Cataract causing lr2 gene is found in the CXSD mouse, which is a recombinant inbred strain of BALB/c and STS mice. For the process of positional cloning of lr2, several candidate genes were selected in the middle region of chromosome 14, but most of them were excluded by combination of recombination and homozygosity mapping. Components of neurofilament proteins, neurofilament light polypeptide (Nefl) and neurofilament3 medium (Nef3), were linked to D14Mit87 which was not separated from the lr2 locus in the homozygosity mapping. When the expression levels of Nefl and Nef3 in eyes were compared in CXSD and BALB/c mice, there were no differences in expression levels. The cDNA sequences of the two genes from CXSD, BALB/c and STS mice were subsequently compared. Several nucleotide differences in cDNA sequences were detected between the mice strains but the majority of the changes were silent mutations that did not alter the amino acids. The sole amino acid difference, E567K in the glutamate rich region of Nfm, between BALB/c and CXSD was found to be a simple genetic polymorphism because the same substitution existed in STS, a non-cataract mouse strain. Therefore we excluded Nefl and Nef3 from the candidate genes for lr2 based on expression and mutation analyses.

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This study investigated the effects of pair housing on diurnal rhythms of heart rate and autonomic nervous activity in miniature swine. For this purpose, six adult Göttingen miniature swine were initially housed individually in an animal cage. Then, two of each swine were housed in a large cage together for 3 weeks. After that swine were separated into individual cages again. During this experimental procedure, electrocardiogram (ECG) was recorded with a Holter ECG recorder. Autonomic nervous activity was evaluated by power spectral analysis of heart rate variability. Heart rate and autonomic nervous activity clearly showed a diurnal rhythm in miniature swine housed in individual cages. When two swine were housed together, heart rate was significantly increased throughout the day and diurnal rhythm disappeared. Although these changes gradually recovered to basal levels, these parameters had not completely returned to basal levels even after 2 weeks. Heart rate was still higher than the initial level just after swine were re-housed in their own individual cages. Heart rate and autonomic nervous activity returned to basal levels about 2 weeks after re-housing. Further, heart rate in some swine decreased below their initial levels. These results suggest that it takes miniature swine at least 2 weeks to adapt to different circumstances. Furthermore, the power spectral analysis of heart rate variability can be used as a useful method in a study for answering controversial issues related to stress response.

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Transgenesis using large DNA such as YAC or BAC has extended the range of applications in functional genomics. Here we describe an efficient BAC transgenesis protocol using a simple BAC DNA preparation method adopted from YAC DNA purification methods. This method allowed us to isolate BAC DNA from small scale culture of BAC-containing cells in sufficient quantity and purity for microinjection. More than 40 founders have been produced with linearized BAC DNA prepared by this method, and 85% of them contained intact BAC transgenes. In contrast, when circular BAC DNA was injected, an approximately three-fold reduction of transgene integration rate was observed and fewer intact transgene integrations were obtained. A line of transgenic mice carrying a 170-kb BAC clone generated in this way successfully rescued tail and embryonic lethality phenotypes of the mouse Brachyury (T) mutants, further demonstrating the utility of this method in functional analysis of the mouse genome.

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Many hematological and immunological parameters remain unclear in the study of the guinea pig. In this study, we established the mean values of blood counts, the percentage of leukocyte fractions and lymphocyte subsets in blood and various lymphoid tissues of the guinea pig with a flow cytometric procedure using MIL4/SSC. The mean counts of WBC and RBC in the blood were lower, and MCV and MCH were higher than those of other rodents, resembling those of humans. Furthermore, the mean percentages of blood lymphocytes were smaller and that of granulocyte was larger than those of other rodents, resembling those of humans. We further established a flow cytometric procedure for lymphocyte subsets and clarified the mean percentages of T- and B-cells, CD4⁺-, CD8⁺- and MHC Class II⁺- T-cells, and CD4^-CD8 ^- T-cells. The latter were morphologically larger in cell size and cytoplasm than CD4⁺- plus CD8⁺ T-cells, and this subset had a significantly higher percentage in newborn animals. Furthermore, the appearance of the MHC Class II⁺ T-cell subset was suggested to be a marker of hyper-activation of T-cells in BCG-immunized animals. Thus, both the novel flow cytometric procedure for leukocyte fractions and lymphocyte subsets, and the established normal values will be useful tools in studying guinea pigs as models of various diseases and biological phenomena.

