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Thermal vacancy behavior in B2-type FeAl was analyzed through thermal expansion, lattice parameter, and elastic modulus measurements. High-temperature X-ray diffractometry (HT-XRD) was conducted to determine the lattice parameter at elevated temperatures, and the electromagnetic acoustic resonance method was applied to investigate the temperature dependence of the elastic moduli in B2-type FeAl. Using a series of in situ high-temperature techniques such as HT-XRD and dilatometry, the thermal vacancy concentration at elevated temperatures was estimated from the divergence between the changes in the sample length and the lattice parameter with temperature, giving a vacancy formation enthalpy of ∼0.7 and 0.6 eV for Fe–40Al and Fe–43Al (at.%), respectively. The long-range order parameter was found to increase with temperature in a high-temperature range, indicating that the Fe-atom recovery process occurs in this temperature range. The in situ high-temperature measurements suggest that at elevated temperatures, thermal vacancies have no significant influence on the lattice parameter and elastic moduli of B2-type FeAl.

The cause and progression of Alzheimer's disease (AD) are poorly understood. Possible cognitive and behavioral consequences induced by low-dose radiation are important because humans are exposed to ionizing radiation from various sources. Early transcriptional response in murine brain to low-dose X-rays (100 mGy) has been reported, suggesting alterations of molecular networks and pathways associated with cognitive functions, advanced aging and AD. To investigate acute and late transcriptional, pathological and cognitive consequences of low-dose radiation, we applied an acute dose of 100-mGy total body irradiation (TBI) with X-rays to C57BL/6J Jms mice. We collected hippocampi and analyzed expression of 84 AD-related genes. Mouse learning ability and memory were assessed with the Morris water maze test. We performed in vivo PET scans with (11)C-PIB, a radiolabeled ligand for amyloid imaging, to detect fibrillary amyloid beta peptide (Aβ) accumulation, and examined characteristic AD pathologies with immunohistochemical staining of amyloid precursor protein (APP), Aβ, tau and phosphorylated tau (p-tau). mRNA studies showed significant downregulation of only two of 84 AD-related genes, Apbb1 and Lrp1, at 4 h after irradiation, and of only one gene, Il1α, at 1 year after irradiation. Spatial learning ability and memory were not significantly affected at 1 or 2 years after irradiation. No induction of amyloid fibrillogenesis or changes in APP, Aβ, tau, or p-tau expression was detected at 4 months or 2 years after irradiation. TBI induced early or late transcriptional alteration in only a few AD-related genes but did not significantly affect spatial learning, memory or AD-like pathological change in mice.

The hardening ability of some substitutional solute atoms was investigated and compared. It was theoretically shown that solute atoms have the effect to enhance the necking resistance during creep deformation at high temperatures and can improve the thermal fatigue property of the steels. Molybdenum which is known to have large solid solution hardening ability improves the thermal fatigue property by the solid solution hardening itself, plus the enhanced necking resistance through increase in strain rate exponent. Aluminum which is known to improve the oxidation resistance of the ferritic stainless steels has a sufficient solid solution hardening ability. Thermal fatigue life of the steel was improved by a small amount of Al addition. It can be ascribed to the solid solution hardening ability of Al plus the enhanced necking resistance through increase in strain rate exponent due to Al addition. The addition of the appropriate amount of Si would make the effect of solute Al more efficient by improving the oxidation resistance of the steel.

The cause and progression of Alzheimer's disease (AD) are poorly understood. Possible cognitive and behavioral consequences induced by low-dose radiation are important because humans are exposed to ionizing radiation from various sources. Early transcriptional response in murine brain to low-dose X-rays (100 mGy) has been reported, suggesting alterations of molecular networks and pathways associated with cognitive functions, advanced aging and AD. To investigate acute and late transcriptional, pathological and cognitive consequences of low-dose radiation, we applied an acute dose of 100-mGy total body irradiation (TBI) with X-rays to C57BL/6J Jms mice. We collected hippocampi and analyzed expression of 84 AD-related genes. Mouse learning ability and memory were assessed with the Morris water maze test. We performed in vivo PET scans with (11)C-PIB, a radiolabeled ligand for amyloid imaging, to detect fibrillary amyloid beta peptide (Aβ) accumulation, and examined characteristic AD pathologies with immunohistochemical staining of amyloid precursor protein (APP), Aβ, tau and phosphorylated tau (p-tau). mRNA studies showed significant downregulation of only two of 84 AD-related genes, Apbb1 and Lrp1, at 4 h after irradiation, and of only one gene, Il1α, at 1 year after irradiation. Spatial learning ability and memory were not significantly affected at 1 or 2 years after irradiation. No induction of amyloid fibrillogenesis or changes in APP, Aβ, tau, or p-tau expression was detected at 4 months or 2 years after irradiation. TBI induced early or late transcriptional alteration in only a few AD-related genes but did not significantly affect spatial learning, memory or AD-like pathological change in mice.

TiC was added to Mo-Si-B alloys using a conventional Ar arc-melting technique, and the phase equilibria, microstructure evolution, and high-temperature strength at 1673 K (1400 °C) were investigated. The primary phase changed to Mo solid solution (Moss), Mo5SiB2 (T2), or TiC depending on the composition. Following the primary phase solidification, a Moss + TiC, Moss + T2, or Moss + T2 + TiC + Mo2C eutectic reaction took place as the secondary solidification step. In some alloys, Moss + T2 + TiC and Moss + T2 + Mo2C eutectic reactions were present as higher-order solidification steps. After annealing at 2073 K (1800 °C) for 24 hours, Moss, T2, TiC, and Mo2C coexisted stably with microstructural coarsening. The coarsening rate was much faster in an alloy with no TiC dispersion, suggesting that TiC has a strong pinning effect on the grain boundary and interface migration. Compression tests conducted at 1673 K (1400 °C) revealed strength properties of almost all the alloys that were better than those of the Mo-Hf-C alloy (MHC). Alloy densities were 9 g/cm3 or less, which is lighter than pure Mo and MHC (≥10 g/cm3) and competitive with Ni-base superalloys. TiC-added Mo-Si-B alloys are promising candidates for ultrahigh-temperature materials beyond Ni-base superalloys.

