Biology subjects

Sawamoto, K.

Publications and source records attributed to Sawamoto, K..

3 recordsLinked to original sources

bioRxiv2024

Neuronal migration depends on blood flow in the adult brain

In animal tissues, several cell types migrate along blood vessels, raising the possibility that blood flow influences cell migration. Here, we show that blood flow promotes the migration of new olfactory-bulb neurons in the adult brain. Neuronal migration is facilitated by blood flow, leading to accumulation of new neurons near blood vessels with abundant blood flow. Blood flow inhibition attenuates blood vessel-guided neuronal migration, suggesting that blood contains factors beneficial to neuronal migration. We found that ghrelin, which is increased in blood by hunger, directly influences neuronal migration. Ghrelin signaling promotes somal translocation by activating actin cytoskeleton contraction at the rear of the cell soma. New neurons mature in the olfactory bulb and contribute to the olfactory function for sensing odorants from food. Finally, we show that neuronal migration is increased by calorie restriction, and that ghrelin signaling is involved in the process. This study suggests that blood flow promotes neuronal migration through blood-derived ghrelin signaling in the adult brain, which could be one of the mechanisms that improves the olfactory function for food-seeking behavior during starvation.

neuroscience↗

bioRxiv2022

Seg2Link: an efficient and versatile solution for semi-automatic cell segmentation in 3D image stacks

Recent advances in microscopy techniques, especially in electron microscopy, are transforming biomedical studies by acquiring large quantities of high-precision 3D cell image stacks. However, to study cell morphology and connectivity in organs such as brains, scientists must first perform cell segmentation, which involves extracting individual cell regions of various shapes and sizes from a 3D image. This remains a great challenge because automatic cell segmentation can contain numerous errors, even with advanced deep learning methods. For biomedical research that requires cell segmentation in large 3D image stacks, an efficient semi-automated software solution is still needed. We created Seg2Link, which generates automatic segmentations based on deep learning predictions and allows users to quickly correct errors in the segmentation results. It can perform automatic instance segmentation of 2D cells in each slice, 3D cell linking across slices, and various manual corrections, in order to efficiently transform inaccurate deep learning predictions into accurate segmentation results. Seg2Links data structure and algorithms were also optimized to process 3D images with billions of voxels on a personal computer quickly. Thus, Seg2Link offers a simple and effective way for scientists to study cell morphology and connectivity in 3D image stacks.

neuroscience↗

bioRxiv2021

Change in the bladder function of rats with focal cerebral infarction induced by photochemically-induced thrombosis

The photochemically-induced thrombosis(photothrombosis) method can create focal cerebral infarcts anywhere in the relatively superficial layers of the cerebrum; it is easy to implement and minimally invasive. Taking advantage of this versatility, we aimed to establish a new rat model of urinary frequency with focal cerebral infarction, which was characterized by its simplicity, nonlethal nature, and high reproducibility. The prefrontal cortex and the anterior cingulate cortex, which are urinary centers, were targeted for focal cerebral infarction, and urinary parameters were measured by cystometrogram. Cystometric analysis indicated that micturition intervals significantly shortened in photothrombosis-treated rats compared with those in the sham operative group on Days 1 and 7 (P < 0.01), but prolonged after 14 days, with no difference between the two groups. Immunopathological evaluation showed an accumulation of activated microglia, followed by an increase in reactive astrocytes at the peri-infarct zone after photothrombotic stroke. Throughout this study, all postphotothrombosis rats showed cerebral infarction in the prefrontal cortex and anterior cingulate cortex; there were no cases of rats with fatal cerebral infarction. This model corresponded to the clinical presentation, in that the micturition status changed after stroke. In conclusion, this novel model combining nonlethality and high reproducibility may be a suitable model of urinary frequency after focal cerebral infarction.

physiology↗