Molecular cytogenetic screening of sex chromosome abnormalities in young horse populations.

BACKGROUND: Chromosomal abnormalities occur in the equine population at a rate of approximately 2%. The use of molecular cytogenetic techniques allows a more accurate identification of chromosomal abnormalities, especially those with a low rate of abnormal metaphases, demonstrating that the actual incidence in equine populations is higher. OBJECTIVES: Estimation of the number of carriers of karyotypic abnormalities in a sample from a population of young horses of various breeds, using molecular cytogenetic techniques. STUDY DESIGN: Cross-sectional. METHODS: Venous blood samples were collected from 500 young horses representing 5 breeds (Purebred Arabian, Hucul, Polish primitive horse [Konik], Malopolska, Coldblood, Silesian). Chromosomes and DNA were obtained from blood lymphocytes and evaluated by fluorescence in situ hybridisation (FISH) and PCR, using probes and markers for the sex chromosomes and select autosomes. RESULTS: Nineteen horses, 18 mares and 1 stallion, were diagnosed with different chromosomal abnormalities: 17 cases of mosaic forms of sex chromosome aneuploidies with a very low incidence (0.6%-4.7%), one case of a SRY-negative 64,XY sex reversal mare, and one mare with X-autosome translocation. The percentage of sex chromosomal aberrations was established as 3.8% in the whole population, 6.08% in females and 0.49% in males. MAIN LIMITATIONS: Limited sample size, confined to horses from Poland. CONCLUSIONS: The rate of sex chromosomal abnormalities we identified was almost double that reported in previous population studies that used classical chromosome staining techniques. FISH allowed the detection of aneuploid cell lines which had a very low incidence. The FISH technique is a faster and more precise method for karyotype examination; however, it is usually focused on only one or two chromosomes while banding karyotyping includes the entire chromosome set.

Chromosomal aberration analysis: Novel noninvasive techniques for early-stage cancer screening.

OBJECTIVE: Chromosome breakage is a catastrophic event that leads to the progressive development and progression of cancer. In order to analyze the changes of peripheral blood microenvironment of tumor patients, to explore the indicators of non-specific non-invasive tumor early screening. This paper presents a new idea of whether the gene sequence near the DNA damage break point is the gene sequence that controls the unrestricted growth of normal cells. METHODS: The chromosomal aberrations of peripheral blood lymphocytes were analysed in 60 healthy adult and 49 cancer patients before radiotherapy. RESULTS: The detection rate of chromosomal aberrations was high in tumor patients, and "dicentric + translocations" of chromosomes were detected in 36 patients (73.47 %). The chi-square test showed statistically significant differences (P < 0.01), and chromosome adhesion and dissolution were observed. CONCLUSIONS: "Dicentric + Translocation" chromosome can be used as a nonspecific early screening indicator for cancer. This is worthy of further study. This index can be used to determine the genetic basis of various cancers at the gene level to modify the base sequence and prevent the occurrence of cancer. It is worthy of further study, and it can provide a new method for gene therapy of tumors.

Toxicity Assessment of a No-Pain Pharmacopuncture Extract Using a Standard Battery of In Vitro Chromosome Aberration Tests.

Objectives: Genotoxicity is evaluated through a chromosomal aberration test using cultured mammalian cells to determine the toxicity of no-pain pharmacopuncture (NPP), which has recently been used to treat musculoskeletal pain disorders in Korean medical clinical practice. Methods: An initial test was performed to determine the dosage range of the NPP, followed by the main test. In this study, NPP doses of 10.0, 5.0, and 2.5%, and negative and positive controls were tested. An in vitro chromosome aberration test was performed using Chinese hamster lung cells under short-term treatment with or without metabolic activation and under continuous treatment without metabolic activation. Results: Compared with the saline negative control group, NPP did not significantly increase the frequency of chromosomal abnormalities in Chinese hamster lung cells, regardless of the presence or absence of metabolic activation. Additionally, the number of cells with structural chromosomal abnormalities was significantly higher in the positive control group than that in the negative control group that received saline. Conclusion: Based on the above results, the chromosomal abnormality-producing effect of NPP was determined to be negative under these test conditions.

