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541.
Lopez-Espinosa MJ Kiviranta H Araque P Ruokojärvi P Molina-Molina JM Fernandez MF Vartiainen T Olea N 《Chemosphere》2008,73(6):967-971
Seventeen polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were quantified in adipose tissue samples of non-occupationally exposed women living in Southern Spain. Geometric mean levels of sum of congeners and WHO(PCDD/F)-TEQ(2005) were 410 and 17.9pgg(-1) fat, respectively. Among PCDDs, octachlorodibenzo-p-dioxin (OCDD) showed the highest concentration with a mean value of 265pgg(-1) fat, followed by 1,2,3,6,7,8-HxCDD (49.3pgg(-1) fat) and 1,2,3,4,6,7,8-HpCDD (45.2pgg(-1) fat). These three congeners were responsible for around 90% of the sum of all PCDD/F congeners in adipose tissue. The geometric mean 2,3,7,8-TCDD value was 1.87pgg(-1) fat. 2,3,4,7,8-PeCDF (8.43pgg(-1) fat) showed the highest concentration among the PCDFs, followed by 1,2,3,4,7,8-HxCDF (4.17pgg(-1) fat) and 1,2,3,6,7,8-HxCDF (3.28pgg(-1) fat), and these three congeners were responsible for 4% of the sum of all studied PCDD/F congeners in adipose tissue and 76% of the sum of ten PCDFs. 1,2,3,7,8,9-HxCDF was the only congener not quantified in any sample, while 1,2,3,4,7,8,9-HpCDF, 1,2,3,7,8-PeCDF, OCDF and 2,3,7,8-TCDF were found in 5, 16, 16 and 19 samples, respectively. All other congeners were quantifiable in all 20 samples. Congeners contributing most to the WHO(PCDD/F)-TEQ(2005) were 1,2,3,7,8-PeCDD (31.6%), 1,2,3,6,7,8-HxCDD (28.3%) and 2,3,4,7,8-PeCDF (14.6%). The body burden of log-transformed WHO(PCDD/F)-TEQ(2005) levels increased with age (B=0.02; 95% CI=0.01, 0.03; p=0.02). Although these adipose tissue PCDD/F levels are similar to previously published findings in Spain and other European countries, further research is needed to determine trends in the exposure of women to these chemical residues. 相似文献
542.
The impact of the 2004 tsunami on coastal Thai communities: assessing adaptive capacity 总被引:1,自引:0,他引:1
Paton D Gregg CE Houghton BF Lachman R Lachman J Johnston DM Wongbusarakum S 《Disasters》2008,32(1):106-119
The suddenness and scale of the 26 December 2004 tsunami and the challenges posed to affected communities highlighted the benefits of their members having a capacity to confront and adapt to the consequences of such a disaster. Research into adaptive capacity or resilience has been conducted almost exclusively with Western populations. This paper describes an exploratory study of the potential of a measure of collective efficacy developed for Western populations to predict the capacity of members of a collective society, Thai citizens affected by the 2004 tsunami, to confront effectively the recovery demands associated with this disaster. Following a demonstration that this measure could predict adaptive capacity, the role of religious affiliation, ethnicity and place of residence in sustaining collective efficacy is discussed. The implications of the findings for future research on, and intervention to develop, adaptive capacity among Thai citizens in particular and collectivist societies in general are discussed. 相似文献
543.
The natural diet of Callinectes ornatus in Ubatuba Bay, Ubatuba (SP), Brazil, was studied. Influence of season, sex, size and molt stage variation in the diet were
also described. Specimens were collected monthly over a period of 1 year, in Ubatuba Bay, using a fishing boat equipped with
a double rigged net. The relative degree of stomach fullness, frequency of occurrence, and quantitative scoring (percentage)
were determined. Digested material, crustaceans, sediment and mollusks were the principal items of the diet. Echinoderms,
annelids, plants, and fishes were also notable prey items, and other food categories (foraminiferans, cnidarians, worms and
bryozoans) occurred in low percentages. A non-significant difference was found in many items during seasonal analysis, i.e.
