2025年12月 Student Monthly Progress を開催しました

12月19日 (金)にStudent Monthly Progressが開催されました。4名の大学院生が研究内容について発表しました。

 

【発表者】

1. Natamon Jianpraphat: Laboratory of Toxicology

<Evaluation of Neonicotinoid-Induced Neurotoxic Effects Using Human Dopaminergic Neurons>

 

2. Kwadwo Boateng: Division of International Research Promotion

<Epidemiological studies of orthomarburgvirus infection in Egyptian fruit bats in Ghana and Israel>

 

3. Ryusuke Tsushima:  Laboratory of Theriogenology

<Development of reversible and non-invasive methods of reproductive suppression for population management in primates>

 

4. Charlotte Poussier: Division of Bioresources

<Gepotidacin as a promising treatment alternative against fluoroquinolone-resistant Salmonella Typhimurium infections>

 

【座長】

Pavani H. K. Senarathne Krishnadas Mudiyanselage: Institute for Genetic Medicine

Mawiini Mwandabantu: Laboratory of Theriogenology

 

 

 

   

❖座長レポート❖

 

《EvaluationEvaluation of neonicotinoid-induced neurotoxic effects using human dopaminergic neurons》

Natamon Jianpraphat

 

 

 

Natamon presented progress on investigating the neurotoxic effects of the neonicotinoid insecticide clothianidin using human dopaminergic LUHMES neurons. Although neonicotinoids are considered to have low mammalian toxicity, emerging evidence suggests potential neurological impacts. The study focused on mitochondrial function, oxidative stress, neurite morphology, monoamine levels, and lipid metabolic alterations following clothianidin exposure. Thus far, exposure to clothianidin resulted in mitochondrial depolarization and a reduction in dopamine levels without overt cytotoxicity. Targeted lipidomic revealed significant alterations in lipid species involved in glycerophospholipid and sphingolipid metabolism, suggesting membrane remodeling and mitochondrial dysfunction. These findings indicate that lipid metabolic disturbances may be sensitive indicators of neonicotinoid-induced neurotoxicity, contributing to neuronal dysfunction. Further analyses are ongoing to clarify the mechanistic links between lipid perturbations and neurotoxic outcomes.

 

 

《Epidemiological studies of orthomarburgvirus infection in Egyptian Fruit bats in Ghana and Israel》

Kwadwo Boateng

 

 

Kwadwo presented epidemiological findings on orthomarburgvirus exposure in Egyptian fruit bats (Rousettus aegyptiacus) from Ghana and Israel, representing Marburg virus disease (MVD) endemic and non-endemic regions, respectively. Given the high fatality rate associated with Marburg virus infections in humans, understanding virus circulation in reservoir hosts is critical. The study involved serological and molecular screening of 70 wild-caught bats using ELISA, PCR, and Western blot analyses. Serological results demonstrated the presence of Marburg virus–specific antibodies in bats from both regions, with higher seroprevalence in Ghana compared to Israel, while PCR screening did not detect viral RNA in tissues. These findings confirm previous exposure of Egyptian fruit bats to Marburg virus beyond traditionally recognized endemic areas. The study highlights the importance of continued surveillance of filoviruses in bat populations to better understand spillover risks and prevent future outbreaks.

 

 

 《Development of reversible and non-invasive methods of reproductive suppression for population management in primates》

 Ryusuke Tsushima 

 

 

 In non-human primates, contraception is important for maintaining animal welfare and managing pedigrees. Synthetic progestins are commonly used in population control in these animals, however, long term exposure results in negative effects such as obesity. Therefore, alternative birth control methods such as GnRH vaccine, GnRH agonist and Zonna pellucida vaccine are being considered for population management. GnRH vaccines induce anti-GnRH antibodies that neutralize GnRH functions, while long-term release GnRH agonist implants downregulate pituitary GnRH receptors, suppressing the secretion of sex hormones. The pellucida (ZP) vaccines stimulate the immune system to produce anti-ZP antibodies, which bind to sperm-binding sites on the oocyte and block fertilization.

This study aims to verify the effects of GnRH control on reproductive suppression through contraceptive drug administration and evaluation of the usage/dosage and their efficacy. Further the study will develop a primate ZP vaccine using Japanese macaque zona pellucida protein as the antigen to promote a high-welfare reproductive suppression method.

By measuring sex hormone levels and antibody titers, and conducting behavioral observations, the study aims to establish minimally invasive and reversible reproductive suppression methods for primate population management.

 

 

《Gepotidacin as a promising treatment alternative against fluoroquinolone-resistant Salmonella Typhimurium infections》

Charlotte Poussier

 

 

 Non-typhoidal Salmonella (NTS) is a primary cause of acute gastroenteritis. Although typically mild and self-limiting, these infections can be life-threatening in vulnerable populations. Fluoroquinolones (FQs) are the first-line treatment for invasive NTS infections in adults, however, in the last decade, the rise of fluoroquinolone resistance has hindered the treatment of Salmonella infections, exacerbating the high fatality rates of invasive NTS diseases. Novel Gepotidacin is a new promising class of antimicrobial agents. While gepotidacin has completed phase 3 clinical studies for the treatment of uncomplicated urinary tract infection, its potential against FQs-resistant NTS isolates has yet to be explored.

The study compared the efficacy of gepotidacin to that of ciprofloxacin a Fluoroquinolones on wild-type and mutant Salmonella Typhimurium strains. IC50 values were used to compare the inhibitory effects of gepotidacin (GEP) and ciprofloxacin (CIP) against wild-type (WT) and mutant Salmonella Typhimurium DNA gyrases. The MICs of both drugs were evaluated against WT and mutant Salmonella Typhimurium using in vitro microbroth dilution assays. Mutant strains carrying the GyrA amino acid substitutions D87Y, G81C, and S83F were used. 

The comparative study showed that while GEP exhibits higher MIC values, the increase in MIC values from WT to mutant strains is strikingly lower compared to CIP suggesting that gepotidacin could be a promising alternative for treating invasive Salmonellosis caused by FQ-resistant NTS.