Journal of Veterinary Medical Science
Online ISSN : 1347-7439
Print ISSN : 0916-7250
ISSN-L : 0916-7250
Current issue
Displaying 1-18 of 18 articles from this issue
Anatomy
  • Tetsuhito KIGATA, Keiko MORIYA-ITO, Yoshiko HONDA
    2025 Volume 87 Issue 2 Pages 123-130
    Published: 2025
    Released on J-STAGE: February 01, 2025
    Advance online publication: December 16, 2024
    JOURNAL OPEN ACCESS

    The common marmoset (Callithrix jacchus) has attracted much attention as a nonhuman primate animal model for stress-related experiments. The adrenal gland plays a key role in stress responses and has abundant vasculature, through which the hypothalamic-pituitary axis hormonally controls its activity. Understanding the arterial supply pattern to the gland is fundamental to understanding its function and performing experiments. We therefore traced the arteries supplying the adrenal gland in six male and nine female common marmosets using the latex injection method. The adrenal artery originates from one to four parent arteries, including the caudal phrenic, celiac, left gastric, gonadal, and renal arteries and the abdominal aorta. The branching pattern of the adrenal arteries was divided into Types 1 to 4, having 1–4 parent arteries, respectively. Type 2 was most frequent on the right side (seven of 15 halves, 46%), whereas Type 3 was most frequent on the left (eight of 15 halves, 53%). The number of cranial, middle, and caudal adrenal arteries ranged from one to four in the cranial, one to five in the middle, and one to six in the caudal adrenal arteries. The total number of adrenal arteries varied from three to 13, predominantly as five on one side. The present study revealed frequent individual variations in the origin and number of adrenal arteries in the common marmoset, which may be informative for further research involving the adrenal glands in this species.

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  • Md SALAHUDDIN, Md AL-AMIN, Kohzy HIRAMATSU, Kazumi KITA
    2025 Volume 87 Issue 2 Pages 207-214
    Published: 2025
    Released on J-STAGE: February 15, 2025
    Advance online publication: December 25, 2024
    JOURNAL OPEN ACCESS

    This study aims to clarify influences of the short-term carbohydrate (CHO) restriction on plasma cells in chicken cecal tonsil (CT) using immunohistochemical and morphometrical techniques. Healthy male layer chickens were randomly divided into the control and three experimental groups. The three experimental groups were fed with diets containing 50%, 25%, and 0% CHO of that in the control diet, respectively. Following the experimental period for 7 days, CTs were collected from each chicken. Immunohistochemistry was performed to detect immunoglobulin (Ig) A, G and M. The density of IgA-immunoreactive cells was significantly lower in the lymphoid follicles (LFs) and diffuse lymphoid tissues (DLTs) in CTs of the 0% group compared to those of the other groups. There was a positive correlation between daily CHO intake and the density of IgA-immunoreactive cells in the DLTs and LFs. The density of IgM-immunoreactive cells was significantly decreased as daily CHO intake decreased, and there was a positive correlation between these two factors in both DLTs and LFs. The density of IgG-immunoreactive cells was significantly lower in DLTs of the 0% group than those in the control and 50% groups. The density of IgG-immunoreactive cells was significantly decreased with a decrease in daily CHO intake in DLT but not in LF. These findings demonstrated that dietary CHO had a significant effect on the density of plasma cells in the CTs exhibiting a declining trend with a decrease of ingested CHO volume.

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  • Shoichi WAKITANI, Risako KAWABATA, Sora SHIRATAKI, Masahiro YASUDA
    2025 Volume 87 Issue 2 Pages 131-134
    Published: 2025
    Released on J-STAGE: February 01, 2025
    Advance online publication: December 05, 2024
    JOURNAL OPEN ACCESS
    Supplementary material

    Immunohistochemistry for keratins 5, 8, 14, and 18 was performed on Japanese Black calf thymuses at various stages of acute thymic involution. Keratins 5 and 14 were predominantly localized in the thymic medulla, while keratins 8 and 18 were broadly distributed throughout the parenchyma. Despite thymic involution, the distribution patterns of these keratins remained consistent. The cortical area, assessed by keratin 5 staining, progressively decreased with involution but retained approximately 40% of the total parenchyma even at the most severe stage. These results suggest that the thymic cortex shrinks but does not completely disappear during acute thymic involution in calves.

