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排序方式： 共有149条查询结果，搜索用时 15 毫秒
1.
Mariano Carossino Rudy Bauer Mark A. Mitchell Charles O. Cummings Anke C. Sthr Nobuko Wakamatsu Kimberly Harper Ingeborg M. Langohr Kendra Schultz Maria S. Mitchell Daniel K. Howe Udeni B. R. Balasuriya 《Journal of veterinary diagnostic investigation》2021,33(3):554
Toxoplasma gondii is a zoonotic protozoan pathogen that infects many endothermic vertebrates, including humans; the domestic cat and other felids serve as the definitive host. Macropodids are considered highly susceptible to toxoplasmosis. Here, we describe the clinical, pathologic, and immunohistochemical findings of an outbreak of systemic toxoplasmosis in a mob of 11 red kangaroos (Macropus rufus), with high morbidity (73%) and mortality (100%) rates. Affected animals had either severe and rapidly deteriorating clinical conditions or sudden death, which was correlated with widespread necrotizing lesions in multiple organs and intralesional T. gondii organisms identified via MIC3-specific immunohistochemistry and confirmed by REP529-specific rtPCR. Quantification of parasites demonstrated the highest parasite density in pulmonary parenchyma compared with other tissues. Our study highlights the continued importance of this severe condition in Australian marsupials. 相似文献
2.
Nobuko Katayanagi Yuichiro Furukawa Tamon Fumoto 《Soil Science and Plant Nutrition》2013,59(3):360-372
The DNDC (DeNitrification-DeComposition)-Rice model, one of the most advanced process-based models for the estimation of greenhouse gas emissions from paddy fields, has been discussed mostly in terms of the reproducibility of observed methane (CH4) emissions from Japanese rice paddies, but the model has not yet been validated for tropical rice paddies under alternate wetting and drying (AWD) irrigation management, a water-saving technique. We validated the model by using CH4 and nitrous oxide (N2O) flux data from rice in pots cultivated under AWD irrigation management in a screen-house at the International Rice Research Institute (Los Baños, the Philippines). After minor modification and adjustment of the model to the experimental irrigation conditions, we calculated grain yield and straw production. The observed mean daily CH4 fluxes from the continuous flooding (CF) and AWD pots were 4.49 and 1.22?kg?C?ha?1?day?1, respectively, and the observed mean daily N2O fluxes from the pots were 0.105 and 34.1?g?N?ha?1?day?1, respectively. The root-mean-square errors, indicators of simulation error, of daily CH4 fluxes from CF and AWD pots were calculated as 1.76 and 1.86?kg?C?ha?1?day?1, respectively, and those of daily N2O fluxes were 2.23 and 124?g?N?ha?1?day?1, respectively. The simulated gross CH4 emissions for CF and AWD from the puddling stage (2 days before transplanting) to harvest (97 days after transplanting) were 417 and 126?kg?C?ha?1, respectively; these values were 9.8% lower and 0.76% higher, respectively, than the observed values. The simulated gross N2O emissions during the same period were 0.0279 and 1.45?kg?N?ha?1 for CF and AWD, respectively; these values were respectively 87% and 29% lower than the observed values. The observed total global warming potential (GWP) of AWD resulting from the CH4 and N2O emissions was approximately one-third of that in the CF treatment. The simulated GWPs of both CF and AWD were close to the observed values despite the discrepancy in N2O emissions, because N2O emissions contributed much less than CH4 emissions to the total GWP. These results suggest that the DNDC-Rice model can be used to estimate CH4 emission and total GWP from tropical paddy fields under both CF and AWD conditions. 相似文献
3.
Background
Invasive ecosystem engineers can facilitate their invasions by modifying the physical environment to improve their own performance, but this positive feedback process has rarely been tested empirically except in sessile organisms. The invasive crayfish Procambarus clarkii is an ecosystem engineer that destroys aquatic macrophytes, which provide a physical refuge for animal prey, and this destruction is likely to enhance vulnerability to predators. Using two series of mesocosm experiments, we tested the hypothesis that the invasive crayfish increases its feeding efficiency on animal prey by reducing submerged macrophytes, thus increasing its individual growth rate in a positive density-dependent manner.Results
In the first experiment, increasing crayfish density reduced both macrophytes and animal prey (dragonfly and chironomid larvae) and, importantly, increased the growth rate of individual crayfish, in accordance with our expectation. In the second experiment, we used artificial macrophytes to clarify whether the physical architecture of macrophytes itself protects animal prey and limits crayfish growth rate. Increasing the artificial macrophyte quantity not only increased the survival of animal prey, but also retarded the crayfish growth rate.Conclusions
We conclude that macrophytes strengthen bottom-up control of crayfish, but this effect can be relaxed by increasing the density of crayfish via reduction in macrophytes. This positive feedback process may explain the crayfish outbreaks and regime shifts occasionally observed in invaded freshwater ecosystems.4.
The gonadal sex differentiation in red sea bream, Pagrus major, which is one of the most important species for aquaculture in Japan, was revealed histologically. The suitable conditions for induction of all-male groups in the fish were investigated, and functional males were induced by the conditions of oral administration of 17α-methyltestosterone. The sex determination of this fish was also discussed. 相似文献
5.
