麻布大学

Urbanization influences not only free-living organisms, but also various pathogens, including those with limited visibility to humans. Although previous research on urban parasites has primarily focused on human-specific and zoonotic species, a comprehensive understanding of parasite ecology in urban settings requires attention to inconspicuous enzootic species. In this study, we investigated two flea species, Aenigmopsylla grodekovi and Ceratophyllus (Monopsyllus) indages indages, parasitizing Eurasian red squirrels Sciurus vulgaris orientis in and around Obihiro City, Hokkaido, Japan. These fleas, dislodged during the routine handling of host squirrels, were collected and quantified during spring and autumn surveys to assess seasonal and spatial patterns of infestation across urban and rural sites. Over the course of a four-year survey (2017–2020), 317 squirrels (168 males and 149 females) were examined, with 284 individuals of A. grodekovi and 214 of C. (M.) indages indages recovered. The former was rarely observed in spring but showed a pronounced increase in autumn, with rural areas exhibiting 14.06 times more dislodged individuals than urban areas, on average. In contrast, the latter was more prevalent in spring (2.50 times higher than in autumn) and displayed no consistent difference between urban and rural habitats. Our results revealed distinct dislodgement patterns in two flea species in response to habitat and seasonal variations, indicating species-specific responses to urbanization. While direct quantification of flea abundance remains ideal, the number of dislodged individuals may serve as a useful indicator for assessing the effect of urbanization on host-parasitic interactions and infrapopulation dynamics.

Brachial plexus morphology varies among species and is useful to understand forelimb phylogeny. Classifications of the Japanese raccoon dog and common raccoon dog (Nyctereutes procyonoides) are under discussion, and comparisons of brachial plexus morphology between them may provide clues to address this issue. However, brachial plexus morphology has not been investigated in Japanese raccoon dogs. Twenty brachial plexuses from 11 Japanese raccoon dogs were observed macroscopically, and the epineurium was then incised under surgical microscopy to trace the fascicles. The roots of brachial plexuses comprised ventral branches from the 6th-8th cervical nerves (C6-8) to the 1st thoracic nerve in 12 plexuses or to the 2nd thoracic nerve in eight plexuses. Macroscopically, nerves arising from the brachial plexus showed frequent variations. By fasciculus analysis, fasciculus components showed less variations than suggested macroscopically and most nerves showed the typical pattern (i.e., detected in more than 50% of halves), except for the caudal pectoral nerve. Moreover, patterns of communication among terminal branches, such as the axillary, radial, musculocutaneous, median and ulnar nerves, were analysed. Most frequently, we detected that the communicating branch between the axillary and radial nerves included fasciculi from C6 and C7 to the radial nerve, and that between the musculocutaneous and median nerves included a fasciculus from C8 to the musculocutaneous nerve. The details of brachial plexus morphology in Japanese raccoon dogs may provide an anatomical basis for comparing brachial plexus morphology between species.

Volatile organic compounds (VOCs) are increasingly implicated in systemic diseases, but their contribution to skin disorders such as atopic dermatitis (AD) remains unclear. This study assessed VOC concentrations in medical environments, their effects on AD development, and the efficacy of VOC removal using chemical filters. Total VOC levels were monitored in 3 types of veterinary hospitals. AD-like lesions were induced in female NC/Nga mice by repeated dermal application of toluene diisocyanate or house dust mite ointment, with or without topical exposure to a VOC mixture (10 μg/ml). Clinical parameters, including dermatitis scores, transepidermal water loss, and skin thickness, were measured weekly, and immunological and histological analyses were performed. VOC monitoring revealed that 1 hospital exhibited concentrations exceeding 400 μg/m³. In the mouse model, direct VOC exposure significantly aggravated keratinocyte inflammation and worsened AD symptoms. Application of chemical filtering systems effectively reduced VOC levels in real clinical settings, and their use in the experimental model suppressed AD development. However, therapeutic application of VOC removal showed only limited effects on systemic immunological markers. These findings suggest that VOCs present in healthcare environments may contribute to the onset and progression of AD. Incorporating VOC-removing filters into air-conditioning systems could serve as a preventive strategy to improve the management of allergic skin diseases.

PURPOSE. The SIX6 gene is a major susceptibility gene for human glaucoma, and its variants have been implicated in structural and functional alterations of the retina, such as nerve fiber layer thinning and retinal ganglion cell degeneration, which contribute to glaucoma development. This study investigated whether SIX6 polymorphisms are associated with glaucoma in dogs, focusing on the Shiba-Inu and Shih-Tzu breeds. METHODS. We genotyped 19 single nucleotide polymorphisms within the SIX6 gene region in 109 Shiba-Inus (49 cases and 60 controls) and 57 Shih-Tzus (18 cases and 39 controls), followed by association analyses. Comparative sequence analysis of canine and human SIX6 was performed to assess evolutionary conservation. RESULTS. In Shiba-Inus, rs851962234, located in the 3'-untranslated region of SIX6, was significantly associated with glaucoma (P = 0.0047; Pc = 0.038), with the minor A allele showing a frequency of 17.3% in cases and 4.2% in controls, and conferring an increased risk (odds ratio, 3.56). In contrast, rs851962234 showed no association in ShihTzus, likely owing to the rarity of the A allele in this breed. No other single nucleotide polymorphisms were associated with glaucoma in either breed. A comparative analysis showed a 98.4% amino acid identity between canine and human SIX6 across the coding regions. CONCLUSIONS. This study identifies rs851962234 in canine SIX6 as being significantly associated with glaucoma in Shiba-Inus, suggesting its potential role in modulating SIX6 expression and retinal ganglion cell vulnerability. These findings offer new insight into the genetic basis of canine glaucoma and highlight parallels and distinctions with human disease.

High-voltage electrostatic fields (HVEF) have been demonstrated to effectively maintain the quality and freshness of fruits, vegetables, and aquatic products during storage. To investigate the effects of HVEF on the microbial growth and meat quality characteristics, pork semimembranosus muscles were treated with HVEF under 0, -90, -150, +90, and +150 kV/m for 72 h at 4 degrees C. The results showed that the total plate counts in pork samples were significantly reduced by HVEF treatments (p < 0.05), with the positive HVEF treatment demonstrating the greatest efficacy in inhibiting bacterial growth. HVEF treatments also significantly improved the water-holding capacity of the samples, while reducing both drip loss and cooking loss. Among the treatment groups, negative HVEF effectively maintained protein integrity, inhibited lipid oxidation, and preserved muscle microstructure during storage. In contrast, positive HVEF led to more pronounced tissue damage, particularly at higher voltage intensities. Finally, this study showed that positive HVEF induced tissue disruption and myofibril fragmentation, thereby promoting tenderization, and exhibits strong potential for application in improving pork processing quality.