibited by respirable coal dust exposure. (abstract). The Toxicologist. 72:320-321. 2003.
- Salem, M., Killefer, J., and Nath, J. Calpain regulatroy subunit (Capn4) from rainbow trout reveals a novel domain V. Phylogenetic tree for Capn 4 gene superfamily. (abstract). The FASEB Jl. 17:1005. 2003
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Progress 01/01/02 to 12/31/02
Outputs
Exposure to jet fuel damages DNA and results in a number of physiological changes in liver, lung, immune, and neurological tissue. In this study the single-cell gel electrophoresis assay or comet assay was used to compare the DNA damage in human peripheral lymphocytes produced by three jet propulsion fuels: JP-8, JP-5 and JP-8+ 100. These fuels consist of complex mixtures of aliphatic, aromatic, and substituted naphthalene hydrocarbons. Two exposure times were investigated which correspond to estimated occupational exposure times and concentrations of fuels were used that were based on previous fuel toxicity studies. Analysis of samples for the extent of DNA damage as determined by tail moment and percent tail DNA was performed on exposed cells following a brief recovery time. All fuels produced significant increases in DNA damage; however, only JP-8+100 was genotoxic at the lowest exposure concentration. (1:500). At the highest exposure JP-8 and JP9+100 (32.041 +
2.599 and 45.774 + 4.743, respectively) were significantly greater than for JP-5 (1.314 + 0.474). These results indicate that JP-8+100 and JP-8 are capable of damaging lymphocyte DNA to a greater extent than JP-5.
Impacts
Based on comet measures, the JP-8, JP-5, and JP-8+100 jet fuels differ in their relative genotoxicity. The more complex formulations of JP-8 and JP-8+100 are more genotoxic than the simpler JP-5 fuel. This knowledge should prove useful for individuals who work with and are exposed to jet fuels at airports and defense installations..
Publications
- Cheeseman, L., Lowe, X., Marchetti, F., Shamanski, F., Nath, J., Pederson, R. and Wyrobek, A. 2002. Cenp-B is not critical for meiotic chromosome segregation in male mice. 513:197-203.2002.
- Jackman, S., Grant, G., Kolanko, C., Stenger, D. and Nath, J. 2002. DNA damage assessment by Comet assay of human lymphocytes exposed to jet propulsion fuels. Environmental and Molecular Mutagenesis. 40:18-23. 2002.
- Sloter, E., Eseknazi, B., Nath, J., Moore, D., Kidd, S. and Wyrobek, A. 2002. Semen quality and chromosomal integrity of sperm decreases with age among healthy men.(abstract). Environmental and Molecular Mutagenesis. 39:59. 2002
- Tomascik-Cheeseman, L., Marchetti, F., Coleman, M., Yin, E., Nath, J. and Wyrobek, A. 2002. Stage-dependent transcriptional profiling of male germ cells. (abstract). 39:63. 2002.
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Progress 01/01/01 to 12/31/01
Outputs
As the measurement of chromosomal translocations increases in popularity for quantifying prior radiation exposure, information on the possible decline of these "stable" aberrations over time is urgently needed. We report here information about the persistence of radiation-induced chromosome aberrations in vivo over the life span of a rodent. Female C57BL/6 mice were given a single whole-body acute exposure of 0, 1, 2, 3 or 4 Gy 137 Cs ? rays at 8 weeks of age. Chromosome aberrations were analyzed from peripheral blood samples at various intervals between 1 day and 21 months after exposure. Aberrations were detected by painting chromosomes 2 and 8. Translocations decreased dramatically during the first 3 months after irradiation, beyond which time the frequencies remained relatively constant out to 1 year, when the effects of aging and clonal expansion became significant. Both reciprocal and nonreciprocal translocations increased with age in the unexposed control
animals and were involved in clones. As expected of unstable aberrations, dicentrics decreased rapidly after exposure and reached baseline levels within 3 months. These results indicate that the persistence of translocations induced by ionizing radiation is complicated by aging and clonal expansion and that these factors must be considered when quantifying translocations at long times after exposure. These results have implications for biological dosimetry in human populations.
Impacts
By recognizing the loss of translocations over time and the important role of clonal expansion and aging, retrospective closimetry in humans may be substantially improved.
Publications
- Rossi, M., Masters, J., Park, S., Todd, J., Garrett, S. Sens, M., Somji, S., Nath, J. and Sens, D. 2001 The Immortalized URotsa Cell Line as a Potential Cell Culture Model of Human Urothelium. Environ. Health Perspectives. 109: 801-806.
