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41.
Comparison of telomere length among different life cycle stages of the jellyfish Cassiopea
andromeda
The polyp (scyphistoma) of the jellyfish Cassiopea andromeda reproduces asexually repeatedly, while the medusa, the sexually reproducing stage, exhibits a relatively shorter life span.
As a first step to understand the mechanism behind the differences in the life spans of the polyp and medusa stages of the
jellyfish, we compared the lengths of the telomere region of one targeted chromosome between the polyp and medusa stages using
a modified single telomere length assay (STELA). The double-stranded regions of the telomeres were amplified by PCR, and the
average length of the PCR products was estimated by densitometry analysis of the gel smear. Chromosomes within cells of the
bell region of the medusa were characterized by longer telomeres than those of polyps, asexual propagules, or other regions
of the medusa. This is the first study to estimate the telomere lengths of targeted chromosomes in a cnidarian and opens a
way to understand the mechanism underlying different life spans of the polyp and medusa stages. 相似文献
42.
When wind-induced water waves appear over the free-surface flows such as natural rivers and artificial channels, large amounts
of oxygen gas and heat are transported toward the river bed through the interface between water and wind layers. In contrast,
a bed region is a kind of turbulent boundary layer, in which turbulence generation and its transport is promoted by the production
of bed shear stress. In particular, coherent hairpin vortices, together with strong ejection events toward the outer part
of the layer, promote mass and momentum exchanges between the inner and outer layers. It is inferred that such a near-bed
turbulence may be influenced significantly by these air–water interfacial fluctuations accompanied with free-surface velocity
shear and wind-induced water waves. However, these wind effects on the wall-turbulence structure are less understood. To address
these exciting and challenging topics, we conducted particle imagery velocimetry (PIV) measurements in open-channel flows
combined with air flows, and furthermore the present measured data allows us to investigate the effects of air–water interactions
on turbulence structure through the whole depth region. 相似文献
43.
Haruka Ohashi Masato Yoshikawa Keiichi Oono Norihisa Tanaka Yoriko Hatase Yuhide Murakami 《Environmental management》2014,54(3):631-640
Irreversible shifts in ecosystems caused by large herbivores are becoming widespread around the world. We analyzed data derived from the 2009–2010 Sika Deer Impact Survey, which assessed the geographical distribution of deer impacts on vegetation through a questionnaire, on a scale of 5-km grid-cells. Our aim was to identify areas facing irreversible ecosystem shifts caused by deer overpopulation and in need of management prioritization. Our results demonstrated that the areas with heavy impacts on vegetation were widely distributed across Japan from north to south and from the coastal to the alpine areas. Grid-cells with heavy impacts are especially expanding in the southwestern part of the Pacific side of Japan. The intensity of deer impacts was explained by four factors: (1) the number of 5-km grid-cells with sika deer in neighboring 5 km-grid-cells in 1978 and 2003, (2) the year sika deer were first recorded in a grid-cell, (3) the number of months in which maximum snow depth exceeded 50 cm, and (4) the proportion of urban areas in a particular grid-cell. Based on our model, areas with long-persistent deer populations, short snow periods, and fewer urban areas were predicted to be the most vulnerable to deer impact. Although many areas matching these criteria already have heavy deer impact, there are some areas that remain only slightly impacted. These areas may need to be designated as having high management priority because of the possibility of a rapid intensification of deer impact. 相似文献
44.
