Biology subjects

Takai, M.

Publications and source records attributed to Takai, M..

4 recordsLinked to original sources

bioRxiv2026

Denisovan leg bones from Taiwan reveal large body size

Denisovans are an extinct archaic Homo group whose lineage diverged from the Neanderthal lineage approximately 550,000 years ago and were widely distributed across eastern Asia until [~]45,000 years ago1-7. Their morphological features are known directly from the existing cranio- dental and phalangeal remains1,2,8-12. However, the body size and postcranial morphology of the Denisovans remain largely unknown. We here report that hominin femoral and tibial fossils recovered from the Penghu Channel, Taiwan, are Denisovans in their proteomic profiles. Morphologically, these specimens are among the largest leg bones known in Pleistocene Homo. They exhibit generally archaic features, but also show some modern human-like morphology, including a strong femoral pilaster. Our findings demonstrate that the Denisovan population at the northern circle had larger body size than earlier Homo erectus as well as Late Pleistocene Homo sapiens in eastern Asia. This challenges the generally held expectation that Pleistocene Homo followed Bergmanns rule that anticipates latitudinal decline of body size, and suggests that the large Denisovan brain resulted from their large body size at least partly. The strong pilaster developed in the Penghu femur suggests some behavioral similarities between the Denisovans and the Upper Palaeolithic modern humans and/or gene flow from the latter to the former.

paleontology↗

bioRxiv2024

Odor sensory tests vs. In-silico prediction for the high-definition quantification of olfaction dynamics

The intricate dynamics of volatile organic compounds (VOCs) in the human respiratory system remain poorly understood. In the present study, we integrate odor sensory tests (OSTs) coupled with computational fluid dynamics and a physiologically based pharmacokinetic (CFD-PBPK) model to elucidate various aspects of the olfaction process. Safe yogurt-derived substances were incorporated in OSTs to prevent harmful exposure. Acetaldehyde was identified as a key active component in determining odor intensity, prompting further analysis of acetone and other four constituents of yogurt. Logarithmic correlations were established between the perceived odor intensity from the OSTs and both time-averaged absorption flux and equilibrium concentration within the olfactory mucus layer. These parameters were numerically captured, enabling the logarithmic approximation of odor intensity for different breathing profiles and the development of reliable prediction models for odor sensation based on quantifiable physiological parameters. The CFD-PBPK model captured detailed spatial and temporal variations of these parameters, which offers potential for future integrated/in-silico applications. Minor peaks of odor concentration were observed in the posterior olfactory regions during exhalation, revealing a retro-nasal phenomenon. Location-specific analysis revealed the nostrils and olfactory regions as the most accurate indicators of perceived odor intensity, proving the limitations of rough sensory assessments in the indoor/breathing zone scales. Acetone exhibited distinct absorption and desorption trends during the transitional phase between inhalation and exhalation, owing to the physical properties (diffusion and partition coefficients) that strongly characterize the olfaction dynamics. Author SummaryWe developed an integrated method using odor sensory tests (OSTs) coupled with computational fluid dynamics and physiologically based pharmacokinetic models (CFD-PBPK) to assess the temporal and spatial transport of yogurt odorants to the human olfactory region. Multiple phenomena were observed, including ortho-nasal and retro-nasal olfaction, temporal changes in the perceived odor intensity associated with breathing/sniffing profiles, absorption and desorption curves of acetone in the mucus epithelium, and regional-based olfaction distribution. The perceived odor intensity from OSTs can be predicted logarithmically in correlation with both the time-averaged absorption flux and the equilibrium concentration in the olfactory mucus layer, offering a reliable in-silico prediction model for odor sensation based on numerically quantifiable parameters. This model offers potential implications for multiple computational, biomedical, and industrial applications, such as the electric noses, smart odor sensors, food assessments, and fragrance development, particularly for long-term exposure in the industries that emit odorous compounds. It can open the door for more accurate predictions of the complex micro-fluid dynamics in the microbial ciliated tissues in the olfactory receptors.

bioengineering↗

bioRxiv2020

Dietary and body mass reconstruction of the Miocene neotropical bat Notonycteris magdalenensis (Phyllostomidae) from La Venta, Colombia

The middle Miocene La Venta bat fauna is the most diverse bat palaeocommunity in South America, with at least 14 species recorded. They include the oldest plant-visiting bat in the New World, and some of the earliest representatives of the extant families Phyllostomidae, Thyropteridae and Noctilionidae. La Ventas Notonycteris magdalenensis is an extinct member of the subfamily Phyllostominae, a group of modern Neotropical animalivorous and omnivorous bats, and is commonly included in studies of the evolution of Neotropical bats, but aspects of its biology remain unclear. In this study, we used a multivariate dental topography analysis (DTA) to reconstruct the likely diet of N. magdalenensis by quantitatively comparing measures of molar complexity with that of 25 modern phyllostomid and noctilionid species representing all major dietary habits in bats. We found clear differences in molar complexity between dietary guilds, indicating that DTA is potentially an informative tool to study bat ecomorphology. Our results suggest N. magdalenensis was probably an omnivore or insectivore, rather than a carnivore like its modern relatives Chrotopterus auritus and Vampryum spectrum. Also, we reconstructed the body mass of N. magdalenensis to be [~]50 g, which is larger than most insectivorous bats, but smaller than most carnivorous bats. Our results confirm that Notonycteris magdalenensis was probably not a specialised carnivore. It remains to be demonstrated that the specialised carnivory ecological niche was occupied by the same lineage of phyllostomines from at least the middle Miocene. Combining our diet and body mass reconstructions, we suggest that N. magdalenensis exhibits morphological pre-adaptations crucial for the evolution of specialised carnivory.

paleontology↗

bioRxiv2019

Unique Cancer Motility Behaviors in Confined Spaces of Microgroove Topography with Acute Wall Angles

In recent years, many types of micro-engineered platform have been fabricated to investigate the influences of surrounding microenvironments on cell migration. Previous researches demonstrate that microgroove-based topographies can influence cell motilities of normal and cancerous cells differently. In this paper, the microgroove wall angle is altered from obtuse to acute angles and the resulting differences in the responses of normal and cancer cells are investigated to explore the geometrical characteristics that can efficiently distinguish normal and cancer cells. Interestingly, trends in cell motilities of normal and cancer cells as the wall angles are varied between 60-120{degrees} were different, and in particular, invasive cancer cells exhibit a unique, oscillatory migratory behavior. Results from the immunostaining of cell mechanotransduction components suggest that this difference stems from directional extension and adhesion behaviors of each cell type. In addition, the specific behaviors of invasive cancer cells are found to be dependent on the myosin II activity, and modulating the activity can revert cancerous behaviors to normal ones. These novel findings on the interactions of acute angle walls and cancer cell migration provide a new perspective on cancer metastasis and additional strategies via microstructure geometries for the manipulations of cell behaviors in microscale biodevices.\n\nStatement of SignificanceCancer metastasis is the leading cause of cancer patient deaths, and yet how the microstructures within the body affect this cell migration phenomenon is not well understood. In this paper, microdevices containing microgroove structures of varying geometries, in particular obtuse and acute angles, were utilized to monitor cell motilities of various cancer cells to understand the influences of the geometrical features of microstructures on cancer metastasis. Surprisingly, it was found that the acute angle geometries lowered the persistence of migration for cancer cells, which was a totally different response from non-cancerous cells. These new findings would enable the next-generation biodevices to analyze, separate and capture cancer cells, as well as shed light onto the underlying mechanisms of cancer metastasis.

cancer biology↗