Search

The mouse is the most commonly used model species in biomedical research. Just as human physical and mental health are influenced by the commensal gut bacteria, mouse models of disease are influenced by the fecal microbiome (FM). The source of mice represents one of the strongest influences on the FM and can influence the phenotype of disease models. The FM influences behavior in mice leading to the hypothesis that mice of the same genetic background from different vendors, will have different behavioral phenotypes. To test this hypothesis, colonies of CD-1 mice, rederived via embryo transfer into surrogate dams from four different suppliers, were subjected to phenotyping assays assessing behavior and physiological parameters. Significant differences in behavior, growth rate, metabolism, and hematological parameters were observed. Collectively, these findings show the profound influence of supplier-origin FMs on host behavior and physiology in healthy, genetically similar, wild-type mice maintained in identical environments.

To avoid microbial contamination risk, vinyl film isolators are generally used in animal microbiome experiments involving germ-free (GF) mice and/or gnotobiotic (GB) mice. However, it can take several months to gain expertise in operating the isolator competently. Furthermore, sterilization and sterility testing, which are essential for isolator preparation, can take more than 20 days. Hence, we built an experimental rearing environment that combines an individual ventilation cage system and a bioBUBBLE clean room enclosure to easily set up an experimental animal microbiome environment for animal facilities. In this work, a three-step evaluation was conducted. First, we examined whether GF mice can be maintained in this rearing environment without bacterial contamination. Next, we examined whether GF and GB mice can be maintained without cross-contamination in one individual ventilation cage rack. Finally, we tested whether GF mice can be maintained in a biological safety cabinet controlled by negative pressure. In our series of experiments, no microbial contamination occurred over more than 3 months. These results indicated that our rearing system that combines the individual ventilation cage and bioBUBBLE systems can be used not only for experiments with GF mice but also for Biosafety Level 2 experiments that handle bacteria. Our system can mitigate various disadvantages of using vinyl film isolators. In conclusion, we established an experimental method with improved working time and efficiency compared with those of the previous vinyl isolator method.

In mice, ovarian stimulation via hormone administration is an effective method for obtaining many ova simultaneously, but its effect is reduced by the influence of aging. In this study, we demonstrate that this problem can be improved by administering the gonadotropin-releasing hormone antagonist Cetrorelix prior to ovarian stimulation. Before 12-month-old female mice were injected with 5 IU pregnant mare serum gonadotropin and 5 IU human chorionic gonadotropin, we administered 5 µg/kg Cetrorelix for 7 consecutive days (7 times) or 3 times once every 3 days. As a result, 8.7 ± 1.9 (mean ± SEM, n=10) and 9.8 ± 1.3 (n=10) oocytes were obtained, respectively, as opposed to 4.7 ± 1.2 oocytes (n=9) in the case of no administration. Collagen staining of ovarian tissue showed that Cetrorelix administration reduced the degree of fibrosis, which improved ovarian function. In addition, equivalent fertilization and fetal development rates between control and Cetrorelix-treated aged mouse-derived oocytes were confirmed by in vitro fertilization and embryo transfer (Fertilization rate; control: 92.2% vs. 3 times: 96.9%/7 times: 88.5%, Birth rate; control: 56.4% vs. 3 times: 58.3%/7 times: 51.8%), indicating the normality of the obtained oocytes. It is concluded that Cetrorelix improved the effect of superovulation in aged mice without reducing oocyte quality. This procedure will contribute to animal welfare by extending the effective utilization of aged female breeding mice.

Enterovirus A71 (EV-A71) is the major pathogen of hand, foot, and mouth disease (HFMD); in some severe cases, it could develop into central nervous system (CNS) disease such as aseptic meningitis, encephalitis, and neurogenic pulmonary edema in children under 5 years. The EV-A71 pathogenesis which is involved with the CNS is unclear due to the lack of a simple and reliable mouse model thus far. Most clinical EV-A71 isolates could not effectively infect the neonatal mouse, which used to be an EV-A71 infection model. The small extracellular vesicles (sEVs) released from clinical EV-A71 isolate-infected cells were infectious in cell lines and could cause a high viral replication in mice. Neonatal ICR mice were injected intraperitoneally with these infectious sEVs and showed more weight loss and higher mortality than those mice injected with the clinical EV-A71 isolate. By using these sEVs, we provided a simple and effective method by which we can generate a stable and valuable animal model for the studies of EV-A71 pathogenesis and therapy. IMPORTANCE EV-A71 was supposed to infect the CNS through the neural pathway and the circulation of the blood in previous studies. Reverse axon transport had been confirmed as an important pathway for EV-A71 to infect the CNS; however, it is still unknown how EV-A71 infects the CNS through the circulation of the blood. Combined with the infectivity of sEVs secreted from EV-A71-infected cells and the characteristic that sEVs could cross the blood-brain barrier, we considered that sEVs may play a vital role in EV-A71 pathogenesis of the CNS., (Copyright © 2020 Gu et al.)

Soy products contain abundant genistein and daidzein isoflavones. Orally ingested soy isoflavones are partially metabolized to isoflavan by enteric bacteria. Their levels in the blood increase after soy products are eaten. In this study, we investigated the influence of genistein, daidzein, and equol by intraperitoneal administration in lactating mice. Genistein decreased the secretion of α- and β-casein and downregulated the gene expression of Csn1 , Csn2 , Csn3 , and Wap while inactivating the signal transducer and activator of transcription 5 (STAT5) and ERK1/2. In contrast, equol increased Csn1 - 3 expression while inactivating STAT3. Daidzein did not show inhibitory effects on milk production. The effects of genistein and equol were also confirmed in lactating mammary epithelial cells (MECs), which were cultured in the presence of soy isoflavones and equol at physiological concentrations for 7 days. These findings indicate that genistein, daidzein, and equol influence milk production in MECs in vivo and in vitro in distinctly different ways.

The CRISPR/Cas9 system is widely used to generate gene-edited animals. Here, we developed an efficient system for generating genetically modified mice using maternal Cas9 from Cas9 transgenic mice. Using this system, we achieved lower mosaicism and higher rates of knock-in success, gene-editing, and birth compared to the similar parameters obtained using exogenously administered Cas9 (mRNA/protein) system. Furthermore, we successfully induced simultaneous mutations at multiple loci (a maximum of nine). Our novel gene-editing system based on maternal Cas9 could potentially facilitate the generation of mice with single and multiple gene modifications.

Lipoprotein lipase (LPL) and hepatic triglyceride lipase (HTGL) have an important role in lifestyle-related diseases. To evaluate species differences, we compared LPL and HTGL activities in different animal models of lifestyle-related diseases using the same assay kit. Normal animals (JW rabbits, ICR mice, and SD rats), a hypercholesterolemic animal model (WHHLMI rabbits), and obese animal models (KK-A y mice and Zucker fatty rats) fed standard chow were used in this study. Plasma was prepared before and after an intravenous injection of heparin sodium under fasting and feeding. LPL and HTGL activities were measured with the LPL/HTGL activity assay kit (Immuno-Biological Laboratories) using an auto-analyzer. Only in mice, high HTGL activity was observed in pre-heparin plasma. In normal animals, LPL and HTGL activities were high in ICR mice and SD rats but low in JW rabbits. Compared to normal animals, LPL activity was high in Zucker fatty rats and WHHLMI rabbits at both fasting and feeding, while LPL activity after feeding was low in KK-A y mice. HTGL activity was higher in fasted and fed WHHLMI rabbits and fasted Zucker fatty rats, but was lower in fed KK-A y mice. Gender difference was observed in HTGL activity in SD rats and LPL activity in WHHLMI rabbits but not in ICR mice. In conclusion, this simple assay method was effective for measuring LPL and HTGL activities of experimental animals, and the activities are highly regulated depending on animal species, animal models, feeding/fasting conditions and genders.

