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1.
2.
Chemical defense and evolutionary trends in biosynthetic capacity among dorid nudibranchs (Mollusca: Gastropoda: Opisthobranchia) 总被引:5,自引:0,他引:5
Summary. An evolutionary scenario incorporating recent advances in phylogenetic research begins with an opisthobranch-pulmonate common
ancestor that was herbivorous and had some diet-derived chemical defense. The Nudibranchia and their closest relatives, the
Notaspidea, form a lineage the ancestors of which had switched to feeding upon sponges and deriving protection from metabolites
contained in them. Subsequently there have been repeated shifts in food and defensive metabolites, and trends are evident
in the ability to detoxify, sequester and utilize metabolites from food, as well as to synthesize defensive compounds de novo. The Notaspidea display a minor adaptive radiation that foreshadows a more extensive one in the various lineages of nudibranchs.
This review emphasizes changes that have occurred within the Holohepatica, or dorid nudibranchs (order Doridacea). Their sister-group,
the Cladohepatica, consists of three other orders, Dendronotacea, Arminacea, and Aeolidiacea, in which there has been a shift
from sponges to Cnidaria as food. The Dendronotacea often feed upon Octocorallia, which combine spicules, chemical defense,
and stinging capsules and thereby suggest a transition from feeding on sponges. A previous diet of Octocorallia is suggested
by the defensive use of prostaglandins in the dendronotacean Tethys fimbria, which eats crustaceans. A shift to bryozoans in some Arminacea is accompanied by use of different metabolites. Dorid nudibranchs
evidently began as sponge-feeders, but some lineages have shifted to a variety of other food organisms, and others have specialized
in the kind of sponges they feed on and how they do it. There have been shifts to bryozoans (Ectoprocta) and ascidians (Chordata:
Urochordata) that track metabolites rather than the taxonomy of the food. There is a crude correlation between the genealogy
and the defensive metabolites of the sponge-feeding dorids. De novo synthesis is well documented in this order and the metabolites are appropriately positioned so as to have an adaptive effect.
The hypothesis that the capacity for de novo synthesis was acquired by gene transfer across lineages is rejected, partly on the basis of different chirality of metabolites
in the nudibranchs and their food organisms. Instead it is proposed that there has been a preadaptive phase followed by evolution
in a retrosynthetic mode, with selection favoring enzymes that enhance the yield of end products that are already present
in the food.
Received 5 February 1999; accepted 26 July 1999 相似文献
3.
Victoria?SorokerEmail author Dennis?R.?Nelson Ornit?Bahar Saadia?Reneh Sarah?Yablonski Eric?Palevsky 《Chemoecology》2003,13(4):163-168
Summary. Broad mite, Polyphagotarsonemus latus (Acari:
Tarsonemidae) exhibits a specific phoretic relationship with
whiteflies. Under field conditions most broad mites, caught
in sticky traps, are attached to whiteflies. Under laboratory
conditions, attachment occurs equally well in the dark and
light. Mites do not differentiate between the sexes of their
phoretic host Bemisia tabaci. However, mite attachment to
B. tabaci is greatly diminished by washing the host with
various organic solvents, chloroform in particular. The
effect of whitefly waxy particles on broad mite behavior was
studied using wax from the whitefly Aleyrodes singularis
and from the mealybug Planococcus citri. Broad mites were
not only attracted specifically to the A. singularis waxy
particles-treated leaf areas but were also attached to leaf
trichomes in this area. The results of this study suggests the
importance of olfactory cues from the whitefly waxy particles
in the recognition process of the phoretic host and/or
the induction of the attachment behavior to whitefly legs or
leaf trichomes. 相似文献
4.
刘玉波 《辽宁城乡环境科技》2013,(6):53-55
结合我国国情,对绿色建筑的基本概念和要达到的目标进行了分析。综合可持续发展评价体系以及我国目前在绿色建筑方面的发展进程,提出全面推进绿色建筑,完善建筑业可持续发展体系的措施建议。 相似文献
5.
Industry Response to the Challenge of Sustainability: The Case of the Canadian Nonferrous Mining Sector 总被引:3,自引:0,他引:3
Luis E. Sánchez 《Environmental management》1998,22(4):521-531
/ The paper investigates how the Canadian nonferrous sector is tackling the challenge of sustainable development. Although there is no consensus as to what sustainable development means in practice for management in the sector, at least three dimensions must be taken into account: (1) metals are recyclable, the availability of this resource is not a concern for the foreseeable future; (2) the need to minimize environmental impacts of metals exploration, extraction, transformation, consumption, and recycling; and (3) production activities should not be socially or culturally disruptive. The nonferrous mining industry faces several environmental problems. Some of the most significant are acid mine drainage, sulfur emissions, recycling, and metals toxicity. The industry has developed a number of responses to address these specific concerns as well as other more general challenges. Six strategies are described and analyzed: (1) research and development, (2) an effort of consensus building among stakeholders known as the Whitehorse Mining Initiative, (3) international networking, (4) active involvement in the development of environmental management standards, (5) management reorganization and (6) voluntary agreements. The importance of external factors in the shaping of corporate environmental management practices is discussed, in particular the role of government. Progress has been achieved in three areas: (1) managerial practices and organization, (2) reducing the impacts of ongoing operations and (3) minimizing future liabilities, but two significant fields of conflict remain, namely mining in wilderness areas and projects on aboriginal lands.KEY WORDS: Canada; Environmental management; Minerals industry; Nonferrous metals; Sustainable development; Whitehorse Mining Initiative 相似文献
6.