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Progress 01/01/00 to 12/31/00
Outputs
Our previous study showed that both 1-nitropyrene (1-NP) and dibenzo (a, i) pyrene (DBP) induced enhanced growth variants (EGVs) in primary cultures of rat tracheal epithelial (RTE) cells exposed in vivo. Cell lines were established from some of the EGVs. Further studies, using anchorage-independent growth in soft agar and tumorigenicity in athymic nude mice, were performed to determine the neoplastic potenial of EGVs induced by 1-NP and DBP. Results show that three of five from DBP- and five of five from 1-NP-induced cell lines displayed anchorage-independent growth. The colony forming efficiency (CFE) from DBP-induced cell lines was 0.067% and CFE from 1-NP-induced cell lines was 0.151%. There is a significant difference between the two CFEs (X2 =12.08, P < 0.01). Two of five DBP-and five of five 1-NP-induced cell lines produced squamous cell carcinomas (SCC) in nude mice. The rate of tumorigenicity counted by injected sites was 20% (6/30) for DBP-induced cell lines
and 57% (17/30) for 1-NP-induced cell lines. There is a significant difference between the results of tumorigenicity from the cell lines induced by the two different compounds (X2=8.53, P < 0.01). Neither of the two cell lines from spontaneously developed foci grew in soft agar or produced SCC in nude mice. It seems that the neoplastic potential of transformed RTE cells induced by 1-NP was higher than that of DBP.
Impacts
Cell lines induced by 1-N possess stronger neoplastic potential than those induced by DBP. This conclusion may prove important in our understanding of mechanisms related to lung cancer.
Publications
- Nath, J., and Johnson, K. 2000. Fluorescence In situ Hybridization (FISH): Current Status and Future Prospects. Biotechnic and Histochem. 75:54-78.
- Sloter, E., Lowe, X., Moore, D., Nath, J. and Wyrobek, J. 2000. Multicellular FISH Analysis of chromosomal Breaks, Duplications, Deletions, and Numerical Abnormalities in Sperm of Healthy Men. Amer. J. Human Gen. 67:862-872.
- Spruill, M., Nelson, D., Ramsey, M., Nath, J. and Tucker, J. 2000. Lifetime Persistence and Clonality of Chromosome Aberrations in the Peripheral Blood of Mice Acutely Exposed to Ionizing Radiation. Radiation Research. 153:110-121.
- Kolanko, C., Pyle, M., Nath, J., Prasana, P., Loats, H. and Blakely, W. 2000. Color Pigment Immunostaining Based Detection of a PCR-Synthesized Human Pancentromeric DNA Hybridization Probe: Potential for Dicentric Assay Automation. Biotechnic and Histochemistry. 75:91-98.
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Progress 01/01/99 to 12/31/99
Outputs
To investigate whether radiation-induced misrejoining of chromosome breakpoints is randomly or non-randomly distributed throughout the human genome, data were combined from as many published cytogenetic studies as possible. The percentage of radiation-induced breaks per megabase (Mb)of DNA between all human chromosomes was calculated, and the observed and expected numbers of breakpoints based on DNA content between and within chromosomes were compared. A DNA-proportional distribution of breakpoints in 14 autosomes and a statistically significant deviation from proportionality in another eight autosomes and the sex chromosomes was found. Regression analysis showed no significant change in breakpoint frequency per Mb of DNA relative to autosome size. Analysis between chromosome arms showed a non-random distribution of induced breakpoints within certain autosomes, particularly the acrocentrics. In cases of non-random distributions, a prevalence of events was found at
heterochromatic regions and/or telomeres, and a clustering of breakpoints was found near the centromeres of many chromosomes. There is an approximately linear proportionality between autosomal DNA content and observed breakpoint number, suggesting that subsets of autosomes can be used to estimate accurately the overall genomic frequency of misrejoined breakpoints contingent upon a carefully selected subset. However, this conclusion may not apply to the sex chromosomes. The results also support the influence of chromatin organization and/or preferential DNA repair/misrejoining on the distribution of induced breakpoints.
Impacts
Subsets of human autosomes can be used to estimate the genomic frequency of misrejoined breakpoints. These estimates are valuable tools in biodosimetry.
Publications
- Johnson, K., Nath, J., Brenner, D., Geard, C. and Tucker, J. 1999. Chromosome Aberrations of Clonal Origin in Irradiated and Unexposed Individuals: Assessment and Implications. Radiation Research 152:1-5.