Exposure to chiral pesticides poses many potential health risks. In this study, we examined the impacts of exposure to penconazole and its enantiomers on gut microbiota and metabolic profiles in mice. The relative abundance of microbiota in cecal content significantly changed following exposure to penconazole and its enantiomers. At the genus level, the relative abundances of seven gut microflora were altered following exposure to (-)-penconazole. Both (±)-penconazole and (+)-penconazole caused significant changes in the relative abundances of five gut microflora. In addition, targeted serum metabolomics analysis showed disturbed metabolic profiles following exposure. Respectively, (±)-penconazole, (+)-penconazole, and (-)-penconazole exposure significantly altered the relative levels of 29, 23, and 36 metabolites. In general, exposure to penconazole and its enantiomers caused disorders in gut microbiota and metabolic profiles of mice. The potential health risks of penconazole and its enantiomers now require further evaluation.

The aim of this study was to investigate the role of pyroptosis in the cryopreservation and transplantation of mouse ovarian tissues; the effects of pyroptosis inhibitior on the ovarian graft function were also explored. ICR (institute of cancer research) mice were randomly divided into control group and experimental groups (n = 10 per group). The experimental groups included fresh graft group (autograft), cryopreserved graft group (cryopreservation + autograft), and pyroptosis inhibition group (cryopreservation + autograft + pyroptosis inhibitor). At the third day after auto-transplantation, caspase-1 and NLRP3 protein expression in grafts were assessed by Western blot; in the meantime, serum concentration of IL-1β was examined by ELISA. After 28 days of auto-transplantation, estradiol concentrations and follicular densities of grafts were evaluated. The caspase-1 and NLRP3 protein expression in grafts from all the experimental groups were significantly higher than that from control group respectively; moreover, there was a significant increase in serum concentrations of IL-1β in all experimental groups compared with control group. The concentration of estradiol and follicular densities of grafts in pyroptosis inhibition group were significantly higher than that in cryopreserved graft group. Pyroptosis is involved in cryopreservation and auto-transplantation of mouse ovarian tissues, and pyroptosis inhibition can improve the ovarian graft function., (Copyright © 2019. Published by Elsevier Ltd.)

Graphene quantum dots (GQDs) have attracted considerable attention across multiple fields, particularly biomedical research. However, the effects of GQDs on reproductive and offspring health in mammals are unclear. Here, we show that GQD exposure via oral gavage or intravenous injection had no effect on the frequency and timing of sexual behaviors in male mice. GQD-exposed male mice retained healthy structural and functional reproductive physiology (e.g., production and storage of healthy sperm, maintenance of normal total protein and key enzyme concentrations in testes) of the testes and epididymides, as well as normal testosterone levels. Female mice housed with GQD-exposed males produced first, second, and subsequent litters of healthy pups without obvious differences to females housed with buffer-treated males. These findings may be explained by the low toxicity of GQDs in germ cells and their rapid excretion after exposure in mice, mainly via the urine and/or feces; GQDs, even at high doses, are virtually undetectable in male mouse testis, epididymis, and brain. Our findings reveal the short- and long-term effects of GQD exposure on male mouse sexual behaviors, reproductive activity, and offspring development and indicate the potential mechanisms of action of GQDs to provide further insight into their bio-safety., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: The challenges to embody the complexity of symptoms and biological mechanism of affective disorders question the value of animal models as well as their reproducibility and validity. Validity is further hindered by large individual variability in many models. Whereas individual variability presents a challenge, it can also be used to study susceptibility and resistance. One of the frequently used models for screening antidepressants and interventions related to depression is the forced swim test (FST). The FST is typically performed only once., Methods: The current study was designed with a number of objectives: (1) Examine the group effects of repeated FST (2) Examine the interaction between sex and repeated FST and (3) examine the consistency of individual variability across test and retest in the FST. We exposed ICR female and male mice to the FST 3 or 5 times with two days between exposures. Immobility time was analyzed across exposures at the group and the individual levels using repeated measures ANOVA as well as Pearson's correlations., Results: As expected, repeated exposure to the FST resulted in increased immobility across exposures with no consistent effect of sex. At the level of individual mice, immobility time showed correlation across exposures., Discussion: The current study demonstrates the effects of repeating the FST in both sexes with attention to individual variability. The results suggest that the FST can be used more than once and that mice show a consistent individual pattern of responding in the test., (Copyright © 2018 Elsevier Inc. All rights reserved.)

With the development of the ultra high voltage transmission technology, the voltage level of transmission line rised. Accordingly, the strength of electric field in the vicinity of transmission line increased, thus possible health effects from electric field have caused many public attentions. In this study, in order to compare effects induced by static electric field (SEF) and power frequency electric field (PFEF) on immune function, Institute of Cancer Research (ICR) mice were exposed to 35 kV/m SEF (0 Hz) and PFEF (50 Hz),respectively. Several indicators of white blood cell, red blood cell as well as hemoglobin in peripheral blood were tested after exposure of 7, 14 and 21 days, respectively. There was no significant difference in any indicators under SEF exposure of 35 kV/m for 7d, 14d and 21d between experimental group and control group. Under the PFEF exposure of 35 kV/m, white blood cell count significantly reduced after exposure of 7d, 14d and 21d. Meanwhile, red blood cell count significantly reduced after exposure of 7d, and returned to normal level through the compensatory response of organism after exposure of 14d and 21d. Hemoglobin concentration significantly decreased only after exposure of 21d. Based on tested results of hematological indicators, SEF exposure of 35 kV/m did not affect immune functions in mice but PFEF exposure of 35 kV/m could cause a decline of immune function. This difference of effects from SEF and PFEF on immune function was possibly caused by the difference of the degree of molecular polarization and ion migration in organism under exposure of two kinds of electric fields., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Daily torpor is a physiological adaptation in small mammals and birds, characterised by drastic reductions in metabolism and body temperature. Energy-constraining conditions, such as cold and starvation, are known to cause the expression of daily torpor. However, the reason for high degrees of inter- and intra-individual variation in torpor expression (TE) in similar situations is not clear. As littermates of altricial animals are exposed to an uneven allocation of maternal resources from conception to weaning, we tested whether early nutritional experiences have long-term effects on TE in adults. We used full-sibling littermates of laboratory mice that as adults were starved overnight to induce torpor. We measured body mass from birth until adulthood as an indicator of nutritional status, and calculated the relative body mass (RBM) as an indicator of the difference in nutritional status within a litter. After maturation, we subjected mice to five repeated torpor induction trials involving 24 h of fasting and 5 days of recovery. Half of the female mice displayed great individual variation in TE whereas male mice rarely exhibited daily torpor. In females, RBM at birth influenced TE, irrespective of body mass in adulthood; thus, female mice born with low RBMs displayed high TE in adulthood. In conclusion, we provide evidence that TE in mice differs among littermates, and that this variation is linked closely to heterogeneous nutritional experiences during the fetal period., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2018. Published by The Company of Biologists Ltd.)

