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1

The effect of deleterious alleles on adaptation in asexual populations.  

PubMed Central

We calculate the fixation probability of a beneficial allele that arises as the result of a unique mutation in an asexual population that is subject to recurrent deleterious mutation at rate U. Our analysis is an extension of previous works, which make a biologically restrictive assumption that selection against deleterious alleles is stronger than that on the beneficial allele of interest. We show that when selection against deleterious alleles is weak, beneficial alleles that confer a selective advantage that is small relative to U have greatly reduced probabilities of fixation. We discuss the consequences of this effect for the distribution of effects of alleles fixed during adaptation. We show that a selective sweep will increase the fixation probabilities of other beneficial mutations arising during some short interval afterward. We use the calculated fixation probabilities to estimate the expected rate of fitness improvement in an asexual population when beneficial alleles arise continually at some low rate proportional to U. We estimate the rate of mutation that is optimal in the sense that it maximizes this rate of fitness improvement. Again, this analysis relaxes the assumption made previously that selection against deleterious alleles is stronger than on beneficial alleles.

Johnson, Toby; Barton, Nick H

2002-01-01

2

The effect of deleterious mutations on neutral molecular variation  

SciTech Connect

Selection against deleterious alleles maintained by mutation may cause a reduction in the amount of genetic variability at linked neutral sites. This is because a new neutral variant can remain in a large population for a long period of time only if it is maintained in gametes that are free of deleterious alleles, and hence are not destined for rapid elimination from the population by selection. Approximate formulas are derived for the reduction below classical neutral values resulting from such background selection against deleterious mutations, for the mean times of fixation and loss of new mutations, nucleotide site diversity, and number of segregating sites. These formulas apply to random-mating populations with no genetic recombination, and to populations reproducing exclusively asexually or by self-fertilization. For a given selection regime and mating system, the reduction is an exponential function of the total mutation rate to deleterious mutations for the section of the genome involved. Simulations show that the effect decreases rapidly with increasing recombination frequency or rate of outcrossing. The mean time to loss of new neutral mutations and the total number of segregating neutral sites are less sensitive to background selection than the other statistics, unless the population size is of the order of a hundred thousand or more. The stationary distribution of allele frequencies at the neutral sites is correspondingly skewed in favor of rare alleles, compared with the classical neutral result. Observed reductions in molecular variation in low recombination genomic regions of sufficiently large size, for instance in the centromere-proximal regions of Drosophila autosomes or in highly selfing plant populations, may be partly due to background selection against deleterious mutations. 58 refs., 3 figs., 6 tabs.

Charlesworth, B.; Morgan, M.T.; Charlesworth, D. (Univ. of Chicago, IL (United States))

1993-08-01

3

The Effects of Deleterious Mutations on Evolution at Linked Sites  

PubMed Central

The process of evolution at a given site in the genome can be influenced by the action of selection at other sites, especially when these are closely linked to it. Such selection reduces the effective population size experienced by the site in question (the Hill–Robertson effect), reducing the level of variability and the efficacy of selection. In particular, deleterious variants are continually being produced by mutation and then eliminated by selection at sites throughout the genome. The resulting reduction in variability at linked neutral or nearly neutral sites can be predicted from the theory of background selection, which assumes that deleterious mutations have such large effects that their behavior in the population is effectively deterministic. More weakly selected mutations can accumulate by Muller’s ratchet after a shutdown of recombination, as in an evolving Y chromosome. Many functionally significant sites are probably so weakly selected that Hill–Robertson interference undermines the effective strength of selection upon them, when recombination is rare or absent. This leads to large departures from deterministic equilibrium and smaller effects on linked neutral sites than under background selection or Muller’s ratchet. Evidence is discussed that is consistent with the action of these processes in shaping genome-wide patterns of variation and evolution.

Charlesworth, Brian

2012-01-01

4

Relative effectiveness of mating success and sperm competition at eliminating deleterious mutations in Drosophila melanogaster.  

PubMed

Condition-dependence theory predicts that sexual selection will facilitate adaptation by selecting against deleterious mutations that affect the expression of sexually selected traits indirectly via condition. Recent empirical studies have provided support for this prediction; however, their results do not elucidate the relative effects of pre- and postcopulatory sexual selection on deleterious mutations. We used the Drosophila melanogaster model system to discern the relative contributions of pre- and postcopulatory processes to selection against deleterious mutations. To assess second-male ejaculate competition success (P2; measured as the proportion of offspring attributable to the experimental male) and mating success, mutant and wild-type male D. melanogaster were given the opportunity to mate with females that were previously mated to a standard competitor male. This process was repeated for males subjected to a diet quality manipulation to test for effects of environmentally-manipulated condition on P2 and mating success. While none of the tested mutations affected P2, there was a clear effect of condition. Conversely, several of the mutations affected mating success, while condition showed no effect. Our results suggest that precopulatory selection may be more effective than postcopulatory selection at removing deleterious mutations. The opposite result obtained for our diet manipulation points to an interesting discrepancy between environmental and genetic manipulations of condition, which may be explained by the multidimensionality of condition. Establishing whether the various stages of sexual selection affect deleterious mutations differently, and to what extent, remains an important issue to resolve. PMID:22662148

Clark, Sean C A; Sharp, Nathaniel P; Rowe, Locke; Agrawal, Aneil F

2012-05-25

5

Genomic buffering mitigates the effects of deleterious mutations in bacteria  

Microsoft Academic Search

The relationship between the number of randomly accumulated mutations in a genome and fitness is a key parameter in evolutionary biology1-5. Mutations may interact such that their combined effect on fitness is additive (no epistasis), reinforced (synergistic epistasis) or mitigated (antagonistic epistasis). We measured the decrease in fitness caused by increasing mutation number in the bacterium Salmonella typhimurium using a

Sophie Maisnier-Patin; John R Roth; Åsa Fredriksson; Thomas Nyström; Otto G Berg; Dan I Andersson

2005-01-01

6

Sildenafil citrate attenuates the deleterious effects of elevated ammonia.  

PubMed

Ammonia is a bi-product of protein metabolism in the body. It is able to cross the blood-brain barrier and elevated ammonia levels are toxic to the brain. Rats with hyperammonemia showed impaired learning ability and impaired function of the glutamate-nitric oxide-cyclic guanosine monophosphate (glutamate-NO-cGMP) pathway in the brain. Chronic treatment with sildenafil restored learning ability. We therefore tested the hypothesis that sildenafil has a protective effect on the brains of hyperammonemic rats. Hyperammonemia was induced in male rats by daily intraperitoneal (i.p.) injection of ammonium chloride (100?mg/kg body weight) for 8 weeks. Sildenafil citrate was administered intraperitoneally (10?mg/kg body weight/3 days) for 8 weeks. Treatment with sildenafil resulted in a significant reduction in plasma liver enzymes, lipid profile as well as brain lipid peroxidation and caspase-3 mRNA. Meanwhile, plasma NO as well as cGMP, antioxidants and endothelial nitric oxide synthase (eNOS) gene expression were significantly elevated in the brains of hyperammonemic rats. Our results showed that sildenafil exerts a protective effect on the brain by reversing oxidative stress during hyperammonemia and this could be due to (i) cytoprotective, antioxidant and anti-apoptotic effects (ii) increasing cGMP and enhancing the proper metabolism of fats which could suppress oxygen radical generation and thus preventing oxidative damage in the brain. The exact protective mechanism of sildenafil has to be still investigated and further studies are warranted. Consequently, therapeutic modulation of the NO/cGMP pathway might have important clinical applications to improve brain functions in patients with hyperammonemia or clinical hepatic encephalopathy. PMID:23343352

Arafa, Manar H; Atteia, Hebatallah H

2013-03-27

7

Separating multiple, short-term deleterious effects of saline solutions to the growth of cowpea seedlings  

Technology Transfer Automated Retrieval System (TEKTRAN)

Reductions in plant growth due to salinity are of global importance in natural and agricultural landscapes. Short-term (48 h) solution culture experiments studied 404 treatments with seedlings of cowpea (Vigna unguiculata (L.) Walp. cv. Caloona) to examine the multiple deleterious effects of Ca, Mg...

8

DELETERIOUS RHIZOBACTERIA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Deleterious rhizobacteria (DRB) are predominantly saprophytic bacteria that aggressively colonize plant seeds, roots and rhizospheres and readily metabolize organic substances released by plant tissues. Unlike typical phytopathogens, DRB do not invade and parasitize vascular tissues; DRB that inhabi...

9

Deleterious Effects of Alcohol Intoxication: Diminished Cognitive Control and Its Behavioral Consequences  

Microsoft Academic Search

The authors tested the hypothesis that impaired behavioral performance during intoxication results partly from alcohol’s deleterious effects on cognitive control. The impact of alcohol on perseverative behavior was examined with an n-back working memory task that included manipulations of task complexity and prepotency of inclinations to respond or withhold responding. Thirty-two social drinkers (16 men) participated in either an alcohol

Todd S. Casbon; John J. Curtin; Alan R. Lang; Christopher J. Patrick

2003-01-01

10

Resveratrol inhibits the deleterious effects of diet-induced obesity on thymic function.  

PubMed

Obesity is associated with an increased risk of infectious diseases. It has been shown to have deleterious effects on cell-mediated immunity, including reducing thymocyte numbers and altering responses of thymocytes to pathogens. In the current study, we examined the efficacy of the antiobesity phytochemical resveratrol in preventing the deleterious effects of a high-fat diet on thymic anatomy and function. Compared to C57Bl/6 male mice fed a low-fat diet, mice on a high-fat diet had a significant increase in thymic weight and lipid content, and a disrupted anatomy, including a reduction of the medullary compartment and absence of a corticomedullary junction. There were a decrease in thymic cellularity and mature T-cell output, and a disrupted T-cell maturation, as evidenced by increased double-negative and decreased single- and double-positive thymocytes. Mice that had been fed resveratrol along with a high-fat diet had a dose-dependent reversal in all these parameters. Western blots from thymi showed that obese mice had lower levels of the key stimulators of lipid metabolism, phospho-5' adenosine monophosphate-activated protein kinase and its downstream target, carnitine palmitoyl transferase-1; this was restored to normal levels in resveratrol-fed mice. Resveratrol also reversed an increase in glycerol-3-phosphate acyltransferase-1, the enzyme that catalyzes the first step in triglycerol synthesis. Taken together, these results indicate that resveratrol is a potent inhibitor of the deleterious effects of diet-induced obesity on thymic anatomy and function, and this may hold promise in preventing obesity-related deficits in cell-mediated immunity. PMID:23561698

Gulvady, Apeksha A; Ciolino, Henry P; Cabrera, Robert M; Jolly, Christopher A

2013-04-03

11

Endocannabinoid system and nitric oxide are involved in the deleterious effects of lipopolysaccharide on murine decidua.  

PubMed

Endocannabinoids are an important family of lipid-signaling molecules that are widely distributed in mammalian tissues and anandamide (AEA) was the first member identified. The uterus contains the highest concentrations of AEA yet discovered in mammalian tissues and this suggests that it might play a role in reproduction. Previous results from our laboratory have shown that AEA modulated NO synthesis in rat placenta. The production of small amounts of nitric oxide regulates various physiological reproductive processes such as implantation, decidualization and myometrial relaxation. But in an inflammatory setting such as sepsis, NO is produced in big amounts and has toxic effects as it is a free radical. The results presented in this study indicate that LPS-induced NO synthesis and tissue damage were mediated by AEA. Decidual LPS-induced NO production was abrogated either by co-incubation with CB1 (AM251) or CB2 (SR144528) antagonists which suggests that both receptors could be mediating this effect. On the other hand, LPS-induced tissue damage and this deleterious effect was partially abrogated by incubating tissue explants with LPS plus CB1 receptor antagonist. Our findings suggest that AEA, probably by increasing NO synthesis, participates in the deleterious effect of LPS in implantation sites. These effects could be involved in pathological reproductive events such as septic abortion. PMID:19428101

Vercelli, C A; Aisemberg, J; Billi, S; Wolfson, M L; Franchi, A M

2009-05-09

12

Deleterious effect of CTLA4-Ig on a Treg-dependent transplant model.  

PubMed

Blockade of the B7:CD28 costimulatory pathway has emerged as a promising therapy to prevent allograft rejection. However, results from the belatacept phase III clinical trial demonstrated a higher rejection rate when compared to cyclosporine, raising concern about potential deleterious effects of this agent. In this study, we investigated the consequences of B7:CD28 blockade by hCTLA4Ig on regulator T cell (Treg) generation in different major histocompatibility complex (MHC) mismatch transplant models. Administration of hCTLA4Ig significantly decreased the amount of Tregs in B6 WT animals and this effect was predominant in thymus-induced Tregs (Helios(+) ). Although hCTLA4Ig prevented rejection in a fully allogeneic mismatch model, it accelerated rejection in a MHC class-II mismatch model (MST = 26, p < 0.0001), in which long-term allograft survival is dependent on Tregs. This accelerated rejection was associated with a marked reduction in thymus-induced Tregs and led to a higher effector/regulatory T-cell ratio in secondary lymphoid organs and in the allograft. This study confirms the importance of the B7:CD28 pathway in Treg homeostasis in an in vivo transplant model and suggests that hCTLA4Ig therapy may be deleterious in circumstances where engraftment is dependent on Tregs. PMID:22300534

Riella, L V; Liu, T; Yang, J; Chock, S; Shimizu, T; Mfarrej, B; Batal, I; Xiao, X; Sayegh, M H; Chandraker, A

2012-02-02

13

Deleterious effects of recombination and possible nonrecombinatorial advantages of sex in a fungal model.  

PubMed

Why sexual reproduction is so prevalent in nature remains a major question in evolutionary biology. Most of the proposed advantages of sex rely on the benefits obtained from recombination. However, it is still unclear whether the conditions under which these recombinatorial benefits would be sufficient to maintain sex in the short term are met in nature. Our study addresses a largely overlooked hypothesis, proposing that sex could be maintained in the short term by advantages due to functions linked with sex, but not related to recombination. These advantages would be so essential that sex could not be lost in the short term. Here, we used the fungus Aspergillus nidulans to experimentally test predictions of this hypothesis. Specifically, we were interested in (i) the short-term deleterious effects of recombination, (ii) possible nonrecombinatorial advantages of sex particularly through the elimination of mutations and (iii) the outcrossing rate under choice conditions in a haploid fungus able to reproduce by both outcrossing and haploid selfing. Our results were consistent with our hypotheses: we found that (i) recombination can be strongly deleterious in the short term, (ii) sexual reproduction between individuals derived from the same clonal lineage provided nonrecombinatorial advantages, likely through a selection arena mechanism, and (iii) under choice conditions, outcrossing occurs in a homothallic species, although at low rates. PMID:23848947

López-Villavicencio, M; Debets, A J M; Slakhorst, M; Giraud, T; Schoustra, S E

2013-07-13

14

Population Growth Inflates the Per-Individual Number of Deleterious Mutations and Reduces Their Mean Effect  

PubMed Central

This study addresses the question of how purifying selection operates during recent rapid population growth such as has been experienced by human populations. This is not a straightforward problem because the human population is not at equilibrium: population genetics predicts that, on the one hand, the efficacy of natural selection increases as population size increases, eliminating ever more weakly deleterious variants; on the other hand, a larger number of deleterious mutations will be introduced into the population and will be more likely to increase in their number of copies as the population grows. To understand how patterns of human genetic variation have been shaped by the interaction of natural selection and population growth, we examined the trajectories of mutations with varying selection coefficients, using computer simulations. We observed that while population growth dramatically increases the number of deleterious segregating sites in the population, it only mildly increases the number carried by each individual. Our simulations also show an increased efficacy of natural selection, reflected in a higher fraction of deleterious mutations eliminated at each generation and a more efficient elimination of the most deleterious ones. As a consequence, while each individual carries a larger number of deleterious alleles than expected in the absence of growth, the average selection coefficient of each segregating allele is less deleterious. Combined, our results suggest that the genetic risk of complex diseases in growing populations might be distributed across a larger number of more weakly deleterious rare variants.

Gazave, Elodie; Chang, Diana; Clark, Andrew G.; Keinan, Alon

2013-01-01

15

Doping dose of salbutamol and exercise: deleterious effect on cancellous and cortical bones in adult rats.  

PubMed

Animal studies suggest that bone remodeling is under beta-adrenergic control via the sympathetic nervous system. To our knowledge, the impact of beta-agonist substances, at doping doses, has not been studied in adult rats. The purpose of this study was to examine the effects of salbutamol injections with or without treadmill exercise on trabecular and cortical bone in adult rats. Adult (36 wk of age) female Wistar rats (n = 56) were treated with salbutamol (3 mg.kg(-1).day(-1) sc, 5 days/wk) or vehicle (sham) with or without subsequent treadmill exercise (13 m/min, 60 min/day, 5 days/wk) for 10 wk. Tibial and femoral bone mineral density was analyzed by dual-energy X-ray absorptiometry. Metaphysic trabecular bone structure was analyzed by micro-CT at the time of the animals' death. Bone cell activities were assessed histomorphometrically. After 10 wk, the increase in bone mineral density was less in salbutamol-treated than in sham rats (+3.3% vs. +12.4%, P < 0.05), and trabecular parameters were altered and bone resorption was increased in salbutamol-treated rats compared with controls. The negative effect on bone architecture in salbutamol-treated rats persisted, even with treadmill exercise. These results confirm the deleterious effect of beta(2)-agonists on bone mass during chronic treatment and describe its effects on bone mechanical properties in adult rats. Bone loss occurred independently of a salbutamol-induced anabolic effect on muscle mass and was equally severe in sedentary and exercising rats, despite a beneficial effect of exercise on the extrinsic and intrinsic energy to ultimate strain. These bone effects may have important consequences in athletes who use salbutamol as a doping substance. PMID:17185495

Bonnet, N; Benhamou, C L; Beaupied, H; Laroche, N; Vico, L; Dolleans, E; Courteix, D

2006-12-21

16

Lipotoxicity versus adipotoxicity—The deleterious effects of adipose tissue on beta cells in the pathogenesis of type 2 diabetes  

Microsoft Academic Search

Type 2 diabetes (T2D) is thought to be a culmination of two seemingly distinct processes, insulin resistance and beta cell failure, both of which have been closely linked to obesity. Here, we focus on the various deleterious effects of obesity on the beta cell. Obesity can affect beta cells directly through the influence of elevated levels of free fatty acids

Roy Eldor; Itamar Raz

2006-01-01

17

Is It Happening? How to Avoid the Deleterious Effects of Plagiarism and Cheating in Your Courses  

ERIC Educational Resources Information Center

Plagiarism can be "plaguing" if it is not discussed, understood, and enforced by the professor right at the beginning of the course and throughout the semester. Students usually don't "have" to cheat or plagiarize; they do so mainly because "they can." Professors who turn a deaf ear or a blind eye to students who plagiarize create deleterious

Hall, Susan E.

2011-01-01

18

Absence of deleterious effects of chronic microwave radiation on the eyes of rhesus monkeys  

Microsoft Academic Search

Microwave irradiation of rhesus monkeys' eyes at 9.31 and 2.45 GHz and at an average power density of 150 mW per centimeter square is reported. Irradiation, beginning in 1976, of 17 monkeys (Macaca mulatta) was accomplished without restraint or anesthesia by training the monkeys to irradiate themselves. To data microwave radiation of these monkeys has not resulted in deleterious ocular

R. D. McAfee; R. Ortiz-Lugo; R. Bishop; R. Gordon

1983-01-01

19

Vitamin E prevents deleterious effects of di (2-ethyl hexyl) phthalate, a plasticizer used in PVC blood storage bags.  

