Microtus fortis (reed vole) is the only mammal known to have natural resistance to Schistosomiasis japonica. Originating from schistosomiasis endemic and non-endemic areas, as well as laboratory bred voles have the same resistance to Schistosoma japonicum. After more than 30 years of laboratory cultivation of wild reed vole, a series of progress have been made in laboratory animalization. A detailed study was conducted on biological traits including growth and development, reproductive physiology, serum biochemistry, hematological indicators and tissue anatomy. At the same time, the anti-schistosomiasis characteristics and anti-schistosomiasis mechanisms of Microtus fortis were studied. The closed Dongtinghu population of Microtus fortis (S: DTMF) cultivated by Shanghai Laboratory Animal Research Center was recognized as a Chinese laboratory animal resource by the Experimental Animal Resources and Evaluation Working Committee of the Chinese Association for Laboratory Animal Sciences in 2021. This review focuses on summarizing the research progress in the biological characteristics, standardization research, genome and anti-schistosomiasis mechanism of reed vole in the past decade, especially in the implementation of the key project in the National Science and Technology Pillar Program.

Objective To measure and analyze biological characteristics and aging phenotype of SHJH ^hr mice and provide basic data for the application of the mouse model in aging mechanisms research and antiaging drug development. Methods With ICR mice of the same age as control group, the body mass growth data of SHJH ^hr mice at the age of 3 to 16 weeks, the reproduction ability of 1 to 4 fetuses and the life cycle of SHJH ^hr mice were measured. Blood routine (30 items) and serum biochemical indexes (25 items) of 6-week-old SHJH ^hr mice were measured. The venous blood of 8-week-old SHJH ^hr mice was collected for flow cytometry analysis to determine the content of immune cells. The aging bone structure of the cancellous bone and bone mineral density of SHJH ^hr mice aged 4, 8 and 26 weeks were measured by micro-CT. Histopathological changes of bone and joint of 8-week-old mice were observed. Results Compared with ICR mice, the female and male body mass of SHJH ^hr mice were significantly lower at the age of 16 weeks (P < 0.05), and the reproductive performance of female mice was low (P < 0.01) or did not have normal reproductive capacity. The shortest survival time of SHJH ^hr mice was 57 weeks and the longest was 71 weeks, which was shorter than those of normal ICR mice, showing obvious rapid aging phenomenon. At the same time, some physiological and biochemical indexes of blood and pathological changes of bone and cartilage tissues also showed the accelerated aging and abnormality of animal physiological functions. Conclusion SHJH ^hr mice have some biological characteristics of rapid aging as well as some physiological and pathological changes caused by aging.

Objective To analyze the microflora structure and abundance of ileum and colon of SPF male SD rats by high-throughput sequencing technique. Methods The ileal and colonic lumen contents of 30 SPF male SD rats were collected, the total bacterial DNA in the contents was extracted and amplified by PCR. The V3-V4 region of bacterial 16S rRNA in the samples was sequenced using Illumina NovaSeq sequencing platform. Then the species structure and abundance of the intestinal flora were analyzed at the phylum and genus level based on validated data. The diversity and differences between ileal and colonic flora were analyzed using the QIIME software (amplicon) analysis tool. The Tax4Fun program was applied to predict the dominant gene enrichment pathways of ileal and colonic flora. Results At the phylum level, the dominant microflora in the ileum of male SD rats were Firmicutes and Actinobacteria, accounting for more than 98%. The dominant colonic microbial community were mainly Firmicutes and Bacteroidetes, accounting for more than 95%. At the genus level, Lactobacillus and Alistipes were the predominant bacteria in the ileum. The colon was dominated by Lactobacillus and Romboutsia. In terms of flora diversity, the alpha diversity of colonic flora including richness index (Chao1 index) and diversity index (Shannon index) were significantly higher than those of ileum (P < 0.01), and the structural variability of the composition of its flora species was smaller than that of ileum; the ileal flora with significant structural variability were mainly of the phylum Firmicutes, Romboutsia, Peptostreptococcaceae, while the colonic flora had significant structural differences in Bacteroidales. In terms of flora function, the ileal flora dominant genes were significantly enriched in lipid-like metabolism, polyketide metabolism, membrane transport, biodegradation and other pathways, while the colonic flora dominant genes were significantly enriched in glycan biosynthesis metabolism, energy metabolism, biosynthesis of cofactor and vitamins and other products, and other pathways. Conclusion There are significant differences in structure and abundance between the ileal and colonic flora of SPF male SD rats, and the abundance and diversity of colonic flora are higher than those of ileal flora.

Objective To explore the histological characteristics of the kidney in Mongolian gerbils of different ages. Methods Ten Mongolian gerbils of 2, 6, and 12 months old (half male and half female) were selected. After euthanasia, the kidneys were taken and paraffin sections were made. After HE, MASSON and PAS staining, the structural differences of different parts of the kidney tissue in gerbils of different ages were observed by digital scanning, and the relevant data of the kidney tissue were measured by image analysis software. Results The number of proximal convoluted tubules was more than that of distal convoluted tubules in the renal cortex and outer medulla of gerbils. With age, the glomerular density decreased, the glomerular diameter increased, the basement membrane of renal tubules thickened, and the fibrous components between renal tubules increased. Conclusion The histological structure of Mongolian gerbil's kidney varies with age, which may be related to glomerulosclerosis and parenchymal cell reduction. The specific mechanism needs further study.