Introduction: Pica behavior, kaolin ingestion, in rats and mice can be used as an assessment of nausea and vomiting; however, we observed that the incidence of pica behavior in ICR strain mice varied markedly. We investigated the susceptibility of four strains of mice (ICR, BALB/c, C57BL/6, and DBA/2) to the development of pica behavior., Methods: Mice received cisplatin (7.5 mg/kg, i.p.) with or without a serotonin 5-HT 3 receptor antagonist (granisetron: 0.1 mg/kg, i.p.) or tachykinin NK 1 receptor antagonist (fosaprepitant: 30 mg/kg, i.p.), and then their daily kaolin intake was measured for 2 days. We examined the expression of preprotachykinin (PPT)-A mRNA in the medulla of cisplatin-treated mice 8 and 32 h after drug administration., Results: All mice except for ICR strain significantly increased kaolin intake after cisplatin administration. Among the tested strains, DBA/2 mice compared to BALB/c and C57BL/6 mice notably showed pica behavior on both days (P < 0.0001). The expression of PPT-A mRNA was significantly increased 8 h after cisplatin administration in all strains, but the increase remained on the second day only in DBA/2 mice (P < 0.05). Granisetron significantly inhibited pica behavior in DBA/2 mice on the first day (P < 0.0001), but not the second day; however, fosaprepitant completely inhibited the pica behavior on both days (P < 0.001)., Discussion: These results indicate that cisplatin-induced pica behavior in mice is likely to be influenced by the genotype, and that DBA/2 mice are useful to analyze the emetogenic or anti-emetic potential of drugs in preclinical studies., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Understanding of physiological responses of organisms is typically based on data collected during an isolated event. Although many fundamental insights have been gained from these studies, evaluating the response to a single event ignores the fact that each individual has experienced a unique set of events throughout its life that may have altered its physiology. The idea that prior experiences can influence subsequent performance is known as a carry-over effect. Carry-over effects may explain much of the variation in performance found among individuals. For example, high physical activity has been shown to improve mitochondrial respiratory function and biogenesis and reduce oxidative stress, and has been linked to improved health and longevity. In this study, we asked whether the bioenergetic differences between active and inactive individuals carry over to impact performance in a subsequent reproductive event and alter a female's reproductive outcome. Female mice that had access to a running wheel for a month before mating gave birth to a larger litter and weaned a heavier litter, indicating that high physical activity had a positive carry-over effect to reproduction. Mice that ran also displayed higher mitochondrial respiration and biogenesis with no changes in endogenous antioxidant enzymes. These results provide a mechanistic framework for how the conditions that animals experience before breeding can impact reproductive outcomes., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2018. Published by The Company of Biologists Ltd.)

The system-level identification and analysis of molecular networks in mammals can be accelerated by 'next-generation' genetics, defined as genetics that does not require crossing of multiple generations of animals in order to achieve the desired genetic makeup. We have established a highly efficient procedure for producing knock-in (KI) mice within a single generation, by optimizing the genome-editing protocol for KI embryonic stem (ES) cells and the protocol for the generation of fully ES-cell-derived mice (ES mice). Using this protocol, the production of chimeric mice is eliminated, and, therefore, there is no requirement for the crossing of chimeric mice to produce mice that carry the KI gene in all cells of the body. Our procedure thus shortens the time required to produce KI ES mice from about a year to ∼3 months. Various kinds of KI ES mice can be produced with a minimized amount of work, facilitating the elucidation of organism-level phenomena using a systems biology approach. In this report, we describe the basic technologies and protocols for this procedure, and discuss the current challenges for next-generation mammalian genetics in organism-level systems biology studies.

Discrepancies exist between the preferred temperature range for mice (26 to 32 °C) and current recommendations (20 to 26 °C), which may alter metabolism and negatively affect studies using mice. Previous research indicates that nesting material can alleviate cold stress in mice; therefore, we sought to determine the effects of the amount of nesting material provided (0, 6, or 12 g) on heat energy loss and energy balance in 3 mouse strains housed at currently recommended temperatures during the daytime, a period of presumed inactivity. Groups of BALB/cAnNCrl, C57BL/6NCrl, and Crl:CD1(ICR) mice, balanced by strain and sex, were group-housed and provided 0, 6, or 12 g of nesting material. After a 3-d acclimation period, body weight was determined daily at 0800, food intake was determined at 0800 and 2000, and total heat production was evaluated from 0800 to 2000 on 4 consecutive days and used to calculate energy balance and the respiratory quotient. Although the amount of nesting material had no overall effect on food intake or heat production, mice provided 12 g of nesting material had greater weight gain than those given 0 or 6 g. This increase in body weight might have been due to improved energy balance, which was corroborated by an increased respiratory quotient in mice provided 12 g of nesting material. In summary, although heat production did not differ, providing 12 g of nesting material improved energy balance, likely leading to an increase in body weight during the 0800-2000 testing period.

We reared ICR mice during a growth period (3 to 10 weeks of age) and examined the effect of exercise induction, by enriching the rearing environment with obstacles such as ladders, compared to the standard environment. Environmental enrichment significantly increased the amount of exercise in both sexes (P<0.01). Enriched exercise mice had higher body weight than control mice at 6 to 9 weeks of age in males and 8 weeks of age in females (P<0.05). The sexual maturation of female enriched exercise mice was significantly advanced compared to the control (P<0.001). Enriched exercise mice showed decreased anxiety-like behavior in the open field test and lower plasma corticosterone levels in both sexes compared to the control, and differences were statistically significant in males (P<0.05). In both sexes, enriched exercise appeared to increase natural killer cells in blood compared to the control, but no statistical differences was detected. In conclusion, we confirmed that daily low-stress exercise could be induced using a three-dimensional rearing environment in growing mice. In addition, we suggest that exercise has beneficial effects on physical growth, sexual maturation and anxiety-like behavior. Furthermore, environmental enrichment might be more effective in male than female in group-housed mice.

Morinda citrifolia L. commonly known as noni or Indian mulberry belongs to the family Rubiaceae. Noni fruit juice has recently become a very popular remedy for the treatment of several diseases, including psychiatric disorders. This study aimed to investigate the anticraving effect of Tahitian Noni® Juice (TNJ) against ethanol seeking behavior in ICR male mice using the conditioned place preference (CPP) test. The CPP procedure consisted of four phases: preconditioning, conditioning, extinction, and reinstatement. During conditioning, intraperitoneal (i.p.) injections of ethanol (2 g/kg body weight (bw)) and normal saline (10 ml/kg bw) were given on alternate days for 12 days. Then, the animals were subjected to extinction trials for the next 12 days to weaken CPP. Finally, CPP was reinstated in the extinguished animals by a single low-dose priming injection of ethanol (0.4 g/kg bw, i.p.). The effect of TNJ (as a source of drinking water) on different phases of ethanol CPP in mice was studied. TNJ-treated mice showed a significant reduction in ethanol seeking behavior in the CPP test. The reference drug, acamprosate (ACAM) also showed a similar effect in the CPP test. The outcome of this study suggests that TNJ is effective in attenuating ethanol craving in mice and could be utilized for the treatment of alcohol dependence. Further clinical studies in this direction are warranted to support the present preclinical findings.

