Selenoneine suppresses melanin synthesis by inhibiting tyrosinase in murine B16 melanoma cells and 3D-cultured human melanocytes

Fisheries Science - The novel organic selenium compound, selenoneine, is found in the blood of tuna and has metal-binding activity. In this report, selenoneine displays tyrosinase inhibitory...     

DNA methylation profile: a composer-, conductor-, and player-orchestrated Mammalian genome consisting of genes and transposable genetic elements

Epigenetic systems play crucial roles in the differentiation of a mammalian fertilized egg into hundreds of cell types exhibiting distinct phenotypes, using a set of DNA molecules comprising about 3 billion nucleotides. Genome-wide analyses of epigenetic marks have revealed the remarkably well-established and well-maintained structure of the epigenome, consisting of DNA methylation and histone modifications that vary their state in a tissue type- and developmental stage-specific manner at numerous genomic loci. DNA methylation profiles comprising numerous tissue-dependent and differentially methylated regions (T-DMRs), found at such loci, are unique to every type of cell and tissue, and illuminate molecular networks that represent their phenotypes. T-DMRs are located in not only genic but also nongenic regions-including transposable genetic elements, such as short interspersed transposable element. Epigenetic studies indicate that the molecules that perform these modifications directly, such as DNA methyltransferases and eukaryotic histone methyltransferases, or indirectly, such as CpG-binding protein and noncoding RNAs-and combinations of these-contribute to the DNA methylation profile. It remains to be addressed how these molecules precisely find their target genomic loci.     

Contribution of understory vegetation to minimizing nitrate leaching in a Japanese cedar plantation

Understory vegetation may affect nitrate (NO₃ ⁻) leaching, even in coniferous forests. Our objective was to estimate the contribution of understory vegetation to nutrient cycling, especially nitrogen, in a Japanese cedar (Cryptomeria japonica) stand. We therefore cut down and removed understory vegetation in one plot of the stand (the cutting plot) to compare nutrient budgets in the cutting plot with those in a control plot in which understory vegetation was allowed to grow. We also examined neutralization of the acid produced due to an increase in NO₃ ⁻ leaching. A monitoring study on precipitation and soil-percolated water was carried out in both plots. When the understory vegetation was cut down, NO₃ ⁻ flux at a soil depth of 10 cm increased remarkably in summer, with values significantly higher than those in the control plot. This resulted in an increase in proton load associated with N transformation ([H⁺]load). The increase in [H⁺]load enhanced mobilization of Ca²⁺, Mg²⁺, and SiO₂ ([SiO₂]mob). In addition, the correlations between [SiO₂]mob and mobilization of each base cation were distinct in the cutting plot. These results indicated that the acids produced because of N transformation were buffered not only by ion exchange but also by chemical weathering. The contribution of understory vegetation to minimizing NO₃ ⁻ leaching suggested that understory vegetation might reduce the risk of N saturation because of chronic atmospheric N inputs.     

Cesium radioactivity in peripheral blood is linearly correlated to that in skeletal muscle: Analyses of cattle within the evacuation zone of the Fukushima Daiichi Nuclear Power Plant

The accident at the Fukushima Daiichi Nuclear Power Plant (FNPP) released a large amount of radioactive substances into the environment. Furthermore, beef contaminated with radioactive cesium above the 500 Bq/kg safety standard was circulated in the food chain in 2011. Japanese consumers remain concerned about the safety of radioactively contaminated food. In our previous study, we detected a linear correlation between radioactive cesium (¹³⁷Cs) activity in blood and muscle around 500 to 2500 Bq/kg in cattle. However, it was unclear whether the correlation was maintained at a lower radioactivity close to the current safety standard of 100 Bq/kg. In this study, we evaluated 17 cattle in the FNPP evacuation zone that had a ¹³⁷Cs blood level less than 10 Bq/kg. The results showed a linear correlation between blood ¹³⁷Cs and muscle ¹³⁷Cs (Y = 28.0X, R² = 0.590) at low radioactivity concentration, indicating that cesium radioactivity in the muscle can be estimated from blood radioactivity. This technique would be useful in detecting high‐risk cattle before they enter the market, and will contribute to food safety.     

