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971.
Thimerosal (ethylmercurithiosalicylic acid), an ethylmercury (EtHg)-releasing compound (49.55% mercury (Hg)), was used in a range of medical products for more than 70 years. Of particular recent concern, routine administering of Thimerosal-containing biologics/childhood vaccines have become significant sources of Hg exposure for some fetuses/infants. This study was undertaken to investigate cellular damage among in vitro human neuronal (SH-SY-5Y neuroblastoma and 1321N1 astrocytoma) and fetal (nontransformed) model systems using cell vitality assays and microscope-based digital image capture techniques to assess potential damage induced by Thimerosal and other metal compounds (aluminum (Al) sulfate, lead (Pb)(II) acetate, methylmercury (MeHg) hydroxide, and mercury (Hg)(II) chloride) where the cation was reported to exert adverse effects on developing cells. Thimerosal-associated cellular damage was also evaluated for similarity to pathophysiological findings observed in patients diagnosed with autistic disorders (ADs). Thimerosal-induced cellular damage as evidenced by concentration- and time-dependent mitochondrial damage, reduced oxidative–reduction activity, cellular degeneration, and cell death in the in vitro human neuronal and fetal model systems studied. Thimerosal at low nanomolar (nM) concentrations induced significant cellular toxicity in human neuronal and fetal cells. Thimerosal-induced cytoxicity is similar to that observed in AD pathophysiologic studies. Thimerosal was found to be significantly more toxic than the other metal compounds examined. Future studies need to be conducted to evaluate additional mechanisms underlying Thimerosal-induced cellular damage and assess potential co-exposures to other compounds that may increase or decrease Thimerosal-mediated toxicity. 相似文献
972.
Kevin J. Flynn 《Chemistry and Ecology》2013,29(3):109-116
Despite the fact that coccolithophorids such as Emiliania huxleyi are suspected to play an important role in carbon-cycling, there are few data from which to deduce how these organisms may respond to CO2-induced global warming. the nitrogen and phosphorus nutrient physiology of these organisms, together with its interaction with photosynthesis, needs to be studied especially in connection with the selection for coccolith forming individuals and the quantity and quality of the CaCO3 deposited in the coccoliths. Without such data, it will not be possible to model the contributions that these microalgae may play in arresting the increase in levels of atmospheric CO2. 相似文献
973.
Earl D. McCoy Katherine A. Basiotis Kevin M. Connor Henry R. Mushinsky 《Behavioral ecology and sociobiology》2013,67(5):815-821
Habitat selection requires choice, which differentiates it from habitat use, and choice, in turn, is dependent upon the responses of organisms to the environmental, social, and other cues that they perceive. Habitat selection by the gopher tortoise (Gopherus polyphemus) was investigated by translocating tortoises and monitoring their movements within two sites in central Florida. The first site supported a stable preponderance of high-quality habitat, and tortoises avoided areas with a dense tree canopy cover caused by fire exclusion. The second site was badly invaded by an introduced weed, and tortoises avoided areas where the weed had formed a dense monoculture. At both sites, individuals appeared to be responding to visual cues to avoid areas that were relatively dark. In landscapes with relatively large amounts of high-quality habitat, this avoidance behavior serves the gopher tortoise well by keeping individuals within the dominant habitat type. In degraded areas, high-quality habitat often becomes increasingly uncommon, and the avoidance behavior exhibited by the tortoises will result in individuals becoming confined to small patches, causing a significant reduction in fitness and hence questioning their long-term survival in such areas. The results from our study show that in order to maintain viable tortoise populations in areas increasingly subjected to human fragmentation and degradation, it is crucial not only to suppress tree canopy cover continually and prevent invasion by exotic weeds, but also to be mindful that the avoidance behavior of the gopher tortoise could prevent individuals from fully occupying a high-quality habitat in response to restoration and management efforts. 相似文献
974.
The demand for traditional medicinal plants and products in South Africa has created an extensive cross-border industry involving thousands of harvesters and traders. The market values of individual taxa vary considerably. Pricing structures fluctuate between markets and over time as the cost of harvesting species varies depending on a gatherer's access to the resources and the proximity of markets to the harvesting sites. This paper estimates trade values, describes the prices paid for 22 plant resources, investigates pricing structures relative to the mass/volume sold and the factors that influence the market price for plants. There is an inverse and disproportionate relationship between the price per kilogram (R/kg) and mass of the product sold. The smaller the quantity sold, the higher the R/kg sale values are relative to sales of larger quantities. This relationship is evident in different plant part types (e.g. bark and bulbs), species and markets (shops and street markets). Given the high mass sold relative to the price, bulbs, like bark, have the lowest R/kg values compared to other products like roots, fruits and leaves. The prices paid for heavier/denser species is thus disproportionate to the mass sold. If the relative values are used as an indicator of plant vulnerability (assuming high values indicate greater vulnerability), then bias is created in favour of 'lighter' and less dense plant parts typically sold in small quantities because of the nature of the plant part and the manner in which it is marketed and required by customers. 相似文献
975.
