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    25 June 2025, Volume 45 Issue 3
    Animal Models of Human Diseases
    Dynamic Evaluation of Vinorelbine-Induced Phlebitis of Dorsalis Pedis Vein in a Rat Model
    JIANG Meng, HAO Shulan, TONG Liguo, ZHONG Qiming, GAO Zhenfei, WANG Yonghui, WANG Xixing, JI Haijie
    2025, 45(3):  251-258.  DOI: 10.12300/j.issn.1674-5817.2024.163
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    Objective To dynamically observe the clinical symptoms and pathological changes in a rat model of vinorelbine-induced phlebitis via injection into the dorsalis pedis vein. Methods Twenty-eight 11-week-old male SPF-grade SD rats were randomly divided into a model group (n=20) and a control group (n=8). The model group received a single injection of 0.1 mL vinorelbine solution (4 mg/mL) via the right hind limb dorsalis pedis vein, while the control group received an equal volume of normal saline via the same method. The occurrence and grading of phlebitis in both groups were observed and recorded daily. The volume of the injured limb was measured by the drainage method to calculate the swelling rate. The weight-bearing ratio of the injured limb was assessed using a bipedal balance pain meter, and the skin temperature of the injured limb was measured by infrared thermal imaging. These measurements were conducted for 9 consecutive days. Starting from day 1, three rats from the model group were euthanized every other day. A 1-cm segment of the vein extending proximally from the injection site was collected. Pathological changes in the vein tissue were examined by hematoxylin-eosin staining, and ultrastructural changes of the vascular endothelium were observed using scanning electron microscopy. Results Compared to the control group, the injected hindlimb of model rats showed redness and swelling on day 1, with the swelling rate peaking at (81.89±15.75) % on day 3 (P<0.001), then gradually alleviating and decreasing to (15.41±0.33) % by day 9 (P<0.01). Pain was observed in the affected limbs of model rats on day 1 and worsened markedly on day 3, with the weight-bearing ratio decreasing to (36.35±4.91)% (P<0.001). Meanwhile, the skin temperature of the lesion site increased, reaching (36.36±0.40) ℃ on day 5 (P<0.001). Both pain and fever returned to near normal levels by day 9. Phlebitis grading in the model group showed that 75.0% of rats were grade Ⅱ on day 1; grade Ⅲ and Ⅳ each accounted for 37.5% on day 3; from days 5 to 9, most rats exhibited cord-like veins, predominantly grade III. Venous tissue showed peripheral edema and inflammatory cell infiltration on day 1, which gradually progressed to intimal rupture, vessel wall thickening, and even lumen narrowing from day 3 to 9. The venous intima exhibited destruction of tight junctions between endothelial cells and adhesion of blood cells, progressing to roughened, wrinkled, and protruding intimal surfaces. Conclusion The vinorelbine-induced phlebitis of dorsal foot vein in rat model is characterized by local redness, swelling, warmth, and pain from days 3 to 5, which largely resolve by day 9, although cord-like veins can still be observed. With disease progression, venous tissue develops edema, vessel wall thickening, and lumen narrowing. The venous intima shows rupture, roughening, and in some cases, complete loss.