Creep rupture life and microstructural degradation have been studied in two heats of Gr.91 steels. The coarsening of subgrains and precipitates, mainly M23C6 and MX, has been evaluated during static aging and creep. Hardness of head (static aging) and gauge (creep) portions of crept samples were measured to know their relation with microstructural degradation during long-term exposure. The correlation between subgrain size and spacing of precipitates and hardness has been equated. As an example, there is a close correlation between hardness value and inverse subgrains size in Gr.91 steels, regardless of aging or creep conditions. The appearance of three recovery mechanisms was found during long-term creep, namely: strain-induced recovery, pure static recovery and strain-assisted static recovery. By equated correlations between subgrain size, precipitates and hardness, the contribution of three recovery mechanisms to subgrain coarsening and hardness drop were calculated for two creep conditions at 700 °C in long-term creep region, where breakdown of creep strength has happen. The calculated data accord well with experimental data obtained from aged and crept samples. The contribution of static recovery to the subgrain coarsening and consequent hardness drop during long-term creep increases with increasing creep time. The significant contribution of both static recovery mechanisms can result in the breakdown of creep strength in long-term creep region.

Previous in vitro and in vivo studies showed that sodium orthovanadate (vanadate), an inorganic vanadium compound, could effectively suppress radiation-induced p53-mediated apoptosis via both transcription-dependent and transcription-independent pathways. As a potent radiation protector administered at a dose of 20 mg/kg body weight (20 mg/kg) prior to total-body irradiation (TBI) by intra-peritoneal (ip) injection, it completely protected mice from hematopoietic syndrome and partially from the gastrointestinal syndrome. In the present study, radiation mitigation effects from vanadate were investigated by ip injection of vanadate after TBI in mice. Results showed that a single administration of vanadate at a dose of 20 mg/kg markedly improved the 30-day survival and the peripheral blood hemogram, relieved bone marrow aplasia and decreases occurrence of the bone marrow micronucleated erythrocytes in the surviving animals. The dose reduction factor was 1.2 when a single dose of 20 mg/kg was administrated 15 minutes after TBI in mice using the 30-day survival test as the endpoint. Results also showed that either doubling the vanadate dose (40 mg/kg) in a single administration or continuing the vanadate treatment (after a single administration at 20 mg/kg) from the following day at a dose of 5 mg/kg per day for 4 consecutive days would further significantly improved the efficacy for rescuing bone marrow failure in the 30-day survival test. Taken together, these findings indicate that vanadate would be a potent mitigator suppressing the acute lethality (hematopoietic syndrome) and minimizing the detrimental effects (anhematopoiesis and delayed genotoxic effects) induced by TBI in mice.

Creep rupture strength of creep strength enhanced ferritic steels is often overestimated, and its evaluated value has been reduced repeatedly. In this paper, the cause of the overestimation is discussed, and the creep rupture strength of T91 steel is assessed with its updated creep rupture data. Effects of residual Ni concentration on the creep rupture strength and necessity of F factor in T91 steel are also discussed. Decrease in activation energy Q for rupture life in long-term creep is the cause of the overestimation, since conventional time–temperature parameter (TTP) methods cannot deal with the change in Q. Due to the decrease in Q, long-term creep rupture strength evaluated decreases as longer-term data points are added or shorter-term data points are discarded in the conventional TTP analysis. The long-term region with small values of activation energy and stress exponent is named region L2 in this paper. Region L2 appears in all the heats of T91 steel and plate products of Gr.91 steel. Since service conditions of the T91 steel are usually in region L2, the creep rupture strength under the service conditions should be evaluated from the rupture data in region L2 only. The 5 × 105 hrs rupture strength at 550 °C decreases from 129 MPa (evaluated from the whole data of T91 steel) to 79 MPa (evaluated from the data in region L2 only) with increasing cut-off time for data selection. The 105 hrs rupture strength at 600 °C also decreases from 87 MPa (whole data) to 70 MPa (region L2 only) despite sufficient number of long-term data points at 600 °C. Careful consideration on the data selection is necessary in evaluation of creep rupture strength of the T91 steel. A multiregion rupture data analysis (MRA) is helpful to select data points belonging to region L2.

BACKGROUND Adaptive response (AR) of low linear energy transfer (LET) irradiations for protection against teratogenesis induced by high LET irradiations is not well documented. In this study, induction of AR by X-rays against teratogenesis induced by accelerated heavy ions was examined in fetal mice. METHODS Irradiations of pregnant C57BL/6J mice were performed by delivering a priming low dose from X-rays at 0.05 or 0.30 Gy on gestation day 11 followed one day later by a challenge high dose from either X-rays or accelerated heavy ions. Monoenergetic beams of carbon, neon, silicon, and iron with the LET values of about 15, 30, 55, and 200 keV/μm, respectively, were examined. Significant suppression of teratogenic effects (fetal death, malformation of live fetuses, or low body weight) was used as the endpoint for judgment of a successful AR induction. RESULTS Existence of AR induced by low-LET X-rays against teratogenic effect induced by high-LET accelerated heavy ions was demonstrated. The priming low dose of X-rays significantly reduced the occurrence of prenatal fetal death, malformation, and/or low body weight induced by the challenge high dose from either X-rays or accelerated heavy ions of carbon, neon or silicon but not iron particles. CONCLUSIONS Successful AR induction appears to be a radiation quality event, depending on the LET value and/or the particle species of the challenge irradiations. These findings would provide a new insight into the study on radiation-induced AR in utero.

Titanium aluminide (TiAl) alloys exhibit high specific strength, low density, good oxidation, corrosion, and creep resistance at elevated temperatures, making them good candidate materials for aerospace and automotive applications. TiAl alloys also show excellent radiation resistance and low neutron activation, and they can be developed to have various microstructures, allowing different combinations of properties for various extreme environments. Hence, TiAl alloys may be used in advanced nuclear systems as high-temperature structural materials. Moreover, TiAl alloys are good materials to be used for fundamental studies on microstructural effects on irradiation behavior of advanced nuclear structural materials. This article reviews the microstructure, creep, radiation, and oxidation properties of TiAl alloys in comparison with other nuclear structural materials to assess the potential of TiAl alloys as candidate structural materials for future nuclear applications.

