DNA methylation of GDF-9 and GHR genes as epigenetic regulator of milk production in Egyptian Zaraibi goat.

BACKGROUND: DNA methylation is an epigenetic mechanism that takes place at gene promoters and a potent epigenetic marker to regulate gene expression. OBJECTIVE: The study aimed to improve the milk production of Zaraibi goats by addressing the methylation pattern of two milk production-related genes: the growth hormone receptor (GHR) and the growth differentiation factor-9 (GDF-9). METHODS: 54 and 46 samples of low and high milk yield groups, respectively, were collected. Detection of methylation was assessed in two CpG islands in the GDF-9 promoter via methylation-specific primer assay (MSP) and in one CpG island across the GHR promoter using combined bisulfite restriction analysis (COBRA). RESULTS: A positive correlation between the methylation pattern of GDF-9 and GHR and their expression levels was reported. Breeding season was significantly effective on both peak milk yield (PMY) and total milk yield (TMY), where March reported a higher significant difference in PMY than November. Whereas single birth was highly significant on TMY than multiple births. The 3rd and 4th parities reported the highest significant difference in PMY, while the 4th parity was the most effective one on TMY. CONCLUSION: These results may help improve the farm animals' milk productive efficiency and develop prospective epigenetic markers to improve milk yield by epigenetic marker-assisted selection (eMAS) in goat breeding programs.

Comparative analysis of Acomys cahirinus and Mus musculus responses to genotoxicity, oxidative stress, and inflammation.

The Egyptian spiny mouse, Acomys cahirinus, is a recently described model organism for regeneration studies. It has surprising powers of regeneration with relatively fast repairing mechanisms and reduced inflammation form compared to other mammals. Although several studies have documented the exceptional capabilities of Acomys to regenerate different tissues after injury, its response to different cellular and genetic stresses is not yet investigated. Therefore, the current study aimed to investigate Acomys abilities to resist genotoxicity, oxidative stress and inflammation induced by acute and subacute treatments with lead acetate. Responses of Acomys were compared with those of the lab mouse (Mus musculus), which displays signatures of the "typical" mammalian response to various stressors. Cellular and genetic stresses were induced by using acute and subacute doses of Lead acetate (400 mg/kg and 50 mg/kg for 5 days, respectively). The assessment of genotoxicity was carried out by using comet assay, while oxidative stress was evaluated by measuring the biomarkers; MDA, GSH and antioxidant enzymes CAT and SOD. Moreover, inflammation was assessed by analyzing the expression of some inflammatory-regeneration-related genes: CXCL1, IL1-ß, and Notch 2 and immunohistochemical staining of TNF-α protein in brain tissue, in addition to histopathological examination of brain, liver, and kidneys. The obtained results revealed a unique resistance potency of Acomys to genotoxicity, oxidative stress, and inflammation in certain tissues in comparison to Mus. Altogether, the results revealed an adaptive and protective response to cellular and genetic stresses in Acomys.

Normalization of nano-sized TiO2-induced clastogenicity, genotoxicity and mutagenicity by chlorophyllin administration in mice brain, liver, and bone marrow cells.

The intensive uses of titanium dioxide (TiO2) nanoparticles in sunscreens, toothpaste, sweats, medications, etc. making humans exposed to it daily by not little amounts and also increased its risks including genotoxicity. Thus, the present study was designed as one way to reduce nano-titanium-induced clastogenicity, genotoxicity, and mutagenicity in mice by co-administration of the free radical scavenger chlorophyllin (CHL). In addition, markers of oxidative stress were detected to shed more light on mechanism(s) underlying nano-sized TiO2 genotoxicity. Male mice were exposed to multiple injection into the abdominal cavity for five consecutive days with either CHL (40 mg/kg bw/day), or each of three dose levels of nano-sized TiO2 (500, 1000, or 2000 mg/kg bw/day) alone, or both simultaneously and sacrificed by cervical dislocation 24 h after the last treatment. After CHL co-administration, the observed dose-dependent genotoxicity of TiO2 nanoparticles indicated by the significant elevations in frequencies of both micronuclei and DNA damage induction was significantly decreased and returned to the negative control level. The observed induced mutations in p53 exons 5, 7, & 8 and 5 & 8 in the liver and brain, respectively, were declined in most cases. Moreover, CHL significantly decreased hepatic malondialdehyde level and significantly increased glutathione level and superoxide dismutase, catalase, and glutathione peroxidase activities that were significantly disrupted in animal groups treated with nano-TiO2 alone. In conclusion, the evidenced in vivo genotoxicity of nano-TiO2 in the present study was normalized after CHL co-administration which supports the previously suggested oxidative stress as the possible mechanism for titanium toxicity.

Evaluation of the role of the antioxidant silymarin in modulating the in vivo genotoxicity of the antiviral drug ribavirin in mice.