- Tucker, J.D. , Spruill, M.D., Ramsey, M.J., Director, A.D. and Nath, J. 1999. Frequency of Spontaneous Chromosome Aberrations in Mice: Effects of Age. Mutation Research. 425:135-141.
- Kolanko, C., Pyle, M., Loats, H., Parton, J., Blakely,W. and Nath, J. 1999. Fast In Situ Hybridization of a Mouse Genomic DNA Probe and Immunoenzmatic Color Pigment Detection of Mouse Bone Marrow Micronucleus. Biotechnic and Histochemistry. 74:111-125.
- Johnson, K., Brenner, D., Nath, J., Geard, R. 1999. Radiation-Induced Breakpoint Misrejoicing in Human Chromosomes: Random or Non-Random? International J. Radiation Biol. 75:131-141.
- Tepperberg, J., Moses, M. and Nath, J. 1999. Colchicine Effects on Meiosis in the Male Mouse. II. Inhibition of Synapsis and Induction of Nondisjunction. Mutation Research. 429:93-105.
- Ensell, M-X., Hubbs, A., Zhou, G., Batelli, L., Nath, J. and Ong. T. 1999. Neoplastic Potential of Rat Tracheal Epithelial Cell Lines Induced by 1-Nitropyrene and Dibenzo (a,i) pyrene. Mutation Research. 444:1930-199.
- Johnson, K., Nath, J., Pluth, J. and Tucker, J. 1999. The Distribution of Chromosome Damage, Nonreciprocal Translocations and Clonal Aberrations in Lymphocytes from Chernobyl Clean-up Workers. Mutation Research. 439:77-85.
- Qian, H.W., Whong, W-Z., Olsen, L., Nath, J. and Ong, T. 1999. Induction of Micronuclei in V79 Cells by Fractions of Roofing Asphalt Fume Condensate. Mutation Research. 441:163-170.
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Progress 01/01/98 to 12/31/98
Outputs
Many workers in the highway construction and roofing industries are potentially exposed to asphalt fumes. However, little is known regarding the carcinogenic hazards of these fumes to the exposed workers. Previous studies have shown that condensates of asphalt fumes are weakly mutagenic to bacteria and are capable of inducing micro-nucleus formation in cultured mammalian cells. In this study, the induction of DNA adducts in vivo in lung and white blood cells (WBCs) of rats by fume condensates of type I and type III roofing asphalts was investigated using 32 P-postlabeling analysis. Male CD rats (3/group) received 3 intratracheal instillations of fume condensates in a 24-h period. DNA from both lung cells and WBCs were isolated and used to detect DNA adducts. Condensates of both roofing asphalt fumes caused DNA adduct fomation in rat lung cells in a similar dose-related manner. Under the conditions studied, however, neither type I nor type III fume condensate induced
DNA adducts in WBCs. These results indicate that 1)condensates of fumes from both type I and type III have similar genotoxic activity, 2)chemicals in the condensations of roofing asphalt fumes can covalently bind to the DNA of rat lung cells, and 3)WBCs may not be a suitable surrogate for lung cells in DNA adduct studies of workers exposed to roofing asphalt fumes.
Impacts
(N/A)
Publications
- Keshava, C., Keshava, N., Ong, T. and Nath, J. 1998. Protective effect of vanillin on radiation-induced micronuclei and chromosomal aberrations V-79 cells. Mutation Research 387:149-159.
- Qian, H., Ong, T., Nath, J. and Whong, W. 1998. Induction of DNA adducts in vivo in rat lung cells by fume condensates of roofing asphalt. Teratogenesis, Carcinogenesis and Mutagenesis. 18:131-140.
- Johnson, K., Tucker, J. and Nath, J. 1998. Frequency distribution and clonality of chromosome damage in human lymphocytes by multicolor FISH. Mutagnesis. 13:217-227.
- Ensell, M., Whong, W., Heng, Z., Nath, J. and Ong, T. 1998. In vitro and in vivo transformation in rat trachael epithelial cells exposed to diesel emission particles and related compounds. Mutation Research. 412:283-291.
- Nath, J. and Johnson, K. 1998. Fluorescence in situ hybridization (FISH): DNA probe production and hybridization criteria. Biotechnic and Histochemistry. 73:06-22.
- Keshava, C., Keshava, N., Whong, Z., Nath, J. and Ong, T. 1998. Inhibition of methatrexate-induced chromosomal damage by vanillin and chlorophyllin in V79 cells. Teratogenesis, Carcinogenesis and Mutagenesis. 17:313-326.