Objective Focused on the laboratory animal domestication and breeding of domestic cats, to explore the feeding management methods and breeding techniques of experimental cats. Methods Seven Chinese garden cats from three litters were introduced from the rural suburbs of Guangzhou, and a breeding seed colony was established. The cats were domesticated in captivity, bred, closed breeding and transmission according to the feeding and management methods of laboratory animal. The population reproduction, the number of pregnancies per year, the litter season, the birth and weaning quality of the cats, and the survival rate of weaning were statistically collected. Results The young breeding cats were able to adapt to the cage feeding management. In the transmission breeding and the expanded breeding colony, the number of female cats pregnant with one, two or three litters a year accounted for 63.2%, 26.3% and 10.5%, respectively. The proportions of litters born from the 1st to the 4th quarters were 20.7%, 20.7%, 27.6%, and 31.0%. A total of 29 pregnancies and 101 kittens were got from 19 female cats, with an average of (3.5±1.33) kittens per litter. The birth weights of female and male cats were (89.31±13.69) g and (93.47±15.12) g, respectively. Sixty-seven kittens survived from weaning. The average survival rate was 60.86%, and the weaning weights of female and male cats were (361.62±82.77) g and (376.0±91.71) g, respectively. Conclusion Domestic Chinese garden cats can adapt to laboratory animal feeding and breeding rules, and have strong fertility. They can normally pregnant and breeding throughout the year. The kittens grow to 5-6 months of age can meet the weight requirements for the examination of pharmaceutical hypotensive substances, and can be used as experimental cats for pharmaceutical examination with clear origin.

Objective To investigate anatomical characteristics and background lesions in laboratory British-shorthair cats (BSCs) through gross and histopathological examination, and provide effective basis for the research and application, standard establishment and market promotion of this experimental animal. Methods Gross system dissection and histopathological examination were performed on 14 adult BSCs (half male and half female), and the histological characteristics and background pathological data were collected and analyzed. Results The body weight and organ index of spleen of BSCs was higher in males than females (P < 0.05, P < 0.01), the organ coefficients of brain and thymus in BSCs were lower in males than females (P < 0.05). The anatomical structure of testicles, heart, thyroid gland and tentorium of BSCs is different from that of rodents and canine. Furthermore, histopathological examinations revealed that the structures of heart, pancreas, spleen in BSCs differed from two experimental animals mentioned above. In addition, there were multiple hepatic cell vacuolar degeneration in BSCs (9/14), and occasional renal, brain and lymphoid tissues were also found in some animals. Conclusion There were six differences in body weight, and organ-coefficient of spleen, thymus, and brain in BSCs, while the hepatocyte phospholipidosis of liver and background lesion in BSCs were found.

The host digestive tract comprises trillions of commensal microbes, collectively called microbiota. These microbes interact with a various host cell types and have a significant impact on health and disease. High-throughput sequencing technologies have accelerated the identification of numerous poorly studied microbes associated with health and disease. Genetic and humanized mouse models with and without environmental exposure were established to study the roles of these microbes in human physiologies and pathologies. Important findings related to the microbiota, mucosal immunity, and infectious diseases in mouse models are summarized. Furthermore, challenges and opportunities in leveraging genetic approaches and environmental exposure to optimize mouse models are discussed.

Chinese hamsters are experimental animals originally from China. They play an important role in experimental research on medicine and biology. They are widely used in life science research, such as genetics, infectious diseases, tissue culture, especially in animal models and mechanism research, such as diabetes and oral cancer. This paper reviews the relevant applied studies of Chinese hamsters in disease animal models since its development, and discusses the advantages and problems associated with the use of these animals in biomedical research.

Objective To establish an effective method of isolation and primary culture method for microvascular endothelial cells derived from the spinal cord of tree shrews in vitro. Enterovirus 71 (EV71) was used to infect these cells to explore its infectious characteristics and provide a reference for the study of the mechanism of EV71 induced damage to the central nervous system. Methods The spinal cord tissues were digested twice with type Ⅱ collagenase, dispase, and DNaseⅠ, then the microvascular endothelial cells were obtained. EV71 was used to infect tree shrew spinal microvascular endothelial cells, and the virus titer at different time points was measured. The expression of EV71 in the infected cells was detected by immunofluorescence assay to determine the infectivity of EV71 to the spinal cord microvascular endothelial cells of tree shrews. Results The microvascular endothelial cells were typically branched and beaded, and the passage cells obtained after puromycin purification and culture were mainly irregular polygonal cells. The cellular immunofluorescence results showed that CD31 and vWF expressions were positive. The spinal microvascular endothelial cells of tree shrews were infected with EV71 at a multiplicity of infection of 1, the cells showed typical cytopathic appearance, and the virus titer was approximately 3.2×10 ⁶ TCID ₅₀/mL. This proved that EV71 infected and proliferated in the tree shrew spinal cord microvascular endothelial cells, and within 48 h, the viral load in the supernatant increased linearly, reaching its peak at 12 h. The indirect immunofluorescence method detected virus particles in the cytoplasm of the cells 12 h after infection. Conclusions The isolation and purification methods of spinal cord microvascular endothelial cells from tree shrews are successfully established, and the infectivity to the obtained cells and proliferation of EV71 in the cells are confirmed, providing a basis for the study of the mechanism of EV71 invading the central nervous system.

