Abstract:生物学家对特定的动物物种进行科学研究，用于揭示某种具有普遍规律的生命现象或药物的作用机制，这些特定的动物物种即被称为模式动物。在生命科学的发展历程中，模式动物发挥了重要的作用。例如：果蝇模型的建立加速推进了遗传学和发育生物学的发展；利用大鼠、小鼠构建的基因敲除和敲入动物模型，为包括生物化学与生物物理学在内的蛋白质科学相关研究提供了重要工具；构建人类疾病的非人灵长类动物模型为神经科学和心理学等领域发展做出了重要贡献。中国各类型的动物资源以其科研条件中的基础性地位与领域广益性，成为支撑生命科学各领域发展与创新的重要战略资源之一，也是实现科技进步、促进经济社会可持续发展、提高中国科技国际地位的基础支撑条件［1-2］。
在各类型模式生物中，最常用的应当是实验动物。实验动物是指经人工饲育，对其携带的病原体实行控制，遗传背景明确或来源清楚，用于生命科学和医药领域研究的动物。随着近年来在生物技术领域的大幅进步，中国动物模型资源在新品系研究与开发、新品种保藏与应用、生物化学与生物物理研究等基础研究领域取得了长足进展。同时，中国在利用CRSIPR/Cas9 基因编辑技术开展各类型基因修饰动物模型研发方面已达到国际领先水平，近年来产生了一批在世界范围内有显著影响力的科研成果［3］。
本期《动物模型研究专刊》汇总了近年来在生命科学研究中常用的，包括线虫、果蝇、大鼠、小鼠、长爪沙鼠、鸣禽、斑马鱼、小型猪、树鼩和实验猴等在内的模式生物，讨论了动物模型在包括听觉、衰老、语言学习、航天、动物医学等多方面的研发与应用进展，特别是人类疾病模型方面，展示了动物模型在糖尿病、神经退行性疾病、器官移植、心理研究、中医药研究等领域中的应用。另外，鉴于新型冠状病毒肺炎（COVID-19） 特别是奥密克戎毒株引发的疫情近期仍在国内广泛传播，本期专刊还包括了用于新冠肺炎疫苗研发的动物模型和树鼩病毒感染模型的研究进展，以飨读者。
希望通过《动物模型研究专刊》的发行，让更多从事生物化学与生物物理相关研究的读者了解各类型模式动物与动物模型在生命科学和医学等领域的重要应用，认识新的动物模型的开发、生产、使用及发展需求，为在中国建立资源更为丰富、品种品系结构合理的模式生物研发与共享平台，为建成满足国家科技创新需求的实验动物资源研发与共享服务体系，为推动中国生命科学和医学相关研究发挥积极作用。

Abstract:Viral infection is a global public health threat causing nearly half of the incidence rate of major infectious diseases in China. Establishment of an animal model to mimic the progression of viral infectious diseases in humans is of great significance to study the pathogenesis and prevention of viral infectious diseases.Tree shrews, as the close relatives of primates, have a higher similarity with humans in physiology, biochemistry, genomics than rodents. Tree shrew has unique characteristics that render it a potentially advantageous animal model, including small body size, short reproductive cycle and life span, easy handling, low maintenance cost, and it can infect a variety of viruses related to human diseases. In this paper, the biological advantages of tree shrew as a novel animal model of viral infectious diseases are summarized, including distribution and evolutionary status, biology and physiology. In addition, the latest application of tree shrew in the research of many viral infectious diseases such as in hepatitis B virus, hepatitis A virus and other virus were compared and summarized.

Abstract:Conditional gene-editing system can limit gene modification occur in specific tissues or organs at a specific time, which can be realized by introducing conditional gene deletion system and conditional gene overexpression system into animals, and has been widely used in the study of gene function in mice. Gene-editing pigs have important application value in agriculture and biology. In the field of biological medicine, because of the similarities of body, organ size, physiology, metabolism, and life with humans, genetically-modified pigs can be used for the basic research of gene function, and as a model of human disease, xenotransplantation supply and human functional protein bioreactor. Benefit from the development of gene editing technology in recent years, it is possible to introduce the conditional gene expression system in pigs, and conditional gene expression pig model will greatly promote the research progress. In this paper, we review the progress in the construction of conditional modification systems and genetically-modified pig models by using gene editing techniques.