Contribution of radioactive particles to the post-explosion exposure of atomic bomb survivors implied from their stable chromosome aberration rates.

Even today when nearly 80 years have passed after the atomic bomb (A-bomb) was dropped, there are still debates about the exact doses received by the A-bomb survivors. While initial airborne kerma radiation (or energy spectrum of emitted radiation) can be measured with sufficient accuracy to assess the radiation dose to A-bomb survivors, it is not easy to accurately assess the neutron dose including appropriate weighting of neutron absorbed dose. Particularly, possible post-explosion exposure due to the radioactive particles generated through neutron activation have been almost neglected so far, mainly because of a large uncertainty associated to the behavior of those particles. However, it has been supposed that contribution of such non-initial radiation exposure from the neutron-induced radioactive particles could be significant, according to the findings that the stable chromosomal aberration rates which indicate average whole-body radiation doses were found to be more than 30% higher for those exposed indoors than for those outdoors even at the same initial dose estimated for the Life Span Study. In this Mini Review article, the authors explain that such apparently controversial observations can be reasonably explained by assuming a higher production rate of neutron-induced radioactive particles in the indoor environment near the hypocenter.

Symbiotic microbial communities in various locations of the lung cancer respiratory tract along with potential host immunological processes affected.

Lung cancer has the highest mortality rate among all cancers worldwide. The 5-year overall survival rate for non-small cell lung cancer (NSCLC) is estimated at around 26%, whereas for small cell lung cancer (SCLC), the survival rate is only approximately 7%. This disease places a significant financial and psychological burden on individuals worldwide. The symbiotic microbiota in the human body has been significantly associated with the occurrence, progression, and prognosis of various diseases, such as asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis. Studies have demonstrated that respiratory symbiotic microorganisms and their metabolites play a crucial role in modulating immune function and contributing to the pathophysiology of lung cancer through their interactions with the host. In this review, we provide a comprehensive overview of the microbial characteristics associated with lung cancer, with a focus on the respiratory tract microbiota from different locations, including saliva, sputum, bronchoalveolar lavage fluid (BALF), bronchial brush samples, and tissue. We describe the respiratory tract microbiota's biodiversity characteristics by anatomical region, elucidating distinct pathological features, staging, metastasis, host chromosomal mutations, immune therapies, and the differentiated symbiotic microbiota under the influence of environmental factors. Our exploration investigates the intrinsic mechanisms linking the microbiota and its host. Furthermore, we have also provided a comprehensive review of the immune mechanisms by which microbiota are implicated in the development of lung cancer. Dysbiosis of the respiratory microbiota can promote or inhibit tumor progression through various mechanisms, including DNA damage and genomic instability, activation and regulation of the innate and adaptive immune systems, and stimulation of epithelial cells leading to the upregulation of carcinogenesis-related pathways.

Mutagenicity and safety evaluation of Ashwagandha (Withania somnifera) root aqueous extract in different models.

Withania somnifera (Ashwagandha) also called as Indian ginseng, a revered herb from Indian traditional system of medicine is a rejuvenator and tonic (Rasayana) used for its varied benefits. The roots of ashwagandha exhibit properties like anti-inflammatory, aphrodisiac, anthelmintic, astringent, diuretic, stimulant and thermogenic. However, data of ashwagandha on its mutagenic effects are lacking. In the present study, in-vitro genotoxicity tests were used to evaluate the mutagenic potential of Ashwagandha Root Extract (ARE). Concentrations of 0.156 to 5.00 mg/plate ARE were used for conducting Bacterial reverse mutation test (BRMT). For chromosome aberration (CA) test ARE was used in concentrations of 0.25 to 2.00 mg/ml, and for micronucleus (MN) tests ARE concentrations of 500/1000/2000 mg/kg were used. Acute oral toxicity was conducted in Wistar rats (n = 25) as per the OECD guideline (#423) with doses of 500/1000/2000 mg/kg body weight in male Swiss albino mice for morbidity and mortality for 3 days. The BRMT and CA tests were conducted with and without metabolic activation (S9). The study was approved by the institutional ethics committee (IEC) and institutional animal ethics committee (IAEC). ARE failed to show any mutagenic effects up to a dose of 5 mg/plate in BRMT. Also, ARE did not show any clastogenic activity in doses up to 2 mg/ml in CA test and in micronucleus test up to 2000 mg/kg body weight. These results were observed with and without metabolic activation (S9) under the stated experimental conditions. No mortality, morbidity, or any clinical signs were observed up to 3 days following ARE administration. Ashwagandha root extract failed to show any mortality in doses up to 2000 mg/kg oral dosage and did not show any mutagenic (genotoxic) effects in high concentrations.

