Immune responses of different mouse strains after challenge with equivalent lethal doses of Toxoplasma gondii

Most immunological studies that utilize different strains of inbred mice following T. gondii infection fail to compensate for differences in host susceptibility to the size of the parasite innoculum. To address this concern, susceptible C57BL/6 and resistant CBA/J mice were orally infected with either an equivalent 50% lethal dose (LD50) of brain cysts of the 76K strain of T. gondii (15 cysts in C57BL/6, 400 cysts in CBA/J) or the same dose of parasites in each mouse strain. C57BL/6 mice receiving 400 cysts (LD50 of CBA/J mice) died post infection, whereas CBA/J mice that received 15 cysts (LD50 of C57BL/6 mice) survived. Parasite loads in the brains and serum Toxoplasma-specific IgG1 titers of LD50-infected C57BL/6 mice were significantly higher than those in LD50- or 15 cysts-infected CBA/J mice, whereas splenocyte proliferation to Toxoplasma antigen and the percentage of CD8 alpha+ T cells were reduced in LD50-infected C57BL/6 mice. In contrast, serum IgG2a and IgM titers, the percentage of gamma delta T cells and IFN-gamma expression of spleen of LD50-infected CBA/J mice were higher than those of either 15 cysts-infected CBA/J mice or LD50-infected C57BL/6 mice. These observations demonstrate that the immune response between LD50-infected C57BL/6 and CBA/J mice was more prominent when compared to C57BL/6 or CBA/J mice receiving the same parasite inoculum. These observations would suggest that caution must be excersized in the planning and interpretation of data when the size of the parasite inoculum has not been adjusted for mouse strain.     

不同品系小鼠胚胎玻璃化冷冻保存的比较研究

目的　研究甘油作为冷冻保护剂、不同基因型小鼠对胚胎玻璃化冷冻的影响。方法　采用 6 5mol L的甘油作为冷冻保护剂 ,采用二步法对CBA、NOD、C57BL 6J、ICR及CD1小鼠 3 5d的胚胎进行玻璃化冷冻 ,并比较了不同品系小鼠胚胎的复苏率及移植受孕率。结果和结论　CBA、NOD、C57BL 6J,ICR及CD1的复苏率分别为 5 7 6 %、4 8%、31 3%、86 5 %及 88% ,移植受孕率为 2 1%、2 3 5 %、11%、38%和 35 5 % ,封闭群小鼠的胚胎复苏率、移植受孕率均显著高于近交系小鼠。这提示胚胎的复苏率及移植受孕率可能与小鼠的不同基因型有关。五个品系中 ,桑椹胚及早期囊胚的体外复苏率均显著高于扩张囊胚。这说明不同基因型及胚胎的不同发育阶段对胚胎玻璃化冷冻效果有影响     

Radiation-induced pulmonary endothelial dysfunction and hydroxyproline accumulation in four strains of mice

C57BL mice exposed to 14 Gy of whole-thorax irradiation develop significant histologic lung fibrosis within 52 weeks, whereas CBA and C3H mice do not exhibit substantial fibrosis during this time. The purpose of the present study was to determine whether this strain-dependent difference in radiation histopathology is associated with genetic differences in pulmonary endothelial metabolic activity or in endothelial radioresponsiveness. C57BL/6J, C57BL/10J, CBA/J, and C3H/HeJ mice were sacrificed 12 weeks after exposure to 0 or 14 Gy of 300-kV X rays to the whole thorax. Lung angiotensin converting enzyme (ACE) activity and plasminogen activator (PLA) activity were measured as indices of pulmonary endothelial function; and lung hydroxyproline (HP) content served as an index of pulmonary fibrosis. Lung ACE and PLA activities in sham-irradiated C57BL/6J and CB57BL/10J mice were only half as high as those in sham-irradiated CBA/J and C3H/HeJ mice. Exposure to 14 Gy of X rays produced a slight but nonsignificant reduction in lung ACE and PLA activity in the C57BL strains, and a significant reduction in the CBA/J and C3H/HeJ mice. Even after 14 Gy, however, lung ACE and PLA activities in CBA/J and C3H/HeJ mice were higher than those in sham-irradiated C57BL/6J and C57BL/10J mice. Lung HP content in all four strains increased significantly after irradiation, but this increase was accompanied by an increase in lung wet weight. As a result, HP concentration (per milligram wet weight) remained constant or increased slightly in both C57BL strains and actually decreased in the CBA/J and C3H/HeJ mice. These data demonstrate significant genetic differences in both intrinsic pulmonary endothelial enzyme activity and endothelial radioresponsiveness among the four strains of mice. Specifically, strains prone to radiation-induced pulmonary fibrosis (C57BL/6J, C57BL/10J) exhibit only half as much lung ACE and PLA activity as do strains resistant to fibrosis (CBA and C3H).     