Abstract:The biological characteristics of primates, such as genetics, behavior, cognition, physiological, biochemical, are closer to those of humans. The study results from primates are easily applied on human due to having superior brain function structure and neural activity that other experimental animals can’t replace. Primates are considered the most ideal animal model for human neurological diseases. Primates are often used to establish neurodegenerative diseases, psychiatric diseases and other diseases animal models, in order to study the pathogenic mechanism, treatment and drug development of above diseases. As a model organism, primates have made irreplaceable contributions to human neuroscience and related medical research. Here we review the recent progress, status, and future prospects and challenges facing the development and deployment of the application of primates in above diseases animal model research.

Abstract:Visceral pain is pathological pain and common clinical symptoms sourced from internal organs exposed to noxious stimuli such as mechanical stretch, inflammation, spasm, and ischemia. Compared with somatic pain, the mechanisms of induction and maintenance of viseral pain and its modulation are more complex. It has been demonstrated that peripheral mechanisms, i.e. peripheral inflammation, variations of the number and function of ion channels/receptors, central sensitization, and imbalanced descending controls: inhibition and facilitation are all involved in visceral pain. Therefore, clarifying mechanisms of visceral pain is important in basic pain research as well as in the clinic. For the in-depth study of the complex mechanisms underlying visceral pain, the choice and establishment of experimental animal models that mimic the pathophysiological characteristics of clinical visceral diseases is an essential prerequisite for the exploration of visceral pain. One difficulty in establishing animal model of visceral pain is that the experimental animal model cannot completely simulate the pathophysiological characteristics of clinical visceral diseases, and visceral diseases may be accompanied by a series of complications. In addition, repeatability, easiness and economy should be considered during the establishment of the animal model of visceral pain. At present, there are various animal models and classification methods of visceral pain, during which no authoritative classification of visceral pain animal models is validated. Currently, animal model of visceral pain is classified according to the method of visceral stimulation, such as inflammatory factors, mechanical dilative, ischemic, and electrical stimulation. Besides, visceral pain model can be classified according to the location of occurrence, i.e. heart, gastroduodenum, pancreas, small intestine, colorectal, ureter, bladder and uterus. The establishment of an ideal experimental animal model in line with the pathophysiological characteristics of clinical visceral diseases is of great significant and critical to explore the mechanisms of induction, maintenance, and regulation in visceral pain, and to further screen the therapeutic drugs for related visceral diseases. The aim of current review is to summary the preparation and characteristics of common experimental animal visceral pain models, and provide relative documents for basic researchers and clinicians to select appropriate animal models in exploring visceral pain, better understanding the associated mechanisms, and providing available therapeutic strategy.

Abstract:By the end of 2021, the Omicron mutant of SARS-CoV-2 rapidly replaced the Delta mutant and became widely prevalent worldwide. Its S protein was mutated at 36 sites, resulting in significant changes in virulence and transmissibility, and was capable of immune escape. Both human and animal studies showed that the Omicron mutant was less virulent than the previous circulating strains. Vaccination is currently the most common means of epidemic prevention and control. Studies have found that the protection of vaccines against Omicron mutant strains has significantly decreased. Therefore, animal models are needed to evaluate the effectiveness of new immunization strategies or specific/polyvalent vaccines against Omicron. Animal experiments showed that booster immunization can prevent Omicron infection to a certain extent, which is one of the important directions to explore the immunization strategy against Omicron mutant. Besides, protective effects of specific and polyvalent vaccines have also been preliminarily confirmed, and subsequent preclinical trials are progressing. The development of polyvalent vaccines against existing and potential mutant strains is of great significance for epidemic prevention and control. In laboratory conditions, using animal model to carry out live virus attack experiment is a key technical means to verify the effectiveness of protective neutralizing antibody and vaccine in vivo. This article will review the research progress of vaccine against Omicron variant strain from the direction of animal model.

