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671.
Bruce A. Ramsay Ilie Saracovan Juliana A. Ramsay Robert H. Marchessault 《Journal of Polymers and the Environment》1994,2(1):1-7
A simple method was developed for the preparation of an autoclavable, long-side-chain poly (-hydroxyalkanoate) (LSC-PHA) colloidal suspension, which was used as a substrate for enzymatic degradation and to prepare agar overlay plates for the isolation of microorganisms producing extracellular LSC-PHA depolymerase. Six cultures producing extracellular LSC-PHA depolymerase were isolated from a composted hydrocarbon-contaminated soil. All were pseudomonads or related bacteria. All (with the possible exception ofXanthomonas maltophilia) could produce LSC PHA. Except forX. maltophilia none could hydrolyze poly (-hydroxybutyrate). Screening of sevenPseudomonas strains known to accumulate LSC PHA showed that all were negative for extracellular LSC-PHA depolymerase production. It was concluded that extracellular LSC-PHA depolymerase producers are found mostly in the genusPseudomonas but that they are relatively uncommon. 相似文献
672.
We captured two species of deep-sea zoarcids, Melanostigma pammelas and Lycodapus mandibularis, from Monterey Bay California and maintained them in the laboratory. One shallow-water zoarcid, Eucryphycus californicus, and an ecologically and morphologically similar stichaeid fish Xiphister atropurpureus were collected from intertidal and subtidal habitats in Monterey Bay. We investigated the absorption and assimilation efficiencies
of these fishes to determine whether deep-sea species have evolved mechanisms to increase their efficiency of food use. Fishes
were placed in experimental chambers and fed a known quantity of food. Ammonia excretion was measured and feces were collected
daily. Both food and feces were analyzed for water, protein, lipid and ash to determine specific absorption efficiencies.
Absorption ranged from 87.7 to 92.4% and assimilation efficiencies from 84.0 to 86.5%. Meal sizes from 0.5 to 4.0% of body
weight did not affect the results. No significant differences were found between deep-sea and shallow-water species fed single
meals or fed ad libitum for 10 days. This suggests that the selective pressure to maximize absorption and assimilation is
universal and is not affected by the productivity of the habitat occupied. However, the relative size of the intestine in
the deep-sea species was significantly smaller suggesting that they had a lower metabolic cost to maintain their digestive
apparatus. It could not be concluded whether this was the result of pressure to conserve energy or rather the tendency of
the shallow-living species to ingest more refractory material (i.e. sediment, algae). 相似文献
673.
This paper describes the results of a survey of the North Sea and north Atlantic waters adjacent to the Orkney and Shetland Islands, from 23 May to 9 June, 1973, using simultaneous tows of the prototype Undulating Oceanographic Recorder (UOR) and the Continuous Plankton Recorder (CPR). The UOR sampled plankton and measured salinity and temperature over its undulation profile from 5 to 65 m in depth. The CPR sampled plankton at a fixed depth of 10 m. Three principal water masses were identified, each with a characteristic plankton community. 相似文献
674.
Lawrence D. Platt M.D. Greggory R. Devore Janet Horenstein Zdena Pavlova Bruce Kovacs Rena Ellen Falk 《黑龙江环境通报》1987,7(6):407-411
Fetal echocardiography was used to identify a cardiac rhabdomyoma in the second trimester. The combination of this finding with a maternal history of Tuberous Sclerosis allowed the patient and her family to make a more educated decision regarding termination of the pregnancy. Post mortem examination of the fetus confirmed the prenatal findings. This case report demonstrates the importance of ultrasound evaluation of the fetus at risk of recurrence of a genetic syndrome in which one or more anatomical defects might be seen. 相似文献
675.
Bruce H. Pugesek 《Behavioral ecology and sociobiology》1990,27(3):211-215
Summary Parental effort was studied among knownaged California gulls (Larus californicus) with a brood size of two. Results supported three of Triver's predictions from parent-offspring conflict theory. First, the amount of time parents withheld food from offspring increased with increasing offspring age. Second, older parents were less likely than younger parents to withhold food from offspring throughout the period of parental care. Third, older parents had a longer period of parental care compared to younger parents. Adult survival to future breeding seasons was inversely related to duration of parental care. Older parents, in association with their greater levels of parental effort, had a lower survival rate compared to that of younger parents. 相似文献
676.
In their analyses of the impact of pollution taxation on the location of polluting decisions, U. K. Mathur (J. Environ. Econom. Management 3, 16–28 (1976)) and S. S. Gokturk (J. Reg. Sci. 19, 461–467 (1979)) obtained the result that a tax increase on urban pollution concentration may not succeed in pushing the polluting firm away from the urban center. In this paper is shown that the sufficient condition for success in this case depends upon the specification of the production and pollution emissions technology and may be the opposite to the one posited by Mathur and has more intuitive appeal. 相似文献
677.