Objective To determine and compare the hematological indexes (blood biochemical and physiological indexes) and the percentage of lymphocyte subsets in immunodeficient mice, providing basic data for tumor and immunology research applications. Methods (1) A total of 4 immunodeficient mouse strains, BALB/cA-nude, SCID, NOD-SCID, and NPSG, were included. Twenty mice (6-week-old, half male and half female) were analyzed. Blood biochemical (25 items) and physiological indexes (30 items) were determined and compared with those of BALB/cA-nude mice of the same age. (2) Four strains of immunodeficient mice, 4 mice (6-week-old, half male and half female) were randomly selected and analyzed with flow cytometry. Their symphocyte subsets were compared with those of BALB/cA-nude mice of the same age. Results (1) The white blood cell (WBC) count, lymphocyte (LYMPH) count, lymphocyte percentage (LYMPH%), and neutrophil count of immunodeficient mice were lower than those of BALB/cA mice ( P<0.01). In contrast, the neutrophil percentage (NEUT%) and reticulocyte count were higher than those of BALB/cA mice ( P<0.05, P<0.01). Furthermore, the levels of WBC, LYMPH and LYMPH% of SCID, NOD-SCID, and NPSG mice were significantly lower than those of BALB/cA-nude mice, while NEUT% was higher than that of BALB/cA-nude mice ( P<0.05). (2) The blood glucose and triglyceride levels in NOD-SCID and NPSG mice were lower than those in BALB/cA mice ( P<0.01), while uric acid level was higher than that of BALB/cA mice ( P<0.05). (3) BALB/cA mice had no T cells and low activity of B cells and natural killer (NK) cells. SCID and NOD-SCID mice had no T cells and lower activity of B cells and NK cells than BALB/cA-nude mice. NPSG mice had no T, B, and NK cells. Conclusion The blood biochemical and physiological indexes and the percentage of blood lymphocyte subsets in BALB/cA-nude, SCID, NOD-SCID and NPSG mice are consistent with the characteristics of corresponding immunodeficient mouse strains.

In this paper,we elaborated the importance of specific pathogen-free (SPF) pigs for prevention and control of livestock and poultry disease and the research status at home and abroad,analyzed the existing problems,introduced the common breed methods of SPF pig population,and discussed the application prospect of SPF pigs.The aim of this paper is to provide some theoretical guidance for the development of experimental animals on animal disease prevention and control research.

Objective To determinate the main organ weights,blood physiological and biochemical indexes,immunoglobulins,complements and immune cells data of SCID mice. Methods Twenty SCID mice at the age of 4,8 and 16 weeks old respectively,with half male and female,were selected for detecting the main organ weight,blood physiology and biochemistry indexes,immunoglobulins and complements data.Twenty SCID mice at the age of 8 weeks old,with half male and female,were selected for detecting T cells and subgroups,B cells,and NK cells. Results The thymus weight of SCID mice was independent of gender and age,and there was no significant difference.The levels of red blood cell,lymphocyte,IgG,IgA and IgM in the 4-week-old SCID mice were significantly greater than those in 8 weeks and 16 weeks.T cells,B cells,and NK cells,separated and sampled from spleen,are no significant difference in gender.CD3+ was the smallest proportion in total immune cells,and B220+ accounted for the largest proportion. Conclusions SCID mice are immunodeficiency animals of T and B cells comprised.The blood physiological and biochemical data of this experiment were basically consistent with the data of SCID mice abroad.It shows that the biological characteristics,such as heredity character,physiology biochemistry of this strain have not changed since the introduction.

Objective To obesrve the correlation between blood lipids and insulin resistance in obese rats induced by high-fat diet. Methods Male Sprague-Dawley rats were continuously fed with high fat diet supplemented with 36% fat energy for 12 weeks. The food intake, body weight were detected, Lee's index was calculated, serum which was collected by multiple time periods and the degrees of serum insulin, fasting blood glucose, total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol(HDL-C) and low density lipoprotein cholesterol (LDL-C) were measured, and insulin resistance index was calculated. Cluster analysis was used to screen successful insulin resistance rats and their differences in body weight, Lee's index, biochemical indicators compared to normal groups were analysed. Result Rats induced by high-fat diet developed obesity after 4 weeks with higher levels of body weight and Lee's index ( P<0.01, P<0.05). Sixteen rats producing insulin resistance were selected by cluster analysis based on the 12-week insulin resistance index of obese rats. After statistical analysis, 16 rats developed insulin resistance after 8 weeks, with lower levels of TC and HDL-C as compared with the normal group ( P<0.05). But there was no significant change in FBG, TG and LDL-C contents. Conclusion Obese rats induced by 36% fat-energy high-fat diet began to produce insulin resistance with about 50% of the obese rats at the end of the 8th week and the lipid metabolism were significantly disordered in insulin resistance rat.