Mice are commonly anesthetized intraperitoneally with a ketamine-xylazine (KX) solution. Although this route of administration allows rapid uptake of the injected drugs, its disadvantages and potential risks include pain, peritoneal irritation, and perforation of an abdominal organ; some of the risks depend on the operator's experience. We compared the efficacy of intraperitoneal and subcutaneous administration of KX in HSD:ICR, BALB/cOlaHsd, and C57BL/6JOlaHsd mice in terms of time to onset and duration of surgical anesthesia, procedure safety, and mortality. Male and female mice (n = 20 each sex and strain) were anesthetized by using the same dose of intraperitoneal or subcutaneous KX. Time to onset and duration of immobilization and time to onset and duration of surgical anesthesia according to the pedal reflex differed significantly between strains. Within each strain, the durations of immobilization and surgical anesthesia were comparable between the routes of administration. The sex of the mouse but not the route of administration influenced whether surgical anesthesia was achieved. None of the subcutaneously-injected mice died. After intraperitoneal injections, 30% of the female mice died, compared with 3% of the male. In addition, fewer female mice achieved surgical anesthesia, suggesting a narrow therapeutic window for intraperitoneal KX in female mice. In conclusion, surgical anesthesia of mice with subcutaneous KX (K, 191.25 mg/kg; X, 4.25 mg/kg) seems to be safe, and the subcutaneous route is generally just as effective as the intraperitoneal route. The variability among mouse strains and between sexes requires further investigation to determine the optimal dosage.

Given the pace at which human-induced environmental changes occur, a pressing challenge is to determine the speed with which selection can drive evolutionary change. A key determinant of adaptive response to multivariate phenotypic selection is the additive genetic variance-covariance matrix ( G: ). Yet knowledge of G: in a population experiencing new or altered selection is not sufficient to predict selection response because G: itself evolves in ways that are poorly understood. We experimentally evaluated changes in G: when closely related behavioural traits experience continuous directional selection. We applied the genetic covariance tensor approach to a large dataset (n = 17 328 individuals) from a replicated, 31-generation artificial selection experiment that bred mice for voluntary wheel running on days 5 and 6 of a 6-day test. Selection on this subset of G: induced proportional changes across the matrix for all 6 days of running behaviour within the first four generations. The changes in G: induced by selection resulted in a fourfold slower-than-predicted rate of response to selection. Thus, selection exacerbated constraints within G: and limited future adaptive response, a phenomenon that could have profound consequences for populations facing rapid environmental change., (© 2015 The Author(s).)

Bagaza virus (BAGV) is a mosquito-borne flavivirus belonging to the Ntaya serocomplex. In 2010, a disease outbreak was reported in Cádiz (Southern Spain) affecting game birds (red-legged partridges and common pheasants). In this work, red-legged partridges were inoculated experimentally with infectious BAGV isolated from this outbreak in order to make a complete clinical and analytical assessment of the disease caused by the pathogen in this species. Viral load (by real-time RT-PCR) in blood, oral and cloacal swabs, and feathers, and neutralizing antibody titres (by VNT) were measured. In order to determine direct contact transmission, non-inoculated partridges were caged together with the inoculated ones. To assess infectiousness in other species, house sparrows and mice were also inoculated with the virus. All the inoculated partridges were clinically affected, and 30% of them died. All the infected individuals lost weight, with larger losses being recorded in females. Conversely, no mortality or disease symptoms were observed in the sparrows or mice. Remarkably, all the contact partridges acquired the infection by direct (non-vectored) transmission. This study confirms that the red-legged partridge is a susceptible host for BAGV infection, and that this pathogen is transmitted by direct contact. Long-lasting viral loads detected in calami of immature feathers demonstrate that feather sampling could be a useful strategy in active surveillance programs for early detection of BAGV.

Mice raised in experimental habitats containing an artificial network of narrow "arboreal" supports frequently use hallucal grasps during locomotion. Therefore, mice in these experiments can be used to model a rudimentary form of arboreal locomotion in an animal without other morphological specializations for using a fine branch niche. This model would prove useful to better understand the origins of arboreal behaviors in mammals like primates. In this study, we examined if locomotion on these substrates influences the mid-diaphyseal cross-sectional geometry of mouse metatarsals. Thirty CD-1/ICR mice were raised in either arboreal (composed of elevated narrow branches of varying orientation) or terrestrial (flat ramps and walkways that are stratified) habitats from weaning (21 days) to adulthood (≥4 months). After experiments, the hallucal metatarsal (Mt1) and third metatarsal (Mt3) for each individual were isolated and micro-computed tomography (micro-CT) scans were obtained to calculate mid-shaft cross-sectional area and polar section modulus. Arboreal mice had Mt1s that were significantly more robust. Mt3 cross sections were not significantly different between groups. The arboreal group also exhibited a significantly greater Mt1/Mt3 ratio for both robusticity measures. We conclude that the hallucal metatarsal exhibits significant phenotypic plasticity in response to arboreal treatment due to habitual locomotion that uses a rudimentary hallucal grasp. Our results support the hypothesis that early adaptive stages of fine branch arboreality should be accompanied by a slightly more robust hallux associated with the biomechanical demands of this niche., (© 2015 Wiley Periodicals, Inc.)

Abortion is the major clinical sign of brucellosis in animals but little is known about the underlying mechanisms. This study was designed to evaluate a pregnant mouse model for the vertical transmission of Brucella melitensis using four infectious doses: 10(3) colony-forming units (CFU), 10(4) CFU, 10(5) CFU, and 10(6) CFU. During the experimental period, no instances of abortion were recorded, but stillbirths were observed in the groups infected with doses of 10(4) CFU and higher. Regardless of whether the fetuses were stillborn or alive, transmission of bacteria to the fetus and bacterial replication in the cytoplasm of placental trophoblast giant cells were detected. A higher degree of bacterial colonization was found in the placenta than in the spleen or fetus. Doses of 10(5) CFU of B. melitensis or higher produced a severe, necrotizing placentitis similar to the pathological damage observed in ruminants. The data suggest that experimental murine brucellosis resembles ruminant brucellosis and represents a potential model for studying the pathogenic mechanisms of B. melitensis., (Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.)