PubMed

Vitamin E administration prevented DEHP induced deleterious effects like (i) degenerative changes in the brain and thyroid, (ii) decrease in the activity of neuronal membrane Na+ - K+ ATPase, (iii) decrease in the concentration of insulin, cortisol and TSH, and (iv) the increase in T3 and T4 in female Albino rats. The results suggest use of vitamin E to prevent harmful effects of repeated transfusion of DEHP containing blood as in thalassemia patient. The possibility of using vitamin E to prevent the harmful effects of repeated transfusion of DEHP containing blood, as in thalassemia patients, is discussed. PMID:15462179

Dhanya, C R; Gayathri, N S; Mithra, K; Nair, K V Neelakantan; Kurup, P A

2004-09-01

20

Duration of Sexual Harassment and Generalized Harassment in the Workplace Over Ten Years: Effects on Deleterious Drinking Outcomes  

PubMed Central

While harassment in the workplace has been linked to deleterious drinking outcomes, researchers have yet to examine the long-term effects of chronic workplace harassment. During a ten year longitudinal mail survey, university employees (N = 2265) were administered measures of sexual harassment, generalized workplace harassment, and problematic drinking. Using growth mixture modeling, two latent classes of workplace harassment emerged: infrequent and chronic. Demographic characteristics (gender, age, and race) predicted the shape of the trajectories and likelihood of class membership. As hypothesized, membership in the chronic harassment classes was linked to future problematic drinking, even after controlling for previous drinking.

McGinley, Meredith; Richman, Judith A.; Rospenda, Kathleen M.

2012-01-01

21

Platelet-rich plasma protects rotator cuff-derived cells from the deleterious effects of triamcinolone acetonide.  

PubMed

Triamcinolone acetonide (TA) injections are widely used to treat enthesopathy, but they may induce adverse effects such as tendon impairment and rupture. Platelet-rich plasma (PRP) is a blood fraction containing high platelet concentrations and various growth factors that play a role in tissue repair processes. The purpose of this study is to investigate whether TA has deleterious effects on human rotator cuff-derived cells, and if PRP can protect these cells from the effects of TA. Human rotator cuff-derived cells were cultured with and without TA and PRP, and the culture without any additive served as the control. Cell morphology was assessed at days 7 and 21. Cell viability was evaluated at days 1, 7, 14, and 21 by a water-soluble tetrazolium salt assay. Induction of apoptosis was measured by immunofluorescence staining and flow cytometry at day 7. Induction of cleaved caspase-3 was measured by immunofluorescence staining at day 7. The cells cultured with TA had a flattened and polygonal shape at day 7. The cells cultured with both TA and PRP were similar in appearance to control cells. Exposure to TA also significantly decreased cell viability, but cell viability did not decrease when PRP was added along with TA. The number of apoptotic cells increased with TA exposure, while addition of PRP prevented cell apoptosis. In conclusion, the deleterious effect of TA was prevented by PRP, which can be used as a protective agent for patients receiving local TA injections. PMID:23280560

Muto, Tomoyuki; Kokubu, Takeshi; Mifune, Yutaka; Sakata, Ryosuke; Nagura, Issei; Nishimoto, Hanako; Harada, Yoshifumi; Nishida, Kotaro; Kuroda, Ryosuke; Kurosaka, Masahiro

2012-12-31

22

Oxidative stress is related to the deleterious effects of heme oxygenase-1 in an in vivo neuroinflammatory rat model.  

PubMed

Heme oxygenase-1 (HO-1) induction is associated with beneficial or deleterious effects depending on the experimental conditions adopted and the neurodegenerative rodent models used. The present study aimed first to evaluate the effects of cerebral HO-1 induction in an in vivo rat model of neuroinflammation by intrastriatal injection of quinolinic acid (QA) and secondly to explore the role played by reactive oxygen species (ROS) and free iron (Fe(2+)) derived from heme catabolism promoted by HO-1. Chronic I.P. treatment with the HO-1 inductor and substrate hemin was responsible for a significant dose-related increase of cerebral HO-1 production. Brain tissue loss, microglial activation, and neuronal death were significantly higher in rats receiving QA plus hemin (H-QA) versus QA and controls. Significant increase of ROS production in H-QA rat brain was inhibited by the specific HO-1 inhibitor ZnPP which supports the idea that ROS level augmentation in hemin-treated animals is a direct consequence of HO-1 induction. The cerebral tissue loss and ROS level in hemin-treated rats receiving the iron chelator deferoxamine were significantly decreased, demonstrating the involvement of Fe(2+)in brain ROS production. Therefore, the deleterious effects of HO-1 expression in this in vivo neuroinflammatory model were linked to a hyperproduction of ROS, itself promoted by free iron liberation. PMID:23533686

Tronel, Claire; Rochefort, Gaël Y; Arlicot, Nicolas; Bodard, Sylvie; Chalon, Sylvie; Antier, Daniel

2013-03-05

23

Ecological Effects of Climate Fluctuations  

Microsoft Academic Search

Climate influences a variety of ecological processes. These effects operate through local weather parameters such as temperature, wind, rain, snow, and ocean currents, as well as interactions among these. In the temperate zone, local variations in weather are often coupled over large geographic areas through the transient behavior of atmospheric planetary-scale waves. These variations drive temporally and spatially averaged exchanges

Nils Chr; Atle Mysterud; James W. Hurrell; Kung-Sik Chan

2002-01-01

24

Immunoperoxidase techniques: the deleterious effect of sodium azide on the activity of peroxidase conjugates  

Microsoft Academic Search

The effect of including sodium azide as a bacteriostatic agent in solutions used to dilute antibodies conjugated with the enzyme horseradish peroxidase was examined. An enzyme-linked immunosorbent assay (ELISA) and an immunohistochemical method were used and both techniques demonstrated an inhibitory effect of sodium azide on the activity of the peroxidase conjugates. It is concluded that the use of sodium

T C Richardson; D V Chapman; E Heyderman

1983-01-01

25

Skeletal site-specific effects of whole body vibration in mature rats: from deleterious to beneficial frequency-dependent effects.  

PubMed

Whole body vibration (WBV) is receiving increasing interest as an anti-osteoporotic prevention strategy. In this context, selective effects of different frequency and acceleration magnitude modalities on musculoskeletal responses need to be better defined. Our aim was to investigate the bone effects of different vibration frequencies at constant g level. Vertical WBV was delivered at 0.7 g (peak acceleration) and 8, 52 or 90 Hz sinusoidal vibration to mature male rats 10 min daily for 5 days/week for 4 weeks. Peak accelerations measured by skin or bone-mounted accelerometers at L2 vertebral and tibia crest levels revealed similar values between adjacent skin and bone sites. Local accelerations were greater at 8 Hz compared with 52 and 90 Hz and were greater in vertebra than tibia for all the frequencies tested. At 52 Hz, bone responses were mainly seen in L2 vertebral body and were characterized by trabecular reorganization and stimulated mineral apposition rate (MAR) without any bone volume alteration. At 90 Hz, axial and appendicular skeletons were affected as were the cortical and trabecular compartments. Cortical thickness increased in femur diaphysis (17%) along with decreased porosity; trabecular bone volume increased at distal femur metaphysis (23%) and even more at L2 vertebral body (32%), along with decreased SMI and increased trabecular connectivity. Trabecular thickness increased at the tibia proximal metaphysis. Bone cellular activities indicated a greater bone formation rate, which was more pronounced at vertebra (300%) than at long bone (33%). Active bone resorption surfaces were unaffected. At 8 Hz, however, hyperosteoidosis with reduced MAR along with increased resorption surfaces occurred in the tibia; hyperosteoidosis and trend towards decreased MAR was also seen in L2 vertebra. Trabecular bone mineral density was decreased at femur and tibia. Thus the most favorable regimen is 90 Hz, while deleterious effects were seen at 8 Hz. We concluded that the skeleton is frequency-scalable, thus highlighting the importance of WBV regimen conditions and suggesting that cautions are required for frequencies less than 10 Hz, at least in rats. PMID:23545229

Pasqualini, Marion; Lavet, Cédric; Elbadaoui, Mohamed; Vanden-Bossche, Arnaud; Laroche, Norbert; Gnyubkin, Vasily; Vico, Laurence

2013-03-29

26

The deleterious effect of ocular artefacts on the quantitative EEG, and a remedy  

Microsoft Academic Search

Summary The effect of ocular artefacts on spectral EEG parameters is assessed statistically. These artefacts are caused by movements of the eyeball and\\/or of the lid. Further, methods for correcting ocular artefacts are presented and evaluated. This methodological study is based on data from an investigation comparing the EEG of schizophrenic patients (n=17) with healthy controls (n=15). Ocular artefacts are

Theo Gasser; Peter Ziegler; Wagner F. Gattaz

1992-01-01

27

Exercise capacity after complete repair of tetralogy of Fallot: deleterious effects of residual pulmonary regurgitation  

Microsoft Academic Search

OBJECTIVE--To determine the effects of residual pulmonary regurgitation on exercise tolerance after complete repair of tetralogy of Fallot. DESIGN--Prospective study of symptom free patients more than five years after complete repair. Graded exercise performance was measured with standard Bruce protocol. Maximal oxygen uptake and ventilatory anaerobic threshold were measured by respiratory mass spectrometry. Measurement of pulmonary regurgitant fraction was from

J S Carvalho; E A Shinebourne; C Busst; M L Rigby; A N Redington

1992-01-01

28

Brief Report: Labelling Effects on the Perceived Deleterious Consequences of Pop Music Listening  

ERIC Educational Resources Information Center

|Several correlational studies have supported the claim of conservative protestors that there exists a positive relationship between listening to pop music and adolescent problem behaviours. However, research on the so-called 'prestige effects' has shown that experimental participants' responses to music can be mediated by manipulations of prior…

North, A.C.; Hargreaves, D.J.

2005-01-01

29

Deleterious effects of food restrictions in yellowtail kingfish Seriola lalandi during early development  

Microsoft Academic Search

The effects of delayed first feeding and food deprivation on the structure and function of the digestive system in yellowtail kingfish Seriola lalandi larvae and juveniles were studied through histological examinations and enzymatic analyses. The experimental design included a conventional feeding regime with initial feeding from 3 days after hatching (DAH) as a control, delayed first feeding until 5 DAH, a

Ben Nan Chen; Jian G. Qin; John F. Carragher; Steven M. Clarke; Martin S. Kumar; Wayne G. Hutchinson

2007-01-01

30

Hyperfractionation decreases the deleterious effects of conventional radiation fractionation on vertebral growth in animals  

SciTech Connect

Craniospinal axis irradiation in the treatment of pediatric tumors is associated with serious long-term sequelae including decreased bone growth (short sitting stature). In this study, an animal model was used to determine the effects of smaller incremental doses of radiation on bone growth. Sprague-Dawley weanling rats were given 25 Gy to the spine in 8 to 9 days, with fraction sizes ranging from 1.0 to 1.8 Gy. The animals receiving smaller doses per fraction (1.0 or 1.25 Gy) showed significantly more growth of the vertebral bodies in the treated fields than animals given larger incremental doses (1.5 or 1.8 Gy). These findings indicate a protective effect on bone growth for hyperfractionated irradiation of vertebral bodies.

Hartsell, W.F.; Hanson, W.R.; Conterato, D.J.; Hendrickson, F.R.

1989-06-15

31

Erythropoietin Promotes Deleterious Cardiovascular Effects and Mortality Risk in a Rat Model of Chronic Sports Doping  

Microsoft Academic Search

Athletes who abuse recombinant human erythropoietin (rhEPO) consider only the benefit to performance and usually ignore the\\u000a potential short and long-term liabilities. Elevated haematocrit and dehydratation associated with intense exercise may reveal\\u000a undetected cardiovascular risk, but the mechanisms underlying it remain to be fully explained. This study aimed to evaluate\\u000a the cardiovascular effects of rhEPO in rats under chronic aerobic

Nuno Piloto; Helena M. Teixeira; Edite Teixeira-Lemos; Belmiro Parada; Patrícia Garrido; José Sereno; Rui Pinto; Lina Carvalho; Elísio Costa; Luís Belo; Alice Santos-Silva; Frederico Teixeira; Flávio Reis

2009-01-01

32

Curcuma oil ameliorates hyperlipidaemia and associated deleterious effects in golden Syrian hamsters.  

PubMed

Essential oil components from turmeric (Curcuma longa L.) are documented for neuroprotective, anti-cancer, anti-thrombotic and antioxidant effects. The present study aimed to investigate the disease-modifying potential of curcuma oil (C. oil), a lipophilic component from C. longa L., in hyperlipidaemic hamsters. Male golden Syrian hamsters were fed a chow or high-cholesterol (HC) and fat-rich diet with or without C. oil (30, 100 and 300 mg/kg) for 28 d. In HC diet-fed hamsters, C. oil significantly reduced plasma total cholesterol, LDL-cholesterol and TAG, and increased HDL-cholesterol when compared with the HC group. Similar group comparisons showed that C. oil treatment reduced hepatic cholesterol and oxidative stress, and improved liver function. Hyperlipidaemia-induced platelet activation, vascular dysfunction and repressed eNOS mRNA expression were restored by the C. oil treatment. Furthermore, aortic cholesterol accumulation and CD68 expression were also reduced in the C. oil-treated group. The effect of C. oil at 300 mg/kg was comparable with the standard drug ezetimibe. Delving into the probable anti-hyperlipidaemic mechanism at the transcript level, the C. oil-treated groups fed the chow and HC diets were compared with the chow diet-fed group. The C. oil treatment significantly increased the hepatic expression of PPARa, LXRa, CYP7A1, ABCA1, ABCG5, ABCG8 and LPL accompanied by reduced SREBP-2 and HMGCR expression. C. oil also enhanced ABCA1, ABCG5 and ABCG8 expression and suppressed NPC1L1 expression in the jejunum. In the present study, C. oil demonstrated an anti-hyperlipidaemic effect and reduced lipid-induced oxidative stress, platelet activation and vascular dysfunction. The anti-hyperlipidaemic effect exhibited by C. oil seems to be mediated by the modulation of PPARa, LXRa and associated genes involved in lipid metabolism and transport. PMID:23673139

Singh, Vishal; Jain, Manish; Misra, Ankita; Khanna, Vivek; Rana, Minakshi; Prakash, Prem; Malasoni, Richa; Dwivedi, Anil Kumar; Dikshit, Madhu; Barthwal, Manoj Kumar

2013-05-15

33

Daunorubicin and doxorubicin but not BCNU have deleterious effects on organotypic multicellular spheroids of gliomas  

Microsoft Academic Search

In the present study organotypic multicellular spheroids (OMS) were used to study the effects of chemotherapeutic agents on malignant gliomas. Compared with the frequently used cell line models, OMS have several advantages with respect to the preservation of the cellular heterogeneity and the structure of the original tumour. OMS prepared from seven glioma specimens were treated with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), daunorubicin

P Kaaijk; D Troost; OJ de Boer; P Van Amstel; PJM Bakker; S Leenstra; DA Bosch

1996-01-01

34

Deleterious versus neuroprotective effect of metabolic inhibition after traumatic spinal cord injury  

Microsoft Academic Search

Study design:This work is an experimental and prospective study in adult, female, Long–Evans rats.Objectives:The aim of this study was to probe the effect of metabolic inhibition after an acute traumatic spinal cord injury (TSCI) using a standardized contusion model (NYU impactor) to know whether the metabolic inhibition is a ‘secondary mechanism of injury’ or a mechanism of protection.Setting:All experimental procedures

S Torres; H Salgado-Ceballos; G Guizar-Sahagún; J L Torres; S Orozco-Suarez; A Diaz-Ruiz; M E Vázquez; C Collado; C Ríos

2009-01-01

35

Deleterious effects of repeated cold exposure in a freeze-tolerant subAntarctic caterpillar  

Microsoft Academic Search

Multiple freeze-thaw cycles are common in alpine, polar and temperate habitats. We investigated the effects of five consecutive cycles of approx. -5°C on the freeze-tolerant larvae of Pringleophaga marioni Viette (Lepidoptera: Tineidae) on sub-Antarctic Marion Island. The likelihood of freezing was positively correlated with body mass, and decreased from 70% of caterpillars that froze on initial exposure to 55% of

Brent J. Sinclair; Steven L. Chown

2005-01-01

36

Deleterious effects of repeated cold exposure in a freeze-tolerant sub-Antarctic caterpillar.  

PubMed

Multiple freeze-thaw cycles are common in alpine, polar and temperate habitats. We investigated the effects of five consecutive cycles of approx. -5 degrees C on the freeze-tolerant larvae of Pringleophaga marioni Viette (Lepidoptera: Tineidae) on sub-Antarctic Marion Island. The likelihood of freezing was positively correlated with body mass, and decreased from 70% of caterpillars that froze on initial exposure to 55% of caterpillars that froze on subsequent exposures; however, caterpillars retained their freeze tolerance and did not appear to switch to a freeze-avoiding strategy. Apart from an increase in gut water, there was no difference in body composition of caterpillars frozen 0 to 5 times, suggesting that the observed effects were not due to freezing, but rather to exposure to cold per se. Repeated cold exposure did not result in mortality, but led to decreased mass, largely accounted for by a decreased gut mass caused by cessation of feeding by caterpillars. Treatment caterpillars had fragile guts with increased lipid content, suggesting damage to the gut epithelium. These effects persisted for 5 days after the final exposure to cold, and after 30 days, treatment caterpillars had regained their pre-exposure mass, whereas their control counterparts had significantly gained mass. We show that repeated cold exposure does occur in the field, and suggest that this may be responsible for the long life cycle in P. marioni. Although mean temperatures are increasing on Marion Island, several climate change scenarios predict an increase in exposures to sub-zero temperatures, which would result in an increased generation time for P. marioni. Coupled with increased predation from introduced house mice on Marion Island, this could have severe consequences for the P. marioni population. PMID:15755885

Sinclair, Brent J; Chown, Steven L

2005-03-01

37

Zinc therapy improves deleterious effects of chronic copper administration on mice testes: histopathological evaluation.  

PubMed

This study was set to investigate whether the adverse effects of long-term copper (Cu) consumption on testicular tissue could be prevented by zinc (Zn) administration. Forty-five mature male rats were randomly divided into one control and two treatment groups. The first treatment group received copper sulfate (Cu experimental group). The second treatment group was given combined treatment of copper sulfate and zinc sulfate (ZC experimental group). Control animals received normal saline using the same volume. Five rats from each group were sacrificed on day 14, 28 and 56 from the beginning of treatments. Left testes were removed for histopathological and histomorphometrical evaluations. Morphometrically, diameter of seminiferous tubules and sertoli cells nuclei, epithelial height, meiotic index and the percentage of spermatogenesis in Cu groups showed significant decrease than those of the control groups (P < 0.05). A partial improvement was seen about the percentage of spermatogenesis and meiotic index (P < 0.05) in ZC groups, whereas a complete recovery was observed in the rest of parameters in ZC group after 56 days compared to the control group (P > 0.05). Results showed that long-term administration of Cu leads to histological impairments of testis and zinc supplementation might offset these damaging effects. PMID:23137167

Kheirandish, R; Askari, N; Babaei, H

2012-11-01

38

l-Cysteine ethyl ester reverses the deleterious effects of morphine on, arterial blood-gas chemistry in tracheotomized rats.  