    Cartilage Protection and Anti-Inflammatory Effects of Fraxetin on Monosodium Iodoacetate-Induced Rat Model of Osteoarthritis
    LIU Zhiwei, YANG Ran, LIAN Hao, ZHANG Yu, JIN Lilun
    2025, 45(3):  259-268.  DOI: 10.12300/j.issn.1674-5817.2024.165
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    Objective To establish a rat model of osteoarthritis and study the anti-inflammatory effects and mechanisms of fraxetin. Methods Eighteen 8-week-old male SPF-grade SD rats were randomly divided into three groups: Rats in the blank group received a right articular cavity injection of 50 μL of normal saline for 1 week; the model and intervention groups were injected with monosodium iodoacetate (MIA) into the right joint cavity to induce osteoarthritis, while the intervention group subsequently received fraxetin (5 mg·kg-1·d-1) for 1 week. Four weeks after drug intervention, abdominal aortic blood was collected. The animals were then euthanized, and knee joint cartilage were collected. The cartilage samples were stained with hematoxylin-eosin, safranin O-fast green, and toluidine blue for histopathological examination and scoring using the Mankin and OARSI scoring systems. The trabecular bone volume/total volume (Tb.BV/TV), trabecular bone surface density/total volume (Tb.BS/TV), and trabecular number (Tb.N) of each group were compared and analyzed using a micro-CT scanning system. The expression levels of various inflammatory factors [tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6)], and cartilage oligomeric matrix protein (COMP) were measured using enzyme-linked immunosorbent assay (ELISA). The expression levels of mitogen-activated protein kinase p38 (p38 MAPK), phosphorylation-p38 MAPK (p-p38 MAPK), c-Jun N-terminal kinase (JNK), and phosphorylation-JNK (p-JNK) were measured by western blotting. Results The staining of cartilage sections of rat knee joints showed that the articular surface defects in the model group were severe, while the cartilage destruction in the intervention group was relatively reduced. Micro-CT results showed that Tb.BV/TV, Tb.BS/TV and Tb.N in the intervention group were significantly higher than those in the model group (P < 0.05); the Mankin score in the model group was significantly higher than that in the blank group (P < 0.05), the Mankin score in the intervention group was significantly lower than that in the model group (P < 0.05); while the OARSI score in the intervention group was significantly lower than that in the model group (P < 0.05). The results of the enzyme-linked immunosorbent assay showed that the serum levels of TNF-α, IL-1β, IL-6, and COMP in the model group were significantly higher than those in the blank group (all P < 0.05), while those in the intervention group were significantly lower than in the model group (P < 0.05). Western blot results showed that the expression levels of p-p38 MAPK and p-JNK in the knee cartilage tissue were significantly lower in the intervention group than in the model group (both P < 0.05), and significantly higher in the model group than in the blank group (both P < 0.05). Conclusion Fraxetin may play a therapeutic role in a monosodium iodoacetate-induced rat model of osteoarthritis through the p38 MAPK pathway.

    Establishment of a Rat Model of Alzheimer's Disease by Introducing Human Triple Mutant APP Gene into Hippocampus via Brain Stereotactic Technology
    XIAO Linlin, YANG Yixuan, LI Shanshan, LUO Lanshiyu, YIN Siwei, SUN Juming, SHI Wei, OUYANG Yiqiang, LI Xiyi
    2025, 45(3):  269-278.  DOI: 10.12300/j.issn.1674-5817.2025.030
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    Objective To establish a rat model of Alzheimer's disease (AD) expressing human triple mutant amyloid precursor protein (APP) in the hippocampus, and to provide a model for the study of disease mechanisms and drug development. Methods Twenty-four 12-week-old SPF-grade female SD rats were randomly divided into a blank control group, a virus control group and an experimental group, with eight rats in each group; among them, the experimental group received a stereotaxic injection of adeno-associated virus (AAV) carrying the human triple mutant APP and NanoLuc luciferase genes into the hippocampus. In vivo imaging was used to observe viral expression in the brains of rats in each group, the novel object recognition test was used to assess the recognition memory of the rats in each group, real-time fluorescent quantitative PCR was used to detect the expression level of the APP gene, HE staining was used to examine the brain histopathology, Nissl staining was used to assess the hippocampal lesions, and immunohistochemistry was used to detect the deposition of amyloid β-protein (Aβ). Results In vivo imaging showed that reporter fluorescence was detected in the brains of rats in both experimental and virus control groups. Fluorescence quantitative PCR showed that the expression level of the APP gene was significantly increased in the brains of rats in the experimental group (P<0.01). Novel object recognition test revealed that the recognition memory of rats in the experimental group was significantly reduced compared with that of the blank control group (P<0.01). Six months after recombinant AAV virus infection, HE staining and Nissl staining of brain tissues showed that the number of neurons and Nissl bodies in the CA1 region of the hippocampus in the experimental group was reduced and disorganized; immuno-histochemistry testing of the CA1 region of the hippocampus and the pyramidal cell layer of the experimental group revealed prominent brown deposits, indicating Aβ protein deposition. Conclusion The rat model successfully established by stereotaxic injection and AAV-mediated delivery of human triple mutant APP gene exhibits typical AD features, providing a valuable animal model for studying AD pathology and developing drug therapies targeting Aβ protein deposition.

