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301.
Toxic Burials: The Final Insult 总被引:1,自引:0,他引:1
Johnny P. Stowe Jr. Elise Vernon Schmidt † Deborah Green‡# 《Conservation biology》2001,15(6):1817-1819
302.
Two laboratory experiments were conducted on Ophiocoma echinata (Lamarck, 1816) collected from Missouri Key, Florida, USA, to ascertain the effects of arm regeneration on energy storage
and gonad production. In each experiment individuals were divided into non-regenerating (all arms intact) and regenerating
(three arms autotomized) groups and maintained together in a re-circulating seawater system for 2 mo. In Experiment 1, individuals
were fed once a week, and in Experiment 2 once every 2 wk. The amount of food energy required for maintenance was estimated
to be 0.172 kJ d−1. The lower feeding level (Experiment 2) was below maintenance ration and both groups lost material relative to an initial
group. At the higher feeding level (Experiment 1), regeneration of three arms resulted in less storage of organic material,
mainly lipid in the stomach, and less gonad production. Thus, regeneration may reduce energy reserves and reproductive output.
Received: 23 April 1998 / Accepted: 11 January 1999 相似文献
303.
304.
Christian A. Chisholm Fotini Vavelidis Mark A. Lovell Lawrence Sweetman Charles R. Roe Diane S. Roe Frank E. Frerman William G. Wilson 《黑龙江环境通报》2001,21(10):856-859
We report the occurrence of multiple acyl-CoA dehydrogenase deficiency (MADD) in two consecutive pregnancies in a young, Caucasian, non-consanguineous couple. In the first pregnancy, the maternal serum α-fetoprotein was elevated. A sonogram showed growth delay, cystic renal disease, and oligohydramnios; the parents decided to terminate the pregnancy. Postmortem examination confirmed the cystic renal disease and showed hepatic steatosis, raising the suspicion of a metabolic disorder. The diagnosis of MADD was made by immunoblot studies on cultured fibroblasts. In the subsequent pregnancy, a sonogram at 15 weeks' gestation showed an early growth delay but normal kidneys. The maternal serum and amniotic fluid concentrations of α-fetoprotein were elevated, and the amniotic fluid acylcarnitine profile was consistent with MADD. In vitro metabolic studies on cultured amniocytes confirmed the diagnosis. A follow-up sonogram showed cystic renal changes. These cases provide additional information regarding the evolution of renal changes in affected fetuses and show a relationship with elevated α-fetoprotein, which may be useful in counseling the couple at risk. MADD should be considered in the differential diagnosis of elevated α-fetoprotein and cystic renal disease. Early growth delay may be an additional feature. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
305.
J. Gary Lawrence 《Local Environment》1996,1(3):317-322
306.
307.
Yong Tang Yuanlong Huang Ling Li Hong Chen Jianmin Chen Xin Yang Song Gao Deborah S. Gross 《环境科学学报(英文版)》2014,26(12):2412-2422
Physical and chemical properties of ambient aerosols at the single particle level were studied in Shanghai from December 22 to 28, 2009. A Cavity-Ring-Down Aerosol Extinction Spectrometer(CRD-AES) and a nephelometer were deployed to measure aerosol light extinction and scattering properties, respectively. An Aerosol Time-of-Flight Mass Spectrometer(ATOFMS)was used to detect single particle sizes and chemical composition. Seven particle types were detected. Air parcels arrived at the sampling site from the vicinity of Shanghai until mid-day of December 25, when they started to originate from North China. The aerosol extinction,scattering, and absorption coefficients all dropped sharply when this cold, clean air arrived.Aerosol particles changed from a highly aged type before this meteorological shift to a relatively fresh type afterwards. The aerosol optical properties were dependent on the wind direction.Aerosols with high extinction coefficient and scattering Angstrom exponent(SAE) were observed when the wind blew from the west and northwest, indicating that they were predominantly fine particles. Nitrate and ammonium correlated most strongly with the change in aerosol optical properties. In the elemental carbon/organic carbon(ECOC) particle type, the diurnal trends of single scattering albedo(SSA) and elemental carbon(EC) signal intensity had a negative correlation. We also found a negative correlation(r =-0.87) between high mass-OC particle number fraction and the SSA in a relatively clean period, suggesting that particulate aromatic components might play an important role in light absorption in urban areas. 相似文献
308.
The net benefits of mutualism depend directly on the costs and effectiveness of mutualistic services and indirectly on the interactions that affect those services. We examined interactions among Cordia alliodora myrmecophytic trees, their symbiotic ants Azteca pittieri, coccoid hemipterans, and foliar herbivores in two Neotropical dry forests. The tree makes two investments in symbiotic ants: it supplies nesting space, as domatia, and it provides phloem to coccoids, which then produce honeydew that is consumed by ants. Although higher densities of coccoids should have higher direct costs for trees, we asked whether higher densities of coccoids can also have higher indirect benefits for trees by increasing the effectiveness of ant defense against foliar herbivores. We found that trees benefited from ant defense against herbivores. Ants defended trees effectively only when colonies reached high densities within trees, and ant and coccoid densities within trees were strongly positively correlated. The benefits of reduced foliar herbivory by larger ant colonies were therefore indirectly controlled by the number of coccoids. Coccoid honeydew supply also affected per capita ant aggression against tree herbivores. Ants experimentally fed a carbohydrate-rich diet, analogous to sugar obtained from coccoids, were more aggressive against caterpillars per capita than ants fed a carbohydrate-poor diet. Ant defense was more effective on more valuable and vulnerable young leaves than on older leaves. Young domatia, associated with young leaves, contained higher coccoid densities than older domatia, which suggests that coccoids may also drive spatially favorable ant defense of the tree. If higher investments by one mutualistic partner are tied to higher benefits received from the other, there may be positive feedback between partners that will stabilize the mutualism. These results suggest that higher investment by trees in coccoids leads to more effective defense by ants against the tree's foliar herbivores. 相似文献
309.
Europe has a wealth of community forest arrangements. This paper aims to transcend the diversity of locally specific terms and forms, to highlight the value of considering them inclusively. Building on methods to make sense of diversity, we use reflexive grounded inquiry in fifteen cases in Italy, Scotland, Slovenia and Sweden. Within four dimensions (forest, community, relationships between them, and relationships with wider society), we identify 43 subdimensions to describe them collectively. Our approach shows how European arrangements contribute to wider discourses of collective natural resource management. Both tradition and innovation in Europe inform options for environmental governance. Arrangements challenge the distinction between ‘communities of place’ and ‘communities of interest’, with implications for social and environmental justice. They exemplify multilevel environmental governance through both vertical and horizontal connections. Emerging from long histories of political and environmental pressures, they have a role in enhancing society’s connection with nature and adaptive capacity.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01377-x) contains supplementary material, which is available to authorised users. 相似文献
310.