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Search Results: 1 - 10 of 1160 matches for " Shoji Oda "
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Allelic Expression Changes in Medaka (Oryzias latipes) Hybrids between Inbred Strains Derived from Genetically Distant Populations
Yasuhiko Murata, Shoji Oda, Hiroshi Mitani
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0036875
Abstract: Variations in allele expressions between genetically distant populations are one of the most important factors which affects their morphological and physiological variations. These variations are caused by natural mutations accumulated in their habitats. It has been reported that allelic expression differences in the hybrids of genetically distant populations are different from parental strains. In that case, there is a possibility that allelic expression changes lead to novel phenotypes in hybrids. Based on genomic information of the genetically distant populations, quantification and comparison of allelic expression changes make importance of regulatory sequences (cis-acting factors) or upstream regulatory factors (trans-acting modulators) for these changes clearer. In this study, we focused on two Medaka inbred strains, Hd-rR and HNI, derived from genetically distant populations and their hybrids. They are highly polymorphic and we can utilize whole-genome information. To analyze allelic expression changes, we established a method to quantify and compare allele-specific expressions of 11 genes between the parental strains and their reciprocal hybrids. In intestines of reciprocal hybrids, allelic expression was either similar or different in comparison with the parental strains. Total expressions in Hd-rR and HNI were tissue-dependent in the case of HPRT1, with high up-regulation of Hd-rR allele expression in liver. The proportion of genes with differential allelic expression in Medaka hybrids seems to be the same as that in other animals, despite the high SNP rate in the genomes of the two inbred strains. It is suggested that each tissue of the strain difference in trans-acting modulators is more important than polymorphisms in cis-regulatory sequences in producing the allelic expression changes in reciprocal hybrids.
Dual control by a single gene of secondary sexual characters and mating preferences in medaka
Shoji Fukamachi, Masato Kinoshita, Kouichi Aizawa, Shoji Oda, Axel Meyer, Hiroshi Mitani
BMC Biology , 2009, DOI: 10.1186/1741-7007-7-64
Abstract: Through mate-choice experiences using several laboratory strains of various body colors, we successfully identified one medaka mutant (color interfere; ci) that is distinctly unattractive to reproductive partners. This unattractiveness seems to be due to reduced orange pigment cells (xanthophores) in the skin. The ci strain carries a mutation on the somatolactin alpha (SLa) gene, therefore we expected over-expression of SLa to make medaka hyper-attractive. Indeed, extremely strong mating preferences were detected in a choice between the ci and SLa-transgenic (Actb-SLa:GFP) medaka. Intriguingly, however, the strains showed opposite biases; that is, the mutant and transgenic medaka liked to mate with partners from their own strain, similar to becoming sexually isolated.This study spotlighted SLa as a novel mate-choice gene in fish. In addition, these results are the first demonstration of a single gene that can pleiotropically and harmoniously change both secondary sexual characters and mating preferences. Although theoretical models have long suggested joint evolution of linked genes on a chromosome, a mutation on a gene-regulatory region (that is, switching on/off of a single gene) might be sufficient to trigger two 'runaway' processes in different directions to promote (sympatric) speciation.Reproduction is one of the most important events in life. Animals of many species try a wide variety of measures, such as songs, dances, scents, ornaments, gifts, or electric fields [1], to attract mating partners for successful reproduction. Researchers have found that pre-mating sexual isolation by mate choice (that is, not by incompatibility of genital or other morphologies for copulation [2,3]) exists in various animal taxa including yeasts [4]. Teleost fish have also been used frequently as models for mate-choice experiments [5], and visual cues have often been shown to play an important (but not exclusive) role in mate attraction (for example, body colors, fin shapes, cou
Medaka: a promising model animal for comparative population genomics
Yoshifumi Matsumoto, Hiroki Oota, Yoichi Asaoka, Hiroshi Nishina, Koji Watanabe, Janusz M Bujnicki, Shoji Oda, Shoji Kawamura, Hiroshi Mitani
BMC Research Notes , 2009, DOI: 10.1186/1756-0500-2-88