plants, foraminiferans, cnidarians, bryozoans and digested material were present at highest percentages during summer and
autumn, while crustaceans and echinoderms were consumed in larger amounts during the spring and winter. Males and females
consumed a similar diet, although ovigerous females showed a greater tendency to feed on items with soft tissues (fish, squid,
shrimp). Juveniles fed more on sedentary and calcareous items than did adults, showing a significant tendency to reduce consumption
of foraminiferans, annelids, bryozoans, echinoderms and sediment as the animal increased in size, accompanied by an elevation
in the consumption of plants, crustaceans and fish. These crabs are opportunistic predators with a preference for crustaceans
and mollusks that is correlated with the availability of prey and the ontogenetic phase of the predator.
Received: 21 January 2000 / Accepted: 2 October 2000 相似文献
544.
Jasmonic acid treatment and mammalian herbivory differentially affect chemical defenses and growth of wild mustard (Brassica kaber) 总被引:2,自引:0,他引:2
Summary. Jasmonic acid (JA) is a wound-related hormone found in most plants that, when applied exogenously, can induce increases in
levels of chemical defenses in patterns similar to those induced by mechanical damage or insect feeding. Relative to responses
to insect and pathogen attack, chemical responses of herbaceous plants to mammalian herbivore attack have been little studied.
In a field experiment, we compared the effects of JA treatment and naturally occurring mammalian herbivory on the expression
of trypsin inhibitors, glucosinolates, peroxidase activity and growth of wild mustard (Brassica kaber). Exogenous JA significantly increased trypsin inhibitor activity and glucosinolate concentration, and moderately increased
peroxidase activity in the eighth true leaves of five-week-old plants, relative to untreated controls. In contrast, levels
of these chemical defenses in the eighth true leaves or in regrowth foliage of plants that had ∼80% of their leaf area removed
by groundhogs (Marmota monax) did not differ from that in undamaged and untreated controls. Although exogenous JA significantly elevated levels of chemical
defenses, it did not affect height of plants through the season and only slightly reduced time to first flower. Groundhog
herbivory significantly reduced height and delayed or abolished flowering, but these effects were not substantial unless coupled
with apical meristem removal. We hypothesize that the lack of effect of groundhog herbivory on chemical defenses may be due
in part to the speed and pattern of leaf area removal by groundhogs, or physiological constraints caused by leaf area loss.
Despite having no effect on chemical defense production, leaf area loss by groundhogs was more costly to growth and fitness
than the effects of JA application in this study, but only substantially so if coupled with apical meristem removal. We suggest
that in general, costs of defense production in plants are likely to be minimal when compared to the risk of losing large
amounts of leaf area or primary meristematic tissue. Thus, if they are effective at deterring herbivory, the benefits of inducible
defense production likely outweigh the costs in most cases.
Received 20 December 2000; accepted 3 May 2001 相似文献
545.
M. Zimmer J. P. Danko S. C. Pennings A. R. Danford A. Ziegler R. F. Uglow T. H. Carefoot 《Marine Biology》2001,138(5):955-963
Three isopod species (Crustacea: Isopoda), commonly found in the intertidal and supratidal zones of the North American Pacific
coast, were studied with respect to symbiotic microbiota in their midgut glands (hepatopancreas). Ligia pallasii (Oniscidea: Ligiidae) contained high numbers of microbial symbionts in its hepatopancreatic caeca. Numbers of endosymbionts
were strongly reduced by ingestion of antibiotics. By contrast, the hepatopancreas of Idotea wosnesenskii (Valvifera: Idoteidae) and Gnorimosphaeroma oregonense (Sphaeromatidea: Sphaeromatidae) did not contain any microbiota. Results of feeding experiments suggest that microbial endosymbionts
contribute to digestive processes in L. pallasii, the most terrestrial of the three isopods that we studied. The acquisition of digestion-enhancing endosymbionts may have
been an important evolutionary step allowing isopods to colonize terrestrial habitats where relatively indigestible leaf litter
is the primary food source. By contrast, the ability to digest phenolic compounds was most developed in one of the more marine
species, suggesting that this trait may have evolved independently in isopod species that consume a phenolic-rich diet, whether
in marine habitats or on land.