Guidance for the use and interpretation of assays for monitoring anti-genotoxicity.

Since DNA damage can occur spontaneously or be produced by the environmental genotoxins in living cells, it is important to investigate compounds that can reverse or protect DNA damage. An appropriate methodology is essential for the responsive identification of protection offered against DNA damage. This review includes information on the current state of knowledge on prokaryotic cell-based assays (SOS chromotest, umu test, vitotox assay) and cytogenetic techniques (micronucleus assay, chromosome aberration test and sister chromatid exchange assay) with an emphasis on the possibility to explore genoprotective compounds. Throughout the last decade, studies have extrapolated the scientific methodologies utilized for genotoxicity to assess genoprotective compounds. Therefore, shortcomings of genotoxicity studies are also mirrored in antigenotoxicity studies. While regulatory authorities around the world (OECD, US-EPA and ICH) continue to update diverse genotoxic assay strategies, there are still no clear guidelines/approaches for efficient experimental design to screen genoprotective compounds. As a consequence, non-synergetic and inconsistent implementation of the test method by the researchers to execute such simulations has been adopted, which inevitably results in unreliable findings. The review has made the first attempt to collect various facets of experimentally verified approaches for evaluating genoprotective compounds, as well as to acknowledge potential significance and constraints, and further focus on the assessment of end points which are required to validate such action. Henceforth, the review makes an incredible commitment by permitting readers to equate several components of their test arrangement with the provided simplified information, allowing the selection of convenient technique for the predefined compound from a central repository.

In vitro and in vivo evaluation of the genotoxicity of titanium dioxide, GST.

Titanium dioxide (TiO2) was used in various applications in a wide range of products including food, cosmetics and photocatalyst. General toxicity studies of titanium dioxide, GST (Green Sludge Titanium) have been investigated in several reports, whereas studies concerning mutagenicity and genotoxicity have not been elucidated. Herein, we investigated the potential mutagenicity and genotoxicity of GST by genetic toxicology testing. The bacterial reverse mutation test was conducted by the pre-incubation method in the presence and absence of metabolic activation system (S9 mixture). The chromosome aberration test was performed using cultured Chinese hamster lung cell line in the absence and presence of S9 mixture. The micronucleus test was performed by using specific pathogen-free male ICR mice. Genotoxicity tests were conducted following the test guidelines of the Organisation for Economic Cooperation and Development with application of Good Laboratory Practice. No statistically significant increases were found in the bacterial reverse mutation test, in vitro chromosome aberration test, and in vivo micronucleus test when tested for induction of genotoxicity in GST. These results suggest that GST did not induce mutagenicity and genotoxicity in both in vitro and in vivo system.

Uniparental disomy: expanding the clinical and molecular phenotypes of whole chromosomes.