PubMed

This study determined whether the membrane-permeable ventilatory stimulant, l-cysteine ethylester (l-CYSee), reversed the deleterious actions of morphine on arterial blood-gas chemistry in isoflurane-anesthetized rats. Morphine (2mg/kg, i.v.) elicited sustained decreases in arterial blood pH, pO2 and sO2, and increases in pCO2 (all responses indicative of hypoventilation) and alveolar-arterial gradient (indicative of ventilation-perfusion mismatch). Injections of l-CYSee (100?mol/kg, i.v.) reversed the effects of morphine in tracheotomized rats but were minimally active in non-tracheotomized rats. l-cysteine or l-serine ethylester (100?mol/kg, i.v.) were without effect. It is evident that l-CYSee can reverse the negative effects of morphine on arterial blood-gas chemistry and alveolar-arterial gradient but that this positive activity is negated by increases in upper-airway resistance. Since l-cysteine and l-serine ethylester were ineffective, it is evident that cell penetrability and the sulfur moiety of l-CYSee are essential for activity. Due to its ready penetrability into the lungs, chest wall muscle and brain, the effects of l-CYSee on morphine-induced changes in arterial blood-gas chemistry are likely to involve both central and peripheral sites of action. PMID:23892097

Mendoza, James; Passafaro, Rachael; Baby, Santhosh; Young, Alex P; Bates, James N; Gaston, Benjamin; Lewis, Stephen J

2013-07-23

39

Domperidone can ameliorate deleterious reproductive effects and reduced weight gain associated with fescue toxicosis in heifers.  

PubMed

The aim of this study was to evaluate the effect of a dopamine antagonist, domperidone, in nonpregnant, reproductively cycling heifers consuming endophyte-infected (EI) fescue diets. Thirty crossbred heifers (Angus x Holstein or Hereford x Holstein) were assigned to one of three treatment groups (n = 10); endophyte-free (EF) fescue diet, EI fescue diet, or endophyte-infected diet and treated with domperidone (EID). Heifers fed EI diets had decreased weight gains compared with heifers fed EF or EID (P < 0.05) during a 21-d treatment period. Ovarian structures were monitored via transrectal ultrasound to determine follicle size and day of ovulation. Blood plasma samples were collected daily and analyzed for progesterone concentration to determine luteal function. Heifers ingesting EI diets had estrous cycles of shorter duration and lower mid-cycle progesterone concentrations than heifers in the EF or EID treatments (P < 0.05). Ovaries from a subset of heifers in each group (n = 3 per group) were harvested and in vitro secretion of progesterone from luteal tissue extracts was determined. No differences in progesterone concentrations were detected among luteal tissue incubates (P > 0.05). These results suggest that domperidone supplementation of heifers consuming EI fescue may ameliorate certain symptoms of fescue toxicosis. PMID:14552385

Jones, K L; King, S S; Griswold, K E; Cazac, D; Cross, D L

2003-10-01

40

Using ergosterol to mitigate the deleterious effects of ethanol on bilayer structure.  

PubMed

In wine fermentations, yeast is exposed to concentrated ethanol solutions. Ergosterol, a sterol that is found in lower eukaryotic membranes, helps preserve the structural integrity of yeast membranes in stressful environmental conditions. A premature arrest in ethanol production due to unknown metabolic changes in yeasts results in undesirably large concentrations of residual sugar and may be caused by the formation of an ethanol-induced interdigitated phase. We use atomistic molecular dynamics simulations to examine the induction of the interdigitated phase in model yeast membranes that contain either 0, 10, 20, 25 mol % ergosterol in ethanol concentrations of 0, 10, 15 vol %. The 25 mol % ergosterol system shows a similar level of interdigitation for the 0 and 10 vol % ethanol solutions, indicating that ergosterol molecules in this system are able to effectively counteract the disruptive behavior of ethanol molecules. However, at a 15 vol % ethanol solution, the amount of interdigitation triples and this ethanol concentration is similar to the concentrations found in stuck fermentations. The other three ergosterol concentrations studied (0, 10, 20 mol %) show larger quantities of interdigitation in the 10 vol % ethanol solution than the 0 vol % solution. Thus, the 25 mol % ergosterol bilayer, which is representative of the ergosterol concentrations seen in yeast membranes, is unique in the systems examined in its ability to delay the onset of ethanol-induced interdigitation. The concentration of ergosterol affects the permeability of a fluid-phase bilayer, where the 10 mol % ergosterol bilayer is more permeable to ethanol than either a bilayer containing no ergosterol molecules or a bilayer containing 20/25 mol % ergosterol. This lipid permeability appears to be correlated with the existence of a lipid region whose lipids neither have direct contact with ergosterol molecules nor exhibit bulk lipid/lipid interactions. PMID:19191714

Dickey, Allison N; Yim, Wen-Sau; Yim, Wen-Saul; Faller, Roland

2009-02-26

41

Deleterious effects of white cells in the course of skin damage in CVI.  

PubMed

Venous ulceration remains a common problem and a significant challenge to the physicians treating it. Many theories have been advanced in the past to explain its causes but there is little evidence to support tissue hypoxia as the main factor, as was once thought. In recent years attention has focussed on the inflammatory events which attend venous disease and the development of venous ulceration. It has been proposed that these form a major contribution to the development of venous leg ulcers. In the arterial system an analogous series of events appears to cause damage following severe ischemia. Massive neutrophil activation in the microcirculation following reperfusion of a tissue results in severe, ischemic damage to that tissue. A similar series of events is proposed to explain venous disease. During venous hypertension leukocytes are sequestrated in the microcirculation of the lower limb. It has been shown that these undergo activation whilst they are in the leg. The exact location of leukocyte sequestration is unclear but it is suggested that this may occur in the skin. The damage caused to the lower limb skin components can be identified by measuring plasma levels of endothelial adhesion molecules, which are shed into the circulation following a period of venous hypertension. In the long term this leads to a chronic inflammatory state in the skin in some patients where venous hypertension is sustained or there is susceptibility to venous hypertension. The resulting inflammatory process is referred to as "lipodermatosclerosis" and has a number of well known clinical features. There is proliferation of the dermal capillaries eventually leading to a "glomerulus" like appearance. In the skin and subcutaneous tissues there is fibrosis. The microcirculation in the papillary dermis is surrounded by an inflammatory cellular infiltrate. The importance of understanding the mechanisms of the development of venous ulceration is in creating new treatments for this problem. Compression treatment has been effective in healing leg ulcers for thousands of years. Surgical treatment offers a possible cure in patients where superficial venous reflux is the main problem. Deep vein reconstruction is only suitable for a few patients. Many venous ulcers can be healed by compression, only to recur within a few months. Pharmacological treatments may offer the possibility of more rapid ulcer healing and the maintenance of an ulcer-free state if the correct pathophysiological mechanisms can be identified and addressed. PMID:12515977

Coleridge Smith, P D

2002-06-01

42

Reversing the deleterious effects of aging on neuronal communication and behavior: beneficial properties of fruit polyphenolic compounds.  

PubMed

Despite elegant research involving molecular biology studies and determination of the genetic mechanisms of aging, practical information on how to forestall or reverse the deleterious effects of aging may be years away. If this is the case, then it is prudent to try to establish other methods that can be used now to alter the course of aging. Numerous epidemiologic studies have indicated that individuals who consume diets containing large amounts of fruits and vegetables may reduce their risk for developing age-related diseases such as Alzheimer disease. Research from our laboratory suggested that dietary supplementation with fruit or vegetable extracts high in antioxidants (eg, blueberry or spinach extracts) might decrease the enhanced vulnerability to oxidative stress that occurs in aging. These reductions might be expressed as improvements in motor and cognitive behavior. Additional research suggested that mechanisms in addition to antioxidant and antiinflammatory activities might be involved in the beneficial effects of these extracts; the most important of these might be their ability to increase cellular signaling and neuronal communication. PMID:15640496

Joseph, James A; Shukitt-Hale, Barbara; Casadesus, Gemma

2005-01-01

43

Overexpression of Human and Fly Frataxins in Drosophila Provokes Deleterious Effects at Biochemical, Physiological and Developmental Levels  

PubMed Central

Background Friedreich's ataxia (FA), the most frequent form of inherited ataxias in the Caucasian population, is caused by a reduced expression of frataxin, a highly conserved protein. Model organisms have contributed greatly in the efforts to decipher the function of frataxin; however, the precise function of this protein remains elusive. Overexpression studies are a useful approach to investigate the mechanistic actions of frataxin; however, the existing literature reports contradictory results. To further investigate the effect of frataxin overexpression, we analyzed the consequences of overexpressing human (FXN) and fly (FH) frataxins in Drosophila. Methodology/Principal Findings We obtained transgenic flies that overexpressed human or fly frataxins in a general pattern and in different tissues using the UAS-GAL4 system. For both frataxins, we observed deleterious effects at the biochemical, histological and behavioral levels. Oxidative stress is a relevant factor in the frataxin overexpression phenotypes. Systemic frataxin overexpression reduces Drosophila viability and impairs the normal embryonic development of muscle and the peripheral nervous system. A reduction in the level of aconitase activity and a decrease in the level of NDUF3 were also observed in the transgenic flies that overexpressed frataxin. Frataxin overexpression in the nervous system reduces life span, impairs locomotor ability and causes brain degeneration. Frataxin aggregation and a misfolding of this protein have been shown not to be the mechanism that is responsible for the phenotypes that have been observed. Nevertheless, the expression of human frataxin rescues the aconitase activity in the fh knockdown mutant. Conclusion/Significance Our results provide in vivo evidence of a functional equivalence for human and fly frataxins and indicate that the control of frataxin expression is important for treatments that aim to increase frataxin levels.

Soriano, Sirena; Botella, Jose A.; Schneuwly, Stephan; Martinez-Sebastian, Maria J.; Molto, Maria D.

2011-01-01

44

Deleterious effects of water-soluble fraction of petroleum, diesel and gasoline on marine pejerrey Odontesthes argentinensis larvae.  

PubMed

Accidental discharges and oil spills are frequent around the world. Petroleum-derived hydrocarbons are considered one of the main pollutants of aquatic ecosystem. The importance of petroleum and refined fuels is notorious because today's society depends on them. Researches related to the toxic water-soluble fraction (WSF) of petroleum and derivatives to aquatic biota are scarce. For this reason, deleterious effects of WSF of Brazilian petroleum, automotive diesel and unleaded gasoline to marine pejerrey Odontesthes argentinensis larvae were studied employing toxicity tests and histopathological examination. Each WSF was generated in a laboratory by mixing four parts of seawater with one part of pollutant by approximately 22 h. Larvae were exposed during 96 h to different concentrations of WSF of petroleum, diesel, and gasoline, plus a control. After 96 h of exposure to the different WSFs, three larvae were sampled for histopathological studies. The median lethal concentration after 96 h (LC50) of exposure for WSF of petroleum was equal to 70.68%, it was significantly higher (P<0.05) than the values for WSF of diesel and gasoline, which were 13.46% and 5.48%, respectively. The histological examination of pejerrey larvae exposed to WSF of petroleum, diesel and gasoline after 96 h revealed a variety of lesions in the larvae. The gills, pseudobranchs and esophagus presented epithelial hyperplasia, and the liver presented dilatation of hepatic sinusoids, hepatocitomegaly, bi-nucleated and nuclear degeneration of hepatocytes, such as pyknotic nuclei. The acute toxicity of diesel and gasoline is at least fivefold higher than Brazilian petroleum. However, all toxicants induced histopathological abnormalities in pejerrey larvae. The results are of importance since much attention has been paid to large visible surfaces of petroleum spills instead of potential toxic effects of dissolved aromatic hydrocarbons, which are more available to marine biota. PMID:20167351

Rodrigues, Ricardo Vieira; Miranda-Filho, Kleber Campos; Gusmão, Emeline Pereira; Moreira, Cauê Bonucci; Romano, Luis Alberto; Sampaio, Luís André

2010-02-18

45

The presence of Bacillus thuringiensis (Bt) protein in earthworms Eisenia fetida has no deleterious effects on their growth and reproduction.  

PubMed

Earthworms Eisenia fetida, bred in substances with stover of two genetically-engineered Bacillus thuringiensis (Bt) corns (5422Bt1 (Event Bt11) and 5422CBCL (MON810)) expressing Cry1Ab and their near-isogenic non-Bt corn (5422), were used to investigate the non-target effects of Bt corn on soil-dwelling organisms. Cry1Ab concentrations in substances, casts and guts of E. fetida were also investigated by Enzyme-linked immunosorbent assay (ELISA). More than 90% individuals of E. fetida survived over a period of 30 d, irrespective of whether they received Bt corn or non-Bt corn. Compared to 5422 treatments, significantly higher relative growth rate and more number of new offspring and cocoons of E. fetida were found in 5422Bt1 and 5422CBCL treatments. These results were unlikely to be directly caused by Cry1Ab released from Bt corns but rather by differences in other factors of plants such as plant components (soluble sugar, total organic carbon, total protein and available phosphorus of Bt corns were more than 5422). ELISA results indicated immunoreactive Cry1Ab was detectable in substances, and the casts, guts of E. fetida from Bt corns treatments, of which the highest levels were detected in substances under the corresponding experimental conditions. With the increase of treated time, a strong decline was observed in Cry1Ab from substances and casts of E. fetida, whereas Cry1Ab in guts of E. fetida from 5422Bt1 treatments gradually increased and that from 5422CBCL treatments increased between 14 and 30 d. Therefore, the presence of Cry1Ab in E. fetida had no deleterious effects on their growth and reproduction. PMID:21955355

Shu, Yinghua; Ma, Honghui; Du, Yan; Li, Zhixian; Feng, Yuanjiao; Wang, Jianwu

2011-09-28

46

Deleterious effects of an environmental noise on sleep and contribution of its physical components in a rat model  

Microsoft Academic Search

Sleep disturbances induced by environmental noise (EN) exposure are now well admitted. However, many contradictory conclusions and discrepancies have been reported, resulting from uncontrolled human factors or the use of artificial noises (pure tone). Thus, the development of an animal model appears to be a useful strategy for determining whether EN is deleterious to sleep. The aims of this study

J. J Bouyer; J. M Aran; A Courtiere; W Mayo; M Le Moal

2004-01-01

47

Deleterious effects in mice of fish-associated methylmercury contained in a diet mimicking the Western populations' average fish consumption.  

PubMed

Methylmercury (MeHg) is a potent neurotoxin, and human beings are mainly exposed to this pollutant through fish consumption. Only a few contradictory epidemiological studies are currently available examining the impact of fish consumption on human populations. In the present study, we wanted to address whether a diet mimicking the fish consumption of Western populations could result in observable adverse effects in mice, and whether beneficial nutriments from fish were able to counterbalance the deleterious effects of MeHg, if any. In Europe and the United States, fish consumption varies widely between countries, from 11 to 100 g fish/day. A mid-range value of 25 g fish/day corresponds to a fish contribution to the total diet of 1.25% on a dry weight basis. We decided to supplement a vegetarian-based mouse diet with 1.25% of lyophilized salmon flesh (SAL diet), or 1.25% of a blend of lyophilized cod, tuna, and swordfish (CTS diet). Total mercury contents were 1.15±0.15, 2.3±0.1 and 35.75±0.15 ng Hg/g of food pellets for the control, SAL and CTS diets, respectively. After two months feeding, the CTS diet resulted in significant observable effects as compared to the control and SAL diets, encompassing decreased body growth, altered behavioral performance and increased anxiety level, modification of mitochondrial respiratory protein subunit concentrations in kidney and brain structures, modified gene expression patterns in kidneys, liver and muscles, and a decrease of dopamine concentrations in the hypothalamus and striatum. Our findings have health implications, firstly because 1.25% of CTS flesh in the diet corresponds to an average exposure to MeHg below the WHO provisory tolerable weekly intake (PTWI) (1.6 ?g MeHg/kg of body weight/week), and secondly because many people in Western populations, among them women of child-bearing age, are exceeding the PTWI value (for instance, 35% of the French population inhabiting the Atlantic and Mediterranean coasts). PMID:21035857

Bourdineaud, Jean-Paul; Fujimura, Masatake; Laclau, Muriel; Sawada, Masumi; Yasutake, Akira

2010-10-30

48

Deleterious Effects of Freezing on Osteogenic Differentiation of Human Adipose-Derived Stromal Cells In Vitro and In Vivo  

PubMed Central

Human adipose-derived stromal cells (hASCs) represent a multipotent stromal cell type with a proven capacity to undergo osteogenic differentiation. Many hurdles exist, however, between current knowledge of hASC osteogenesis and their potential future use in skeletal tissue regeneration. The impact of frozen storage on hASC osteogenic differentiation, for example, has not been studied in detail. To examine the effects of frozen storage, hASCs were harvested from lipoaspirate and either maintained in standard culture conditions or frozen for 2 weeks under standard conditions (90% fetal bovine serum, 10% dimethyl sulfoxide). Next, in vitro parameters of cell morphology (surface electron microscopy [EM]), cell viability and growth (trypan blue; bromodeoxyuridine incorporation), osteogenic differentiation (alkaline phosphatase, alizarin red, and quantitative real-time (RT)–polymerase chain reaction), and adipogenic differentiation (Oil red O staining and quantitative RT–polymerase chain reaction) were performed. Finally, in vivo bone formation was assessed using a critical-sized cranial defect in athymic mice, utilizing a hydroxyapatite (HA)-poly(lactic-co-glycolic acid) scaffold for ASC delivery. Healing was assessed by serial microcomputed tomography scans and histology. Freshly derived ASCs differed significantly from freeze–thaw ASCs in all markers examined. Surface EM showed distinct differences in cellular morphology. Proliferation, and osteogenic and adipogenic differentiation were all significantly hampered by the freeze–thaw process in vitro (*P?deleterious effects of the freeze–thaw process.

James, Aaron W.; Levi, Benjamin; Nelson, Emily R.; Peng, Michelle; Commons, George W.; Lee, Min; Wu, Benjamin

2011-01-01

49

Deleterious effects of freezing on osteogenic differentiation of human adipose-derived stromal cells in vitro and in vivo.  

