Theoretical studies on the methodological procedures of radiation breeding

If the expectation of the number of desirable mutants for equal size of X ₂-populations decreases with decreasing number of plants per X ₂-line, the one-plant-one-grain method (method C), the one-plant-two-grain method (method D), and the one-plant-three-grain method (method E), especially method C, would be disadvantageous in comparison with the improved ear-to-row method (method B) and the conventional ear-to-row method (method A).From theoretical considerations it can be shown that a probability of occurrence of an X ₂-line containing desirable mutant (p ₁) and a conditional probability of occurrence of such desirable mutant for each one of the plants in such an X ₂-line (p ₂) are not affected by the number of X ₂-lines (m), but by the number of plants per X ₂-line (n). Consequently, the expectation of the number of desirable mutants in an X ₂-population, E(I), can be given by E(I) = mp ₁(1– q ₂ n · n p ₂/(1 –q ₂ n) = mn p ₁ p ₂ where p ₁+q ₁=1 and p ₂+q ₂=1.Therefore, with respect to E(I), method A=B=C=D=E for equal size of X ₂-populations. However, method ABE>D>C for different sizes of X ₂-populations.Most of this work was carried out in the National Institute of Agricultural Sciences, Hiratsuka, Japan.     

Developmental changes of phyllochron in near-isogenic lines of rice (Oryza sativa L.) with different growth durations

The repeated elements called phytomers, which consist of leaf, node, internode and axillary bud, play an important role in the development of modular organization in plants. Rice has the striking feature that the rate of the phytomer production is closely synchronized with the rate of leaf emergence (phyllochron). We examined developmental changes of phyllochron by using 10 near-isogenic lines (NILs) showing diversified growth durations in rice. The NILs were established by backcrosses with a strain practically insensitive to photoperiod, and they consisted of early- or late-flowering NILs whose differences of growth duration were caused by the combinations of alleles at 6 loci. The developmental patterns of phyllochron were evaluated by means of a quartic polynomial, which fitted well in most cases. The results indicated that phyllochron greatly changed during development, especially in late-flowering NILs as well as the recurrent parents, although the fluctuation of phyllochron was not so marked in the early-flowering NILs. Thus, the developmental change of phyllochron was highly dependent upon the genotypes and/or growth duration; however, it was associated with neither floral initiation nor temperature, indicating that the change of phyllochron might reflect internal or physiological changes which occur during the life cycle of rice. This revised version was published online in July 2006 with corrections to the Cover Date.     

Study of the Water Solubility and Sorption on Particulate Matters of Phthalate in the Presence of Humic Acid Using 14C Labelled Di-(2-Ethylhexyl)Phthalate

Phthalate esters have become widespread contaminants in the aquatic environment, because of their extensive use as non-reactive plasticizers. There is, however, little accurate data on their solubility, transportation, and distribution in the aquatic environment. In this work, we have investigated the influence of humic acid on the water solubility of di-(2-ethylhexyl)phthalate (DEHP), one of the most frequently used phthalate esters in the laboratory studies for DEHP. We have also studied the solid–water distribution of DEHP in the presence of humic acid and particulate matter (activated carbon, ferrihydrite, and kaolinite) to simulate their distribution in a natural aquifer (ternary system). The results show that the water solubility of DEHP can be significantly increased by humic acid. The shape K _eq value, the binding constant of DEHP between water and humic acid at equilibrium, was obtained by fitting experimental data for each humic acid. The shape K _eq values in the ternary system apparently decreased in the order of ferrihydrite ≤ kaolinite ≈ octanol/water partition activated carbon systems. This result shows that the increase in the hydrophobicity of HA remaining in the solution will lead to the apparent increase of shape K _eq in the system since more hydrophilic solid sorbs relatively more hydrophilic HA molecule. The solid–water partition coefficient (shape K _W-P ) for DEHP in the environment estimated from this study is consistent with those reported based on the experiments for natural samples. Quantitative values obtained in this study, such as K'_ow, shape K _eq, and shape K _W-P , can be useful for estimating the behavior of DEHP.     