Abstract: Using Oryzias species from 27 local populations, we conducted a simple screening of nonsynonymous SNPs for 11 genes with apparent orthology between medaka and humans. We found medaka SNPs for which the same sites in human orthologs are known to be highly differentiated among the HapMap populations. Importantly, some of these SNPs show signals of positive selection.These results indicate that medaka is a promising model system for comparative population genomics exploring the functional and adaptive significance of allelic differentiations.The accumulation of human genetic polymorphism data provided by sources such as the international HapMap project [1,2] has revealed a number of SNP sites with markedly different allele frequencies among human populations. Such data make systematic searches for disease-causing or drug-responsive genomic regions possible [3,4], and the accumulated SNP data can also provide compelling evidence of positive selection during human evolution [5,6]. An inevitable issue, however, is that mutagenesis and/or crossing-over experiments to elucidate functional differences between alleles at these polymorphic sites are practically impossible in humans. A vertebrate model animal with a broad geographic distribution and documented high genetic polymorphism could serve as a "natural library" of genetic variation in humans for orthologous genes that could be under similar selective pressures.The medaka (Oryzias latipes) is a notable candidate for such a model animal. This small freshwater fish is found in East Asia with closely related congeneric species broadly distributed throughout Southeast Asia, and it has a long history of use as an experimental animal since the early 20th century. A number of inbred medaka strains have been established, and transgenesis and mutagenesis protocols have been developed, suggesting that medaka has great potential for use in systematic genetic analyses [7-10]. Medaka genome sequences are also available [11]. The gre
A Reaction-Diffusion Algorithm for Segmentation of Three-Dimensional Sinusoidal Networks in Rats Fed a High-Fat and High-Cholesterol Diet: New Insights and Evaluation  [PDF]
Hiroto Shoji
Journal of Biosciences and Medicines (JBM) , 2018, DOI: 10.4236/jbm.2018.610004
Abstract: Microstructures in the liver are primarily composed of hepatocytes, hepatic blood, and biliary vessels. Because each hepatocyte comes in contact with both vessels, these vessels form three-dimensional (3D) periodic network patterns. Confocal microscope images are useful for observing 3D structures; however, it is necessary to explicitly describe the vessel structures using 3D images of sinusoidal endothelial cells. For this purpose, we propose a new approach for image segmentation based on the Turing reaction-diffusion model, in which temporal and spatial patterns are self-organized. Turing conditions provided reliable tools for describing the 3D structures. Moreover, using the proposed method, the sinusoidal patterns of rats fed a high-fat/high-cholesterol diet were examined; these rats exhibited pathological features similar to those of human patients with nonalcoholic steatohepatitis related to metabolic syndrome. The findings showed that the parameter in diffusion terms differed significantly among the experimental groups. This observation provided a heuristic argument for parameter selection leading to pattern recognition problems in diseased rats.
A Comparative Analysis of Glomerulus Development in the Pronephros of Medaka and Zebrafish
Koichiro Ichimura, Ekaterina Bubenshchikova, Rebecca Powell, Yayoi Fukuyo, Tomomi Nakamura, Uyen Tran, Shoji Oda, Minoru Tanaka, Oliver Wessely, Hidetake Kurihara, Tatsuo Sakai, Tomoko Obara
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045286
Abstract: The glomerulus of the vertebrate kidney links the vasculature to the excretory system and produces the primary urine. It is a component of every single nephron in the complex mammalian metanephros and also in the primitive pronephros of fish and amphibian larvae. This systematic work highlights the benefits of using teleost models to understand the pronephric glomerulus development. The morphological processes forming the pronephric glomerulus are astoundingly different between medaka and zebrafish. (1) The glomerular primordium of medaka - unlike the one of zebrafish - exhibits a C-shaped epithelial layer. (2) The C-shaped primordium contains a characteristic balloon-like capillary, which is subsequently divided into several smaller capillaries. (3) In zebrafish, the bilateral pair of pronephric glomeruli is fused at the midline to form a glomerulus, while in medaka the two parts remain unmerged due to the interposition of the interglomerular mesangium. (4) Throughout pronephric development the interglomerular mesangial cells exhibit numerous cytoplasmic granules, which are reminiscent of renin-producing (juxtaglomerular) cells in the mammalian afferent arterioles. Our systematic analysis of medaka and zebrafish demonstrates that in fish, the morphogenesis of the pronephric glomerulus is not stereotypical. These differences need be taken into account in future analyses of medaka mutants with glomerulus defects.
