The gracile axonal dystrophy (gad) mice are known to have a deletion within the gene encoding ubiquitin carboxy-terminal hydrolase-1 (Uch-L1) and show hereditary sensory deterioration and motor paresis. Expression of Uch-L1 is reported to be almost limited to the nervous system and testis. To understand whether Uch-L1, one of the major ubiquitin carboxy-terminal hydrolase (UCH) isozymes in the testis, affects spermatogenesis and other UCH isozymes (Uch-L3, L4 and L5) expression in the testis, we compared the testis between gad, hetero and wild type mice by histological, immunohistochemical analyses and RT-PCR. Histological analysis in 25-week-old gad mice showed shrinking of seminiferous tubules, decreasing total number of cells and enlargement of remaining cells in seminiferous tubules. By immunohistochemistry, a significant decrease (p<0.05) in the number of proliferating cell nuclear antigen (PCNA) positive cells was observed. Expression of other UCH isozyme mRNAs was not apparently affected by Uch-L1 deficiency in 25-week-old gad mice. This study is the first report on the testis of gad mutant mouse.

抄録全体を表示

The preference of guinea pigs for bedding materials, wood shavings (WS) or paper cutting sheets (PS), was studied. Animals aged 8 weeks and 20 weeks showed a similar behaviour pattern during 30 min in the light, preferring WS to PS regardless of ages. Over both light and dark periods for 24 h, guinea pigs apparently preferred WS in the light, spending much more time resting in them than in PS. In the dark, the border-crossing was significantly more frequent than in the light, and the staying time was rather longer in PS than WS. The results suggest that guinea pigs prefer different bedding materials under light and dark conditions.

抄録全体を表示

Marking behavior, marking-like behavior [3] , and changes of the scent glands were observed in aged Mongolian gerbils. In Experiment 1, changes in the marking and marking-like behavior with aging were evaluated in adult male and female Mongolian gerbils of an inbred strain aged 6 to 36 months. The frequency of marking behavior in males was significantly higher than females throughout the observation period except at 36 months of age. On the other hand, frequency of marking-like behavior in males, but not in females decreased with aging, significantly. In Experiment 2, changes of the scent gland in adult males and females aged 6 to 36 months were morphologically evaluated. Macroscopic examination revealed an increase in the size length and width of the glands of males aged 12 months and females aged 6 months. Histologically the glands of all the males and females aged 6 months developed moderately or well. Some of the 12-month-old males and females showed acinar atrophy of the glands, and all the females aged 18 months or more had highly atrophied scent glands. From these results, we concluded that there is no relationship between the changes of marking behavior and those of the scent glands in aged male Mongolian gerbils, and assume that marking behavior in aged animals does not have an important meaning as marking. In Experiment 3, marking and marking-like behavior in castrated adult Mongolian gerbils aged 16 weeks were observed. The result showed that marking behavior, not marking-like behavior was inhibited after castration. From these findings, we consider that generally marking behavior in Mongolian gerbils consists of androgen-dependent marking behavior and androgen-independent marking behavior (marking-like behavior).

抄録全体を表示

A recombinant nucleocapsid protein of Hantaan virus (HTN) 76-118 strain expressed in E. coli was applied as a serodiagnostic antigen in an enzyme-linked immunosorbent assay (rHTN-ELISA) for detection of hantavirus antibody in rat sera. The sensitivity and specificity of the rHTN-ELISA were compared with those of the indirect immunofluoresent assay (IFA) using virus-infected cells. The sensitivity of rHTN-ELISA was similar to that of the IFA both in experimentally SR-11 infected rat and naturally infected rat sera. Sera showing a low antibody titer in IFA and suspected to be negative by other methods were also found to be negative in rHTN-ELISA. These results indicate that rHTN-ELISA is effective as a screening method for serodiagnosis of hantaviruses, because of its high sensitivity, specificity, safety and suitability for processing large number of samples.

抄録全体を表示

A new beige-like coat color mutant was identified in the ACI/N rat colony. Other features characteristic of beige mutants, such as giant granule cells in various tissues, and prolonged bleeding time were also observed. The genetic complementation test, mating beige-like mutant with the authentic beige mutant rat, DA/Ham-Lyst^bg, revealed that the mutant gene is allelic to Lyst^bg. The new beige mutant allele was denoted Lyst^bg-Kyo. Molecular genetic analysis revealed deletion of exons 28, 29, and 30 of the Lyst gene owing to recombination between L1 elements in the mutant rats. Although the deletion was similar to that identified in DA/Ham-Lyst^bg rats, the putative deletion break points in L1 elements were different in the two strains. Further characterization of the ACI/N-Lyst^bg-Kyo rats should make it useful as an animal model for human Chediak-Higashi syndrome.