Objective To study sexual and age differences of hematological and blood biochemical values in laboratory British-shorthair cats and to provide the basis for the cat related research. Methods Hematological parameters and blood biochemical indices of laboratory British-shorthair cats at 5 month old and 11 month old were measured, and the results were compared according to age and gender. Results There were age-related difference in 2 hematological indicators of female cats[hemoglobin(HGB), hematocrit(HCT)and in 5 indicators of male cats[HCT, mean corpuscular volume(MCV), erythrocyte(RBC), HGB, and mean corpsular hemoglobin(MCH)]. Sexual difference were observed in 2 hematological data [leukocyte(WBC), lymphocyte(LYMPH)from 5 month old cats and in 3 hematological data(RBC, HGB, LYMPH%) from 11 month old cats. Among the blood biochemical values, age-related difference exist in 4 parameters of female cats[alkaline phosphatase (ALKP), phosphorus(PHOS), cholesterol (CHOL) and creatinine(CREA)]as well as in 3 parameters of male cats(ALKP, PHOS, CREA), gender effect were also observed on CHOL of female cats and on 3 variables of male cats[albumin(ALB), CREA and alanine aminotransferase(ALT)]. Conclusion There are gender difference in some hematological and biochemical values of laboratory British-shorthair cat both in 5 month old and in 11 month old, as well as age-related difference between 5 month old cats and 11 month old cats. Our finding indicate that effects of gender and age should be taken into consideration in establishing hematological and biochemical reference intervals of laboratory British-shorthair cat.

Objective To find out the genetic variation and differentiation of the I~IV generations in tree shrews ( Tupaia belangeri chinensis),and provide genetic bases for closed colony tree shrews. Methods The forty-nine genomic DNA of blood samples were extracted from I~IV generations tree shrews,the amplification products were detected by capillary electrophoresis and marked with fluorescent tags (FAM) PCR,then the genetic diversity of the tree shrew colony was analyzed comparatively using POPGENE,FSTAT software with tree shrews 18 microsatellite loci. Results The 89 alleles were found in the tree shrew colony,the average effective number of alleles,observed heterozygosity,expected heterozygosity,polymorphism information content,Shannon information index and allele richness were 3.779,0.523,0.613,0.558,1.277 and 2.938 respectively.The mean value of Fst was 0.046 in the colony.The genetic distance and unbiased genetic distance were 0.049~0.159 and 0.022~0.109 respectively. Conclusions The closed clony tree shrew shows high genetic diversity,and there was no significant difference in genetic diversity and differentiation.

Objective To analyze genetic diversity and relationship of two closed colonies of SD rats from Beijing and Shanghai respectively. Methods Seven microsatellite loci were tested by Hardy-Weinberg equilibrium (Hardy-Weinberg equilibrium,HWE),meanwhile,the values of the allele frequency,gene heterozygosity,polymorphic information content (PIC),the genetic distance and some other indexes were counted. Results The average number of observed alleles are 4.857 1 and 5.142 9 in two colonies respectively.The average observed heterozygosity were 0.647 6 and 0.585 7,the average PIC were 0.644 5,0.667 6 respectively.Three and two loci showed evident deviation from that of the HWE ( P<0.05) in SD rat colony from Beijing and Shanghai respectively.The unbiased genetic distance of the two colonies was 0.158 2 (Nei 1978). Conclusion The genetic diversity of SD rat colonies from Beijing and Shanghai are relatively rich.There are medium level of genetic differentiation between the two colonies.Microsatellite marker technique is an effective mean for genetic monitoring for closed clolony of SD rats.

Objective To establish a zebrafish model for real-time monotoring the development of melanoma in vivo and screening relative drugs. Methods The expression effect of pMITFa1-RedV12/hRas plasmid,in which the melanoma was labeled by red fluorescent protein (RFP),was verified in mouse B16 melanocytes.After microinjecting pMITFa1-RedV12/hRas into 1- cell stage of fertilized eggs of zebrafish,we monitored the process of melanoma formation with in vivo imaging system in zebrafish. Results pMITFa1-RedV12/hRas was successfully expressed in mouse melanoma B16 cells.Three days after microinjection of pMITFa1-RedV12/hRas vector to 1-cell satge of zebrafish,melanomas labeled by RFP protein was observed under the fluorescence microscope.Eight weeks later,melanomas were observed clearly by eyes.The rate of tumor formation was 100%.When microinjected into pMITFa1-RedV12/hRas vector into fertilized eggs of TG(zlyz:EGFP) transgenic zebrafish,the interaction between the melanoma cells labeled by RFP protein and the macrophages labeled by green fluorescent protein was clearly observed in in vivo imaging system. Conclusion Successfully established a zebrafish model for real-time monitoring melanoma in vivo,which is cheap and easy to operate.