    Optimization of Surgical Procedure and Efficacy Evaluation of Aortic Calcification Model in Rats with Chronic Kidney Disease
    PAN Yicong, JIANG Wenhong, HU Ming, QIN Xiao
    2025, 45(3):  279-289.  DOI: 10.12300/j.issn.1674-5817.2024.128
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    Objective To establish a chronic kidney disease-associated aortic calcification model in SD rats using different nephrectomy surgical methods, and to compare and evaluate surgical duration and survival time to explore a more optimized modeling method. Methods According to different surgical methods, the SD rats were divided into four groups: Group A: intraperitoneal resection of 2/3 of the left kidney followed by right total nephrectomy in the second stage; Group B: intraperitoneal resection of 2/3 of the left kidney and simultaneous right total nephrectomy; Group C: dorsal approach right total nephrectomy followed by resection of 2/3 of the left kidney in the second stage; Group D: dorsal approach resection of 2/3 of the left kidney followed by right total nephrectomy in the second stage. After comparing survival curves of SD rats undergoing intraperitoneal versus dorsal approaches, and staged versus single-stage nephrectomy, the optimal nephrectomy surgical method was determined. Then, twenty-four 8-week-old SPF-grade male SD rats were selected for nephrectomy combined with calcitriol-induced calcification. Experimental group (12 rats): the dorsal approach left 2/3 nephrectomy followed by right total nephrectomy, with intraperitoneal injection of 1 μg/kg calcitriol administered one week later to induce aortic calcification. Control group (12 rats): the intraperitoneal injection of 250 μL/kg physiological saline containing 1% DMSO one week after sham surgery. After intraperitoneal injection of drugs for 3 months, the survival status of rats in each group was observed. Under anesthesia, blood samples were collected from each group to measure serum phosphorus and calcium ion concentrations, as well as serum urea nitrogen and creatinine levels. After euthanizing the rats, a post-mortem examination was performed to observe the residual kidney morphology, and HE staining was used to observe the pathological changes in the coronal section of the kidney. Additionally, the entire aorta of each group was taken, and the degree of aortic calcification was observed by staining with Alizarin red S and von Kossa. Real-time fluorescence quantitative PCR was used to detect the gene expression of smooth muscle actin-associated protein alpha (Sm22), Runt-related transcription factor 2 (Runx2), and osteopontin (OPN) in rat aortic tissue to evaluate the effectiveness of the model. Results The exploratory optimization experiment of different surgical procedures found that the survival rate of group D rats,which underwent 2/3 left kidney resection followed by right whole kidney resection via the dorsal approach, was the highest, indicating that this surgical procedure was the best method for establishing a chronic kidney disease model with renal dysfunction. The experimental group rats treated with this surgical procedure combined with high-dose calcitriol injection had significantly lower serum calcium ion concentration than those in the sham-operated control group (P<0.05), while serum phosphorus ion concentration, serum creatinine, and serum urea nitrogen levels were significantly higher than those of the control group (P<0.05). HE staining of the kidneys showed significant organic changes in the kidneys of the experimental group rats, with a significant decrease in glomerular count compared to that of the control group (P<0.05), indicating the successful establishment of a renal failure model. Alizarin red S staining showed significant pigment deposition in the aortic media of the experimental group rats, while von Kossa staining showed significant silver nitrate deposition in the aortic media of the experimental group rats, which was consistent with the manifestation of aortic calcification in renal failure. Real-time fluorescence quantitative PCR showed that the expression level of Sm22 in the aortic tissue of the experimental group rats decreased (P<0.05), while the expression levels of OPN and Runx2 increased (P<0.05), indicating a transition of aortic smooth muscle cells from smooth muscle phenotype to bone-like phenotype and successful induction of an aortic calcification model. Conclusion The method of establishing an aortic calcification model of chronic kidney disease in SD rats by first removing two-thirds of the left kidney via the dorsal approach followed by right total nephrectomy, combined with high-dose calcitriol administration, shortens the surgical time, improves the success rate of modeling, and increases the animal survival rate.