抄録全体を表示

Quantitative trait locus (QTL) analysis of serum insulin, triglyceride, total cholesterol and phospholipid levels at 10 weeks of age was performed in 321 F₂ offspring from SM/J and A/J mice. Interval mapping revealed a total of 22 suggestive QTLs affecting the four traits: two insulin QTLs on Chromosomes (Chrs) 6 and 8; six triglyceride QTLs on Chrs 4, 8, 9, 11, 12 and 19; six total-cholesterol QTLs on Chrs 1, 3, 4, 14, 17 and 19; and eight phospholipid QTLs on Chrs 2, 3, 4, 6, 8, 10 and 19. Gender influenced the expression of eight of the suggestive QTLs. The total-cholesterol QTLs on Chrs 4, 14 and 17, the triglyceride QTL on Chr 9 and the phospholipid QTL on Chr 4 were specific to females. The phospholipid QTLs on Chrs 2 and 6 and the insulin QTL on Chr 8 were specific to males. In addition, common QTLs involved in the regulation of some of the traits were identified. The female-specific QTL on Chr 4 appeared to be involved in the regulation of total cholesterol and phospholipid levels. The QTL on Chr 8 affected insulin and phospholipid levels, whereas the Chr 19 QTL was common to the three lipid parameters.

抄録全体を表示

Studies were conducted in C57BL/6N Crj male mice and in cultured hepatocytes to clarify the relationship between galactosamine (GalN) induced apoptosis and [Ca²⁺]i kinetics. Chlorpromazine (CPZ), a Ca²⁺-calmodulin antagonist, and verapamil (VR), a Ca²⁺-channel blocker each inhibited GalN-induced DNA fragmentation and the appearance of apoptotic bodies. The kinetics of calcium uptake were evaluated using a calcium analyzer with the acetoxymethyl ester of fura-PE3 (fura-PE3/AM, 2.5 M) as the calcium reporter. An increase in [Ca²⁺]i was detected in the cultured hepatocytes within 3 hours after treatment with 20 mM GalN; this increase was inhibited by pretreatment with either 20 M CPZ or 30 M VR. Ca²⁺ imaging by confocal laser scanning microscopy showed that increase in [Ca²⁺]i after treatment with GalN was initially localized around nuclei, while [Ca²⁺]i signals were later diffuse and observed throughout the cytoplasm. The activities of lactate dehydrogenase (LDH) and serum glutamate-pyruvate transaminase (sGPT), used as indicators of plasma membrane damage and leakage, however, were not reduced by pretreatment with CPZ or VR. From these findings, we infer that the DNA fragmentation in GalN-induced hepatocyte apoptosis is associated with an elevation in the perinuclear concentration of Ca²⁺, but GalN-induced necrotic cell death is triggered through pathway(s) that are insensitive to blockage of Ca ²⁺ influx and therefore appear to occur independently of elevation in [Ca²⁺]i. These results help to clarify the role of calcium flux in hepatocyte apoptosis and necrosis induced by exposure to hepatotoxins in vivo and in vitro.

抄録全体を表示

A new mutant, the Wakayama epileptic rat (WER), exhibiting both spontaneous absence-like behavior and tonic-clonic convulsions, was identified in a colony of Wistar rats. To determine clear seizure characteristics of this mutant strain, we analyzed the mode of inheritance of the convulsion and observed patterns of electroencephalogram (EEG) during the seizures. F1 progeny were produced between the founder male and normal females of the same colony. Animals were monitored through the inbreeding course to analyze genetic control of epileptic behavior. EEGs were recorded using affected animals in the F_3-4 and post F₁₃ generations. After the F₂ generation, affected rats spontaneously exhibited both absence-like immobile behavior and tonic-clonic convulsions. The absence-like seizures were characterized by motor arrest and head droop. The tonic-clonic convulsions began with neck and forelimb clonus, wild jumping/running, and opisthotonic posturing, and evolved to tonic, then clonic convulsions. Most convulsion onsets occurred between 25-70 days of age. Mating experiments revealed that 0%(0/18) of the animals in F₁, 10%(3/26) in F₂, 17%(1/6) in backcross progeny and 86% (100/116) in progeny of crosses between epileptic rats showed tonic-clonic convulsions. Ictal cortical EEGs were characterized by 4-6 (5.1 0.4, mean SD) Hz spike-and-wave complexes in the absence-like seizures and by low-voltage fast waves in the tonic-clonic convulsions. This new mutant rat spontaneously exhibited both absence-like and tonic-clonic seizures. The tonic-clonic seizure was inherited as an autosomal recessive trait with 86% incidence. Thus, the new mutant rat may become a useful model for studying human inherited epilepsies.