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Avian Pathology
  • Takahiro INOUE, Keiko MIZUTANI, Hanako KUNISADA, Danielle LADZEKPO, Ko ...
    2025 Volume 87 Issue 2 Pages 215-222
    Published: 2025
    Released on J-STAGE: February 15, 2025
    Advance online publication: January 01, 2025
    JOURNAL OPEN ACCESS
    Supplementary material

    The poultry red mite (PRM), Dermanyssus gallinae, is a hematophagous ectoparasite that significantly threatens the poultry industry, not only through blood-feeding but also as a vector for deadly pathogens. With the growing challenge of acaricidal resistance, the demand for alternative control measures is urgent. However, effective PRM research, particularly in acaricidal efficacy and new drug discovery, hinges on the availability of reliable laboratory colonies. In this study, we successfully established a stable PRM laboratory colony, originally isolated from the field in 2021 and maintained under controlled conditions at the Research Institute for Animal Science in Biochemistry and Toxicology (RIAS). We investigated the growth kinetics and population dynamics of the laboratory colony within a Styrofoam-based maintenance box (SBMB) containing chicks. PRM propagation was tracked over 28 days, with mites collected every seven days. The average bulk weight of the mites in the trap increased from 4.3 ± 1.2 mg on day 7 to 201.4 ± 56.5 mg on day 28, despite seasonal variations, indicating optimal conditions for population growth. The collected mites spanned various blood-feeding developmental stages such as protonymph, deutonymph, and adult stages, enabling comprehensive assessments of molting and egg-laying efficiency. Our findings confirm that the laboratory colony of PRM can be stably maintained, providing a reliable source of PRMs for further experimental research aimed at advancing control strategies against this pervasive pest.

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Biochemistry
  • Yuuki HORII, Manami KURATA, Yuma YOSHIDA, Hiroki SAKAI, Takahiko SHIIN ...
    2025 Volume 87 Issue 2 Pages 160-166
    Published: 2025
    Released on J-STAGE: February 04, 2025
    Advance online publication: December 31, 2024
    JOURNAL OPEN ACCESS

    Hibernating animals show a remarkable decrease in body temperature without accompanying serious organ damage. Active hypometabolism may be involved in the protective mechanisms. Therefore, in the present study, the phosphorylation status of Akt was used to examine whether metabolism is actively reduced during artificial hypothermia in hamsters. Hypothermia induced by activation of the central adenosine A1 receptor (A1AR) resulted in dephosphorylation of Akt in the heart, as in that of hibernating hamsters. Since phosphorylated Akt almost totally disappeared, it is probable that cellular metabolism is actively reduced in A1AR-mediated hypothermia. Surprisingly, phosphorylation of Akt was significantly, but not totally, reduced even when hypothermia was induced by a combination of inhalation anesthesia and cooling. It can thus be considered that active regulation for the reduction of metabolic activity occurs in A1AR-mediated hypothermia as well as in anesthesia-induced hypothermia, though to a lesser extent. In both hypothermic conditions, serious arrhythmias were rarely observed. In anesthesia-induced hypothermia, during which dephosphorylation of Akt occurred only partially, there was no obvious organ damage in histopathological examination. Taken together, our findings suggest that artificial hypothermia causes active hypometabolism and has therapeutically applicable properties.

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Clinical Pathology
  • Daiki OKADA, Kazutaka KANAI, Yuya OTAKA, Tsubasa MATSUMOTO, Akane IZUM ...
    2025 Volume 87 Issue 2 Pages 223-231
    Published: 2025
    Released on J-STAGE: February 15, 2025
    Advance online publication: January 16, 2025
    JOURNAL OPEN ACCESS

