Is the Comet Assay a Sensitive Procedure for Detecting Genotoxicity?

Although the Comet assay, a procedure for quantitating DNA damage in mammalian cells, is considered sensitive, it has never been ascertained that its sensitivity is higher than the sensitivity of other genotoxicity assays in mammalian cells. To determine whether the power of the Comet assay to detect a low level of genotoxic potential is superior to those of other genotoxicity assays in mammalian cells, we compared the results of Comet assay with those of micronucleus test (MN test). WTK1 human lymphoblastoid cells were exposed to methyl nitrosourea (MNU), ethyl nitrosourea (ENU), methyl methanesulfonate (MMS), ethyl methanesulfonate (EMS), bleomycin (BLM), or UVC. In Comet assay, cells were exposed to each mutagen with (Comet assay/araC) and without (Comet assay) DNA repair inhibitors (araC and hydroxyurea). Furthermore, acellular Comet assay (acellular assay) was performed to determine how single-strand breaks (SSBs) as the initial damage contributes to DNA migration and/or to micronucleus formation. The lowest genotoxic dose (LGD), which is defined as the lowest dose at which each mutagen causes a positive response on each genotoxicity assay, was used to compare the power of the Comet assay to detect a low level of genotoxic potential and that of MN test; that is, a low LGD indicates a high power. Results are summarized as follows: (1) for all mutagens studied, LGDs were MN test ≦ Comet assay; (2) except for BLM, LGDs were Comet assay/araC ≦ MN test; (3) except for UVC and MNU, LGDs were acellular assay ≦ Comet assay/araC ≦ MN test ≦ Comet assay. The following is suggested by the present findings: (1) LGD in the Comet assay is higher than that in MN test, which suggests that the power of the MN test to detect a low level of genotoxic potential is superior to that of the Comet assay; (2) for the studied mutagens, all assays were able to detect all mutagens correctly, which suggests that the sensitivity of the Comet assay and that of the MN test were exactly identical; (3) the power of the Comet assay to detect a low level of genotoxic potential can be elevated to a level higher than that of MN test by using DNA resynthesis inhibitors, such as araC and HU

JSPS-10 The Effect of Consumption of Raw Chicken Meat on Humoral Immunity against Campylobacter jejuni in veterinarians and workers in a chicken processing plant

Campylobacter jejuni and C. coli are the leading cause of enteric infections in Japan and many other developed countries, and the public health burden of campylobacteriosis is increasing [1]. Although the epidemiological data in Japan is based on passive surveillance, approximately 2,000 to 3,000 cases per each year have been reported as a foodborne infection since 1982. Many risk factors for Campylobacter transmission have been identified. Handling and consumption of poultry meat are often causing of infection [2, 3]. Since Japanese have a food habitant to eat fresh raw "free-range" chicken meat and liver, the risk for infection with campylobacters may be high [4]. However, little is known about the relationship between consumption of raw chicken meat and humoral immunity against C. jejuni in humans. When people had been exposed to campylobacters contaminated in water or foods, it has been reported that their antibodies were rising [5]. This study was conducted by analyzing the antibody level against C. jejuni with questionnaires from 74 veterinarians who worked as a meat inspector and 181 workers from a chicken processing plant

Effects of fruit skin and water temperature during soaking before germination on the emergence rates of common buckwheat

The studies focused effects of the presence of fruit skin (hull or pericarp) and water temperature during water soaking before germination on the emergence rates of common buckwheat (Fagophyrum esculentum Moench) after seeding. We aimed to understand the mechanisms underlying the poor emergence rates that have been observed after water flooding before germination. Shinano No.1 was exposed to water soaking treatments at temperatures of 10,15,20, or 25℃ for 3 days. After soaking, the seeds were grown at 20℃, and the percentages of emerged seedlings were investigated 7 days after seeding. Dehulled seeds and normal seeds were soaked for 4 days at 25℃, and the contents of dissolved oxygen were measured in the water. The emergence rates of normal intact seeds (fruits)decreased significantly (p＜0.01)with an increase in soaking water temperature before germination. The emergence rates of dehulled seeds improved after removing the fruit skin, and it reached 70%,even at 25℃.Soaking treatment for 96 h at 25℃ decreased the emergence rates of normal seeds and dehulled seeds. The emergence rate of normal seeds was significantly lower than that of dehulled seeds (p＜0.001). Moreover, there was no difference in the emergence rates of dehulled seeds between plots with or without daily water replacement. The contents of dissolved oxygen in the water at 25℃ did not differ between normal seeds and dehulled seeds after 50h. These results suggested that high temperatures affected embryo viability and that the relative mechanical resistance of the fruit skin on the embryo directly affected the seed emergence rate.Article信州大学農学部AFC報告 13: 113-118 (2015)departmental bulletin pape

