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991.
Evaluation of carbon dynamics is of great concern worldwide in terms of climate change and soil fertility. However, the annual CO2 flux and the effect of land management on the carbon budget are poorly understood in Sub-Saharan Africa, owing to the relative dearth of data for in situ CO2 fluxes. Here, we evaluated seasonal variations in CO2 efflux rate with hourly climate data in two dry tropical croplands in Tanzania at two sites with contrasting soil textures, viz. clayey or sandy, over four consecutive crop-cultivation periods of 40 months. We then: (1) estimated the annual CO2 flux, and (2) evaluated the effect of land management (control plot, plant residue treatment plot, fertilizer treatment plot, and plant residue and fertilizer treatment plot) on the CO2 flux and soil carbon stock at both sites. Estimated annual CO2 fluxes were 1.0–2.2 and 0.9–1.9 Mg C ha?1 yr?1 for the clayey and sandy sites, respectively. At the end of the experiment, crop cultivation had decreased the surface soil carbon stocks by 2.4 and 3.0 Mg C ha?1 (soil depth 0–15 cm) at the clayey and sandy sites, respectively. On the other hand, plant residue application (7.5 Mg C ha?1 yr?1) significantly increased the surface soil carbon stocks, i.e., 3.5–3.8 and 1.7–2.1 Mg C ha?1 (soil depth 0–15 cm) at the clayey and sandy sites, respectively, while it also increased the annual CO2 fluxes substantially, i.e., 2.5–4.0 and 2.4–3.4 Mg C ha?1 yr?1 for the clayey and sandy soils, respectively. Our results indicate that these dry tropical croplands at least may act as a carbon sink, though the efficiency of carbon accumulation was substantially lower in sandy soil (6.8–8.4%) compared to clayey soil (14.0–15.2%), possibly owing to higher carbon loss by leaching and macro-faunal activity. 相似文献
992.
Yuichi Iwasaki Takashi Kagaya Ken-ichi Miyamoto Hiroyuki Matsuda 《Water, air, and soil pollution》2012,223(1):145-158
We conducted a field survey in Japanese streams and rivers to generate useful information about whether the Japanese water
quality standard for zinc (Zn) in the freshwater environment (30 μg/L) is over- or underprotective of the populations and
communities of lotic benthic macroinvertebrates. Many macroinvertebrate populations were reduced and community characteristics
were altered at two polluted sites with Zn concentrations above 1,000 μg/L as compared with control sites with Zn concentrations
below 30 μg/L. In contrast, at least one site among three polluted sites with Zn concentrations of 80–126 μg/L experienced
noncritical effects (i.e., no significant difference was observed between the sample mean at a polluted site and that at the
control sites, and the sample mean was within the minimum–maximum range of those at the control sites) for most of the ten
community metrics for diversity and abundance. In addition, the abundances of 95% of the dominant taxa were not always significantly
lower at more than one polluted site (Zn concentrations, ≥80 μg/L). Our results suggest that Zn concentrations below approximately
100 μg/L are likely to protect most aspects of richness and abundance of the riverine macroinvertebrate communities in the
study areas. This study shows a case that the Japanese Zn standard is likely overprotective of the macroinvertebrate populations
and communities. 相似文献
993.
Kazuya Sato Masaki Okamoto Yuta Suzuki Kagehisa Kiba Hiroki Tatsumi Hisashi Teramura Toshitaka Ikeuchi 《Fisheries Science》2013,79(6):943-948
The transactivational property of natural and synthetic chemicals via medaka GR1b was investigated after development of a stable cell line for the reporter gene assay. In our study, cortisol was the most potent agonist among the natural corticoids assayed for potency [EC50 (concentration of agonist provoking a response halfway between the baseline and maximum response) 68 nM] and efficacy. Three artificial corticosteroids, namely, dexamethasone [EC50 16 nM, relative agonistic activity to cortisol (RAA) 144 %], prednisolone (EC50 81 nM, RAA 116 %) and clobetasol propionate (EC50 0.10 nM, RAA 220 %), showed strong agonistic activity and were more potent than the original corticoid, F. All synthetic corticoids used in our study were full agonists. Interestingly, melengestrol acetate, a synthetic progestogen, induced luciferase activity in a dose-dependent manner. Based on its EC50 value and RAA of 29 nM and 57 %, respectively, this molecule was assessed as a partial agonist. None of the other steroids and chemicals assayed in our study induced an agonistic response. In conclusion, we successfully developed a stable reporter gene assay that can be used to assess the transactivational property of glucocorticoid-like chemicals toward medaka GR1b. 相似文献
994.
Takeshi Yamamoto Hiroyuki Matsunari Takashi Iwasaki Hiroshi Hashimoto Isao Kai Hiroto Hokazono Kazuhisa Hamada Kazuhisa Teruya Takashi Hara Hirofumi Furuita Keiichi Mushiake 《Fisheries Science》2013,79(2):269-275
This study examined the changes in mineral concentrations in amberjack Seriola dumerili larvae during seed production taking into consideration the mineral concentrations of rotifers in the larval rearing tanks (tank rotifers), since the concentrations of certain minerals in tank rotifers have been reported to be very high. In the present study, the concentrations of Ca, Mg, Fe, Zn and Mn in tank rotifers were generally higher than in freshly enriched rotifers. The extent of the increase in tank rotifers varied depending on the mineral, larval production facility and larval production trial. Concentrations of Ca in the larvae increased as they grew, those of P and Mn increased up to ca. 30 days post-hatching (DPH), those of Mg and Fe increased up to ca. 20 DPH and then decreased, and those of Zn continuously decreased through the seed production periods (to ca. 40 DPH). However, there were no clear relationships between the mineral concentrations of the tank rotifers and the larvae. These results indicate that high concentrations of minerals in tank rotifers are not directly reflected in amberjack larvae. This suggests that amberjack larvae maintain their mineral status by controlling the uptake and/or excretion of food minerals. 相似文献
995.