Objective To investigate a dynamic curve of blood biochemical and physiological characteristics in the process of inbreeding ischemia-prone gerbil,and to provide basic data for inbred animal breeding. Methods The 17 blood biochemical and 22 physiological indices of blood samples from inbred 11th to 20th generation (F11 to F20) were detectioned by Beckman automatic biochemical analyzer (CX5) and Japanese photoelectric automatic blood cell analyzer (MEK-7222K). Results The results showed that the uricacidcrystal (URIC),lactate dehydrogenase (LD),creatine kinase (CK),alanine aminotransferase (ALT),high density lipoproteins (HDLD),magnesium (MG),red blood cell (RBC),leukocyte (WBC),eosinophil (EOS),neutrophil count (NEUT),monocytes (MON),basophilic granulocyte(BAS),blood platelet (PLT),thrombocytocrit (PCT),platelet distribution width (PDW),hemoglobin(HGB),mean corpuscular hemoglobin (MCH),and red blood cell distribution width (RDW) of F11-20 gerbil were increasing.The lymphocyte (LYM),creatinine (CRE),blood urea nitrogen (BUN),alkaline phosphatase (ALP),glucose (GLU) showed a decreasing trend.The hematocrit (HCT),mean corpuscular volume (MCV),mean corpuscular hemoglobin concentration (MCHC),average platelet volume (MPV) value was stable.The majority of indicators tend to be stable after F17. Conclusion The gerbil inbred strain has a certain influence on the most of the blood physiological and biochemical indices.

Objective To investigate the growth and reproductive performance of CMU/1 and CMU/2 ischemia-prone inbred gerbils;And to provide the data support for its’application,conservation and breeding. Methods The generations F20~F22 of 2 gerbil lines were selected and bred in accordance with inbreed Mating rule.The litter interval,the number of birth,the number of weaned pups and the growth curve of the 1~5 litters was analyzed. Results The birth weight of CMU/1 and CMU/2 was 2.5 g to 3.4 g.The litter size ranged from at least 1 to the most 9.The survival rate of weaned litter from 65% to 75%.The shortest litter interval was 14 days,whereas the longest 171 days.The weight gain at 2 to 6 week of age was more rapid. Conclusion There is significant difference in litter size between CMU/1 and CMU/2 ischemia-prone inbred gerbil.Most of them display birth intervals in the 21~70 day.Genotype seems have no effect on the reproductive characteristics of ischemia-prone inbred gerbils.

Objective To detect and compare the differences of coagulation factors between inbred gerbil CMU/1 and CMU/2,inbred rat F344,and inbred mouse BALB/c;then to analyze the characteristics of inbred ischemia-prone gerbil. Methods The four channel blood coagulation analyzer was used to determine three kinds of inbred animals’plasma prothrombin time (PT),activated partial thromboplastin time (APTT),fibrinogen (FIB),and thrombin time (TT).The SPSS23.0 software was applied for statistical analysis of data. Results The APTT FIB of CMU/1 and the FIB of CMU/2 of ischemia-prone gerbil displayed high standard deviation.The PT and FIB of CMU/1 and CMU/2 showed significantly different compared with that of F344 rat.The APTT of both ischemia-prone inbred gerbil lines demonstrated significant difference compared with BALB/c mouse and F344 rat. Conclusion The 4 coagulation factors of ischemia-prone inbred gerbil lines are consistent with those of inbred BALB/c mouse;which are significantly different from those of inbred F344 rat.

Microtus fortis which has the characteristics of natural resistance to Schistosoma japonicum,has been developed as a unique model animal for schistosomiasis resistance in China.It can also be used as a model animal for the study of diabetes,ovarian cancer and nonalcoholic fatty liver.In this paper,the classification,distribution,morphology and biological characteristics of Microtus fortis were reviewed,and the progresses of the study on the animal models of schistosomiasis,diabetes,ovarian cancer and nonalcoholic fat were summarized.

