Susceptibilities of some aquatic ferns to paddy herbicide bensulfuron methyl

Paddy herbicides have the potential to cause adverse effects on non-target plants. Susceptibilities of some aquatic ferns ( Azolla japonica Franch. et Savat., Isoetes japonica A. Braun, Marsilea quadrifolia L. and Salvinia natans All.) and duckweeds ( Lemna minor L. and Spirodela polyrhiza Schleid.) to paddy herbicide bensulfuron methyl (BSM) were evaluated with a 20 day exposure experiment using 200 cm² pots. The BSM concentrations in the surface water of monitoring pots with no plants dissipated exponentially with half lives of 3.5 and 3.9 days at application rates of 15 and 150 g ha⁻¹, respectively. The BSM concentrations in the surface water 1 day after application in the culture pots were comparable among plant species, and were lower than those in the monitoring pots. Bensulfuron methyl reduced the plant growth in all species. I . japonica showed the lowest intrinsic relative growth rate (RGR) and the lowest susceptibility with an effective dose resulting in 50% growth inhibition (ED₅₀) of 21 g ha⁻¹. Except for I . japonica , the RGR of the duckweeds was similar to the ferns, and ED₅₀ for the duckweeds was higher than the ferns. ED₅₀ for Sa . natans , A . japonica and M . quadrifolia were 1.1, 1.8 and 1.2 g ha⁻¹, respectively, which were smaller than 1/20 of the recommended field dose (51–75 g ha⁻¹) and ranged from 1/2 to 1/6 of ED₅₀ for L . minor and Sp . polyrhiza (6.5 and 3.2 g ha⁻¹, respectively). These results suggest that BSM application in paddy fields and its runoff in some localities is expected to have adverse effects on the growth of Sa . natans , A . japonica and M . quadrifolia .     

Evidence of homing of black rockfish Sebastes inermis using biotelemetry

ABSTRACT: The black rockfish Sebastes inermis is one of the most important fishery species along the coast from southern Hokkaido to Kyushu, Japan and is often found in rocks and Zostera areas. We conducted biotelemetry using coded ultrasonic transmitters to clarify the movement of the black rockfish that inhabited the seawall of the Kansai International Airport. We released 25 black rockfish at two points. One was the airport seawall and the other was side shallows off the Sensyu district. Seventeen black rockfish returned to their capture site after release. We used the V -test to determine whether the direction of movement was random or orientated. The black rockfish moved at random along the seawall within some hours after release ( P  > 0.05). Four hours after release, they moved to their home site intentionally ( P  < 0.0025).     

OSTEORADIONECROSIS AND RADIATION INDUCED BONE TUMORS FOLLOWING ORTHOVOLTAGE RADIATION THERAPY IN DOGS

Osteoradionecrosis and radiation-induced bone tumors are rare complications of radiation therapy. Little information regarding these complications is available in veterinary medicine. We characterized these complications and investigated risk factors in 119 dogs (122 sites) that received definitive orthovoltage radiation therapy to appendicular sites. Long-term survival was expected in all dogs. The complications of interest were osteoradionecrosis and secondary bone tumor, evaluated radiographically, histopathologically, or both. Complication rates were estimated using the Kaplan–Meier product-limit method, and Fisher's exact test or chi-square test was used to compare the complication rate. The median survival time was 1405 days, with median follow-up duration of 657 days. There were 10 radiation-induced bone tumors and five radiation-induced fractures, with two dogs developing both, for an overall complication rate of 11%. The latent period ranged from 1.2 to 6.4 years for osteoradionecrosis and from 2.6 to 8.7 years for radiation-induced bone tumor. Complications were significantly higher in the humerus ( P <0.0001), and in dogs younger than 7 years ( P =0.014). Similar assessment of complications in dogs irradiated with megavoltage photons or electrons are needed.     