PubMed

Human adipose-derived stromal cells (hASCs) represent a multipotent stromal cell type with a proven capacity to undergo osteogenic differentiation. Many hurdles exist, however, between current knowledge of hASC osteogenesis and their potential future use in skeletal tissue regeneration. The impact of frozen storage on hASC osteogenic differentiation, for example, has not been studied in detail. To examine the effects of frozen storage, hASCs were harvested from lipoaspirate and either maintained in standard culture conditions or frozen for 2 weeks under standard conditions (90% fetal bovine serum, 10% dimethyl sulfoxide). Next, in vitro parameters of cell morphology (surface electron microscopy [EM]), cell viability and growth (trypan blue; bromodeoxyuridine incorporation), osteogenic differentiation (alkaline phosphatase, alizarin red, and quantitative real-time (RT)-polymerase chain reaction), and adipogenic differentiation (Oil red O staining and quantitative RT-polymerase chain reaction) were performed. Finally, in vivo bone formation was assessed using a critical-sized cranial defect in athymic mice, utilizing a hydroxyapatite (HA)-poly(lactic-co-glycolic acid) scaffold for ASC delivery. Healing was assessed by serial microcomputed tomography scans and histology. Freshly derived ASCs differed significantly from freeze-thaw ASCs in all markers examined. Surface EM showed distinct differences in cellular morphology. Proliferation, and osteogenic and adipogenic differentiation were all significantly hampered by the freeze-thaw process in vitro (*P?deleterious effects of the freeze-thaw process. PMID:20536327

James, Aaron W; Levi, Benjamin; Nelson, Emily R; Peng, Michelle; Commons, George W; Lee, Min; Wu, Benjamin; Longaker, Michael T

2010-10-17

50

Ecological effects in multi-level studies  

PubMed Central

Multi-level research that attempts to describe ecological effects in themselves (for example, the effect on individual health from living in deprived communities), while also including individual level effects (for example, the effect of personal socioeconomic disadvantage), is now prominent in research on the socioeconomic determinants of health and disease. Such research often involves the application of advanced statistical multi-level methods. It is hypothesised that such research is at risk of reaching beyond an epidemiological understanding of what constitutes an ecological effect, and what sources of error may be influencing any observed ecological effect. This paper aims to present such an epidemiological understanding. Three basic types of ecological effect are described: a direct cross level effect (for example, living in a deprived community directly affects individual personal health), cross level effect modification (for example, living in a deprived community modifies the effect of individual socioeconomic status on individual health), and an indirect cross level effect (for example, living in a deprived community increases the risk of smoking, which in turn affects individual health). Sources of error and weaknesses in study design that may affect estimates of ecological effects include: a lack of variation in the ecological exposure (and health outcome) in the available data; not allowing for intraclass correlation; selection bias; confounding at both the ecological and individual level; misclassification of variables; misclassification of units of analysis and assignment of individuals to those units; model mis-specification; and multicollinearity. Identification of ecological effects requires the minimisation of these sources of error, and a study design that captures sufficient variation in the ecological exposure of interest.???Keywords: multi-level methods; ecological research design; socioeconomic factors; confounding; bias; effect modifiers; causality

Blakely, T.; Woodward, A.

2000-01-01

51

School Effectiveness in Ecological Perspective.  

ERIC Educational Resources Information Center

This report focuses on the learning and development of primary and secondary school children, employing an "ecology of human development" model. This model is defined as involving the scientific study of the accommodation between growing human beings and the changing immediate settings in which they live and learn. The conceptual framework for the…

Bronfenbrenner, Urie; Hamilton, Stephen F.

52

ROADS AND THEIR MAJOR ECOLOGICAL EFFECTS  

Microsoft Academic Search

A huge road network with vehicles ramifies across the land, representing a sur- prising frontier of ecology. Species-rich roadsides are conduits for few species. Roadkills are a premier mortality source, yet except for local spots, rates rarely limit population size. Road avoidance, especially due to traffic noise, has a greater ecological impact. The still-more-important barrier effect subdivides populations, with demographic

Richard T. T. Forman; Lauren E. Alexander

1998-01-01

53

Ecological effects in multi-level studies  

Microsoft Academic Search

Multi-level research that attempts to describe ecological effects in themselves (for example, the effect on individual health from living in deprived communities), while also including individual level effects (for example, the effect of personal socioeconomic disadvantage), is now prominent in research on the socioeconomic determinants of health and disease. Such research often involves the application of advanced statistical multi-level methods.

Tony A Blakely; Alistair J Woodward

2000-01-01

54

Testing the ability of non-methylamine osmolytes present in kidney cells to counteract the deleterious effects of urea on structure, stability and function of proteins.  

PubMed

Human kidney cells are under constant urea stress due to its urine concentrating mechanism. It is believed that the deleterious effect of urea is counteracted by methylamine osmolytes (glycine betaine and glycerophosphocholine) present in kidney cells. A question arises: Do the stabilizing osmolytes, non-methylamines (myo-inositol, sorbitol and taurine) present in the kidney cells also counteract the deleterious effects of urea? To answer this question, we have measured structure, thermodynamic stability (?G D (o)) and functional activity parameters (K m and k cat) of different model proteins in the presence of various concentrations of urea and each non-methylamine osmolyte alone and in combination. We observed that (i) for each protein myo-inositol provides perfect counteraction at 1?2 ([myo-inositol]:[urea]) ratio, (ii) any concentration of sorbitol fails to refold urea denatured proteins if it is six times less than that of urea, and (iii) taurine regulates perfect counteraction in a protein specific manner; 1.5?2.0, 1.2?2.0 and 1.0?2.0 ([taurine]:[urea]) ratios for RNase-A, lysozyme and ?-lactalbumin, respectively. PMID:24039776

Khan, Sheeza; Bano, Zehra; Singh, Laishram R; Hassan, Md Imtaiyaz; Islam, Asimul; Ahmad, Faizan

2013-09-09

55

Ecological Correlates of Effective Foster Care  

ERIC Educational Resources Information Center

Providing effective foster care is a major undertaking that continues to plague this country. The ultimate goal of substitute care is to provide child victims of maltreatment with a safe and nurturing home environment. The goal of this theory driven research project was to identify ecological factors correlated with effective non-kin family foster…

Henderson, Daphne; Scannapieco, Maria

2006-01-01

56

Measuring spontaneous deleterious mutation process  

Microsoft Academic Search

Parameters of the deleterious mutation process can be estimated using the data on genotypes, phenotypes, or fitnesses. These\\u000a data can be on long-term evolution, on short-term changes, or on the properties of equilibrium populations. The two most important\\u000a parameters at the genomic level, the total deleterious mutation rate U and the mutational pressure on fitness P, remain poorly\\u000a known. Reliable

Alexey S. Kondrashov

1998-01-01

57

Deleterious effects of sugar and protective effects of starch on cardiac remodeling, contractile dysfunction, and mortality in response to pressure overload.  

PubMed

Little is known about the effects of the composition of dietary carbohydrate on the development of left ventricular (LV) hypertrophy (LVH) and heart failure (HF) under conditions of pressure overload. The objective of this study was to determine the effect of carbohydrate composition on LVH, LV function, and mortality in a mouse model of chronic pressure overload. Male C57BL/6J mice of 6 wk of age (n = 14-16 mice/group) underwent transverse aortic constriction (TAC) or sham surgery and were fed either standard chow (STD; 32% corn starch, 35% sucrose, 3% maltodextrin, and 10% fat expressed as a percent of the total energy), high-starch chow (58% corn starch, 12% maltodextrin, and 10% fat), or high-fructose chow (9% corn starch, 61% fructose, and 10% fat). After 16 wk of treatment, mice with TAC fed the STD or high-fructose diets exhibited increased LV mass, larger end-diastolic and end-systolic diameters, and decreased ejection fraction compared with sham. The high-starch diet, in contrast, prevented changes in LV dimensions and contractile function. Cardiac mRNA for myosin heavy chain-beta was increased dramatically in the fructose-fed banded animals, as was mortality (54% compared with 8% and 29% in the starch and STD banded groups, respectively). In conclusion, a diet high in simple sugar was deleterious, resulting in the highest mortality and expression of molecular markers of cardiac dysfunction in TAC animals compared with sham, whereas a high-starch diet blunted mortality, increases in cardiac mass, and contractile dysfunction. PMID:17616744

Chess, David J; Lei, Biao; Hoit, Brian D; Azimzadeh, Agnes M; Stanley, William C

2007-07-06

58

An assessment of the ecological effects of acidic deposition  

Microsoft Academic Search

Research on the ecological effects of acidic deposition has yielded information that currently permits a partial assessment of these effects. Establishing a relationship between deposition of acidity and ecological effects is a difficult, lengthy process; the complexity of ecosystems requires an integrated mechanism-level approach in order to obtain quantitative and predictive information. Known ecological effects of acidic deposition appear in

John W. Huckabee; Jack S. Mattice; Louis F. Pitelka; Donald B. Porcella; Robert A. Goldstein

1989-01-01

59

APPLICATION OF 1- METHYLCYCLOPROPENE REVERSES THE DELETERIOUS EFFECT OF EXOGENOUS ETHYLENE ON FRESH-CUT WATERMELON AND CONTROLS MICROBIAL GROWTH  

Technology Transfer Automated Retrieval System (TEKTRAN)

The effects of exogenous ethylene, 1- methylcyclopropene (1-MCP), or both on microbial growth on watermelon fruit and watermelon slices were investigated. Freshly harvested seedless watermelons (Citrullus lanatus Thunb. Matsum and Nakai, variety Sugar Heart) were treated with 0, 0.5 or 1 ppm 1- MCP,...

60

ECOLOGICAL EFFECTS OF GENE FLOW.  

EPA Science Inventory

The Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) and the Government Performance Results Act (GPRA, goal number four for Safe Communities), constitute the statutory authority and strategic framework respectively, for Agency research on non-target effects of pestici...

61

Overcoming the deleterious effect of hafnium in tungsten–zirconia catalysts: The use of doping and thermal treatments  

Microsoft Academic Search

The effect of hafnium and aluminum addition to Ni\\/WO3\\/ZrO2 was examined as a function of calcination temperature for the isomerization of a 5 wt% cyclohexane in n-hexane feed. Hafnium, a common and difficult to separate impurity in zirconia, was found to decrease catalytic activity, primarily through the generation of monoclinic and cubic phases that are considered inactive for acid-catalyzed reactions.

David Simon; Bradley Taylor

2009-01-01

62

Age Shall Not Weary Us: Deleterious Effects of Self-Regulation Depletion Are Specific to Younger Adults  

PubMed Central

Self-regulation depletion (SRD), or ego-depletion, refers to decrements in self-regulation performance immediately following a different self-regulation-demanding activity. There are now over a hundred studies reporting SRD across a broad range of tasks and conditions. However, most studies have used young student samples. Because prefrontal brain regions thought to subserve self-regulation do not fully mature until 25 years of age, it is possible that SRD effects are confined to younger populations and are attenuated or disappear in older samples. We investigated this using the Stroop color task as an SRD induction and an autobiographical memory task as the outcome measure. We found that younger participants (<25 years) were susceptible to depletion effects, but found no support for such effects in an older group (40–65 years). This suggests that the widely-reported phenomenon of SRD has important developmental boundary conditions casting doubt on claims that it represents a general feature of human cognition.

Dahm, Theresa; Neshat-Doost, Hamid Taher; Golden, Ann-Marie; Horn, Elizabeth; Hagger, Martin; Dalgleish, Tim

2011-01-01

63

Cannabidiol provides long-lasting protection against the deleterious effects of inflammation in a viral model of multiple sclerosis: A role for A2A receptors.  

PubMed

Inflammation in the central nervous system (CNS) is a complex process that involves a multitude of molecules and effectors, and it requires the transmigration of blood leukocytes across the blood-brain barrier (BBB) and the activation of resident immune cells. Cannabidiol (CBD), a non-psychotropic cannabinoid constituent of Cannabis sativa, has potent anti-inflammatory and immunosuppressive properties. Yet, how this compound modifies the deleterious effects of inflammation in TMEV-induced demyelinating disease (TMEV-IDD) remains unknown. Using this viral model of multiple sclerosis (MS), we demonstrate that CBD decreases the transmigration of blood leukocytes by downregulating the expression of vascular cell adhesion molecule-1 (VCAM-1), chemokines (CCL2 and CCL5) and the proinflammatory cytokine IL-1?, as well as by attenuating the activation of microglia. Moreover, CBD administration at the time of viral infection exerts long-lasting effects, ameliorating motor deficits in the chronic phase of the disease in conjunction with reduced microglial activation and pro-inflammatory cytokine production. Adenosine A2A receptors participate in some of the anti-inflammatory effects of CBD, as the A2A antagonist ZM241385 partially blocks the protective effects of CBD in the initial stages of inflammation. Together, our findings highlight the anti-inflammatory effects of CBD in this viral model of MS and demonstrate the significant therapeutic potential of this compound for the treatment of pathologies with an inflammatory component. PMID:23851307

Mecha, M; Feliú, A; Iñigo, P M; Mestre, L; Carrillo-Salinas, F J; Guaza, C

2013-07-11

64

Antioxidant supplementation overcomes the deleterious effects of maternal restraint stress-induced oxidative stress on mouse oocytes.  

PubMed

In this study, using a mouse model, we tested the hypothesis that restraint stress would impair the developmental potential of oocytes by causing oxidative stress and that antioxidant supplementation could overcome the adverse effect of stress-induced oxidative stress. Female mice were subjected to restraint stress for 24?h starting 24?h after equine chorionic gonadotropin injection. At the end of stress exposure, mice were either killed to recover oocytes for in vitro maturation (IVM) or injected with human chorionic gonadotropin and caged with male mice to observe in vivo development. The effect of antioxidants was tested in vitro by adding them to IVM medium or in vivo by maternal injection immediately before restraint stress exposure. Assays carried out to determine total oxidant and antioxidant status, oxidative stress index, and reactive oxygen species (ROS) and glutathione levels indicated that restraint stress increased oxidative stress in mouse serum, ovaries, and oocytes. Whereas the percentage of blastocysts and number of cells per blastocyst decreased significantly in oocytes from restraint-stressed mice, addition of antioxidants to IVM medium significantly improved their blastocyst development. Supplementation of cystine and cysteamine to IVM medium reduced ROS levels and aneuploidy while increasing glutathione synthesis and improving pre- and postimplantation development of oocytes from restraint-stressed mice. Furthermore, injection of the antioxidant epigallocatechin gallate into restraint-stressed mice significantly improved the blastocyst formation and postimplantation development of their oocytes. In conclusion, restraint stress at the oocyte prematuration stage impaired the developmental potential of oocytes by increasing oxidative stress and addition of antioxidants to IVM medium or maternal antioxidant injection overcame the detrimental effect of stress-induced oxidative stress. The data reported herein are helpful when making attempts to increase the chances of a successful outcome in human IVF, because restraint was applied at a stage similar to the FSH stimulation period in a human IVF program. PMID:24043846

Lian, Hua-Yu; Gao, Yan; Jiao, Guang-Zhong; Sun, Ming-Ju; Wu, Xiu-Fen; Wang, Tian-Yang; Li, Hong; Tan, Jing-He

2013-10-21

65

Ecology of estuaries: Anthropogenic effects  

Microsoft Academic Search

Estuaries and near-shore oceanic water are subjected to a multitude of human wastes. The principal objective of this book is to examine anthropogenic effects on estuaries, and it focuses primarily on contaminants in coastal systems. Covered within various chapters are the following topics: waste disposal strategies; definition and classification of pollutants (including organic loading, oil pollution, polynuclear aromatic hydrocarbons; chlorinated

Kennish; Michael J. Kennish

1992-01-01

66

Deleterious effect of suboptimal diet on rest-activity cycle in Anastrepha ludens manifests itself with age.  

PubMed

Activity patterns and sleep-wake cycles are among the physiological processes that change most prominently as animals age, and are often good indicators of healthspan. In this study, we used the video-based high-resolution behavioral monitoring system (BMS) to monitor the daily activity cycle of tephritid fruit flies Anastrepha ludens over their lifetime. Surprisingly, there was no dramatic change in activity profile with respect to age if flies were consistently fed with a nutritionally balanced diet. However, if flies were fed with sugar-only diet, their activity profile decreased in amplitude at old age, suggesting that suboptimal diet affected activity patterns, and its detrimental effect may not manifest itself until the animal ages. Moreover, by simulating different modes of behavior monitoring with a range of resolution and comparing the resulting conclusions, we confirmed the superior performance of video-based monitoring using high-resolution BMS in accurately representing activity patterns in an insect model. PMID:23639915

Chiu, Joanna C; Kaub, Kevin; Zou, Sige; Liedo, Pablo; Altamirano-Robles, Leopoldo; Ingram, Donald; Carey, James R

2013-01-01

67

You have the right to understand: the deleterious effect of stress on suspects' ability to comprehend Miranda.  

PubMed

Miranda v. Arizona (384 U.S. 436, 1966) required that suspects be explicitly warned of the right to avoid self-incrimination and the right to legal representation. This research was designed to examine whether stress, induced via an accusation of wrong-doing, undermined or enhanced suspects' ability to comprehend their Miranda rights. Participants were randomly assigned to either be accused (n = 15) or not accused (n = 15) of having cheated on an experimental task in a two-cell between-subjects experimental design. Results supported the hypothesis that stress undermines suspects' ability to comprehend their Miranda rights. Participants who were accused of cheating exhibited significantly lower levels of Miranda comprehension than participants who were not accused of cheating. The theoretical processes responsible for these effects and the implications of the findings for police interrogation are discussed. PMID:22849413

Scherr, Kyle C; Madon, Stephanie

2012-08-01

68

A novel U-STAT3-dependent mechanism mediates the deleterious effects of chronic nicotine exposure on renal injury  

PubMed Central

Previous data from our group have demonstrated (Arany I, Grifoni S, Clark JS, Csongradi, Maric C, Juncos LA. Am J Physiol Renal Physiol 301: F125–F133, 2011) that chronic nicotine (NIC) exposure exacerbates acute renal ischemic injury (AKI) in mice that could increase the risk for development and progression of chronic kidney disease (CKD). It has been shown that proximal tubules of the kidney can acquire characteristics that may compromise structural recovery and favor development of inflammation and fibrosis following injury. Chronic NIC exposure can amplify this epithelial process although the mechanism is not identified. Recently, the unphosphorylated form of signal transducer and activator of transcription-3 (U-STAT3) has emerged as a noncanonical mediator of inflammation and fibrosis that may be responsible for the effects of chronic NIC. We found that levels of transforming growth factor ?-1 (TGF-?1), ?-smooth muscle actin (?-SMA), fibronectin, monocyte chemotactic protein-1 (MCP-1), and expression of U-STAT3 were increased in the ischemic kidneys of NIC-exposed mice. Chronic NIC exposure also increased TGF-?1-dependent F-actin reorganization, vimentin, fibronectin, and ?-SMA expression as well as promoter activity of ?-SMA and MCP-1 without significant loss of epithelial characteristics (E-cadherin) in cultured renal proximal tubule cells. Importantly, transduction of cells with a U-STAT3 mimetic (Y705F-STAT3) augmented stress fiber formation and also amplified NIC+TGF-?1-induced expression of ?-SMA, vimentin, fibronectin, as well as promoter activity of ?-SMA and MCP-1. Our results reveal a novel, chronic NIC-exposure-related and U-STAT3-dependent mechanism as mediator of a sustained transcription of genes that are linked to remodeling and inflammation in the kidney during injury. This process may facilitate progression of AKI to CKD. The obtained data may lead to devising therapeutic methods to specifically enhance the protective and/or inhibit adverse effects of STAT3 in the kidney.

Reed, Dustin K.; Grifoni, Samira C.; Chandrashekar, Kiran; Booz, George W.; Juncos, Luis A.

2012-01-01

69

In utero exposure to low doses of bisphenol A lead to long-term deleterious effects in the vagina.  

PubMed

The origins of the "endocrine disrupter hypothesis" may be traced to reports on adolescent daughters born to women who had taken the highly potent synthetic estrogen, diethylstilbestrol, while pregnant, and who developed a rare form of vaginal cancer and adenocarcinoma. Bisphenol A (BPA) is an estrogenic chemical that is highly employed in the manufacture of a wide range of consumer products. Some observational studies have suggested that the amounts of BPA to which we are exposed could alter the reproductive organs of developing rodents. We examined the influence of BPA at low doses to address the questions of (a) whether in utero exposure affects the vagina of the offspring and (b) which mechanisms cause the toxic effects. Gravid Sprague-Dawley dams were administered either 0.1 (low dose) or 50 mg/kg per day BPA, the no observed effect level, or 0.2 mg/kg per day 17 alpha-ethinyl estradiol by gavage. Striking morphological changes were observed in the vagina of postpubertal offspring leading us to examine vaginal estrogen receptor (ER) expression because BPA binds to the ER alpha, which is important for growth of the vaginal epithelium. We show that the full-length ER alpha is not expressed during estrus in the vagina of female offspring exposed to either dose of BPA when compared to the control group, whereas ER alpha expression does not differ from the control group during the diestrus stage. ER alpha downregulation seems to be responsible for the observed altered vaginal morphology. PMID:11896564

Schönfelder, G; Flick, B; Mayr, E; Talsness, C; Paul, M; Chahoud, I

70

A biophysical approach to menadione membrane interactions: relevance for menadione-induced mitochondria dysfunction and related deleterious/therapeutic effects.  