The aim of our study was to investigate the effect of maternal obesity on the quality and developmental capabilities of in vivo-derived preimplantation embryos. A two-generation dietary model, based on mice overfeeding during intrauterine and early postnatal development, was used to produce four types of female animals: with physiological (7%-8%), slightly elevated (8%-11%), highly elevated (>11%), and low (<7%) amounts of body fat. Spontaneously ovulating females (5-6 weeks old) were mated with male animals and subjected to embryo isolation at Day 4. Stereomicroscopical evaluation of collected embryos showed that the amount of maternal body fat did not affect the average number of collected embryos per dam. However, significant differences were found in the stage-distribution of isolated embryos: dams with highly elevated body fat and dams with low fat delivered decreased numbers of blastocysts and increased numbers of lower-stage or degenerated embryos compared with dams with physiological or slightly elevated fat value. Fluorescence staining showed that blastocysts isolated from dams with high and low percentage of body fat contained significantly higher numbers of dead cells. Most of such dead cells were of apoptotic origin. In contrast, the amount of maternal body fat did not affect blastocyst growth-the average numbers of cells per blastocyst were comparable in all groups. In conclusion, highly elevated or decreased amount of maternal body fat slowed down the development and negatively affected the quality of naturally in vivo-derived preimplantation embryos. No negative effect of slightly elevated fat was observed., (Copyright © 2014 Elsevier Inc. All rights reserved.)

To date, the most successful and popular vitrification method is based on the minimum volume cooling (MVC) concept, in which embryos are vitrified in a very small volume of vitrification solution (VS) and then stored in cryotubes in liquid nitrogen (LN₂). Unfortunately, these methods need special devices and may not be suitable for vitrifying a large number of embryos. Theoretically, more embryos in VS on a paper (MVC concept) in cryotubes can be vitrified effectively. Therefore, this study directly vitrifies mouse embryos on a Kimwipes tissue in an 1.8 mL cryotube. The ICR 2-celled to blastocyst embryos were used for testing this procedure. In Treatment 1, embryos transferred with 1-2 μL of VS into a cryotube. Treatment 2 was similar to Treatment 1 except that the cryotube was filled with LN₂. Treatment 3 was identical to Treatment 1 except that a small piece (5 mm²) of a sterilized Kimwipes tissue was placed on the top of VS. Treatment 4 was identical to Treatment 3 except for the cryotube being filled with LN₂. After each treatment, the cryotubes were capped and transferred to a LN₂ tank. After warming, the recovered embryos were cultured in KSOM+AA for 1-3 days. There were no differences in the recovery rate, overnight survival rate, blastocyst rate, and birth rate after embryo transfer among all treatment groups. Our results demonstrated an alternative simple, efficient, and mass reproducible method for vitrifying mouse embryos using papers as a vehicle and cryotubes as a container., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Mortality and morbidity of neonates continue to be major problems in humans and animals, and immunoblogulin A (IgA) provides protection against microbial antigens at mucosal surfaces. The present study was conducted to clarify the effects of coumestrol administration to maternal mice during pregnancy and lactation on IgA antibody-secreting cells (ASC) in mammary glands in lactating mice. From 6.5 to 16.5 days post coitus and 1 to 13 days post partum (dpp), maternal mice were administered coumestrol at 200 μg/kg body weight/day. Coumestrol administration increased the number of IgA ASC and the messenger RNA expression of IgA C-region and vascular cell adhesion molecule-1 in mammary glands of maternal mice at 14 dpp, but coumestrol administration had no effect on the number of IgA ASC in the ileum. Coumestrol administration increased serum IgA concentration in maternal mice at 14 dpp, but IgA concentrations in serum, stomach contents, intestine and feces of neonatal mice were not affected by treatment. These results imply that coumestrol administration to maternal mice during pregnancy and lactation is effective in increasing the numbers of IgA ASC in mammary glands during lactation owing to the activated messenger RNA expressions of IgA C-region and vascular cell adhesion molecule-1 in mammary gland., (© 2012 Japanese Society of Animal Science.)

A recently observed developmental instability of the ano-genital distance (AGD) in female mice indicates that natural prenatal androgens do not have such a robust effect on female genital morphology as has been generally assumed. Part of this instability might be caused by oestrous cyclicity. To check this assumption, we examined the effect of the stage of the oestrous cycle on the AGD in adult (61-75 days old) female mice. Consistent with our assumption, the female AGD (1) varied during the oestrous cycle (p < 0.05), indicating thus rapid changes in morphology of female external genitalia, and (2) showed good repeatability (>0.66) in each stage of the oestrous cycle, suggesting that female genital morphology systematically varied within the oestrous cycle. Therefore, the stage of the oestrous cycle should be considered when assessing prenatal masculinization in adult female mice., (© 2012 Blackwell Verlag GmbH.)

The D-galactose (D-gal)-induced animal model, which is established by consecutive subcutaneous d-gal injections for approximately 6weeks, has been frequently used for aging research. This animal model has been shown to accelerate aging of the brain, kidneys, liver, and blood cells. However, aging of the female reproductive organs in this animal model has not been reported. The aim of this study was to investigate changes in the ovary in the d-gal-induced aging mouse model. First, we evaluated anti-Müllerian hormone (AMH) as a marker of ovarian aging in blood plasma. We speculated there would be lower AMH levels in d-gal-treated mice because ovarian aging would be induced by d-gal, as reported for other tissues. However, the results showed that AMH levels in d-gal-treated mice were approximately four-fold higher than control mice. Abnormally high AMH levels are detected in ovarian cancer and polycystic ovary syndrome (PCOS) patients. Therefore, we examined PCOS-related markers in this mouse model. Total testosterone levels were high and abnormal estrous cycles were induced in d-gal-treated mice. These changes, including AMH levels, in d-gal-treated mice were inhibited by aminoguanidine treatment, an advanced glycation end product reducer. In addition, ovarian cysts were observed in some d-gal-treated mice. These results indicate that with respect to female reproduction, d-gal-treated mice are suitable for PCOS studies, rather than aging studies., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Ultrasonographic assessment of fetal growth to estimate fetal weight has been widely used in clinical obstetrics but not in laboratory mice. Even though it is important to assess fetal growth abnormalities for gene-targeting studies using mice, there have been no reports of accurately estimated fetal weight using fetal biometric parameters in mice. The aim of this study was to establish an accurate mouse formula using fetal biometric parameters under ultrasound imaging. Using a high-frequency ultrasound system with a 40 MHz transducer, we measured 293 fetuses of biparietal diameter and mean abdominal diameter from day 12.5 postcoitus (p.c.) until day 18.5 p.c every day. Thirteen algorithms for humans based on head and/or abdominal measurements were assessed. We established an accurate formula based on measurement of the abdomen in Jcl:ICR mice to investigate gestational complications, such as intrauterine growth restriction.

A method for blood collection from the jugular vein of mice without anesthesia was compared with a tail-incision technique. Jugular vein blood collection allowed withdrawal of almost 15% of the circulating blood volume at a time in less than 1 min. Hemolysis, hematocrit, and plasma thrombin-antithrombin complexes (a marker of blood coagulation) were higher in samples collected from the tail vein than the jugular vein. Mice produced similar plasma corticosterone levels after serial blood collection by either method. Tail incision led to a slight but significant increase in C-reactive protein levels. Using the jugular venipuncture technique, we then performed a pharmacokinetic study and an oral glucose tolerance test. Plasma concentrations of levofloxacin, an antimicrobial agent, were dose-dependently elevated after oral administration, and linear increases in C(max) and AUC were observed. We also confirmed that overall glucose excursion is significantly decreased in mice treated with exendin 4, a glucagon-like peptide 1 agonist. These results indicate that the jugular venipuncture is a useful technique from the point of view of no requirement for anesthetics, serial blood collection at short intervals, large volume of blood collection, quality of sample and animal welfare. This technique is of particular interest for studies that examine time-dependent changes in blood variables.