    Advances in Mouse Models of Amyotrophic Lateral Sclerosis
    LUO Lianlian, YUAN Yanchun, WANG Junling, SHI Guangsen
    2025, 45(3):  290-299.  DOI: 10.12300/j.issn.1674-5817.2024.161
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    Amyotrophic lateral sclerosis (ALS) is an irreversible, fatal neurodegenerative disorder whose incidence is positively correlated with the aging population. ALS is characterized by the progressive loss of motor neurons, leading to muscle weakness, atrophy, and ultimately respiratory failure. The pathogenesis of ALS involves multiple factors, including genetic and environmental influences, with genetic factors playing a particularly significant role. To date, several causative genes have been identified in ALS, such as the Cu/Zn superoxide dismutase 1 (Cu/Zn SOD1, also known as SOD1) gene, transactive response DNA-binding protein 43 (TDP-43) gene, fused in sarcoma (FUS) gene, and chromosome open reading frame 72 (C9orf72). Mutations in these genes have been found not only in familial ALS but also in sporadic ALS. Based on the identified ALS risk genes, various ALS animal models have been established through multiple approaches, including transgenic models, gene knockout/knock-in models, and adeno-associated virus-mediated overexpression models. These models simulate some typical pathological features of human ALS, such as motor neuron loss, ubiquitinated inclusions, and neuromuscular junction degeneration. However, these models still have limitations: (1) single-gene mutation models are insufficient to fully replicate the complex multi-factorial pathogenesis of sporadic ALS; (2) significant differences in microenvironmental regulation mechanisms and the rate of neurodegeneration between model organisms and humans may affect the accurate reproduction of disease phenotypes and the reliable evaluation of drug efficacy. To better understand the pathogenesis of ALS and promote the development of effective therapies, constructing and optimizing ALS animal models is crucial. This review aims to summarize commonly used ALS gene mutation mouse models, analyze their phenotypes and pathological characteristics, including transgenic mouse models, gene knockout/knock-in mouse models, and adeno-associated virus-mediated overexpression mouse models, and further discuss their specific applications in ALS pathogenesis research and drug development by comparing the advantages and limitations of each model.

    Construction and Preliminary Application of Animal Disease Model Digital Atlas Database Platform
    LI Huiping, GAO Hongbin, WEN Jinyin, YANG Jinchun
    2025, 45(3):  300-308.  DOI: 10.12300/j.issn.1674-5817.2024.158
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    Objective Domestic research institutions and researchers have established a wide variety of animal disease models and accumulated a wealth of specialized, distinctive, and targeted atlas data during the model development process. These atlas data are of great value for development and application. Therefore, it is necessary to develop a professional and complete digital atlas database platform for animal models, which can achieve the open sharing of animal model atlas data and the integration and optimization of atlas resources related to disease animal models held by relevant domestic institutions. Methods Based on the B/S architecture, the authors' institution built a digital atlas database of animal models, using Java as the main development language and Oracle database system along with related auxiliary tools. The database platform ran in a Linux environment and could be accessed by users through a web browser. At present, the data on this platform mainly came from the atlas resources submitted by animal model resource units within Guangdong Province. Results In August 2024, a digital atlas database platform for animal models was constructed based on the classification structure of three dimensions: systemic diseases, animal species, and resource units. This platform provided functions such as collection, management, retrieval, and viewing of atlas data. As of January 2025, four resource units had submitted 61 atlas data entries of animal models to the platform, totalling 610 data items. Conclusion The animal model digital atlas database platform has been constructed and put into preliminary use. Although the amount of data on the platform is still limited, it is capable of integrating and openly sharing animal model atlas data. It is believed that with the continuous enrichment of atlas data in the future, this platform is expected to provide important data support for the development of laboratory animal science and comparative medicine research, thereby promoting the efficient utilization of scientific research resources.