    This study investigated the anti-inflammatory effects of water-dispersible hesperetin (WD-Hpt) in an endotoxin-induced uveitis (EIU) rat model. The rats were orally administered 10, 25, or 50 mg/kg WD-Hpt immediately after lipopolysaccharide (LPS) injection at the concentration of 200 μg. Clinical scores, cellular inflammation, the aqueous humor (ApH) protein concentration, as well as the levels of tumor necrosis factor (TNF)-α, cyclooxygenase (COX)-2 and inducible NO synthase (iNOS) in AqH, and histopathological grades were assessed. Immunohistostaining and mRNA analyses measured expressions of TNF-α, COX-2, iNOS, activated nuclear factor (NF)-κB p65, I kappa B (IκB)-α degradation, phosphorylated (p)-IκB kinase (IKK) α/β, β-catenin, and glycogen synthase kinase (GSK)-3β. Compared to LPS treated group (LPS txg), WD-Hpt treatment groups (WD-Hpt txg) resulted in the following results: 1) clinical scores improved [LPS txg; 3.90 ± 0.20, WD-Hpt txg; 2.40 ± 0.37 (P<0.05)], 2) the number of inflammatory cells in AqH decreased [LPS txg; 8.65 ± 1.41 × 105 cells/mL, WD-Hpt txg; 3.83 ± 1.20 × 105 cells/mL (P<0.05)], 3) AqH protein concentration reduced [LPS txg; 36.65 ± 2.71 mg/mL, WD-Hpt txg; 28.73 ± 2.36 mg/mL (P<0.05)], and 4) decreased levels of TNF-α [LPS txg; 69.55 ± 7.38 pg/mL, WD-Hpt txg; 35.18 ± 9.22 pg/mL (P<0.001)], iNOS [LPS txg; 153.37 ± 12.72 μM, WD-Hpt txg; 110.79 ± 13.27 μM (P<0.05)], and COX-2 [LPS txg; 1,080.56 ± 196.06 pg/mL, WD-Hpt txg; 477.80 ± 66.61 pg/mL (P<0.01)] in AqH were observed, and histopathological grades improved [LPS txg; 2.80 ± 0.40, WD-Hpt txg; 1.50 ± 0.50 (P<0.05)]. Immunostaining and mRNA analysis revealed that 50 mg/kg WD-Hpt effectively suppressed iNOS, COX-2, NF-κB p65, IκB-α degradation, p-IKKα/β, β-catenin, and GSK-3β expression. These findings suggested that WD-Hpt exerts anti-inflammatory effects by targeting the NF-κB and Wnt/β-catenin pathways.

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Internal Medicine
  • Honoka NOJO, Nobuo MURAYAMA, Sanae A ISHIJIMA, Rui KANO
    2025 Volume 87 Issue 2 Pages 135-137
    Published: 2025
    Released on J-STAGE: February 01, 2025
    Advance online publication: December 11, 2024
    JOURNAL OPEN ACCESS

    Canine Malassezia dermatitis (CMD) and otitis externa are generally treated by antifungal drugs. However, azole-resistant strains have been isolated from canine skin and ear canals worldwide. Phytochemicals isolated from essential oils are effective alternatives for inhibiting Malassezia pachydermatis. To evaluate the usefulness of phytochemicals against azole-resistant isolates, we performed in vitro susceptibility testing using the phytochemicals carvacrol, citral, and thymol. Eight antifungal-resistant isolates were obtained from 7 cases of dermatitis and 1 case of otitis externa during 2022 and 2023 from dogs in Tokyo and Kanagawa, Japan. Fungal susceptibility to carvacrol, citral, and thymol were assessed using the modified broth microdilution method. The minimum inhibitory concentrations (MICs) of the phytochemicals in all isolates were as follows: 0.03 to 0.125% for carvacrol; 0.03 to 0.125% for thymol; and 0.03% to 0.125% for citral. Based on these results, carvacrol, citral, and thymol appear to be effective against azole-resistant strains. The phytochemicals appear to be effective for treating antifungal-resistant cases of CMD and otitis externa.

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  • Hitomi SATO, Ren KUMANO, Rika FUKUMORI, Shin OIKAWA
    2025 Volume 87 Issue 2 Pages 167-170
    Published: 2025
    Released on J-STAGE: February 04, 2025
    Advance online publication: December 16, 2024
    JOURNAL OPEN ACCESS

    Calves experience a significant decrease in dietary lipid intake with weaning. However, changes in lipoprotein metabolism during this period has not been described. Therefore, to evaluate changes in lipoprotein metabolism by weaning and age, differences in lipoprotein lipid concentrations and proportions were compared before and after weaning and between calves and adult cows. Blood samples were collected from 27 Holstein calves before (4 weeks old) and after weaning (13 weeks old). Blood samples were also collected from 10 adult cows (5 dry and 5 lactating cows). As the results, total lipid concentrations (triglycerides + total cholesterol + phospholipids) in low-density lipoprotein (LDL) and high-density lipoprotein (HDL) were higher for pre-weaning calves than those in post-weaning calves. However, there were no differences in lipid proportions contained in each fraction. Lipid concentrations were higher in adult cows than in calves for all fractions: very low-density lipoprotein (VLDL), LDL and HDL. The proportion of total cholesterol and phospholipids in the LDL fraction was higher in calves compared to adult cows and the proportion of lipids in the HDL fraction was higher in adult cows compared to calves. These results showed that weaning caused litte changes in lipid concentrations in each lipoprotein fraction, but that adult cows showed higher lipid concentration in VLDL, LDL, and HDL. In addition, more lipids were contained in HDL for adult cows than in calves.

