Colorectal cancer (CRC) is the third most common malignant tumor in the world. The latest statistics show that CRC accounts for 10% of all cancer cases worldwide and is the second leading cause of cancer deaths. CRC is a highly heterogeneous disease, the development of which is driven by functional abnormalities or epigenetic changes caused by multiple gene expression mutations, and there are different pathways that lead to tumor formation. Complex factors such as genetics, environment, ethics, and individual differences of patients themselves limit the study of CRC in humans, so the disease animal models have become an indispensable tool for the study of CRC, and play an important role in prevention, treatment, preclinical research and basic research. There are various types of CRC animal models, of which mouse models are the most widely used. According to different model establishing methods, the models are divided into spontaneous, chemically induced, transplanted tumor and genetic-engineering mouse models. Different models have different characteristics and application prospects. In this study, we focus on these mouse models of CRC in detail, and introduce the latest research progress of CRC models in rats, experimental pigs and zebrafish, to provide reference for the selection and application of animal models of CRC.

As the incidence of male infertility has been increasing during recent years, it is urgent to reveal the pathogenesis of male infertility, as well as to develop the new drugs for treatment of male infertility, in order to solve the declining birth rate and aging problems. The construction and application of male infertile animal models is critical for drug development, which plays an important role in accurately evaluating the efficacy and mechanism of infertility treatment. A suitable infertility model not only can reduce the repeated drug efficacy evaluations, reduce animal usage and the cost of new drug development, but also has important reference value for subsequent clinical trial research. Male infertility laboratory animal models can be constructed through chemical, physical, endocrine, environmental estrogen, gene modification, and immune methods. This article mainly introduces the existing male infertility animal models available for drug development, and briefly introduces the application progress of each model to provide reference for the male infertility drug researchers.

ObjectiveConstruction of a negative control line for the Drosophila transgenic system based on ΦC31 integrase and vector plasmid pUASTattB to provide a more scientific negative control for transgenic Drosophila research experiments. MethodsThe vector plasmid pUASTattB was microinjected into four different genetic backgrounds Drosophila lines attP-25C6, attP-68A4, attP-75B1 and attP-86F8 embryos carrying ΦC31 integrase. All of the injected embryos were incubuated to get G0 adults, and each of them was crossed with balancer stock ywR13S separately in a single vial (1 adult of the G0 generation and 3 of the ywR13S in each vial). The probability of successful insertion was calculated by observing the colour of the compound eyes of the G1 generation of Drosophila to determine whether there was a mini-White insertion. The G1 generation Drosophila adults successfully inserted into mini-White were then selected to make single-vial crosses (one G1 generation male Drosophila crossed with three virgins of balancer Drosophila line) with each of the three balancer Drosophila strains DB, ywR13S and yw122, respectively, for balanced seed preservation. The genomic DNA of the conserved Drosophila lines was extracted and the vector plasmid pUASTattB was identified for transfer by PCR. Results12 Drosophila strains were obtained, all of which were red-eyedDrosophila melanogaster carrying the mini-White marker, and were identified by PCR as having the pUASTattB sequence insertion. ConclusionThe 12 transgenic Drosophila strains can meet the negative control requirements for the transgenic fly research experiments that constructed with pUASTattB as the vector basically, enriching the Drosophila resources in the National Drosophila Resource Center of China.

ObjectiveOptimize the latex perfusion technique and apply it to the construction of a murine craniofacial venous vascular model.Methods A total of nine 8-week-old male C57BL/6 mice weighing (25.0±1.3) g were randomly divided into three groups: 60% latex physiological saline group, 60% latex heparin group, and 30% latex heparin group. After completion of the perfusion, the specimens were immersed in 4 °C formalin fixative for 24 h, followed by dissection, observation, and measurement of the extracranial blood vessel diameters. Results After 200 μL latex perfusion solution was injected into the external jugular vein, the supraorbital vein, infraorbital vein, temporal vein, retrofacial vein, masseter vein and external jugular vein were perfused in each group.After comparing the perfusion degree of the distal branches of blood vessels, sublingual vein and tip venule, it was found that the 30% latex heparin group had the best perfusion effect, followed by the 60% latex heparin group, and the 60% latex saline group had the worst perfusion effect.ConclusionThe optimized latex perfusion technique can effectively infuse the veins in the head and face of mice, and this technique can provide a good reference for the study of the direction and morphology of facial veins in mice.

Objective The aim is to utilize CRISPR/Cas9 gene editing technology to construct Dmd gene mutant mice with a point mutation in exon 23 of the Dmd gene. Subsequently, the phenotypic changes of the mice in muscles and immune systems are analyzed and verified, providing an evaluation model for Duchenne muscular dystrophy and other related diseases.MethodsBased on the sequence characteristics of exon 23 of the Dmd gene, small guide RNA (sgRNA) was designed and synthesized. Cas9 mRNA, sgRNA fragments, and oligo donor DNA were microinjected into fertilized eggs of C57BL/6J mice. After transferring the fertilized eggs to surrogate mice, F0 generation mice were born. After mating with F0 generation mice, offspring mice were obtained, and Dmd gene positive mutant (Dmd^Mu/+) mice were obtained after genotype identification. Male hemizygous Dmd^Mu/+(Dmd^Mu/Y) mice were selected for phenotype validation. The body weight of live 3- and 9-month-old mice were recorded. Muscle tension was evaluated through the grid test. Hearts and semitendinosus muscles were collected, and the histopathological changes were observed using HE staining. Further, the expression of Dmd protein in muscle tissue of 9-month-old mice was analyzed by Western blotting.An acute inflammation model was established in Dmd^Mu/Y mice using lipopolysaccharide induction. Peripheral blood from the submandibular vein was collected, and the changes in the proportion of neutrophils and monocytes were detected by flow cytometry.Results The results of genome sequencing and Western blotting confirmed the successful construction of Dmd gene point mutant mice (Dmd^Mu/+ mice). Dmd protein expression was not detected in skeletal muscle and myocardium of Dmd^Mu/+ mice, and it was significantly reduced compared to wild-type C57BL/6J mice (P<0.05). Compared with wild-type mice of the same background, Dmd^Mu/Y mice at 3 and 9 months of age showed significant weight loss (P<0.01) and decreased muscle tension (P<0.05). 9-month-old Dmd^Mu/Y mice exhibited significant pathological changes in skeletal muscle and myocardium, including widening of intermuscular space. Under normal condition, compared with wild-type mice, the proportion of neutrophils and monocytes in the peripheral blood of 3-month-old Dmd^Mu/Y mice was significantly lower than that of wild-type mice (P<0.01). After lipopolysaccharide stimulation, the proportion of neutrophils in peripheral blood of 3-month-old Dmd^Mu/Y mice remained significantly lower compared to that of wild-type mice (P<0.01). The proportion of neutrophils in peripheral blood of 9-month-old Dmd^Mu/Y mice significantly decreased after lipopolysaccharide induction (P<0.01), with a trend of change observed in monocytes between groups.Conclusion The successful construction of the Dmd gene mutant mouse model has confirmed the vital function of Dmd gene in maintaining normal muscle tissue morphology and muscle tone. It preliminarily indicated that Dmd gene deletion could significantly reduce the proportion of neutrophils in peripheral blood, offering a new perspective for the study of immune system alterations in Duchenne muscular dystrophy patients.