Uniparental disomy (UPD) refers to as both homologous chromosomes inherited from only one parent without identical copies from the other parent. Studies on clinical phenotypes in UPDs are usually focused on the documented UPD 6, 7, 11, 14, 15, and 20, which directly lead to imprinting disorders. This study describes clinical phenotypes and genetic findings of three patients with UPD 2, 9, and 14, respectively. Chromosomal microarray (CMA), UPDtool, methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) and whole-exome sequencing (WES) analysis were performed to characterize the genetic etiology. The CMA revealed a homozygous region involving the whole chromosome 2 and 9, a partial region of homozygosity in chromosome 14. UPD-tool revealed a paternal origin of the UPD2. MS-MLPA showed hypomethylation of imprinting gene MEG3 from maternal origin in the UPD14 case. In addition, UPD14 case displayed complex symptoms including growth failure, hypotonia and acute respiratory distress syndrome (ARDS), accompanied by several gene mutations with heterozygous genotype by WES analysis. Furthermore, we reviewed the documented UPDs and summarized the clinical characteristics and prognosis. This study highlighted the importance to confirm the diagnosis and origin of UPD using genetic testing. Therefore, it is suggested that expanding of the detailed phenotypes and genotypes provide effective guidance for molecule testing and genetic counseling, and promote further biological investigation to the underlying mechanisms of imprinted disorders and accompanied copy number variations.

[Analysis of chromosome aberrations in peripheral blood lymphocyte of medical radiation workers in a tertiary hospital].

Objective: To analyze the level of chromosome aberration in lymphocytes of medical radiation workers and its influencing factors. Methods: From July to September 2020, 252 medical workers in a tertiary hospital were selected as the study subjects and 107 preserviceworkers were selected as the control group. The Chromosomal aberrations of peripheral blood lymphocytes were measured using conventional cytogenetic analysis method, and the differences were analyzed. Results: The frequencies of dicentric puls centric ring, total chromosome-type aberrations, and abnormal detection rate in the radiation group were significantly higher than those in the control group (Z=2.59, 3.74, 9.99, P<0.05). There was significant difference in the frequencies of dicentric plus centric ring and total chromosome-type aberrations among different types of work (χ(2)=8.59, 8.17, 11.39, P<0.05), and the frequencies of dicentric plus centric ring were significantly higher in the interventional radiology group than those in diagnostic radiology (χ(2)=2.90, P<0.05), While the rates of acentric fragment and total chromosome-type aberrations were significantly higher in the nuclear medicine group than those in diagnostic radiology (χ(2)=2.81, 3.19, P<0.05). The difference in the abnormal detection rate of chromosome aberrations between different types of work was statistically significant (P<0.05), and the rate in the interventional radiology group was significantly higher than that in the diagnostic radiology group (χ(2)=7.66, P<0.05). There was no significant difference in chromosome aberration level and abnormal detection rate among different working ages (P>0.05). Poisson regression analysis indicated that the type of work is a risk factor for chromosomal aberration [IRR=2.31 (nuclear medicine group), 1.66 (Radiation therapy), and 1.78 (interventional group) ; P<0.05]. Conclusion: Ionizing radiation causes certain radiation damage to medical radiology workers, and the frequencies of chromosome aberration in the radiation workers of nuclear medicine and interventional radiology groups are relatively high, so radiation protection should be strengthened to ensure the health of relevant workers.

Risk factor analysis for adverse prognosis of the fetal ventricular septal defect (VSD).

BACKGROUND: Ventricular septal defect (VSD) is the most common subtype of congenital heart disease. In the present study, we aimed to determine whether chromosome aberration was associated with the occurrence of VSD and evaluate the association of VSD size, location and chromosome aberration with adverse outcomes in the Chinese fetuses. METHODS: Fetuses with VSD and comprehensive follow-up data were included and evaluated retrospectively. Medical records were used to collect epidemiological data and foetal outcomes. For VSD fetuses, conventional karyotype and microarray analysis were conducted. After adjusting confounding factors by using multivariable logistic regression analyses, the association between chromosome variations and VSD occurrence was explored. The association between defect size, location and chromosome aberrations and adverse foetal outcomes was also investigated. RESULTS: Chromosome aberration was the risk factor for VSD occurrence, raising 6.5-fold chance of developing VSD. Chromosome aberration, peri-membranous site and large defect size of VSD were significant risk factors of adverse fetal outcome. Chromosome aberrations, including pathogenic copy number variations (CNVs) and variations of uncertain significance (VUS), were both risk factors, increasing the risk of the adverse fetal outcome by 55.9 times and 6.7 times, respectively. The peri-membranous site would increase 5.3-fold risk and defects larger than 5 mm would increase the 7.1-fold risk for poor fetal outcome. CONCLUSIONS: The current investigation revealed that chromosomal abnormalities, large defects, and the peri-membranous site were all risk factors for poor fetal outcomes. Our study also indicated that chromosome aberration was one of risk factors for the VSD occurrence.