Decline in male mouse pheromone with age

An age-related decline in urinary-borne pheromone was found in male C57BL/6J mice aged from 2 to 30 months. Pheromone activity, estimated by bioassay, declined sharply after about 10 months of age. Two other strains of mice tested (DBA/2J and CBA/HT6J) also appeared to show an age-related decline in pheromone activity. Within each strain, however, pheromone activity was consistently similar to or higher than that of the C57BL/6J male mice. The DBA/2J and BALB/cWt strains appeared to be high pheromone producers, and the C57BL/6J and CBA/HT6J strains, low producers. This report is the first demonstration of a decline with age in male mouse pheromone activity. This decline appears to be synchronized with the well-defined loss of reproductive function in female mice.     

Strain variation in the susceptibility and immune response to Clonorchis sinensis infection in mice

Mice have shown various susceptibility to infection by Clonorchis sinensis. To compare the intra-specific variation in the host-parasite relationship of C. sinensis, 6 strains of mice (ICR, BALB/c, C57BL/6, DDY, CBA/N, and C3H/HeN) with 3 different haplotypes were evaluated on their susceptibility. The worm recovery rate and immunological responses were observed after 4 and 8 weeks of infection with 30 metacercariae. The highest worm recovery rate was observed as 20.7% in the C3H/HeN strain after 4 weeks of infection along with histopathological changes. The rate was 10.0% in C57BL/6 mice after 8 weeks. ICR, BALB/c, and CBA/N showed elevated levels of IgE at both time points when compared to the rest of the strains. The serum IgG1 and IgG2a levels were elevated in most of the strains; however, the C57BL/6 strain showed a lower level of IgG2a that indicated the IgG1 predominance over IgG2a. The production of IL-4 after concanavalin-A stimulation of splenocytes slightly increased among the mouse strains except C3H/HeN after 4 or 8 weeks of infection, but each strain produced high levels of IFN-γ after 8 weeks, which implied mixed Th1/Th2 responses. ICR, DDY, CBA/N, and C3H/HeN strains showed a significantly increased level of IL-10 after 8 weeks as compared to C57BL/6. All of the strains showed an increased level of IL-13 and suggested fibrotic changes in the mice. In conclusion, mice are insusceptible to infection with C. sinensis; however, the C57BL/6, BALB/c and ICR strains are relatively susceptible after 8 weeks of infection among the six strains. Worm expulsion may be one of the causes of low susceptibility of C3H/HeN mice strain at the 8th week. Elevated IgE, IFN-γ, and IL-13 of infected mice suggest both Th1 and Th2 responses that may be related to the low host susceptibility.     

不同品系小鼠对代谢性高尿酸血症造模的影响

目的：分别以昆明种小鼠及ICR、C57BL/6J小鼠为研究对象,比较在复制高尿酸血症模型时可能的小鼠品系差异,并通过降尿酸药物别嘌呤醇与非布索坦验证选择降尿酸药物筛选时选用不同品系动物造模的影响。方法：采用不同剂量次黄嘌呤腹腔注射联用尿酸酶抑制剂氧嗪酸钾皮下注射给药,测定不同造模时段各品系小鼠血清尿酸值。结果：ICR、C57BL/6J小鼠对高尿酸血症造模耐受显著高于昆明种小鼠,在腹腔注射次黄嘌呤500mg/kg,皮下注射氧嗪酸钾300mg/kg时,才可获得稳定的可用于药物筛选的高尿酸血症模型。结论：选择高尿酸血症在体模型时,昆明种小鼠灵敏度高于ICR小鼠以及近交系的C57BL/6J小鼠。     