Effects of hot-water extract of Paecilomyces hepiali on hypertension parameters in Spontaneously Hypertensive Rats  [PDF]
Alfred Chioza, Shoji Ohga
Advances in Microbiology (AiM) , 2014, DOI: 10.4236/aim.2014.48048
Abstract:

In this study, effects of hot water extract of Paecilomyces hepiali mycelia on hypertension parameters in spontaneously hypertensive rats (SHR) were investigated. The tested parameters included blood pressure, blood and urine biochemical composition, renin and angiotensin II levels in the blood. Prior to these tests, the extract was examined for toxicity. The fungus was cultivated in a solid medium composed of 40 g brown rice, 0.32 g glucose, 0.65 g sucrose, 2 g peptone and 65 ml corn steep liquor. No abnormality or harmful effects were observed in the toxicity test. Administration of a continuous-dose, once daily, to SHR for 27 weeks (from 13 weeks of age) decreased the systolic blood pressure (SBP) significantly. Levels of blood urea nitrogen, β-lipoprotein lipid peroxides and low density lipoprotein were significantly lower in the treated groups when compared to the control group. Urinary protein was significantly reduced in the middle and high dose groups. In comparison with the control group (0 mg/kg/10ml/day), significantly higher values were obtained for total cholesterol in groups that were given middle (170 mg/kg/10ml/day) and high (250 mg/kg/10ml/day) dosages. In all dosages (low, middle and high) the values for triglyceride were significantly higher than value found in the control group. In terms of angiotensin II levels, the value in the control group was markedly higher than values in the other groups. The results suggest that oral administration of hot water extract of P. hepiali mycelia has ability to control hypertension in rats.

Cultivated Mushrooms in Malawi: A Look at the Present Situation  [PDF]
Alfred Chioza, Shoji Ohga
Advances in Microbiology (AiM) , 2014, DOI: 10.4236/aim.2014.41002
Abstract:

This paper presents the status of mushroom cultivation in Malawi. This is a developing country located in southeastern Africa between latitudes 9°25' South and 17°08' South and longitudes 33° East and 36°East. Almost all the mushroom cultivators in the country are growing Pleurotus ostreatus. This species is most preferred because of its easiness to cultivate using the low-cost cultivation method being practiced in the country. On average, the annual P. ostreatus production is estimated at 240 kg per grower. Mushroom cultivators are selling their produce at prices ranging from MK800 (USD2.04) to MK2000 (USD5.10) per kg. At present, there are four institutions that are producing spawn namely Bunda College (Lilongwe University of Agriculture and Natural resources), Bvumbwe Agricultural Research Station, Natural Resources College and the Biology Department at Chancellor College, University of Malawi. Currently, a total of about 1307 bottles (330 ml each) of P. ostreatus spawn are sold by these four spawn producers per month. Mushroom cultivation is not that popular in Malawi. This may be, partly, attributed to lack of know-how and awareness on the economic, nutritive and medicinal benefits of cultivated mushrooms. Some of the major supermarkets do sell Agaricus bisporus mushrooms which are imported from the Republic of South Africa. They also sell Pleurotus ostreatus

A Comparative Study on Chemical Composition and Pharmacological Effects of Paecilomyces hepiali and Wild Ophiocordyceps sinensis  [PDF]
Alfred Chioza, Shoji Ohga
Advances in Microbiology (AiM) , 2014, DOI: 10.4236/aim.2014.412093