Abstract:Songbirds’ singing is similar to human language, which is a complex vocal learning behavior and is regulated by a group of interconnected nerve nuclei in the brain. These song control nuclei have a certain degree of structural homology with the brain regions related to human vocal control, and may share some basic regulation mechanisms of vocal learning. Therefore, songbirds have become an important model animal to study the neural mechanism of vocal learning, which can not only shed light on avian language learning, but also provide an important reference for understanding the neural process of human language learning and the treatment of language disorders. Willams Thorpe from University of Cambridge took the lead in bird singing research in 1948. Subsequently, many researchers in the United States used a variety of experimental techniques to carry out the study of birdsong neurobiology. In the 1960s, Chinese scholar Professor LAN Shu-Cheng first carried out the research on bird singing neurobiology in the Northeast Normal University, and then the researchers in Beijing Normal University, South China Normal University, Hainan Normal University and Jiangxi Science and Technology Normal University carried out the researches on the neural mechanism of bird singing using molecular biology and electrophysiological technology. In recent years, the application of songbird model in interdisciplinary research of vocal behavior and neurobiology mainly focuses on the mechanism of vocal plasticity; the neurotransmitters, sex hormones and other bioactive substances regulated the song behavior; the effect of auditory feedback on song behavior and application of photogenetic technology and genomics in this field. In the future, frontier technologies such as single cell sequencing and CRISPR/Cas9 gene editing have pushed these research fields to a deeper level. In addition, the effects of neurotransmitters on the neural network regulation of songbirds’ song control nuclei and song behavior need to be further studied. At the same time, the application of some new fluorescent probes will help to further reveal the regulatory role of neurotransmitters in the singing process of songbirds. The neurobiological study of songbirds’ song behavior will bring important enlightenment and theoretical support to the exploration of the pathogenesis and treatment of human language disorder related diseases. In conclusion, this paper systematically summarizes the research history, important findings and research progress of songbird song behavior, as well as the important enlightenment for the treatment of related central nervous system diseases.

Abstract:Bats have been used as model animals to study their hearing, echolocation, ecological adaptation and evolution, and lots of remarkable results have been achieved. In order to adapt to echolocation, the structure and function of the auditory system in bats have developed distinct specializations. In the constant frequency-frequency modulation (CF-FM) bat cochlea, the so-called auditory fovea is formed, and the functional organization of auditory cortex is modular, which has become a representative specialized symbol. The latency of neuronal response is not only a fundamental characteristic of bats, but also a part of the regulation of echolocation behavior. It is found that neurons with longer latencies have sharper echo-delay tuning characteristics, while neurons with shorter latencies have wider echo-delay tuning characteristics. Frequency tuning of bat auditory neurons is far greater precision than humans and other non-echolocation animals. Moreover, the afferents originating from the cochlear auditory fovea show overrepresentation of CF components of the second harmonic of echolocation signals at all levels of auditory centers, so as to meet the needs of target echo Doppler drift detection. Duration is one of the actively changeable parameters of echolocating bat vocalization signals. The duration-tuned neurons provide an important neural mechanism for encoding the temporal features of sound, matching the need for processing the temporal information of echolocation signals. Echo-delay tuned neurons have been found in the auditory center of many echolocation bats, which not only can tune the target range, but also the azimuth and elevation of the echo, thus playing an important role in the three-dimensional representation of the target location. In the inferior colliculus of CF-FM bats, neurons showed single-on and double-on response patterns to the CF-FM sound signal, which may be shaped by different local neural circuits. Based on the response properties of the auditory cortex neurons of mustached bats to echolocation signals, the auditory cortex neurons of Pteronotus parnellii can be divided into functional modules for processing different echo information. For example, neurons in CF/CF area are responsible for processing Doppler-shift magnitude, i.e. target velocity. The neurons in FM/FM area are sensitive to echo delay or target distance. Studies on corticofugal control indicate that this control system provides a structural and functional guarantee for subcortical acoustic signal processing and plasticity changes in adaptation to the environment for adult bats. It has also been found that object-selective neurons exist in the auditory cortex of bats, which respond to auditory objects in a scale-invariant or size-constancy manner. This finding also provides evidence for the hypothesis that mammals follow a common mechanism for scale invariance of hearing. The dynamic representation of 3D space during flight not only exists in the cerebral cortex, but also in the auditory midbrain. It is now thought that different types of navigation neurons in the bats’ brains perform their respective functions to guide them to their destinations in 3D space and flight.