- Director, A., Tucker, J., Ramsey, M. and Nath, J. 1998. Chronic ingestion of clastogen by mice and the frequency of chromosome aberrations. Environmental and Molecular Mutagenesis. 32:139-147.
- Kekshava,N., Keshava, C., Whong, W., Hubbs, A., Nath, J. and Ong, T. 1998. Preneoplastic potential of morphologically distinct transformed foci induced by 3-methylcholanthrine. 32:369-376.
- Nath, J. and Krishna, C. 1998. Safety Screening of Drugs in Cancer Therapy. In Abraham et al. (Eds.) ActaHaematol. 99.138-147.
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Progress 01/01/97 to 12/31/97
Outputs
Environmental exposure to mutagens is believed to play a significant role in human carcinogenesis. Because humans are exposed to a variety of mutagens both in their diet and in the rest of their environment, determination of the in vivo effects of a single mutagen is best done in laboratory animals. In this study, C57BL/6N female mice were used to analyze the effect on chromosomes of chronic ingestion of a mutagen dissolved in drinking water. Cycloposphamide (CP) and urethane (ethyl carbamate, EC) were dissolved in sterile drinking water at concentrations of 0. 32, 64 or 96 ppm and 0, 5,000, 10,000 or 15,000 ppm, respectively. All exposures began at 8 weeks of age and continued through the twentieth week unless terminated earlier due to toxicity. Body weights and water consumption were monitored weekly. Blood and bone marrow were taken from appproximately 5 mice per exposure group at 4, 8 and 12 weeks from the start of exposure. To determine if induced aberrations
persisted, all mice remaining after 12 weeks received drinking water without any carcinogen for an additional 6 weeks. Chromosome translocations measured by painting were not induced in blood or bone marrow cells at any time point for either chemical. However, both carcinogens induced significant increases in micronucleated normochromatic erythrocytes, indicating that the carcinogens reached the tissues examined in these experiments. These results indicate that chronic exposure of mice to chemical carcinogens induces chromosome breakage measurable by micronuclei. However, the breakage and reunion necessary to see chromosome exchanges such as translocations were not observed, at least at the level of sensitivity afforded by this study.
Impacts
(N/A)
Publications
- TEPPERBERG, J., MOSES, M. AND NATH, J. 1997 Colchicine effects on meiosis in the male mouse I Meiotic prophase: synaptic arrest, univalents, loss of damaged spermatocytes and a possile checkpoint at pachkytene. Chromosoma 106:183-192.
- HANDO, J., TUCKER, J., TEPPERBERG, J. AND NATH, J. 1997 X chromosome inactivation and micronuclei in normal and Turner individuals. Human Genetics 100:624-628.
- DIRECTOR, A., RAMSEY, M., TUCKER, J. AND NATH, J. 1997 Cytogenetic studies of mice chronically fed carcinogens. Environmental and Molecular Mutagenesis 29:12.
- NATH, J. AND KRISHNA, G. 1997 Models for safety screening of drugs used in cancer therapy. Fundamental and Molecular Mechanisms of Mutagenesis 549.
- NATH, J. AND KRISHNA, G. 1997 Fundamental and Applied Genetic Toxicology. In: Craig B. and Stitzel, S. (eds. Modern Pharmacology. Little Brown and Company, New York. 69-78.
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Progress 01/01/96 to 12/30/96
Outputs
Folinic acid (FA), clinically called leucovorin, has been widely used as a nutrient supplement in dietary intake and is capable of inhibiting cytotoxicity and chromosomal damage induced by chemicals. However, data on its antigenotoxic effect on radiation-induced chromosomal damage are limited. Exponentially growing V79 Chinese hamster lung cells were exposed to five doses of X-rays (1-12 Gy) and UV radiation (50-800 ug J X 10 2/cm2) and post-treated with 5 or 50 ug FA/ml of culture medium for 16 H. The results showed that X-ray treatment alone produced dose-related clastogenicity as measured by nuclear division index (NDI) and mitotic index (MI). X-rays produced a clear dose-related clastogenicity as measured by percent of micronucleated binucleated cells (MNBN) (5-79%) and percent of aberrant cells (11-92%). FA at 5 ug/ml slightly decreased X-ray induced chromosomal damage in both assays; however, the inhibition was significant (12-46% of MNBN, 14-48% in aberrant
cells) only when X-ray-treated cultures were post-treated with 50 ug FA/ml. Post-treatment of FA had no effect on X-ray induced cytoxicity as measured by NDI and MI. A similar dose-related increase in % MNBN (0.5-10.3%) and percent aberrant cells (6-35%) was produced by UV radiation treatment alone. There were significant percentages of MNBN and aberrant cell inhibitions at both 5 and 50 ug/ml in both assays. These data demonstrate the beneficial effect of FA in decreasing radiation-induced chromosomal damage.
