First record of avian Plasmodium DNA from mosquitoes collected in the Yaeyama Archipelago, southwestern border of Japan

We studied the prevalence of avian Plasmodium in 509 mosquitoes of 9 species collected from the Ishigaki and Iriomote islands in the Yaeyama Archipelago, located southwest from the mainland of Japan. Two identical avian Plasmodium lineages were detected from Culex (Culiciomyia) nigropunctatus. Detected lineages were phylogenetically classified into different clade to avian Plasmodium lineages from birds and mosquitoes in the mainland of Japan but identical to a lineage detected from a resident bird, White-breasted Waterken (Amaurornis phoenicurus). This is the first detection of avian Plasmodium DNA from mosquitoes in the Yaeyama Archipelago and suggested that resident birds might have been infected with an avian Plasmodium lineage specific to the studied area and C. nigropunctatus could be the candidate vector mosquito species.     

Free Radical Formation after Intensive Exercise in Thoroughbred Skeletal Muscles

Although high oxygen consumption in skeletal muscle may result in severe oxidative stress, there are no direct studies that have documented free radical production in horse muscles after intensive exercise. To find a new parameter indicating the muscle adaptation state for the training of Thoroughbred horses, we examined free radical formation in the muscle by using electron paramagnetic resonance (EPR). Ten male Thoroughbred horses received conventional training for 18 weeks. Before and after the training period, all horses performed an exhaustive incremental load exercise on a 6% incline treadmill. Muscle samples of the middle gluteal muscle were taken pre-exercise and 1 min, 1 hr, and 1 day after exercise. Muscle fiber type composition was also determined in the pre-exercise samples by immunohistochemical staining with monoclonal antibody to myosin heavy chain. We measured the free radical in the muscle homogenate using EPR at room temperature, and the amount was expressed as relative EPR signal intensity. There was a significant increase in Type IIA muscle fiber composition and a decrease in Type IIX fiber composition after the training period. Before the training period, the mean value of the relative EPR signal intensity showed a significant increase over the pre-exercise value at 1 min after the exercise and an incomplete recovery at 24 hr after the exercise. While no significant changes were found in the relative EPR signal intensity after the training period. There was a significant relationship between percentages of Type IIA fiber and change rates in EPR signal intensity at 1 min after exercise. The measurement of free radicals may be useful for determining the muscle adaptation state in the training of Thoroughbred horses.     

Modified atmosphere packaging of fresh produce with a biodegradable laminate of chitosan-cellulose and polycaprolactone

Use of a biodegradable laminate of a chitosan-cellulose and polycaprolactone as a film for modified atmosphere packaging (MAP) of fresh produce was tested. The temperature dependence of O₂, CO₂ and N₂ gas permeability coefficients for the biodegradable laminate was examined. The coefficients increased linearly with increasing temperature in the range 10–25 °C. The coefficients were validated by experiments on MAP with shredded lettuce and shredded cabbage. MAP systems with head lettuce, cut broccoli, whole broccoli, tomatoes, sweet corn and blueberries were designed using the gas permeability coefficients. The gas composition in each biodegradable package including the fresh produce was simulated to be close to the optimal composition. The biodegradable laminate was found suitable as a packaging material for storage of fresh produce.     

Three-dimensional structure of Hayabusa samples: origin and evolution of Itokawa regolith

Regolith particles on the asteroid Itokawa were recovered by the Hayabusa mission. Their three-dimensional (3D) structure and other properties, revealed by x-ray microtomography, provide information on regolith formation. Modal abundances of minerals, bulk density (3.4 grams per cubic centimeter), and the 3D textures indicate that the particles represent a mixture of equilibrated and less-equilibrated LL chondrite materials. Evidence for melting was not seen on any of the particles. Some particles have rounded edges. Overall, the particles' size and shape are different from those seen in particles from the lunar regolith. These features suggest that meteoroid impacts on the asteroid surface primarily form much of the regolith particle, and that seismic-induced grain motion in the smooth terrain abrades them over time.     