Abstract:Protein homeostasis is the core response of cells against stress. As an important organelle, mitochondria depend on a complex network of protein to perform normal functions, therefore protein homeostasis is significant to mitochondria. When the organism is exposed to external pressure, it produces alterations in protein homeostasis. In order to maintain the normal function, cells activate a transcriptional response mechanism called mitochondrial unfolded protein response (UPR^mt), which maintains mitochondrial protein homeostasis and restores mitochondrial function to cope with stress and maintain organism health. In this review, we present an overview of the relationship between mitochondrial protein homeostasis and UPR^mt, and focus on summarizing the relevant mechanisms associated with cell-autonomous and non-autonomous UPR^mt in C. elegans. Among them, the cell- autonomous UPR^mt contains the basic signaling pathways involved in transcription factors ATFS-1, DVE-1, UBL-5 and epigenetic mechanisms related to acetylation and methylation in histone modifications. In addition, although the downstream molecular mechanism is not clear, a novel signaling pathway, SPHK-1/S1P, independent of these common transcription factors, can also activate UPR^mt. Recently, in analogy to “cytokines”, a variety of factors produced by mitochondrial stress as “mitokines” has been found that participate in UPR^mt activation among different tissues. The neurotransmitter 5-HT, neuropeptide FLP-2, intercellular secretory factor WNT/egl-20, and FSHR-1 are involved in the neuronal-intestinal UPR^mt. Despite that the factor between germline and intestine is not found, mitochondrial CYC-2.1 reducing in germline still activates UPR^mt of intestinal cells. This is probably a self-protection and repair mechanism in evolution, which acts as “early warning” and activates the repair effect of distal tissues to respond rapidly and efficiently to the challenges posed by external damage. We also discuss the impact of UPR^mt on ageing. Affecting the imbalance between nDNA and mtDNA-encoded proteins in mitochondria can effectively induce UPR^mt and extend lifespan. In terms of stress responses, UPR^mt is beneficial to maintaining protein homeostasis by activating transcription and translation, causing metabolic reorganization, however, the activation of UPR^mt is not a sufficient condition for longevity. Perhaps the life-extending effect is just an additional benefit of UPR^mt on stress relief, or mild, short-term, qualified UPR^mt can extend lifespan, while strong, long-term, generalized UPR^mt activation may irrelevant. It provides new theoretical basis for further research.

Abstract:Objective The endogenous cystatin C (CysC), encoded by the CST3 gene, is highly expressed in the brain and has protective effects in a variety of neuropathological processes. The aim of this research is to investigate whether knocking out (KO) CysC in gerbils can induce an animal model of depression and the protective effect of CysC on endothelial cells and neuronal cells under simulated pathological conditions.Methods The transcription level of CysC in different tissues of CysC knockout (CysC-KO) gerbils was detected using qPCR. The behavior of CysC-KO gerbils was evaluated through sucrose preference test (SPT), social interaction (SI), novel object recognition test (NOR), light/dark boxes, and open field trials (OFT). And under the pathological conditions simulated by H&S (hypoxic and starvation) or OGD/R (oxygen glucose deprivation/reoxygenation) or inflammatory factor (TNF-α/LPS), MTT assay was used to detect the effect of CysC or its inhibitor on HUVEC (human umbilical vein endothelial cells) and N2a (mouse neuroblastoma N2a cells) viability.Results CysC expression in CysC-KO gerbils was significantly reduced in various tissues, especially in the brain. Deficiency of CysC in gerbils induces depression-like behavior, but does not affect motion and exploration behavior. CysC significantly improved proliferation of both endothelial cell and neuronal cells under H&S, OGD and inflammatory conditions, while CysC inhibitor harbored contrary effect.Conclusion The CysC-KO gerbils exhibited depression-like behavior, which may be caused by the loss of the protective effect of CysC in vascular endothelial cells and neuronal cells. These results provide a new gerbil model for studying the neuroprotective effects of CysC and the mechanism of depression.