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Minipigs have been studied as a model of osteoporosis. However, little information is available regarding their bone physiology. We established standardized bone data and investigated the relationship between bone growth and bone metabolism in female minipigs. Blood and urine samples were obtained from 53 female Göttingen minipigs, 3-76 months of age, for measurement of bone biomarkers (i.e., BAP, OC, NTX, and DPD). The lumbar vertebra and femur were excised to determine the growth plate condition, bone length, bone mineral content (BMC), and bone mineral density (BMD). High levels of bone biomarkers were observed during the initial period after birth, decreasing thereafter with age. Bone biomarkers were confirmed to be highly correlated with age (R² > 0.7). The growth plates of the lumbar vertebra and the femur began to close at 21 and 25 months of age, respectively, and closed completely at 42 months of age. Bone length increased rapidly before growth plate closure, and reached a peak at 21 and 28 months of age in the lumbar vertebra and the femur, respectively. The levels of BMC and BMD increased rapidly before growth plate closure, and continued to increase slowly until 76 months of age. A high negative correlation (-0.855 < r < -0.711, p<0.001) was confirmed between the bone biomarkers and the bone measurement data. These results indicate that the bone turnover velocity is consistent with the bone growth velocity in female Göttingen minipigs.

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Recently, we developed myocardial infarction-prone WHHLMI rabbits from coronary atherosclerosis-prone WHHL rabbits (WHHLCA rabbits) by selective breeding. In this study, we examined the relation of atherosclerotic plaques to the onset of myocardial infarction. We examined myocardial lesions of 378 WHHL rabbits born between 1992 and 2000, and atherosclerosis lesions of 93 WHHLCA and 82 WHHLMI rabbits. The aortic lesions were evaluated as percent surface lesion area. The coronary lesions were evaluated as cross sectional narrowing using sections prepared at 500 or 1,000 μm intervals. Serum lipid levels were assayed with enzymatic methods. The cumulative incidence of fatal myocardial infarction between 11 and 35 months old was 90% in WHHLMI rabbits and 21% in WHHLCA rabbits, respectively. Selective breeding increased the serum cholesterol levels by about 200 mg/dl despite there being no changes in triglyceride levels. Aortic and coronary atherosclerosis progressed markedly in WHHLMI rabbits compared to WHHLCA rabbits. Especially, WHHLMI rabbits over 15 months old showed more than 90% cross sectional narrowing of the left circumflex arteries, main stem of the left coronary artery, and the origin portion of the right coronary artery. In addition, there were no gender differences in atherosclerotic lesions of both aortas and coronary arteries. In conclusion, the present study showed that marked progression of coronary atherosclerosis was probably associated with spontaneous development of myocardial infarction in WHHLMI rabbits.

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The purpose of the present study was to clarify the differences in the alterations of cellular activities of osteoblasts and osteoclasts, mineralization, and bone mass in cortical and cancellous bones of young growing rats with mild calcium deficiency. Twenty female Sprague-Dawley rats, 6 weeks of age, were randomized by the stratified method into two groups with 10 rats in each group: 0.5% (normal) calcium diet group and 0.1% (low) calcium diet group. After 10 weeks of feeding, bone histomorphometric analysis was performed on cancellous bone of the proximal tibia as well as cortical bone of the tibial shaft. Calcium deficiency increased eroded surface (ES/bone surface [BS]) and the number of osteoclast (N.Oc/BS) with an increase in osteoblast surface (ObS/BS), but decreased bone formation rate (BFR/BS) in cancellous bone. However, cancellous bone volume was preserved, while cortical bone area was decreased as a result of decreased periosteal bone gain and enlargement of the marrow cavity. These results suggest that short-term mild calcium deficiency in young growing female rats increased bone resorption by increasing osteoclastic recruitment, and suppressed mineralization followed by increased osteoblastic recruitment in cancellous bone, but cancellous bone loss was counteracted through redistribution of calcium from cortical bone to cancellous bone.

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We have developed a new method for separating mouse eggs from other cells, such as cumulus cells, using centrifugation with Percoll. Solutions of 45, 22.5, 11.3, and 5.6% Percoll were tested. With the 22.5% solution, 99% of whole eggs obtained by in vitro fertilization were collected from the upper part of the Percoll solution, and 98% of 2-cell embryos collected from these eggs developed to the blastocyst stage. Offspring were obtained after transfer of collected embryos to female mice. The greatest advantage of this method is that undamaged eggs are separated from other cells in one simple operation, regardless of the number of eggs.

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The effects of two sugar alcohols on feed utilization, digesta retention, gut fermentation and serum lipid profiles were compared in normal and cecectomized rats to examine the possibility of the cecectomized rat as an experimental animal with relevance to humans. Semi-purified diets containing no sugar alcohol, 7% sorbitol or 7% lactitol were fed to normal and cecectomized rats for 16 days. The digestibility of the crude fat and the compositions of the carcass dry matter and crude fat were significantly decreased by feeding sugar alcohols in both groups, but the effects were relatively higher in the cecectomized rats than in the normal rats. Diarrhea, faster transit times and shorter retention times of digesta were noted in the cecectomized rats fed sugar alcohols, while the inverse results were observed in the normal rats fed similar diets. The concentration of cecal organic acids was increased in the normal rats, whereas the concentration of colonic organic acids was decreased in the cecectomized rats fed sugar alcohols, compared with their corresponding control groups. The concentration of serum total cholesterol was decreased in both the normal and cecectomized rats fed diets containing sugar alcohols. The tendencies for diarrhea, faster digesta transit and reduced body fat induced by the fermentable materials in the cecectomized rat have good relevance to the parallel effects of fermentable materials in humans, suggesting the possibility of using the cecectomized rat as a model to study some of the physiological effects of sugar alcohols in humans.

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The aim of this study was to examine the effects of psychological stress on autonomic control of the heart in rats. For this purpose, we evoked anxiety-like or fear-like states in rats by means of classical conditioning and examined changes in autonomic nervous activity using an implanted telemetry system and power spectral analysis of heart rate variability. Anxiety-like states resulted in a significant increase in heart rate (HR), low frequency (LF) power, and LF/HF ratio, with no change in high frequency (HF) power. Fear-like states resulted in a significant increase in HR and a significant decrease in HF power with no significant change in both LF power and LF/HF ratio, although LF/HF ratio increased slightly. These results suggest that autonomic balance becomes predominant in sympathetic nervous activity in both anxiety-like and fear-like states. These changes in rats correspond to changes which are relevant to cardiovascular diseases in humans under many kinds of psychological stress. Therefore, the experimental design of this study is a useful experimental model for investigating the effects of psychological stress on autonomic control of the heart in humans.

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TF is a mutant rat strain showing male pseudohermaphroditism controlled by an autosomal single recessive gene (mp). The affected rats show lack of Leydig cells and androgen deficiency. In this study, we performed linkage analysis using F₂ progeny of crosses between TF and BN strains to determine the chromosomal localization of the mp locus. The mp locus was mapped in a 4 cM region of the distal region of rat chromosome 7 between D7Rat3 and D7Rat115 or D7Rat94. Comparison of the linkage map with corresponding regions of the published rat genome sequence revealed several candidate genes for the mp mutation, including the Dhh, Tegt, Gdp3, and Amhr2 genes.

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Retrograde axonal transport of latex nanospheres offers a means of delivering chemical agents to a targeted region of the central nervous system (CNS). In this study we performed microinjections of latex nanospheres into the cerebral cortex of cynomolgus monkeys and observed successful retrograde labeling of neurons in the contralateral region. Our data indicate the successful use of this delivery system, reported in studies using other animals, may also be achievable with primates as well.

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The transgenic Tsukuba hypertensive mouse (THM), which expresses the human renin and angiotensinogen genes, develops hypertension secondary to increased renin-angiotensin system activity. The aim of the present study was to assess expression of the renin, cyclooxygenase-2 (COX-2), and neuronal nitric oxide synthase (nNOS) proteins in THM kidneys by immunohistochemical stainings. Renin expression was decreased in the THM kidneys when compared to kidneys from heterozygotes or control mice. Although no differences were observed in nNOS expression, overexpression of the COX-2 protein was observed in the macula densa cells in THM kidneys.

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We compared the toxicokinetics of bisphenol A (BPA) among three animal species: rats, cynomolgus monkeys and chimpanzees. Rats and monkeys were administered BPA orally or subcutaneously at 10 or 100 mg/kg body weight, while chimpanzees were administered only 10 mg/kg of BPA. BPA in serum was measured by ELISA. In oral administration of BPA at 10 mg/kg, both C_max and AUC were rats < chimpanzee < monkeys. In oral administration of BPA at 100 mg/kg, both C_max and AUC were rats < monkeys. Subcutaneous BPA administrations also revealed similar results, although the values of toxicokinetic parameters in subcutaneous administration were higher than those in oral administration. These results suggest that orally or subcutaneously administered BPA in primates is more easily absorbed than that in rats. We conclude that there are considerable differences in distribution, metabolism, and excretion of BPA between rodents and primates.

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We investigated whether refined follicle stimulating hormone (FSH) with only a little contaminating LH can promote the responsiveness of rabbits to multiple-ovulation treatment. One group of female rabbits was stimulated with refined porcine FSH (pFSH), an FSH source with low LH activity, and another group was treated with pFSH. The mean number of eggs recovered from donors stimulated with refined pFSH (27 ± 3) was significantly greater (P<0.05) than that with pFSH (20 ± 2). Furthermore, the mean number of remaining follicles of donors stimulated with refined pFSH (19 ± 4) was significantly greater (P<0.05) than that with pFSH (12 ± 1). To decrease the number of remaining follicles in donors treated with refined pFSH, the dose of human chorionic gonadotropin (hCG) was increased from 75 to 150. However, there were no differences in the numbers of eggs and remaining follicles. The results of the present study suggest that refined pFSH with little contaminating LH promotes the responsiveness of rabbits to multiple-ovulation treatment compared with pFSH.

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