    Animal Experimental Techniques and Methods
    Reshaping Intercellular Interactions: Empowering the Exploration of Disease Mechanisms and Therapies Using Organoid Co-Culture Models
    TAN Dengxu, MA Yifan, LIU Ke, ZHANG Yanying, SHI Changhong
    2025, 45(3):  309-317.  DOI: 10.12300/j.issn.1674-5817.2024.164
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    The organoid co-culture model, as a novel tool for recreating a three-dimensional microenvironment to study cell-cell interactions, has demonstrated significant application potential in biomedical research in recent years. By simulating the in vivo tissue microenvironment, this model provides a more precise experimental platform for investigating complex cellular interactions, particularly in areas such as tumor immune evasion mechanisms, drug sensitivity testing, and the pathological characterization of neurodegenerative diseases, where it has demonstrated significant value. However, the organoid co-culture model still faces several challenges in terms of standardized procedures, large-scale cultivation, ethical guidelines, and future development. In particular, in the field of laboratory animal science, how to effectively combine organoids with traditional animal models, and how to select the most appropriate model for different research needs while exploring its potential for replacement, remain pressing issues. In the context of ethical approval and the replacement of animal experiments, the organoid co-culture model offers an experimental approach that better aligns with the "3R" principle (Replacement, Reduction, Refinement), potentially becoming an important tool for replacing traditional animal models. To this end, this paper reviews the latest advances and key challenges in this field, providing a detailed description of the construction methods for organoid co-culture models and discussing their applications in disease mechanism research and drug screening. The paper also systematically compares the organoid co-culture models with traditional animal models, exploring the criteria for selecting the appropriate model for specific applications. Furthermore, this paper discusses the potential value of organoid co-culture models as alternatives to animal experiments and anticipates future development trends of this technology. Through these discussions, the paper aims to promote the innovation and development of organoid co-culture technology and provide new perspectives and scientific evidence for future research.

    Prospects for 3D Bioprinting Research and Transdisciplinary Application to Preclinical Animal Models
    HU Min, DONG Lexuan, GAO Yi, XI Ziqi, SHEN Zihao, TANG Ruiyang, LUAN Xin, TANG Min, ZHANG Weidong
    2025, 45(3):  318-330. 
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    Animal experiments are widely used in biomedical research for safety assessment, toxicological analysis, efficacy evaluation, and mechanism exploration. In recent years, the ethical review system has become more stringent, and awareness of animal welfare has continuously increased. To promote more efficient and cost-effective drug research and development, the United States passed the Food and Drug Administration (FDA) Modernization Act 2.0 in September 2022, which removed the federal mandate requiring animal testing in preclinical drug research. In April 2025, the FDA further proposed to adopt a series of "new alternative methods" in the research and development of drugs such as monoclonal antibodies, which included artificial intelligence computing models, organoid toxicity tests, and 3D micro-physiological systems, thereby gradually phasing out traditional animal experiment models. Among these cutting-edge technologies, 3D bioprinting models are a significant alternative and complement to animal models, owing to their high biomimetic properties, reproducibility, and scalability. This review provides a comprehensive overview of advancements and applications of 3D bioprinting technology in the fields of biomedical and pharmaceutical research. It starts by detailing the essential elements of 3D bioprinting, including the selection and functional design of biomaterials, along with an explanation of the principles and characteristics of various printing strategies, highlighting the advantages in constructing complex multicellular spatial structures, regulating microenvironments, and guiding cell fate. It then discusses the typical applications of 3D bioprinting in drug research and development,including high-throughput screening of drug efficacy by constructing disease models such as tumors, infectious diseases, and rare diseases, as well as conducting drug toxicology research by building organ-specific models such as those of liver and heart. Additionally,the review examines the role of 3D bioprinting in tissue engineering, discussing its contributions to the construction of functional tissues such as bone, cartilage, skin, and blood vessels, as well as the latest progress in regeneration and replacement. Furthermore, this review analyzes the complementary advantages of 3D bioprinting models and animal models in the research of disease progression, drug mechanisms, precision medicine, drug development, and tissue regeneration, and discusses the potential and challenges of their integration in improving model accuracy and physiological relevance. In conclusion, as a cutting-edge in vitro modeling and manufacturing technology, 3D bioprinting is gradually establishing a comprehensive application system covering disease modeling, drug screening, toxicity prediction, and tissue regeneration.

