Hypoxia inducible factor 1α expression and effects of its inhibitors in canine lymphoma

Hypoxic conditions in various cancers are believed to relate with their malignancy, and hypoxia inducible factor-1α (HIF-1α) has been shown to be a major regulator of the response to low oxygen. In this study, we examined HIF-1α expression in canine lymphoma using cell lines and clinical samples and found that these cells expressed HIF-1α. Moreover, the HIF-1α inhibitors, echinomycin, YC-1 and 2-methoxyestradiol, suppressed the proliferation of canine lymphoma cell lines. In a xenograft model using NOD/scid mice, echinomycin treatment resulted in a dose-dependent regression of the tumor. Our results suggest that HIF-1α contributes to the proliferation and/or survival of canine lymphoma cells. Therefore, HIF-1α inhibitors may be potential agents to treat canine lymphoma.     

Bone morphological analyses in Spontaneously Diabetic Torii (SDT) fatty rats

The Spontaneously Diabetic Torii (SDT) fatty rat, a model for obese type 2 diabetes, shows bone quantitative abnormalities, namely low bone mineral density (BMD). The objective of this study was to evaluate bone morphological changes, in particular identifying the bone qualitative abnormalities, in the SDT fatty rat. Male SDT fatty rats showed increases in total trabecular area and trabecular number and decreases in trabecular thickness in cancellous bones of the proximal tibia, indicating trabecular miniaturization. The SDT fatty rat is useful for investigation of pathophysiological changes in bone quality in diabetic osteoporosis.     

Diversity in the carotenoid profiles and the expression of genes related to carotenoid accumulation among citrus genotypes

Carotenoids are not only important to the plants themselves but also are beneficial to human health. Since citrus fruit is a good source of carotenoids for the human diet, it is important to study carotenoid profiles and the accumulation mechanism in citrus fruit. Thus, in the present paper, we describe the diversity in the carotenoid profiles of fruit among citrus genotypes. In regard to carotenoids, such as β-cryptoxanthin, violaxanthin, lycopene, and β-citraurin, the relationship between the carotenoid profile and the expression of carotenoid-biosynthetic genes is discussed. Finally, recent results of quantitative trait locus (QTL) analyses of carotenoid contents and expression levels of carotenoid-biosynthetic genes in citrus fruit are shown.     

Molecular and genealogical analysis of grain dormancy in Japanese wheat varieties,with specific focus on MOTHER OF FT AND TFL1 on chromosome 3A

In the wheat (Triticum aestivum L.) cultivar ‘Zenkoujikomugi’, a single nucleotide polymorphism (SNP) in the promoter of MOTHER OF FT AND TFL1 on chromosome 3A (MFT-3A) causes an increase in the level of gene expression, resulting in strong grain dormancy. We used a DNA marker to detect the ‘Zenkoujikomugi’-type (Zen-type) SNP and examined the genotype of MFT-3A in Japanese wheat varieties, and we found that 169 of 324 varieties carry the Zen-type SNP. In Japanese commercial varieties, the frequency of the Zen-type SNP was remarkably high in the southern part of Japan, but low in the northern part. To examine the relationship between MFT-3A genotype and grain dormancy, we performed a germination assay in three wheat-growing seasons. On average, the varieties carrying the Zen-type SNP showed stronger grain dormancy than the varieties carrying the non-Zen-type SNP. Among commercial cultivars, ‘Iwainodaichi’ (Kyushu), ‘Junreikomugi’ (Kinki-Chugoku-Shikoku), ‘Kinuhime’ (Kanto-Tokai), ‘Nebarigoshi’ (Tohoku-Hokuriku), and ‘Kitamoe’ (Hokkaido) showed the strongest grain dormancy in each geographical group, and all these varieties, except for ‘Kitamoe’, were found to carry the Zen-type SNP. In recent years, the number of varieties carrying the Zen-type SNP has increased in the Tohoku-Hokuriku region, but not in the Hokkaido region.     

Experimental studies on sulfur dioxide injuries in higher plants

Photosynthesis is reversibly inhibited by exposing plants to SO₂. The formation of α-hydroxy sulfonate in the exposed plants is suggested as one of the effects, because this compound inhibits glycolic oxidase which is necessary in the glycolic acid pathway. The suppression of the glycolic acid path should affect various aspects of metabolism in plants, particularly the reduction of the biosynthesis of glycine and serine. In this paper, the biosynthesis of these amino acids in plants exposed to SO₂ was investigated to estimate the significance of the formation of α-hydroxy sulfonate in the plants. The results show that photosynthetic formation of serine was reduced in the exposed plants, and that α-hydroxy sulfonate was formed.     

