Effect of water current on the body size and occurrence of deformities in reared Japanese eel leptocephali and glass eels     

Mari Kuroki  Akihiro Okamura  Aya Takeuchi  Katsumi Tsukamoto 《Fisheries Science》2016,82(6):941-951

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A resource selection model for analyzing pseudoreplicated data due to grouping behavior of animals     

Hiroshi Okamura  Masashi Kiyota  Toshihide Kitakado 《Journal of Agricultural, Biological & Environmental Statistics》2008,13(3):294-312

Quantifying resource selection is of primary interest in animal ecology. Many analyses of resource selection assume spatial and temporal independence of the sampling unit. Autocorrelation between observations, which is a general property of ecological variables, causes difficulties for most standard statistical procedures of resource selection because autocorrelated data violate the assumption of independence. To overcome this problem, we develop a mixed-effects model to estimate resource selection functions from data that are autocorrelated because of unobserved grouping behavior by animals. In the application of the expectation-maximization (EM) algorithm, the computation of the conditional expectation of the complete-data log-likelihood function does not have a closed-form solution requiring numerical integration. A Monte Carlo EM algorithm with Gibbs sampling can be used effectively in such situations to find exact maximum likelihood estimates. We propose a simple automated Monte Carlo EM algorithm with multiple sequences in which the Monte Carlo sample size is increased when the EM step is swamped by Monte Carlo errors.We demonstrate that the model can detect inherent autocorrelation and provide reasonable variance estimates when applied to nocturnal bird migration data. This approach could also be applied to ecological processes with various types of spatially and temporally autocorrelated data, circumventing serious problems caused by dangerous pseudoreplication.  相似文献   

Soft X-ray observation of water distribution in the stem ofCryptomeria japonica D. Don I: General description of water distribution     

Ryogo Nakada  Yoshitake Fujisawa  Yasuhiko Hirakawa 《Journal of Wood Science》1999,45(3):188-193

Water distribution in green stems ofCryptomeria japonica D. Don was observed by soft X-ray photography. In the sapwood, much water was present and evenly distributed. In the intermediate wood (the white zone), little water was present. The intermediate wood appeared in all cross sections of the stem and separated the heartwood from the sapwood in the intertracheid water connection. Maldistribution of water was generally observed in the heartwood, and three types of water presence were distinguishable: a “wet area” with accumulated water, a “dry area” with little water, and a “moderate moisture area” with intermediate accumulation. The distribution pattern and amount of water in the heartwood varied dramatically among and even within trees. Separation of the heartwood from the sapwood in the intertracheid water connection suggested that the presence of water in the heartwood was caused by rewetting of the tracheid lamina that occurred after heartwood formation. The maldistribution of water in the heartwood suggested that a difference in the process of rewetting causes both uneven distribution and the various types of water presence.  相似文献   

Growth and survival of eel leptocephali (Anguilla japonica) in low-salinity water     

Akihiro Okamura  Yoshiaki Yamada  Naomi Mikawa  Noriyuki Horie  Tomoko Utoh  Toyoji Kaneko  Satoru Tanaka  Katsumi Tsukamoto   《Aquaculture (Amsterdam, Netherlands)》2009,296(3-4):367-372

We investigated the effects of low-salinity water on the growth, survival, and activity of artificially reared Japanese eel larvae (Anguilla japonica), proceeding from the assumption that such water quality saves energy due to lower cost for osmoregulation. We reared 5-day-old larvae in 0%, 10%, 30%, 50%, 70%, and 100% seawater (SW) with or without diet for 13 days. All larvae reared in 0% and 10% SW died within 6 days, while larvae in 70% and 100% SW survived until 9 days. Larvae in 30% and 50% SW further survived until 13 days without diet. Significant growth in body depth was observed in 30% and 50% SW after 7 days rearing with diet (0.65 ± 0.02 and 0.62 ± 0.02 mm, respectively) as compared with the initial size (0.49 ± 0.03 mm), while no significant growth was observed under the other salinity conditions examined. Larvae swam actively in the light (about 2000 lx) in 50%, 70%, and 100% SW, while they were apparently inactive in 0%, 10%, and 30% SW. The long-term rearing trial showed a 2.2-fold higher 2-month cumulative survival rate in 50% SW (18.2%) than in 100% SW (8.2%). The body depth of larvae in 50% SW (1.58 ± 0.47 mm) was also significantly larger than in 100% SW (1.32 ± 0.35 mm). These findings indicate that the intermediate salinity can result in better growth and survival performance in Japanese eel larvae.  相似文献   

Participation of iron in denitrification in waterlogged soil     

Komatsu Yasuhiko  Takagi Masanosuke  Yamaguchi Masuro 《Soil biology & biochemistry》1978,10(1):21-26

A study was made of the formation of anaerobiosis in a waterlogged soil. A dilute soil suspension containing NO^?₃, Fe³⁺, sodium citrate, a limited amount of O₂, and trace elements was used as a model of waterlogged soil. Polarography was used to detect dissolved O₂, Fe³⁺ and Fe²⁺. The fates of the NO^?₃ and Fe³⁺ during and after O₂ consumption by the microorganisms were studied in a specially designed vessel. A close correspondence was obtained between the reduction of NO^?₃, NO^?₂ and Fe³⁺ and the growth of denitrifying bacteria in the closed system employed. From the experimental results we presume that microorganisms which respire NO^?₃ are also capable of utilising Fe³⁺ in their respiration. The mechanisms of reduction of these chemical species by the microorganisms are also discussed, emphasising the possibility of the participation of chemical reduction of NO^?₂ by Fe²⁺ in the over-all reduction process.  相似文献   