    Analysis of Common Causes of Out-of-Specification Results in the Test for Depressor Substances
    TONG Xiyang, QUE Changtian, ZHANG Feng, ZHAO Lu, WANG Hongping
    2025, 45(3):  331-339.  DOI: 10.12300/j.issn.1674-5817.2024.143
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    According to General Chapter 1145 of Division IV in the Chinese Pharmacopoeia (2020 Edition), the test for depressor substances is a common method for drug testing. It determines whether the level of depressor substances in a test sample complies with the specified standards by comparing the extent of blood pressure reduction in anesthetized cats induced by the histamine reference substance and the test sample. If an out-of-specification (OOS) result occurs in the test for depressor substances, it may be caused by inherent quality issues of the drug or errors in the testing process. Therefore, analyzing the causes of OOS is particularly important for confirming the test results and evaluating drug quality. Cats are used as experimental animals in the test for depressor substances. Compared with conventional laboratory animals, they are less stable, surgery procedures are more challenging, and the testing process is more complex. These factors make it more difficult to investigate the causes of OOS in this test. Based on a review of the literature and practical work experience, this article analyzes the causes of OOS in the test for depressor substances from the following five aspects: (1) an analysis of the impact of drug standards on OOS from three aspects: standard determination, standard content, and standard drafting; (2) personnel qualifications, including pre-employment training, compliance with standard operating procedures during experimental operations, and the ability to operate instruments; (3) factors related to cats, used as experimental animals in the test for depressor substances, including physiological characteristics, genetic background, and abnormal conditions during the experiment; (4) reference substances, reagents, test samples, and key instruments such as the multi-channel physiological signal instrument; (5) experimental operations including animal anesthesia, arterial and venous catheterization, drug administration, and data processing. This article aims to provide reference approaches for professionals engaged in the testing of pharmaceuticals and biological products when analyzing the causes of OOS in the test for depressor substances.

    Development and Utilization of Laboratory Animal Resources
    Identification and Analysis of MHCⅡ Genes in Wuzhishan Pigs
    LIU Yuanyuan, XIN Wenshui, CHAO Zhe, CAO Zongxi, CAI Yifei, LI Qiang, LI Lingwei, LIU Guangliang
    2025, 45(3):  340-348.  DOI: 10.12300/j.issn.1674-5817.2024.135
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    Objective To obtain the gene sequences of major histocompatibility complex (MHC ) Ⅱgenes of Wuzhishan pigs, analyze their genetic information, and explore the biological functions of their MHC system. Methods Spleen samples were collected from 3 adult male Wuzhishan pigs. Primers were designed according to MHCⅡ gene sequences, and the coding sequences of Wuzhishan pig MHCⅡ genes were amplified by RT-PCR. Sanger sequencing was performed to determine the full-length sequences. Bioinformatics tools were employed to analyze the physicochemical properties, phylogenetic relationships, conserved motifs, structural domains, chromosomal localization, and syntenic relationships of these genes. Results Eight MHCⅡ genes were identified in Wuzhishan pigs, designated as SLA-DRA, SLA-DQA, SLA-DQB, SLA-DRB, SLA-DOB, SLA-DMB, SLA-DMA and SLA-DOA. The full-length sequences of these genes were determined by Sanger sequencing and subsequently deposited in GenBank under accession numbers PQ182796, PQ182797, PQ182798, PQ182799, PQ182800, PQ182801, PQ182802, and PQ164779. Phylogenetic analysis showed that the six MHCⅡ genes of Wuzhishan pigs clustered separately from their counterparts in Duroc, Meishan, Large White, and Bama pigs, indicating distinct evolutionary trajectories. Bioinformatics analysis demonstrated that most MHC Ⅱ proteins were hydrophobic, with molecular weights ranging from 27 700 to 30 000 Da. Genes within the same subregion shared conserved motifs. Specifically, four MHCⅡ proteins encoded by SLA-DQB, SLA-DRB, SLA-DOB, and SLA-DMB contained the MHCⅡβ conserved domain, while those encoded by the genes SLA-DRA, SLA-DQA, SLA-DMA, and SLA-DOA contained the MHCⅡα conserved domain. The eight MHCⅡ genes were scattered along the long arm of chromosome 7 in the Wuzhishan pigs, exhibiting syntenic relationships with three human genes and five Duroc pig genes. Conclusion The MHCⅡ genes of Wuzhishan pigs may possess a unique evolutionary origin.

