Otolith microstructural analysis of reared larvae of the Japanese eel Anguilla japonica   总被引：1，自引：0，他引：1  

Akira  SHINODA  Hideki  TANAKA  Hirohiko  KAGAWA  Hiromi  OHTA  Katsumi  TSUKAMOTO 《Fisheries Science》2004,70(2):339-341

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Involvement of steroid hormones in the preovulatory gonadotropin surge in female goldfish     

Makito Kobayashi  Katsumi Aida  Isao Hanyu 《Fish physiology and biochemistry》1989,7(1-6):141-146

Goldfish,Carassius auratus, spawn several times within a spawning season. A gonadotropin (GtH) surge occurs at the time of ovulation in this cyprinid species. This ovulatory GtH surge mediates the processes of final oocyte maturation and ovulation, and occurs at the end of each spawning cycle. Within a cycle, there is a shift in the predominant plasma steroid from estradiol to testosterone, and finally 17α, 20β-dihydroxy-4-pregnen-3-one at the time of the ovulatory GtH surge. High levels of testosterone were always observed before ovulation. When ovariectomized or sexually regressed female goldfish were implanted with testosterone, they exhibited a GtH surge which was similar to those normally observed at ovulation. These results strongly suggest that elevated plasma testosterone is an important physiological requirement for the occurrence of the GtH surge.  相似文献   

Evaluation of technologies for sequestering carbon in agricultural land by using organic filter underdrains     

Iwao Kitagawa  Yasutaka Tsukamoto 《Paddy and Water Environment》2014,12(2):287-294

Technology for storing carbon in the subsoil of agricultural land using organic filter materials in underdrains was evaluated as an activity for sequestering CO₂ to mitigate global warming. First, the quantity of carbon remaining in wood chips and rice husks in underdrains was determined over 11 years after construction. Moreover, the quantity of CO₂ emissions from the construction of two underdrain types was calculated. Then, a survey was conducted to investigate the effect on greenhouse gas emissions of the filter material. The results indicate that greenhouse gas emissions would not increase. The quantity of storage carbon in the wood chip filter material of underdrains during their 15-year service life was estimated to be 6.76 tCO₂eq ha^?1. Rice husks, in contrast, were found ineffective in storing carbon. Therefore, the selection of the filter material for underdrains is important. The value of storage carbon in the wood chip filter material is similar to the amount of carbon sequestered by no-till farming, which is now being implemented as a global warming countermeasure based on soil management in agricultural land.  相似文献   

Increase of otolith Sr:Ca ratio related to metamorphosis and maturation in anchovy <Emphasis Type="Italic">Engraulis japonicus</Emphasis>     

Hiromu Zenitani  Naoaki Kono  Youichi Tsukamoto  Noritaka Mochioka 《Fisheries Science》2007,73(6):1395-1397

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Evaluation of technologies for sequestering carbon in agricultural land by using organic filter underdrains     

Kitagawa  Iwao  Tsukamoto  Yasutaka 《Paddy and Water Environment》2013,12(2):287-294

Technology for storing carbon in the subsoil of agricultural land using organic filter materials in underdrains was evaluated as an activity for sequestering CO₂ to mitigate global warming. First, the quantity of carbon remaining in wood chips and rice husks in underdrains was determined over 11 years after construction. Moreover, the quantity of CO₂ emissions from the construction of two underdrain types was calculated. Then, a survey was conducted to investigate the effect on greenhouse gas emissions of the filter material. The results indicate that greenhouse gas emissions would not increase. The quantity of storage carbon in the wood chip filter material of underdrains during their 15-year service life was estimated to be 6.76 tCO₂eq ha⁻¹. Rice husks, in contrast, were found ineffective in storing carbon. Therefore, the selection of the filter material for underdrains is important. The value of storage carbon in the wood chip filter material is similar to the amount of carbon sequestered by no-till farming, which is now being implemented as a global warming countermeasure based on soil management in agricultural land.

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Autophagy is essential for preimplantation development of mouse embryos   总被引：2，自引：0，他引：2  

Tsukamoto S  Kuma A  Murakami M  Kishi C  Yamamoto A  Mizushima N 《Science (New York, N.Y.)》2008,321(5885):117-120

After fertilization, maternal proteins in oocytes are degraded and new proteins encoded by the zygotic genome are synthesized. We found that autophagy, a process for the degradation of cytoplasmic constituents in the lysosome, plays a critical role during this period. Autophagy was triggered by fertilization and up-regulated in early mouse embryos. Autophagy-defective oocytes derived from oocyte-specific Atg5 (autophagy-related 5) knockout mice failed to develop beyond the four- and eight-cell stages if they were fertilized by Atg5-null sperm, but could develop if they were fertilized by wild-type sperm. Protein synthesis rates were reduced in the autophagy-null embryos. Thus, autophagic degradation within early embryos is essential for preimplantation development in mammals.  相似文献   

Responses of leaf photosynthesis and plant growth to altered source–sink balance in a Japanese and a Dutch tomato cultivar     

Ryo Matsuda  Katsumi Suzuki  Akimasa NakanoTadahisa Higashide  Masuyuki Takaichi 《Scientia Horticulturae》2011

We investigated the effects of altered source/sink ratio by leaf or fruit pruning on leaf photosynthetic characteristics and whole-plant growth of ‘Momotaro York’, a Japanese cultivar, and ‘Dundee’, a Dutch cultivar and verified a hypothesis for sink-limitation of plant growth proposed by Tanaka and Fujita (1974). Plants were grown hydroponically with a high-wire system in a greenhouse for 11 weeks. Light-saturated photosynthesis of young, fully expanded leaves measured at atmospheric CO₂ partial pressure of 37 Pa and at an intercellular CO₂ partial pressure of 20 Pa was not influenced by alteration of source/sink ratio for either cultivar. Although soluble sugars were accumulated in leaves under high source/sink conditions, the amount of ribulose-1,5-bisphosphate carboxylase/oxygenase, a rate-limiting factor for CO₂-limited photosynthesis, was not affected by the altered source–sink balance. Net assimilation rate of a whole plant increased with decreasing source/sink ratio, but this can be accounted for by the changes in light interception per unit leaf area, without taking the source–sink relationship into consideration. It was concluded that the altered source/sink ratio did not change leaf photosynthetic capacity and the sink-limitation hypothesis cannot be applied to either cultivar under the conditions of the present study.  相似文献   

Soil macro-fauna in an Acacia mangium plantation in comparison to that in a primary mixed dipterocarp forest in the lowlands of Sarawak, Malaysia     

Jiro Tsukamoto  John Sabang 《Pedobiologia》2005,49(1):69-80

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Paraticulate metals in waters of a typical irrigation river: The River Sakuragawa,Japan     

Humitake Seki  Masayuki Takahashi  Katsumi Kobayashi  Shozo Ishizaka 《Water, air, and soil pollution》1979,12(2):265-271

The particulate metallic elements in waters of a water system of the River Sakuragawa and Lake Kasumigaura were measured by the multielement analyses using particle-induced X-ray emission. The heavy metal particulates for environmental standards were less than 0.0001 ppm for Cd, 0.00037 ppm for Cr, and 0.00078 ppm both for Hg and Pb in the river waters. The predominant metal particles in the waters were Fe, Mn, and Zn.  相似文献   

Effects of phosphate supply and elevated CO2 on root acid phosphatase activity in Pinus densiflora seedlings     

Mariko Norisada  Tetsuya Motoshige  Katsumi Kojima  Takeshi Tange 《植物养料与土壤学杂志》2006,169(2):274-279

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