不同含水量下工具材料切向土壤黏附特性（摘选）

为了提高越野车辆性能和建筑、农业领域机械工作效率,就需要了解土壤黏附机理。该试验旨在找到不同工具材料的土壤切向黏附与含水率之间的关系,探讨土壤切向黏附对土壤剪切力学性能的影响。试验对橡胶（RUB）、钢（SS400）和树脂（PEEK）3种材料进行了直剪试验。结果表明,土壤和材料之间的切向黏附随着土壤含水量的增加而增加至最大值后降低。土壤切向黏附最大值的排序是钢（SS400）,其次是橡胶（RUB）,最后是树脂（PEEK）。结果还表明,3种材料道具与测试土壤间的外摩擦角随着土壤含水率的增加先降低后增加,当发生剪切的时候,随着剪切的发生,土壤含水量导致切向黏附的变化进而直接影响剪切应力和外摩擦角。      

Wireless monitoring of blood glucose levels in flatfish with a needle biosensor

A wireless biosensor system was developed for the continuous measurement of blood glucose levels in flatfish. The biosensor was implanted in the interstitial fluid under the scleral surface of the eyeball (EISF) to investigate the relationship between EISF and blood glucose levels. EISF glucose levels were found to be correlated with those in the blood and to be approximately the same as blood glucose levels in the range of 7–25 mg dl⁻¹. A needle-type biosensor was prepared for the continuous EISF glucose monitoring in flatfish. A working electrode was constructed using platinum iridium wire, and glucose oxidase was immobilized to the electrode. The biosensor was inserted into the EISF of flatfish for sensor implantation. A 650-mV potential (vs. Ag/AgCl) was applied by a wireless potentiostat to the working electrode for the amperometric glucose measurement. We investigated whether glucose in the EISF can be determined in vivo. The estimated glucose levels using a one-point calibration method were correlated with actual blood glucose levels. In conclusion, using a wireless biosensor system, we were able to monitor blood glucose levels in flatfish under free-swimming conditions for 16 h.     

EMG telemetry studies on upstream migration of chum salmon in the Toyohira river,Hokkaido, Japan

The movements of 28 adult chum salmon, Oncorhynchus keta (Walbaum) tagged with electromyogram (EMG) transmitters were tracked along the Toyohira river, Hokkaido, Japan, in October of 2007 and 2008 to investigate and evaluate the upstream migratory behavior through the protection bed and fishway of ground sills. The approach time of fish that ascended successfully through the protection bed and fishway was shorter than that of unsuccessful fish. The unsuccessful fish were observed to swim in currents with high water velocity and shallow water depth at swimming speeds that exceeded their critical swimming speed (U _crit) during the approach to these structures. In consequence, unsuccessful fish frequently alternated between burst and maximum sustained speeds without ever ascending the fishway, and eventually became exhausted. It is important that fishway are constructed to enable chum salmon to find a passage way easily, so that they can migrate upstream rapidly without wasting excessive energy.     

Identification of oyster-derived hypotensive peptide acting as angiotensin-I-converting enzyme inhibitor

Angiotensin-I-converting enzyme (ACE) plays a crucial role in the crisis of hypertension. Some peptides that originate from protease hydrolysates are known to suppress ACE activity in vitro and in vivo. Here, we investigated whether trypsin hydrolysate of oyster Crassostrea gigas showed hypotensive activity and ACE inhibition. The hydrolysate significantly suppressed systolic blood pressure and ACE activity in spontaneously hypertensive rats following a one-shot oral administration and a long-term feeding experiment lasting 9 weeks. Each hydrolysate from oyster tissue showed ACE inhibitory activity, indicating the hypotensive effect was due to synergism. One potent ACE inhibitory peptide, Asp-Leu-Thr-Asp-Tyr, was identified from the hydrolysate of the striate muscle, and the peptide exhibited hypotensive activity in vivo. Protease digestion analysis suggested that Asp-Tyr could be the real effector of this penta-peptide in vivo.     

Habitat differentiation between sei (Balaenoptera borealis) and Bryde's whales (B. brydei) in the western North Pacific

Two closely related baleen whale species, sei and Bryde's whales, in the western North Pacific were studied to identify differences in habitat use. Data were obtained from May to August 2004 and 2005. This study examined the relationship between oceanographic features derived from satellite data and the distribution of sei and Bryde's whales using basic statistics. We investigated oceanographic features including sea surface temperature (SST), sea surface chlorophyll a (Chl‐a), sea surface height anomalies (SSHAs), and depth of the habitat. These two whale species used habitats with different SST, Chl‐a, and SSHA ranges. The 0.25 mg m^?3 Chl‐a contour (similar to the definition of the Transition Zone Chlorophyll Front) was a good indicator that separated the habitats of sei and Bryde's whales. Then generalized linear models were used to model the probabilities that the whale species would be present in a habitat and to estimate their habitat distribution throughout the study area as a function of environmental variables. The potential habitats of the two species were clearly divided, and the boundary moved north with seasonal progression. The habitat partitioning results indicated that SST contributed to the patterns of habitat‐use and might reflect differences in prey species between the two whales. This study showed that the habitats of the sei and Bryde's whales were clearly divided and their potential habitat‐use changed seasonally.     