PubMed

Menadione (MEN), a polycyclic aromatic ketone, was shown to promote cell injury by imposing massive oxidative stress and has been proposed as a promising chemotherapeutic agent for the treatment of cancer diseases. The mechanisms underlying MEN-induced mitochondrial dysfunction and cell death are not yet fully understood. In this work, a systematic study was performed to unveil the effects of MEN on membrane lipid organization, using models mimicking mitochondrial membranes and native mitochondrial membranes. MEN was found to readily incorporate in membrane systems composed of a single phospholipid (phosphatidylcholine) or the lipids dioleoylphosphatidylcholine, dioleoylphosphatidylethanolamine and tetraoleoylcardiolipin at 1:1:1 molar ratio, as well as in mitochondrial membranes. Increased permeability in both membrane models, monitored by calcein release, seemed to correlate with the extent of MEN incorporation into membranes. MEN perturbed the physical properties of vesicles composed of dipalmitoylphosphatidylcholine or dipalmitoylphosphatidylethanolamine plus tetraoleoylcardiolipin (at 7:3 molar ratio), as reflected by the downshift of the lipid phase transition temperature and the emergence of a new transition peak in the mixed lipid system, detected by DSC. (31)P NMR studies revealed that MEN favored the formation of non-lamellar structures. Also, quenching studies with the fluorescent probes DPH and TMA-DPH showed that MEN distributed across the bilayer thickness in both model and native mitochondrial membranes. MEN's ability to promote alterations of membrane lipid organization was related with its reported mitochondrial toxicity and promotion of apoptosis, predictably involved in its anti-carcinogenic activity. PMID:23590997

Monteiro, João P; Martins, André F; Nunes, Cláudia; Morais, Catarina M; Lúcio, Marlene; Reis, Salette; Pinheiro, Teresa J T; Geraldes, Carlos F G C; Oliveira, Paulo J; Jurado, Amália S

2013-04-13

71

Extrapolating the effect of deleterious nsSNPs in the binding adaptability of flavopiridol with CDK7 protein: a molecular dynamics approach  

PubMed Central

Background Recent reports suggest the role of nonsynonymous single nucleotide polymorphisms (nsSNPs) in cyclin-dependent kinase 7 (CDK7) gene associated with defect in the DNA repair mechanism that may contribute to cancer risk. Among the various inhibitors developed so far, flavopiridol proved to be a potential antitumor drug in the phase-III clinical trial for chronic lymphocytic leukemia. Here, we described a theoretical assessment for the discovery of new drugs or drug targets in CDK7 protein owing to the changes caused by deleterious nsSNPs. Methods Three nsSNPs (I63R, H135R, and T285M) were predicted to have functional impact on protein function by SIFT, PolyPhen2, I-Mutant3, PANTHER, SNPs&GO, PhD-SNP, and screening for non-acceptable polymorphisms (SNAP). Furthermore, we analyzed the native and proposed mutant models in atomic level 10 ns simulation using the molecular dynamics (MD) approach. Finally, with the aid of Autodock 4.0 and PatchDock, we analyzed the binding efficacy of flavopiridol with CDK7 protein with respect to the deleterious mutations. Results By comparing the results of all seven prediction tools, three nsSNPs (I63R, H135R, and T285M) were predicted to have functional impact on the protein function. The results of protein stability analysis inferred that I63R and H135R exhibited less deviation in root mean square deviation in comparison with the native and T285M protein. The flexibility of all the three mutant models of CDK7 protein is diverse in comparison with the native protein. Following to that, docking study revealed the change in the active site residues and decrease in the binding affinity of flavopiridol with mutant proteins. Conclusion This theoretical approach is entirely based on computational methods, which has the ability to identify the disease-related SNPs in complex disorders by contrasting their costs and capabilities with those of the experimental methods. The identification of disease related SNPs by computational methods has the potential to create personalized tools for the diagnosis, prognosis, and treatment of diseases. Lay abstract Cell cycle regulatory protein, CDK7, is linked with DNA repair mechanism which can contribute to cancer risk. The main aim of this study is to extrapolate the relationship between the nsSNPs and their effects in drug-binding capability. In this work, we propose a new methodology which (1) efficiently identified the deleterious nsSNPs that tend to have functional effect on protein function upon mutation by computational tools, (2) analyze d the native protein and proposed mutant models in atomic level using MD approach, and (3) investigated the protein-ligand interactions to analyze the binding ability by docking analysis. This theoretical approach is entirely based on computational methods, which has the ability to identify the disease-related SNPs in complex disorders by contrasting their costs and capabilities with those of the experimental methods. Overall, this approach has the potential to create personalized tools for the diagnosis, prognosis, and treatment of diseases.

2013-01-01

72

Ecological Engineering Practices for the Reduction of Excess Nitrogen in Human-Influenced Landscapes: A Guide for Watershed Managers  

EPA Science Inventory

Excess nitrogen (N) in freshwater systems, estuaries, and coastal areas has well-documented deleterious effects on ecosystems. Ecological engineering practices (EEPs) may be effective at decreasing nonpoint source N leaching to surface and groundwater. However, few studies have s...

73

Ecologic versus individual-level sources of bias in ecologic estimates of contextual health effects.  

PubMed

A number of authors have attempted to defend ecologic (aggregate) studies by claiming that the goal of those studies is estimation of ecologic (contextual or group-level) effects rather than individual-level effects. Critics of these attempts point out that ecologic effect estimates are inevitably used as estimates of individual effects, despite disclaimers. A more subtle problem is that ecologic variation in the distribution of individual effects can bias ecologic estimates of contextual effects. The conditions leading to this bias are plausible and perhaps even common in studies of ecosocial factors and health outcomes because social context is not randomized across typical analysis units (administrative regions). By definition, ecologic data contain only marginal observations on the joint distribution of individually defined confounders and outcomes, and so identify neither contextual nor individual-level effects. While ecologic studies can still be useful given appropriate caveats, their problems are better addressed by multilevel study designs, which obtain and use individual as well as group-level data. Nonetheless, such studies often share certain special problems with ecologic studies, including problems due to inappropriate aggregation and problems due to temporal changes in covariate distributions. PMID:11821344

Greenland, S

2001-12-01

74

Deleterious background selection with recombination  

SciTech Connect

An analytic expression for the expected nucleotide diversity is obtained for a neutral locus in a region with deleterious mutation and recombination. Our analytic results are used to predict levels of variation for the entire third chromosome of Drosophila melanogaster. The predictions are consistent with the low levels of variation that have been observed at loci near the centromeres of the third chromosome of D. melanogaster. However, the low levels of variation observed near the tips of this chromosome are not predicted using currently available estimates of the deleterious mutation rate and of selection coefficients. If considerably smaller selection coefficients are assumed, the low observed levels of variation at the tips of the third chromosome are consistent with the background selection model. 33 refs., 4 figs., 1 tab.

Hudson, R.R. [Univ. of California, Irvine, CA (United States); Kaplan, N.L. [National Institute of Environmental Health Sciences, Research Triangle Park, NC (United States)

1995-12-01

75

Spontaneous deleterious mutation in Arabidopsis thaliana  

PubMed Central

The frequency and selective impact of deleterious mutations are fundamental parameters in evolutionary theory, yet they have not been directly measured in a plant species. To estimate these quantities, we allowed spontaneous mutations to accumulate for 10 generations in 1,000 inbred lines of the annual, self-fertilizing plant Arabidopsis thaliana and assayed fitness differences between generations 0 and 10 in a common garden. Germination rate, fruit set, and number of seeds per fruit each declined by less than 1% per generation in the mutation lines, and total fitness declined by 0.9% per generation. Among-line variances increased in the mutation lines for all traits. Application of an equal-effects model suggests a downwardly biased genomic deleterious mutation rate of 0.1 and a upwardly biased effect of individual mutations on total fitness of 20%. This genomic deleterious mutation rate is consistent with estimates of nucleotide substitution rates in flowering plants, the genome size of Arabidopsis, and the equilibrium inbreeding depression observed in this highly selfing plant species.

Schultz, Stewart T.; Lynch, Michael; Willis, John H.

1999-01-01

76

Properties and modeling of GWAS when complex disease risk is due to non-complementing, deleterious mutations in genes of large effect.  

PubMed

Current genome-wide association studies (GWAS) have high power to detect intermediate frequency SNPs making modest contributions to complex disease, but they are underpowered to detect rare alleles of large effect (RALE). This has led to speculation that the bulk of variation for most complex diseases is due to RALE. One concern with existing models of RALE is that they do not make explicit assumptions about the evolution of a phenotype and its molecular basis. Rather, much of the existing literature relies on arbitrary mapping of phenotypes onto genotypes obtained either from standard population-genetic simulation tools or from non-genetic models. We introduce a novel simulation of a 100-kilobase gene region, based on the standard definition of a gene, in which mutations are unconditionally deleterious, are continuously arising, have partially recessive and non-complementing effects on phenotype (analogous to what is widely observed for most Mendelian disorders), and are interspersed with neutral markers that can be genotyped. Genes evolving according to this model exhibit a characteristic GWAS signature consisting of an excess of marginally significant markers. Existing tests for an excess burden of rare alleles in cases have low power while a simple new statistic has high power to identify disease genes evolving under our model. The structure of linkage disequilibrium between causative mutations and significantly associated markers under our model differs fundamentally from that seen when rare causative markers are assumed to be neutral. Rather than tagging single haplotypes bearing a large number of rare causative alleles, we find that significant SNPs in a GWAS tend to tag single causative mutations of small effect relative to other mutations in the same gene. Our results emphasize the importance of evaluating the power to detect associations under models that are genetically and evolutionarily motivated. PMID:23437004

Thornton, Kevin R; Foran, Andrew J; Long, Anthony D

2013-02-21

77

The Abundance of Deleterious Polymorphisms in Humans  

PubMed Central

Here I show a gradual decline in the proportion of deleterious nonsynonymous SNPs (nSNPs) from tip to root of the human population tree. This study reveals that up to 48% of nSNPs specific to a single genome are deleterious in nature, which underscores the abundance of deleterious polymorphisms in humans.

Subramanian, Sankar

2012-01-01

78

Potential Ecological Effects of Contaminants in the Exposed Par Pond Sediments  

SciTech Connect

Sediment and small mammal samples were collected from the exposed sediments of Par Pond in early 1995, shortly before the reservoir was refilled after a 4-year drawdown. Sampling was confined to elevations between 58 and 61 meters (190 and 200 feet) above mean sea level, which includes the sediments likely to be exposed if the Par Pond water level is permitted to fluctuate naturally. Both soil and small mammal samples were analyzed for a number of radionuclides and metals. Some of the soil samples were also analyzed for organic contaminants. The objective of the study was to determine if contaminant levels in the Par Pond sediments were high enough to cause deleterious ecological effects.

Paller, M.H. [Westinghouse Savannah River Company, AIKEN, SC (United States); Wike, L.D.

1996-08-01

79

The chemical ecology of Harmonia axyridis  

Technology Transfer Automated Retrieval System (TEKTRAN)

We review the chemical ecology of the ladybird beetle Harmonia axyridis from the perspective of its invasiveness and the deleterious effects it exerts in the regions it has colonised. We outline the nature and quantification of its chemical defence, and discuss the protection this provides from natu...

80

Palytoxin and Analogs: Biological and Ecological Effects  

PubMed Central

Palytoxin (PTX) is a potent marine toxin that was originally found in soft corals from tropical areas of the Pacific Ocean. Soon after, its occurrence was observed in numerous other marine organisms from the same ecological region. More recently, several analogs of PTX were discovered, remarkably all from species of the dinoflagellate genus Ostreopsis. Since these dinoflagellates are also found in other tropical and even in temperate regions, the formerly unsuspected broad distribution of these toxins was revealed. Toxicological studies with these compounds shows repeatedly low LD50 values in different mammals, revealing an acute toxic effect on several organs, as demonstrated by different routes of exposure. Bioassays tested for some marine invertebrates and evidences from environmental populations exposed to the toxins also give indications of the high impact that these compounds may have on natural food webs. The recognition of its wide distribution coupled with the poisoning effects that these toxins can have on animals and especially on humans have concerned the scientific community. In this paper, we review the current knowledge on the effects of PTX and its analogs on different organisms, exposing the impact that these toxins may have in coastal ecosystems.

Ramos, Vitor; Vasconcelos, Vitor

2010-01-01

81

Effective discharge analysis of ecological processes in streams  

USGS Publications Warehouse

[1] Discharge is a master variable that controls many processes in stream ecosystems. However, there is uncertainty of which discharges are most important for driving particular ecological processes and thus how flow regime may influence entire stream ecosystems. Here the analytical method of effective discharge from fluvial geomorphology is used to analyze the interaction between frequency and magnitude of discharge events that drive organic matter transport, algal growth, nutrient retention, macroinvertebrate disturbance, and habitat availability. We quantify the ecological effective discharge using a synthesis of previously published studies and modeling from a range of study sites. An analytical expression is then developed for a particular case of ecological effective discharge and is used to explore how effective discharge varies within variable hydrologic regimes. Our results suggest that a range of discharges is important for different ecological processes in an individual stream. Discharges are not equally important; instead, effective discharge values exist that correspond to near modal flows and moderate floods for the variable sets examined. We suggest four types of ecological response to discharge variability: discharge as a transport mechanism, regulator of habitat, process modulator, and disturbance. Effective discharge analysis will perform well when there is a unique, essentially instantaneous relationship between discharge and an ecological process and poorly when effects of discharge are delayed or confounded by legacy effects. Despite some limitations the conceptual and analytical utility of the effective discharge analysis allows exploring general questions about how hydrologic variability influences various ecological processes in streams. Copyright 2005 by the American Geophysical Union.

Doyle, M. W.; Stanley, E. H.; Strayer, D. L.; Jacobson, R. B.; Schmidt, J. C.

2005-01-01

82

Ecology.  

ERIC Educational Resources Information Center

|This set of teaching aids consists of nine Audubon Nature Bulletins, providing teachers and students with informational reading on various ecological topics. The bulletins have these titles: Schoolyard Laboratories, Owls and Predators, The Forest Community, Life in Freshwater Marshes, Camouflage in the Animal World, Life in the Desert, The…

National Audubon Society, New York, NY.

83

Ecological Effects of the War in Vietnam  

ERIC Educational Resources Information Center

|Research report on the severe ecological consequences of the defoliation program by American military forces in Vietnam. A significant fraction of mature trees in most forests are killed by single application of herbicides and almost completely killed by repeated sprayings. AAAS is urged to set up an international research program on the…

Orians, Gordon H.; Pfeiffer, E. W.

1970-01-01

84

The role of deleterious mutations in allopatric speciation.  

PubMed

Allopatric speciation is often assumed to occur as a consequence of adaptive divergence between two isolated populations. However, there are some scenarios in which reproductive isolation can be favored due to accumulated unconditionally deleterious mutations. If deleterious mutations have synergistic epistatic effects, it is shown here that the average fitness of recombinants between two parental lines with a given number of fixed mutations is lower than that of the parents in both the F1 and F2 generations. If individual mutations are only slightly deleterious, then they will tend to fixation at a high enough rate to cause lower hybrid fitness. If the fitness effects of mutation give rise to antagonistic epistasis, the hybrids tend to have a higher average fitness than the parental lines, suggesting a possible scenario for the origin of hybrid vigor. The other model of deleterious mutations investigated is the accumulation of knockout mutants in a duplicated gene family. While neutral in the parental lines, upon contact the F1 and later generations have a significant probability of carrying double knockouts. Under this scenario, selection may also favor reproductive isolation between the two lines. Even when the selection coefficients generated are too low to drive speciation, epistatic interactions between deleterious mutations offer a possible explanation for both outbreeding depression and hybrid vigor. PMID:16153025

Shpak, Max

2005-07-01

85

Ecological and Evolutionary Effects of Stickleback on Community Structure  

PubMed Central

Species’ ecology and evolution can have strong effects on communities. Both may change concurrently when species colonize a new ecosystem. We know little, however, about the combined effects of ecological and evolutionary change on community structure. We simultaneously examined the effects of top-predator ecology and evolution on freshwater community parameters using recently evolved generalist and specialist ecotypes of three-spine stickleback (Gasterosteus aculeatus). We used a mesocosm experiment to directly examine the effects of ecological (fish presence and density) and evolutionary (phenotypic diversity and specialization) factors on community structure at lower trophic levels. We evaluated zooplankton biomass and composition, periphyton and phytoplankton chlorophyll-a concentration, and net primary production among treatments containing different densities and diversities of stickleback. Our results showed that both ecological and evolutionary differences in the top-predator affect different aspects of community structure and composition. Community structure, specifically the abundance of organisms at each trophic level, was affected by stickleback presence and density, whereas composition of zooplankton was influenced by stickleback diversity and specialization. Primary productivity, in terms of chlorophyll-a concentration and net primary production was affected by ecological but not evolutionary factors. Our results stress the importance of concurrently evaluating both changes in density and phenotypic diversity on the structure and composition of communities.

Des Roches, Simone; Shurin, Jonathan B.; Schluter, Dolph; Harmon, Luke J.

2013-01-01

86

[Effect of ecological factors on citrus fruit quality].  

PubMed

This paper summarized the research advance on the physiological foundation of citrus fruit's major quality factors such as color formation and organic acid and sugar accumulation, and analyzed the effects of main ecological factors such as temperature, sunshine, water, soil, terrain and landforms on them. The existing problems and the research prospects of citrus ecology were expounded, and a useful proposal on the quality sub-distribution of citrus in China was put forward. PMID:15574012

Bao, Jiangfeng; Xia, Renxue; Peng, Shu'ang

2004-08-01

87

Nature of deleterious mutation load in Drosophila.  

PubMed

Much population genetics and evolution theory depends on knowledge of genomic mutation rates and distributions of mutation effects for fitness, but most information comes from a few mutation accumulation experiments in Drosophila in which replicated chromosomes are sheltered from natural selection by a balancer chromosome. I show here that data from these experiments imply the existence of a large class of minor viability mutations with approximately equivalent effects. However, analysis of the distribution of viabilities of chromosomes exposed to EMS mutagenesis reveals a qualitatively different distribution of effects lacking such a minor effects class. A possible explanation for this difference is that transposable element insertions, a common class of spontaneous mutation event in Drosophila frequently generate minor viability effects. This explanation would imply that current estimates of deleterious mutation rates are not generally applicable in evolutionary models, as transposition rates vary widely. Alternatively, much of the apparent decline in viability under spontaneous mutation accumulation could have been nonmutational, perhaps due to selective improvement of balancer chromosomes. This explanation accords well with the data and implies a spontaneous mutation rate for viability two orders of magnitude lower than previously assumed, with most mutation load attributable to major effects. PMID:8978082

Keightley, P D

1996-12-01

88

Nonequilibrium model for estimating parameters of deleterious mutations  

NASA Astrophysics Data System (ADS)

Deleterious mutations are of extreme evolutionary importance because, even though they are eliminated by natural selection, their continuous pressure creates a pool of variability in natural populations. They are of potential relevance for the existence of several features in evolution, such as sexual reproduction, and pose a risk to small asexual populations. Despite their extreme importance, the deleterious mutation rate and the effects of each mutation on fitness are poorly known quantities. Here we analyze a simple model that can be applied to simple experiments, in microorganisms, aiming at the quantification of these values.