The effect of cadmium on antioxidant responses and the susceptibility to oxidative stress in the hydrothermal vent mussel Bathymodiolus azoricus 总被引:1,自引:0,他引:1
Rui Company Angela Serafim Richard Cosson Lionel Camus Bruce Shillito Aline Fiala-Médioni Maria João Bebianno 《Marine Biology》2006,148(4):817-825
Hydrothermal vents are a unique environment of extreme physical–chemical characteristics and biological species composition.
Cd is a toxic non-essential metal present in high concentrations in the hydrothermal vent environment, contrary to those found
in marine coastal areas. Cd toxicity has been related, among other things, with reactive oxygen species production, even though
this is a non-redox metal. Bathymodiolus azoricus is a deep-sea Mytilid bivalve very common in the Mid Atlantic Ridge (MAR) hydrothermal vent fields and very little is known
about the antioxidant defence system in this specie. Because lethal Cd concentration in B. azoricus is unknown, the aim of this study was to assess the effects of a Cd concentration higher than that found in the hydrothermal
vents on oxidative stress biomarkers, such as antioxidant enzymes. Mussels were exposed to 100 μg l−1 Cd during 24, 48 and 144 h, respectively, in a pressurized aquarium (IPOCAMP). Superoxide dismutase (SOD), catalase (CAT),
glutathione peroxidases (GPx), total oxyradical scavenging capacity (TOSC), metallothionein (MT) and lipid peroxidation (LPO)
were measured in the gills and mantle of B. azoricus. The results indicate that gills are first affected by Cd toxicity. This may be due to different physiological functions
of the tissues and by the presence of thio and methanotrophic symbiotic bacteria in the gills. The SOD and CAT are inhibited
during the first day of exposure in the gills, although TOSC and MT concentrations were the same in control and exposed mussels.
In the mantle, enzymatic activation only occurred after 6 days, and no significant differences in MT concentrations were found
in the control and exposed mussels during the first day, as observed in the gills. 相似文献
678.
Larry Larsen Terri Morrell David Wood Meghan Gallione Bruce Guerard Judith Karinen Kip Petersen Frederick Steiner 《Environmental management》1991,15(4):531-548
This is the second of three articles prepared to explain the Teller County growth management process. As part of an ongoing
growth management process in Teller County, Colorado, opportunities and constraints for development and conservation were
identified. The scenic mountain county faces a number of issues because of growth. The recognition of those issues has resulted
in the goal to direct future growth to the most appropriate and cost-effective places. To determine those places that are
best for new development, thorough ecological inventories were conducted for the entire county as well as for the City of
Woodland Park area. From these inventories, environmentally sensitive areas were identified. The environmentally sensitive
areas were considered constraints in conducting suitability analyses for a variety of potential land uses. The suitability
analyses resulted in the identification of opportunities for future growth in Teller County generally as well as the more
specific Woodland Park planning area. This article, like the other two, is part of a reflective analysis by the planners who
were involved.
Paper 2 in a series 3. 相似文献
679.
Marybeth Buechner Christine Schonewald-Cox Raymond Sauvajot Bruce A. Wilcox 《Environmental management》1992,16(6):799-809
In recent years, cross-boundary management has become an essential part of park management. In this article we compare the
perspectives of managers of several US national parks to the advice on this issue presented in the published literature. Data
were obtained from interviews of the superintendents, assistant superintendents and resources managers of five major western
national parks and from a survey of participants in a NPS workshop attended by park superintendents, scientists, and resource
managers; law enforcement personnel; and interpreters. Three themes related to boundary management were consistently stressed
by park managers: (10 a lack of sufficient funds and personnel within the parks; (2) the need for reliable information on
both political and natural processes; and, (3) the importance of personal interactions between park staff and individuals
from the surrounding area. Basic data collection, the documentation of trends, cooperative groups and personal contacts, educational
programs, and land acquisition were the most useful strategies. A lack of funds and information, ineffective communication,
enforcement problems, and a lack of motivation for parties to reach a negotiated agreement were the most serious obstacles.
A wide range of valuable institutional knowledge concerning boundary management exists within the National Park Service; however,
there appears to be a gap between published strategies and the approaches that work “on the ground”. 相似文献
680.
Socioeconomic, demographic, and attitudinal factors likely to influence individual initiative to use control measures against
gypsy moth infestation in New Hampshire are examined. Data were acquired through a mail survey from 629 individuals in three
targeted towns: Bow, Conway, and Exeter. Using logit regression analysis, numerous variables are shown to be statistically
significant in influencing an individual's willingness to use control measures. The influencing factors include: the individual
knowing the difference between the gypsy moth caterpillar and the eastern tent caterpillar; the individual being a homeowner
rather than a renter; the number of acres of land accompanying the individual's dwelling; the number of trees on the individual's
property; the individual's gender; and the individual's level of income. Aesthetic damage and the nuisance caused by gypsy
moth infestation were the primary reasons for individuals to use control measures. The results from this study indicate that
the motivation behind an individual's initiative to use control measures is influenced by diverse and varying factors. The
models, methodology, and results as applied and presented here are exploratory in nature, yet could prove informative for
researchers seeking a greater understanding of the interaction between humans and insect pests. 相似文献