Carbon nanotube enhanced label-free immunosensor for amperometric determination of oocyte maturation-inducing hormone in fish

Maintaining high-quality fish eggs stably and efficiently is important for aquaculture. We developed a label-free immunosensor system for measuring 17,20β-dihydroxy-4-pregnen-3-one (DHP). DHP is suddenly secreted before ovulation as a maturation-inducing hormone in fish, and therefore, DHP levels are an indicator for predicting ovulation. The method is based on immunologic reactions and amperometric measurement using cyclic voltammetry (CV). For biomolecular immobilization on the surface of sensing electrode, Au electrode, we used self-assembled monolayers of thiol-containing compounds to fix anti-DHP immunoglobulin. In addition, we used a single-walled carbon nanotube to improve sensitivity. Using this electrode, we were able to determine the CV signal change caused by the antigen–antibody complex. The proposed immunosensor system showed a linear correlation (correlation coefficient: 0.9827) between the anodic peak current of the CV and the DHP level in range from 15.6 to 50,000 pg ml^?1. The sensor system was then applied to monitor DHP of goldfish (Carassius auratus). Blood plasma of fish was collected every 3 h after administering a DHP inducer. In the measurement, the anodic peak current of the CV showed distinct changes depending on DHP levels in the blood plasma. A good relationship was observed between DHP levels determined by our proposed system and the conventional method (correlation coefficient: 0.9351).     

Ultra highly sensitive method for detecting Flavobacterium psychrophilum using high‐gradient immunomagnetic separation with a polymerase chain reaction

We attempted to develop an ultrahigh sensitive method for detecting Flavobacterium psychrophilum using high‐gradient immunomagnetic separation (HGIMS) with a polymerase chain reaction (PCR). HGIMS is a magnetic separation method in which the magnetic force is strengthened by introducing a magnetic gradient between the magnetic filter and nearby column. Because immunomagnetic beads specifically react with target cells, target cells are collected efficiently. Accumulated beads are released from the filter by removing the external magnetic force. After concentrating the samples using the HGIMS system, DNA was extracted from the samples, and PCR was applied to detect F. psychrophilum. Our primers did not react with reference bacteria and reacted specifically with F. psychrophilum. The detection sensitivity using the HGIMS system was higher than that of the method without the HGIMS system, and the total assay time, including sample preparation, was <3.5 h. PCR products of the expected size were obtained from samples of concentrated 4 × 10^?1 to 4 × 10³ cfu mL^?1F. psychrophilum more than 80% of the time using the HGIMS system. Furthermore, our proposed method could be useful for the specific detection of F. psychrophilum from actual samples. Our proposed method is suitable for the highly sensitive detection of F. psychrophilum.     

Feeding events of Japanese lates <Emphasis Type="Italic">Lates japonicus</Emphasis> detected by a high-speed video camera and three-axis micro-acceleration data-logger

The feeding events of wild animals have been widely researched in recent decades. The use of invasive methods to determine stomach contents in which the fish is killed can, however, be considered to be unjustifiable in the case of an endangered fish, such as the Japanese late. Here, we report on a method that can be used to verify feeding events of a fish species without the need for killing the fish through the use of a high-speed video camera and a three-axis micro-acceleration data-logger. High-quality images obtained by the video showed that the fish opens its mouth with a quick downward movement of the mandibles and ingests prey via suction feeding. The movement of the mandibles was also simultaneously recorded by changes in the three-axis accelerations obtained by the logger attached to the dorsum. We attached the logger with an automatic release system to the dorsum of one captive Japanese lates and two wild fish together with an acoustic transmitter and then released the fish in the Shimanto River in Japan. After retrieving the logger, the movement records of the fish obtained by the three-axis accelerometer showed the same pattern of feeding events as those in captivity. A total of 13 feeding events at night and five during the daytime were obtained for the three fish during a total 129.7 h of recording.     

Anti-oxidative, anti-tumor-promoting, and anti-carcinogensis activities of nitroastaxanthin and nitrolutein, the reaction products of astaxanthin and lutein with peroxynitrite

Astaxanthin captured peroxynitrite to form nitroastaxanthins. 15-Nitroastaxanthin was a major reaction product of astaxanthin with peroxynitrite. Here, the anti-oxidative, anti-tumor-promoting, and anti-carcinogensis activities of 15-nitroastaxanthin were investigated. In addition to astaxanthin, 15-nitroastaxanthin showed excellent singlet oxygen quenching activity. Furthermore, 15-nitroastaxanthin showed inhibitory effects of in vitro Epstein-Barr virus early antigen activation and two-stage carcinogensis on mouse skin papillomas. These activities were slightly higher than those of astaxanthin. Similar results were obtained for the 15-nitrolutein, a major reaction product of lutein with peroxynitrite.     

Simulation of the impact of climate change on the egg and larval transport of Japanese anchovy (Engraulis japonicus) off Kyushu Island,the western coast of Japan

In order to investigate the impact of climate change on egg and larval transport of Japanese anchovy (Engraulis japonicus) off Kyushu Island western Japan, we conducted particle‐tracking simulations on transport success/failure to fishing grounds from 1960 to 2007. The modeled transport success since the mid‐1990s increased and decreased in the offshore and coastal zones, respectively, compared with the 1960s and 1970s. The estimated northward shift of the spawning ground and weakened Tsushima Warm Current contributed to increase in modeled transport success to the offshore zone. Conversely, the weakening trend of the modeled onshore current in the Goto‐Nada Sea combined with the northward shift of the spawning ground resulted in unsuccessful larval transport. These results suggest that fluctuations in juvenile and subadult anchovy catches in this area may be attributable to changes in the physical environment. The present study showed that changes in transport success induced by oceanographic fluctuations related to climate change, have the potential to affect anchovy recruitment off the western coast of Japan.     