Gordo, Isabel; Dionisio, Francisco

2005-03-01

89

Overview of climate information needs for ecological effects models  

SciTech Connect

Atmospheric scientists engaged in climate change research require a basic understanding of how ecological effects models incorporate climate. The report provides an overview of existing ecological models that might be used to model climate change effects on vegetation. Some agricultural models and statistical methods are also discussed. The weather input data requirements, weather simulation methods, and other model characteristics relevant to climate change research are described for a selected number of models. The ecological models are classified as biome, ecosystem, or tree models; the ecosystem models are further subdivided into species dynamics or process models. In general, ecological modelers have had to rely on readily available meteorological data such as temperature and rainfall. Although models are becoming more sophisticated in their treatment of weather and require more kinds of data (such as wind, solar radiation, or potential evapotranspiration), modelers are still hampered by a lack of data for many applications. Future directions of ecological effects models and the climate variables that will be required by the models are discussed.

Peer, R.L.

1990-01-01

90

Community ecology as a framework for predicting contaminant effects  

Microsoft Academic Search

Most ecosystems receive an assortment of anthropo- genic chemicals from the thousands possible, making it important to identify a predictive theory for their direct andindirecteffects.Here,weproposethat theimpactsof contaminants can be simplified and unified under the framework of community ecology. This approach offers predictions of the strength and direction of indirect effects, which species are crucial for propagating these effects, which communities

Jason R. Rohr; Jacob L. Kerby; Andrew Sih

2006-01-01

91

ECOLOGICAL EFFECTS OF NITROGEN DEPOSITION IN THE WESTERN UNITED STATES  

EPA Science Inventory

Article synthesizes existing studies (biological, ecological, biogeochemical) on the effects of nitrogen deposition to aquatic and terrestrial ecosystems in the western United States. In the western U.S, vast acreages of land are exposed to low levels of atmospheric deposition, w...

92

Indirect Effects in Aquatic Ecotoxicology: Implications for Ecological Risk Assessment  

Microsoft Academic Search

Understanding toxicant effects at higher levels of biological organization continues to be a challenge in ecotoxicology and\\u000a ecological risk assessment. This is due in part to a tradition in ecotoxicology of considering the direct effects of toxicants\\u000a on a limited number of model test species. However, the indirect effects of toxicity may be a significant factor influencing\\u000a the manner in

BENJAMIN L. PRESTON; Wilson Boulevard

2002-01-01

93

Topical curcumin can inhibit deleterious effects of upper respiratory tract bacteria on human oropharyngeal cells in vitro: potential role for patients with cancer therapy induced mucositis?  

Microsoft Academic Search

Purpose  Curcumin exerts its anti-inflammatory activity via inhibition of nuclear factor ?B. Oropharyngeal epithelia and residing bacteria\\u000a closely interact in inflammation and infection. This in vitro model investigated the effects of curcumin on bacterial survival,\\u000a adherence to, and invasion of upper respiratory tract epithelia, and studied its anti-inflammatory effect. We aimed to establish\\u000a a model, which could offer insights into the

Sonja Lüer; Rolf Troller; Marion Jetter; Violeta Spaniol; Christoph Aebi

2011-01-01

94

Bilateral high-frequency stimulation of the subthalamic nucleus on attentional performance: transient deleterious effects and enhanced motivation in both intact and parkinsonian rats  

Microsoft Academic Search

It is now well established that subthalamic nucleus high-frequency stimulation (STN HFS) alleviates motor problems in Parkinson's disease. However, its efficacy for cognitive function remains a matter of debate. The aim of this study was to assess the effects of STN HFS in rats performing a visual attentional task. Bilateral STN HFS was applied in intact and in bilaterally dopamine

Christelle Baunez; Anastasia Christakou; Yogita Chudasama; Claude Forni; Trevor W. Robbins

95

Experiments on the role of deleterious mutations as stepping stones in adaptive evolution.  

PubMed

Many evolutionary studies assume that deleterious mutations necessarily impede adaptive evolution. However, a later mutation that is conditionally beneficial may interact with a deleterious predecessor before it is eliminated, thereby providing access to adaptations that might otherwise be inaccessible. It is unknown whether such sign-epistatic recoveries are inconsequential events or an important factor in evolution, owing to the difficulty of monitoring the effects and fates of all mutations during experiments with biological organisms. Here, we used digital organisms to compare the extent of adaptive evolution in populations when deleterious mutations were disallowed with control populations in which such mutations were allowed. Significantly higher fitness levels were achieved over the long term in the control populations because some of the deleterious mutations served as stepping stones across otherwise impassable fitness valleys. As a consequence, initially deleterious mutations facilitated the evolution of complex, beneficial functions. We also examined the effects of disallowing neutral mutations, of varying the mutation rate, and of sexual recombination. Populations evolving without neutral mutations were able to leverage deleterious and compensatory mutation pairs to overcome, at least partially, the absence of neutral mutations. Substantially raising or lowering the mutation rate reduced or eliminated the long-term benefit of deleterious mutations, but introducing recombination did not. Our work demonstrates that deleterious mutations can play an important role in adaptive evolution under at least some conditions. PMID:23918358

Covert, Arthur W; Lenski, Richard E; Wilke, Claus O; Ofria, Charles

2013-08-05

96

Reversal of the deleterious effects of chronic dietary HFCS-55 intake by PPAR-? agonism correlates with impaired NLRP3 inflammasome activation.  

PubMed

Although high-fructose corn syrup (HFCS-55) is the major sweetener in foods and soft-drinks, its potential role in the pathophysiology of diabetes and obesity ("diabesity") remains unclear. Peroxisome-proliferator activated receptor (PPAR)-? agonists have never been tested in models of sugar-induced metabolic abnormalities. This study was designed to evaluate (i) the metabolic and renal consequences of HFCS-55 administration (15% wt/vol in drinking water) for 30 weeks on male C57Bl6/J mice and (ii) the effects of the selective PPAR-? agonist GW0742 (1 mg/kg/day for 16 weeks) in this condition. HFCS-55 caused (i) hyperlipidemia, (ii) insulin resistance, and (iii) renal injury/inflammation. In the liver, HFCS-55 enhanced the expression of fructokinase resulting in hyperuricemia and caused abnormalities in known insulin-driven signaling events. In the kidney, HFCS-55 enhanced the expression of the NLRP3 (nucleotide-binding domain and leucine-rich-repeat-protein 3) inflammasome complex, resulting in caspase-1 activation and interleukin-1? production. All of the above effects of HFCS-55 were attenuated by the specific PPAR-? agonist GW0742. Thus, we demonstrate for the first time that the specific PPAR-? agonist GW0742 attenuates the metabolic abnormalities and the renal dysfunction/inflammation caused by chronic HFCS-55 exposure by preventing upregulation of fructokinase (liver) and activation of the NLRP3 inflammasome (kidney). PMID:23103566

Collino, Massimo; Benetti, Elisa; Rogazzo, Mara; Mastrocola, Raffaella; Yaqoob, Muhammed M; Aragno, Manuela; Thiemermann, Christoph; Fantozzi, Roberto

2012-10-24

97

Pulmonary Surfactant Protein SP-C Counteracts the Deleterious Effects of Cholesterol on the Activity of Surfactant Films under Physiologically Relevant Compression-Expansion Dynamics  

PubMed Central

Abstract The presence of cholesterol is critical in defining a dynamic lateral structure in pulmonary surfactant membranes. However, an excess of cholesterol has been associated with impaired surface activity of surfactant. It has also been reported that surfactant protein SP-C interacts with cholesterol in lipid/protein interfacial films. In this study, we analyzed the effect of SP-C on the thermodynamic properties of phospholipid membranes containing cholesterol, and the ability of lipid/protein complexes containing cholesterol to form and respread interfacial films capable of producing very low surface tensions upon repetitive compression-expansion cycling. SP-C modulates the effect of cholesterol to reduce the enthalpy associated with the gel-to-liquid-crystalline melting transition in dipalmitoylphosphatidylcholine (DPPC) bilayers, as analyzed by differential scanning calorimetry. The presence of SP-C affects more subtly the effects of cholesterol on the thermotropic properties of ternary membranes, mimicking more closely the lipid composition of native surfactant, where SP-C facilitates the miscibility of the sterol. Incorporation of 1% or 2% SP-C (protein/phospholipid by weight) promotes almost instantaneous adsorption of suspensions of DPPC/palmitoyloleoylphospatidylcholine (POPC)/palmitoyloleoyl-phosphatidylglycerol (POPG) (50:25:15, w/w/w) into the air-liquid interface of a captive bubble, in both the absence and presence of cholesterol. However, cholesterol impairs the ability of SP-C-containing films to achieve very low surface tensions in bubbles subjected to compression-expansion cycling. Cholesterol also substantially impairs the ability of DPPC/POPC/POPG films containing 1% surfactant protein SP-B to mimic the interfacial behavior of native surfactant films, which are characterized by very low minimum surface tensions with only limited area change during compression and practically no compression-expansion hysteresis. However, the simultaneous presence of 2% SP-C practically restores the compression-expansion dynamics of cholesterol- and SP-B-containing films to the efficient behavior shown in the absence of cholesterol. This suggests that cooperation between the two proteins is required for lipid-protein films containing cholesterol to achieve optimal performance under physiologically relevant compression-expansion dynamics.

Gomez-Gil, Leticia; Schurch, David; Goormaghtigh, Erik; Perez-Gil, Jesus

2009-01-01

98

StarD4-mediated translocation of 7-hydroperoxycholesterol to isolated mitochondria: deleterious effects and implications for steroidogenesis under oxidative stress conditions.  

PubMed

StAR family proteins, including StarD4, play a key role in steroidogenesis by transporting cholesterol (Ch) into mitochondria for conversion to pregnenolone. Using a model system consisting of peroxidized cholesterol (7 alpha-OOH)-containing liposomes as donors, we showed that human recombinant StarD4 accelerates 7 alpha-OOH transfer to isolated liver mitochondria, and to a greater extent than Ch transfer. StarD4 had no effect on transfer of non-oxidized or peroxidized phosphatidylcholine, consistent with sterol ring specificity. StarD4-accelerated 7 alpha-OOH transfer to mitochondria resulted in greater susceptibility to free radical lipid peroxidation and loss of membrane potential than in a non-StarD4 control. The novel implication of these findings is that in oxidative stress states, inappropriate StAR-mediated trafficking of peroxidized Ch in steroidogenic tissues could result in damage and dysfunction selectively targeted to mitochondria. PMID:20059974

Korytowski, Witold; Rodriguez-Agudo, Daniel; Pilat, Anna; Girotti, Albert W

2010-01-06

99

StarD4-mediated Translocation of 7-Hydroperoxycholesterol to Isolated Mitochondria: Deleterious Effects and Implications for Steroidogenesis Under Oxidative Stress Conditions  

PubMed Central

StAR family proteins, including StarD4, play a key role in steroidogenesis by transporting cholesterol (Ch) into mitochondria for conversion to pregnenolone. Using a model system consisting of peroxidized cholesterol (7?-OOH)-containing liposomes as donors, we showed that human recombinant StarD4 accelerates 7?-OOH transfer to isolated liver mitochondria, and to a greater extent than Ch transfer. StarD4 had no effect on transfer of non-oxidized or peroxidized phosphatidylcholine, consistent with sterol ring specificity. StarD4-accelerated 7?-OOH transfer to mitochondria resulted in greater susceptibility to free radical lipid peroxidation and loss of membrane potential than in a non-StarD4 control. The novel implication of these findings is that in oxidative stress states, inappropriate StAR-mediated trafficking of peroxidized Ch in steroidogenic tissues could result in damage and dysfunction selectively targeted to mitochondria.

Korytowski, Witold; Rodriguez-Agudo, Daniel; Pilat, Anna; Girotti, Albert W.

2010-01-01

100

Deleterious Effect of the Qo Inhibitor Compound Resistance-Conferring Mutation G143A in the Intron-Containing Cytochrome b Gene and Mechanisms for Bypassing It? †  

PubMed Central

The mutation G143A in the inhibitor binding site of cytochrome b confers a high level of resistance to fungicides targeting the bc1 complex. The mutation, reported in many plant-pathogenic fungi, has not evolved in fungi that harbor an intron immediately after the codon for G143 in the cytochrome b gene, intron bi2. Using Saccharomyces cerevisiae as a model organism, we show here that a codon change from GGT to GCT, which replaces glycine 143 with alanine, hinders the splicing of bi2 by altering the exon/intron structure needed for efficient intron excision. This lowers the levels of cytochrome b and respiratory growth. We then investigated possible bypass mechanisms that would restore the respiratory fitness of a resistant mutant. Secondary mutations in the mitochondrial genome were found, including a point mutation in bi2 restoring the correct exon/intron structure and the deletion of intron bi2. We also found that overexpression of nuclear genes MRS2 and MRS3, encoding mitochondrial metal ion carriers, partially restores the respiratory growth of the G143A mutant. Interestingly, the MRS3 gene from the plant-pathogenic fungus Botrytis cinerea, overexpressed in an S. cerevisiae G143A mutant, had a similar compensatory effect. These bypass mechanisms identified in yeast could potentially arise in pathogenic fungi.

Vallieres, Cindy; Trouillard, Martin; Dujardin, Genevieve; Meunier, Brigitte

2011-01-01

101

Epstein-Barr virus protein EB2 stimulates cytoplasmic mRNA accumulation by counteracting the deleterious effects of SRp20 on viral mRNAs.  

PubMed

The Epstein-Barr Virus (EBV) protein EB2 (also called Mta, SM and BMLF1), is an essential nuclear protein produced during the replicative cycle of EBV. EB2 is required for the efficient cytoplasmic accumulation of viral mRNAs derived from intronless genes. EB2 is an RNA-binding protein whose expression has been shown to influence RNA stability, splicing, nuclear export and translation. Using a yeast two-hybrid screen, we have identified three SR proteins, SF2/ASF, 9G8 and SRp20, as cellular partners of EB2. Then, by using siRNA to deplete cells of specific SR proteins, we found that SRp20 plays an essential role in the processing of several model mRNAs: the Renilla luciferase reporter mRNA, the human ?-globin cDNA transcript and two EBV late mRNAs. These four mRNAs were previously found to be highly dependent on EB2 for their efficient cytoplasmic accumulation. Here, we show that SRp20 depletion results in an increase in the accumulation of these mRNAs, which correlates with an absence of additive effect of EB2, suggesting that EB2 functions by antagonizing SRp20. Moreover, by using RNA-immunoprecipitation assays we found that EB2 enhances the association of SRp20 with the ?-globin transcript suggesting that EB2 acts by stabilizing SRp20's labile interactions with the RNA. PMID:22505578

Juillard, Franceline; Bazot, Quentin; Mure, Fabrice; Tafforeau, Lionel; Macri, Christophe; Rabourdin-Combe, Chantal; Lotteau, Vincent; Manet, Evelyne; Gruffat, Henri

2012-04-13

102

Environmental concentrations of irgarol, diuron and S-metolachlor induce deleterious effects on gametes and embryos of the Pacific oyster, Crassostrea gigas.  

PubMed

Irgarol and diuron are the most representative "organic booster biocides" that replace organotin compounds in antifouling paints, and metolachlor is one of the most extensively used chloroacetamide herbicides in agriculture. The toxicity of S-metolachlor, irgarol and diuron was evaluated in Pacific oyster (Crassostrea gigas) gametes or embryos exposed to concentrations of pesticides ranging from 0.1× to 1000×, with 1× corresponding to environmental concentrations of the three studied pesticides in Arcachon Bay (France). Exposures were performed on (1) spermatozoa alone (2) oocytes alone and (3) both spermatozoa and oocytes, and adverse effects on fertilization success and offspring development were recorded. The results showed that the fertilizing capacity of spermatozoa was significantly affected after gamete exposure to pesticide concentrations as low as 1× of irgarol and diuron and 10× of metolachlor. The offspring obtained from pesticide-exposed spermatozoa displayed a dose-dependent increase in developmental abnormalities. In contrast, treating oocytes with pesticide concentrations up to 10× did not alter fertilization rate and offspring quality. However, a significant decline in fertilization success and increase in abnormal D-larvae prevalence were observed at higher concentrations 10× (0.1 ?g L(-1)) for S-metolachlor and 100× for irgarol (1.0 ?g L(-1)) and diuron (4.0 ?g L(-1)). Irgarol, diuron and S-metolachlor also induced a dose-dependent increase in abnormal D-larvae prevalence when freshly fertilized embryos were treated with pesticide concentrations as low as concentration of 1× (0.01 ?g L(-1) for irgarol or S-metolachlor, and 0.04 ?g L(-1) for diuron). The two bioassays on C. gigas spermatozoa and embryos displayed similar sensitivities to the studied pesticides while oocytes were less sensitive. Diuron, irgarol and S-metolachlor induced spermiotoxicity and embryotoxicity at environmentally relevant concentrations and therefore might be a threat to oyster recruitment in coastal areas facing chronic inputs of pesticides. PMID:23727205

Mai, Huong; Morin, Bénédicte; Pardon, Patrick; Gonzalez, Patrice; Budzinski, Hélène; Cachot, Jérôme

2013-05-09

103

Visual search in ecological and non-ecological displays: evidence for a non-monotonic effect of complexity on performance.  

PubMed

Considerable research has been carried out on visual search, with single or multiple targets. However, most studies have used artificial stimuli with low ecological validity. In addition, little is known about the effects of target complexity and expertise in visual search. Here, we investigate visual search in three conditions of complexity (detecting a king, detecting a check, and detecting a checkmate) with chess players of two levels of expertise (novices and club players). Results show that the influence of target complexity depends on level of structure of the visual display. Different functional relationships were found between artificial (random chess positions) and ecologically valid (game positions) stimuli: With artificial, but not with ecologically valid stimuli, a "pop out" effect was present when a target was visually more complex than distractors but could be captured by a memory chunk. This suggests that caution should be exercised when generalising from experiments using artificial stimuli with low ecological validity to real-life stimuli. PMID:23320084

Chassy, Philippe; Gobet, Fernand

2013-01-08

104

Ecological and socioeconomic effects of China's policies for ecosystem services.  

