Autophagy is a cellular degradation system in which cytoplasmic components including organelles are sequestered by double membrane structures called autophagosomes and sequestered materials are degraded by lysosomal hydrolases for supply of amino acids and for cellular homeostasis. The autophagy induced in response to nutrient deprivation is executed in a nonselective fashion, and adaptation to nutrient-poor conditions is the main purpose of autophagy. On the other hand, recent studies have shed light on another indispensable role for starvation-independent or constitutive autophagy in cellular homeostasis, which is mediated by selective degradation of a specific substrate(s). Herein, we introduce pathophysiological roles of starvation-induced, constitutive, and selective autophagy (in particular, selective turnover of p62 through autophagy) disclosed by autophagy-deficient mouse models.
Behavior has been proven to be extremely variable among human individuals. One of the most important factors for such variations of behavior is genetic diversity. A variety of mouse strains are reportedly suitable animal models for investigating the genetic basis of large individual differences in behavior. Laboratory strains have been shown to exhibit different behavioral traits due to variations in their genetic background. However, they show low-level genetic polymorphism because the original colony used for establishing the strains comprises a relatively small number of mice. Furthermore, because the laboratory strains were derived from fancy mice, they have lost the original behavioral phenotype of wild mice. Therefore, incorporation of inbred strains derived from wild mice of different mouse subspecies for behavioral studies is a marked advantage. In the long-term process of establishing a variety of wild-derived inbred strains from wild mice captured all over the world, a number of strains have been established. We previously identified a marked variety in behavioral traits using a Mishima battery. This review reports on the usefulness of wild-derived strains for genetic analyses of behavioral phenotypes in mice.
BCL11B/CTIP2 zinc-finger transcription factor is expressed in various types of cells in many different tissues. This study showed that BCL11B is expressed in the nucleus of the outer hair cells of the mouse cochlea, degeneration of which is known to cause deafness and presbycusis or age-related hearing loss (AHL). We tested whether or not Bcl11b heterozygosity would affect AHL in mice. Analysis of auditory brainstem responses revealed AHL in Bcl11b+/– heterozygous, but not wild-type, mice, which was evident as early as 3 months after birth. Histological abnormalities were observed in the outer hair cells of the Bcl11b+/– mice at 6 months of age with hearing loss. These results suggest that the AHL observed in Bcl11b+/– mice is the result of impairment of the outer hair cells and that BCL11B activity is required for the maintenance of outer hair cells and normal hearing.
The effects of levonorgestrel (LNG) on serum levels of reproductive hormones and their receptor mRNA expression in the ovary and uterus of Mongolian gerbils were examined. The results show that serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) increased, whereas serum estradiol (E2) and progesterone (P4) decreased profoundly after LNG treatment. LNG down-regulated the mRNA expression of follicle-stimulating hormone receptor (FSHR), luteinizing hormone receptor (LHR), estrogen receptor (ER) β and progesterone receptor (PR) in the ovary, and ERα and PR in the uterus of Mongolian gerbils. The down-regulated effects were time-dependent and dose-dependent. LNG had no obvious effects on ERα mRNA expression in the ovary. The findings suggest that LNG impairs reproductive hormone receptor expression at the molecular level in Mongolian gerbils. Also, the two ER subtypes may play different roles in the ovary, and ERβ may not be the predominant ER subtype in the uterus of Mongolian gerbils. The ovary and uterus may be the important sites of action of LNG through its direct progesterone-like effects in Mongolian gerbils.
Sprague-Dawley (SD) rats are broadly used in preclinical studies for drug development, so a lot of information for the rats can be obtained especially from pharmacokinetic, pharmacological and toxicological studies. The purpose of this study was to clarify whether SD rat skin can be used to predict human skin permeability. In vitro permeation studies of the three model drugs, nicorandil, isosorbide dinitrate, and flurbiprofen, through human skin and SD rat skin were performed using Franz-type diffusion cells. The permeation rates of the three model drugs through human skin and SD rat skin were determined, and their variations were evaluated. The inter-individual variations in SD rat skin permeability of the three model drugs were much lower than that in human skin permeability, although the permeation rates of the three model drugs through the SD rat skin were about twice those through human skin. In addition, no difference in the skin permeability coefficients of the three model drugs was obtained between fresh SD rat skin and frozen SD rat skin. The markedly smaller variation in the permeability through SD rat skin compared with that through human skin indicated that in vitro permeation studies using SD rat skin would be especially useful for evaluating differences in the skin permeability of the three model drugs as well as for predicting human skin permeability.