Abstract: This study looked at comparison of chemical components and pharmacological activity between wild Ophiocordyceps sinensis and Paecilomyces hepiali. The chemical components investigated included amino acids, vitamins, dietary elements, protein, lipid, ash, carbohydrates, crude fibre, ergosterol and mannitol. Studies on pharmacological activity included anti-platelet aggregation, inhibitory effect on IL-8 gene expression, anti-mutagenic activity, skin whitening effect and impro- vement activity on human skin texture. The results show that P. hepiali has a larger total content of seven essential amino acids (leucine, lysine, methionine, phenylalanine, tryptophan, tyrosine and valine) than O. sinensis, 8580 mg/100g and 6180 mg/100g respectively. The total content of dietary elements analysed (potassium, magnesium, zinc, copper, manganese and selenium) was also higher in P. hepiali (3135 mg/100g) than that in O. sinensis (2445 mg/100g). The total content of four vitamins (B1, B2, B6 and E) was almost equal for both fungi. Paecilomyces hepiali had more content of protein, lipid, ash, carbohydrate, ergosterol and mannitol than O. sinensis. However, the contents of lipid and ash were not significantly different between
Formulation of a Preconditioned Algorithm for the Conjugate Gradient Squared Method in Accordance with Its Logical Structure  [PDF]
Shoji Itoh, Masaaki Sugihara
Applied Mathematics (AM) , 2015, DOI: 10.4236/am.2015.68131
Abstract: In this paper, we propose an improved preconditioned algorithm for the conjugate gradient squared method (improved PCGS) for the solution of linear equations. Further, the logical structures underlying the formation of this preconditioned algorithm are demonstrated via a number of theorems. This improved PCGS algorithm retains some mathematical properties that are associated with the CGS derivation from the bi-conjugate gradient method under a non-preconditioned system. A series of numerical comparisons with the conventional PCGS illustrate the enhanced effectiveness of our improved scheme with a variety of preconditioners. This logical structure underlying the formation of the improved PCGS brings a spillover effect from various bi-Lanczos-type algorithms with minimal residual operations, because these algorithms were constructed by adopting the idea behind the derivation of CGS. These bi-Lanczos-type algorithms are very important because they are often adopted to solve the systems of linear equations that arise from large-scale numerical simulations.
Mycelial Growth of Paecilomyces hepiali in Various Agar Media and Yield of Fruit Bodies in Rice Based Media  [PDF]
Alfred Chioza, Shoji Ohga
Advances in Microbiology (AiM) , 2013, DOI: 10.4236/aim.2013.37071
Abstract: Growth of?Paecilomyces hepiali?in various agar media and yield of fruit bodies in rice based media were?studied. The best growth in agar media was obtained at 25?(61.86 mm colony diameter in 14 days). The initial agar media pH range?from?6 to 8 was found to be?the?most favourable for mycelial growth. This study found that agars made with powders of cereal grains alone do not support good mycelial growth of?P. hepiali. Addition of peptone improved mycelial growth significantly. The most favourable carbon sources were Mannose, Fructose and Glucose. Organic nitrogen sources were found to be?the?most preferred. The results demonstrated that brown rice is better than polished rice in yield of fruit bodies. Addition of peptone was found to be quite significant in enhancing yield of fruit bodies. Peptone, as a supplement, gave a better yield than addition of egg yolk, albumen and a mixture of the two. The medium with?40 g brown rice, 0.325 g glucose, 0.65 g sucrose, 2 g peptone and 65 ml corn steep liquor was found to be?the?most favourable and it yielded 19.3 g of fresh fruit bodies.
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