PubMed

To address devastating environmental crises and to improve human well-being, China has been implementing a number of national policies on payments for ecosystem services. Two of them, the Natural Forest Conservation Program (NFCP) and the Grain to Green Program (GTGP), are among the biggest programs in the world because of their ambitious goals, massive scales, huge payments, and potentially enormous impacts. The NFCP conserves natural forests through logging bans and afforestation with incentives to forest enterprises, whereas the GTGP converts cropland on steep slopes to forest and grassland by providing farmers with grain and cash subsidies. Overall ecological effects are beneficial, and socioeconomic effects are mostly positive. Whereas there are time lags in ecological effects, socioeconomic effects are more immediate. Both the NFCP and the GTGP also have global implications because they increase vegetative cover, enhance carbon sequestration, and reduce dust to other countries by controlling soil erosion. The future impacts of these programs may be even bigger. Extended payments for the GTGP have recently been approved by the central government for up to 8 years. The NFCP is likely to follow suit and receive renewed payments. To make these programs more effective, we recommend systematic planning, diversified funding, effective compensation, integrated research, and comprehensive monitoring. Effective implementation of these programs can also provide important experiences and lessons for other ecosystem service payment programs in China and many other parts of the world. PMID:18621700

Liu, Jianguo; Li, Shuxin; Ouyang, Zhiyun; Tam, Christine; Chen, Xiaodong

2008-07-09

105

Estimating the likelihood of fallacious ecological inference: linear ecological regression in the presence of context effects  

Microsoft Academic Search

In situations where the only reliable data source is electoral data at the aggregate level for a geographic unit such as voting precincts, social scientists have sought to use ecological regression techniques to recreate the voting behavior of particular groups without committing the ecological fallacy of the sort warned of by Robinson (1950). Until quite recently, the most common use

Bernard Grofman

1997-01-01

106

Digital television's position and effect in the media ecology environment of broadcast and television  

Microsoft Academic Search

Various media owns its living space for its specific dissemination feature and ecological niche with special time and space. This article uses media ecology theory to study the effect and function of digital television on the living environment of television media, with the purpose of analyzing the change for the whole media ecology environment. With the application of basic analysis

Lun Liu

2010-01-01

107

Physiological Ecology of Freshwater Mussel Communities: Effects of Temperature on Community Structure and Ecological Services.  

NASA Astrophysics Data System (ADS)

Recent work suggests that freshwater mussel communities significantly influence stream ecosystem function through benthic-pelagic coupling of energy and nutrients. Mussel beds increase sediment organic matter and benthic algal production, facilitating the abundance and diversity of co-occurring benthic invertebrates. The magnitude of these effects appear to be regulated by abiotic factors such as temperature and flow, which influence hydraulic residence time and biological rates of reaction. We are using an integrative approach to examine the role of temperature on measures of physiological condition (metabolic rate, glycogen concentration, RNA: DNA) and measures of ecosystem services (nutrient excretion, biodeposition and clearance rate). Eight different species of unionids were removed from a mussel bed in the Little River, OK and acclimated to four temperatures (5, 15, 25, and 35C) for two weeks prior to the experiment. Measures of condition and ecosystem services were taken for all species at each temperature. Data collected to date suggest that there is significant variation in species-specific thermal performance. These performance curves influence resource acquisition, potentially shaping community structure (species dominance) and subsequent ecological function.

Spooner, D. E.; Vaughn, C. C.

2005-05-01

108

Ecological effects of the herbicide linuron in tropical freshwater microcosms.  

PubMed

Effects of a single application of the photosynthesis-inhibiting herbicide linuron (0, 15, 50, 150, and 500 microg/L) on the ecology of outdoor plankton-dominated microcosms were studied in Thailand. As a result of the decreased photosynthesis, DO and pH decreased while EC, alkalinity and nutrient concentrations increased. Chlorophytes belonging to the genera Scenedesmus, Coelastrum and Pediastrum were the most sensitive taxa, whereas several other chlorophytes, diatoms, and cryptophytes increased in abundance. Tolerant taxa appeared to be less digestable for several zooplankton taxa, which subsequently decreased in abundances. Chamaesiphon sp. (Cyanobacteria) was the most susceptible periphyton species. As a consequence of functional redundancy, effects of the herbicide on the chlorophyll-a content of periphyton and especially phytoplankton did not always reflect the effects noted on community level. PMID:18718661

Daam, Michiel A; Rodrigues, António M F; Van den Brink, Paul J; Nogueira, António J A

2008-08-20

109

Spatial heterogeneity in the strength of selection against deleterious alleles and the mutation load.  

PubMed

According to current estimates of genomic deleterious mutation rates (which are often of the order 0.1-1) the mutation load (defined as a reduction in the average fitness of a population due to the presence of deleterious alleles) may be important in many populations. In this paper, I use multilocus simulations to explore the effect of spatial heterogeneity in the strength of selection against deleterious alleles on the mutation load (for example, it has been suggested that stressful environments may increase the strength of selection). These simulations show contrasted results: in some situations, spatial heterogeneity may greatly reduce the mutation load, due to the fact that migrants coming from demes under stronger selection carry relatively few deleterious alleles, and benefit from a strong advantage within demes under weaker selection (where individuals carry many more deleterious alleles); in other situations, however, deleterious alleles accumulate within demes under stronger selection, due to migration pressure from demes under weaker selection, leading to fitness erosion within those demes. This second situation is more frequent when the productivity of the different demes is proportional to their mean fitness. The effect of spatial heterogeneity is greatly reduced, however, when the response to environmental differences is inconsistent across loci. PMID:22588129

Roze, D

2012-05-16

110

Land use Dynamic Changes and Ecological Effect in Jiaodong Region, China  

Microsoft Academic Search

Land use dynamic changes and ecological effect are the core content in the land use\\/cover research?» and case research is one of the important research methods for Land use dynamic changes and ecological effect. This paper take the Jiaodong region of China as a research case, and study systemically the rule of land use dynamic changes and its effects on

Jia Wen-chen; Wang Juan-le; Sun Chong-liang

2008-01-01

111

Biogeochemical and Ecological Effects of Nitrogen Deposition in Western North America  

NASA Astrophysics Data System (ADS)

The unique geographic, demographic, climatic and edaphic conditions of the West determine N deposition rates and biogeochemical and ecological responses to N deposition. In the western United States large regions are exposed to low N deposition levels with interspersed hotspots of elevated N deposition near urban areas or large agricultural emissions sources. Nitrogen emissions also contribute to ozone formation and regional haze and visibility impairment, the latter an effect that is observed in remote sites including several high profile national parks and wilderness areas. Recent studies suggest that N enrichment impacts are generally more important in western terrestrial systems than soil acidification effects. In the Pacific Northwest, California and Colorado sensitive organisms such as lichens and phytoplankton demonstrate deleterious biological effects with N deposition levels as low as 3-8 kg ha-1 yr-1. Increased streamwater nitrate export has been reported from southern California forests and chaparral catchments, high elevation watersheds in the Colorado Front Range, and in the most exposed regions of the southwestern Sierra Nevada. Evidence suggests that in some regions N deposition alters plant community composition, decreases mycorrhizal diversity, and also increases biomass accumulation, carbon allocation patterns and fire frequency. Several factors predispose Western semiarid ecosystems to N saturation as will be demonstrated by the San Bernardino Mountains case study (southern California). Edaphic conditions generally favor high nitrification rates relative to N mineralization. Nitrate from nitrification and atmospheric deposition accumulates in soil and on plant surfaces during prolonged dry periods. Under conditions of chronic N deposition, the N cycle becomes highly open in nature as excess N is exported in runoff and as gaseous emissions from soil. Actively nitrifying soils and temporal asynchrony between the period of plant N demand and nitrate availability are the key factors resulting in large N losses. As a result of this asynchrony, N limitation of tree growth occurs notwithstanding the advanced degree of N saturation. The combined effects of ozone and N deposition also cause major changes in plant carbon allocation and accumulation in the ecosystem, particularly under conditions of fire suppression.

Fenn, M. E.

2003-12-01

112

Nontarget effects of an introduced biological control agent on deer mouse ecology  

Microsoft Academic Search

Release of exotic insects as biological control agents is a common approach to controlling exotic plants. Though controversy\\u000a has ensued regarding the deleterious direct effects of biological control agents to non-target species, few have examined\\u000a the indirect effects of a ”well-behaved” biological control agent on native fauna. We studied a grassland in west-central\\u000a Montana infested with spotted knapweed (Centaurea maculosa)

Dean E. Pearson; Kevin S. McKelvey; Leonard F. Ruggiero

2000-01-01

113

16 Assortative Mating and Speciation as Pleiotropic Effects of Ecological Adaptation: Examples in Moths and Butterflies  

Microsoft Academic Search

Where divergent ecological adaptation also leads to assortative mating between populations, speciation is facilitated. We have extensively studied two examples from among the Lepidoptera, in which ecologically selected traits have pleiotropic effects on the mating system. Based on our understanding of mating behaviour and pleiotropy derived from these empirical examples, we here review pleiotropic effects in speciation and propose a

CHRIS D. JIGGINS; IGOR EMELIANOV; JAMES MALLET

114

THE LOCAL EFFECT TIME (LET) AND HOW IT INCORPORATES ECOLOGY INTO RESIDENCE TIME  

EPA Science Inventory

A clear and direct connection between constituent/water residence times and ecological effects is necessary to quantitatively relate these time scales to ecology. The concept of "local effect time" (LET) is proposed here as a time scale with adequate spatial resolution to relate ...

115

Evidence for Hitchhiking of Deleterious Mutations within the Human Genome  

PubMed Central

Deleterious mutations present a significant obstacle to adaptive evolution. Deleterious mutations can inhibit the spread of linked adaptive mutations through a population; conversely, adaptive substitutions can increase the frequency of linked deleterious mutations and even result in their fixation. To assess the impact of adaptive mutations on linked deleterious mutations, we examined the distribution of deleterious and neutral amino acid polymorphism in the human genome. Within genomic regions that show evidence of recent hitchhiking, we find fewer neutral but a similar number of deleterious SNPs compared to other genomic regions. The higher ratio of deleterious to neutral SNPs is consistent with simulated hitchhiking events and implies that positive selection eliminates some deleterious alleles and increases the frequency of others. The distribution of disease-associated alleles is also altered in hitchhiking regions. Disease alleles within hitchhiking regions have been associated with auto-immune disorders, metabolic diseases, cancers, and mental disorders. Our results suggest that positive selection has had a significant impact on deleterious polymorphism and may be partly responsible for the high frequency of certain human disease alleles.

Chun, Sung; Fay, Justin C.

2011-01-01

116

Ecological and Evolutionary Effects of Dispersal on Freshwater Zooplankton  

ERIC Educational Resources Information Center

|A recent focus on contemporary evolution and the connections between communities has sought to more closely integrate ecology with evolutionary biology. Studies of coevolutionary dynamics, life history evolution, and rapid local adaptation demonstrate that ecological circumstances can dictate evolutionary trajectories. Thus, variation in species…

Allen, Michael R.

2009-01-01

117

Ecological effects of soil contamination at Aberdeen Proving Ground, Maryland  

Microsoft Academic Search

Assessment of the ecological condition of contaminated soil was conducted in portions of the U.S. Army's Aberdeen Proving Ground, Maryland as part of an ecological risk assessment. This area is covered by open fields, woods and nontidal marshes. Chemicals disposed of in open burning pits included methylphosphonothioic acid, dichlorodiethyl sulfide, and titanium tetrachloride and sulfur trioxide\\/chlorosulfonic acid. Previous soil analysis

R. G. Kuperman; C. P. Dunn

1994-01-01

118

Effects of nondifferential exposure misclassification in ecologic studies.  

PubMed

Although many authors have argued against inferring individual-level exposure-disease relations from ecologic data because of the potential "ecological fallacy." the availability of data from diverse populations promotes the continued use of this rapid and inexpensive study design. In ecologic studies, the exposure status of groups is often defined by the proportion of individuals exposed. In these studies, nondifferential exposure misclassification of individuals is shown to produce overestimation of exposure-disease associations that may be extreme when the ecologically derived rate ratios are applied to individuals. This overestimation contrasts with the bias toward the null resulting from nondifferential misclassification of a binary exposure in epidemiologic studies conducted at the individual level. Given the magnitude of the potential bias from nondifferential exposure misclassification and other sources, quantitative estimates of individual-level rate ratios from ecologic data should be interpreted with extreme caution. PMID:1736664

Brenner, H; Savitz, D A; Jöckel, K H; Greenland, S

1992-01-01

119

Priming effect: bridging the gap between terrestrial and aquatic ecology.  

PubMed

Understanding how ecosystems store or release carbon is one of ecology's greatest challenges in the 21st century. Organic matter covers a large range of chemical structures and qualities, and it is classically represented by pools of different recalcitrance to degradation. The interaction effects of these pools on carbon cycling are still poorly understood and are most often ignored in global-change models. Soil scientists have shown that inputs of labile organic matter frequently tend to increase, and often double, the mineralization of the more recalcitrant organic matter. The recent revival of interest for this phenomenon, named the priming effect, did not cross the frontiers of the disciplines. In particular, the priming effect phenomenon has been almost totally ignored by the scientific communities studying marine and continental aquatic ecosystems. Here we gather several arguments, experimental results, and field observations that strongly support the hypothesis that the priming effect is a general phenomenon that occurs in various terrestrial, freshwater, and marine ecosystems. For example, the increase in recalcitrant organic matter mineralization rate in the presence of labile organic matter ranged from 10% to 500% in six studies on organic matter degradation in aquatid ecosystems. Consequently, the recalcitrant organic matter mineralization rate may largely depend on labile organic matter availability, influencing the CO2 emissions of both aquatic and terrestrial ecosystems. We suggest that (1) recalcitrant organic matter may largely contribute to the CO2 emissions of aquatic ecosystems through the priming effect, and (2) priming effect intensity may be modified by global changes, interacting with eutrophication processes and atmospheric CO2 increases. Finally, we argue that the priming effect acts substantially in the carbon and nutrient cycles in all ecosystems. We outline exciting avenues for research, which could provide new insights on the responses of ecosystems to anthropogenic perturbations and their feedbacks to climatic changes. PMID:21058546

Guenet, Bertrand; Danger, Michael; Abbadie, Luc; Lacroix, Gérard

2010-10-01

120

Quantitative analysis of ecological effects for land use planning based on ecological footprint method: a case research in Nanyang City  

NASA Astrophysics Data System (ADS)

The research of coordinated development between land use and ecological building is a new problem with the development of country economy, whose intention is to improve economy development and protect eco-environment in order to realize regional sustainable development. Evaluating human effects on the ecosystem by a comprehensive, scientific and quantitative method is a critical issue in the process of general land use planning. At present, ecological footprint methodology, as an excellent educational tool applicable to global issues, is essential for quantifying humanity's consumption of natural capital, for overall assessments of human impact on earth as well as for general land use planning. However, quantitative studies on the development trends of ecological footprint (EF) time series and biological capacity (BC) time series in a given region are still rare. Taking Nanyang City as a case study, this paper presents two quantitative estimate indices over time scale called the change rate and scissors difference to quantitatively analyze the trends of EF and BC over the planning period in general land use planning form 1997-2004 and to evaluate the ecological effects of the land use general planning form 1997 to.2010. The results showed that: 1 In Nanyang city, trends of the per capita EF and BC were on the way round, and the ecological deficit enhanced from 1997 to 2010. 2 The difference between the two development trends of per capita EF and BC had been increasing rapidly and the conflict between the EF and BC was aggravated from 1997 to 2010. 3 The general land use planning (1997 - 2010) of Nanyang city had produced some positive effects on the local ecosystem, but the expected biological capacity in 2010 can hardly be realized following this trend. Therefore, this paper introduces a "trinity" land use model in the guidelines of environment- friendly land use pattern and based on the actual situation of Nanyang city, with the systemic synthesis of land utilization of the cities, the village and the suburb as a principal part and the land development reorganization and the ecological environment construction as the key point.

Zhang, Jing; Liu, Yaolin; Chen, Xinming

2008-10-01

121

Ecological effects of oil shale development: problems, perspectives, and approaches  

SciTech Connect

Although current oil shale developments in the Piceance Basin appear to have had little impact on ecosystems, it is important to recognize that planned expansion of the industry in the Basin will greatly magnify the potential for serious perturbations of the Piceance environs. The relatively small scale of the present oil shale activities in the Basin provides the biologist with a unique opportunity to establish and conduct quantitative studies designed to measure impacts as they occur. This paper is intended to focus attention on some of the problems, perspectives and recommended approaches to conducting ecosystem effects studies that will provide criteria for evaluation and mitigation of impacts should they occur. The purpose of this paper is not to criticize past and current environmental studies on oil shale, but in light of anticipated growth of the industry, to focus attention on the need to carefully define, design and execute ecological effects studies to quantify and provide mitigation criteria for impacts that will undoubtedly result from accelerated industry activities.

Hakonson, T.E.; White. G.C.

1980-01-01

122

Biomarker-based biomonitoring for evaluating health and ecological effects on environmental contamination  

Microsoft Academic Search

This paper describes a research approach for assessing the biological and ecological significance of contaminants present in the environment. The approach uses wild animals and introduced caged animals near hazardous waste sites as (1) sentinels of bioavailable contaminants, (2) predictors of adverse ecological effects, and (3) surrogates to estimate the potential exposure and risks to humans living near these sites.

J. F. McCarthy; L. R. Shugart; B. D. Jimenez

1991-01-01

123

Sexual selection against deleterious mutations via variable male search success  

PubMed Central

In many species, successful mating requires the initial step of actively searching for and locating a female. The overall health or condition of a male is likely to affect their ability to do this, making search effort a potentially important component of sexual fitness that may have important consequences for population mean fitness. We investigated the potential population genetic consequences of search effort using 10 populations of Drosophila melanogaster, each fixed for a different recessive mutation with a visible phenotypic effect. Mate choice trials were conducted in arenas of varying size, requiring different levels of search ability. Sexual selection against mutant males was stronger when increased search effort was included than when it was excluded. Varying abilities to find mates can substantially increase the strength of selection against deleterious alleles.

MacLellan, Kelsie; Whitlock, Michael C.; Rundle, Howard D.

2009-01-01

124

Groundwater Chemistry and Microbial Ecology Effects on Explosives Biodegradation.  

National Technical Information Service (NTIS)

The overall goal of this project was to gain a better understanding of the microbial ecology of explosives compound biodegradation in groundwater. Deciphering which organisms are involved with explosives degradation under various in situ conditions could ...

M. E. Fuller R. J. Steffan

2008-01-01

125

[Environmental behavior and ecological effect of polydimethylsiloxane: a review].  

PubMed

Polydimethylsiloxane (PDMS) is widely used in industrial products, medical and health care products, and personal care products. In the treatment process of sewage, PDMS can be hardly biodegraded but enter the environment mainly through the discharge of excess sludge, and only a small amount of PDMS adsorbed on the suspended solids or sludge particle surface is discharged into water body and sediment with treated sewage. There is no enough evidence to verify that PDMS can vertically migrate in sediment. The degradation of PDMS in sediment is very slow, but PDMS can be degraded in different types of soils. PDMS has less risk to aquatic ecosystem, and no apparent acute toxicity to benthos. In soil environment, PDMS and its degradation products have no significant effects on the soil microorganisms, soil animals, and crops. Though a few studies indicated that PDMS and its degradation products have relatively low ecological toxicity in various environments, it is still very important to clarify the potential threat of PDMS to the environment because of the increasingly large number of PDMS being produced and used. PMID:23189715

Yang, Shang-Yuan; Li, Xin; Yang, Jia; Shen, Chao-Feng; Yu, Hua-Dong; Lu, Kang

2012-08-01

126

Extraordinary Sex Ratios: Cultural Effects on Ecological Consequences  

PubMed Central

We model sex-structured population dynamics to analyze pairwise competition between groups differing both genetically and culturally. A sex-ratio allele is expressed in the heterogametic sex only, so that assumptions of Fisher’s analysis do not apply. Sex-ratio evolution drives cultural evolution of a group-associated trait governing mortality in the homogametic sex. The two-sex dynamics under resource limitation induces a strong Allee effect that depends on both sex ratio and cultural trait values. We describe the resulting threshold, separating extinction from positive growth, as a function of female and male densities. When initial conditions avoid extinction due to the Allee effect, different sex ratios cannot coexist; in our model, greater female allocation always invades and excludes a lesser allocation. But the culturally transmitted trait interacts with the sex ratio to determine the ecological consequences of successful invasion. The invading female allocation may permit population persistence at self-regulated equilibrium. For this case, the resident culture may be excluded, or may coexist with the invader culture. That is, a single sex-ratio allele in females and a cultural dimorphism in male mortality can persist; a low-mortality resident trait is maintained by father-to-son cultural transmission. Otherwise, the successfully invading female allocation excludes the resident allele and culture and then drives the population to extinction via a shortage of males. Finally, we show that the results obtained under homogeneous mixing hold, with caveats, in a spatially explicit model with local mating and diffusive dispersal in both sexes.

