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921.
Workers never mate in the large majority of ants, and they have usually lost the spermatheca, an organ specialized for long-term
storage of sperm. Such ‘non-sexual’ workers are restricted to laying unfertilized eggs that give rise to males, and they cannot
compete with the queens for the production of female offspring. In sharp contrast, workers in 200–300 species from phylogenetically
basal subfamilies can reproduce sexually (‘gamergates’) because they retain a functional spermatheca like the queens. Importantly,
‘non-sexual’ workers in closely related species have a vestigial spermatheca. In this study, we compared the reservoir epithelium
of ‘sexual’ workers to that of congeneric queens and ‘non-sexual’ workers using 21 species of Amblyoponinae, Ponerinae and
Ectatomminae. We show that a pronounced thickening of the epithelium near the opening of the sperm duct is strictly associated
with sexual reproduction in both castes. This is unlike ‘non-sexual’ workers in which this epithelium is always very thin,
with few organelles; but all other structures remain intact. We discuss this evolutionary degeneration of the spermatheca
and how it relates to behavioural or physiological modifications linked to mating. Our results help understand the loss of
sexual reproduction by ant workers, a critical step in the extreme specialization of their phenotype. 相似文献
922.
How is behaviour organised across sensory modalities? Specifically, we ask concerning the fruit fly Drosophila melanogaster how visual context affects olfactory learning and recall and whether information about visual context is getting integrated into olfactory memory. We find that changing visual context between training and test does not deteriorate olfactory memory scores, suggesting that these olfactory memories can drive behaviour despite a mismatch of visual context between training and test. Rather, both the establishment and the recall of olfactory memory are generally facilitated by light. In a follow-up experiment, we find no evidence for learning about combinations of odours and visual context as predictors for reinforcement even after explicit training in a so-called biconditional discrimination task. Thus, a ‘true’ interaction between visual and olfactory modalities is not evident; instead, light seems to influence olfactory learning and recall unspecifically, for example by altering motor activity, alertness or olfactory acuity. 相似文献
923.
Active pharmaceutical ingredients (APIs) from medications can enter the environment as trace contaminants, at individual concentrations generally below a part per billion (microg/L). APIs enter the environment primarily via the discharge of raw and treated sewage. Residues of unmetabolized APIs from parenteral and enteral drugs are excreted in feces and urine, and topically applied medications are washed from skin during bathing. These trace residues may pose risks for aquatic life and cause concern with regard to subsequent human exposure. APIs also enter the environment from the disposal of unwanted medications directly to sewers and trash. The relative significance of this route compared with excretion and bathing is poorly understood and has been subject to much speculation. Two major aspects of uncertainty exist: the percentage of any particular API in the environment originating from disposal is unknown, and disposal undoubtedly occurs from a variety of dispersed sources. Sources of disposal, along with the types and quantities of APIs resulting from each source, are important to understand so that effective pollution prevention approaches can be designed and implemented. Accumulation of leftover, unwanted drugs poses three major concerns: (i) APIs disposed to sewage or trash compose a diverse source of potential chemical stressors in the environment. (ii) Accumulated drugs represent increased potential for drug diversion, with its attendant risks of unintentional poisonings and abuse. (iii) Leftover drugs represent wasted healthcare resources and lost opportunities for medical treatment. This paper has four major purposes: (1) Define the processes, actions, and behaviors that control and drive the consumption, accumulation, and need for disposal of pharmaceuticals. (2) Provide an overview of the diverse locations where drugs are used and accumulate. (3) Present a summary of the first cataloging of APIs disposed by a defined subpopulation. (4) Identify opportunities for pollution prevention and source reduction. 相似文献
924.
Protected areas (PAs) are often implemented without consideration of already existing PAs, which is likely to cause an overrepresentation of certain biophysical conditions. We assessed the representativeness of the current PA network with regard to the world's biophysical conditions to highlight which conditions are underprotected and where these conditions are located. We overlaid terrestrial and marine PAs with information on biophysical conditions (e.g., temperature, precipitation, and elevation) and then quantified the percentage of area covered by the PA network. For 1 variable at a time in the terrestrial realm, high temperature, low precipitation, and medium and very high elevation were underrepresented. For the marine realm, low and medium sea surface temperature (SST), medium and high sea surface salinity (SSS), and the deep sea were underrepresented. Overall, protection was evenly distributed for elevation across the terrestrial realm and SST across the marine realm. For 2 variables at a time, cold and very dry terrestrial environments had mostly low protection, which was also the case for low SST and low and medium SSS across most depths for marine environments. Low protection occurred mostly in the Sahara and the Arabian Peninsula for the terrestrial realm and along the Tropic of Capricorn and toward the poles for the marine realm. Although biodiversity measures are of prime importance for the design of PA networks, highlighting biophysical gaps in current PAs adds a frequently overlooked perspective. These gaps may weaken the potential of PAs to conserve biodiversity. Thus, our results may provide useful insights for researchers, practitioners, and policy makers to establish a more comprehensive global PA network. 相似文献
925.
Cheviron Nathalie Grondin Virginie Marrauld Christelle Poiroux Françoise Bertrand Isabelle Abadie Josiane Pandard Pascal Riah-Anglet Wassila Dubois Caroline Malý Stanislav Marques Catarina R. Asenjo Inmaculada Valverde Alonso Alejandro Díaz Domingo Marquina Mougin Christian 《Environmental science and pollution research international》2022,29(20):29348-29357
Environmental Science and Pollution Research - The evaluation of soil quality requires the use of robust methods to assess biologically based indicators. Among them, enzyme activities are used for... 相似文献
926.
