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31.
Fungus-growing ants (Attini) live in an obligate mutualism with the fungi they cultivate for food. Because of the obligate nature of this relationship, the success of the ants is directly dependent on their ability to grow healthy fungus gardens. Attine ants have evolved complex disease management strategies to reduce their gardens exposure to potential parasitic microbes, to prevent the establishment of infection in their gardens, and to remove infected garden sections. The infrabuccal pocket, a filtering device located in the oral cavity of all ants, is an integral part of the mechanisms that leaf-cutter ants use to prevent the invasion and spread of general microbial parasites and the specific fungal-garden parasite Escovopsis. Fungus-growing ants carefully groom their garden, collecting general debris and pathogenic spores of Escovopsis in their infrabuccal pocket, the contents of which are later expelled in dump chambers inside the nest or externally. In this study we examined how a phylogenetically diverse collection of attine ants treat their infrabuccal pellets. Unlike leaf-cutters that deposit their infrabuccal pellets directly in refuse piles, ants of the more basal attine lineages stack their infrabuccal pellets in piles located close to their gardens, and a separate caste of workers is devoted to the construction, management, and eventual disposal of these piles. 相似文献
32.
Thermodynamic and kinetic studies on the adsorption of Cs+ and Sr2+ by Na-exchanged clinoptilolite-rich zeolite rock from Akita (Northern Japan) were performed for the purpose of nuclear waste treatment. The thermodynamic parameters such as selectivity coefficient, thermodynamic equilibrium constant, and standard free energy of exchange were evaluated. These values indicated that the selectivity order was determined as Cs+ > Na+ > Sr2+. In order to discuss the adsorption mechanism of Cs+ and Sr2+ onto Na-exchanged clinoptilolite, the effective diffusion coefficients were calculated and two kinetic models, pseudo-first-order and pseudo-second-order kinetic model, were tested. For all systems studied, chemisorption seems significant in the rate-controlling step, and the pseudo-second-order kinetic model provided the best correlation of the experimental data. 相似文献
33.
M Kawaguchi Y Sugahara T Watanabe K Irie M Ishida D Kurokawa S Kitamura H Takata IC Handoh K Nakayama Y Murakami 《Environmental science and pollution research international》2011,19(7):2488-2497
BACKGROUND AND OBJECTIVE: Spills of heavy oil (HO) over the oceans have been proven to have an adverse effect on marine life. It has been hypothesized that exposure of early larvae of sinking eggs to HO leads largely to normal morphology, whereas abnormal organization of the developing neural scaffold is likely to be found. HO-induced disruption of the nervous system, which controls animal behavior, may in turn cause abnormalities in the swimming behavior of hatched larvae. To clarify the toxicological effects of HO, we performed exposure experiments and morphological and behavioral analyses in pufferfish (Takifugu rubripes) larvae. EXPERIMENTAL PROCEDURE: Fertilized eggs of pufferfish were exposed to 50?mg/L of HO for 8?days and transferred to fresh seawater before hatching. The hatched larvae were observed for their swimming behavior, morphological appearance, and construction of muscles and nervous system. RESULTS AND DISCUSSION: In HO-exposed larvae, we did not detect any anomaly of body morphology. However, they showed an abnormal swimming pattern and disorganized midbrain, a higher center controlling movement. Our results suggest that HO-exposed fishes suffer developmental disorder of the brain that triggers an abnormal swimming behavior and that HO may be selectively toxic to the brain and cause physical disability throughout the life span of these fishes. 相似文献
34.
Selecting a phytoextraction plant with high Cd-accumulating ability based on the plant's compatibility with mechanized cultivation techniques may yield more immediately practical results than selection based on high tolerance to Cd. Rice (Oryza sativa L., cv. Nipponbare and Milyang 23), soybean (Glycine max [L.] Merr., cv. Enrei and Suzuyutaka), and maize (Zea mays L., cv. Gold Dent) were grown on one Andosol and two Fluvisols with low concentration of Cd contamination ranging from 0.83 to 4.29 mg Cd kg(-1), during 60 days in pots (550 mL) placed in a greenhouse. Shoot Cd uptake was as follows: Gold Dent相似文献
35.
The contribution of non-point sources to perfluorinated surfactants (PFSs) in a river was evaluated by estimating their fluxes and by using boron (B) as a tracer. The utility of PFSs/B as an indicator for evaluating the impact of non-point sources was demonstrated. River water samples were collected from the Iruma River, upstream of the intake of drinking water treatment plants in Tokyo, during dry weather and wet weather, and 13 PFSs, dissolved organic carbon (DOC), total nitrogen (TN), and B were analyzed. Perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS), perfluoroheptanoate (PFHpA), perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorodecanoate (PFDA), perfluoroundecanoate (PFUA), and perfluorododecanoate (PFDoDA) were detected on all sampling dates. The concentrations and fluxes of perfluorocarboxylates (PFCAs, e.g. PFOA and PFNA) were higher during wet weather, but those of perfluoroalkyl sulfonates (PFASs, e.g. PFHxS and PFOS) were not. The wet/dry ratios of PFSs/B (ratios of PFSs/B during wet weather to those during dry weather) agreed well with those of PFS fluxes (ratios of PFS fluxes during wet weather to those during dry weather), indicating that PFSs/B is useful for evaluating the contribution from non-point sources to PFSs in rivers. The wet/dry ratios of PFOA and PFNA were higher than those of other PFSs, DOC, and TN, showing that non-point sources contributed greatly to PFOA and PFNA in the water. This is the first study to use B as a wastewater tracer to estimate the contribution of non-point sources to PFSs in a river. 相似文献
36.
