Bone loss in C57BL/6J‐OlaHsd mice,a substrain of C57BL/6J carrying mutated alpha‐synuclein and multimerin‐1 genes

The inbred mouse strain C57BL/6 is commonly used for the generation of transgenic mouse and is a well established strain in bone research. Different vendors supply different substrains of C57BL/6J as wild‐type animals when genetic drift did not incur any noticeable phenotype. However, we sporadically observed drastic differences in the bone phenotype of “WT” C57BL/6J mice originating from different labs and speculated that these variations are attributable, at least in part, to the variation between C57BL/6J substrains, which is often overlooked. C57BL/6J‐OlaHsd is a commonly used substrain that despite a well defined deletion in the alpha‐synuclein (Snca) and multimerin‐1 (Mmrn1) genes, was reported to display no obvious phenotype and is used as WT control. Here, we compared the bone phenotype of C57BL/6J‐OlaHsd (6J‐OLA) to C57BL/6J‐RccHsd (6J‐RCC) and to the original C57BL/6J (6J‐JAX). Using μCT analysis, we found that 6J‐OLA mice display a significantly lower trabecular bone mass compared to 6J‐RCC and 6J‐JAX. PCR analysis revealed that both the Snca and Mmrn1 genes are expressed in bone tissue of 6J‐RCC animals but not of 6J‐OLA mutants, suggesting either one or both genes play a role in bone metabolism. In vitro analysis demonstrated increase in osteoclasts number and decreased osteoblast mineralization in cells derived from 6J‐OLA compared with 6J‐RCC. Our data may shed light on unexplained differences in basal bone measurements between different research centers and reiterate the importance of specifying the exact substrain type. In addition, our findings describe the physiological role for Mmrn1 and/or Snca in bone remodeling.     

Genetic differentiation within the inbred C57BL/6J mouse strain

The C57BL/6J (B6) inbred mouse strain is commonly used in biomedical researches. However, some unexpected inconsistency was reported compared with previous studies, and in most cases, it can be attributed to environmental, epigenetic or stochastic differences. The goal of this study was to investigate the genetic stability of the B6 strain maintained in different breeders. B6 mice purchased from five Chinese commercial breeders were examined, and mitochondrial D-loop sequence and 18 microsatellite loci were genotyped. There is no difference in the D-loop sequences, but variations exist in the nucleic microsatellite markers. Combining the data from MGI_4.01, a significant divergence is observed among those mice. The present study indicates that different B6 mice share the common maternal lineage and are still inbred in each breeder, but subline divergence occurs.     

A comparative phenotypic and genomic analysis of C57BL/6J and C57BL/6N mouse strains

Background

The mouse inbred line C57BL/6J is widely used in mouse genetics and its genome has been incorporated into many genetic reference populations. More recently large initiatives such as the International Knockout Mouse Consortium (IKMC) are using the C57BL/6N mouse strain to generate null alleles for all mouse genes. Hence both strains are now widely used in mouse genetics studies. Here we perform a comprehensive genomic and phenotypic analysis of the two strains to identify differences that may influence their underlying genetic mechanisms.

Results

We undertake genome sequence comparisons of C57BL/6J and C57BL/6N to identify SNPs, indels and structural variants, with a focus on identifying all coding variants. We annotate 34 SNPs and 2 indels that distinguish C57BL/6J and C57BL/6N coding sequences, as well as 15 structural variants that overlap a gene. In parallel we assess the comparative phenotypes of the two inbred lines utilizing the EMPReSSslim phenotyping pipeline, a broad based assessment encompassing diverse biological systems. We perform additional secondary phenotyping assessments to explore other phenotype domains and to elaborate phenotype differences identified in the primary assessment. We uncover significant phenotypic differences between the two lines, replicated across multiple centers, in a number of physiological, biochemical and behavioral systems.

Conclusions

Comparison of C57BL/6J and C57BL/6N demonstrates a range of phenotypic differences that have the potential to impact upon penetrance and expressivity of mutational effects in these strains. Moreover, the sequence variants we identify provide a set of candidate genes for the phenotypic differences observed between the two strains.     