Effect of genotype on the development of aggressive and submissive behavior in the mouse

Aggressive and submissive behaviour was studied in CBA/Lac and C57BL/6J strains of mice during long-term intermale interaction with syngenic partners. It was shown that the aggressiveness of aggressive C57BL/6J animals was more expressive than that of CBA/Lac' ones. The structure of submissive behaviour of this strains' encounters was also significantly different. Prolonged-defeat experience changed the character of submissive behaviour of C57BL/6J, but not of CBA/Lac' ones. Aggression of dominant animals considerably decreased in both strains. It is suggested that CBA/Lac and C57BL/6J mice had different mechanisms of suppression of intermale aggression.     

Effect of different factors on the sex ratio in laboratory mouse embryogenesis

Influence of two factors on distribution of embryos according to the sex is considered: genetic peculiarities of inbred mice and hybrid mice, as well as spontaneous embryonal death of the embryos of different sex. The work has been performed on C3H, CBA, C57BL strains of mice and on hybrid mice of CBA/C57BL and ICR/In(X)1H strains. The sex ratio in the mice studied is balanced. In the CBA/C57BL hybrid mice a certain shift in the sex ratio is noted towards female embryos. In the offspring of the ICR/In(X)1H hybrid mice the sex distribution of the embryos does not differ from the ratio 1:1. The results of the investigation confirm the opinion of the literature that genetic peculiarities of the inbred mice do not essentially influence the sex ratio in their offspring, while fluctuation in the sex ratio in the hybrid mice are evidently connected, in a greater degree, with their genetic peculiarities. As demonstrates the analysis of the sex relation and the embryonal death, there is no selective death in the embryos of any sex during embryogenesis in the mice investigated.     

Exploratory activity of mice of different genetic strains after olfaction disruption by 3-methylindole (skatole)

The behavior of mice of two inbred strains (C57BL/6J and CBA) and their F1 hybrids was evaluated in the open field test after intraperitoneal administration of 3-methylindole (skatole) disrupting epithelium of the main olfactory system. High motor and exploratory activities and emotional sensitivity was observed in intact C57BL/6J mice compared to CBA mice and their hybrids. Anosmia induced by intraperitoneal administration of skatole changed the behavior of C57BL/6J and CBA mice. The direction of the observed changes in the orientation and exploratory behavior of anosmic animals was different. Anosmia decreased motor and exploratory activities in C57BL/6J mice and increase them in CBA mice. Intact hybrid mice demonstrated the predominance of the CBA genotype in the orientation and exploratory activity in the test used. Anosmia in hybrid animals had no significant effect on the orientation and exploratory behavior.     

Schistosoma japonicum: Infection characteristics in mice of various strains and a difference in the response to eggs

Female mice of 12 inbred strains were exposed to 20–25 cercariae of Schistosoma japonicum and infection status determined at day 40 by counting numbers of adult worms, eggs in faeces and eggs in a segment of liver. Most mouse strains appeared to be ‘permissive’ hosts although at least one strain (129/J) was shown to be relatively resistant in terms of day 40 adult worm numbers. In a radioisotopic lung assay for sensitivity to eggs, and developed as a rapid means of assessing granuloma formation, CBA/H mice were shown to differ from C57BL/6 mice in being non-responders. Histological examination of lungs of sensitized CBA/H and C57BL/6 mice injected intravenously with eggs established that granuloma formation was much more intense in C57BL/6 than CBA/H mice. Preliminary indications are that infected CBA/H mice are also low anti egg circumoval precipitin (COP) responders. Analysis of immune responses to isolated egg antigens in these two strains, and identification of the antigens of eggs to which such responses are directed in C57BL/6 mice, should provide insights into immunological disease processes (such as granulomatous inflammation) in this model system of japonicum schistosomiasis.     