Song JY Ohta S Nakayama K Murakami Y Kitamura S 《Environmental science and pollution research international》2012,19(6):2300-2304
Purpose
The immunotoxicities of oil and its components on fish immunities have been investigated, but there is little literature on the recovery of the fish from the immune suppression. Therefore, the recovery of Japanese flounder Paralichthys olivaceus from an immunosuppressive effect due to heavy oil (HO) exposure was investigated in this study.Methods
Fish were exposed to HO at a concentration of 0.385?g/L for 2?days, while control fish received no exposure. Seven fish were sampled at 0, 3, 7, and 14?days post-exposure. The respiratory rate was measured everyday as an indicator of the acute effect of HO exposure. Fish serum was collected and used for antibacterial activity assay against Edwardsiella tarda. Expression changes of respiratory and immune-related genes were evaluated by real-time PCR.Results and discussion
The respiratory rate was significantly increased in the HO-exposed group until 4?days post-exposure. A respiratory-related gene, ??-hemoglobin, was also significantly downregulated in the spleen both at 0 and 7?days post-exposure and kidney at 3?days post-exposure in HO-exposed fish. Immunotoxicity, including suppression of antibacterial activities and downregulation of the IgM gene, was observed in HO-exposed fish until 3?days post-exposure, but not after that time. From these results, we conclude that the fish likely return to normal status around 1?week. 相似文献45.
Watanabe M Adams RM Wu J Bolte JP Cox MM Johnson SL Liss WJ Boggess WG Ebersole JL 《Journal of environmental management》2005,75(2):93-104
This paper integrates economic, biological, and physical models to explore the efficient combination and spatial allocation of conservation efforts to protect water quality and increase salmonid populations in the Grande Ronde basin, Oregon. We focus on the effects of shade on water temperatures and the subsequent impacts on endangered juvenile salmonid populations. The integrated modeling system consists of a physical model that links riparian conditions and hydrological characteristics to water temperature; a biological model that links water temperature and riparian conditions to salmonid abundance, and an economic model that incorporates both physical and biological models to estimate minimum cost allocations of conservation efforts. Our findings indicate that conservation alternatives such as passive and active riparian restoration, the width of riparian restoration zones, and the types of vegetation used in restoration activities should be selected based on the spatial distribution of riparian characteristics in the basin. The relative effectiveness of passive and active restoration plays an important role in determining the efficient allocations of conservation efforts. The time frame considered in the restoration efforts and the magnitude of desired temperature reductions also affect the efficient combinations of restoration activities. If the objective of conservation efforts is to maximize fish populations, then fishery benefits should be directly targeted. Targeting other criterion such as water temperatures would result in different allocations of conservation efforts, and therefore are not generally efficient. 相似文献
46.
The atmospheric deposition of reactive nitrogen on turf grassland in Tsukuba, central Japan, was investigated from July 2003
to December 2004. The target components were ammonium, nitrate, and nitrite ions for wet deposition and gaseous ammonia, nitric
and nitrous acids, and particulate ammonium, nitrate, and nitrite for dry deposition. Organic nitrogen was also evaluated
by subtracting the amount of inorganic nitrogen from total nitrogen. A wet-only sampler and filter holders were used to collect
precipitation and the atmospheric components, respectively. An inferential method was applied to calculate the dry deposition
velocity of gases and particles, which involved the effects of surface wetness and ammonia volatilization through stomata
on the dry deposition velocity. The mean fraction of the monthly wet to total deposition was different among chemical species;
37, 77, and 1% for ammoniacal, nitrate-, and nitrite-nitrogen, respectively. The annual deposition of inorganic nitrogen in
2004 was 47 and 48 mmol m−2 yr−1 for wet and dry deposition, respectively; 51% of atmospheric deposition was contributed by dry deposition. The annual wet
deposition in 2004 was 20, 27, and 0.07 mmol m−2 yr−1, and the annual dry deposition in 2004 was 35, 7.4, and 5.4 mmol m−2 yr−1 for ammoniacal, nitrate-, and nitrite-nitrogen, respectively. Ammoniacal nitrogen was the most important reactive nitrogen
because of its remarkable contribution to both wet and dry deposition. The median ratio of the organic nitrogen concentration
to total nitrogen was 9.8, 17, and 15% for precipitation, gases, and particles, respectively. 相似文献
47.
Akira Hoshino Maso Tsuji Masanori Momochi Akiko Mizutani Hideo Sawada Setsuo Kohnami Hiroki Nakagomi Michio Ito Hisato Saida Munehiro Ohnishi Michimasa Hirata Masao Kunioka Masahiro Funabash Shogo Uematsu 《Journal of Polymers and the Environment》2007,15(4):275-280
Several ISO standards for determining the ultimate aerobic/anaerobic biodegradability of plastic materials have been published.