Daniel-Mkpume Cynthia Chikodi Ahaiwe Rachel Chinwendu Ifenatuorah Chigozie Lucas Ike-Eze Ikechukwu Christian Ezema Aigbodion Victor Sunday Egoigwe Sochima Vincent Okonkwo Emenike George 《Journal of Material Cycles and Waste Management》2022,24(2):680-691
Journal of Material Cycles and Waste Management - This study contributes towards showing the potential end-of-life application of common wastes namely: Waste Toner powder (WTP) and African star... 相似文献
927.
Rudolf Brenneis Hubertus Wichmann Regina Sprenger Astrid Eickhoff Ralf Bock Tina Dettmer Burkhard Baeck Christian Reger Müfit Bahadir 《Environmental Sciences Europe》2006,18(2):95-101
Aims and Scope
Compared to mineral oil products, cooling lubricants based on fatty acid esters have technological advantages. Moreover, they are more environmentally compatible and make a contribution to a sustainable economy. Nevertheless, they are rarely applied in practice, because of their comparably high price, that is based on raw-material and synthesis costs. Alternatives concerning raw-materials and synthesis pathways are considered and properties of resulting ester products are compared.Methods
The investigations aimed at three fatty acid-2-ethyl-hexylesters that were synthesized in an enzymatic-catalytic routine based on peanut oil, suet, and waste edible fat and at esters that were conventionally produced from animal and plant fats and 2-ethyl-1-hexanol. Physical properties, fatty acid patterns, contents of free fatty acids, as well as oxidative and hydrolytic stabilities were determined. Thermolysis experiments were performed.Results
The physical properties of the seven esters, density, viscosity, pourpoint, and flash point, were comparable and gave reason for the assumption, that the products could be used as basis oils in lubricant formulations. Hydrolysis stabilities of the esters were high and thermal stress did not point at high potential of hazardous compounds formation. Especially the enzymatic-catalytically produced esters showed deficits concerning oxidation stabilities and free fatty acid contents.Outlook
For practice it will be necessary to define minimum qualities for raw-materials and resulting ester oils to be used as lubricant basis oils. Moreover, processes have to be developed, that yield high quality ester products from waste edible and animal fats without loosing the advantage of low-cost raw-materials by high production and refinement costs. Surely, one contribution is the further development of the energy-saving enzymtic alcoholysis for ester production. 相似文献928.
Touma JS Isakov V Ching J Seigneur C 《Journal of the Air & Waste Management Association (1995)》2006,56(5):547-558
The current requirements and status of air quality modeling of hazardous pollutants are reviewed. Many applications require the ability to predict the local impacts from industrial sources or large roadways as needed for community health characterization and evaluating environmental justice concerns. Such local-scale modeling assessments can be performed by using Gaussian dispersion models. However, these models have a limited ability to handle chemical transformations. A new generation of Eulerian grid-based models is now capable of comprehensively treating transport and chemical transformations of air toxics. However, they typically have coarse spatial resolution, and their computational requirements increase dramatically with finer spatial resolution. The authors present and discuss possible advanced approaches that can combine the grid-based models with local-scale information. 相似文献
929.
Seigneur C Lohman K Vijayaraghavan K Jansen J Levin L 《Journal of the Air & Waste Management Association (1995)》2006,56(6):743-751
Two mathematical models of the atmospheric fate and transport of mercury (Hg), an Eulerian grid-based model and a Gaussian plume model, are used to calculate the atmospheric deposition of Hg in the vicinity (i.e., within 50 km) of five coal-fired power plants. The former is applied using two different horizontal resolutions: coarse (84 km) and fine (16.7 km). More than 96% of the power plant Hg emissions are calculated with the plume model to be transported beyond 50 km from the plants. The grid-based model predicts a lower fraction to be transported beyond 50 km: >91% with a coarse resolution and >95% with a fine resolution. The contribution of the power plant emissions to total Hg deposition within a radius of 50 km from the plants is calculated to be <8% with the plume model, <14% with the Eulerian model with a coarse resolution, and <10% with the Eulerian model with a fine resolution. The Eulerian grid-based model predicts greater local impacts than the plume model because of artificially enhanced vertical dispersion; the former predicts about twice as much Hg deposition as the latter when the area considered is commensurate with the resolution of the grid-based model. If one compares the local impacts for an area that is significantly less than the grid-based model resolution, then the grid-based model may predict lower local deposition than the plume model, because two compensating errors affect the results obtained with the grid-based model: initial dilution of the power plant emissions within one or more grid cells and enhanced vertical mixing to the ground. 相似文献
930.
Cadmium levels in Europe: implications for human health 总被引:5,自引:0,他引:5
Jilang Pan Jane A. Plant Nikolaos Voulvoulis Christopher J. Oates Christian Ihlenfeld 《Environmental geochemistry and health》2010,32(1):1-12
In this study we used the Forum of European Geological Surveys geochemical baseline data to examine the distribution of cadmium
(Cd) in Europe, with a particular reference to the international soil and water guideline values. The highest cadmium levels
were found to occur in topsoil and to follow closely the distribution of P2O5, suggesting that the contamination was from the use of rock phosphate fertilizer in intensive arable agriculture. In terms
of human health impacts, food (up to several hundred μg/day) was found as the only major route of exposure to Cd for the non-smoking
general population. It appeared that low levels of chronic exposure to Cd resulted in completely different human health impacts
than those high levels that had caused the ‘itai–itai’ disease. Some correlations were suggested between cadmium levels and
the age-adjusted prostate or breast cancer rates distributed in the European countries under study. 相似文献