The toxic mechanism of tetracycline on root tips in hulless barley (Hordeum vulgare L. var. nudum).

Tetracycline (TC) is a commonly used antibiotic that affects various physiological processes in plants. However, its negative effects on plants remain poorly understood at the molecular level. To ascertain the TC toxicity in the roots, transcriptomic, cytological, and physiological analyses were performed to explore the molecular mechanisms of TC influencing the growth of hulless barley root. At a low concentration (1 mg/L), TC promoted root growth by upregulating the genes related to the flavonoid pathway. At high concentrations (10, 100, and 200 mg/L), TC downregulated genes related to homologous recombination in the root meristem zone and inhibited the mitosis index by 16.4%. Disruption of the DNA repair process can lead to chromosomal aberrations, resulting in a 6.8% C-mitosis rate in the most severe cases. Finally, root growth was inhibited by TC, as evidenced by a reduction in root viability, an increase in reactive oxygen species content, and an inhibition of root length. Cross-comparison of physiological and cytological characterizations and transcriptomic information revealed changes in genetic processes under TC stress. Overall, we present an early genetic strategy to study the significant influence of TC stress on roots.

Multicentric evaluation of conventional dosimetry vs bio-dosimetry over a period of two years for a three-point contact.

Background: Dental radiology represents the best model for evaluating the effects of low-dose ionizing radiation. Therefore, this study evaluated the awareness on radiation hygiene among dental ancillary personnel through a questionnaire and their absorbed doses by physical and biologic dosimetry. Methods: The multicentric study included two groups. Group I (N = 30) consisted of dental staff involved in dental radiology. An equal number of personnel who were not related to radiology formed the control group. Knowledge (K), attitude (A), and practice (P) of participants were assessed using a KAP questionnaire. Radiation exposure was evaluated by physical dosimetry at 3 time periods: at the beginning of the study (T1), after 10 months (T2), and at the end after 20 months (T3). Similarly, biologic dosimetry was also carried out at 3 time points by dicentric chromosome aberration assay. The data were compared using percentage analysis, analysis of variance (one-way analysis of variance), and Student's t- test. Results: The KAP survey demonstrated enhanced understanding of radiation protection measures and its sound practice by the participants. Physical dosimetry showed a significant increase in absorbed dose at 3 time points: T1, T2, and T3. However, no chromosomal aberrations were observed in blood lymphocytes for any of the participants in the optimized 4-day biodosimetry protocol. Conclusion: Good radiation protection protocols-safe distance from the radiation source and wear of lead aprons and thyroid collars-ensured low absorbed doses. The 4-day protocol is an important step toward developing biodosimetry laboratories in the Armed Forces Medical Services for clinical and national radiation countermeasure strategies.

Modeling of ionizing radiation-induced chromosome aberration and tumor prevalence based on two classes of DNA double-strand breaks clustering in chromatin domains.

There has been some controversy over the use of radiobiological models when modeling the dose-response curves of ionizing radiation (IR)-induced chromosome aberration and tumor prevalence, as those curves usually show obvious non-targeted effects (NTEs) at low doses of high linear energy transfer (LET) radiation. The lack of understanding the contribution of NTEs to IR-induced carcinogenesis can lead to distinct deviations of relative biological effectiveness (RBE) estimations of carcinogenic potential, which are widely used in radiation risk assessment and radiation protection. In this work, based on the initial pattern of two classes of IR-induced DNA double-strand breaks (DSBs) clustering in chromatin domains and the subsequent incorrect repair processes, we proposed a novel radiobiological model to describe the dose-response curves of two carcinogenic-related endpoints within the same theoretical framework. The representative experimental data was used to verify the consistency and validity of the present model. The fitting results indicated that, compared with targeted effect (TE) and NTE models, the current model has better fitting ability when dealing with the experimental data of chromosome aberration and tumor prevalence induced by multiple types of IR with different LETs. Notably, the present model without introducing an NTE term was adequate to describe the dose-response curves of IR-induced chromosome aberration and tumor prevalence with NTEs in low-dose regions. Based on the fitting parameters, the LET-dependent RBE values were calculated for three given low doses. Our results showed that the RBE values predicted by the current model gradually decrease with the increase of doses for the endpoints of chromosome aberration and tumor prevalence. In addition, the calculated RBE was also compared with those evaluated from other models. These analyses show that the proposed model can be used as an alternative tool to well describe dose-response curves of multiple carcinogenic-related endpoints and effectively estimate RBE in low-dose regions.

