What does the hantavirus do inside its rodent hosts? How does it move through animal populations? And why does it cause almost no symptoms in rodents, yet can be nearly fatal in humans?

For more than 35 years, Specially Appointed Professor Hiroaki Kariwa at Hokkaido University has explored these questions. His team has uncovered key insights into hantavirus ecology and evolution, including the discovery of the Hokkaido virus.

Organic molecular crystals can respond to external stimuli such as heat, light, and mechanical force, making them attractive candidates for next-generation functional materials. However, predicting how multiple intermolecular interactions cooperate or compete to govern crystal behavior remains a major challenge. Now, researchers at Kochi University of Technology have demonstrated that the hierarchy of intermolecular interactions—the relative strength and priority of different molecular forces—can determine crystal structures, luminescence properties, and even phase-transition pathways in molecular crystals. Their findings provide a new design principle for controlling solid-state functions through molecular engineering. The study was conducted by Mahiro Nakabayashi and Professor Shotaro Hayashi and published in Angewandte Chemie International Edition.

Movements to restrict immigration are picking up steam in the US, itself a nation of immigrants. Based on its “America First” ideology, the second Trump administration, which began in 2025, has proposed a series of hardline policies, such as limiting the acceptance of refugees and mass deportation of undocumented immigrants. As antiforeign movements continue to build strength, trends in municipalities called “sanctuary cities,” which are tolerant to undocumented immigrants, are also gathering attention. We sat down with Graduate School of Intercultural Studies Professor YASUOKA Masaharu, an expert on US immigration policy, to hear more about Trump administration policies and the current state of sanctuary cities.

Researchers led by Kaoru Sugimura from the University of Tokyo have identified the mechanism that ensures average cell size is constant across samples of developing Drosophila melanogaster (fruit fly) wings. They have found that rather than every cell behaving in the same way, several distinct groups of cells that differ in when and how many times they divide work together to reproduce the average cell size with remarkable precision. This new framework for understanding how developing animal tissues control cell size could widen avenues for research into conditions associated with abnormal cell size, such as cardiac hypertrophy and cancer. The findings were published in the journal Development.

Mother-to-infant bonding difficulties (MIBD) are commonly associated with postnatal depression. MIBD has been linked to developmental delays and child abuse. Researchers found that about half of MIBD cases in Japan involve mothers who did not experience postpartum depression. Difficulty holding a fussy baby, lack of happiness about pregnancy, and low social support predict an increased risk of MIBD. Clinicians observing these signs should intervene to ensure maternal and child well-being.

Scientists have developed a hierarchical Transformer-based artificial intelligence model that predicts RNA splice sites across DNA sequences up to 100,000 base pairs long while preserving single-nucleotide resolution. The system captures long-range regulatory interactions that conventional approaches often miss and visualizes the sequence regions influencing its predictions. The approach achieved state-of-the-art performance on multiple benchmark datasets and may support future studies in genetic diseases, cancer, precision medicine, genomic medicine, and therapeutic development.

Although lung cancer is often linked to environmental exposures and acquired mutations, some patients develop multiple independent tumors, suggesting a potential role for inherited genetic susceptibility. While the contribution of germline pathogenic variants (GPVs) in several tumors is studied, their significance in lung cancer remains unknown. Now, researchers have explored the genetic basis of multiple primary lung cancers, offering  insights into novel BRCA2 GPVs which could serve as targets for therapeutic strategies.

Cricket mothers transmit environmental information that determines embryonic developmental timing. Researchers have demonstrated that entry into developmental arrest is controlled by an integrated program of transcriptional, epigenetic, and metabolic reprogramming. Their study uncovers a system-level mechanism linking environmental cues to embryonic fate.

Two-wheeled vehicles naturally lean during turns, making it challenging for rider-assistance systems to tell if the rider is making a planned turn or losing balance. In a recent study, scientists from Shibaura Institute of Technology in Japan created a machine-learning-based steer-by-wire bicycle that can differentiate between these situations. This innovation could make electric bicycles and motorcycles safer without disrupting the riders’ intended movements.