The ovary is the main secretory source of progestin and estrogen and is indispensable to the maintenance of all events of pregnancy in mice. The purpose of this study was to control all processes of pregnancy in mice, from embryo implantation to parturition, without ovaries. The ovaries were removed before embryo implantation, and a single injection of medroxyprogesterone acetate (MPA) was given. Embryo implantation was induced by leukemia inhibitory factor, which can substitute 17β-estradiol (E(2)). Continuous exposure to E(2) was necessary at mid-pregnancy, when placentation was completed. All mice sustained pregnancy without ovaries before parturition, which was initiated by the removal of E(2) and MPA. Murine pregnancy is a complicated process involving embryo implantation, placentation, and parturition. Complete control of pregnancy was achieved with the simple treatment of MPA and E(2) after induction of embryo implantation. Here, time-dependent events in the uterus during pregnancy could be realized without the ovaries, because the initiation of each event could be stringently controlled by hormonal treatments.

The human steroid and xenobiotic receptor (SXR), (also known as pregnane X receptor PXR, and NR1I2) is a low affinity sensor that responds to a variety of endobiotic, nutritional and xenobiotic ligands. SXR activates transcription of Cytochrome P450, family 3, subfamily A (CYP3A) and other important metabolic enzymes to up-regulate catabolic pathways mediating xenobiotic elimination. One key feature that demarcates SXR from other nuclear receptors is that the human and rodent orthologues exhibit different ligand preference for a subset of toxicologically important chemicals. This difference leads to a profound problem for rodent studies to predict toxicity in humans. The objective of this study is to generate a new humanized mouse line, which responds systemically to human-specific ligands in order to better predict systemic toxicity in humans. For this purpose, the ligand binding domain (LBD) of the human SXR was homologously knocked-in to the murine gene replacing the endogenous LBD. The LBD-humanized chimeric gene was expressed in all ten organs examined, including liver, small intestine, stomach, kidney and lung in a pattern similar to the endogenous gene expressed in the wild-type (WT) mouse. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis showed that the human-selective ligand, rifampicin induced Cyp3a11 and Carboxylesterase 6 (Ces6) mRNA expression in liver and intestine, whereas the murine-selective ligand, pregnenolone-16-carbonitrile did not. This new humanized mouse line should provide a useful tool for assessing whole body toxicity, whether acute, chronic or developmental, induced by human selective ligands themselves and subsequently generated metabolites that can trigger further toxic responses mediated secondarily by other receptors distributed body-wide.

We isolated a novel murine norovirus (MNV), MT30-2 strain, from feces of conventional mice in Japan to evaluate the virucidal activity of four antiseptics. The MNV MT30-2 strain was inactivated by as little as 0.2% (w/v) povidone-iodine (PVP-I) and 0.1% (w/v) sodium hypochlorite (NaOCl) treatment as determined by a novel plaque assay. Importantly, PVP-I reduced the MNV titer by 4 log(10) within 15 s of exposure. The other two antiseptics, benzethonium chloride (BEC) and chlorhexidine gluconate (CHG), did not reduce the MNV titer even when treatment lasted for 60 s. When the virus titer was reduced by PVP-I or NaOCl treatment, the amount of MNV RNA was not reduced, indicating that the presence of viral RNA was not related to the virucidal activity of the antiseptics. PVP-I and NaOCl will be useful in controlling the spread of MNV, which is a common problem in mice colonies. In this study, we isolated a novel MNV and newly revealed that two antiseptics (PVP-I and NaOCl) were able to inactivate MNV at low concentrations and in a short contact time.

The origins of liver progenitor cells have been extensively studied, but evidence on the origin of pancreatic precursor cells is currently limited. Pancreatic and duodenal homeobox gene 1 (Pdx1) is one of the earliest known markers for the pancreas. A transgenic mouse line expressing green fluorescent protein (GFP) under the control of the Pdx1 promoter showed that Pdx1/GFP expression was first observed in the mid-region of the anterior intestinal portal (AIP) lip at embryonic day (E) 8.5 at the 5-6 somite stage (ss). The liver progenitors were confirmed to originate from separate domains at the lateral endoderm and the inner part of the medial AIP as previously reported (Tremblay and Zaret, 2005), which turned out to lie caudally to the Pdx1/GFP-expressing domain. To confirm if the early Pdx1/GFP-positive cells give rise to the pancreatic bud, we labeled the cells on the lip of the AIP using the carbocyanine dye CM-DiI and traced their fates in 1-4 ss, 5-6 ss and 7-9 ss E8.5 embryos using an ex utero whole embryo culture method. At 1 ss, the ventral pancreas progenitors were observed in the lateral endoderm, not yet being segregated from the liver or gut progenitors. Cells that contributed solely to the ventral pancreas first appeared at the AIP lip from 5 ss. At 5-6 ss, cells from the medial of the AIP lip contributed to the ventral pancreas. The pancreas fate region become narrower as development progresses. At 7-9 ss, the cells contributing to the ventral pancreas resided in a narrow region of the AIP lip. From 5 ss, the right flanking region contributes to the posterior gut, and the left flanking region contributes to the anterior gut. Dorsal pancreatic progenitors originate from the dorsal endoderm at the 3-6 somite level at 7-9 ss, though they have not yet diverged from the dorsal gut progenitors at this stage., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

The PI3K/Akt signal transduction pathway plays an important role in pre-implantation embryonic development. The tumor suppressor gene PTEN negatively regulates the PI3K/Akt pathway. Although PI3K is constitutively activated during pre-implantation embryonic development, currently no evidence shows the presence and possible involvement of PTEN in early embryo development. We investigated the expression of PTEN protein in germinal vesicle (GV) stage oocytes as well as in pre-implantation embryos. The activated form of PTEN was distributed in the peripheral of GV oocytes and compact morula. Treatment of GV oocytes with PTEN inhibitor bpV(pic) did not affect the maturation of the oocyte, but significantly impaired embryonic development. Thus, our study suggests the necessary role of PTEN in pre-implantation embryonic development.

Hybridomas, generated by fusing myeloma cells with B lymphocytes, secrete monoclonal antibodies (mAbs) specific for an antigen. To establish hybridomas that secrete Mongolian gerbil (Meriones unguiculatus) mAbs, we immunized gerbils with keyhole limpet hemocyanin (KLH) and fused splenocytes from them with a non-secreting mouse myeloma cell line (P3-X63-Ag8.653). We obtained hybridomas that secreted immunoglobulin (Ig) against KLH. These hybridomas had more chromosomes than either parent and retained several gerbil chromosomes. Therefore, these cells were heterohybridomas with both gerbil and mouse chromosomes. They expressed gerbil Ig heavy-chain constant (IGHC) region mRNA, but not mouse gamma (γ) 1 IGHC. SDS-PAGE and Western blot analyses indicated that the cells secreted whole Ig molecules of gerbil origin. Moreover, the cells continued secreting Ig for several months., (Copyright © 2011 Elsevier B.V. All rights reserved.)