Objective To probe the causes of low reproductive performance in spontaneous dwarfism Wistar rats (SDWR). Methods A Wistar rat control group and a SDWR group both included 50 female and 50 male rats aged 12 weeks respectively, and were mated 1∶1 (male to female); the pregnancy rate, litter size, litter birth weight, weaning rate and weaning weight of the SDWR and Wistar rats were measured from the first parity to the fourth. Twenty female SDWR aged 8 weeks and 20 female Wistar rats aged 5 weeks were selected respectively to evaluate puberty and estrous cycle by vaginal cytology. Twenty female SDWR and 20 female Wistar rats aged 6-8 weeks were respectively injected intraperitoneally with 200 U/kg, 300 U/kg and 400 U/kg of pregnant mare serum gonadotropin (PMSG) plus human chorionic gonadotropin (hCG) for superovulation, and the ovulation induction effects. Twenty Wistar, 20 SDWR and 20 SDWR superovulation rats aged 6-8 weeks were compared in morphological changes of ovarian tissue by HE staining. Results The pregnancy rate, litter size, litter birth weight, weaning weight and weaning rate of the first parity to the fourth of the SDWR group were significantly lower than those of the Wistar group ( P<0.05). In the SDWR group, sexual maturation [(12.15 ± 0.81) weeks] was significantly delayed compared with the Wistar group [(8.05±0.76) weeks]. The Wistar group maintained a regular estrous cycle of 4-5 days, while the SDWR group showed an extended and disordered estrous cycle of 7-8 days, shortened estrous and extended metestrus. The results of superovulation test showed that the number of eggs in the SDWR group was significantly lower than that in the Wistar group ( P<0.01). The results of HE staining of ovarian tissue showed that in the Wistar group, follicles at all levels were growing actively, and granular cells and corpus luteum structure were normal; while in the SDWR group, the number of total ovarian follicles and follicles at all levels were significantly reduced, and granular cells was disarranged. Conclusion The low reproductive rate of SDWR may be related to delayed sexual maturity, prolonged and disordered estrous cycle, and ovarian dysfunction.

Objective Tg2576 transgenic mice with C57BL/6 and SJL hybridization background, which are commonly used in research of Alzheimer’s disease (AD), were used to investigate the potential effect of long-term breeding on the phenotype of AD. Methods Utilizing Morris water maze, immunohistochemistry, ELISA and immunofluorescence, the behavior and pathological phenotype of AD were studied in these Tg2576 mice which were introduced and bred in our laboratory for a long time. Results With the age increase, the learning and memory ability of in these Tg2576 mice was still significantly decreased. The typical beta amyloid (Aβ) deposition was also found in the cerebral cortex of these mice by immunohistochemistry. The content of Aβ in brain tissue was significantly higher than that in control mice. In addtion, the immunofluorescence analysis indicated that a large number of astrocytes gathered around Aβ plaques in the cerebral cortex. Conclusion The long-term bred of Tg2576 mice still have the typical clinical and pathological characteristics of AD mice.

Objective To establish genetic quality standard of inbred Chinese hamster ( Cricetulus griseus). Methods Based on investigating a large number of related literatures, according to Laboratory animal-Genetic quality control of mammalian laboratory animals (GB14923-2010) and the theory of population genetics, the genetic quality standard of inbred Chinese hamster was established. The genetic quality of Chinese hamster was detected by microsatellite markers which were obtained from a Chinese hamster genomic enrichment library and the PCR primers of them were designed. Results The genetic quality standard and the detection method of inbred Chinese hamster were preliminarily established. Conclusion The establishment of genetic quality standard of inbred Chinese hamster will standardize the breeding and reproduction of inbred Chinese hamster and promote the further improvement of genetic quality standard system of laboratory animals in China.

Animal model is an important method to study the mechanism of human disease, to screen drug, and to evaluate the safety and efficacy of drugs. With the development of molecular biology technology and the study of molecular genetic mechanism of human diseases, it is difficult to study the complex symptoms of human diseases in biomedical research using rodents as a result of the differences in genetic background, physiological and metabolic characteristics between rodent and human, the limitation of rodent in life science research is increasingly prominent. Primates play an irreplaceable role in biomedical research due to its evolution and biological characteristics. However, the limitation of genetic manipulation, long breeding cycle and high cost restrict the application of primates in biomedical research. The evolution of tree shrews are more closer to the primate than rodents. Tree shrews has been increasingly applied in the field of biomedical research since its characteristics of easy breeding, fast reproduction, the low cost and the key factors of neurological dysfunction and infectious diseases are conservative compared with primates. Based on the characteristics of physiological metabolic process and anatomical structure of tree shrews, this paper analyzes the advantages and problems of tree shrew in biomedical research.

Objective To establish high-quality SPF golden hamster colonies in accordance with WHO pre-certification of live attenuated Japanese Encephalitis Vaccine. Methods A new SPF golden hamster colony was established by caesarean based on the established mating method. The colonies were under general quality control with regular sampling tests. Results The foundation stocks and production stocks of SPF golden hamsters were established, which were negative in 19 virological items、6 parasitological items and 17 bacteriological items. Conclusion A new SPF golden hamster colony is successfully established, the quality meets the requirements of WHO TRS 980.