Intraperitoneal administration of synthetic microRNA-214 elicits tumor suppression in an intraperitoneal dissemination mouse model of canine hemangiosarcoma

Canine hemangiosarcoma (HSA) has an extremely poor prognosis, making it necessary to develop new systemic treatment methods. MicroRNA-214 (miR-214) is one of many microRNAs (miRNA) that can induce apoptosis in HSA cell lines. Synthetic miR-214 (miR-214/5AE), which showed higher cytotoxicity and greater nuclease resistance than mature miR-214, has been developed for clinical application. In this study, we evaluated the effects of miR-214/5AE on stage 2 HSA in a mouse model. Mice intraperitoneally administered with miR-214/5AE (5AE group) had significantly fewer intraperitoneal dissemination tumor foci (median number: 72.5 vs. 237.5; p?<?0.05) and a lower median foci weight (0.26 g vs. 0.61 g; p?<?0.05). Mice in the 5AE group had increased expression of p53 and cleaved caspase-3, and a significantly lower proportion of Ki-67-positive cells, than those in the non-specific miR group. Notably, no significant side effects were observed. These results indicate that intraperitoneal administration of miR-214/5AE exhibits antitumor effects in an intraperitoneal dissemination mouse model of HSA by inducing apoptosis and suppressing cell proliferation. These results provide a basis for future studies on the antitumor effect of miR-214/5AE for HSA.

     

Impacts of climate change on rice market and production capacity in the Lower Mekong Basin

The supply of water is affected by climate changes. In addition, high economic growth in the lower Mekong River countries including two large rice exporters is expected to reduce the per capita consumption of rice as incomes grow. Consequently, the need exist to investigate changes in supply and demand using econometric models of rice markets in the countries, where water supplies are expected to change. The objective of this research is to clarify impacts of water supply changes on rice producers and consumers using supply and demand models of rice considering changes in the water supply to aid in producing agricultural policies and plans. The following two simulations were conducted in this assessment: (a) baseline and (b) CC_B2. The simulation of the baseline includes the assumption that the evapotranspiration (ET) of each province after 2000 is the average quantity of ET from 1995 to 1999. The simulation of the CC_B2 includes the assumptions that ET of each province after 2010 accords with the IPCC socioeconomic scenario B2. The simulation results suggest that climate change will depress wet season rice production in Cambodia and Mekong River Delta (MRD) region in Vietnam, and that of dry season rice in the MRD region in Vietnam and northeastern region (Isan) Thailand. The simulation results also indicate that climate change will increase farm prices of rice in Cambodia, Vietnam, and Thailand. The results suggest that climate changes will weigh on the livelihood of rice consumers, especially those of poor rural populations.     

Irradiation history of Itokawa regolith material deduced from noble gases in the Hayabusa samples

Noble gas isotopes were measured in three rocky grains from asteroid Itokawa to elucidate a history of irradiation from cosmic rays and solar wind on its surface. Large amounts of solar helium (He), neon (Ne), and argon (Ar) trapped in various depths in the grains were observed, which can be explained by multiple implantations of solar wind particles into the grains, combined with preferential He loss caused by frictional wear of space-weathered rims on the grains. Short residence time of less than 8 million years was implied for the grains by an estimate on cosmic-ray-produced (21)Ne. Our results suggest that Itokawa is continuously losing its surface materials into space at a rate of tens of centimeters per million years. The lifetime of Itokawa should be much shorter than the age of our solar system.     

Population size estimation of the pond smelt Hypomesus nipponensis in Lake Kasumigaura and Lake Kitaura,Japan

We estimated the population size of the pond smelt Hypomesus nipponensis at the beginning of the fishing season in Lake Kasumigaura and Lake Kitaura, Japan using two DeLury methods and cohort analysis. A growth curve was estimated on the basis of monthly standard length. The relationship between standard length and weight was utilized for calculating the mean weight on the survey day in a particular month. Total monthly catches in Lake Kasumigaura and Lake Kitaura were calculated using partial monthly pond smelt catch obtained from processing plants located near the lakes between July and December. The total monthly catch was calculated from the total monthly catch weight and the monthly mean weight. The number of boats operating each month, compiled by the Kasumigaura-Kitaura Fisheries Office of Ibaraki Prefecture, was also employed. The estimated initial population sizes were compared with the population level index (PLI) estimated from survey data before the start of the fishing season. No significant differences were detected among the initial population sizes estimated by DeLury method, cohort analysis and PLI. The estimates ranged from 7.4 million to 410 million in Lake Kasumigaura, and from 7.7 million to 44 million in Lake Kitaura.