Abstract:Objective Zebrafish is one of the most widely used model animals for scientific research in the world. The health and quality of zebrafish are the basis for accurate data and reliable results. With the rapid development of zebrafish related research in China, the number of fish diseases in research facilities has been increasing in recent years. However, the research and analysis on these diseases have been lacking. A novel lethal disease, “hole in the head” disease has spread in several zebrafish facilities since 2018, whose pathogen was unrecognized and hard to be controlled. Pathogen identification is urgently needed, and the analysis and advice of health administration are required for the fast-growing field.Methods We necropsied the brain tissue from the “hole in the head” disease zebrafish. After the brain tissue was homogenized, the pathogen was isolated and cultured on brain heart infusion agar (BHIA) plates. The isolated pathogen was analyzed for biochemical characteristics and 16S rDNA homology. The Koch’s Postulate was fulfilled to confirm the pathogen. In addition, we analyzed the zebrafish disease data collected by China Zebrafish Resource Center (CZRC) from 2017 to 2021 and summarized the characteristics of various common diseases.Results The isolated and identified pathogen of the “hole in the head” disease has the same physicochemical properties with Edwardsiella ictaluri, which also fulfilled the Koch’s Postulate. The 16s DNA sequence of this pathogen was highly homologous to Edwardsiella ictalurid. From 2017 to 2021 CZRC has collected 121 disease and fish death cases in Chinese zebrafish facilities. We found that 50.4% fish health problems were directly or indirectly caused by equipment failure and abiotic factors, including 12.39% fish death caused only by improper equipment maintenance and water quality problems. The most lethal problem was gas poisoning. Among all the known pathogens, bacterial pathogens were the most common, accounting for 83.46%, fungal pathogens accounted for 2.47%, and parasitic pathogens accounted for 1.65%. Among all the known bacterial diseases, the opportunistic pathogens of the genus Aeromonas were the most common, followed by Edwardsiella, accounting for 34.65% and 23.76% respectively.Conclusion Edwardsiella ictaluri was isolated and identified as the pathogen of “hole in the head” disease. The highest incidence of zebrafish disease is bacterial infection, and nearly half of zebrafish health problems are caused by abiotic factors. Well-maintained equipment and proper water quality are the most important prerequisites to ensure the health of zebrafish, managements of daily hygiene are the main means to prevent fish diseases, and the prevention of bacterial diseases is the top priority of zebrafish farming.

Abstract:Objective To estabolish a new mouse animal model that mimics the pathological characteristics of space weightlessness.Methods Male C57BL/6J mice were randomly divided into 4 groups. (1) Standard model group: mice with hindlimb unloading (HU); (2) control group: wild-type mice; (3) Sham operation group: mice with phosphate buffer solution (PBS)-injected into fastigial nucleus (FN); (4) new model group: mice with excessive formaldehyde (FA)-injected into FN. All these mice were used to assessthe ability of move and balance by using accelerating rotarod, beam walking and gait analysis, respectively. After behaviors tests, cerebellar slices were used to examine the death of cerebellar neurons, biochemical detection of FA-generating enzyme: semicarbazide-sensitive amine oxidase (SSAO), and cerebellar FA concentration.Results Compared with control group, there were a marked elevation in activity and expression of SSAO, an increase in the levels of endogenous FA, and a massive death of cerebellar neurons associated with move disorders in HU model mice. More importantly, the new model mice with injectetion of FA into FN exhibited the similar pathological characteristics as to HU model, including motor disorders and biochemical indexes.Conclusion HU-enhanced activity and expression of SSAO in the cerebellum leads to endogenous FA accumulation in the cerebellar FN. Exssesive FA is the direct factor for cerebellar neuron death and motor disorders. Moreover, FA-injection into FN mimics the pathological characteristics of HU model. This may provide a novel experimental animal model for drug screening via space weightlessness-induced motor disorders.

Abstract:Objective Learned helplessness (LH) refers to establishment of the helpless state in animals, which have experienced exposure to stressors that are inescapable by means of behavioral responses. It could affect their locomotor activity and other behaviors, such as circadian rhythm, food intake, immune system, etc. LH has been observed in many species including Drosophila melanogaster. Activity of LH flies decreased significantly after inescapable heat shocks. However, it is still unknown if there is impairment in learning ability in LH of Drosophila. Here, we explored if place learning ability of Drosophila could be effected by LH.Methods We established a new experimental paradigm and procedure for place learning and LH experiment in Drosophila.Results We observed robust place learning and LH phenomenon in the new paradigm. We also found that after long-term exposure to inescapable heat pulses their place learning ability was reduced.Conclusion Our findings reveal that LH in Drosophila not only effect their locomotor activity but also place learning behaviour.

Abstract: