Mitochondrial Phylogeography and Population History of the Large Japanese Wood Mouse (Apodemus speciosus) on Sado Island, Japan

A phylogeographic study of the large Japanese wood mouse, Apodemus speciosus, on Sado Island, Japan, was performed based on sequences of the mitochondrial cytochrome b gene (1,140 bp). Our previous study covered the entire species range and suggested that the mice on Sado Island are monophyletic, exhibiting two well diverged lineages throughout the island. The present data also supported two lineages (the average number of nucleotide difference was 11.4), showing a weak phylogeographic structure. Given the high sequence divergence observed, we assumed historically subdivided populations within the island. Bayesian coalescent analysis supported a dual-population model rather than that of one large population. The times to most recent common ancestor of all sequences were 293,000 years ago [ka; 95% highest probability density (HPD) 85-634 ka] and 292 ka (HPD 102-605 ka) for the one- and dual-population models, respectively. These results suggest that the populations have undergone repeated separations and reconnections, rather than being subdivided completely through time. Our results are in accordance with other paleogeographic and phylogeographic evidence from the island. The present study highlighted a unique system of producing and maintaining genetic diversity and suggested prehistoric colonization of the A. speciosus population on Sado Island, thus supporting the ancient origin of the mammalian fauna of Sado Island

Genes for Difference in Eosinophilic Phenotype between MES and BN.MES-Cyba(mes) Rats Are on Chromosomes 9, 5, and 1

The Matsumoto Eosinophilia Shinshu (MES) rat strain develops hereditary blood eosinophilia due to the mutant Cyba(mes) gene. In contrast, BN.MES-Cyba(mes) congenic rats, in which the mutant Cyba(mes) gene introduced into the background of the BN strain, have a normal blood eosinophil level despite showing robust proliferation of eosinophils in the bone marrow. However, the congenic rats manifest focal necrosis with eosinophilic infiltration in the liver, a phenotype rarely observed in the original MES rat strain. To elucidate the genetic basis for the strain differences, (MES x BN.MES-Cyba(mes))F(2) rats were bred, and genetic analyses of phenotypes for eosinophilia were performed. Blood and bone marrow eosinophil levels in the F(2) rats showed broad distributions, suggesting that the traits were under the influence of multiple genes. Genetic association studies revealed that BN-derived marker loci on chromosomes 9 and 5 were responsible for the increase in eosinophil level in the bone marrow, decrease in blood eosinophil level, and the induction of focal necrosis with eosinophilic infiltration in the liver. The BN-derived allele of the marker gene on chromosome 1 was responsible for the decrease of both bone marrow and blood eosinophil levels. These data suggest the existence of genes characterizing/distinguishing the eosinophilic phenotypes of MES and BN.MES-Cyba(mes) on these chromosomes, and form the basis for positional cloning studies of the genes. These studies will advance the understanding of the mechanisms involved in eosinophil mobilization from the bone marrow and recruitment to the organs.ArticleEXPERIMENTAL ANIMALS. 60(2):151-160 (2011)journal articl

Suppressive Effect on Food Intake of a Potato Extract (Potein®) Involving Cholecystokinin Release in Rats

We have recently reported that oral gavage of a potato extract (Potein®) suppressed the food intake in rats. The satiating effect of the potato extract was compared in the present study to other protein sources, and the involvement of endogenous cholecystokinin (CCK) secretion was examined. Food consumption was measured in 18-h fasted rats after oral gavage of the potato extract or other protein sources. The CCK-releasing activity of the potato extract was then examined in anesthetized rats with a portal cannula. Oral gavage of the potato extract reduced the food intake in the rats, the effect being greater than with casein and a soybean β-conglycinin hydrolysate. The suppressive effect on appetite of the potato extract was attenuated by treating with a CCK-receptor antagonist (devazepide). The portal CCK concentration was increased after a duodenal administration of the potato extract to anesthetized rats. These results indicate that the potato extract suppressed the food intake in rats through CCK secretion

BN.MES-Cyba(mes) Congenic Rats Manifest Focal Necrosis with Eosinophilic Infiltration in the Liver without Blood Eosinophilia