Evaluation of intracranial pressure by transcranial Doppler ultrasonography in dogs with intracranial hypertension 总被引：3，自引：0，他引：3
Fukushima U Miyashita K Okano S Higuchi S Takase K Hagio M 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2000,62(3):353-355
Transcranial Doppler ultrasonography (TCD) has been used to confirm changes in cerebral hemodynamics. In this study, we investigated whether the parameters for the basilar artery measured by TCD were correlated with the intracranial and cerebral perfusion pressures in extreme intracranial hypertension. An intracranial hypertension model was produced in seven dogs by inflating a balloon inserted into the epidural space. The resistance index was compared with the corresponding intracranial pressure and cerebral perfusion pressure values during intracranial hypertension. A significant correlation was recognized between the resistance index and cerebral perfusion pressure. Therefore, measurement of the basilar artery by TCD in the dog with intracranial hypertension is useful in estimating the intracranial circulation in cases where the measurement of intracranial pressure is not available or not indicated. 相似文献
6.
7.
Kentaro Honda Haruka Kagiwada Nobuyuki Takahashi Kazushi Miyashita 《Ecology of Freshwater Fish》2012,21(4):640-657
Behavioural tracking of endangered adult Sakhalin taimen (Parahucho perryi) by acoustic telemetry was conducted in the Bekanbeushi River system that flows through eastern Hokkaido in 2008–2010. A total of 39 tracked P. perryi showed extensive use of the river system, both upstream and downstream, regardless of the month or year. No tracked adult P. perryi stayed in the ocean for more than 1 day. Some of the fish (20%) dwelled in upstream habitat consistently from spring to autumn, while 40% of individuals showed wide utilisation of the entire upstream and downstream systems. Although 39.4% of tracked fish utilised two or more primary tributaries to the main river, 6.1% used only the main river system. Distinct variability was observed between individuals based on the proportion of time spent in each stream reach (up‐, mid‐, and downstream). A trend was observed in 2008 and 2010 showing that tracked fish moved to the upper stream reaches when water temperatures downstream increased. This trend was not observed in 2009 when the summer water temperature downstream was more than 2 °C below average when compared to 2008 and 2010. Our results suggest that adult P. perryi in the Bekanbeushi River system exhibit high behavioural plasticity, that is, the fish can select habitats based on their own individual requirements. Our results also demonstrate the importance of physical continuity among river reaches both upstream and downstream such that P. perryi does not experience barriers in moving to optimal habitats. 相似文献
8.
Plants respond to attack by pathogens through various defense mechanisms. These defense responses are triggered by a variety of molecules derived from pathogenic microorganisms as well as host plants. In this study, we developed a high-throughput screening method using a cell-based lawn format assay for the identification of novel peptides that can induce plant defense responses from combinatorial peptide libraries. Solid-phase peptide libraries were synthesized using a photocleavable linker and immobilized using agarose gel. The peptides were partially cleaved from beads, and the agarose gel was layered on the tobacco cells. The defense response was then observed by detecting the generated H2O2 using a sensitive H2O2 indicator dye, N-(carboxymethylaminocarbonyl)-4,4'-bis(dimethylamino)diphenylamine sodium salt (DA-64). Using this assay format, a 6859-member peptide library based on the sequence of flagellin-derived peptides was screened, and several structural features important for the activity were obtained. 相似文献
9.
The duality of teleost gonadotropins 总被引：5，自引：0，他引：5
Hiroshi Kawauchi Kunimasa Suzuki Hiromichi Itoh Penny Swanson Nobuko Naito Yoshitaka Nagahama Masumi Nozaki Yasumitu Nakai Seiga Itoh 《Fish physiology and biochemistry》1989,7(1-6):29-38
The duality of salmon gonadotropins has been proved by biochemical, biological, and immunological characterization of two
chemically distinc gonadotropins. GTH I and GTH II were equipotent in stimulating estradiol production, whereas GTH II appears
to be more potent in stimulating maturational steroid synthesis. The ratio of plasma levels and pituitary contents of GTHs
and the secretory control by a GnRH suggest that GTH I is the predominant GTH during vitellogenesis and early stages of spermatogenesis
in salmonids, whereas GTH II is predominant at the time of spermiation and ovulation. GTH I and GTH II are found in distinctly
separate cells. In trout, GTH I is expressed first in ontogeny, whereas GTH II cells appear coincident with the onset of spermatogenesis
and vitellogenesis, and increase dramatically at the time of final reproductive maturation. Comparison of the amino acid sequences
of polypeptides and the base sequences of cDNA revealed that salmon GTH I β is more similar to bovine FSHβ than bovine LHβ
and salmon GTH II β shows higher homology to bovine LHβ than to bovine FSHβ. The existence of two pituitary gonadotropins
in teleosts as well as tetrapods suggests that the divergence of the GTH gene took place earlier than the time of divergence
of teleosts from the main line of evolution leading to tetrapods. 相似文献
10.