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  • Yasuhiko IKEDA, Taisuke KURODA, Hiroshi MITA, Norihisa TAMURA, Minoru ...
    2025 Volume 87 Issue 2 Pages 171-174
    Published: 2025
    Released on J-STAGE: February 04, 2025
    Advance online publication: January 14, 2025
    JOURNAL OPEN ACCESS
    Supplementary material

    We compared the antihistamine effect of four new antihistamines with olopatadine, which is used to treat equine allergic diseases. Six healthy Thoroughbred horses received oral doses of olopatadine (50 mg), levocetirizine (50 mg), bilastine (200 mg), rupatadine (100 mg), and desloratadine (50 mg) at >2-week intervals. The effects were investigated by measurement of the wheal area induced by histamine intradermal injection, and inhibition rate was compared with positive and negative controls. The maximum wheal inhibition rate (mean ± SD) of olopatadine (85.3% ± 7.7%) was significantly higher than those of bilastine (51.1% ± 11.8%), rupatadine (55.3% ± 6.6%), and desloratadine (59.8% ± 6.4%), but not levocetirizine (85.4% ± 8.0%). Levocetirizine is expected to have a high antihistamine effect on horses.

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Laboratory Animal Science
  • Chika OKI, Kinuko UNO, Tomohiko SASASE, Takahiro TSUTSUI, Keita SEKIGU ...
    2025 Volume 87 Issue 2 Pages 138-146
    Published: 2025
    Released on J-STAGE: February 01, 2025
    Advance online publication: December 11, 2024
    JOURNAL OPEN ACCESS

    Many genetic and environmental factors are involved in the development and progression of diabetic kidney disease (DKD), and its pathology shows various characteristics. Animal models of DKD play an important role in elucidating its pathogenesis and developing new therapies. In this study, we investigated the pathophysiological features of two DKD animal models: db/db mice (background of hyperglycemia) and KK-Ay mice (background of hyperinsulinemia). Male and female mice were fed a high-fat/high-sucrose (HFS) diet for eight weeks. Two mouse models fed the HFS diet showed increases in urinary protein, kidney weight, and glomerular size, but these changes were pronounced in KK-Ay mice. Pathological examination revealed tubulointerstitial fibrosis in KK-Ay mice fed the HFS diet, but not in db/db mice. In addition, fat accumulation was observed in the macula densa of db/db mice and in the glomeruli of KK-Ay mice fed with the HFS diet. In conclusion, an HFS diet exacerbates renal lesions with tubulointerstitial fibrosis in KK-Ay mice, and KK-Ay mice fed an HFS diet are expected to be useful as a DKD model.

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  • Natsuki AKASHI, Yui MIYAGAWA, Hiroaki KUNO, Masumi ETO, Tetsuya AKAGI
    2025 Volume 87 Issue 2 Pages 175-180
    Published: 2025
    Released on J-STAGE: February 04, 2025
    Advance online publication: December 31, 2024
    JOURNAL OPEN ACCESS

    Respiratory rate monitoring is essential especially for anesthetized animals in veterinary and biomedical research. Current methods often rely on invasive or wearable devices, which can stress animals, especially smaller ones like rodents. Here we present a non-invasive, environmentally integrated device that detects subtle breathing movements through waveform analyzed data via a triaxial accelerometer under a flexible fabric sheet in a trampoline-like box. The accuracy of the system was tested on anesthetized mice under varying isoflurane concentrations (1 to 3%) by comparison with a laser displacement sensor. The accelerometer data closely correlated with that from a laser displacement sensor, particularly under deeper anesthesia, with minimal deviations in respiratory rate detection. This method may provide a promising alternative for animal respiratory monitoring.

