Protocadherin-15 (Pcdh15) plays important roles in the morphogenesis and cohesion of stereocilia bundles and in the maintenance of retinal photoreceptor cells. In humans, mutations in PCDH15 cause Usher syndrome type 1F (USH1F) and non-syndromic deafness DFNB23. In mice, repertories of Pcdh15 mutant alleles have been described as Ames waltzer mutations. For further understanding of Pcdh15 function in vivo and to develop better clinical treatment for the disabling symptoms of USH1F and DFNB23 patients, animal models suitable for clinical as well as pharmacological studies are required. Here we report the characterization of a Pcdh15 mutant allele, Kyoto circling, (Pcdh15^kci) in the rat. Rats homozygous for Pcdh15^kci display circling and abnormal swimming behaviors along with the lack of an auditory-evoked brainstem response at the highest intensities of acoustic stimulation. Positional cloning analysis revealed a nonsense mutation (c. 2911C>T, p. Arg971X) in the Pcdh15 gene, which is predicted to result in the truncation of the PCDH15 protein at the 9th domain of cytoplasmic cadherin domains. Histological study revealed severe defects in cochlear hair cell stereocilia, collapse of the organ of Corti, and marked reduction of ganglion cells in adult Pcdh15^kci mutants. Severe reduction of sensory hair cells was also found in the saccular macula. Since the rat is more advantageous for clinical and pharmacological studies than the mouse, the KCI rat strain may be a better disease model for Pcdh15-deficit USH1F and DFNB23.

View full abstract

Laboratory animals generally experience numerous unfamiliar environmental and psychological influences such as noises, temperatures, handling, shaking, and smells during the process of air transportation. To investigate whether stress induced by air transportation affects stress-related factors in animals, the levels of hormone and chaperone protein were measured in several tissues of F344 rats transported for 13 h and not transported. Herein, we conclude that the levels of corticosterone, HSP70, and GRP78 were significantly increased in the transported group compare to not transported group, but they were rapidly restored to the not transported group level after a recovery period of one week. However, the magnitude of induction and restoration levels of these factors varied depending on the tissue type. Thus, these results suggest that air transportation should be considered for the improvement of laboratory animal health and to reduce the incidence of laboratory animal stress.

View full abstract

Several investigators have used murine models to investigate the pathophysiology of brain ischemia. The focal ischemic model is a closer approximation to human stroke which includes a necrotic core, penumbra, and undamaged tissue. Occlusion of a unilateral artery, especially the middle cerebral artery (MCA), is performed in this model, but collateral circulation often induces variation of ischemic lesions both qualitatively and quantitatively. It is likely that the more proximal the artery which is unilaterally occluded is, the more inconsistent the outcomes. The present study was designed to examine the reproducibility of infarct lesion by distal or proximal artery occlusion. Direct occlusion of the distal MCA was performed and compared with unilateral common carotid artery occlusion (CCAO) in C57BL/6 mice. Direct MCA occlusion (MCAO) consistently induced ischemic lesions in cortical areas. All model animals (n=14) survived 24 h after occlusion, and exhibited a maximum infarct volume (20.0 ± 5.0%). In contrast, permanent and transient unilateral CCAO models had mortality rates of 62.5 and 25.0%, and showed severe to absent lesions with the infarct volumes of 29.0 ± 20.8 and 33.2 ± 24.2%, respectively. In conclusion, distal MCAO produces high reproducibility of ischemic insults and survivability compared to unilateral CCAO. Thus, distal MCAO is a useful method for the focal ischemic model.

View full abstract

The house musk shrew Suncus murinus (Insectivora, Soricidae) is referred to as suncus in a laboratory context. Although the capture of albino-like shrews (wild suncus) has been reported previously, albino-like strains have never been established, and the molecular basis of the character has remained elusive. We have established an OCAO mutant strain (oculocutaneous albinism Okinawa), from a wild suncus with a white coat and red eyes, which was captured in 2002. During the course of establishing the strain, it was revealed that the albino-like phenotype was inherited in an autosomal recessive manner. To elucidate the molecular basis of this phenotype, we cloned the suncus cDNAs for tyrosinase (Tyr), pink-eyed dilution (p), and solute carrier family 45, member 2 (Slc45a2), since these genes are involved in oculocutaneous albinism in various species, including humans. Several polymorphisms were identified in these genes; however, linkage analysis excluded the involvement of Tyr and p. On the other hand, two amino acid substitutions (V240A and G366E) were identified in Slc45a2 that cosegregated with the phenotype in the OCAO mutant strain. While V240A was also present in colored suncus collected from Okinawa, G366E was unique to the albino-like suncus and heterozygous carriers. Thus, we conclude that a mutation in Slc45a2 (G366E) is responsible for an albino-like phenotype in Suncus murinus.