MicroRNAs (miRNAs) are a functional small non-coding RNA and play essential roles in gene regulation in development, differentiation and proliferation. In this study, we investigated expression profiles of miRNAs in the process of normal mouse brain growth from embryonic day 16.5 to ~19 months old by means of DNA microarray and reverse-transcription quantitative polymerase chain reaction, and we examined whether there was any association between the expression of miRNAs and brain growth. The results indicated that a major change in the expression of miRNAs occurred in the brain within the first week to the fourth week postnatally. The data also exhibited the miRNAs that gradually increased and decreased in their levels, over the course of brain growth. Therefore, the current study suggests that miRNAs are capable of becoming a useful biological marker for study of brain growth, and leads to the possibility that gene silencing involving miRNAs may participate in the process of brain growth and perhaps brain aging., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Autophagyis, the bulk degradation of proteins and organelles, is essential for cellular maintenance, cell viability, and development, and is often involved in type II programmed cell death in mammals. This study investigated the expression levels of autophagy-related genes and the effect of 3-methyladenine (3-MA, an autophagy inhibitor) or rapamycin (an autophagy inducer) on the in vitro development and apoptosis of mouse embryos. LC3, which is essential for the formation of autophagosomes, was widely expressed in mouse embryos, and high levels of transcript were present from 1 to 4 cells but gradually decreased through the morula and blastocyst stages. 3-MA-treated embryos exhibited significantly reduced developmental rates and total cell numbers, but increased rates of apoptosis. Furthermore, both the expression of Lc3, Gabarap, Atg4A, and Atg4B, and the synthesis of LC3 were significantly reduced at the blastocyst stage. Although rapamycin treatment did not affect developmental rates, cell numbers decreased, and the apoptosis rate increased. Expression of Lc3, Gabarap, Atg4A, and Atg4B, and synthesis of LC3 increased as well. Modulation of Lc3 mRNA and LC3 protein levels using 3-MA or rapamycin significantly increased apoptotic cell death through the disruption of mitochondrial morphology and reduction of mtDNA copy number at the blastocyst stage. Interestingly, the inner cell mass, detected by immunostaining with POU5F1 (OCT3/4) after 3-MA or rapamycin treatment of embryos, was significantly increased compared to controls. These results suggest that autophagy influences developmental patterning and apoptosis, and may play a role in early mouse embryogenesis., (Copyright © 2011 Wiley-Liss, Inc.)

The hypothalamic-pituitary-gonadal (HPG) axis exerts a profound effect on animal development, reproduction, and response to stress, and new insights into its complicated functional activities are continuously being made. In the present study, by using immunohistochemical studies and different mouse models (ovariectomy and ob/ob mice), we systemically analyzed the expression of a novel mitochondria-localized glutamic acid-rich protein (MGARP)/ovary-specific acid protein and demonstrated that MGARP is under the regulation of the HPG axis. MGARP is highly enriched in steroidogenic tissues and the visual system. Interestingly, its expression increases as mice develop. Early in development, MGARP is mainly detected in the retina and adrenal gland. At this early developmental stage, its expression is not detectable in the gonads, but its expression in the gonads dramatically increases during the first 2-4 wk after birth. Importantly, MGARP levels correlate with estrogen levels in the ovaries during the estrous cycle, and estrogen regulates the expression of MGARP in a tissue-specific manner and through a feedback regulatory mechanism. Functional inhibition of GnRH with an antagonist strongly reduces MGARP levels, and knockout of leptin (ob/ob) significantly reduces the MGARP expression in follicular granular cells. We proposed a model that elucidates the role MGARP plays in the HPG axis. Within the HPG axis loop, MGARP participates in hormone biosynthesis while being under the regulation of the hormones derived from the HPG axis.

Functional deficiency of the X-linked methyl-CPG binding protein 2 (MeCP2) leads to the neurodevelopmental disorder Rett syndrome (RTT). Due to random X-chromosome inactivation (XCI), most RTT patients are females who are heterozygous for the MECP2 mutation and therefore mosaic in MeCP2 deficiency. Some MECP2 heterozygote females are found to have unbalanced XCI, which may affect the severity of neurological symptoms seen in these patients; however, whether MeCP2 deficiency affects XCI in the postnatal and adult brain is unclear. Here we developed a novel MeCP2 mosaic mouse model in which the X chromosome containing the wild-type Mecp2 expresses a green fluorescent protein (GFP) transgene, while the X chromosome harboring the mutant Mecp2 does not. Due to random XCI, the neurons in the female MeCP2 mosaic mice express either wild-type MeCP2 (GFP+) or mutant MeCP2 (GFP-), and the two can be distinguished by GFP fluorescence. Using this mouse model, we evaluated XCI in female heterozygote mice from 3 to 9 months after birth. We found that MeCP2 deficiency does not affect XCI at 3 months of age, but does alter the proportion of wild-type MeCP2-expressing neurons at later ages, suggesting that MeCP2 impacts XCI patterns in an age-dependent manner. Given the important function of MeCP2 in neuronal development, our data could shed light on how MeCP2 deficiency affects postnatal brain functions and the dynamic changes in the neurological symptoms of RTT.

We found 6 spontaneous mutant mice with long pelage hair in our ICR breeding colony. The abnormal trait was restricted to long hair in these mice, which we named moja. They were fertile and showed the same growth and behavior as wild-type mice. To investigate the manner of the genetic inheritance of the moja allele, offspring were bred by mating the moja mice; all offspring had long pelage hair. Furthermore, we performed a reciprocal cross between moja mice and wild-type ICR mice with normal hair. All offspring exhibited normal hair suggesting an autosomal recessive inheritance of the trait. The moja/moja hair phenotype was maintained in skin grafted onto nude mice, suggesting that circulating or diffusible humoral factors regulating the hair cycle are not involved in the abnormal trait. The phenotype of moja/moja mice is similar to that of Fgf5-deficient mice. Therefore, we examined the expression of Fgf5 by RT-PCR in moja/moja mice. As expected, no Fgf5 expression was found in moja/moja mouse skin. PCR and DNA sequence analyses were performed to investigate the structure of the Fgf5 gene. We found a deletion of a 9.3-kb region in the Fgf5 gene including exon 3 and its 5' and 3' flanking sequences. Interestingly, the genomic deletion site showed insertion of a 498-bp early transposon element long terminal repeat. Taken together, these results suggest that the long hair mutation of moja/moja mice is caused by disruption of Fgf5 mediated by insertion of a retrotransposon.

Identification and eradication of murine fur mite infestations are ongoing challenges faced by many research institutions. Infestations with Myobia musculi and Myocoptes musculinus can lead to animal health problems and may impose unwanted research variables by affecting the immune and physiologic functions of mice. The purpose of this study was to evaluate the utility and efficacy of soiled bedding sentinels in the detection of fur mite infestations in colony mice. Female young-adult CRL:CD1(ICR) mice (n = 140) were exposed over a 12-wk period to various volume percentages of soiled bedding (11%, 20%, 50%, and 100%) from fur-mite-infested animals. Mice were tested every 2 wk with the cellophane tape test to identify the presence of fur mite adults and eggs. At the end of 12 wk, all mice exposed to 11%, 20%, and 50% soiled bedding tested negative for fur mites. One of the 35 mice (3%) receiving 100% soiled bedding tested positive for fur mites at the end of the 12-wk follow-up period. These findings suggest that the use of soiled bedding sentinels for the detection of fur mite infestations in colony mice is unreliable.