Existence of adaptive response (AR) was previously demonstrated in C57BL/6J mice. Irradiations were performed by delivering a priming low dose of X-rays (0.50 Gy) in combination with a challenge high dose of accelerated carbon or neon ion particles. AR was characterized by significantly decreased mortality in the 30-day survival test. This mouse AR model (Yonezawa Effect) was originally established by using X-rays as both the priming and challenge irradiations. The underlying mechanism was due to radio-resistance oc- curring in blood-forming tissues. In this study, we verified the existence of AR and further investigated re- sidual damage in the hematopoietic system in surviving animals. Results showed that the priming low dose of X-rays could relieve the detrimental effects on the hematopoietic system. We observed both an improve- ment in the blood platelet count and the ratio of polychromatic erythrocytes (PCEs) to the sum of PCEs and normochromatic erythrocytes (NCEs) and a marked reduction of the incidences of micronucleated PCEs and micronucleated NCEs. These findings suggest that the priming low dose of low linear energy transfer (LET) X-rays induced a protective effect on the hematopoietic system, which may play an important role in both rescue from acute lethal damage (mouse killing) and prevention of late detrimental consequences (re- sidual anhematopoiesis and delayed genotoxic effects) caused by exposure to a high challenge dose from low-LET (X-ray) or high-LET (carbon and neon ion) irradiations. These findings provide new knowledge of the characterization of the Yonezawa Effect by providing new insight into the mechanistic study of AR in vivo.

Feline McDonough Sarcoma (FMS)-like tyrosine kinase 4 (FLT4) is a marker for lymphatic vessels and some high endothelial venules in human adult tissues. We generated a transgenic medaka fish in which the lymphatic vessels and some blood vessels are visible in vivo by transferring the promoter of medaka flt4 driving the expression of enhanced green fluorescent protein (EGFP) using a see-through medaka line. To do this, we identified and cloned medaka flt4 and generated a construct in which the promoter was the 4-kb region upstream of the translation initiation site. The fluorescent signal of EGFP could be observed with little background, and the expression pattern correlated well with that of flt4 determined by whole-mount RNA in situ hybridization. Because a see-through medaka line is transparent until adult, the model is useful for visualizing the lymphatic vessels not only in embryo and fry but also in adult. This model will be a useful tool for analyzing lymphatic development.

Single-phase regions in Mo-rich Mo–Si–B alloys at 1800 °C were experimentally determined using a field-emission (FE) gun-type electron probe micro-analyzer (EPMA) in this study. A quantitative analysis by FE-EPMA was conducted with the calibration method we applied in our previous study to improve the accuracy in the B measurements. The compositional ranges of the determined Mo solid solution, silicide and boride phases were in good agreement with those of Mo–Si and Mo–B binary phase diagrams. On the other hand, the determined solubility of B in Mo solid solution, Mo 3 Si and T 1 (Mo 5 Si 3 ) were quite different from that indicated in previously reported ternary phase diagrams. The compositional region of the T 2 (Mo 5 SiB 2 ) single-phase ranges from 9.7 to 13.3 at% for Si and from 23.5 to 26.8 at% for B. The following two points were made clear by the ternary phase diagram as determined in this study. One is that no stoichiometric T 2 composition is in the T 2 single-phase region, confirming no T 2 single-phase material can be obtained at the stoichiometric composition at 1800 °C. The another is that the T 2 region of this study expands to a Si-rich area from the stoichiometric composition.

A major breakthrough in in vivo cellular imaging has been the clinical/preclinical use of magnetic resonance imaging (MRI) with contrast agent. Superparamagnetic iron oxide (SPIO) is a promising candidate for the development of smart MRI probes for cell-tracking. In the present study, we describe biodegradable probes made of giant vesicles (GVs; closed lipid membranes with diameters >1 μm) that encapsulate SPIO for use as an MRI contrast agent. These SPIO-containing GVs (SPIO-GVs) exhibited excellent contrast enhancement in the single cell of medaka fish (Oryzias latipes) embryos immediately after their microinjection, and this enhancement disappeared when the GV membranes were destroyed. Our results demonstrate that SPIO-GVs are useful MRI probes for single cell-tracking that have minimum cytotoxicity and will greatly improve clinical/preclinical in vivo cellular imaging techniques.

The microstructures of thixomolded® (TM) Mg-Al-Ca alloys consist of α-Mg and eutectic compounds along grain boundaries. Misch metal (Mm) addition to TM Mg-Al-Ca alloys makes precipitates within α-Mg matrix and their number density and size depend on heat-treatment conditions. The small addition of Mm can keep the network-like grain boundary covering and the improvement of microstructure stability during creep. On the other hand, excessive Mm addition causes the deterioration of creep strength. The grain boundary coverage decreases with increasing Mm content due to the formation of coarse spherical Al-Mm based intermetallic compounds. Creep strength is significantly affected by both of the grain boundary coverage and the morphology of eutectic compounds along grain boundaries.

Hemoglobin of bony fish and higher vertebrates is a tetrameric protein constructed by 2 α- and 2 β-globins, which are expressed in a developmental stage-specific manner. The genomic organization of genes for embryonic and adult α- and β-globin varies from species to species. In fish, it is known that there is a unique genomic organization of globin genes, that is, α- and β-globin genes are arranged in a bi-directional and head-to-head orientation with respect to transcription start sites. In medaka, we have demonstrated that 14 globin genes are located in 2 different clusters, and 5 pairs of the α- and β-globin genes were found to be organized in a head-to-head orientation. The developmental expression patterns of the 11 globin genes were classified into 4 types. To clarify how their developmental stage-specific expressions are regulated, we produced 4 types of GFP- or RFP-transgenic medaka. Such transgenic medaka revealed that each of the 1–1.7 kbp 5′ upstream sequences from respective globin genes possesses the ability to regulate the developmental stage-specific globin gene expression. In particular, the intervals between head-to-head α3 and β3, and α4 and β4 genes controlled the synchronized expression of the globin genes located at both sides of the intervals, which is significant to understand the mechanism by which equal amounts of α- and β-globins are expressed in erythroid cells. We also demonstrated that the head-to-head intervals can control the expression of the globin genes located at both sides. These findings are significant to understand the mechanism by which α- and β-globins are equally expressed in erythroid cells.

Strain-induced coarsening of precipitates, mainly M23C6, has been studied in several types of Gr. 122, Gr. 92 and Gr. 91 steels in a wide range of creep conditions. Strain-induced coarsening of precipitates should be separately evaluated in high stress and short-term creep region (or called “H”), where precipitates and subgrains are thermally stable, and low stress in long-term creep region (or called “L”), where thermal coarsening of precipitates and subgrains appear. Creep plastic deformation does not accelerate the coarsening of precipitates during the primary and secondary creep regions in short-term creep region “H”. However, the coarsening of M23C6 precipitates occurs during the acceleration creep region and increases with decreasing of applied stress. The onset of long-term region “L” is accompanied by the thermal coarsening of M23C6 precipitates as well as strain-induced coarsening of M23C6 precipitates during secondary and acceleration creep regions and maybe in primary creep region under very low creep stress. In long-term region “L”, recovery of the dislocation substructure is controlled simultaneously by creep plastic deformation and pinning force from precipitates. On the other hand, the coarsening of precipitates is due to both thermal coarsening and strain-induced coarsening of precipitates. In fact, the stability of precipitates is the most important factor for the suppression of subgrain recovery in long-term region “L” rather than short-term creep region “H”. In long-term region “L”, greater thermal recovery of subgrains and M23C6 precipitates due to higher creep temperature or/and longer creep rupture life results in greater strain-induced coarsening of M23C6 precipitates.