Influences of indigenous phototrophs on methane emissions from a straw-amended paddy soil

A pot experiment was conducted to investigate the influences of indigenous phototrophs on methane (CH₄) emissions from a paddy soil where rice straw was incorporated or was surface-applied. During the cultivation, half of the pots were covered with aluminum foil, except for the minimum space for rice plants, to prevent ambient light reaching the floodwater or the soil surface. Growth of oxygen-producing phototrophs was hardly observed in the unilluminated plots, whereas intensive growth of algae, duckweed and hydrophytes was found in the illuminated ones. Plant growth was not affected by the different treatments. Seasonal changes in CH₄ emission determined by a closed chamber method indicated that illumination had no or only minor effects on CH₄ emissions when rice straw was incorporated or was not applied, but significantly reduced CH₄ emissions when rice straw was surface-applied. Methanogenesis occurring in the soil-floodwater interface was further investigated in two lab-scale model experiments measuring methanogenic activity. As a result, more activated methanogenesis was found in the surface-applied rice straw and the soil around the straw compared with the soil incubated without rice straw. The magnitude of the methanogenic activity in the rice straw incubated under illuminated conditions was significantly lower than that incubated in the dark. Consequently, this study demonstrates that methanogenesis in paddy soil occurs even in the soil-floodwater interface if plant residues like rice straw exist, and such methanogenesis is likely to be suppressed by growth of indigenous phototrophs under illumination.     

Effects of Inoculation of Phototrophic Purple Bacteria on Grain Yield of Rice and Nitrogenase Activity of Paddy Soil in a Pot Experiment

Phototrophic purple bacteria (PPB) are one group of dinitrogen (N₂)-fixing bacteria often found in the anoxic and photic zone of paddy soil. In the present study, the effects of inoculation of PPB on grain yield of rice and changes in their populations and nitrogenase activity were investigated with and without surface application of rice straw in a pot experiment. As an inoculant, Rhodopseudomonas palustris strain KN122 isolated from a paddy soil was selected, and the cell suspension was inoculated into the floodwater once or three times during the cultivation. As a result, the inoculation of PPB increased the grain yield of rice. Compared to the control, the grain yield was 9% higher in the inoculated plot without rice straw application. The treatment was more effective in combination with rice straw application. In the plots where PPB were inoculated with rice straw, grain yields were 21% (single inoculation) and 29% (triple inoculation) higher. Populations of PPB in the plots without rice straw application significantly increased by the inoculation, unlike those in the plots with rice straw application, except for the bulk soil. Phototrophic and heterotrophic nitrogenase activities (acetylene-reducing activity) associated with the soils or residues of the rice straw were not affected by PPB inoculation throughout the experiment. This indicates that the inoculation of PPB into floodwater may not be effective for enhancing N₂ fixation in paddy soils and that the beneficial effect of PPB inoculation on the grain yield of rice may be due to unidentified functions of PPB other than biological N₂ fixation.     

Promotion of intramuscular fat accumulation in porcine muscle by nutritional regulation

Recently, pork with marbling has received attention as good quality pork and scientists are required to develop methods to produce pork with reasonable amounts of intramuscular fat (IMF). The aim of this review is to describe studies relevant to promotion of IMF accumulation in porcine muscle by nutritional regulation. The main focus is on effect of dietary lysine levels. First, we found dietary low lysine up‐regulated glucose transporter protein 4 messenger (m)RNA expression in Longissimus dorsi (L. dorsi) and Rhomboideus muscles. In addition, the proportion of oxidative fiber of both muscles was also enhanced by dietary low lysine. Because it has been observed that higher oxidative capacity is associated with higher IMF content, we hypothesized that dietary low lysine would promote IMF accumulation. Further, higher mRNA abundance of peroxisome proliferator‐activated receptor γ, a master regulator of adipogenesis, in both muscles induced by dietary low lysine, supported this hypothesis. Indeed, IMF content of L. dorsi muscle of finishing pigs given a low lysine diet for 2 months until reaching the market weight was twice that of pigs given a control diet. Possible underlying mechanisms of IMF accumulation in porcine muscle and future perspectives are also discussed in this review.