The Matsumoto Eosinophilia Shinshu (MES) rat strain develops hereditary blood eosinophilia and eosinophil-related inflammatory lesions in organs due to the mutant Cyba(mes) gene. We hypothesized that a new eosinophilia model with a different phenotype could be established by changing the genetic background of rats. We bred and characterized a congenic strain, in which the mutant Cybames gene was introduced into the background of a BN strain (BN.MES-Cyba(mes)). The congenic rats showed robust proliferation of eosinophils in the bone marrow. Nonetheless, blood eosinophil levels of the rats remained within the normal range. In addition, the rats manifested focal necrosis with eosinophilic infiltration in the liver, a phenotype rarely observed in the original MES rat strain. These results imply the presence of genetic polymorphisms between MES and BN strains which modulate the mobilization of eosinophils to the peripheral circulation and organs. The newly established BN.MES-Cyba(mes) congenic rat strain, together with the original MES strain, will provide useful models for elucidating the molecular genetic mechanisms involved in the development and trafficking of eosinophils.ArticleEXPERIMENTAL ANIMALS. 59(4):469-478 (2010)journal articl

Genes for Difference in Eosinophilic Phenotype between MES and BN.MES-Cybames Rats Are on Chromosomes 9, 5, and 1

The Matsumoto Eosinophilia Shinshu (MES) rat strain develops hereditary blood eosinophilia due to the mutant Cyba(mes) gene. In contrast, BN.MES-Cyba(mes) congenic rats, in which the mutant Cyba(mes) gene introduced into the background of the BN strain, have a normal blood eosinophil level despite showing robust proliferation of eosinophils in the bone marrow. However, the congenic rats manifest focal necrosis with eosinophilic infiltration in the liver, a phenotype rarely observed in the original MES rat strain. To elucidate the genetic basis for the strain differences, (MES x BN.MES-Cyba(mes))F(2) rats were bred, and genetic analyses of phenotypes for eosinophilia were performed. Blood and bone marrow eosinophil levels in the F(2) rats showed broad distributions, suggesting that the traits were under the influence of multiple genes. Genetic association studies revealed that BN-derived marker loci on chromosomes 9 and 5 were responsible for the increase in eosinophil level in the bone marrow, decrease in blood eosinophil level, and the induction of focal necrosis with eosinophilic infiltration in the liver. The BN-derived allele of the marker gene on chromosome 1 was responsible for the decrease of both bone marrow and blood eosinophil levels. These data suggest the existence of genes characterizing/distinguishing the eosinophilic phenotypes of MES and BN.MES-Cyba(mes) on these chromosomes, and form the basis for positional cloning studies of the genes. These studies will advance the understanding of the mechanisms involved in eosinophil mobilization from the bone marrow and recruitment to the organs.ArticleEXPERIMENTAL ANIMALS. 60(2):151-160 (2011)journal articl

BN.MES-Cybames Congenic Rats Manifest Focal Necrosis with Eosinophilic Infiltration in the Liver without Blood Eosinophilia

The Matsumoto Eosinophilia Shinshu (MES) rat strain develops hereditary blood eosinophilia and eosinophil-related inflammatory lesions in organs due to the mutant Cyba(mes) gene. We hypothesized that a new eosinophilia model with a different phenotype could be established by changing the genetic background of rats. We bred and characterized a congenic strain, in which the mutant Cybames gene was introduced into the background of a BN strain (BN.MES-Cyba(mes)). The congenic rats showed robust proliferation of eosinophils in the bone marrow. Nonetheless, blood eosinophil levels of the rats remained within the normal range. In addition, the rats manifested focal necrosis with eosinophilic infiltration in the liver, a phenotype rarely observed in the original MES rat strain. These results imply the presence of genetic polymorphisms between MES and BN strains which modulate the mobilization of eosinophils to the peripheral circulation and organs. The newly established BN.MES-Cyba(mes) congenic rat strain, together with the original MES strain, will provide useful models for elucidating the molecular genetic mechanisms involved in the development and trafficking of eosinophils.ArticleEXPERIMENTAL ANIMALS. 59(4):469-478 (2010)journal articl