Received: 28 August 2000 / Accepted: 8 December 2000 相似文献
546.
We determined the nuclear 18S rRNA sequences for 41 species of octocorals and used these to address the validity of the historical
ordinal divisions and the current subordinal divisions within the subclass Octocorallia. We also explored the phylogenetic
affinities of the species Dendrobrachia paucispina, which was originally classified in the order Antipatharia (subclass Ceriantipatharia) although polyp structure indicates
it belongs in the subclass Octocorallia. Trees constructed using maximum likelihood techniques are incongruent with the current
and historical taxonomy of the Octocorallia. There appeared to be three major clades of octocorals. The first clade included
most, but not all, pennatulaceans as a monophyletic group. The second clade contained 21 species, representing all major octocoral
groups other than pennatulaceans. The third clade contained members from three suborders of the Alcyonacea and one member
of the Pennatulacea. These data could not be used to distinguish the branching order of the three major clades. The species
D. paucispina had a close affinity with the genera Corallium and Paragorgia (Alcyonacea: Scleraxonia), although its morphology suggests it is more similar to the genus Chrysogorgia (Alcyonacea: Calcaxonia). The morphological character of dimorphism (the presence of both autozooids and siphonozooids within
a single colony) corresponded loosely with the topology of the most likely trees, and a single origin of dimorphism could
not be rejected. Despite sampling from the majority of families within the Octocorallia, many of the relationships within
this group remain ambiguous.
Received: 16 June 2000 / Accepted: 14 September 2000 相似文献
547.
One-day-old anarchistic (selected for successful worker reproduction) and wild-type honey-bee workers were introduced into queenright colonies of honey-bees of two treatments. In treatment 1, all eggs and larvae were offspring of queens from an anarchistic line. In treatment 2, all eggs and larvae were offspring of wild-type queens. In both treatments, adult workers were wild type. This experimental arrangement was used to test the importance of larval genotype on ovary activation in young adult workers. After 12 days, the introduced bees were dissected to determine the frequency of ovary activation. In those colonies provided with wild-type brood, 0% of introduced wild-type bees and 16% of anarchistic bees had activated ovaries. In those colonies provided with anarchistic brood, 13% of introduced wild-type bees and 41% of anarchistic bees had activated ovaries. These results strongly support the hypothesis that selection for high levels of worker reproduction in anarchistic stocks has reduced the amount or composition of brood pheromones produced by larvae that normally signal workers to refrain from reproduction. They also suggest that anarchistic workers have a higher threshold for these signals than wild-type bees. 相似文献
548.
549.
550.
J. F. Jasonsmith B. C. T. Macdonald I. White 《Environmental monitoring and assessment》2017,189(4):188
Wybong Creek discharges salts into the agriculturally and industrially important Hunter River in New South Wales, Australia. Abrupt increases in salinity occur periodically in the mid-Wybong Creek catchment. In order to understand the processes which cause these abrupt increases, changes in surface and groundwater were investigated. It is shown that salinity increases can be attributed to highly discrete groundwater discharge directly into the river from below. Hourly electrical conductivity data measured in the river showed regular, diurnal electrical conductivity fluctuations of up to 350 μS cm?1. These fluctuations could not be attributed to barometric pressure, temperature, or evapotranspiration. Instead, a similar periodicity in surface water electrical conductivity and groundwater height in nearby groundwater wells was found. Fluctuations were of similar periodicity to the orthotides which cause fluctuations in surface water height and are induced by Earth tides. The geology in the mid-catchment area indicates conditions are optimal for Earth tides to impact groundwater. The reporting of orthotidal changes in water chemistry in this article is believed to be the first of its kind in the scientific literature, with the large fluctuations noted having important implications for water monitoring and management in the catchment. Further research investigating Earth-tide-induced phases of groundwater heights will better constrain the relationships between surface water chemistry and groundwater height. 相似文献