Genetically modified (GM) rabbits have been proved to be excellent animal models for biomedical research. GM rabbits expressing human genes have been widely used as models for cardiovascular disease, AIDS, and cancer research. So far, GM rabbits were almost generated by pronuclear microinjection, which randomly leads to additive genes integrated in the rabbit genome. Compared to this technology, gene targeting in ES cells is more powerful tool for deepening understanding of gene function. However, the rabbit lack stable ES cell lines. Thus, gene targeting, dependent on ES cells, is not possible used in rabbit. Instead, RNA interference is quickly becoming a valuable experimental tool that allows investigators to knock down the expression of specific genes, and makes it possible to create GM rabbit models. Recently, with the advent of novel genetic technologies, such as Zinc-finger nucleases, transcription-activator like effector nuclease, the RNA-guided CRISPR-Cas endonuclease, there have been a significant breakthroughs in gene targeting of rabbit. Researchers have successfully created some gene knock out rabbits using Zinc-finger nucleases, or transcription-activator like effector nuclease, or the RNA-guided CRISPR-Cas endonuclease. Based on our study in the area of GM rabbits, in this paper, we review the progress of GM technology in rabbits during the past years and emphasize their applications as a model in biomedicine.

Objective To observe the microstructure characteristics of spleen at different ages of SD rats. Methods Seven rats were randomly sampled from a same cohort of normal male SD rats at different growing stages (1 day and 1, 2, 3, 6,12, 24 and 36 months of age). The tissue blocks from whole spleens were taken to make the methyl acrylic resin embedded sections. After the sections were stained with periodic acid-Schiff's reagent and hematoxylin, the microstructure characteristics were observed. Result There was no obvious structure at 1 day, the spleen was composed of dense cells, including the splenic cord and the periarteriolar lymphoid sheath. At 1 month of age, the splenic sinus was formed generally and the boundary was not obvious with splenic cord, and the marginal zone was clearly and megakaryocytes were plents. For the 2 months, the splenic follicle was formed, all key structures had been formed and the capsule was thickening. For the rats of 3 to 12 months, the percentages of the white pulp and the red pulp in the spleen became stable. For the rats of 24 to 36 months, all structure's boundary were blurred. Conclusion The development of structure in rat spleens is characterized of a continuous, establishing, improving and regressing process. The rat spleen grows fully before second month.

Objective To compare the genetic backgrounds of C57BL/6J and 129/SvJ and the behavioral phenotypes with their hybrid (F1) mice. Methods C57BL/6J and 129/SvJ were cross mated and bred to obtain two F1 (129B6F1 and B6129F1). These F1 mice with C57BL/6J and 129/SvJ were divided into 8 groups of experimental mice according to different gender. Numbers of mice in each group were no less than 12. Behavioral studies such as the open field test, the tail suspension test, the morris water maze, the passive avoidance test, the hot plate were conducted to compare the behavioral performance of C57BL/6J, 129/SvJ and F1 from the paramters of anxiety, depression, learning and memory, and heat pain response respectively. Results Compared with 129/SvJ, F1 had significant difference in peripheral and marginal activities in the open field activities ( P<0.01). There was no significant difference in the behavior of F1 and parent mice in the tail suspension activities. Compared with C57BL/6J, the latency of finding the platform and entering the dark box of F1 were significantly different in the morris water maze and the passive avoidance activities ( P<0.05). Conclusion Different behavior phenotypes of F1 are influenced by different genetic backgrounds of their parents.

Objective To study the incidence of spontaneous histopathological lesions of young SPF SD rats at different growth and development stages, to provide information for drug nonclinical safety evaluation especially for pediatric drugs. Methods The samples were collected from SD rats in day 51 (PND51), day 65 (PND65), day 111 (PND111) and day 139 (PND139) after born as control groups in safety evaluation studies in recent 2 years. The pathological sections and histomorphological features of SD rats were observed under an optical microscope, and the incidence of pathological changes was also observed. Result The spontaneous lesions of young SPF SD rats at different times were analyzed and reported. The high incidence lesions occurred mainly in heart, liver, kidney and other organ lesions. The incidence and levels of spontaneous histopathological lesions of liver, heart and kidney were increased and developed with the rats growing. Conclusion The spontaneous lesions and their incidence in young SPF SD rats in drug toxicology research can provide some reference for relevant scientist.

Objective To reveal the physiological changes of blood vessels in different growth stages of spontaneous hypertensive rats (SHR) by measuring the pulse wave velocity (PWV) and analyzing the structure of aortic media cross-sectional area (MCSA) in the same period of SHR. Methods Color Doppler ultrasonography and vascular pathological analysis were used to determine PWV and MCSA of SHR at 4, 6, 8, 10 and 12 month of age. Results The PWV of 12-month-old SHR was significantly higher than that of 8-month-old, 6-month-old and 4-month-old SHR respectively( P<0.05). The PWV of 10-month-old SHR was significantly higher than that of 6-month-old and 4-month-old SHR respectively ( P<0.05). Meanwhile, the MCSA analysis of SHR showed that the aortic MCSA of SHR increased gradually with age. Conclusion With the increase of age, the arterial compliance of SHR is worse, the vascular elasticity is decreased, and the degree of atherosclerosis is enhanced.