We investigated perfluorinated surfactants (PFSs) in size-fractionated street dust to identify their occurrence, contributions from traffic, and potential routes of entry into waters. Street dust was collected from residential areas and heavily trafficked areas in Tokyo and sorted into fine (<63 microm) and coarse fractions (63-2000 microm). Five PFS species were analyzed by liquid chromatography-tandem mass spectrometry: perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorodecanoate (PFDA), and perfluoroundecanoate (PFUA). In fine fractions, PFS contents were significantly higher in heavily trafficked street dust than in residential street dust, but in coarse fractions, no significant differences were observed. Additionally, in heavily trafficked areas, PFS contents were significantly higher in fine fractions than in coarse fractions, but in residential areas, no significant differences were observed. PFS compositions differed between size fractions, not locations, indicating differences in sources between size fractions. Fine particles from traffic contributed to PFSs in street dust. Street dust possibly acts as the origin of PFSs in street runoff and eventually enters waters. This is the first report of PFSs in street dust. 相似文献
37.
The increasing infrastructure instability is an important issue in relation to the influences of global climate change in
urban areas. A serious issue pertaining to this is the dual nature of damage triggered by events combined with climate change
and natural hazards. For example, catastrophic damage could result from the combination of global warming with a great earthquake,
which is a worst-case scenario. Although this worst-case scenario has rarely occurred and presents a low probability of occurrence,
countermeasures must be prepared in advance based on an appropriate response and adaptation strategies. After an overview
of possible infrastructural instabilities caused by global warming, methodologies are proposed placing emphasis on the increasing
probability of infrastructural instability triggered by natural hazards resulting from groundwater-level (GWL) variations.
These effects are expected to be particularly serious in coastal regions because of the influence of the rising sea level
resulting from global warming. The influence of sea-level rises (SLR) will become apparent along with land subsidence because
groundwater abstraction will become severe in coastal regions. Additionally, the probability of earthquake liquefaction increases
if GWL rises in accompaniment with SLR. Using case histories, we examined the possible occurrence of these natural hazards
as a result of global warming. Finally, possible countermeasures and adaptation strategies for reducing and mitigating infrastructure
damage accelerated by global warming are described for each case in specific regions. In particular, special attention should
be paid to adaptation strategies in coastal lowlands, which particularly suffer from the effects of land subsidence. 相似文献
38.
Saito-Kokubu Y Yasuda K Magara M Miyamoto Y Sakurai S Usuda S Yamazaki H Yoshikawa S Nagaoka S Mitamura M Inoue J Murakami A 《Journal of environmental radioactivity》2008,99(1):211-217
In a sediment core of Nishiyama reservoir at Nagasaki city, depth profiles of (240)Pu/(239)Pu isotopic ratio, (239+240)Pu and (137)Cs activities were determined. Sediments containing plutonium and (137)Cs, which were deposited immediately after a detonation of Nagasaki atomic bomb, were identified in the core. Observed below the sediments were macroscopic charcoals, providing evidence for initial deposit of the fallout of the Nagasaki atomic bomb. This is the first entire depositional records of plutonium and (137)Cs released from the Nagasaki atomic bomb together with those from atmospheric nuclear tests. 相似文献
39.
The lipid and fatty acid composition of male and female Penaeus japonicus Bate was investigated over a period of 11 months to determine the effects of environmental and nutritional factors such as temperature and starvation. The lipid content of the prawns increases from May to November, whereas water content decreases. We observed a time-lag between the highest lipid rate of males (in November) and that of females (in October); this is probably related to ovarian metabolism. From September to March, the high lipid content of the females coincided with a high percentage of monounsaturated fatty acids (especially 16:1 and 18:1). Winter starvation induces a decrease in palmitic acid content. As temperature decreases, the monounsaturated (16:1, 18:1) and polyunsaturated (20:4, 20:5, 22:6) fatty acids increase at the expense of the saturated fatty acids (16:0, 18:0) in the adult prawn. However, in post-larvae and juveniles, this increased rate of polyunsaturated fatty acids would be related to their particular lipid metabolism. 相似文献
40.
The mating frequency of queens was estimated for eight attine ant species, Myrmicocrypta ednaella, Apterostigma mayri, Cyphomyrmex costatus, C. rimosus (four lower attines), Trachymyrmex isthmicus, Serico-myrmex amabalis, Acromyrmex octospinosus and Atta colombica (four higher attines), and correlated to colony size, worker polyethism, and sex ratio. Mating frequency was calculated from
within-colony relatedness estimated by CAP-PCR DNA fingerprinting. Most queens of lower attines and T. isthmicus mated with only one male, while those of the three higher attines mated with multiple males. Mating frequency was positively
correlated with colony size. Polyethism among workers was dependent on worker age in lower attines but on body size in higher
attines, suggesting some correlation between mating frequency (i.e., within-colony gene diversity) and caste complexity. The
sex ratio was biased toward females in species where the mating frequency equaled one, but toward males in species where the
mating frequency was greater than two. Changing in nest site from ground surface to deep underground may have facilitated
the evolution of large colony size in Attini, and this may have resulted in the evolution of polyandry (a queen mates with
multiple males). With the evolution of polyandry in higher attines, Atta and Acromyrmex in particular have generated high genetic diversity within their colonies and complex social structures.
Received: 26 October 1999 / Revised: 25 May 2000 / Accepted: 24 June 2000 相似文献