Impacts
(N/A)
Publications
- KESHAVA, C., NAGALAKSHMI, R., ONG. T. & NATH, J. 1996. Inhibitory effects of folinic acid on radiation-induced micronuclei and chromosomal aberrations. Mutation Research 352:123-134.
- HENG, Z., ONG. T. & NATH, J. 1996. In vitro studies on the genotoxicity of 2, 4-dichloro-6-nitrophenol ammonium (DCNPA) and its major metabolite. Mutation Research 368:149-155.
- HENG, Z., NATH J. & ONG. T. 1996. Induction of chromosomal aberrations by 2, 4-dichloro-6-aminophenol in cultured V79 cells. Teratogenesis, Carcinogenesis and Mutagenesis 16:81-87.
- SPRUILL, M., NATH, J & HANDO, J. 1996. The persistence of aberrations in mice induced by gamma radiation as measured by chromosome painting. Mutation Research356:135-145.
- TUCKER, J., NATH, J. & HANDO, J. 1996. Activation status of the X chromosome in human micronucleated lymphocytes. Human Genetics 94:471-475.
- DIRECTOR, A., NATH, J. & TUCKER, J. 1996. Cytogenetic analysis of mice chronically fed the food mutagen 2-amino-1-methyl-6-phenylimidazo (4,5b) pyridine, Mutation Research 359:53-61.
- NATH, C., NATH, J. & GULATI, S. 1996. The role of GM-CSF factors in chronic infections. In: Abraham, et al., (eds.). Molecular Biology of Hematopoiesis, Plenum Press, N.Y. PP. 559-563.
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Progress 10/01/95 to 12/30/95
Outputs
Induction of micronuclie (MN) and structural chromosomal aberrations (SCA) by physical agents such as X-rays and UV radiation has been studied extensively in a variety of cell lines for genotoxicity assessment. However, comparative data on the relationship between these two cytogenetic endpoints are limited. This study compares SCA and MN formation in V79 Chinese hamster lung cells treated with X-rays and UV radiation. Four replicate cultures of exponentially growing cells were exposed to four doses of X-rays (100-800 rads). For two replicate cultures, cytochalasin B (3 #g/ml) was added and cells were harvested 16 h later for MN and nuclear division index (NDI)assessment. For the remaining two replicate cultures, colcemid (0.025 #g/ml) was added 16 h post-treatment and cells were harvested 2 h later for SCA and mitotic index (MI) analyses. This experiment was duplicated using four doses of UV radiation (100-800 #Jx10#/cm#). In the X-ray experiment, generally, a decrease
in the NDI and MI was noted with increasing dose. Also, there was a clear dose-related increase in percent micronucleated binucleated (MNBN) and aberrant cells. A similar dose response, but with lower frequencies, was observed in the UV radiation treatment. These data suggest a good correlation between chromosome damage as measured by percent MNBN and aberrant cells and cytotoxicity as measured by NDI and MI.
Impacts
(N/A)
Publications
- DIRECTOR, A., NATH, J. ET AL. 1995. The cytogentic analysis of mice chronically fed PhIP. 26th Ann. Mtg. Env. Mut. Soc., St. Louis, MO. Env. and Molecular Mutagenesis 25:12.
- HENG, Z., ONG, T. AND NATH, J. 1995. Studies on the clastogenicity of 2, 4-dichloro-6-nitrophenol ammonium in cultured mammalian cells. 26th Ann. Mtg. Env. Mut. Soc., St. Louis, MO. Env. and Molecular Mutagenesis 25:23.
- KESHAVA, C., ONG, T. AND NATH, J. 1995. Comparative studies on radiation-induced micronuclei & chromosomal aberrations in V79 cells. Mut. Research 328:63-71.
- KESHAVA, C., ONG, T. AND NATH, J. 1995. Effect of folinic acid on X-ray induced micronuclei and chromosomal aberrations in V79 cells. 26th Ann. Mtg. Env. Mut. Soc., St. Louis, MO. Env. and Molecular Mutagenesis 25:26.
- SPRUILL, M., RAMSEY, M., SWIGER, J. & NATH, J. 1995. The analysis of stable radiation-induced translocations in mice using chromosome painting. 26th Ann. Mtg. Env. Mut. Soc., St. Louis, MO. Env. and Molecular Mutagenesis 25:50.
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