Effects of pre-germinated brown rice treatment high-fat diet-induced metabolic syndrome in C57BL/6J mice

To investigate using pre-germinated brown rice (PGBR) to treat metabolic syndrome, we fed one group of mice standard-regular-diet (SRD) for 20 weeks and another group of mice high-fat-diet (HFD) for 16 weeks. We subdivided them into HFD group and HFD + PGBR group whose dietary carbohydrate was replaced with PGBR for 4 weeks. The HFD group gained more weight, had higher blood pressure, heart rate, blood glucose and lipids, liver levels of TG, feces TG and bile acid, lower adipose levels of adipocytokine, lower skeletal muscle IR, IRS-1, IRS-2, PI3 K, Akt/PKB, GLUT-1, GLUT-4, GCK and PPAR-γ; higher liver SREBP-1, SCD-1, FAS, HMGCR, LDLR, CYP7α1 and PPAR-α, and higher adipose SREBP-1, SCD-1, FAS, and lower adipose PPAR-α and adiponectin. The HFD + PGBR group had clearly improved blood pressure, biochemical parameters and above proteins expressions. PGBR successful treatment of metabolic syndrome was achieved through improvements in glucose and lipid synthesis and metabolism.     

三个近交系C57BL/6J小鼠群体微卫星遗传变异分析(英文）

应用微卫星遗传标记对近交系C57BL/6J(B6)小鼠遗传稳定性进行分析。用FAM标记的引物PCR扩增了来自北京和上海三个实验动物生产单位提供的三个B6小鼠群体共15个微卫星位点并进行分型。结果显示,所有位点均处于纯合状态,其中7个位点为多态位点。研究表明各B6群体虽然为高度近交群体,但不同生产单位维持的B6群体之间存在遗传分化。     

The influences of age on T lymphocyte subsets in C57BL/6 mice

The aim of this study is to evaluate the age related changes of T lymphocyte subsets in C57BL/6 mice and immune function. Multi-color immunofluorescence techniques that were used to analyse relative numbers of T lymphocyte subsets include CD4⁺, CD8⁺, naive and memory CD4⁺ and CD8⁺, CD8⁺CD28⁺ T cells in peripheral blood of C57BL/6 mice from different age groups (Group I: 2 months old; Group II: 7 months old; Group III: 21 months old); Splenocytes isolated from different group mice were stimulated with Con A to evaluate the proliferative ability. Compared with group I, group II had a significant reduction in the percentage of CD4⁺, naive CD4⁺ and CD8⁺ T cells and an increase in the percentage of CD8⁺ T cells, while group III had a significant reduction in the percentage of CD4⁺, naive CD4⁺ and CD8⁺ T cells and increase in the percentage of CD8⁺, memory CD4⁺ and CD8⁺ T cells in peripheral blood. Compared with group II, group III had a significant reduction in the percentage of naive CD8⁺ T cells and increase in the percentage of memory CD4⁺ and CD8⁺, CD8⁺CD28⁺ T cells in peripheral blood. The T lymphocyte proliferation in vitro showed that groups II and III had a lower proliferative capacity than group I, between groups II and III, there was not a significant difference. We provide relative values for the T lymphocyte subsets in the different age groups of C57BL/6 mice. The immune system began aging at 7 months old in C57BL/6 mice under a specific pathogen free environment.     

Cardiomyocyte survival and DNA reparation in myocardium of C57Bl/6 and mdx mice after dynamical stress

The cardiomyocytes of mdx mice are the prospective model of research on the survival of terminally differentiated cardiomyocytes and the formation of cardiomyopathy in conditions of oxidative stress. Previously, it was observed that dynamical stress induces the formation of low-molecular fragments of DNA. It is beyond questioning that DNA fragmentation develops through the formation of double-strand breaks in DNA (DNA DSB). To record the appearance and disappearance of DSB DNA in the cardiomyocytes of mdx mice after dynamic stress, the antibodies were applied to the phosphorylated form of an H2Ax histon (γ-H2Ax). In the absence of stress, DSB DNA were detected in the nuclei of cells of the myocardium for C57Bl/6 mice (0.05%) and for mdx mice (6.7%), accordingly. For C57Bl mice, 1 h after stress, the share of marked cardiomyocyte nuclei increased up to 1% and, for mdx mice, up to 41.7%. 24 h after stress, in the myocardium of mdx mice, 5.2% of cardiomyocytes in the nuclei were stained, while, for C57BL/6 mice, marked cardiomyocytes in the nuclei were not determined. 24 h after stress, the cell loss of cardiomyocytes for mdx mice was 2.39–2.50%. For C57Bl mice, the general level of cell loss did not exceed a threshold of 0.38%. The obtained data allow us to suspect that, during the survival of cardiomyocytes in mdx mice, a mechanism of DNA reparation is involved.     