There are two creep regions with different creep characteristics: short-term creep region “H”, where precipitates and subgrains are thermally stable, and long-term creep region “L”, where thermal coarsening of precipitates and subgrains appear. In region “H”, the normalized subgrain size ( λ - λ 0 ) / ( λ ∗ - λ 0 ) has a linear relation with creep strain and its slope is 10 e −1 . But, region L is the time range in which the static recovery and the strain-induced recovery progress simultaneously. In this region, the static recovery accelerates the strain-induced recovery, and subgrain size is larger than that line which neglects the contribution of the static recovery. In region “L”, the Δ λ / Δ λ ∗ -strain present a linear relation with a slope 35 e −1 . There is a linear relation between hardness and subgrain size. Hardness drop, H 0 − H , as a function of Larson–Miller parameter can be a good measure method for assessment of hardness drop and consequently degradation of microstructure. Hardness drop shows an identical slope in creep region “H”, whereas hardness drop due to thermal aging and creep in region “L” show together a similar slope. In region “H”, degradation of microstructure is mainly due to recovery of subgrains controlled by creep plastic deformation, and precipitates do not have a major role. However, in creep region “L”, there are three degradation mechanisms that accelerate creep failure; (1) strain-induced recovery of subgrains due to creep plastic deformation, (2) static-recovery of subgrains and precipitates and (3) strain-induced coarsening of precipitates due to the appearance of static-recovery.

First of all, the as-cast microstructures of Mo-rich Mo-Si-B ternary alloys were investigated around the triple junction point of the primary Mo solid solution, Mo5SiB2 and Mo2B in this work, based on the liquidus projections of the Mo-Si-B system which have been reported in earlier studies. Subsequently, their microstructural evolution through heat treatment was investigated. Since Mo2B crystallizes out during solidification into a primary or secondary phase even though the alloy composition lies in the triangle of Mo-Mo5SiB2-Mo3Si in the Mo-Si-B equilibrium phase diagram, the as-cast microstructures include the non-equilibrated Mo2B in wide compositional ranges. However, Mo2B was completely decomposed during heat treatment at 1800 °C for 24 h and this contributed to the development of homogeneous, fine microstructures. On the other hand, since Mo2B was not decomposed perfectly during 24 h of 1600 °C heat treatment, as-cast microstructures largely remained. Therefore, it is realized that the heat treatment at 1800 °C is necessary to obtain well-developed microstructures of Mo-Si-B alloys.

Creep behavior and degradation of subgrain structures and precipitates of Gr. 122 type xCr-2W-0.4Mo-1Cu-VNb (x = 5, 7, 9, 10.5, and 12 pct) steels were evaluated during short-term and long-term static aging and creep with regard to the Cr content of steel. Creep rupture life increased from 5 to 12 pct Cr in the short-term creep region, whereas in the long-term creep region, it increased up to 9 pct Cr and then decreased with the addition of Cr from 9 to 12 pct. Behavior of creep rupture life was attributed to the size of elongated subgrains. In the short-term creep region, subgrain size decreased from 5 to 12 pct Cr, corresponding to the longer creep strength. However, in the long-term creep region after 104 hours, subgrain size increased up to 9 pct Cr and then decreased from 9 to 12 pct, corresponding to the behavior of creep rupture life. M23C6 and MX precipitates had the highest number fraction among all of the precipitates present in the studied steels. Cr concentration dependence of spacing of M23C6 and MX precipitates exhibited a V-like shape during short-term as well as long-term aging at 923 K (650 °C), and the minimum spacing of precipitates belonged to 9 pct Cr steel, corresponding to the lowest recovery speed of subgrain structures. In the short-term creep region, subgrain coarsening during creep was controlled by strain and proceeded slower with the addition of Cr, whereas in long-term creep region, subgrain coarsening was controlled by the stability of precipitates rather than due to the creep plastic deformation and took place faster from 9 to 12 pct and 9 to 5 pct Cr. However, M23C6 precipitates played a more important role than MX precipitates in the control of subgrain coarsening, and there was a closer correlation between spacing of M23C6 precipitates and subgrain size during static aging and long-term creep region.

The cause of the breakdown of creep strength has been studied in Gr.91 steel. The results show that the contribution of the static recovery of subgrains to creep deformation causes the breakdown of creep strength. The subgrain boundaries are mainly stabilized by M23C6 and MX precipitates. MX precipitates are thermally stable even in the time range when coarsening of subgrains takes place. Whereas M23C6 precipitates are not thermally stable and the aggregation of M23C6 precipitates takes place in the time range when coarsening of subgrains happens. Therefore, loss of pinning force from M23C6 precipitates is responsible for the static recovery of subgrains. MX has nothing to do with the static recovery. The microstructural stability of Gr.91 steel in the time range longer than 105 h at 600 °C has also been assessed based on the creep data of Gr.91 steel tested up to 90,408 h at 600 °C and 22,900 h at 650 °C. The aggregation of precipitates and the coarsening of subgrains start to take place at round 105 h at 600 °C. Therefore, the breakdown of creep strength is expected to happen in the time range a little longer than 105 h at 600 °C.

Some studies for radiological protection of the environment have been made at the National Institute of Radiological Sciences (NIRS). Transfer of radionuclides and related elements has been investigated for dose estimation of non-human biota. A parameter database and radionuclide transfer models have been also developed for the Japanese environments. Dose (rate)-effect relationships for survival, growth and reproduction have been investigated in conifers, Arabidopsis, fungi, earthworms, springtails, algae, duckweeds, daphnia and medaka. Also genome-wide gene expression analysis has been carried out by high coverage expression profiling (HiCEP). Effects on aquatic microbial communities have been studied in experimental ecosystem models, i.e., microcosms. Some effects were detected at a dose rate of 1 Gy day(-1) and were likely to arise from interspecies interactions. The results obtained at NIRS have been used in development of frameworks for environmental protection by some international bodies, and will contribute to environmental protection in Japan and other Asian countries.