Antitumor activity of compounds isolated from leaves of Eriobotrya japonica

In a search for possible antitumor agents from natural sources, megastigmane glycosides and polyphenolic constituents isolated from the leaves of Eriobotrya japonica (Rosaceae) were found to inhibit the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced activation of Epstein-Barr virus early antigen in Raji cells. Roseoside and procyanidin B-2 were among the active compounds found in an in vitro assay; these compounds were further assessed for antitumor activity in vivo in a two-stage carcinogenesis assay on mouse skin. Roseoside significantly delayed carcinogenesis induced by peroxynitrite (initiator) and TPA (promoter), and its potency was comparable to that of a green tea polyphenol, (-)-epigallocatechin 3-O-gallate, in the same assay.     

Traces of human migrations in Helicobacter pylori populations

Helicobacter pylori, a chronic gastric pathogen of human beings, can be divided into seven populations and subpopulations with distinct geographical distributions. These modern populations derive their gene pools from ancestral populations that arose in Africa, Central Asia, and East Asia. Subsequent spread can be attributed to human migratory fluxes such as the prehistoric colonization of Polynesia and the Americas, the neolithic introduction of farming to Europe, the Bantu expansion within Africa, and the slave trade.     

Cartilage acidic protein-1B (LOTUS), an endogenous Nogo receptor antagonist for axon tract formation

Neural circuitry formation depends on the molecular control of axonal projection during development. By screening with fluorophore-assisted light inactivation in the developing mouse brain, we identified cartilage acidic protein-1B as a key molecule for lateral olfactory tract (LOT) formation and named it LOT usher substance (LOTUS). We further identified Nogo receptor-1 (NgR1) as a LOTUS-binding protein. NgR1 is a receptor of myelin-derived axon growth inhibitors, such as Nogo, which prevent neural regeneration in the adult. LOTUS suppressed Nogo-NgR1 binding and Nogo-induced growth cone collapse. A defasciculated LOT was present in lotus-deficient mice but not in mice lacking both lotus- and ngr1. These findings suggest that endogenous antagonism of NgR1 by LOTUS is crucial for normal LOT formation.     

Recovery of antioxidant activity from carnosol quinone: antioxidants obtained from a water-promoted conversion of carnosol quinone

Carnosol is one of the main antioxidants in sage and rosemary. Although carnosol quinone is the antioxidation product of carnosol and has a very weak antioxidant activity, its treatment in water-containing solvent restored its strong antioxidant activity. HPLC analysis of the water-stimulated recovery reaction of the antioxidant activity revealed that the strong activity was due to the reproduced carnosol. The analysis also showed that an almost equal amount of quinone derivatives of rosmanol (rosmanol quinone) was produced in the reaction along with the carnosol. The rosmanol was formed by the addition of 1 equiv of water and the following isomerization from carnosol quinone in the water-containing solvent. The formed rosmanol was also found to be oxidized by the remaining carnosol quinone to produce rosmanol quinone. At the same time, carnosol quinone was reduced to afford carnosol. This redox phenomenon is an important part of the mechanism for the recovery of the antioxidant activity from carnosol quinone under the water-containing conditions.     

Real-space observation of helical spin order

Helical spin order in magnetic materials has been investigated only in reciprocal space. We visualized the helical spin order and dynamics in a metal silicide in real space by means of Lorentz electron microscopy. The real space of the helical spin order proves to be much richer than that expected from the averaged structure; it exhibits a variety of magnetic defects similar to atomic dislocations in the crystal lattice. The application of magnetic fields allows us to directly observe the deformation processes of the helical spin order accompanied by nucleation, movement, and annihilation of the magnetic defects.     

Nationwide Cyprinid herpesvirus 3 contamination in natural rivers of Japan

Cyprinid herpesvirus 3 (CyHV-3) disease is a significant threat for common and koi carp cultivators and for freshwater ecosystems. To determine the prevalence of CyHV-3 in Japanese rivers, a nationwide survey of all national class-A rivers was undertaken in the Summer of 2008. The virus was concentrated from river water samples using the cation-coated filter method. CyHV-3 DNA was detected in 90 rivers, representing 90% of 103 successfully analysed rivers. More than 100,000 copies of CyHV-3 DNA per litre of sample were detected in four rivers, higher than that reported during the Yura River outbreak in 2007. For CyHV-3-positive rivers, the log CyHV-3 density was negatively correlated with the water temperature on the sampling date and positively correlated with the suspended solids and dissolved oxygen, which are annually averaged for each river. Our results demonstrate that virus detection using molecular biology techniques is a powerful tool for monitoring the presence of CyHV-3 in natural environments.