抄録全体を表示

The developmental response of in vitro fertilized embryos to oxygen and amino acids were compared between in-house bred C57BL/6JNrs (Nrs) and commercially available C57BL/6JSlc (Slc) mice. Under 20% oxygen, the percentage of embryos that developed to blastocysts and expanded blastocysts, and nuclear numbers were lower in Slc embryos than in Nrs embryos. Moreover, the nuclear number did not increase in Slc embryos during 72-96 h culture. Effects of amino acids were beneficial on development of Slc embryos under 20% oxygen, but inhibitory on blastocoel formation at 78 h under 5% oxygen. On the other hand effects of amino acids on Nrs embryos were observed in nuclear number at 72 and 78 h culture under 5% oxygen. Because the present study showed differences in sensitivity to culture conditions between the C57BL/6J substrains, care must be taken in embryo manipulation of this inbred strain in studies of embryo development or other studies.

抄録全体を表示

It has been suspected that embryos stored in liquid nitrogen tanks may become contaminated with murine pathogens, if some pathogens had been introduced to the tanks accidentally. To examine this, we stored tubes containing embryos with tubes containing mouse hepatitis virus (MHV) or Pasteurella pneumotropica in liquid nitrogen tanks and examined whether progeny mice derived from the embryos were contaminated with the pathogens or not. After storing for 6 months or 1 year the frozen embryos were thawed and implanted into the oviducts of pseudopregnant female mice, and the mice were bred in vinyl isolators. We could not detect serum antibodies to MHV and isolate Pasteurella pneumotropica in the progeny mice, suggesting that cross-contamination between tubes in a liquid nitrogen tank scarcely occurs.

抄録全体を表示

The vermiform appendix-like organ (VALO) of the slow loris was investigated for its histology and immunohistochemical characteristics. The VALO has a much thinner wall with flat folded mucosa and shallower crypts than the cecal mucosa, while cellular components and population of the mucosa were similar to those of the cecum. No coalescent lymph nodules were seen in the submucosa. Immunohistochemically 5-HT-positive cells in the crypts and CD3- and CD8-positive lymphocytes in the lymph nodules were shown in the VALO as well as in the cecum. These findings suggest that the VALO is a low-differentiated vermiform appendix of the slow loris.

抄録全体を表示

Spontaneous development of dermatitis in DS-Nh mice under specific pathogen-free conditions was examined to verify the hypothesis [Exp. Anim. 46: 225-229, 1997] that Stapylococcus aureus (S. aureus) infection is causally associated with the dermatitis. Observation of the mice up to 28 weeks of age indicated that obvious dermatitis does occur under S. aureus-free conditions, though the incidence was low (six of 42 females and two of 90 males). Skin lesions in the absence of this bacterium showed histological changes very similar to those that can be observed under conventional conditions. In addition, hyperproduction of serum IgE was demonstrated in the dermatitis-positive mouse. These findings suggested that the dermatitis is triggered by IgE-mediated allergic reactions.

抄録全体を表示

We previously showed that an intraperitoneal infection with mouse hepatitis virus (MHV) resulted in acute hepatic failure accompanying extremely elevated viral growth in the liver in interferon-γ-deficient BALB/c (BALB-GKO), but not C57BL/6 (B6-GKO) mice. To examine the basis of the strain difference against MHV infection in interferon-γ-deficient mice, viral replication in primary hepatocyte cultures from BALB/c and B6 mice with or without the IFN-γ gene was compared in vitro. The MHV replication in BALB/c hepatocytes with or without the IFN-γ gene was significantly higher than that in B6 hepatocytes with or without the IFN-γ gene, suggesting that there is a strain difference in MHV replication in hepatocytes. Since a significant difference in MHV replication in hepatocytes was not observed between wild type and IFN-γ-deficient mice of the same genetic background, the phenomenon is thought to be independent of IFN-γ. However, pretreatment of hepatocytes with recombinant mouse interferon-γ inhibited MHV replication in a dose-dependent fashion. The results are discussed with respect to the pathology of MHV infection in mice with or without the IFN-γ gene.

抄録全体を表示

The authors studied the physiological and behavioral responses during sexual behavior in female rats. For this purpose, electrocardiographs were recoded from conscious and unrestrained females using a radiotelemetry system. Heart rate during sexual behavior rose sharply following the introduction of a sexually active male, displayed a peak level of 425 bpm during male ejaculation, and then rapidly decreased. This pattern of heart rate in females before and after receiving ejaculation was similar to that in males before and after ejaculation. In the rate of decrease in heart rate, however, there was a significant difference between females and males. The present study is the first to show changes of heart rate during sexual behavior in female rats.

抄録全体を表示