Objective To determine the main nutritional components of SPF golden hamster milk and compare with other rodents milk (mice, rats, guinea pigs), rabbit milk, cow milk and infant formula milk. Methods According to the national standard, the essential nutrients of golden hamster milk were detected by Kjeldahl and ICP-MS. The content of amino acids was detected by an automatic amino acid analyzer. Results The main nutrient contents of 100 g golden hamster milk were as follows: water 86.4 g, protein 6.94 g, fat 2.70 g, lactose 2.21 g, mineral elements calcium 120.00 mg, magnesium 20.10 mg, phosphorus 82.05 mg, zinc 1.470 mg, etc. The total content of hydrolyzed amino acids was 61mg/g, and the content of essential amino acids was 24.4 mg/g, accounting for 0.4 of the total amount of amino acids. Conclusion The milk of golden hamster is characterized by high protein, low fat and low lactose, which provides a scientific basis for the formulation of sterile golden hamster formula milk.

Objective    To observe the occurrence of spontaneous tumors in SD rats, and to provide the background data for carrying out new drug induction trials. Methods    In a carcinogenicity test, 120 normal SD rats (SPF-grade) at 4 weeks of age were divided into male and female with the same number. All rats were observed for one week before the experiment. After 104 weeks of conventional feeding, the sedation was performed. The dead rats during the experiment and the sacrificed rats were dissected. The organs such as heart, lung, liver, spleen, kidney, adrenal gland, thymus, brain, testis and epididymis (or uterus) were weighed, and the types and incidence of spontaneous tumors in each organ were observed by an optical microscope after routine pathology. Results    A total of 113 SD rats were observed (7 rats were lost during the test), the tumor-bearing rats accounted for 66.4% (75/113), of which the benign tumors accounted for 48.7% (55/113), and the malignant tumors accounted for 17.7% (20/113). Tumors occurred in 49.1% (28/57) of male rats, of which 50.9% (26/57) were benign tumors, and 3.5% (2/57) were malignant tumors; the benign tumors were mainly pituitary adenomas (36.8%) and adrenal medulla tumor (7.0%), the malignant tumors were mainly thyroid adenocarcinoma (1.8%) and fibrosarcoma (1.8%). Female rats had tumors of 83.9% (47/56), of which the benign tumors accounted for 51.8% (29/56), and the malignant tumors were 32.1% (18/56); the benign tumors were mainly pituitary adenomas (50.0%), breast fibrous glands tumors (12.5%) and breast adenomas (12.5%), the malignant tumors were mainly breast adenocarcinoma (25.0%) and fibrosarcoma (3.6%). Conclusion    The incidence of spontaneous tumors was higher in more than 2 years old SD rats, and the incidence of benign tumors was higher than that of malignant tumors, which may be related to aging, tumors and individual differences. 

Objective To characterize and to compare the growth and reproductive performance of Microtus fortis of Dongtinghu stock ( M.f.calamorum) and Qingtongxia stock ( M.f.fortis). Methods Females and males of each stock,aged about 10 weeks,were long-term monogamously mated,the reproductive characters were analyzed.Body weight of 60 Microtus fortis (30 females and 30 males) of each stock were measured from born to 98 days of age,and the growth curves were fitted by 3 nonlinear growth models. Results For Microtus fortis of dongtinghu stock,average litter size was 4.70 ±1.15,litter interval was (30.78 ±10.21) d,weight at birth and weaning was (4.09±0.13) g and (27.31±1.10) g respectively.For Microtus fortis of qingtongxia stock,average litter size was 3.58±1.00,litter interval was (35.60±12.48) d,weight at birth and weaning was (4.37±0.09) g and (28.22±0.46) g respectively.Growth curve showed that the sexual dimorphism of Dongtinghu Microtus fortis and Qingtongxia Microtus fortis occurred at 14 d and 28 d respectively.The fitting results showed that the females had earlier time of inflection than that of males. Conclusion The reproductive capacity of Microtus fortis in Dongtinghu stock is higher than that of Qingtongxia stock.The body weight of male and female has significant dimorphic in both stocks.Femals reached sexual maturity earlier than males.

Objective To establish genetic monitoring method by biochemical markers for inbred gerbils and apply it in analyzing the homogenous of the ischemia-prone inbred gerbil lines CMU/1 and CMU/2. Methods Twenty-six biochemical marker loci were selected to perform cellulose acetate fiber electrophoresis for several kinds of gerbil tissues by optimum electrophoresis conditions referred to previous report and optimized the sample treatment and staining method. Then these methods were used in detecting homogeneous of 2 inbred lines CMU/1 (77 gerbils) and CMU/2 (44 gerbils) genetic quality involved generation F21-F23. Results All of 26 biochemical marker loci could be detected successfully in both inbred gerbil of 121 gerbils. Thereinto, 24 loci exhibited monomorphism within and between CMU/1 and CMU/2. However, the loci Es-3 and Es-4 showed polymorphism between two strains. Conclusion The biochemical marker method for genetic monitoring of inbred gerbil has been successfully established. The 26 biochemical marker loci for inbred gerbil strain CMU/1 and CMU/2 has been confirmed which homogeneous reached to 100%. These data indicated that two inbred strains match the standard of inbred laboratory animals (GB14923-2010).