Ribavirin (1-ß-d-ribofuranosyl-1,2,4-triazole-3-carboxamide) is a widely used broad-spectrum antiviral drug. Recently, several reports revealed genotoxic effects of ribavirin in vivo and in vitro, which were correlated with the production of reactive oxygen species (ROS). This study aimed to evaluate the genotoxicity of ribavirin and to investigate the role of the natural antioxidant silymarin to modulate this genotoxicity. Male albino mice (age, 8-10 weeks) were injected intraperitoneally (i.p.) with ribavirin at three dose levels (20, 75 and 130 mg/kg bw) either in a single injection (acute treatment) or in multiple injections on five consecutive days (sub-acute treatment). Other comparable groups were treated with silymarin (70 mg/kg bw) 1h before the injection with ribavirin. Mice were sacrificed at different sampling times (24, 48 and 72 h) after the last ribavirin treatment. Micronucleus (MN) and single-strand conformation polymorphism (SSCP) assays were used to assess genotoxic and cytotoxic effects of ribavirin and to evaluate the protective effect of the pre-treatment with silymarin. Our results reveal genotoxic and cytotoxic effects of ribavirin in the MN assay. Pre-treatment with silymarin reduced the toxicity of ribavirin. In the SSCP assay, ribavirin treatment did not induce any mutations in the two selected sites in the D-loop of mitochondrial DNA (mtDNA).

Lead acetate and arsenic trioxide induce instability of microsatellites at three different fragile sites (6q21, 9q32-9q33 and 15p14) within the genome of the rat.

Human exposure to metals is of increasing concern due to the well-documented toxic and carcinogenic effects of metals and metal compounds, and the rising environmental levels due to industrial processes and pollution. It has been reported that metals can be genotoxic by several modes of action including generation of reactive oxygen species and inhibition of DNA repair. The aim of this study was to evaluate microsatellite instability (MSI) in three microsatellite loci (D6mit3, D9mit2 and D15Mgh1) located within three common fragile sites in the genome of the laboratory rat (6q21, 9q32-9q33 and 15p14) exposed to acute and chronic doses of a metal salt (lead acetate trihydrate) and a metalloid oxide (arsenic trioxide). In the acute and sub-chronic studies with the two compounds, MSI was observed in the three loci as deletions or additions of microsatellite repeats. The percentages of MSI were 36.4% and 42.1% for lead acetate and arsenic trioxide, respectively. Results of the present work indicate that the microsatellites located within fragile sites provide a convenient assay system to detect changes in DNA sequences resulting from exposure to genotoxic agents.

Microsatellite instability at three microsatellite loci (D6mit3, D9mit2 and D15Mgh1) located in different common fragile sites of rats exposed to cadmium.

Cadmium (Cd) is a non-essential element and is a widespread environmental pollutant. Exposure to cadmium can result in cytotoxic, carcinogenic and mutagenic effects. Mutagenesis is an indicative of genetic instability and can be assayed using microsatellites instability. The aim of the present study is to investigate; based on the rat model, the effects of oral acute (single 8.8mg/kg BW, 1/10 LD(50)) and sub-chronic (2.93mg/kg BW, 1/30 LD(50), for 4 weeks) doses of cadmium chloride on microsatellite instability at D6mit3, D9mit2 and D15Mgh1 loci, which are located in three different common fragile sites (6q21, 9q32-q33 and 15p14, respectively), within rat genome. In the acute study, no microsatellite instability (MSI) was observed in all the three tested loci (D6mit3, D9mit2 and D15Mgh1). In the sub-chronic study, the MSI were observed in the three studied loci and was in the form of deletion of 2-3bp or addition of 3-6bp. These finding may indicate the sensitivity of microsatellite sequences located at the fragile sites and the sensitivity of the simple sequence repeats (SSRs) assay for the detection of small variations in DNA sequence. However, additional chronic toxicological trials are needed in order to assess genotoxic effects of chronic exposure to Cd.

Beta-glucan inhibits the genotoxicity of cyclophosphamide, adriamycin and cisplatin.

The inhibitory effects of beta-glucan (betaG), one of the biological response modifiers, on the induction of chromosomal aberrations in the bone marrow and spermatogonial cells of mice treated with various anti-neoplastic drugs were investigated. beta-Glucan (100 mg/kg bw, i.p.) pre-treatment reduced the total number of cells with structural chromosomal aberrations scored after the treatment with cyclophosphamide (CP) (2.5 mg/kg bw, i.p.) adriamycin (ADR) (12 mg/kg bw, i.p.) and cis-diamminedichloroplatinum-II (cisplatin) (5 mg/kg bw, i.p.) by about 41.1, 26.9 and 57.7% in bone marrow and 44.4, 55 and 57.1% in spermatogonial cells, respectively. This protective effect of beta-glucan could be attributed to its scavenging ability to trap free-radicals produced during the biotransformation of these anti-neoplastic drugs. Beta-glucan also markedly restored the mitotic activity of bone marrow cells that had been suppressed by the anti-neoplastic drugs. These results indicate that in addition to the known immunopotentiating activity of beta-glucan, it plays a role in reducing genotoxicity induced by anti-neoplastic drugs during cancer chemotherapy.