In particular, ISO 14855-1 is a common test method that measures evolved carbon dioxide using such methods as continuous infrared
analysis, gas chromatography or titration and others (ISO 14855-1(2005.9)). This method is a small-scale test for determining
the ultimate aerobic biodegradability of plastic materials, where the amounts of compost inoculum and test sample in one tenth
comparing with that of ISO 14855-1. This method is well versed in ISO/DIS 14855-2 which the carbon dioxide evolved from test
vessel is determined by gravimetric analysis of carbon dioxide absorbent. The focus of this study is to elucidate statistically
the results of round robin test by seven countries used MODA, which were various deviations among the experiments. 相似文献
48.
We have found that giant hornets (Vespa mandarinia japonica) are killed in less than 10 min when they are trapped in a bee ball created by the Japanese honeybees Apis cerana japonica, but their death cannot be solely accounted for by the elevated temperature in the bee ball. In controlled experiments, hornets
can survive for 10 min at the temperature up to 47°C, whereas the temperature inside the bee balls does not rise higher than
45.9°C. We have found here that the CO2 concentration inside the bee ball also reaches a maximum (3.6 ± 0.2%) in the initial 0–5 min phase after bee ball formation.
The lethal temperature of the hornet (45–46°C) under conditions of CO2 concentration (3.7 ± 0.44%) produced using human expiratory air is almost the same as that in the bee ball. The lethal temperature
of the honeybee is 50–51°C under the same air conditions. We concluded that CO2 produced inside the bee ball by honeybees is a major factor together with the temperature involved in defense against giant
hornets. 相似文献
49.
Local mate competition (LMC) has been postulated to be the primary factor of female-biased sex allocation. In animals such as aphids that exhibit seasonal alternations of clonal and sexual reproduction, there is a high possibility of intra-clonal mating and LMC. This possibility is more plausible for more fecund clones, but outbreeding is predicted for less fecund clones. We hypothesize that clones that are more fecund will gain higher fitness returns by reducing investment in males because of more intense LMC among clonal males. We tested this hypothesis by elucidating the clonal sex allocation patterns of the galling aphid Kaltenbachiella japonica, in which inbreeding and LMC appear to be common. Winged mothers that emerge from a gall, belonging to the same clone, produced males and sexual females asexually on a branch, without dispersing to other trees. The heavier the gall, the more winged mothers were produced from the gall. Individual mothers produced a constant number of males and a variable number of females. The clonal sex allocation to males was 39.8?%, on average, and decreased with increasing gall weight. This result showed that clones that were more fecund exhibited more female-biased sex allocation and thus supported our hypothesis. Furthermore, our results corroborated Stubblefield and Seger’s hypothesis for sex allocation in patch structure rather than Yamaguchi’s constant male hypothesis. We conclude that K. japonica clones are able to adjust their sex allocation patterns adaptively depending on the quality of resources in the galls. 相似文献
50.
Global nuclear weapons tests fallout of 137Cs in the northern hemisphere has been documented in the UNSCEAR (United Nations Scientific Committee on the Effect of Atomic Radiation) reports. However, many questions have arisen during the past three to four decades; e.g. the water column inventory of 137Cs in the North Pacific Ocean was two to three time higher than the cumulative decay corrected fallout at the same latitude as stated in the UNSCEAR reports. Here we show more precise spatial distribution of global 137Cs fallout primarily on the basis of global measurements in rain, seawater and soil, as data from 10 degrees x 10 degrees grids. A typical feature of geographical distribution is that two high global 137Cs fallout areas exist in the northern hemisphere, where the highest 137Cs fallout was observed in the globe. These areas correspond to crossovers of areas where larger precipitation amounts were expected and where higher stratosphere-troposphere exchange was expected. Our new estimate of 765 +/- 79 PBq as global 137Cs fallout for the northern hemisphere is 1.4 times higher than that of 545 PBq in the UNSCEAR reports. 相似文献