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Parasitology
  • Nami MATSUDA, Minori ITO, Yuka NUKADA, Miyuki TOYOMA, Kazuya NAGAI, To ...
    2025 Volume 87 Issue 2 Pages 181-188
    Published: 2025
    Released on J-STAGE: February 04, 2025
    Advance online publication: December 30, 2024
    JOURNAL OPEN ACCESS
    Supplementary material

    A comprehensive and quantitative method to compare gene expression may be useful for investigating the mechanisms responsible for diminazene aceturate (DA) resistance in Babesia gibsoni. Therefore, the gene expression of B. gibsoni cultured with DA was compared with those without DA using RNA sequencing (RNA-seq). Total RNA extracted from the parasites cultured with or without DA was examined using two next-generation sequencers, the 454 GS Junior and MiniSeq systems. We aimed to detect the genes differentially expressed between parasites cultured with and without DA by mapping the reads against de novo assembled contigs. The contigs, the amounts of which were more than five-fold higher in the parasite with DA than that without DA, were searched using BLAST®, and two contigs were found as parasite genes. Real-time quantitative reverse transcription-PCR (qRT-PCR) indicated that the expression levels of both genes were significantly higher in the parasites cultured with DA than those without DA. The nucleotide sequences of two contigs established using RNA-seq were similar to those found using direct sequencing, although the 5'- and 3'-end of those sequences were different between the two sequencing methods. In conclusion, we successfully utilized RNA-seq analysis to compare gene expression between parasites cultured with and without DA. RNA-seq can be used for comprehensive and quantitative analyses of gene expression in Babesia parasites.

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  • Toshihiro TOKIWA, Hisashi YOSHIMURA, Mami TAKASE, Eigo KATO, Masateru ...
    2025 Volume 87 Issue 2 Pages 147-151
    Published: 2025
    Released on J-STAGE: February 01, 2025
    Advance online publication: December 06, 2024
    JOURNAL OPEN ACCESS

    This report describes a case of disseminated proliferative mesocestoidosis in a French bulldog from Aichi, Japan. In July 2023, the dog presented with chronic enteritis, and histological examination of the endoscopic biopsy specimen revealed parasites with suckers. Three months later, numerous tetrathyridia were detected in the inguinal mass. In April 2024, polymorphic tetrathyridia were detected on the visceral organs. These parasites were identified as Mesocestoides vogae (Cyclophylidea: Mesocestoididae) based on morphological features and sequence analyses. In Japan, M. vogae has only been reported in domestic dogs, with five cases of intestinal infection and one case of abdominal infection. This report is the first case of both intestinal and extraintestinal infections in the westernmost region of Japan.

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  • Adrian Miki C MACALANDA, Eloiza May S GALON, John Carlo T HIPOLITO, Ni ...
    2025 Volume 87 Issue 2 Pages 189-193
    Published: 2025
    Released on J-STAGE: February 04, 2025
    Advance online publication: December 18, 2024
    JOURNAL OPEN ACCESS

    Parasitic diseases pose a threat to fisheries, negatively affecting the livelihood and food security of billions of people worldwide. Among these, parasitic isopods of fish are not well documented and studied. Thus, we examined the buccal cavity of 385 randomly selected saltwater fishes sold in a fish market in Naic, Cavite, Philippines. Here, 7/385 (1.82%) saltwater fishes, exclusively Trichiurus lepturus, harbored a parasitic isopod. Morphological observation and sequencing analysis of cytochrome c oxidase I (COI) and 16S rRNA genes confirmed the identity as Lobothorax typus. Phylogenetic tree based on these sequences showed that it is closely related to isolates from India and Japan. As such, further studies on the risk factors associated with L. typus infestation are urgently needed.

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Pathology
  • Takayuki MINESHIGE, Satoshi TAKAGI, Takanori SHIGA, Naoyuki AIHARA, Hi ...
    2025 Volume 87 Issue 2 Pages 194-197
    Published: 2025
    Released on J-STAGE: February 04, 2025
    Advance online publication: January 03, 2025
    JOURNAL OPEN ACCESS

    This report describes an atypical case of canine acanthomatous ameloblastoma (CAA) with mucinous glandular differentiation in a 12-year-old male Chihuahua with a right mandibular mass. Initially diagnosed as CAA by biopsy, computed tomography revealed bone lysis, prompting surgical excision. Histological examination showed lobular growth with two distinct neoplastic cell populations: typical CAA-like cells and a minor glandular structure population. Mucinous glandular differentiation in CAA is undocumented in veterinary literature. Immunohistochemistry showed positivity for cytokeratin AE1/AE3 in all tumor cells, and cytokeratin CAM5.2 and Alcian blue staining confirmed glandular cells and mucin. A low mitotic and K-i67 proliferation index suggested low-grade malignancy. This rare case highlights the need for comprehensive histopathological and immunohistochemical analysis to distinguish CAA from other oral tumors.

