Measurements of auditory sensitivity in common carp <Emphasis Type="Italic">Cyprinus carpio</Emphasis> by the auditory brainstem response technique and cardiac conditioning method

ABSTRACT:   Recently, the non-invasive auditory brainstem response (ABR) technique has been applied to the determination of hearing sensitivity in fish. The technique has some advantages over, and methodological differences from, the classical techniques. The auditory thresholds of common carp were measured by the ABR technique. The classical method was applied to measure cardiac response by electrocardiogram (ECG) after conditioning with electric shock. The most sensitive frequency obtained by ABR was 505 Hz, and by ECG, 1000 Hz. The shapes of the audiogram obtained by ABR and ECG were similar, though threshold levels in both audiograms differed from each other. Furthermore, audiograms obtained by using behavioral techniques were compared with those taken by the ABR and ECG techniques to assess the validity of the ABR technique for testing fish hearing sensitivity. The measured threshold levels increased in the order of behavioral, ABR, and ECG techniques, in the range below 1000 Hz.     

Underwater sound detection by cephalopod statocyst

Abstract:   The cephalopod receptor of particle motion was identified. In a previous study, it was suggested that statocysts served this function, but there was no direct supporting evidence, and epidermal hair cells had not been conclusively ruled out. Experiments on Octopus ocellatus were conducted using respiratory activity as an indicator of sound perception. Intact animals clearly responded to 141-Hz particle motion at particle accelerations below 1.3 × 10⁻³ m/s², and the mean perception threshold at this frequency was approximately 6.0 × 10⁻⁴ m/s². Specimens in which the statoliths had been surgically removed did not show any response for accelerations up to 3.9 × 10⁻³ m/s² at 141 Hz, which was approximately 16 dB greater than the mean perception threshold at this frequency. Specimens that had undergone a control operation in which the statoliths remained intact showed positive responses at 2.8 × 10⁻³ m/s² for the same frequency stimulus. This indicates that the statocyst, which is morphologically similar to the inner ear system in fish, is responsible for the observed responses to particle motion in O. ocellatus . This is the first direct evidence that cephalopods detect kinetic sound components using statocysts.     

Ammonia Emission from a Young Larch Ecosystem Afforested after Clear-Cutting of a Pristine Forest in Northernmost Japan

The present study aimed to elucidate the atmosphere–forest exchange of ammoniacal nitrogen (NH_X-N) at a young larch ecosystem. NH_X-N exchanges were measured at a remote site in northernmost Japan where 4-year-old larches were growing after a pristine forest had been clear-cut and subsequent dense dwarf bamboo (Sasa) had been strip-cut. The site was a clean area for atmospheric ammonia with mean concentrations of 0.38 and 0.11 μg N m^?3 in snowless and snow seasons, respectively. However, there was a general net emission of NH_X-N. The annual estimated emission of NH_X-N of 4.8 kg N ha^?1 year^?1 exceeded the annual wet deposition of 2.4 kg N ha^?1 year^?1, but the weekly exchange fluxes may have been underestimated by 28–60%. The main cause of the ammonia loss from the young larch ecosystem was probably enhanced nitrogen supply stimulated by the cutting of the pristine forest and Sasa, in particular, the Sasa.     

Changes of serum 3-methylhistidine concentration and energy-associated metabolites in dairy cows with ketosis

The present study examined the Serum 3-methylhistidine concentrations and energy-associated variables of 5 healthy Holstein cows and 5 Holstein cows with ketosis. The serum total cholesterol and apolipoprotein B-100 concentrations and lecithin-cholesterol acyltransferase (LCAT) activity of the ketotic cows were lower than those of the healthy cows 14 days before parturition. The serum non-esterified fatty acid (NEFA) concentration on the day of parturition and 3-methylhistidine concentration 14 days after parturition were higher in the ketotic cows. The serum 3-methylhistidine concentration 14 days after parturition was negatively correlated with the serum LCAT activity 14 days before parturition and was positively correlated with the serum NEFA concentration on the day of parturition. Insufficiency of cholesterol metabolism and acceleration of body fat degradation occur before parturition in cows with ketosis, and these characteristics are correlated with acceleration of protein degradation after parturition.     

Pathogenic races of soybean rust Phakopsora pachyrhizi collected in Tsukuba and vicinity in Ibaraki,Japan

Six races were identified among 26 single-lesion isolates of Phakopsora pachyrhizi from rust-infected leaves of nine samples of cultivated soybean and one sample of the wild host plant kudzu (Pueraria lobata) collected in Tsukuba and vicinity in Ibaraki, Central Honshu, Japan. Six races were detected on soybean cultivars and four races on kudzu. When two or more isolates obtained from the same samples were examined, the isolates were different races except from two samples. These results indicate that two or more races may be distributed on the same soybean cultivar and that the same races share soybean and kudzu hosts.     

Geographic variations in the whistles among three Indo-Pacific bottlenose dolphin <Emphasis Type="Italic">Tursiops aduncus</Emphasis> populations in Japan

ABSTRACT:   Whistles of Indo-Pacific bottlenose dolphins from three populations in Japan were collected and analyzed quantitatively. Geographic variations in the whistles among populations were found. Significant differences in the whistles among years within each population were also found, but those differences could not explain whole differences among populations because some parameters of the whistles had more differences among populations than among years within each population. As changes with time in the whistles within each population might cause the geographic variations among populations, researchers should take the yearly change within populations into consideration when they study the geographic variation in the whistle of dolphins.     

Reutilization of culture wastes ofPleurotus ostreatus andPhollota nameko for cultivation ofLyophyllum decastes

Possible reutilization of fresh and aged culture wastes of mushrooms for cultivatingLyophyllum decastes was investigated, although bark compost has commonly been used as a substrate for cultivating this fungus. The culture wastes studied were obtained after harvestingPleurotus ostreatus andPholiota nameko mushrooms. Mycelia ofL. decastes grew in the media containing both the fresh culture waste ofP. nameko and bark compost. However, it did not grow in the medium containing only the fresh culture waste ofP. nameko or in any media containing the fresh culture waste ofP. ostreatus. The mycelial growth inhibition in the fresh culture wastes ofP. ostreatus might be caused by the water-soluble inhibitors present. Mycelia ofL. decastes grew in all the media with aged culture wastes of bothP. ostreatus andP. nameko, which had been left outdoors for 6 months, regardless of whether bark compost was mixed. Fruit bodies were produced on all the tested media with aged culture wastes of both mushrooms, which had been left outdoors for a year. The aged culture waste ofP. nameko gave greater yields than the bark compost. This investigation shows that the aged culture wastes ofP. ostreatus andP. nameko could be reutilized for producingL. decastes mushrooms.This study was presented in part at the 47th annual meeting of Japan Wood Research Society, Kochi, April 1997