The aim of this study is to clarify the effect of low intensity pulsed ultrasound (LIPUS) on shortening of the fracture healing period and endochondral ossification during the fracture healing process. We first established a model of aging-related delayed union fractures consisting of aged mouse (C57BL/6J; 40 weeks old) with closed femur fractures. We compared the healing process of 40-week-old mice to the healing process of 8-week-old (young) mice using radiological and histological analysis. In aged mice, some cartilage formation was observed 10 days after the fracture; however, endochondral ossification and hard callus bridging were observed 21 and 28 days after the fracture, respectively, whereas cartilage remained in the callus on day 28, suggesting delayed endochondral ossification following bone remodeling. Meanwhile, in aged mice with LIPUS treatment, cartilage formation was similar to that in aged mice without LIPUS; however, hard callus bridging and bone remodeling were observed 21 and 28 days after fracture, respectively, suggesting that LIPUS shortened the healing period due to promotion of endochondral ossification. Immunohistochemical analysis showed marked expression of vascular endotherial growth factor and neovascularization in the fibrous tissue comprising the periosteum that surrounded the whole callus. A cell migration test involving primary cultured human endothelial cells also showed promotion of cell migration by LIPUS. These results suggested that endothelial cell migration and neovascularization, which were observed around fracture sites, played a part in the mechanism of promotion of endochondral ossification by LIPUS.
This study determined pathogenicity of an A11181G mtDNA mutation found in a senescence-accelerated mouse strain, SAMP8. The mutation was at a highly conserved site of the mt-Nd4 gene, which encodes one of the respiratory complex I subunits. The young SAMP8 expressed reduced complex I activity, which is controlled by both nuclear and mitochondrial DNA (mtDNA). To exclude the nuclear effects, we isolated transmitochondrial cybrids that share the same nuclear background, but possess mtDNA with or without the mutation. The cybrids showed normal respiratory function irrespective of whether their mtDNA possessed the mutation or not, suggesting that the A11181G mutation is not responsible for respiration defects found in SAMP8.
The genetic basis of the peripheral blood cell parameters is not fully elucidated. Thus, it is essential to research the correlation between blood cell counts levels and the genome in laboratory animals and subsequently in humans. In the present study, we examined 288 F2 mice from a cross between BALB/cW and C57BL/6J-Mplhlb219/J. The C57BL/6J-Mpl hlb219/J strain is a mouse model of thrombocytopenia. We found very strong correlations for PLT counts and revealed some highly significant correlations for RBC counts. On the basis of the obtained results, we presume that genetic control of erythrocyte parameters is divided into two pathways: first, the morphological determinants responsible for the red blood cell count (RBC), hematocrit (HCT), and mean corpuscular volume (MCV), and second, the functional pathway determining the hemoglobin content (HGB). The locus on Chromosome 4 is the only detected quantitative trait locus (QTL) influencing the analyzed platelets parameters. We also detected highly significant correlations for erythrocyte parameters on Chromosome 1 (RBC, MCV, MCH), Chr 7 (HGB), Chr 9 (MCHC), Chr 11 (RBC), and Chr 17 (MCH). Finally, with regards to the given correlations, using the Mouse Genome Database resource, we proposed candidate genes with possible meaning for the level of these parameters: cytokine receptor genes (e.g., Mpl), transcription factor genes (e.g., Xbp1, Ikzf1), hemoglobin chain genes (e.g., Hbb-b1, Hbb-ar), and many others localized in the confidence intervals of found QTLs.
We investigated sex determination via the ZFX and ZFY genes using PCR-RFLP in the common marmoset. We designed a novel primer set to detect ZFX and ZFY. A 483-bp band from the ZFX gene and a 471-bp band from the ZFY gene were amplified. Sequencing data of the products amplified from ZFX and ZFY showed the recognition sites of two restriction enzymes, DdeI and MseI, respectively. After digestion of the products using each enzyme, we found that the band patterns between females and males were different. PCR-based sex identification might provide a tool for further breeding studies and experimental embryological studies using marmosets.