Biology subjects

Seki, F.

Publications and source records attributed to Seki, F..

5 recordsLinked to original sources

bioRxiv2025

Evolutionary and structural basis of SLAM utilization in morbilliviruses - Its implications for host range and cross-species transmission

Morbilliviruses, including measles virus (MV), canine distemper virus (CDV), and cetacean morbillivirus, pose a significant threat to humans and animals. While the host range of morbilliviruses is generally well-defined, severe cross-species transmission events also have been reported. Their entry into immune cells, the primary targets of morbilliviruses, relies on the signaling lymphocytic activation molecule (SLAM), a receptor whose species-specific variations influence viral host range. However, the extent to which SLAM diversity is a barrier to cross-species transmission remains poorly understood. In this study, we systematically investigated SLAM-mediated host specificity. We found that most morbilliviruses efficiently utilize SLAM from multiple host species, except for human SLAM. Among the morbilliviruses tested, only MV efficiently utilized human SLAM. Bats are natural reservoirs for many zoonotic viruses. Recent discoveries of novel morbilliviruses in bats provide new insights into morbillivirus evolution. Bats may have played a significant role in morbillivirus evolution because bat (Myotis) SLAM also functioned as an efficient receptor for multiple morbilliviruses. Unlike other morbilliviruses, MV utilized Myotis bat SLAM inefficiently. We conducted an MV adaptation experiment with Myotis bat SLAM to better understand SLAM recognition by morbilliviruses. MV readily adapted to utilize Myotis bat SLAM by acquiring a single N187Y mutation in its hemagglutinin protein, and computational structural modeling and fragment molecular orbital calculations with molecular dynamics simulations revealed key interaction changes that facilitated MVs adaptation to Myotis bat SLAM. These findings highlight the adaptability of morbilliviruses in utilizing diverse animal SLAMs. Notably, hypothetical ancestral SLAMs reconstructed in this study acted as universal receptors for all morbilliviruses. These results reinforced that morbillivirus receptor usage is primarily supported by evolutionarily conserved structural features of SLAM, highlighting a molecular basis that enables morbilliviruses to rapidly adapt to diverse animal SLAMs. Author SummaryOur study explores how viruses in the genus morbillivirus, such as measles virus, canine distemper virus, and rinderpest virus, which are notorious for deadly outbreaks in humans and animals, can jump between species. The host range of morbilliviruses is significantly influenced by a receptor molecule on cell surfaces known as the signaling lymphocytic activating molecule (SLAM). By examining SLAMs from various animals, including humans, dolphins, dogs, seals, and bats, we observed how these viruses can infect or adapt to infect different hosts. We found that in some cases slight differences in SLAM may act as initial barriers to cross-species transmission. However, these viruses rapidly overcome such barriers, showing a remarkable ability to adapt. Our research highlights the importance of monitoring these viruses to predict and prevent potential cross-species infections, which is crucial for protecting public health and animal welfare over time.

microbiology↗

bioRxiv2024

Development of a noninvasive olfactory stimulation fMRI system in marmosets

Olfactory dysfunction is associated with aging and the earliest stages of neurodegenerative diseases, such as Alzheimers and Parkinsons diseases; it is thought to be an early biomarker of cognitive decline. In marmosets, a small non-human primate model used in brain research, olfactory pathway activity during olfactory stimulation has not been well studied because of the difficulty in clearly switching olfactory stimuli inside a narrow MRI. Here, we developed an olfactory-stimulated fMRI system using a small-aperture MRI machine. The olfactory presentation system consisted of two tubes, one for supply and one for suction of olfactory stimulants and a balloon valve. A balloon valve installed in the air supply tube controlled the presentation of the olfactory stimulant, which enabled sharp olfactory stimulation within MRI, such as 30 seconds of stimulation repeated five times at five-minute intervals. The olfactory stimulation system was validated in vivo and in a simulated system. fMRI analysis showed a rapid increase in signal values within 30 s of olfactory stimulation in eight regions related to the sense of smell. As these regions include those associated with Alzheimers and Parkinsons diseases, olfactory stimulation fMRI may be useful in clarifying the relationship between olfactory dysfunction and dementia in non-human primates.

physiology↗

bioRxiv2023

Development of a non-invasive novel individual marmoset holder for evaluation by awake functional magnetic resonance brain imaging