In this article, our recent advances on supersaturated vacancy behavior in rapidly quenched FeAl investigated by DSC measurements coupled with TEM observations are reviewed. There are two exothermic peaks only at the first heating step of DSC for the rapidly quenched FeAl. The 1st peak is small and lies in a lower temperature range, and the 2nd peak is large lying in a higher temperature range. The apparent activation energy of the exothermic reactions changes not only with Al concentration but also with quenching temperature. This indicates that the apparent activation energy is not the material constant of FeAl but a variable that changes with the concentration of supersaturated thermal vacancies. The 2nd peak corresponds to the nucleation and growth of vacancy clusters and complexes inside the bulks due to the condensation and annihilation of supersaturated vacancies, i.e. the formation and growth of cuboidal voids for rapidly solidified ribbons and of 〈100〉-type prismatic loops for water-quenched single crystals. The morphology of the vacancy complexes grown under the 2nd peak is correctly expressed by the Johnson–Mehl–Avrami (JMA) equation extended by Matusita et al. for the DSC curves: the morphology factor, m, nearly equals to 2 for the formation and growth of 〈100〉-type prismatic loops and to 3 for those of cuboidal voids. Therefore, the extended JMA method would be useful to judge the morphology of vacancy complexes.

Creep rupture data and microstructural degradation during aging of high Cr ferritic boiler steels with enhanced creep strength have been studied with special attention to prediction of long term creep rupture life. Tempered lath martensite structure in the high Cr ferritic steels remains unchanged during short term aging, whereas static recovery of the lath martensite structure proceeds when diffusion distance during aging becomes sufficiently long as is the case in long term creep. The static recovery brings about premature failure in long term creep and decreases in apparent activation energy for creep life. The decrease in activation energy is responsible for overestimation of rupture life reported in strength enhanced high Cr ferritic steels. The boundary from a short term region with high activation energy QH to a long term region with low activation energy QL moves towards longer time with decreasing Cr concentration. The difference in activation energy (QH − QL) primarily determines the extent of overestimation of rupture life predicted from short term data. In general, the extent of overestimation is less serious at 9%Cr as compared to 12%Cr.

Compressive creep behavior of hot-rolled (40%) Mg-Y and Mg-Y-Zn alloys are investigated at 480 ~ 650 K. Creep strength is substantially improved by the simultaneous addition of yttrium and zinc. The minimum creep rate of Mg-0.9mol%Y-0.04mol%Zn (WZ301) alloy decreases to 1/10 lower than that of Mg-1.1mol%Y (W4) alloy at 650 K. Activation energy for creep in W4 and WZ301 alloys are more than 200 kJ/mol at the temperature range of 480 ~ 550 K. These values are higher than the activation energy for self-diffusion coefficient in magnesium (135 kJ/mol). Many stacking faults (planar defects, PDs) are only observed on the basal planes of the matrix in Mg-Y-Zn ternary alloys. Stacking fault energy is considered to decrease by the multiple-addition of yttrium and zinc. The size and density of these planar defects depend on solute content, aging condition. TEM observation has been revealed that the decreasing of the stacking fault energy affects the distribution of dislocations during creep. Many a-dislocations on basal planes are extended significantly. Dislocation motion is restricted significantly by both of these two types of stacking faults (planar type and extended dislocations).

The phase formation behavior during solidification in the Mo-Si-B system was experimentally examined around the triple junction point (T) of the Mo solid solution (Mo SS ), Mo 5 SiB 2 (T 2 ) and Mo 2 B primary phases in the Mo-Si-B liquidus projection suggested by Yang and Chang through thermodynamic calculations, and the solidification routes of the Mo-Si-B alloys were reconsidered based on the obtained results. Alloys of four different compositions around the T point were produced by arc-melting. The primary phases observed in these alloys were in excellent agreement with the liquidus projection proposed by Yang and Chang. The solidification routes were basically Mo SS (primary) → Mo SS + Mo 2 B → Moss + T 2 eutectic → Moss + T 2 + Mo 3 Si (A15), T 2 (primary) → Mo SS + T 2 eutectic → Mo SS + T 2 + A15, or Mo 2 B (primary) → Moss + T 2 eutectic → Moss + T 2 + A15, depending on the composition. However, a quantitative EPMA analysis indicated the compositions of the Mo SS -T 2 eutectic and Moss + T 2 + A15 phases differed from the reported liquidus projection. This is due to the difficulties interpreting the unusual solidification routes in the Mo-Si-B system and their as-cast microstructures.

β phase can be introduced to TiAl alloys by the additions of β stabilizing elements such as Cr, Nb, W, and Mo. The β phase has a body-centered cubic lattice structure and is softer than the α2 and γ phases in TiAl alloys at elevated temperatures, and hence is thought to have a detrimental effect on creep strength. However, fine β precipitates can be formed at lamellar interfaces by proper heat treatment conditions and the β interfacial precipitate improves the creep resistance of fully lamellar TiAl alloys, since the phase interface of γ/β retards the motion of dislocations during creep. This paper reviews recent research on high-temperature strengthening behavior of the β phase in fully lamellar TiAl alloys.

Creep rupture life in the time range of 105 h and longer has been evaluated on the basis of creep rupture data available on modified 9Cr–1Mo (Gr.91) steel. The steel is strengthened by a tempered martensite lath structure, which degrades by means of strain induced recovery in short-term creep (Region H). The degradation leads to creep rupture. In long-term creep (Region L), static recovery of the martensite lath structure takes place in addition to the strain induced recovery, resulting in premature creep rupture and the consequent decrease in stress exponent n for rupture life. The premature creep rupture always occurs in Gr.91 steel, but the activation energy QL for rupture life in region L is usually close to the value QH in Region H in the steel. In such a case, long-term rupture life can be predicted correctly by simple extrapolation of short-term data. In some heats of Gr.91 steel, however, another region with low values of n and Q, namely Region L2, appears in the time range longer than 104 h. Simple extrapolation of short-term data results in overestimation of rupture life in Region L2. The static recovery and the consequent premature creep rupture are controlled by migration of sub-boundaries stabilized by precipitates. M23C6 as well as MX precipitates in Gr.91 steel have higher thermal stability than those in other high Cr ferritic steels, resulting in the later appearance or absence of Regions L and L2 in the steel.