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Pharmacology
  • Yuta SHINOHARA, Mohamed ELBADAWY, Yishan LIU, Megumi YAMANAKA, Haru YA ...
    2025 Volume 87 Issue 2 Pages 232-240
    Published: 2025
    Released on J-STAGE: February 15, 2025
    Advance online publication: January 03, 2025
    JOURNAL OPEN ACCESS

    Muscle-invasive bladder cancer (MIBC) is a common form of BC in dogs. Adjuvant chemotherapy administration is commonly applied in MIBC cases, but patients sometimes experience treatment failure and recurrence. Therefore, supplements with anticancer properties, such as traditional Chinese medicines (TCMs), are required, and they have been widely used in Japanese human medicine and may be useful in veterinary medicine. Furthermore, organoid cultures can mimic the characteristics of their original tissues, such as self-renewal and organization. We previously established a novel experimental model for MIBC using a dog BC organoid (DBCO) culture. Herein, we examined the antiproliferative effects and mechanisms of 39 substances, consisting of TCMs, TCM supplements, and crude drug extracts, on DBCOs. Among the TCMs, D3 (also known as Shibe-ria), which is a mixture of chaga (Inonotus obliquus) and notoginseng (Panax notoginseng), significantly diminished the cell viability of DBCOs. The expression of BC stem cell markers, CD44 and SOX2, was reduced considerably in the D3-treated DBCOs. Among the components of D3, chaga exerted an antiproliferative effect on DBCO, whereas notoginseng did not. The administration of D3 also significantly reduced the volume of DBCO xenografted tumors in mice in vivo. Overall, D3 may have benefits as a natural anticancer supplement in veterinary medicine.

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Wildlife Science
  • Tadashi FUJII, Takashi KAMIO, Yuichiro AKUNE, Hideaki TAKAHASHI, Nobuh ...
    2025 Volume 87 Issue 2 Pages 152-159
    Published: 2025
    Released on J-STAGE: February 01, 2025
    Advance online publication: December 05, 2024
    JOURNAL OPEN ACCESS
    Supplementary material

    In recent years, an increased emphasis on enhancing the care and health management of captive marine mammals has been observed. Belugas (White Whale, Delphinapterus leucas), belonging to the family Monodontidae, are of considerable importance and often the centerpiece of aquarium collections worldwide. This study aimed to investigate the effects of the administration of prebiotics on the gut microbiota and overall health of the beluga. Prebiotic 1-kestose, a fructooligosaccharide comprising sucrose and fructose, was administered to three belugas, alongside their regular vitamin supplements for a duration of 8 weeks. 16S rRNA gene amplicon sequencing of intestinal DNA revealed that the relative abundance of the genus Turicibacter, a potentially pathogenic bacteria, significantly reduced after 1-kestose administration when compared to that at baseline (P=0.050). In addition, a quantitative PCR analysis revealed that the levels of collagenase gene, a putative virulence factor gene of Turicibacter, significantly reduced after 1-kestose administration (P=0.050). Blood creatinine levels that were initially above the normal value also reduced after 1-kestose administration (P=0.023). Therefore, this study demonstrated the potential of 1-kestose to improve the health and welfare of aquarium belugas.

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  • Ai ITO, Hideki ENDO
    2025 Volume 87 Issue 2 Pages 198-206
    Published: 2025
    Released on J-STAGE: February 04, 2025
    Advance online publication: December 26, 2024
    JOURNAL OPEN ACCESS

    The significance of forelimb morphology has been discussed with a focus on specific morphological aspects; nonetheless, the correlation of overall morphology, including various linear measurements, with respect to ecological preference and adaptation has not been extensively explored, particularly using multiple taxa. We investigated the morphological characteristics of the long bones in the forelimbs of mammalian species and their relationship with specific functional adaptations using 20 linear measurements and 22 terrestrial species from seven orders. Principal component analysis and canonical discriminant analysis showed that the lengths of the humerus, radius, and ulna as well as the distance from the smallest width to the proximal and distal ends, and the deltoid tuberosity length distinguished four adaptations: arboreal, terrestrial, fossorial, and semi-aquatic. Moreover, our findings indicate that the distance from the smallest width to the proximal and distal ends, the deltoid tuberosity length, and the breadth of the distal end of the humerus are crucial in differentiating semi-arboreal, aquatic, and fossorial species.

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