BackgroundAlthough functional MRI (fMRI) in awake marmosets (Callithrix jacchus) is fascinating for functional brain mapping and evaluation of brain disease models, it is difficult to launch awake fMRI on scanners with less than 15 cm of bore size. A universal marmoset holder for the small-bore size MRI was designed, and evaluated whether this holder could conduct auditory stimulation fMRI in the awake state. New MethodThe marmoset holder was designed with an outer diameter of 71.9 mm. A holder was designed to allow adjustment according to the individual head shape, enabling to use the holder universally. An awake fMRI study of auditory response was conducted to evaluate the practicality of the new holder. Whole-brain activation was investigated when marmosets heard the marmoset social communication "phee call," an artificial tone sound, music (bossa nova), and reversed of those. ResultsThe prefrontal cortex was significantly activated in response to phee calls, whereas only the auditory cortex was activated in response to pure tones. In response to bossa nova, the marmosets visual and auditory cortices were activated. In contrast, the auditory response was decreased when marmosets heard phee calls and bossa nova music played backward. Their stimulus-specific responses indicated they perceived and differentiated sound characteristics in the fMRI environment. Comparison with Existing MethodsA holder does not require surgical intervention or custom-made helmet to minimize head movement in small space. ConclusionOur newly developed holder made it possible to perform longitudinal fMRI experiments on multiple marmosets in a less invasive manner. HighlightO_LIWe designed a universal marmoset holder for the optimization of small-bore size MRI. We aimed to evaluate whether the data acquired by fMRI with this holder indicated that awake marmosets were likely to recognize sounds during fMRI and whether the brain activity shown as fMRI signals reflected the characteristics of each sound. C_LIO_LIAfter the acclimatization of the marmosets to the holder, an awake fMRI study was conducted to evaluate the practicality of the new holder and successfully acquired the auditory responses to the set of sound stimuli. C_LIO_LIOur newly developed holder does not require surgical intervention to minimize head movement, which allows for less invasive fMRI experiments and makes it easier to conduct longitudinal fMRI for multiple marmosets. C_LI

neuroscience↗

bioRxiv2022

A novel micro-ECoG recording method for recording multisensory neural activity from the parietal to temporal cortexes in mice

Characterization of inter-regional interactions in brain is essential for understanding the mechanism relevant to normal brain function and neurological disease. The recently developed flexible micro ()-electrocorticography (ECoG) device is one prominent method used to examine large-scale cortical activity across multiple regions. The sheet-shaped ECoG electrodes arrays can be placed on a relatively wide area of cortical surface beneath the skull by inserting the device into the space between skull and brain. Although rats and mice are useful tools for neuroscience, current ECoG recording methods in these animals are limited to the parietal region of cerebral cortex. Recording cortical activity from the temporal region of cortex in mice has proven difficult because of surgical barriers created by the skull and surrounding temporalis muscle anatomy. Here, we developed a sheet-shaped 64-channel ECoG device that allows access to the mouse temporal cortex, and we determined the factor determining the appropriate bending stiffness for the ECoG electrode array. We also established a surgical technique to implant the electrode arrays into the epidural space over a wide area of cerebral cortex covering from the barrel field to olfactory (piriform) cortex, which is the deepest region of the cerebral cortex. Using histology and computed tomography (CT) images, we confirmed that the tip of the ECoG device reached to the most ventral part of cerebral cortex without causing noticeable damage to the brain surface. Moreover, the device simultaneously recorded somatosensory and odor stimulus-evoked neural activity from dorsal and ventral parts of cerebral cortex in awake and anesthetized mice. These data indicate that our ECoG device and surgical techniques enable the recording of large-scale cortical activity from the parietal to temporal cortex in mice, including somatosensory and olfactory cortices. This system will provide more opportunities for the investigation of physiological functions from wider areas of the mouse cerebral cortex than those currently available with existing ECoG techniques.

neuroscience↗

bioRxiv2022

Multi-modal brain magnetic resonance imaging database covering marmosets with a wide age range

Magnetic resonance imaging (MRI) is a noninvasive neuroimaging method beneficial for the identification of normal developmental and aging processes and data sharing. Marmosets have a relatively shorter life expectancy (approximately 10 years) than other primates, including, humans because they grow and age faster. Hence, the common marmoset model is effective in aging research. The current study investigated the aging process of the marmoset brain and provided an open MRI database on marmosets with a wide age range. The Brain/MINDS Marmoset Brain MRI Dataset contains brain MRI information on 216 marmosets aged between 1 and 10 years. During its release date, it is the largest public dataset worldwide. Further, it comprises multi contrast MRI images. In addition, 91 of 216 animals have corresponding ex vivo high-resolution MRI datasets. Our MRI database, which is available at the Brain/MINDS Data portal might help understand the effects of different factors, such as age, sex, body size, and fixation, on the brain. Moreover, it can contribute to and accelerate brain science studies worldwide.

neuroscience↗