Monitoring the population trends of multiple animal species at a landscape scale is prohibitively expensive. However, advances in survey design, statistical methods, and the ability to estimate species presence on the basis of detection-nondetection data have greatly increased the feasibility of species-level monitoring. For example, recent advances in monitoring make use of detection-nondetection data that are relatively inexpensive to acquire, historical survey data, and new techniques in genetic evaluation. The ability to use indirect measures of presence for some species greatly increases monitoring efficiency and reduces survey costs. After adjusting for false absences, the proportion of sample units in a landscape where a species is detected (occupancy) is a logical state variable to monitor. Occupancy monitoring can be based on real-time observation of a species at a survey site or on evidence that the species was at the survey location sometime in the recent past. Temporal and spatial patterns in occupancy data are related to changes in animal abundance and provide insights into the probability of a species' persistence. However, even with the efficiencies gained when occupancy is the monitored state variable, the task of species-level monitoring remains daunting due to the large number of species. We propose that a small number of species be monitored on the basis of specific management objectives, their functional role in an ecosystem, their sensitivity to environmental changes likely to occur in the area, or their conservation importance. 相似文献
976.
977.
William S. Lynn Francisco Santiago-Ávila Joann Lindenmayer John Hadidian Arian Wallach Barbara J. King 《Conservation biology》2019,33(4):769-776
Some conservationists believe that free-ranging cats pose an enormous risk to biodiversity and public health and therefore should be eliminated from the landscape by any means necessary. They further claim that those who question the science or ethics behind their arguments are science deniers (merchants of doubt) seeking to mislead the public. As much as we share a commitment to conservation of biodiversity and wild nature, we believe these ideas are wrong and fuel an unwarranted moral panic over cats. Those who question the ecological or epidemiological status of cats are not science deniers, and it is a false analogy to compare them with corporate and right-wing special interests that perpetrate disinformation campaigns over issues, such as smoking and climate change. There are good conservation and public-health reasons and evidence to be skeptical that free-ranging cats constitute a disaster for biodiversity and human health in all circumstances. Further, there are significant and largely unaddressed ethical and policy issues (e.g., the ethics and efficacy of lethal management) relative to how people ought to value and coexist with cats and native wildlife. Society is better served by a collaborative approach to produce better scientific and ethical knowledge about free-ranging cats. 相似文献
978.
Matthew B. Toomey Michael W. Butler Melissa G. Meadows Lisa A. Taylor H. Bobby Fokidis Kevin J. McGraw 《Behavioral ecology and sociobiology》2010,64(6):1047-1055
The glossy sheen of healthy hair is an ideal of human beauty; however, glossiness has never been quantified in the context
of non-human animal signaling. Glossiness, the specular reflectance characteristic of polished surfaces, has the potential
to act as a signal of quality because it depends upon material integrity and cleanliness. Here, we undertook two studies of
glossiness in avian plumage to determine (a) the repeatability of a recently developed measure of glossiness, (b) the relationship
between glossiness and conventional measures of coloration, and (c) how glossiness is associated with quality signaling. Using
museum specimens of three North American bird species with glossy plumage (red-winged blackbird, Agelaius phoeniceus; great-tailed grackle, Quiscalus mexicanus; Chihuahuan raven, Corvus cryptoleucus), we found that the glossiness measure was highly repeatable for all species and was significantly correlated with plumage
coloration (e.g., chroma, brightness) in male great-tailed grackles. We then used wild-caught grackles to examine sexual dimorphism
in plumage glossiness and its correlation to a potentially sexually selected trait in this species, male tail length. We found
that males were significantly glossier than females and that male, but not female, glossiness correlated positively with tail
length. This study provides a repeatable method to measure glossiness and highlights its potential as a signal of individual
quality in animals. 相似文献
979.
Daniel A. Warner Kevin L. Woo Daniel A. Van Dyk Christopher S. Evans Richard Shine 《Behavioral ecology and sociobiology》2010,64(5):803-813
The complex ritualized displays of males in many territorial species suggest that selection has shaped male behaviors in ways
that affect fitness. In this study, we evaluated the link between display behavior during male–male interactions and reproductive
success in the Australian jacky dragon (Amphibolurus muricatus), a lizard species that uses a complex series of movement patterns for communication. We quantified variation in male display
behaviors by using video playback experiments in the laboratory, and subsequently assessed variation in male reproductive
success by paternity analyses of offspring. Because the lizards used in this study came from eggs incubated under three thermal
environments, we also could evaluate the impact of developmental temperature on adult behavior and reproductive success. Incubation
temperature had a strong effect on male reproductive success; males produced under intermediate temperatures sired more offspring
than those produced under extreme developmental temperatures. However, incubation temperature did not affect male display
behavior, nor was male behavior associated with reproductive success. Our findings do not support the common assumption that
display behaviors used during male–male interactions affect reproductive success. 相似文献
980.