Differences in spermatogenesis in cryptorchid testes among various strains of mice

The purpose of the study reported here was to define strain differences in spermatogenesis in cryptorchid testes in mice. Mice of strains A/J, BALB/c, CBA/N, C3H/He, C57BL/6 (B6), ddY and ICR were found to be sensitive to heat stress attributable to experimentally induced cryptorchidism. In contrast, mice of strains AKR/N (AKR), MRL/MpJ-+/+ (M+) and MRL/MpJ-lpr/lpr (lpr) were resistant to heat stress. Relative increases of apoptotic cells were detected in the sensitive group, but not in the resistant group. A decrease of proliferating cell nuclear antigen-immunoreactive cells after experimentally induced cryptorchidism was observed only in the sensitive group. These results suggested that heat stress-resistant germ cells were present in MRL and AKR strains, possibly originating from the genetic background.     

Experience of defeat increases the susceptibility to catatonic - like state in mice

The ability to develop the catatonic-like state (reflex immobility reaction - RIR) due to stimulation of the skin at the scruff was investigated in mice of two strains — C57BL/6J and CBA/Lac. The total time of immobility and number of paroxysms during test were measured. It has been shown that the number of paroxysms was significantly fewer and the total time of immobility was significantly longer in CBA/Lac strain than in C57BL/6J. In each strain group housed animals as well as submissive ones with successive experience of defeats demonstrated a more expressed immobility than individually housed or aggressive males with successive experience of victories, respectively. Changing the social status in aggressive animals as a consequence of confrontation with aggressive males resulted in the increased immobility in CBA/Lac but not in C57BL/6J mice. The results suggest that the experience of defeat in submissive males is connected with increased ability to develop RIR.     

Effect of a single severe stress on behaviour of males and females in the mouse inbred strains CBA/Lac and C57BL/6J

The effect of single severe stress in the form of forced swimming on the behavior of males and females in the mouse inbred strains CBA/Lac and C57BL/6J were examined in the open field test. Measurements were carried out within two hours after the stress exposure (Trial 1) and repeated 2 hours thereafter (Trial 2). Intact males and females of the both mouse strains which tested in the open field twice too were used as control. An increased latency was found until first escape from the center both in males and females of the CBA/Lac strain within two hours after the end of forced swimming. This parameter was still high in females in the Trial2. Four out of seven behavior parameters were changed in females of the C57BL/6J strain two hours after the stress exposure, but their behavior was similar to control in the Trial 2. The males of the C57BL/6J strain demonstrated the least changed behavior in the open field test after the stress exposure with the exception of increased number of grooming in the Trial 1. Further on, a detailed analysis of repeated testing in the open field within intact and stressed mice of both strains was performed. This comparison allowed revealing hereditary and gender peculiarities in the mouse behavior after single severe stress exposure. The results are discussed in respect to the possible genetically inherent increased traitanxiety in females of C57BL/6J strain and the state of anxiety in females of CBA/Lac strain.     

Augmentation of mouse natural killer cell activity by muramyl dipeptide and its analogs

The ability of muramyl dipeptide (MDP) and its structural analogs (des-MDP, abu-MDP, and des-abu-MDP) to influence mouse natural killer (NK) cells in two different strains of mice was examined. In CBA/J mice, administration of MDP by both intraperitoneal (ip) and intravenous (iv) routes enhanced splenic NK cell activity. Maximum augmentation of NK cell activity was observed 3 days after MDP treatment. NK cell activity was also stimulated upon in vitro culture of CBA/J mouse spleen cells with MDP. Only iv inoculation of MDP to C57BL/6 mice 7 days previously enhanced NK cell activity of spleen cells. Peritoneal NK cell activity was not affected in either strain of mice, regardless of the route of inoculation of MDP. Two structural analogs of MDP, abu-MDP and des-abu-MDP, enhanced peritoneal NK cell activity, whereas des-MDP had no effect when tested 3 days after ip treatment of CBA/J mice with these compounds. Peritoneal NK cell activity of C57BL/6 mice was not modulated by des-MDP, abu-MDP, or des-abu-MDP. A synergistic effect on peritoneal NK cell activity was observed in both CBA/J and C57BL/6 mice treated first with MDP and then with lipopolysaccharide (LPS) or Bacillus Calmette-Guerin (BCG).     