The recent success with small fish as an animal model of cancer with the aid of fluorescence technique has attracted cancer modelers' attention because it would be possible to directly visualize tumor cells in vivo in real time. Here, we report a medaka model capable of allowing the observation of various cell behaviors of transplanted tumor cells, such as cell proliferation and metastasis, which were visualized easily in vivo. We established medaka melanoma (MM) cells stably expressing GFP and transplanted them into nonirradiated and irradiated medaka. The tumor cells were grown at the injection sites in medaka, and the spatiotemporal changes were visualized under a fluorescence stereoscopic microscope at a cellular-level resolution, and even at a single-cell level. Tumor dormancy and metastasis were also observed. Interestingly, in irradiated medaka, accelerated tumor growth and metastasis of the transplanted tumor cells were directly visualized. Our medaka model provides an opportunity to visualize in vivo tumor cells “as seen in a culture dish” and would be useful for in vivo tumor cell biology.

Certain β forming atoms, such as W, segregate into α2 plates and form precipitation bands of β0 particles during dissolution of α2 plates at high temperature. Creep properties of TiAl alloys containing β0 precipitates are studied, and their microstructural and alloy design is discussed on the basis of microstructural changes occurring in the alloys. Precipitation bands of β0 particles reduce minimum creep rate and extend time to 1% strain and rupture life of the alloys. Creep resistance of the alloys is as good as a hard-oriented polysynthetically twinned crystal of a TiAl alloy. α2 plates thicker than a critical size is necessary to form the precipitation bands and utilize the benefits of precipitation strengthening. Microstructural degradations, such as agglomeration and dissolution of β0 particles and dynamic recrystallization play significant roles in long-term creep. Retardation of the particle degradations is necessary to make efficient use of the strengthening by β0 precipitates.

Long-term creep rupture strengths and the microstructural stability of ASME P92 and P122 pipes have been studied using creep testing at the temperatures from 550 to 700 °C and detailed scanning transmission electron microscopy. Creep rupture strength of P92 is found to be more stable than that of P122 at temperatures over 600 °C, which is mainly due to the difference in their Cr content. P122 type model steel with reduced Cr content, 9%Cr, has been prepared to explore the effect of Cr on the stability of MX and formation of Z-phase during creep deformation. MX in 9%Cr steel is found to be stable even after prolonged exposure at 650 °C, while Cr and Fe concentration to MX without marked coarsening has been observed in 10.5%Cr steel after aging for 10,000 h at 650 °C. This seems to lead to the transition of MX carbonitride into the Z-phase after aging for 23,000 h, which requires ordering in a M 2 N lattice to achieve a tetragonal Z-phase to be stable. Creep deformation behavior in the transient creep region of the steels is almost same up to about 7000 h, while in the acceleration creep region the creep rate of 10.5%Cr steel becomes much faster than that of 9%Cr steel, resulting in shorter rupture life. It is obvious that the creep rupture strength degradation starts prior to the formation of Z-phase in 10.5%Cr steel. It is thus concluded that Z-phase is not a necessary factor for degradation of creep rupture strength but the instability of the fine precipitates such as Cr 2 (C, N) caused by the compositions change like Cr supply to MX carbonitride is more essential.

Samarium (Sm) additions to as-cast Mg-5Al-3Ca-based alloys result in changes, such as equiaxed grains and a refined grain size. The microstructure of as-cast Mg-5Al-3Ca- x Sm alloys consists of an α-Mg matrix, a (Mg, Al) 2 Ca eutectic phase, and an Al 2 Sm intermetallic compound. In as-cast alloys, the (Mg, Al) 2 Ca eutectic phase was located at grain boundaries with a chain structure, and the Al 2 Sm intermetallic compounds were homogeneously distributed at the α-Mg matrix and grain boundaries. The eutectic phase of the extruded alloys was elongated in the extrusion direction and crushed into fine particles because of severe deformation during hot extrusion, and the grain size was refined with an increased amount of Sm addition. The maximum values of the yield strength and tensile strength were 313 MPa and 330 MPa at 2 wt%Sm alloy content, respectively.

During thixomolding ® of Mg alloys, fine grains (size of ∼ 10 μm) and continuous eutectic compounds are formed along grain boundaries. These compounds are partly responsible for the superior creep strength of Mg alloys. In this study, we investigate the effects of eutectic compounds formed along grain boundaries in thixomolded ® Mg 96 Zn 2 Y 2 on creep deformation at 573 K. By performing microstructure analyses, we find that two types of continuous eutectic compounds―Mg 3 Y 2 Zn 3 and Mg 12 YZn―are formed in the alloy. The strain rate of Mg 96 Zn 2 Y 2 is about two orders of magnitude lower than that of a heat-resistant alloy Mg 93 Al 5 Ca 2 (Mg-6 mass%Al-3 mass%Ca) at 573 K. The stress exponent n at 573 K is approximately 7, and it is considered that creep deformation is controlled by dislocation motion. All scribe lines produced on a specimen of Mg 96 Zn 2 Y 2 are curved. Furthermore, in the case of a specimen with a creep strain of 7%, no abrupt steps are observed at grain boundaries and interfaces between the α-Mg matrix and eutectic compounds. Our results indicate that eutectic compounds formed along grain boundaries are effective in suppressing grain boundary sliding.

This paper summarizes research activities in National Institute of Radiological Sciences (NIRS) for evaluation of the radiation effects on selected terrestrial and aquatic organisms as well as the ecosystems. Seven organisms, conifers, fungi, earthworms, springtails, algae, daphnia and Medaka are presently selected to study. For the estimation of possible radiation dose, transfers of radionuclides and related elements from medium to organisms are evaluated. Dose-effect relationships of acute gamma radiation on the survival, growth, and reproduction of selected organisms have been studied. Studies on the effect of chronic gamma radiation at low dose rate were also started. In order to understand the mechanism of radiation effects and to find possible indicators of the effects, information of genome- and metagenome-wide gene expression has been collected. Evaluation of ecological effects of radiation is more challenging task. Study methods by using three-species microcosm were established, and an index for the holistic evaluation of effects on various ecological parameters was proposed. The microcosm has been simulated as a computer simulation code. Developments of more complicated and practical model ecosystems have been started. The Denaturant Gradient Gel Electrophoresis (DGGE) has been applied on soil bacterial community in order to evaluate the radiation effects on soil ecosystems., International Conference on Radioecology & Environmental Radioactivity

Developing neural tubes are bilaterally symmetric in all vertebrate embryos, irrespective of the presence of gene networks that generate left-right asymmetry. To explore the mechanisms that underlie the bilaterally symmetric formation of the neural tube, we examined a medaka (Oryzias latipes) dominant mutant, Oot, the neural tube of which transiently lacks normal symmetry in the optic tectum. We found that spatial changes in isthmic fgf8 expression do not occur on one side of the mutant, resulting in a transient desynchronized expression that correlates with tectal asymmetry. The application of exogenous FGF8 on one side of a wild-type embryo mimics the Oot phenotype, indicating that the bilaterally equivalent expression of isthmic fgf8 is crucial for the bilaterally symmetric development of the tectum. These results suggest that tectal symmetry is not a “default” state, but rather is maintained actively by a bilaterally coupled and synchronized regulation of isthmic fgf8 expression. genesis 46:537–545, 2008. © 2008 Wiley-Liss, Inc.

