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61.
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
62.
To formulate successful phytostabilization strategies in a shooting range soil, understanding how heavy metals are immobilized at the molecular level in the rhizosphere soil is critical. Lead (Pb) speciation and solubility in rhizosphere soils of five different plant species were investigated using extended X-ray absorption fine structure (EXAFS) spectroscopy and chemical extraction. The EXAFS analysis indicated that Pb occurred as PbCO (37%), Pb sorbed to organic matter (Pb-org: 15%), and Pb sorbed to pedogenic birnessite and/or ferrihydrite (Pb-ox: 36%) in the bulk soil. Comparison of the EXAFS spectra between bulk and rhizosphere soils demonstrated notable differences in fine structure, indicating that Pb species had been modified by rhizosphere processes. The estimated proportion of PbCO (25%) in the buckwheat soil was smaller than the other rhizosphere soils (35-39%). The addition of P significantly reduced Pb solubility in the bulk and rhizosphere soil except in the rhizosphere of buckwheat, for which the Pb solubility was 10-fold greater than in the other P-amended soils. This larger solubility in the buckwheat rhizosphere could not be explained by the total Pb speciation in the soil but was presumably related to the acidifying effect of buckwheat, resulting in a decrease of the soil pH by 0.4 units. The reduced Pb solubility by P amendment resulted from the transformation of preexisting PbCO (37%) into Pb(PO)Cl (26-32%) in the bulk and rhizosphere soils. In the P-amended rhizosphere soils, Pb-org species were no longer detected, and the Pb-ox pool increased (51-57%). The present study demonstrated that rhizosphere processes modify Pb solubility and speciation in P-amended soils and that some plant species, like buckwheat, may impair the efficiency of Pb immobilization by P amendments. 相似文献
63.
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
64.
Guido Grause Takahisa Hosoya Kazumi Hashimoto Tomohito Kameda Toshiaki Yoshioka 《Journal of Material Cycles and Waste Management》2014,16(3):519-524
The modification of poly(vinyl chloride) was carried out with iminodiacetic acid (IDA, C4H7NO4) and iminodiacetic acid dimethylester (IDADM, C6H11NO4), as well as with n-dodecanethiol (DT, C12H26S) in the presence of K2CO3. The reaction was carried out at different temperatures below 100 °C with dimethyl formamide (DMF) and cyclohexanone as solvents. IDA did not show any reactivity, probably due to the dipolar character of the molecule. IDADM caused the elimination of HCl, while only substitution ratios of about 3 % were observed. However, the modification of PVC with DT resulted in a substitution rate of 18 % without elimination. DT-PVC showed excellent thermal properties, comparable with those of the unmodified polymer. 相似文献
65.
Hydroxylated polycyclic aromatic hydrocarbons (OH-PAH) with less than four rings are frequently found in the environment, whereas the toxicities associated with these compounds remain unclear. In this study, aryl hydrocarbon receptor (AhR)–ligand binding activities of OH-PAH were investigated by using a recombinant yeast assay system. The majority of the OH-PAH tested showed AhR–ligand binding activities, especially, when the hydroxylated derivatives of naphthalene were incubated with recombinant yeast. The structure–activity relationship between AhR activity and molecular weight or the octanol–water partition coefficient value of OH-PAH displayed significant correlations. These findings indicate that the site and number of hydroxy-groups substituted on PAH skeleton apparently influenced the AhR – ligand binding activity in the recombinant yeast assay. 相似文献
66.
67.
The salting-out effect by seawater constituents on the water solubilities of 11 aromatic compounds, anthracene, pyrene, phenanthrene, biphenyl, naphthalene, p-nitrotoluene, p-toluidine, o-nitrophenol, m-nitrophenol, p-nitrophenol and phenol was investigated. A best fit equation (r = 0.965) for the salting-out parameters, K, and distilled water solubilities, So, at 20°C was found to be K = ?0.0298 log So + 0.114. Seawater solubilities, S, predicted for solutions of ionic strength, I, using the equation log S = (0.0298 I + 1) log So ? 0.114 I were in agreement with observed values within 13 % (average 4.8 %) and there were no significant differences between values from the Pacific Ocean seawater and those from 35 o/oo NaCl solutions. It was concluded that dissolved organic matter in seawater had an insignificant effect for the test chemicals. 相似文献
68.
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
69.
Shigehiro Hirano Shuntaro Kitaura Nozomi Sasaki Hiroaki Sakaguchi Masafumi Sugiyama Kunihiko Hashimoto Akira Tanatani 《Journal of Polymers and the Environment》1996,4(4):261-265
Chitin biodegradation and wounded bark tissue healing were demonstrated in several evergreen and deciduous trees by dressing with a sheet of chitin-containing films or sponges. Chitinase activities in the tree bark tissues around the wounds were enhanced by this treatment up to four times those of the untreated wounds. Significant seasonal changes of chitinase activities were observed with the bark and leaf tissues of deciduous trees, but few with those of evergreen trees. A sheet of chitin films implanted or dressed in the tree bark tissues was biodegraded within 4 to 24 weeks after implantation and was assimilated into the wounded bark tissues, resulting in the stimulation of the wounded bark tissue healing. 相似文献
70.
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