Susceptibility to sarcomere injury induced by single stretches of maximally activated muscles of mdx mice.

The purpose was to investigate the contribution of mechanical damage to sarcomeres to the greater susceptibility of dystrophic muscle fibers to contraction-induced injury. Single stretches provide an effective method for studying mechanical factors that contribute to the initiation of contraction-induced injury. We hypothesized that, after single stretches, the deficits in isometric force would be greater for muscles of mdx than C57BL/10 mice, whereas membrane damage would be minimal for all muscles. Extensor digitorum longus (EDL) and soleus muscles of mice were removed under anesthesia with Avertin (tribromoethanol). During the plateau of a maximum isometric contraction in vitro, muscles were stretched through single strains of 20-60% fiber length. Isometric force was remeasured 1 min later, and muscles were then incubated in procion orange dye to identify fibers with membrane damage. Force deficits at 1 min were two- to threefold greater for EDL muscles of mdx compared with C57BL/10 mice, whereas no significant differences were observed between soleus muscles of mdx and C57BL/10 mice. For all muscles, membrane damage was minimal and not significantly increased by single stretches for either strain of mice. These data support a critical role of dystrophin maintaining sarcomere stability in EDL muscles, whereas soleus muscles retain abilities, in the absence of dystrophin, not different from control muscles to resist sarcomere damage.     

Muscle damage and repair in voluntarily running mice: strain and muscle differences

Summary Soleus, extensor digitorum longus and tibialis anterior muscles of mice voluntarily running in wheels for periods of 5 to 120 days were studied in spaced serial and serial cross-sections. Shortly after the onset of running and during the next 2 weeks, degeneration, necrosis, phagocytosis and regeneration of muscle fibers, satellite cell proliferation and cellular infiltration were found in soleus muscles of mice from all strains investigated (CBA/J, NMRI, C57b, NIH, SWS and Balb/c). Tibialis anterior but not extensor digitorum longus muscles were also damaged. Predominantly high-oxidative fibers were affected (both slow-oxidative and fast oxidative glycolytic in soleus, fast-oxidative glycolytic in tibialis anterior). Denervated soleus muscles that had been passively stretched during running were not damaged. Evidence was found that, during the early period of running, split fibers form by myogenesis within (regeneration) or outside (satellite cell proliferation) necrotic muscle fiber segments. Split fibers persisted in solei of long-term (2 to 3 months) exercised CBA/J but not NMRI mice. In 6 out of 20 solei of CBA/J runners exercised for 2 months or longer, fiber-type grouping was observed in the areas where extensive damage usually occurred in the early periods. The results show that different muscles are damaged and repaired to varying degrees and that marked interstrain and inter-individual differences are present. It appears that acute muscle injury occurring upon onset of voluntary running is a usual event in the adaptation of muscles to altered use.     

Properties of slow- and fast-twitch skeletal muscle from mice with an inherited capacity for hypoxic exercise

Muscle fiber type, myosin heavy chain (MHC) isoform composition, capillary density (CD) and citrate synthase (CS) activity were investigated in predominantly slow-twitch (soleus or SOL) and fast-twitch (extensor digitorum longus or EDL) skeletal muscle from mice with inherited differences in hypoxic exercise tolerance. Striking differences in hypoxic exercise tolerance previously have been found in two inbred strains of mice, Balb/cByJ (C) and C57BL/6J (B6), and their F1 hybrid following exposure to hypobaric hypoxia. Mice from the three strains were exposed for 8 weeks to either normobaric normoxia or hypobaric hypoxia (1/2 atm). Hypoxia exposure led to a slightly higher 2b fiber composition and a lower fiber area of types 1 and 2a in SOL of all mice. In the EDL, muscle fiber and MHC isoform composition remained unaffected by chronic hypoxia. Chronic hypoxia did not significantly affect CD in either muscle from any of the three strains. There were relatively larger differences in CS activity among strains and treatment, and in SOL the highest CS activity was found in the F1 mice that had been acclimated to hypoxia. In general, however, neither differences among strains nor treatment in these properties of muscle vary in a way that clearly relates to inherited hypoxic exercise tolerance.     