牛桂敏 《城市环境与城市生态》2011,(4):43-46
以低碳经济理论为指导,分析了近年来天津产业结构调整成效和存在的不足,认为天津产业结构的“高碳锁定效应”仍较明显。按照发展低碳经济的要求,提出了天津产业结构调整战略:一是加强增量控制,产业增量向第三产业倾斜,逐步“减工业化”;工业增量向高新技术产业、战略性新兴产业倾斜,逐步“降重工业化”;严格限制新增高耗能产业项目,从源... 相似文献
7.
As uranium has practically no other industrial uses besides electricity generation, demand is determined by the requirements and stockpiling policies of electric utilities. The uranium market has experienced strong fluctuations and is currently affected by the reductions in nuclear forecasts resulting from the slowdown in electricity demand. Analysing supply/demand indicators proves, however, that in retrospect the development has been relatively smooth and it appears that oversupply is more a consequence of overly optimistic short-term expectations. In the future, especially in the long term, nuclear power policies continue to be concerned with striking a proper balance between increasing production capability and development of new reactor technologies which would be less dependent on the availability of uranium. A bounding scenario approach is applied in this article to the assessment of adequacy of supply under varying assumptions on the total installed nuclear capacity, available resource base and attainable production capability. 相似文献
8.
Aysin Sev 《Sustainable Development》2009,17(3):161-173
The importance of the construction industry for the three elements of sustainable development, namely economic growth, social progress and effective protection of the environment, cannot be disregarded. This paper aims to evolve a conceptual framework for implementing sustainability principles and strategies to the construction industry from a life‐cycle perspective to contribute to sustainable development. The framework relies on three basic principles, which are resource management, life‐cycle design and design for human and environment. Following a literature review, each principle involving strategies and methods to be applied during the life cycle of construction projects is explained and a few case studies are presented for clarity on the methods. The framework, offering tools for stakeholders of the construction industry, also aims to help to develop the most appropriate assessment tool, which is based on the priorities of critical conditions. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment. 相似文献
9.
Katerina Karamanoli Urania Menkissoglu-Spiroudi Artemios M. Bosabalidis Despina Vokou Helen-Isis A. Constantinidou 《Chemoecology》2005,15(2):59-67
Summary. The scope of this work was to examine whether leaf constitutive secondary metabolites play a role in determining bacterial colonization of the phyllosphere. To this aim, we surveyed nineteen native or cultivated plant species that share a common bacterial pool in a North Mediterranean area, and estimated the size of total and ice nucleation active (INA) bacterial populations on their leaves. Large differences in the colonization of their phyllosphere were found; the population size of epiphytic bacteria ranged from 7.5 × 102 to 1 × 106 CFU/g fresh weight, in eucalypt and celery, respectively. Species native in Mediterranean-type climate areas, particularly those belonging to the group of aromatic plants, are characterized by scarce presence of INA bacteria. The antibacterial activity of essential oils, surface phenolics and leaf tissue extracts was also estimated against the INA strains P. syringae and E. herbicola, isolated from two of these plant species. E. herbicola proved more sensitive than P. syringae. Of the species examined, oregano [Origanum vulgare L. subsp. hirtum (Link.) Ietswaart], an aromatic plant, had the highest antimicrobial activity, whereas six species showed no activity at all. Further experiments were performed with oregano and bean (Phaseolus vulgaris L.) that represent two extremes in their secondary metabolite content. Both plants were inoculated with P. syringae. By the end of incubation, the bacterial population on bean plants was about 100 times higher than that on oregano leaves. Scanning electron micrographs showed that bacterial growth on oregano leaves was confined to sites away from glandular hairs. Results from the bacterial colonization survey together with those from the toxicity tests showed that all species rich in antibacterial secondary metabolites harbored low leaf bacterial populations. These results provide substantial evidence that leaf secondary metabolites function as constitutive defense chemicals against microbial invasions. However, the fact that species with non- or moderately active leaf secondary metabolites are not always highly colonized suggests mediation of other unknown factors, the contribution of which requires further investigation. 相似文献
10.
《Environmetrics》2018,29(4)
Environmental health exposures to airborne chemicals often originate from chemical mixtures. Environmental health professionals may be interested in assessing exposure to one or more of the chemicals in these mixtures, but often, exposure measurement data are not available, either because measurements were not collected/assessed for all exposure scenarios of interest or because some of the measurements were below the analytical methods' limits of detection (i.e., censored). In some cases, based on chemical laws, two or more components may have linear relationships with one another, whether in single or multiple mixtures. Although bivariate analyses can be used if the correlation is high, correlations are often low. To serve this need, this paper develops a multivariate framework for assessing exposure using relationships of the chemicals present in these mixtures. This framework accounts for censored measurements in all chemicals, allowing us to develop unbiased exposure estimates. We assessed our model's performance against simpler models at a variety of censoring levels and assessed our model's 95% coverage. We applied our model to assess vapor exposure from measurements of three chemicals in crude oil taken on the Ocean Intervention III during the Deepwater Horizon oil spill response and cleanup. 相似文献