View full abstract

At 0.8 cm of crown-rump length (CRL) in sexually undifferentiated cat fetuses, the Wolffian duct is already observable on the ventro-lateral side of the mesonephros. At 1.2 cm CRL, the anlage of the Müllerian duct growing caudally in close parallel with the Wolffian duct was first observed. At 2.8 cm CRL in sexually differentiated fetuses, the Müllerian duct reached the urogenital sinus but remained indiscernible. Subsequently, at 3.2 cm CRL, regression of the upper part of the Müllerian duct was visible in males, while both ducts continued to grow in females. This suggests that the Müllerian inhibiting substance is produced before 3.2 cm CRL. At 7.0 cm CRL, male and female Wolffian ducts were reduced in diameter by about 50%, accompanied by involution of the mesonephros. Thereafter, the Wolffian duct was retained in the male; however, at 8.5 cm CRL in the female, the Wolffian duct was greatly reduced, by about 80% in diameter, then disappeared completely at 9.0 cm CRL.

View full abstract

The first trial in the developmental phase of the "Performance Evaluation Program" based on the new programs of the International Council for Laboratory Animal Science (ICLAS) was carried out. ICLAS supplied test samples to each diagnostic laboratory for self-assessment of microbiological monitoring methods. We found that 1 mouse serum sample was positive for mouse minute virus and another was positive for Mycoplasma pulmonis antibodies, and 1 rat serum sample was positive for Sendai virus antibody. Mouse parvovirus was detected from mouse spleen and mesenteric lymph node homogenate, and Helicobacter spp. were detected from mouse feces. Corynebacterium bovis was isolated from a mouse skin sample. These results were in agreement with those notified by the ICLAS after the trial. After this trial, the program will eventually be made available to all diagnostic laboratories willing to participate in it.

View full abstract

A female DBA/2 mouse is characterized by the presence of abundant cytoplasmic granules in the renal tubules. In the present study, the morphometrics of kidneys from female DBA/2 mice at 5, 15, 18, 21, and 24 months of age were investigated to determine the age-dependent renal changes in this mouse strain. Glomerular and tubulointerstitial disease progressed with age, and the semiquantitative scores of these lesions showed significant increases. Granules were observed in the proximal straight tubules and no changes were observed in their localization, fine structure, and quantitative scores. It was concluded that the tubular cytoplasmic granules in the female DBA/2 mouse were not affected by age-dependent functional reduction of the kidney.

View full abstract

Vitamin B₁₂ (VB₁₂) was investigated for its ability to influence the expression of genes required for cardiac cell differentiation from mouse embryonic stem cells. When VB₁₂ (0.5 mM) was added to the medium on day 3 of culture, the levels of Cx40 and HCN4 expression increased over those in the control, 2 to 3 days before the start of cardiomyocyte beating. In contrast, the expression levels of α-MHC, MLC-2a, and MLC-2v were almost the same as those of the control throughout the culture period. Our results suggest that VB₁₂ is involved in the promotion of the intercellular conducting system rather than the generation of contractile proteins.

View full abstract

Feeding behavior is regulated by feeding-related peptides in the hypothalamus. The neurons of the arcuate nucleus (ARC), which produces feeding-related peptides, develop and function by three weeks of age in rodents. Because rodents are weaned at three weeks, we studied whether the process of weaning is involved in the development of ARC neurons using monosodium glutamate. Rat pups injected neonatally with monosodium glutamate ingested a large amount of mother's milk at weaning. Monosodium glutamate treatment induced a decrease in the number of ARC cells and mRNA levels of neuropeptide Y and agouti-related protein in the hypothalamus. The alteration of milk consumption following monosodium glutamate treatment appears to cause failure of ARC neuron development and neuropeptide expression.

View full abstract

The effects of long-term treatment with Nanpao, a kampo medicine, on cold constitution were evaluated in aged female rats. Five-month-old rats were administered Nanpao orally at doses of 0, 30, or 100 mg/kg/day. The peripheral blood flow and surface skin temperature in the hind paws were measured using a laser Doppler blood flow meter and infrared thermography, respectively. In animals treated with Nanpao, the peripheral blood flow increased dose-dependently compared to that in the control group. Moreover, the surface skin temperature after immersion in ice-cold water was higher in the Nanpao-treated groups than in the control group at all measurement times. These results suggest that Nanpao has the potential to improve cold constitution associated with decreased peripheral blood flow in women.

View full abstract