Differential expression and regulation of myristoylated alanine-rich C kinase substrate (MARCKS) in the hippocampus of C57/BL6J and DBA/2J mice

The myristoylated alanine-rich C kinase substrate (MARCKS) is a major protein kinase C (PKC) substrate in brain that binds the inner surface of the plasma membrane, calmodulin, and cross-links filamentous actin, all in a PKC phosphorylation-reversible manner. MARCKS has been implicated in hippocampal-dependent learning and long-term potentiation (LTP). Previous studies have shown DBA/2 mice to exhibit poor spatial/contextual learning, impaired hippocampal LTP, and hippocampal mossy fiber hypoplasia, as well as reduced hippocampal PKC activity and expression relative to C57BL/6 mice. In the present study, we assessed the expression (mRNA and protein) and subcellular distribution (membrane and cytolsol) of MARCKS in the hippocampus and frontal cortex of C57BL/6 and DBA/2 mice using quantitative western blotting. In the hippocampus, total MARCKS mRNA and protein levels in C57BL/6J mice were significantly lower ( approximately 45%) compared with DBA/2J mice, and MARCKS protein was observed predominantly in the cytosolic fraction. MARCKS expression in frontal cortex did not differ significantly between strains. To examine the dynamic regulation of MARCKS subcellular distribution, mice from each strain were subjected to 60 min restraint stress and MARCKS subcellular distribution was determined 24 h later. Restraint stress resulted in a significant reduction in membrane MARCKS expression in C57BL/6J hippocampus but not in the DBA/2J hippocampus despite similar stress-induced increases in serum corticosterone. Restraint stress did not affect cytosolic or total MARCKS levels in either strain. Similarly, restraint stress (30 min) in rats also induced a significant reduction in membrane MARCKS, but not total or cytosolic MARCKS, in the hippocampus but not in frontal cortex. In rats, chronic lithium treatment prior to stress exposure reduced hippocampal MARCKS expression but did not affect the stress-induced reduction in membrane MARCKS. Collectively these data demonstrate higher resting levels of MARCKS in the hippocampus of DBA/2J mice compared to C57BL/6J mice, and that acute stress leads to a long-term reduction in membrane MARCKS expression in C57BL/6J mice and rats but not in DBA/2J mice. These strain differences in hippocampal MARCKS expression and subcellular translocation following stress may contribute to the differences in behaviors requiring hippocampal plasticity observed between these strains.     

具高效种系嵌合能力的C57BL／6J 小鼠ES细胞系的建立

采用小鼠原代成纤维细胞作为饲养层,在含1×103单位白血病抑制因子（LIF）的DMEM高糖培养基中,建成了11个C57BL／6J小鼠的ES细胞系,成系率为9．6％。所建的11个ES细胞系中有5个核型正常率大于70％。这些细胞具早期胚胎细胞的特征,呈碱性磷酸酶阳性,具表达0014基因的特性5进行体内分化实验时能发生广泛的分化。通过嵌合体制作实验证明其中3个系具嵌合能力,并从中筛选出具高效种系嵌合能力的MESPU35细胞系,MESPU35细胞的克隆能达到种系传递,经过基因操作的细胞克隆,也保留了高效的嵌合能力。因此,MESPU35细胞可作为制作突变小鼠的有效载体。     