Development of an air-injection press for preventing blowout of particleboard (III): effects of pressing temperature on board performance

An air-injection press, which has holes punched in the heating plates, injects high-pressure air through the holes of one plate into particleboards and discharges the air and vapor through the other plate during press heating. The press can manufacture particleboards from high-moisture particles by preventing blowouts of the boards. In this study, the effects of pressing temperature were investigated by pressing boards at 190, 210, and 230°C. The internal bond strength increased from 0.43 to 0.60?MPa by raising the temperature from 190 to 210°C, but did not increase further when the temperature was raised to 230°C. Raising the temperature from 190 to 210°C also helped improve the thickness swelling. No relationship was found between the modulus of rupture and pressing temperature.     

Chemistry of the Urauchi River Water in Iriomote Island National Park, Okinawa, Japan

The chemical characteristics of the Urauchi River water in Iriomote Island National park, Okinawa, Japan have been studied. Concentrations of PO₄ ^3?, NO₂ ^?, and NH₄ ⁺ were barely detectable. We compared the concentration ratios of Mg²⁺/Na⁺, HCO₃ ^?/Na⁺, and Ca²⁺/Na⁺ in the Urauchi River to those of 60 large rivers in the world and indicated that the chemical composition of the river is most likely formed by the binary mixing of sea salt components and silicate rock weathering components. Although rock weathering in the catchments area is driven by both H₂CO₃ and H₂SO₄, the role of H₂CO₃ is dominant. The percentages of the concentration of each cation in the river water are almost the same as those of other rivers with drainage areas consisting of silicate rock and sandstone. Thus, the Urauchi River shows the typical chemical characteristics of a river in a silicate rock area that includes sandstone.     

Proteolytic digestive enzyme response in Japanese flounder larvae <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis> fed two types of rotifers <Emphasis Type="Italic">Brachionus plicatilis</Emphasis> species complex

Two common live feeds, the Brachionus plicatilis species complex SS-type and L-type were used to assess whether there were any differences in protein hydrolysis and digestive trypsin activity in first feeding Japanese flounder. There were no significant differences in hydrolysis activity at 2, 3 and 7 days after hatching (DAH). At 5 DAH, hydrolysis activity was significantly higher in larvae fed SS-type (p?<?0.05) at 50 kDa in 1.5- and 3-h incubation whereas L-type treatment had not completely hydrolyzed the proteins after 3 h at the same molecular weight. Larvae fed SS-type had significantly higher (p?<?0.05) trypsin activity at 3, 5, 6, 7 DAH. Contribution of live prey to trypsin fraction in larvae showed significantly higher (p?<?0.05) fraction for SS-type at 5 DAH (2.18?±?0.44%) and 6 DAH (2.04?±?0.29%) and the effect of exogenous trypsin from live prey was relatively low when compared to the total trypsin activity in larvae. This study discusses the differences in ability to digest proteins in Japanese flounder when fed different rotifer morphotypes and highlights the adaptability of this species to alternative rotifer morphotypes during its early developmental stages.     

Chronic cadmium treatment induces islet B cell injury in ovariectomized cynomolgus monkeys

In an attempt to establish a primate model of chronic cadmium (Cd) toxicosis, we ovariectomized cynomolgus monkeys and treated with CdCl2 by repeated intravenous injections for 13 to 15 months. The animals showed an increase in blood glucose from Month 10 and a decrease in blood insulin at Month 11of the Cd-treatment. Histopathological examination of the Cd-treated animals revealed islet atrophy with reduction in islet number and vacuolation of the islet cells, whereas there was no remarkable change in the acinar cells of the exocrine pancreas. In histomorphometrical examination, insulin-positive areas in the islets were significantly decreased, accompanying a relative increase of glucagon-positive areas. Large amounts of Cd accumulated in the pancreas, and metallothionein (MT), a Cd binding protein, was localized in the islets of Cd-treated animals. The present study demonstrated that the chronic intravenous injection of Cd to cynomolgus monkeys induced the accumulation of the metal in the pancreas, degeneration of islet B cells and the diabetic clinical signs. Therefore the islet B cell is one of the major targets of the chronic Cd poisoning in monkeys.     

Expression of mRNA for sodium-glucose transporter 1 and fatty acid translocase in the ruminant gastrointestinal tract before and after weaning

The mRNA expression of sodium‐glucose transporter 1 (SGLT1) and fatty acid translocase (CD36) in the gastrointestinal tract of Holstein cattle and Saanen goats before and after weaning was investigated. Before weaning, the expression of both SGLT1 and CD36 was highest in the jejunum, relative to the other parts of the gastrointestinal tract in both species. The expression of SGLT1 and CD36 in the duodenum was second highest in the goats. After weaning, SGLT1 and CD36 expression in the small intestine significantly decreased in both species. The expression of both types of transporters was also detected in the forestomach. From these results, it was concluded that the jejunum is probably the major absorption site for glucose and long‐chain fatty acids before weaning, and that the expression of both types of transporters decreases after weaning in cattle and goats.