    Research Progress on Characteristics Analysis of Gut Microbiota and Its Sex Differences in Laboratory Animals
    SHEN Huangyi, HUANG Yufei, YANG Yunpeng
    2025, 45(3):  349-359.  DOI: 10.12300/j.issn.1674-5817.2024.124
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    Laboratory animals serve as the cornerstone in life science research, acting as surrogate models for human physiology, pathology, and disease treatment. They play an irreplaceable role in basic research, drug development, and translational medicine. Gut microbiota, a complex microbial community comprising bacteria, fungi, viruses, and unicellular organisms, colonizes the host's intestinal tract and is closely associated with the maintenance of normal physiological metabolism and overall health. Studies have shown that dysbiosis of the gut microbiota can lead to various diseases, including obesity, diabetes, hypertension, inflammatory bowel disease, and Alzheimer's disease. Therefore, conducting characteristic analyses of the gut microbial composition of laboratory animals can not only enhance the reliability of experimental outcomes but also facilitate their translational application. Sex differences represent a critical variable in biological research, significantly influencing the physiological functions, metabolic traits, and gut microbial composition of laboratory animals. However, a pronounced sex bias has been widely observed in many biological studies, thereby limiting the generalizability of results. This study focused on ten commonly used laboratory animals in life sciences, including mice, rats, guinea pigs, hamsters, rabbits, dogs, cats, non-human primates, miniature pigs, and chickens. Their gut microbial composition was summarized and related sex-specific differences of certain species were analyzed. Furthermore, by comparing the gut microbiota of laboratory animals with that of humans, this study offers novel perspectives for comparative medical research. In summary, this study not only deepens researchers' understanding of gut microbiota characteristics and sex-dependent variations across laboratory animal species but also provides practical guidance for selecting appropriate laboratory animals, constructing sex-specific disease models, and interpreting experimental results in scientific studies.

    Quality Control of Laboratory Animals
    Diagnosis of an Outbreak of Canine Distemper in Cynomolgus Monkeys in an Experimental Monkey Farm in 2019
    WANG Chenjuan, YANG Lingyan, WANG Lipeng, SUN Xueping, LI Jingwen, GUO Lianxiang, RONG Rong, SHI Changjun
    2025, 45(3):  360-367.  DOI: 10.12300/j.issn.1674-5817.2024.160
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    Objective To report the diagnosis of a canine distemper virus outbreak among a colony of cynomolgus monkeys at an experimental monkey farm in 2019. Methods A total of 46 samples were collected from 21 diseased cynomolgus monkeys (exhibiting symptoms such as facial rash, skin scurf, runny nose, and diarrhea) and from one deceased monkey at an experimental monkey breeding farm in South China in late 2019, including serum, skin rash swabs, and anticoagulated whole blood, liver, lung, and skin tissues were submitted for testing. All submitted samples were tested for canine distemper virus gene fragments using real-time quantitative PCR, while immunohistochemical staining was performed to detect canine distemper virus nucleoprotein in lung tissues. The skin tissue of the deceased monkey was ground and sieved. The filtrate was inoculated into a monolayer MDCK cell line for virus isolation. Then, whole-genome sequencing was performed to identify the isolated virus. The Clustal Omega tool was used to align and analyze the homology of different Asian canine distemper virus isolates. A phylogenetic tree was constructed, followed by genetic evolutionary analysis. Results Clinical retrospective analysis revealed that the diseased cynomolgus monkeys exhibited symptoms similar to those observed in cynomolgus monkeys infected with measles virus. Necropsy findings showed red lesions in the lungs and significant hemorrhage in the colonic mucosa. Real-time quantitative PCR detected canine distemper virus nucleic acid