Acoustic identification of isada krill, Euphausia pacifica Hansen, off the Sanriku coast, north-eastern Japan

In this study, the feasibility of identification and abundance estimation of isada krill, Euphausia pacifica , was examined using a two-frequency (38 and 120 kHz) method. The acoustic survey and midwater trawling were conducted off the Sanriku coast, northern part of Honshu, Japan. In one pattern, the SV difference between the two frequencies was large, and in the other, the SV difference was small. These results were interpreted by scattering models, and showed that discrimination between isada krill and walleye pollock was possible.     

Effects of salt stress on ion accumulation and antioxidative enzyme activities of Oryza sativa L. and Echinochloa oryzicola Vasing

The effects of salt stress on physiological factors, such as inorganic ion absorption and antioxidative enzyme activities, of rice ( Oryza sativa L. cv. Anapurna) and Echinochloa oryzicola Vasing were investigated. Although having similar morphology, rice and E. oryzicola possessed considerably different salt-tolerance mechanisms. Echinochloa oryzicola was more salt-tolerant than rice. When exposed to salt stress (100 mmol L⁻¹ sodium chloride, NaCl; six days), E. oryzicola had the ability to limit the accumulation of sodium ions (Na⁺), maintained high potassium ion (K⁺) content and had a constantly higher K⁺/Na⁺ ratio than rice. Rice was not effective in limiting Na⁺ absorption but had a higher antioxidative capacity than E. oryzicola . The constitutive activities of superoxide dismutase (SOD) and catalase of rice were three and five times higher than that of E. oryzicola, respectively. Induced activities of SOD, ascorbate peroxidase and glutathione reductase were also higher in rice than in E. oryzicola . The high antioxidative capacity was one of the tolerance mechanisms used by rice to cope with salt stress. Therefore, the salt tolerant-mechanisms are different between the two plants.     

Gustatory receptor responses in marbled rockfish Sebastiscus marmoratus

Gustatory response of marbled rockfish Sebastiscus marmoratus was recorded from the facial nerve supplying the anterior palate. In amino acids, the lowest threshold was for L -proline at 10⁻⁶–10⁻⁵ M; in ATP-related substances, the value for inosine was approximately 10⁻⁵ M and in organic acids, the value for L -lactic acid was approximately 10⁻⁶ M. An almost complete self-adaptation was observed for stimulants after 5 s application. While a weak solution of L -lactic acid as adapting stimulus depressed the response to it completely, it did not appreciably affect the response to 10-times or more concentrated L -lactic acid solution. In contrast to a weak solution, a moderate solution caused a severe depression of the response to stronger solutions, resulting in a shift of the dose–response curve towards a high concentration range. Time for recovery from adaptation differed depending on chemicals and stimulus duration: for 10⁻⁴ M L -lactic acid, it took about 2.3 and 4.5 s for 1/2 recovery of response magnitude under unadapted condition from the adaptation after 1 s- and 5 s-stimulation, respectively. L -Lactic acid and L -alanine strongly depressed the response to each other, yielding a rightward shift of the dose–response curve. A similar profound cross-adaptation was also observed between inosine and 5'-inosinic acid. The possible role of gustation is discussed.     

Thermal resistance traits of the clonal silver crucian carp Carassius langsdorfii and evaluation of these traits using primary culture cells

The thermal resistance traits of three clonal lines of the silver crucian carp Carassius langsdorfii (SCC-1, -2 and -3) were investigated. Individual juvenile fish reared at 20°C were exposed to thermal stress at 36.5 ± 0.5°C and their death times during this exposure were measured. The death times of SCC-2 and SCC-3 fish were 66.6 ± 31.2 and 144.7 ± 49.8 min, respectively. In contrast, all SCC-1 fish survived under these conditions. Furthermore, the thermal sensitivity of primary culture cells from each clone was determined at 37, 40 or 43°C by the Trypan blue assay. Under all treatment conditions, the thermal sensitivity of the SCC-1 primary cultures was lower than those of the others. These results estimated the correlation between the in vivo and in vitro thermal resistances. Therefore, the use of primary culture cells to evaluate thermal resistance could be a useful method of selection breeding.