Tracking the Northern Pacific sea star <Emphasis Type="Italic">Asterias amurensis</Emphasis> with acoustic transmitters in the scallop mariculture field of Hokkaido,Japan

The Northern Pacific sea star Asterias amurensis has a major negative impact on scallop mariculture. In northern Japan, fishermen clean up sea stars before releasing young scallops in the mariculture field; however, new sea stars constantly invade the field from outside areas to feed on scallops. Thus, it is important to determine the migration speed and seasonal behavioral patterns of the Northern Pacific sea star to implement effective density control measures. Here, we set out to quantify these parameters using acoustic telemetry. In a rearing experiment, acoustic transmitters were retained on sea stars for up to 71 days using nylon fishing line. In the field experiment, we showed that the moving distance of the Northern Pacific sea star over a 1-week period was significantly further in spring (90.9 ± 49.9 m) than in summer (25.1 ± 18.9 m), and that the moving speed was significantly faster in spring (18.1 ± 15.2 m/day) than in summer (4.3 ± 9.1 m/day). Our results are the first to present the two-dimensional movement of Northern Pacific sea star individuals in spring and summer. We suggest that sea star extermination practices should be extended beyond the immediate culture area.     

Thermal tolerance of a thermally selected strain of rainbow trout <Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis> and the pedigrees of its F1 and F2 generations indicated by their critical thermal maxima

A thermally selected strain of rainbow trout has been established by selective breeding since 1966 in Miyazaki, Japan. In the present study, we compared the critical thermal maxima (CTMs), the temperatures at which organisms reach a predefined sublethal endpoint and lose their equilibrium, between a thermally selected and two normal (Donaldson) strains of rainbow trout. The CTM of one normal strain from Nikko (Nikko strain) acclimated to 20 °C (29.7 °C) was significantly lower than those of the thermally selected strain (30.0 °C) and the other Donaldson strain from Aomori (29.9 °C) (P?<?0.05). The F1 generations, F1T and F1N, were produced by crossing thermally selected strain females with Nikko strain males and Nikko strain females with thermally selected strain males, respectively. No significant difference was observed in the CTM between F1T [30.1?±?0.15 °C (n?=?30)] and F1N [30.1?±?0.16 °C (n?=?30)] (P?>?0.05) for fish acclimated to 20 °C, suggesting that the F1 offspring inherited the thermal tolerance trait from one thermally selected strain parent irrespective of whether it was the male or female. F2 offspring of F1T or F1N also showed the thermal tolerance trait. The coefficients of variation for CTM were also compared among all the datasets obtained in the present study and their values for F1 hybrids were lower than those of the parental generation of the Nikko strain (P?<?0.05). In contrast, the coefficients of variation of F2s were the same as those of their parental generation. Furthermore, the thermally selected strain and Nikko strain as a reference family provide a F2 generation for segregating phenotypes, which is required for in-depth genetic analysis of the thermally selected rainbow trout strain.     

Influence of dietary fat level and whole-body adiposity on voluntary energy intake by juvenile rainbow trout Oncorhynchus mykiss (Walbaum) under self-feeding conditions

The influence of dietary fat level and whole‐body adiposity on voluntary energy intake of juvenile rainbow trout Oncorhynchus mykiss (Walbaum) was examined using self‐feeders. Groups of lean fish [crude fat (CF) = 7%] and fat fish (CF = 11%), pretreated with a commercial diet with or without supplemental pollock oil, were self‐fed one of three fat level diets (CF = 8%, 13.5% and 19%) for 48 days at 17 °C. Final body weight (BW) and total digestible energy (DE) intake (kJ per fish) were positively affected by the initial BW. Relative to the initial BW, however, fat fish consumed less DE than lean fish. Although the effect of dietary fat level was not significant, percentage weight gain and daily DE intake per BW (kJ kg^?1 BW day^?1) of fat fish were significantly lower than those of lean fish (ancova with initial BW as a covariate, P < 0.05). Energy digestibility, feed efficiency and protein retention were improved with the dietary fat level; however, there was no difference resulting from body fat level. The whole‐body fat levels at the end of the experiment increased with the dietary fat level. Between groups self‐fed the same diet, fat levels of the initially fat fish were still higher than those of the lean fish. The results of the present medium‐term study suggest that rainbow trout adjust DE intake from diets with fat levels ranging from 8% to 19%. Although body fat level affects neither energy digestibility nor protein utilization, a high body fat level may reduce DE intake and consequently depress growth.     

Proventricular dilatation disease associated with avian bornavirus infection in a Citron-crested Cockatoo that was born and hand-reared in Japan

A 5-month-old female Citron-crested Cockatoo (Cacatua sulphurea citrinocristata) that was born and hand-reared in Japan died with suspected proventricular dilatation disease (PDD). Macroscopic and microscopic examinations of the bird revealed characteristic features of PDD, i.e., distention of the proventriculus and infiltration of lymphocytes and plasma cells in ganglia of various organs and in central and peripheral nerves. A linkage of this PDD case to infection with avian bornavirus (ABV) was documented by RT-PCR amplification of the virus genomes from the affected bird. Phylogenetic analysis revealed that the ABV identified in this study clustered into the genotype 2, which is one of the dominant ABV genotypes worldwide. To the best of our knowledge, this is the first report of a natural case of PDD associated with ABV infection in Japan.