in the serum, skin rash swabs of the infected monkeys, and various tissue samples of the deceased monkey, all of which tested positive. Calculation based on the standard curve formula indicated the viral load was highest in the skin tissue. Immunohistochemical staining of the deceased monkey's lung tissue demonstrated aggregation of CDV nucleoprotein in alveolar epithelial cells, bronchi, and bronchioles. A CDV strain was isolated from the skin tissue of the deceased monkey. Phylogenetic analysis indicated that this strain shares the closest relationship (98.86%) with the Asian-1 type canine distemper virus strain CDV/dog/HCM/33/140816, previously identified in dogs in Vietnam. Conclusion Based on comprehensive analysis of clinical symptoms, nucleic acid detection, viral protein immunohistochemistry, and whole-genome sequencing results, the diagnosis confirms that the cynomolgus monkeys in this facility are infected with canine distemper virus. It is recommended to include canine distemper virus as a routine surveillance target in captive monkey populations. Additionally, this study provides a foundation for further research on the molecular biological characteristics of canine distemper virus.

    Isolation and Identification of Staphylococcus xylosus in Nude Mice with Squamous Skin Scurfs
    KONG Zhihao, WEI Xiaofeng, YU Lingzhi, FENG Liping, ZHU Qi, SHI Guojun, WANG Chen
    2025, 45(3):  368-375.  DOI: 10.12300/j.issn.1674-5817.2024.166
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    Objective To isolate pathogenic bacteria from the skin of a nude mouse exhibiting squamous skin scurfs, and perform bacterial identification, traceability analysis, and pathogenicity studies to provide a new approach for the diagnosis of pathogens in nude mice with squamous skin scurfs. Methods Skin swab samples were collected from a nude mouse exhibiting squamous skin scurfs for nucleic acid testing, bacterial isolation and culture, biochemical identification, 16S rDNA gene amplification and sequencing, and whole genome sequencing to construct a phylogenetic tree. Fifteen BALB/c nude mice were randomized into a saline-treated control group, a high-concentration group treated with 1.8×10? CFU/mL of the isolated bacterial suspension, and a low-concentration group treated with 1.8×10? CFU/mL of the isolated bacterial suspension. Pathogenicity was assessed by animal infection experiments and observation of histopathological changes in skin tissue using HE staining. Results The nucleic acid test for Corynebacterium bovis was negative, excluding infection by this organism. The pathogen isolated on mannitol salt agar and blood agar, combined with Gram staining, suggested a Gram-positive Staphylococcus species. The isolated strain was identified by 16S rDNA sequencing and a fully automated microbial identification system as Staphylococcus xylosus. Phylogenetic tree analysis based on whole genome sequencing showed that the strain was most closely related to an isolate from leafy vegetables in South Korea (GenBank GCA_00207825.1). In the high-concentration group, squamous skin scurfs appeared on the head, neck, and back of nude mice on the 17th day post-infection, while in the low concentration group, similar symptoms appeared on the 20th day post-infection and gradually spread to other areas. The scaling symptoms were transient, lasting for 7 days in the high-concentration group and 3 days in the low-concentration group, after which the skin returned to normal. The infection rate was 33.33% in both the high- and low-concentration groups. No significant pathological changes were observed in the skin tissues of infected mice compared to the control group, indicating marked individual differences in the pathogenicity of the strain in nude mice. Conclusion A strain of Staphylococcus xylosus was isolated from the skin of a nude mouse exhibiting squamous skin scurfs. The strain is an opportunistic pathogen that causes transient squamous skin scurfs without significant histopathological changes, and there are individual differences in the sensitivity of nude mice to this strain. These findings can provide valuable data for pathogen identification in immunodeficient or gene knockout mice.