Working from home and dietary changes during the COVID-19 pandemic: A longitudinal study of health app (CALO mama) users

It is plausible that the coronavirus disease pandemic and related changes in work and life patterns affected dietary patterns, but existing studies have limitations owing to a cross-sectional design. Using longitudinal data, we examined dietary changes in people due to the pandemic and work and life patterns. We conducted an online survey on changes in work and life patterns during the pandemic from April 30, 2020, to May 8, 2020, among users of a health app called CALO mama provided in Japan. We retrieved and linked the dietary data for 5929 participants from January 1, 2020, to May 13, 2020. Generalized linear mixed models were used to estimate the frequencies of food intake associated with the pandemic and work and life patterns. During the state of emergency, the frequency of intake of vegetables, beans, seaweeds, fish, meats, dairy products, and snacks increased, whereas alcohol intake decreased. Working from home was associated with increased intake of vegetables, fruits, dairy products, and snacks but decreased intake of seaweeds, meats, and alcohol. Time spent on childcare was associated with decreased intake of vegetables and fruits but increased intake of meats. Probable depressive symptoms were negatively associated with the frequency of food intake other than snacks and alcohol. We conclude that diet quality improved during the pandemic in general, but attention must be paid to overconsumption of snacks and negative factors such as increased burden of childcare and depression for healthy eating

HSP90α plays an important role in piRNA biogenesis and retrotransposon repression in mouse

HSP90, found in all kingdoms of life, is a major chaperone protein regulating many client proteins. We demonstrated that HSP90α, one of two paralogs duplicated in vertebrates, plays an important role in the biogenesis of fetal PIWI-interacting RNAs (piRNA), which act against the transposon activities, in mouse male germ cells. The knockout mutation of Hsp90α resulted in a large reduction in the expression of primary and secondary piRNAs and mislocalization of MIWI2, a PIWI homolog. Whereas the mutation in Fkbp6 encoding a co-chaperone reduced piRNAs of 28–32 nucleotides in length, the Hsp90α mutation reduced piRNAs of 24–32 nucleotides, suggesting the presence of both FKBP6-dependent and -independent actions of HSP90α. Although DNA methylation and mRNA levels of L1 retrotransposon were largely unchanged in the Hsp90α mutant testes, the L1-encoded protein was increased, suggesting the presence of post-transcriptional regulation. This study revealed the specialized function of the HSP90α isofom in the piRNA biogenesis and repression of retrotransposons during the development of male germ cells in mammals

Organ accumulation and carcinogenicity of highly dispersed multi-walled carbon nanotubes administered intravenously in transgenic rasH2 mice

Purpose: Multiwalled carbon nanotubes (MWCNTs) have been known to enter the circulatory system via the lungs from inhalation exposure; however, its carcinogenicity and subsequent accumulation in other organs have not been adequately reported in the literature. Moreover, the safety of MWCNTs as a biomaterial has remained a matter of debate, particularly when the material enters the circulatory system. To address these problems, we used carcinogenic rasH2 transgenic mice to intravenously administer highly dispersed MWCNTs and to evaluate their carcinogenicity and accumulation in the organs. Methods: Two types of MWCNTs (thin-and thick-MWCNTs) were intravenously administered at a high dose (approximately 0.7 mg per kg body weight) and low dose (approximately 0.07 mg per kg body weight). Results: MWCNTs showed pancreatic accumulation in 3.2% of mice administered with MWCNTs, but there was no accumulation in other organs. In addition, there was no significant difference in the incidence of tumor among the four MWCNTs-administered groups compared to the vehicle group without MWCNTs administration. Blood tests revealed elevated levels in mean red blood cell volume and mean red blood cell hemoglobin level for the MWCNTs-administered group, in addition to an increase in eotaxin. Conclusion: The present study demonstrated that the use of current technology to sufficiently disperse MWCNTs resulted in minimal organ accumulation with no evidence of carcinogenicity.ArticleINTERNATIONAL JOURNAL OF NANOMEDICINE. 14:6465-6480 (2019)journal articl