Genetic differences in BCG-induced resistance to Schistosoma mansoni are not controlled by genes within the major histocompatibility complex of the mouse.

Induction of nonspecific resistance to Schistosoma mansoni infection after the i.v. injection of viable BCG was investigated in outbred mice and a panel of inbred and H-2 congenic strains. Significant protection was induced in CF1, A/J, C57BL/6, C57BL/10, DBA/2, C57BR, and SJL mice. BALB/c mice were not protected whereas CBA and C3H mice expressed intermediate degrees of protection. Expression of the protective phenomenon is not controlled by genes within the MHC as shown by the marked differences in response between BALB/c and DBA/2 (H-2d) as well as between C57BR and C3H (H-2k) mice. H-2 congenic strains with C57BL/10 background (B10.A and B10.D2) were high responders. BALB.B10 mice carrying the high responder (B10) MHC on the nonresponder (BALB/c) background were not protected. The degree of splenic hypertrophy did not correlate with the expression of nonspecific resistance. These results demonstrate that, in addition to controlling specific immune responses, genetic differences influence the nonspecific protective phenomena related to BCG administration as well.     

Skeletal muscle adaptations to microgravity exposure in the mouse.

To investigate the effects of microgravity on murine skeletal muscle fiber size, muscle contractile protein, and enzymatic activity, female C57BL/6J mice, aged 64 days, were divided into animal enclosure module (AEM) ground control and spaceflight (SF) treatment groups. SF animals were flown on the space shuttle Endeavour (STS-108/UF-1) and subjected to approximately 11 days and 19 h of microgravity. Immunohistochemical analysis of muscle fiber cross-sectional area revealed that, in each of the muscles analyzed, mean muscle fiber cross-sectional area was significantly reduced (P < 0.0001) for all fiber types for SF vs. AEM control. In the soleus, immunohistochemical analysis of myosin heavy chain (MHC) isoform expression revealed a significant increase in the percentage of muscle fibers expressing MHC IIx and MHC IIb (P < 0.05). For the gastrocnemius and plantaris, no significant changes in MHC isoform expression were observed. For the muscles analyzed, no alterations in MHC I or MHC IIa protein expression were observed. Enzymatic analysis of the gastrocnemius revealed a significant decrease in citrate synthase activity in SF vs. AEM control.     

Effect of murine strain on metabolic pathways of glucose production after brief or prolonged fasting

Background strain is known to influence the way a genetic manipulation affects mouse phenotypes. Despite data that demonstrate variations in the primary phenotype of basic inbred strains of mice, there is limited data available about specific metabolic fluxes in vivo that may be responsible for the differences in strain phenotypes. In this study, a simple stable isotope tracer/NMR spectroscopic protocol has been used to compare metabolic fluxes in ICR, FVB/N (FVB), C57BL/6J (B6), and 129S1/SvImJ (129) mouse strains. After a short-term fast in these mice, there were no detectable differences in the pathway fluxes that contribute to glucose synthesis. However, after a 24-h fast, B6 mice retain some residual glycogenolysis compared with other strains. FVB mice also had a 30% higher in vivo phosphoenolpyruvate carboxykinase flux and total glucose production from the level of the TCA cycle compared with B6 and 129 strains, while total body glucose production in the 129 strain was approximately 30% lower than in either FVB or B6 mice. These data indicate that there are inherent differences in several pathways involving glucose metabolism of inbred strains of mice that may contribute to a phenotype after genetic manipulation in these animals. The techniques used here are amenable to use as a secondary or tertiary tool for studying mouse models with disruptions of intermediary metabolism.