链脲佐菌素诱导C57BL/6J小鼠2型糖尿病模型研究

目的建立与2型糖尿病(非胰岛素依赖型糠尿病、NIDDM)病人临床特征和发病过程相似的NIDDM动物模型.方法用高脂肪饲料喂养C57BL/6J雄性断乳小鼠3周,腹腔注射链脲佐菌素(STZ),继续喂养4周,测定给药前和给药后1、3、4周非空腹血糖、实验结束时非空腹胰岛素水平,观察胰腺形态学变化.结果喂养3周后(给药前)高脂饲料-STZ组及高脂饲料-柠檬酸组血糖浓度(7.0±0.39)mmol/L、( 6.8±0.45)mmol/L高于普通饲料-STZ组及普通饲料-柠檬酸组(5.3±0.40)mmol/L、(5. 4±0.39)mmol/L,P＜0.05;实验结束时,高脂饲料-STZ组血糖浓度(13 .1±2.01)mmo/L高于高脂饲料-柠檬酸(6.9±0.46)mmol/L、普通饲料-柠檬酸组(6.0± 0.46)mmol/L和普通饲料-STZ组(7.1±0.62)mmol/L(P＜0.05),各组间血浆胰岛素浓度、体重及饮水量差异无显著性,P＞0.05;实验过程中高脂饲料STZ组和柠檬酸组小鼠每天进食热量(64.49±9.2)kJ/只,(70.7±9.6)kJ/只, 显著高于普通饲料STZ组和柠檬酸组(52.7±7.9)kJ/只,(57.3±11.7)kJ/只;各组小鼠胰腺和胰岛细胞形态正常.结论高脂肪饲料和STZ是用C57BL/6J断乳幼鼠建立NIDDM模型所必须的,100mg/kg体重STZ对普通饲料小鼠血糖无影响;用高脂饲料和STZ 处理的小鼠血糖升高、胰岛素浓度正常,与NIDM病人临床特征和发病过程相似;C57BL/6J小鼠易得,建模方法简便,费用低,是在NIDDM实验研究中能广泛使用的较理想的非遗传性NID DM动物模型.     

Expression of hepatic pyruvate carboxylase mRNA in C57BL/6J Ahb/b and congenic Ahd/d mice exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

The activity and level of hepatic pyruvate carboxylase (PC) has been reported to be altered by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) treatment in mice. If alteration in PC level/activity by TCDD influences TCDD toxicity, one would expect to observe an early post-exposure reduction in PC mRNA. To examine the molecular events responsible for the alteration of PC activity in livers of TCDD-treated mice, we designed a synthetic DNA oligonucleotide probe specific for PC mRNA. Northern blot analysis on RNA extracts from hepatic tissue at various times and doses post-TCDD exposure were done. Furthermore, to elucidate the role of the dioxin Ah locus on alterations of PC activity by TCDD, we utilized C57BL/6J (Ah^b/b, Ah high TCDD affinity) mice and a congenic (Ah^d/d, Ah low TCDD affinity) mouse strain. At 8 days post TCDD treatment, a dose-dependent reduction of hepatic PC mRNA levels was observed in Ah^b/b mice. The response, reduction in PC mRNA levels, in the Ah^b/b strain was about 10-fold greater than that of comparably exposed congenic Ah^d/d mice. These results indicate that previously reported reductions in PC activity/level by TCDD treatment of mice is a consequence of a reduction in PC mRNA levels and that the effect requires a competent Ah receptor. © 1996 John Wiley & Sons, Inc.     

从C57BL/6J小鼠胚胎中分离ES细胞系(英文)

ＥＳ细胞（ＥｍｂｒｙｏｎｉｃＳｔｅｍＣｅｌｓ）是来源于小鼠早期胚胎的细胞系,它可以在体外大量培养而不失去其发育的多潜能性。ＥＳ细胞不仅可以用来制作转基因动物,而且能够作为载体进行基因打靶等多种研究。目前,国际上常用的胚胎干细胞系都是来源于１２９小鼠的胚胎。因而,有必要探讨用其它品系小鼠建立ＥＳ系。１９９１年,Ｌｅｄｅｒｍａｎｎ等人首次报道从Ｃ５７ＢＬ／６Ｊ小鼠胚胎中建成了ＥＳ细胞系,但是没有对建立的细胞系进行特性分析。国内柴桂萱等人虽然做了特性分析,但是他们所建细胞系的细胞直径较大,生长速度较慢,不同于常见的ＥＳ细胞系。我们从Ｃ５７ＢＬ／６Ｊ品系小鼠胚胎中共分离了四个ＥＳ细胞系,分别命名为ＣＥ１、ＣＥ２、ＣＥ３、ＣＥ４（Ｆｉｇ．１ａ＆ｂ）。这四个细胞系核型正常率均达到７０％以上。我们检查了ＣＥ２细胞的分化能力,当将ＣＥ２细胞注入同基因型小鼠的皮下后,获得的畸胎瘤（Ｆｉｇ．３）组织切片检查的结果表明：该细胞能够分化成多种组织（Ｆｉｇ．２）。我们也研究了ＥＳ细胞的嵌合能力,用ＩＣＲ小鼠胚胎作为受体胚胎,采用囊胚显微注射法构建嵌合鼠。在幸存的幼鼠中我们获得了来源于ＣＥ２细胞的嵌合鼠（Ｔａｂｌｅ１,Ｆｉｇ．４）。综     