In FeAl, the effects of supersaturated thermal vacancies, their self-assembling on nano- to micro-structures, and their mechanical properties, are significant. In this study, the self-assembling behavior of supersaturated thermal vacancies was investigated with single-crystals using differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). An irreversible exothermic peak was detected in as-quenched crystals by DSC. Isochronal changes of surface morphology and substructure around the exothermic peak temperature were observed by TEM. The average size of the surface pores increased uniformly with increasing temperature. Dislocations whose Burgers vectors were parallel to 〈1 0 0〉 existed in the isochronally heated crystals and their density varied with temperature. However, there was a dislocation-free zone extending from the surface to a depth of several tens of nanometers, indicating that supersaturated thermal vacancies in this zone were completely exhausted to form surface pores. A growth model of the surface pores is discussed based on the results.

Long-term creep rupture life is often evaluated from short-term data by a time–temperature parameter (TTP) method. However the conventional TTP methods sometimes fail in understanding creep rupture behavior of strength enhanced high Cr ferritic steels and overestimate creep rupture life in long-term creep. In the present paper, creep rupture data of seven kinds of heat resistant steels with different W and Cr concentrations have been analyzed. The conventional TTP method like Orr–Sherby–Dorn analysis evaluates long-term creep rupture life assuming a unique value of activation energy for all the creep rupture data. This analysis is called single region analysis in this paper. The single region analysis can represent well the creep rupture data of steels containing less than 8% Cr. The creep rupture analyses of steels containing more than 8% Cr exhibit that apparent activation energy changes from a high value in short-term creep region to a low value in long-term creep region. In each case a creep data was divided into several data sets, and then the conventional single region analysis was applied to each divided data set. This analysis is referred to as multiregion analysis. The multiregion analysis describes very well all the data points, whereas regression curves of the single region analysis deviate from the data points, resulting in overestimation of long-term rupture life. The difference between the two activation energies of short-term and long-term creep increases with increasing Cr concentration. Therefore, the overestimation due to singles region analysis is expected to be more serious at higher Cr concentration.

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Creep behavior of lamellar Ti–45Al–8Nb–0.2C (in mol%) alloy was studied paying special attention to microstructural degradation during creep. Minimum creep rate of Ti–45Al–Nb–C is reduced to 25% of that of binary Ti–45Al. Nb retards recovery of dislocations. Nb and C addition stabilizes lamellar microstructure. As a result, lower minimum creep rate and slower creep acceleration in tertiary creep are attained in the TiAl alloy with Nb and C.

The cerebellar structures of teleosts are markedly different from those of other vertebrates. The cerebellum continues rostrally into the midbrain ventricle, forming the valvula cerebelli, only in ray-finned fishes among vertebrates. To analyze the ontogenetic processes that underlie this morphological difference, we examined the early development of the cerebellar regions, including the isthmus (mid/hindbrain boundary, MHB), of the medaka (Oryzias latipes), by histology and in-situ hybridization using two gene (wnt1 and fgf8) probes. Isthmic wnt1 was expressed stably in the caudalmost mesencephalic region in the neural tube at all developmental stages examined, defining molecularly the caudal limit of the mesencephalon. The wnt1-positive mesencephalic cells became located rostrally to the isthmic constriction at Iwamatsu's stages 25-26. Isthmic fgf8 expression changed dynamically and became restricted to the rostralmost metencephalic region at stage 24. The rostralmost part (prospective valvula cerebelli) of the fgf8-positive rostral metencephalon protruded rostrally into the midbrain ventricle, bypassing the isthmic constriction, at stages 25-26. Thus, the isthmic constriction shifted caudally with respect to the molecularly defined MHB at stages 25-26. Paired cerebellar primordia were formed from the alar plates of the fgf8-positive rostral metencephalon and the fgf8-negative caudal metencephalon in the medaka neural tube. Our results show that cerebellar development differs between teleosts and murines: both the rostral and caudal metencephalic alar plates develop into the cerebellum in medaka, whereas in the murines only the caudal metencephalic alar plate develops into the cerebellum, and the rostral plate is reduced to a thin membrane.

The as-cast microstructure of Mg-5Al-3Ca-xY alloy consists of dendritic � -Mg matrix, (Mg, Al)2Ca eutectic phase and Al2Y intermetallic compounds. These two kind of (Mg, Al)2Ca compounds were observed: coarse irregular-shape structure at grain boundary and fine needle-shape structure in the � -Mg matrix grain. This (Mg, Al)2Ca phase of the extruded alloys was elongated to extrusion direction and size of this phase was refined comparing with that of as-cast alloys because of severe deformation during hot extrusion. Maximum yield and ultimate strength value of extruded alloys was 326 and 331 MPa at Mg-5Al-3Ca-3Y alloy, respectively. From these results, it is conclusively demonstrated that Y additions on Mg-5Al-3Ca alloy have more effect to improve mechanical properties. [doi:10.2320/matertrans.MC200777]

We describe a novel method for rapid and quantitative evaluation of the degree of radiation-induced apoptosis in the developing brain of medaka (Oryzias latipes). Embryos at stage 28 were irradiated with 1, 2, 3.5, and 5 Gy x-ray. Living embryos were stained with a vital dye, acridine orange (AO), for 1-2 h, and whole-mount brains were examined under an epifluorescence microscope. From 7 to 10 h after irradiation with 5 Gy x-ray, we found two morphologically different types of AO-stained structures, namely, small single nuclei and rosette-shaped nuclear clusters. Electron microscopy revealed that these two distinct types of structures were single apoptotic cells with condensed nuclei and aggregates of apoptotic cells, respectively. From 10 to 30 h after irradiation, a similar AO-staining pattern was observed. The numbers of AO-stained rosette-shaped nuclear clusters and AO-stained single nuclei increased in a dose-dependent manner in the optic tectum. We used the number of AO-stained rosette-shaped nuclear clusters/optic tectum as an index of the degree of radiation-induced brain cell death at 20-24 h after irradiation. The results showed that the number of rosette-shaped nuclear clusters/optic tectum in irradiated embryos exposed to 2 Gy or higher doses was highly significant compared to the number in nonirradiated control embryos, whereas no difference was detected at 1 Gy. Thus, the threshold dose for brain cell death in medaka embryos was taken as being between 1-2 Gy, which may not be so extraordinarily large compared to those for rodents and humans. The results show that medaka embryos are useful for quantitative evaluation of developmental neurocytotoxic effects of radiation.