Fur mites are a persistent problem in contemporary laboratory mouse colonies. We conducted several studies to evaluate fur mite diagnostic methodologies and interpretation of results. Retrospective analysis of test results from sentinel mice exposed to soiled bedding collected from colonies infested with Myobia musculi and Myocoptes musculinus revealed the skin scrape test to be more reliable than pelt examination, provided that both the head and dorsal thoracolumbar regions were sampled. To assess their diagnostic accuracy, 3 commercial laboratories were sent positive control slides containing mites, mite parts, or eggs in sets of slides containing diagnostic skin scrapings in varying ratios. Laboratory B correctly identified the positive control slide. Laboratory A identified 1 of 3 positive control slides, whereas laboratory C failed to identify both positive control slides submitted. To determine the time required for a mouse to shed its entire hair coat, fur of Crl:CD1(ICR), BALB/cAnNCrl, and Crl:CFW(SW) albino mice was dyed black and the presence of dyed fur evaluated monthly for 8 mo. Limited dyed hair was still present at 8 mo; therefore, finding eggs or egg casings many months after treatment cessation does not necessarily imply treatment failure. To evaluate the effectiveness of soiled bedding sentinels for detection of fur mites in a mite-infested colony, we exposed naïve mice to varying amounts (100%, 50%, 25%, 2.5%, and 0%) of soiled bedding in clean bedding. As little as 2.5% soiled bedding resulted in detection of a positive sentinel within a 2-mo period.

Objective: To investigate the difference of hypaconitine concentration in serum between normal and cold-deficiency mice after administration of aconite decoction. To analyze how the toxic dose of aconite decoction correlate to the metabolic environment., Method: Prepared cold-deficiency mice model, treated normal and cold-deficiency mice with aconite decoction for 14 days continuously, and then detected hypaconitine concentration in serum by HPLC along with survival ratio of mice on the first, seventh and fourteenth day., Result: After administration of aconite decoction for 14 days, the hypaconitine concentration in serum of cold-deficiency mice is close to that in normal mice. It showed aconite decoction has the ability of regulating metabolism environment, the hypaconitine concentration in serum of normal mice was higher on the seventh and fourteenth day than that on first day. It showed that aconite decoction can disturb metabolism environment of normal mice. It was also been observed that the range of variation of hypaconitine concentration in cold-deficiency mice was minor than that in normal mice during the fourteen days' administration., Conclusion: The difference of serum concentration in normal and cold-deficiency mice showed that there were different metabolic environments in two mice models, and the metabolic environment changed during administration. These results showed that the different toxic doses of aconite decoction were partially due to the different metabolic environments.

Objective: Factor VIII( FVIII) gene knockout mouse model was established for further study on the treatment of hemophilia A., Methods: Exons 16-19 of the mouse FVIII gene were knocked out by ET clone, ES homologous recombination and tetraploid embryo compensation technology. PCR, reverse transcriptase-PCR(RT-PCR) and immunohistochemistry were used to detect the transcription and translation pattern of FVIII. The phenotype of the knockout mice was analyzed by examining the activated partial thromboplastin time (APTT) and FVIII activity (FVIII:C)., Results: PCR, RT-PCR and immunohistochemistry confirmed that FVIII was deficient in the FVIII gene knockout mouse. The APTT results showed that FVIII-deficient mouse plasma had a prolonged clotting time compared to normal mouse plasma. The FVIII:C in heterozygous, hemizygous and homozygous mice was 80%, 8% and 10% of that in normal mice, respectively., Conclusion: The phenotype of the FVIII gene knockout mouse appears grossly similar to that of human with hemophilia A. Establishment of this model may promote the development of new technologies of treatment to hemophilia A.

Yellow KK mice carrying the 'yellow obese' gene Ay are a well established polygenic model for human non-insulin dependent diabetes mellitus. These animals develop marked adiposity and decreased glucose tolerance relative to their control littermates, KK mice. The authors monitored glucose tolerance in KK-Ay mice over time and observed a significant (P

The fine-branch niche is a natural setting found among the slender vines and terminal branches of shrubs and tree canopies. In this study, the authors designed two simulations of this setting for laboratory mice. Their main goal was to model phenotypic plasticity in a small, clawed mammal, in order to better understand the effect of a thin-branch arboreal setting on musculoskeletal growth and behavior of these animals. The authors exposed mice to the smaller climbing setting for limited amounts of time (e.g., 30 min) and used the larger setting to permanently house another group of mice. Mice in both the limited and continuous climbing groups succeeded at quadrupedal climbing among a complex of thin branch segments. This led the authors to postulate that similarly sized pre-primates that lacked the unique features of today's primates could potentially have exploited this niche. The mice housed in the continuous model remained healthy and showed no signs of aggression, leading the authors to suggest that animal care personnel could use similar models as forms of enrichment for laboratory mice.

Animal facilities generate a large amount of used bedding containing excrement as medical waste. We developed a recycling system for used bedding that involves soft hydrothermal processing. In this study, we examined the effects of bedding type on growth, hematologic and serum biochemical values, and organ weights of female and male mice reared on either recycled or fresh bedding from 3 to 33 wk of age. Neither growth nor physiology differed between mice housed on recycled bedding compared with fresh bedding. When 14-wk-old mice were bred, litter size and total number of weaned pups showed no significant differences between animals raised on recycled or fresh bedding. Because bedding type influences the environment within cages and animal rooms, we evaluated particulate and ammonia data from cages and animal rooms. Values were significantly lower from cages and rooms that used recycled bedding than from those using fresh bedding, thus indicating that recycled bedding has the potential to improve the environment within both cages and animal rooms. Overall, this study revealed that recycled bedding is an excellent material for use in housing laboratory rodents. Specifically, recycled bedding may reduce medical waste and maintain healthy environments within cages and animal rooms.

Neurogenesis in the adult hippocampus is differentially influenced by the genetic background. We examined the differences in Ki-67 (a proliferating cell marker) and doublecortin (DCX; an immature progenitor cell marker) immunolabelling in the dentate gyrus (DG) of the adult hippocampus in three strains of mice (ICR, C57BL/6, and BALB/c) to evaluate the effect of genetic background on adult hippocampal neurogenesis. All strains showed constitutive immunoreactivity of either Ki-67 or DCX in the DG of the adult hippocampus. C57BL/6 mice showed significantly higher levels of Ki-67-immunopositive cells in the subgranular zone (SGZ) of the DG (approximately 2.2-fold) compared to ICR and BALB/c mice. The greatest number of DCX-immunopositive cells was found in C57BL/6 (approximately 1.6-fold), which differed significantly from ICR and BALB/c mice. However, there was no significant difference in the number of Ki-67- and DCX-immunopositive cells between BALB/c and ICR mice. Genetic differences with respect to certain aspects of hippocampal neurogenesis in adult mice may influence hippocampal functions, including learning and memory.