Toward sustainable management of small cetacean fisheries around Japan     

Hiroshi Okamura  Toshihide Iwasaki  Tomio Miyashita 《Fisheries Science》2008,74(4):718-729

Abstract:   The management of Japanese domestic fisheries for small cetaceans has been based on a traditional approach that involves only the best set of assumptions and data. However, uncertainty, which is pervasive and inevitable for most fisheries resources, often leads the traditional approach to serious failure. Here is presented the basic framework of a simulation-based approach with a simple Bayesian method that is applicable to Japanese fisheries for small cetaceans. For illustration, the simulation model was applied to Dall's porpoise data in order to investigate the robustness of several management procedures against uncertainty. The simulation showed that the current management procedure, based on only the best values, could fail to manage the stocks at a considerably high probability. However, the use of the conservative management procedure, potential biological removal, permits the sustainable harvesting of Dall's porpoise for at least 100 years into the future, even under uncertainty. In conjunction with a firm structure for implementation of management procedures, the spread of simulation-based approaches will quickly enable successful sustainable management of small cetaceans.  相似文献   

Reproduction of turbinate atrophy in pigs by intranasal consecutive-day inoculation with suspensions of a toxigenic serotype D strain of Pasteurella multocida.     

T Kawai  T Honda  Y Tokuyama  A Taneno  S Oishi  H Okamura  F Nonaka  E Sakai  T Miyahara  M Eto 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1991,53(3):507-509

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Metabolism of a phosphoramidate by Pyricularia oryzae in relation to tolerance and synergism by a phosphorothiolate and isoprothiolane     

Yasuhiko Uesugi  Hugh D. Sisler 《Pesticide biochemistry and physiology》1978,9(3):247-254

Metabolism of dibutyl N-methyl-N-phenylphosphoramidate (BPA) by mycelial cells of Pyricularia oryzae was studied to elucidate the mechanism of synergism and negatively correlated cross-resistance in fungicidal action between phosphoramidates and phosphorothiolate derivatives. Rapid metabolism of BPA by a wild-type strain through hydroxylation and N-demethylation was observed. The metabolism was inhibited by diisopropyl S-benzyl phosphorothiolate (IBP; Kitazin P) and by isoprothiolane (diisopropyl 1,3-dithiolan-2-ylidenemalonate; Fuji-One). This inhibition of BPA metabolism is probably the mechanism of synergistic fungicidal action between the phosphoramidate and the thiol derivatives. The metabolism was, however, not inhibited by S-1358 (S-butyl S′-p-tert-butylbenzyl N-3-pyridyldithiocarbonimidate; Denmert) or triarimol [α-(2,4-dichlorophenyl)-α-phenyl-5-pyrimidinemethanol; EL-273], both of which are considered to be inhibitors of hydroxylation of a methyl radical in ergosterol biosynthesis. The metabolism of BPA by P. oryzae was much slower when mutants selected for IBP resistance and for isoprothiolane resistance were used. This phenomenon probably explains the differential sensitivity to phosphoramidate of wild-type strains and mutants resistant to the thiol derivatives.  相似文献   

Puerperal and parental experiences alter rat preferences for pup odors via changes in the oxytocin system     

Arisa MUNETOMO  Hirotaka ISHII  Takenori MIYAMOTO  Yasuo SAKUMA  Yasuhiko KONDO 《The Journal of reproduction and development》2016,62(1):17-27

In the rat, induction of maternal behavior depends on the parity of the female. For example, nulliparous (NP) females need longer exposure to pups than multiparous (MP) or lactating (L) females to exhibit similar maternal behavior. In this study, we investigated the role of brain oxytocin in the approaching behavior of these female rats. Olfactory preferences for pup odors were examined for 8 consecutive days. Each preference test was followed by direct overnight exposure to pups. On the 8th day, MP and L, but not NP females showed robust pup-odor preferences. After the behavioral test, half of the females were exposed to pups for 2 h, whereas the other half were not. The females were then sacrificed to analyze brain oxytocin (OXT) and vasopressin (AVP) activities by cFos immunohistochemistry and to quantify their receptor mRNA expression using real-time PCR. In the paraventricular nucleus (PVN), the percentage of cFos-positive OXT neurons was significantly larger in MP and L females than in NP females after pup exposure. No significant differences were found in cFos expression in OXT neurons of the supraoptic nucleus (SON) or in AVP neurons of either the PVN or SON. Expression of OXT receptor mRNA in the medial preoptic area and amygdala of the control groups was also higher in MP females than in NP females. Finally, we demonstrated that infusion of OXT into the lateral ventricle of NP females promoted preferences for pup odors. These results indicate that puerperal and parental experiences enhance the responsiveness of OXT neurons in the PVN to pup stimuli and establish olfactory preferences for these odors in a parity-dependent manner.  相似文献   

A new liquid-type diet for leptocephali in mass production of artificial glass eels     

Yamada  Yoshiaki  Okamura  Akihiro  Mikawa  Naomi  Horie  Noriyuki  Tsukamoto  Katsumi 《Fisheries Science》2019,85(3):545-551

Fisheries Science - Development of artificial production of glass eels still presents many problems to be solved. What and how to feed larvae is one of the most crucial problems for commercial mass...  相似文献