High temperature creep strength at 650 K and microstructures of Mg-Y-Zn-based alloys with fourth elements (nickel and calcium) have been investigated. The microalloying of 0.5 mass% calcium markedly increases the stacking fault density in the Mg-3 mass%Y-0.5 mass%Zn alloy. Furthermore, the addition of calcium can decrease the size of stacking faults. On the other hand, in the nickel-added alloy, many precipitates were formed and the estimated stacking faults density decreased significantly. The creep strength of the Mg-Y-Zn-Ca alloy is higher than that of the base alloy (Mg-3 mass%Y-0.5 mass%Zn, WZ305). Transmission electron microscopic (TEM) observations revealed that many a-dislocations on the basal planes in the magnesium matrix are extended during creep deformation in Mg-Y-Zn-based alloys. There was significant consumption of solute atoms in the matrix and deterioration of creep strength in the Mg-Y-Zn-Ni alloy, because the formation of a large number of precipitates began before creep. On the other hand, both the low mobile dislocation density and the large separation width of extended a-dislocations were observed in the Mg-Y-Zn-Ca alloy, which exhibits excellent creep strength at 650 K under 20 MPa.

The as-cast microstructure of Mg-5Al-3Ca-xNd alloys consists of equiaxed α-Mg matrix, (Mg, Al) 2 Ca eutectic phase and Al-Nd rich intermetallic compounds. With the increase of Nd addition, α-Mg matrix morphology was changed from dendritic to equiaxed grains due to suppression of grain growth by formation of homogeneous intermetallic compounds containing Nd dispersed at grain boundary and α-Mg matrix. And the grain size of as-cast alloys was decreased as addition of Nd was increased. This eutectic phase of the extruded alloys was elongated to extrusion direction and size of this phase was redined comparing to that of as-cast alloys because of severe deformation during hot extrusion. Maximum yield and ultimate tensile strength value of the as-extruded alloys was 322 and 335 MPa at Mg-5Al-3Ca-2Nd alloy, respectively.

Microstructures and Vickers hardness have been investigated in hot-rolled Mg-3mass%Y based solid solution alloys containing microalloying elements (Ca, Ag, and Ni). Transmission electron micorscope (TEM) observations have revealed that the stacking faults on the (0001) magnesium matrix planes have been observed in Mg-Y-Zn based alloys and the stacking fault (SF) density depends on other additional microalloying elements. In single addition of Zn to the Mg-Y alloy, SF density increases with increasing Zn content and was saturated over 0.5 mass% addition. On the other hand, in simultaneous addition of Zn and Ca, SF density increases with increasing Ca content significantly. Many precipitates were observed in Ni and Ag added Mg-3Y-0.5Zn alloys and their SF densities were lower than Mg-3Y-0.5Zn. Vickers hardness increased by the simultaneous microalloying of Zn and Ca, while Ag showed a negative effect for hardness in Mg-3Y-0.5Zn (in mass%) ternary alloy. The dense SF density could act as obstacles to the dislocation motion so that SF density has positive relationship in the Vickers hardness.

The as-cast microstructure of Mg-5Al-3Ca-2Sm alloy consists of equiaxed α-Mg matrix, (Mg, Al)2Ca eutectic phase and Al-Sm rich intermetallic compounds. This eutectic phase of the extruded alloys was elongated to extrusion direction and size of this phase was finered compare to that of as-cast alloys because of severe deformation during hot extrusion. After hot extrusion, the average grain size of Mg-5Al-3Ca and Mg-5Al-3Ca-2Sm alloys was 4.8 *m and 3.8 *m, respectively. In load-unload hardness test, penetration depth was decreased with added Sm and after extrusion procedure because of grain size refining by addition Sm and large deformation. Hardness value of the alloys containing Sm was higher than that of Mg-5Al-3Ca alloy due to grain refining and formation Al-Sm rich intermetallic compound at gain boundary and α-Mg matrix. Maximum hardness value was obtained at the extruded Mg-5Al-3Ca-2Sm alloy at elevated temperatures.

In this study, the high temperature oxidation behavior of polycrystalline MoSi2 in a low-pressure atmosphere was investigated. Polycrystalline MoSi2 was produced by the spark plasma sintering process. Oxidation tests were carried out at 1500°C at either 10Torr or 760Torr in an Ar-20%O2 atmosphere. For both conditions, the weight change peaked at the initial oxidation stage, and then their weights gradually increased with increasing oxidation time. The sample weight became heavier in the ambient pressure than in the low-pressure, but the evaporation oxidation was not significant in the low-pressure condition. After the low-pressure oxidation tests, the formation of Mo5Si3 in the MoSi2 substrate was identified. The oxidation resistance of MoSi2 at 1500°C is discussed based on the obtained results.

In medaka, we found a C16orf35-like gene in the region within 1 Kbp 3' downstream of the psibeta end of the 36-Kbp embryonic globin gene cluster ((5')alpha0(3')-(3')beta1(5')-(5')alpha1(3')-(5')beta2(3')-(5')alpha2(3')-(3')alpha3(5')-(5')beta3(3')-(3')beta4(5')-(5')alpha4(3')-(3')psialpha(5')-(5')psibeta(3')). Intron 5 of the gene contained a region having NF-E2 binding sites located between GATA boxes. The region was homologous to human HS-40 in terms of the existence and structure of characteristic transcription-factor binding sites and was named Ol-HS-40. Injection of the fusion gene construct Ol-HS-40-alpha0(up-2)GFP, consisting of Ol-HS-40, a 5' upstream 200-bp minimum promoter for alpha0, and green fluorescent protein (GFP), showed that Ol-HS-40, as in human HS-40, had the ability to strongly enhance GFP expression in erythroid cells of embryos. Further analysis using transgenic technology revealed that Ol-HS-40 had the ability to change the type of the GFP expression from embryo-to-young fish to embryo-to-adult. In addition, the results suggest that Ol-HS-40, although its natural function remains unclear, has strong enhancer activity for the expression of not only the alpha-globin gene but also the beta-globin gene.