Linking Benzene, in Utero Carcinogenicity and Fetal Hematopoietic Stem Cell Niches: A Mechanistic Review.

Previous research reported that prolonged benzene exposure during in utero fetal development causes greater fetal abnormalities than in adult-stage exposure. This phenomenon increases the risk for disease development at the fetal stage, particularly carcinogenesis, which is mainly associated with hematological malignancies. Benzene has been reported to potentially act via multiple modes of action that target the hematopoietic stem cell (HSCs) niche, a complex microenvironment in which HSCs and multilineage hematopoietic stem and progenitor cells (HSPCs) reside. Oxidative stress, chromosomal aberration and epigenetic modification are among the known mechanisms mediating benzene-induced genetic and epigenetic modification in fetal stem cells leading to in utero carcinogenesis. Hence, it is crucial to monitor exposure to carcinogenic benzene via environmental, occupational or lifestyle factors among pregnant women. Benzene is a well-known cause of adult leukemia. However, proof of benzene involvement with childhood leukemia remains scarce despite previously reported research linking incidences of hematological disorders and maternal benzene exposure. Furthermore, accumulating evidence has shown that maternal benzene exposure is able to alter the developmental and functional properties of HSPCs, leading to hematological disorders in fetus and children. Since HSPCs are parental blood cells that regulate hematopoiesis during the fetal and adult stages, benzene exposure that targets HSPCs may induce damage to the population and trigger the development of hematological diseases. Therefore, the mechanism of in utero carcinogenicity by benzene in targeting fetal HSPCs is the primary focus of this review.

Acute toxicity and genotoxicity studies on new melatonergic antidepressant GW117.

GW117, a novel derivate compound of agomelatine that acts as both a 5-HT2C receptor antagonist and a MT1/MT2 receptor agonist, likely underlines the potent antidepressant action with less hepatotoxicity than agomelatine. We evaluated the acute toxicity of GW117, and the genotoxicity of GW117 using bacterial reverse mutation test, mammalian chromosomal aberration test in Chinese hamster lung cells (CHL) and mouse bone marrow micronucleus test. The acute toxicity test results showed that maximum tolerated dose (MTD) of GW117 was 2000 mg/kg, under which mean Cmax and AUC0→t was 10,782 ng/mL and 81,046 ng/mL × h, respectively. The result of bacterial reverse mutation test showed that the number of bacterial colonies in each dose group of GW117 did not increase significantly compared with that in the solvent control group with or without S9 metabolic activation system. In vitro chromosome aberration test of CHL cells, the chromosome aberration rate of each dose group of GW117 did not increase with or without S9 metabolic activation system. In mouse micronucleus test, the highest dose was 2000 mg/kg, the micronucleus rate did not increase significantly. Under the conditions of this study, the MTD of a single GW117 administration was 2000 mg/kg, there was no genotoxicity effect of GW117.

Protective Effects of Arbutus unedo L. Honey in the Alleviation of Irinotecan-Induced Cytogenetic Damage in Human Lymphocytes-An In Vitro Study.