It is important to select the most appropriate method for fish sampling in streams and rivers; the sampling efficiency as well as any negative effect of the method of fish sampling on fishes such as stress, injury, and mortality must be considered. This study aimed to investigate stress hormone responses in ayu Plecoglossus altivelis in reaction to direct current (DC) electrofishing, alternating current (AC) electrofishing, and cast netting in artificial streams. The mortality, injury rate, and catch efficiency of these catching methods were also compared. It was found that immediately after capture, fish caught using a cast net exhibited significantly higher cortisol levels than did control fish that were caught rapidly by a hand net. Cortisol levels did not differ between electroshocked fish and the controls. Time required to catch 12 fish was shorter when DC was used (20 s) than when AC was used (45 s). The time required to catch fish greatly increased when a cast net was used (840 s). Cortisol levels in DC electroshocked and control treatment groups were at resting levels 24 and 48 h after capture. However, higher cortisol levels were found in fish captured using a cast net at both these time points. Cortisol levels in AC electroshocked fish returned to lower levels at 24 h, but increased again at 48 h. Furthermore, 48 h following capture, the fish caught by AC electrofishing exhibited higher mortality (7.5 %) than those captured by other methods (0 %). Spinal injury was also detected in one of the fish in this group. Considering these findings, DC electrofishing is the most effective and least damaging method for collecting P. altivelis in streams with respect to stress, physical damage, and efficiency. 相似文献
996.
Severe spotting, blight and drop of leaves caused by Colletotrichum dematium were found on potted plants of Polygonatum falcatum, a liliaceous ornamental, in open fields in Kagawa Prefecture, Japan, in May 2001. This new disease was named anthracnose
of P. falcatum.
Keisuke Tomioka, Jouji Moriwaki, Toyozo Sato contributed equally to this work.
The fungal isolate and its nucleotide sequence data obtained in this study were deposited in Genebank, National Institute
of Agrobiological Sciences and the DDBJ/EMBL/GenBank databases under accessions MAFF239500 and AB334523, respectively. 相似文献
997.
Naoya Urasaki Shinji Kawano Hiroyuki Mukai Takashi Uemori Osamu Takeda Teruo Sano 《Journal of General Plant Pathology》2008,74(2):151-155
We developed a detection method for “Candidatus Liberibacter asiaticus”, causal agent of citrus huanglongbing, using isothermal and chimeric primer-initiated amplification
of nucleic acids combined with cycling probe technology (Cycleave ICAN). With Cycleave ICAN, the reaction was done in one
tube in 1 h without the need for electrophoresis, and false positives were not generated. In addition, Cycleave ICAN method
was more sensitive than the conventional PCR method. Cycleave ICAN helps shorten the time for the large-scale detection needed
to manage huanglongbing. 相似文献
998.
Toyozo Sato Yumi Iwamoto Keisuke Tomioka Satoshi Taba Atsushi Ooshiro Kazuko Takaesu 《Journal of General Plant Pathology》2008,74(1):91-93
Stem rot and wilt of Jew’s marrow (nalta jute, Corchorus olitorius) were found on Is. Okinawa, Okinawa Prefecture, Japan, in March 2000. An anamorphic fungus, Lasiodiplodia theobromae was isolated repeatedly from the diseased plants and demonstrated to cause the disease. We coined the Japanese name “kurogare-byô” of Jew’s marrow for the present disease because it was new to Japan, although it had already been reported in India and Bangladesh as black band of the plant. 相似文献
999.
Keisuke Tomioka Hiroyuki Sawada Takayuki Aoki Toyozo Sato 《Journal of General Plant Pathology》2008,74(5):405-407
Severe blight of stems, leaves and pods caused by Botrytis cinerea was found on pearl lupine (Lupinus mutabilis), a legume crop, grown in Kagawa Prefecture, Japan, in March–June 1996–2002. This disease was named “gray mold of pearl lupine”
as a new disease.
One of the fungal isolates obtained in this study was deposited in Genebank, National Institute of Agrobiological Sciences
as accession MAFF238557. 相似文献
1000.
Zhihua Tao Minoru Sato Kegang Wu Hiromasa Kiyota Toshiyasu Yamaguchi Toshiki Nakano 《Fisheries Science》2012,78(4):923-926
We established a simple, rapid method for gizzerosine analysis in fish meal. Gizzerosine was extracted from fish meal with 0.1?N HCl solution. Samples and standard gizzerosine solutions were absorbed onto a paper disc, which was then set on electrophoresis paper for 18?min, and the paper was dried. Gizzerosine was visualized with Pauly??s reagent, and the intensity of the colored spots was digitized and calculated by image processing method software. We achieved successful separation of gizzerosine from other Pauly??s reagent-positive components in fish meal extracts. The linearity of gizzerosine estimation using this method was within the range 30?C1000?ng (R 2?=?0.99). Gizzerosine was satisfactorily detected and completely separated from histamine and other Pauly??s reagent-positive compounds. This method does not require expensive instruments or tedious pretreatment to eliminate interfering compounds, such as histamine or histidine. It also uses less reagent compared with high-performance liquid chromatography. Moreover, it is a simple, rapid, sensitive, and reproducible method. It is suitable for monitoring gizzerosine in fish meal products that contain as little as 10?ppm gizzerosine. 相似文献