Effects of acclimation on chilling tolerance in Asian cultivated and wild rice

Tolerance to low temperature can be enhanced by pre-exposure to low, non-harmful temperatures, a process known as acclimation. The effects of acclimation on chilling tolerance in species from tropical and subtropical regions are not well understood. Therefore, we investigated whether acclimation improved chilling tolerance at the plumule and seedling stages in Asian rice. A comparison of the effect of acclimation between chilling tolerance scores from a tolerant (A58) and a susceptible (W107) strain demonstrated that acclimation enhances chilling tolerance especially in the tolerant strain, indicating that considerable genetic variation in acclimation capacity exists. The genetic variation in chilling tolerance in acclimated plants was investigated using 57 strains derived from cultivated (Oryza sativa L. ssp. japonica and ssp. indica) and wild (O. rufipogon Griff.) rice. The genetic differentiation of the japonica and indica subspecies of cultivated rice with regard to chilling tolerance was more prominent in the presence than in the absence of acclimation. Furthermore, latitudinal clines for chilling tolerance were observed in both acclimated plumules and seedlings of wild rice, whereas without acclimation, a latitudinal cline was observed only at the plumule stage. This suggests that acclimation capacity, as well as intrinsic chilling tolerance, might contribute to local adaptation. QTLs involved in acclimated chilling tolerance at the plumule stage are different from those involved in intrinsic chilling tolerance. The present results indicate that the maximum genetic potential for chilling tolerance is achieved by acclimation, giving cautions for evaluation of genetic resources in rice.     

Neurotoxin Production by a Chloromonad Fibrocapsa japonica (Raphidophyceae)

The ichthyotoxicity and toxin composition of a red-tide producing chloromonad Fibrocapsa japonica (Toriumi and Takano) were examined. The flagellate showed the highest toxicity in mid-logarithmic phase and the lowest in the stationary phase with increased number of spherical-shaped cells. Five neurotoxic components, FjTx-I, FjTx-II, FjTx-IIIa, FjTx-IIIb and FjTx-IV, which corresponded to brevetoxin components, PbTx-1, PbTx-2, PbTx-9, PbTx-3 and oxidized PbTx-2 were tentatively identified from analysis of F. japonica toxins on TLC and HPLC. The quantity of each component fluctuated with the age and growth stage of the culture. Among the five toxic components the yield of FjTx-II per cell was highest in both logarithmic and stationary phases.     

应用TM卫星像片进行树种分布解析的研究

本文论述了ＴＭ卫星像片的图像处理技术，以日本北海道苫小牧地区森林为例，进行不同树种的计算机自动分类，并给出多光谱图像上不同年龄树种的灰度与年龄之间的相关图。研究结果表明：云杉属、冷杉、落叶松的反射率随年龄增大而降低，用最大似然法监督分类，可以很好地区分不同树种，得出苫小牧地区森林分布情况的遥感图像。     

Effects of slope and canopy trees on light conditions and biomass of dwarf bamboo under a coppice canopy

Dwarf bamboo, Pleioblastus chino, grows extensively in abandoned coppice woodlands on the Kanto Plain in central Japan and suppresses other understory plants. In order to clarify the factors determining the growth of P. chino, we considered the effect of light conditions under a coppice canopy and examined its relationship with slope aspect, slope angle, and basal area of the trees. The relative photon flux density under the canopy was highly correlated with canopy coverage (R ² = 0.97). The light conditions under the canopy were almost the same at all sites in the summer leafy season regardless of the stand type, while they were remarkably different among the sites and depended on the basal area of evergreen trees in the winter leafless season. The biomass of P. chino on the forest floor was described by the equation: y = 3.18 x ₁ – 0.05 x ₂ + 3.11 (R ² = 0.77, P < 0.01), where y is the log-transformed value of P. chino biomass (gdrymassm^–2), x ₁ is cos at solar noon at the winter solstice, and x ₂ is the canopy coverage during the winter leafless season. is the angle between the suns rays and the normal to the surface and changes with slope aspect and angle. We concluded that light conditions under the canopy in the leafless season had a great effect on P. chino biomass, and that the basal area of evergreen trees and slope characteristics can provide useful guidelines in the control and management of P. chino.     

Recessive inheritance of morphological characteristics of utsukushimatsu,<Emphasis Type="Italic">Pinus densiflora</Emphasis> f.<Emphasis Type="Italic">umbraculifera</Emphasis>

Pinus densiflora f.umbraculifera, commonly known as utsukushimatsu, is a distinctively shaped form of Japanese red pine whose growth is restricted to a forest stand in Shiga Prefecture, Japan. The inheritance mode of morphological characteristics of utsukushimatsu was studied to preserve the genetic resource of this pine. As previously reported, F₁ trees grown from open-pollinated seeds harvested from trees inhabiting the native stand showed two phenotypes: one resembling utsukushimatsu, which produces multiple trunks, and the other resembling normalP. densiflora, which produces one or a few trunks. In the present study, controlled pollination was carried out using F₁ and normalP. densiflora trees. Segregation ratios of the two phenotypes observed in the F₂ population showed that the morphological characteristics of utsukushimatsu are inherited recessively. This suggests that the mutation of one gene or a few closely linked genes controls the morphological characteristics of utsukushimatsu. Since multiple trunk formation of utsukushimatsu might be related to a loss of lateral bud inhibition, it follows that a simple gene mutation breaks apical dominance inP. densiflora.