Strawberry tree (Arbutus unedo L.) honey (STH) has been used since ancient times as a folk medicine remedy, especially in certain Mediterranean countries. This honey, rich in phenolic content, is well recognized for its antioxidant, anti-inflammatory, and antimicrobial activities, and is used for the treatment of skin lesions as well as gastrointestinal and respiratory disorders. This study investigated whether STH alleviates genome damage in human peripheral blood lymphocytes produced by the cytotoxic drug irinotecan. The phenolic profile of STH was previously estimated by ultra-high-performance liquid chromatography coupled to a linear ion trap-Orbitrap hybrid mass spectrometer. The effects of STH were evaluated at three concentrations (1×, 5×, and 10×), based on the daily consumption of the honey by an adult person. After 2 h of in vitro exposure, standard lymphocyte cultures for the analysis of chromosome aberrations and the cytokinesis-block micronucleus cytome assay were established. Our results demonstrate that STH offered remarkable geno- and cytoprotection when administered with irinotecan. These findings are relevant for drawing preliminary conclusions regarding the in vitro safety of the tested honey. However, further studies are needed with the application of more complex experimental models.

Translocations are induced in hematopoietic stem cells after irradiation of fetal mice.

Although mammalian fetuses have been suggested to be sensitive to radiation, an increased frequency of translocations was not observed in blood lymphocytes from atomic bomb (A-bomb) survivors who were exposed to the bomb in utero and examined as adults. Since experiments using hematopoietic cells of mice and rats confirmed this finding, it was hypothesized that either irradiated fetal hematopoietic stem cells (f-HSCs) cannot generate exchange-type chromosomal aberrations or cells bearing induced aberrations are eliminated before the animals reach adulthood. In the present study, pregnant mice (12.5-15.5 days post coitum [dpc]) were irradiated with 2 Gy of X-rays and long-term HSCs (LT-HSCs) were isolated 24 h later. Multicolor fluorescence in situ hybridization (mFISH) analysis of LT-HSC clones proliferated in vitro showed that nine out of 43 (21%) clones from fetuses and 21 out of 41 (51%) clones from mothers bore translocations. These results indicate that cells with translocations can arise in mouse f-HSCs but exist at a lower frequency than in the mothers 24 h after X-ray exposure. Thus, it seems likely that translocation-bearing f-HSCs are generated but subsequently disappear, so that the frequency of lymphocyte translocations may decrease and reach the control level by the time the animals reach adulthood.

FISH with Whole Chromosome Painting Probes.

Some types of chromosome aberrations are not easily identified by the traditional Giemsa staining. It usually needs some banding technique and skilled person's eye. Whole chromosome painting FISH probe can stain designated entire chromosomes or domains in metaphase chromosomes or interphase nuclei, respectively. It allows to visually identify translocations, deletions, or amplifications of specific chromosomes. Once chromosomes are stained, even non-skilled researchers can easily identify those chromosome aberrations. Whole chromosome painting FISH has higher sensitivity to detect chromosome aberrations. This chapter introduces the method for whole chromosome painting FISH staining.

In vitro screening of genotoxicity and mutagenicity of pyriproxyfen in human lymphocytes and Salmonella typhimurium TA98 and TA100 strains.

Pyriproxyfen (PPX) is a pesticide/larvicide used to increase productivity in agriculture against insects by inhibiting development of insects' larvae. In this study, cytotoxic, genotoxic, and mutagenic effects of PPX were investigated in human peripheral lymphocytes and Salmonella typhimurium strains by performing chromosomal aberration, micronucleus (MN) tests, and Ames test, respectively. For the chromosome aberration (CA) and MN methods, blood from four healthy donors (two men and two women, nonsmokers) were used. Two hundred microliters of blood was inoculated into PbMax medium and prepared according to International Guidelines. For the Ames test, S. typhimurium TA98 and TA100 strains were used to detect frameshift and base pair substitution mutagens, respectively. PPX induced both the CA percentage and MN frequency in human peripheral lymphocytes and exhibited cytotoxic effects. In addition, it showed a mutagenic effect at all doses in TA98 and TA100 strains in the presence of S9mix; however, no such effect was observed in the absence of S9mix. According to the obtained results, it can be said that PPX has genotoxic and mutagenic potentials.