Transglutaminase 3 expression in C57BL／6J mouse embryo epidermis and the correlation with its differentiation

Epidermal-type transglutaminase 3 (TGM3) is involved in the cross-linking of structural proteins to form the cornified envelope in the epidermis. In the present study, we detected the expression of TGM3 in the mouse embryo using RT-PCR.TGM3 mRNA is weakly presented from E11.5 to E14.5 and increases significantly from E15.5 to birth. Then we determined the spatial and temporal expression pattern of TGM3 in the skin and other organs by in situ hybridization. We found a deprivation of TGM3 in skin at E11.5, while a rich supply in periderm cells and a weak expression in basal cells from E12.5 to E14.5. From the period of E15.5 to E16.5, after keratinization in the epidermis, TGM3 was expressed in the granular and cornified layers. The electron microscopic observation of the C57BL/6J mouse limb bud skin development provided several morphological evidences for the epidermal differentiation. The above findings suggest that the expression of TGM3 plays a important role in the epidermis differentiation in embryogenesis.     

Statistical Parameters in Behavioral Tasks and Implications for Sample Size of C57BL/6J:129S6/SvEvTac Mixed Strain Mice

Most mixed strain progeny from gene-knockout experiments typically originate from C57BL/6J and one of the 129 substrains, frequently 129S6/SvEvTac. The results of this behavioral survey suggest that C57BL/6J:129S6/SvEvTac mixed strain mice are amenable to behavioral testing. The variability in behavioral tasks for subjects arising from this mixed strain genetic background does not preclude screening with a battery of behavioral tests. With clues provided by a screen of mixed strain subjects, follow-up analyses with isogenic, congenic, or F1 hybrid animals may be targeted to specific behavioral themes.     

寒冷对雌性C57BL/6小鼠动情周期的影响*

目的:研究寒冷对雌性C57BL/6小鼠动情周期的影响。方法:12只雌性小鼠随机分为对照组、低温组,每组6只;低温组每天4℃暴露4 h,每天阴道涂片法观察小鼠动情状况,对照组饲养于常温动物房;每2 d称量体重,2周后心脏取血、子宫和卵巢,检测小鼠血清E2、FSH、LH、Prl、P水平,进行子宫、卵巢的组织病理学检查。结果:与对照组比较,低温组小鼠体重无显著性差异(P＞0.05),小鼠子宫脏器系数明显较低、动情间期明显延长(P＜0.01),血清FSH显著升高、Prl显著降低(P＜0.01),小鼠子宫腺管扩张,卵巢卵泡数量明显减少。结论:寒冷可使雌性C57BL/6小鼠动情周期延长,进而可能影响生殖功能。     

Hyperalgesic effect of emotional stress in mice of strains C57BL/6J and CBA/CaLac: Interaction with circadian rhythm-related effects

We studied emotional stress-induced modulations of the pain reaction evoked in mice of strains C57BL/6J and CBA/CaLac by subcutaneous injections of formalin; the measurements were performed at midtimes of a “dark” and a “light” phase of the pre-set fixed circadian rhythm. The magnitude of the pain reaction was estimated indirectly, according to characteristics of locomotion of the animal in a running wheel (the velocity of locomotion and the distance covered were considered values inversely correlating with the intensity of the pain response). We found that the intensity of the pain reaction within both phases of the circadian rhythm increased under the influence of stress, and that there were significant differences between the emotional stress-modulated intensities of the pain response observed in the examined genetic strains of mice. Neirofiziologiya/Neurophysiology, Vol. 38, Nos. 5/6, pp. 466–471, September–December, 2006.     

Brain Diurnal Levels of Adenosine 3', 5' Cyclic Monophasphate in C57 Bl/6 and Balb/C Mice

Adenosine 3', 5'-cyclic monophosphate (cAMP) was measured in whole brain of two inbred strains of mice (BALB/C and C57 BL/6) submitted to a lighting schedule consisting of 12 hr light (0700-1900) and 12 hr darkness (1900-0700). Different mean levels of cAMP were found in each strain. Furthermore, statistical analysis of diurnal brain cAMP fluctuations showed different nycthemeral rhythms in both strains. BALB/C was mainly characterized by the presence of very significant 0600 and 0800 harmonics and C57 BL/6 by an orthophase around 1700 hr.

Because both strains were studied under the same experimental conditions of light, temperature and food availability, these factors cannot account for the observed differences, which were thus tentatively interpreted in terms of genetic regulatory processes.