Molnar, Ferenc; Caraco, Thomas; Korniss, Gyorgy

2012-01-01

127

Estimate of the genomic mutation rate deleterious to overall fitness in E. coll  

NASA Astrophysics Data System (ADS)

MUTATIONS are a double-edged sword: they are the ultimate source of genetic variation upon which evolution depends, yet most mutations affecting fitness (viability and reproductive success) appear to be harmful1. Deleterious mutations of small effect can escape natural selection, and should accumulate in small populations2-4. Reduced fitness from deleterious-mutation accumulation may be important in the evolution of sex5-7, mate choice8,9, and diploid life-cycles10, and in the extinction of small populations11,12. Few empirical data exist, however. Minimum estimates of the genomic deleterious-mutation rate for viability in Drosophila melanogaster are surprisingly high1,13,14, leading to the conjecture that the rate for total fitness could exceed 1.0 mutation per individual per generation5,6. Here we use Escherichia coli to provide an estimate of the genomic deleterious-mutation rate for total fitness in a microbe. We estimate that the per-microbe rate of deleterious mutations is in excess of 0.0002.

Kibota, Travis T.; Lynch, Michael

1996-06-01

128

Cascading climate effects and related ecological consequences during past centuries  

NASA Astrophysics Data System (ADS)

The interface between climate and ecosystem structure and function is incompletely understood, partly because few ecological records start before the recent warming phase. Here, we analyse an exceptional 100-yr long record of the great tit (Parus major) population in Switzerland in relation to climate and habitat phenology. Using path analysis, we demonstrate an uninterrupted cascade of significant influences of the large-scale atmospheric circulation (North-Atlantic Oscillation, NAO, and North-sea - Caspian Pattern, NCP) on habitat and breeding phenology, and further on fitness-relevant life history traits within animal populations. We then apply the relationships of this analysis to reconstruct the circulation-driven component of fluctuations in great tit breeding phenology and population dynamics on the basis of new seasonal NAO and NCP indices back to 1500 AD. According to the path model, the multi-decadal oscillation of the atmospheric circulation likely led to substantial variation in habitat phenology, and consequently, tit population minima during the "Maunder Minimum" (1650-1720) and the Little Ice Age Type Event I (1810-1850). The warming since 1975 was not only related with a quick shift towards earlier breeding, but also with the highest productivity since 1500, and thus, an unprecedented increase of the population. A verification of the structural equation model against two independent data series corroborates that the retrospective model reliably depicts the major long-term NAO/NCP impact on ecosystem parameters. The results suggest a complex cascade of climate effects beginning at a global scale and ending at the level of individual life histories. This sheds light on how large scale climate conditions substantially affect major life-history parameters within a population, and thus influence key ecosystem parameters at the scale of centuries.

Naef-Daenzer, B.; Luterbacher, J.; Nuber, M.; Rutishauser, T.; Winkel, W.

2012-06-01

129

An Overview of Stream Ecological Responses to Urban Effects and Management Practices in New England  

EPA Science Inventory

Many recent studies have found large changes in ecological conditions related to small increases in watershed development. Future development and restoration practices will benefit from better documenting the effectiveness of management practices. We present (1) a brief summary o...

130

40 CFR 158.240 - Experimental use permit data requirements for ecological effects.  

Code of Federal Regulations, 2011 CFR

...Experimental use permit data requirements for ecological effects. All data for terrestrial nontarget organisms and aquatic nontarget organisms as described in § 158.243 must be submitted to support a request for an experimental use permit....

2011-07-01

131

40 CFR 158.240 - Experimental use permit data requirements for ecological effects.  

Code of Federal Regulations, 2012 CFR

...Experimental use permit data requirements for ecological effects. All data for terrestrial nontarget organisms and aquatic nontarget organisms as described in § 158.243 must be submitted to support a request for an experimental use permit....

2012-07-01

132

Ecological Effects of Weather Modification: A Problem Analysis.  

ERIC Educational Resources Information Center

|This publication reviews the potential hazards to the environment of weather modification techniques as they eventually become capable of producing large scale weather pattern modifications. Such weather modifications could result in ecological changes which would generally require several years to be fully evident, including the alteration of…

Cooper, Charles F.; Jolly, William C.

133

A study of deleterious gene structure in plants using Markov chain Monte Carlo.  

PubMed

The characteristics of deleterious genes have been of great interest in both theory and practice in genetics. Because of the complex genetic mechanism of these deleterious genes, most current studies try to estimate the overall magnitude of mortality effects on a population, which is characterized classically by the number of lethal equivalents. This number is a combination of several parameters, each of which has a distinct biological effect on genetic mortality. In conservation and breeding programs, it is important to be able to distinguish among different combinations of these parameters that lead to the same number of lethal equivalents, such as a large number of mildly deleterious genes or a few lethal genes, The ability to distinguish such parameter combinations requires more than one generation of mating. We propose a model for survival data from a two-generation mating experiment on the plant species Brassica rapa, and we enable inference with Markov chain Monte Carlo. This computational strategy is effective because a vast amount of missing genotype information must be accounted for. In addition to the lethal equivalents, the two-generation data provide separate information on the average intensity of mortality and the average number of deleterious genes carried by an individual. In our Markov chain Monte Carlo algorithm, we use a vector proposal distribution to overcome inefficiency of a single-site Gibbs sampler. Information about environmental effects is obtained from an outcrossing experiment conducted in parallel with the two-generation mating experiments. PMID:11318190

Lee, J K; Lascoux, M; Newton, M A; Nordheim, E V

1999-06-01

134

An Investigation of the Effectiveness of Computer Simulation Programs as Tutorial Tools for Teaching Population Ecology at University.  

ERIC Educational Resources Information Center

|Describes a study of the effectiveness of computer-simulation programs in enhancing biology students' familiarity with ecological modeling and concepts. Finds that computer simulations improved student comprehension of ecological processes expressed in mathematical form, but did not allow a full understanding of ecological concepts. Contains 28…

Korfiatis, K.; Papatheodorou, E.; Paraskevopoulous, S.; Stamou, G. P.

1999-01-01

135

Effects of ecological factors on radial growth and wood density components of sessile oak ( Quercus petraea Liebl.) in Northern France  

Microsoft Academic Search

Many studies have demonstrated that sessile oak (Quercus petraea Liebl.) wood density is related to ring width, but most have focused on within-tree variability and have never explored large ecological gradients. Other studies indicate that ring width is largely controlled by ecological factors. Hence it has been concluded that ecological factors have an effect on wood density, yet few studies

Laurent Bergès; Gérard Nepveu; Alain Franc

2008-01-01

136

Ecological effects of soil contamination at Aberdeen Proving Ground, Maryland  

SciTech Connect

Assessment of the ecological condition of contaminated soil was conducted in portions of the U.S. Army's Aberdeen Proving Ground, Maryland as part of an ecological risk assessment. This area is covered by open fields, woods and nontidal marshes. Chemicals disposed of in open burning pits included methylphosphonothioic acid, dichlorodiethyl sulfide, and titanium tetrachloride and sulfur trioxide/chlorosulfonic acid. Previous soil analysis showed extensive surface soil contamination with metals, nitrate, PCBs and pesticides. This assessment included characterizing soil biota, biologically-mediated processes in soil and aboveground biomass. Field surveys of the soil invertebrate communities showed significant reductions in the total abundance of animals, reductions in the abundance of several taxonomic and functional groups of soil invertebrates, and changes in the activity of epigeic arthropods in contaminated areas when compared with the local [open quotes]background[close quotes] area. Laboratory toxicity tests also demonstrated that microbial activity and success of egg hatching of ground beetle Harpalus pensylvanicus were reduced in contaminated soils. These results suggest that impacts to soil ecosystems should be explicitly considered in ecological risk assessment.

Kuperman, R.G.; Dunn, C.P. (Argonne National Laboratory, IL (United States))

1994-06-01

137

Effect of coal mining on regional ecological footprint based on GIS  

NASA Astrophysics Data System (ADS)

Coal mining has brought a plenty of benefit and matter for human kind, and greatly improved the development of economy and society. At the same time, however, it has also lead to the environment damage, which has affected the regional sustainable development. In this paper, we take the Luxi Coal Mine, Shandong Province as an example, based on the GIS, to study the effect on the sustainable development due to coal mining with the theory of ecological footprint. The research result show that coal mining inevitably affects the ecological footprint of coal mining area. In order to minimize the ecological deficit, measures shall be taken during coal mining period to reduce the environment damage by coal mining, adopting new reclamation method to protect the ecological producing land and avoiding cultivated land degraded.

Chen, Qiu-ji; Kong, Yun-feng; Zhang, Hong-bo

2006-10-01

138

Environmental effects of increased coal utilization: ecological effects of gaseous emissions from coal combustion.  

PubMed

This report is limited to an evaluation of the ecological and environmental effects of gaseous emissions and aerosols of various types which result from coal combustion. It deals with NOx, SOx, fine particulate, photochemical oxidant and acid precipitation as these pollutants affect natural and managed resources and ecosystems. Also, synergistic effects involving two or more pollutants are evaluated as well as ecosystem level effects of gaseous pollutants. There is a brief summary of the effects on materials and atmospheric visibility of increased coal combustion. The economic implications of ecological effects are identified to the extent they can be determined within acceptable limits. Aquatic and terrestrial effects are distinguished where the pollutants in question are clearly problems in both media. At present, acid precipitation is most abundant in the north central and northeastern states. Total SOx and NOx emissions are projected to remain high in these regions while increasing relatively more in the western than in the eastern regions of the country. A variety of ecological processes are affected and altered by air pollution. Such processes include community succession and retrogression, nutrient biogeochemical cycling, photosynthetic activity, primary and secondary productivity, species diversity and community stability. Estimates of the non health-related cost of air pollutants range from several hundred million dollars to $1.7 billion dollars per year. In general, these estimates include only those relatively easily measured considerations such as the known losses to cultivate crops from acute air pollution episodes or the cost of frequent repainting required as a result of air pollution. No substantial nationwide estimates of losses to forest productivity, natural ecosystem productivity which is tapped by domestic grazing animals and wildlife, and other significant dollar losses are available. PMID:44247

Glass, N R

1979-12-01

139

From roadkill to road ecology: A review of the ecological effects of roads  

Microsoft Academic Search

Transportation infrastructure affects the structure of ecosystems, the dynamics of ecosystem function, and has direct effects on ecosystem components, including their species composition. Clearly, the construction of transport lines results in the direct destruction and removal of existing ecosystems, and the reconfiguration of local landforms. However, transportation systems, and more specifically, roads, have a wide variety of primary, or direct,

Alisa W. Coffin

2007-01-01

140

Review of Ecological Effects of Roads on Terrestrial and Aquatic Communities  

Microsoft Academic Search

Roads are a widespread and increasing feature of most landscapes. We reviewed the scientific liter- ature on the ecological effects of roads and found support for the general conclusion that they are associated with negative effects on biotic integrity in both terrestrial and aquatic ecosystems. Roads of all kinds have seven general effects: mortality from road construction, mortality from collision

Stephen C. Trombulak; Christopher A. Frissell

2000-01-01

141

Warfare Ecology  

NSDL National Science Digital Library

Among human activities causing ecological change, war is both intensive and far-reaching. Yet environmental research related to warfare is limited in depth and fragmented by discipline. Here we (1) outline a field of study called "warfare ecology," (2) provide a taxonomy of warfare useful for organizing the field, (3) review empirical studies, and (4) propose research directions and policy implications that emerge from the ecological study of warfare. Warfare ecology extends to the three stages of warfare - preparations, war, and postwar activities - and treats biophysical and socioeconomic systems as coupled systems. A review of empirical studies suggests complex relationships between warfare and ecosystem change. Research needs include the development of theory and methods for examining the cascading effects of warfare on specific ecosystems. Policy implications include greater incorporation of ecological science into military planning and improved rehabilitation of postwar ecosystem services, leading to increased peace and security.

Gary E. Machlis (University of Idaho;); Thor Hanson (University of Idaho;)

2008-09-01

142

Effects of nitrogen fertiliser and pesticide management on floodwater ecology in a wetland ricefield  

Microsoft Academic Search

We investigated the effects of N fertiliser and pesticide applications on the population dynamics of benthic molluscs in a tropical wetland rice field. Populations were monitored for two consecutive dry seasons in selected treatments during a study on the effects of agricultural practices on the floodwater ecology of tropical rice fields. The most abundant species recorded in the ricefields were

Ian C. Simpson; Pierre A. Roger; Roberto Oficial; Ian F. Grant

1994-01-01

143

Copper: An alternative to mercury; more effective than zirconium in Kjeldahl digestion of ecological materials  

Microsoft Academic Search

Copper sulfate as a catalyst in Kjeldahl digestion of selected ecological materials has been demonstrated to be effective when a salt\\/acid ratio of 1 g\\/mL is used. Copper sulfate in combination with zirconium sulfate is no more effective than copper sulfate alone.

Martha N. Jones; H. David Bradshaw

1989-01-01

144

Predicting NonTarget Ecological Effects of Biological Control Agents: Evidence from Rhinocyllus conicus  

Microsoft Academic Search

The discovery and quantification of significant non-target ecological effects of Rhinocyllus conicus on native species in the northcentral USA provides the opportunity to experimentally evaluate factors that might help predict non-target host plant use, magni- tude of direct impact with transference, and indirect effects mediated by trophic interac- tions. The relevance for biocontrol risk assessment of at least four important

S. M. LOUDA; A. E. ARNETT

145

Accumulation of Deleterious Mutations in Small Abiotic Populations of RNA  

Microsoft Academic Search

The accumulation of slightly deleterious mutations in populations leads to the buildup of a genetic load and can cause the extinction of populations of small size. Mutation-accumulation experiments have been used to study this process in a wide variety of organisms, yet the exact mutational underpinnings of genetic loads and their fitness consequences remain poorly characterized. Here, we use an

Steven J. Soll; Carolina Diaz Arenas; Niles Lehman

2007-01-01

146

Epistasis between deleterious mutations and the evolution of recombination  

Microsoft Academic Search

Epistasis and the evolution of recombination are closely intertwined: epistasis generates linkage disequilibria (i.e. statistical associations between alleles), whereas recom- bination breaks them up. The mutational deterministic hypothesis (MDH) states that high recombination rates are maintained because the breaking up of linkage dis- equilibria generated by negative epistasis enables more efficient purging of deleterious mutations. However, recent theoretical and experimental

Roger D. Kouyos; Olin K. Silander; Sebastian Bonhoeffer

2007-01-01

147

Deleterious Mutation Accumulation and the Regeneration of Genetic Resources  

Microsoft Academic Search

The accumulation of mildly deleterious mutations accompanying recurrent regeneration of plant germ plasm was modeled under regeneration conditions characterized by different amounts of selection and genetic drift. Under some regeneration conditions (sample sizes >= 75 individuals and bulk harvesting of seed) mutation accumulation was negligible, but under others (sample sizes <75 individuals or equalization of seed production by individual plants)

Daniel J. Schoen; Jacques L. David; Thomas M. Bataillon

1998-01-01

148

Uses of ecologic studies in the assessment of intended treatment effects.  

PubMed

Because of the potential for confounding by indication (disease severity) in individual-level observational studies of intended treatment effects, a treatment designed to prevent an adverse event may appear to cause it. We use a hypothetical example to show that despite substantial variation in the frequency of treatment among patients residing in different geographic areas, a constant area-specific mortality rate can be observed, indicating the absence of confounding by indication at the ecologic level. The advantage of ecologic over individual-level observational studies in the assessment of intended treatment effects holds even if variations in disease severity, socioeconomic status, and other unmeasured factors are taken into account, as long as treatment utilization is influenced by practice style in the local medical community independently of disease severity. Ecologic studies can suggest the need for changes in practice, help resolve ethical issues, and indicate priorities for randomized trials. PMID:9973068

Wen, S W; Kramer, M S

1999-01-01

149

Sexual selection is ineffectual or inhibits the purging of deleterious mutations in Drosophila melanogaster.  

PubMed

The effects of sexual selection on population mean fitness are unclear and a subject of debate. Recent models propose that, because reproductive success may be condition dependent, much of the genome may be a target of sexual selection. Under this scenario, mutations that reduce health, and thus nonsexual fitness, may also be deleterious with respect to reproductive success, meaning that sexual selection may contribute to the purging of deleterious alleles. We tested this hypothesis directly by subjecting replicate Drosophila melanogaster populations to two treatments that altered the opportunity for sexual selection and then tracked changes in the frequency of six separate deleterious alleles with recessive and visible phenotypic effects. While natural selection acted to decrease the frequency of all six mutations, the addition of sexual selection did not aid in the purging of any of them, and for three of them appears to have hampered it. Courtship and mating have harmful effects in this species and mate choice assays showed that males directed more courtship and mating behavior toward wild-type over mutant females, providing a likely explanation for sexual selection's cost. Whether this cost extends to other mutations (e.g., those lacking visible phenotypic effects) is an important topic for future research. PMID:22759290

Arbuthnott, Devin; Rundle, Howard D

2012-02-26

150

Atorvastatin protects against deleterious cardiovascular consequences induced by chronic intermittent hypoxia.  

PubMed

Chronic intermittent hypoxia (IH), a major component of obstructive sleep apnea (OSA), contributes to the high risk of cardiovascular morbidity. We have previously demonstrated that IH-induced oxidative stress is involved in the hypertension and in the hypersensitivity to myocardial infarction. However, the mechanisms underlying these cardiovascular alterations are still unclear, as well as the role of potential protective treatment. Atorvastatin has pleiotropic actions, including increasing nitric oxide (NO) bioavailability and reducing inflammation and oxidative damage. The aim of this study was to evaluate the beneficial effect of a two time course of this treatment against the deleterious cardiovascular consequences of IH. Rats were divided into two groups subjected to chronic IH or normoxic (N) exposure. IH consisted of repetitive one-minute cycles (with only 30 s of a 5% inspired O2 fraction) and was applied for eight hours during daytime, for 14 (simultaneous protocol) or 28 d (delayed protocol). Atorvastatin (10 mg/kg/ d) or its vehicle was administered during the 14 d simultaneous protocol or the last 14 d of the delayed protocol. For both protocols, systolic arterial pressure was significantly increased by 14 d IH exposure. Atorvastatin prevented this deleterious effect in the simultaneous protocol. Carotid artery compliance and endothelial function were significantly altered after 28 d but not after 14 d of IH exposure. Delayed atorvastatin administration preserved these vascular parameters. IH also increased hypersensitivity to myocardial infarction after 14 d exposure, and atorvastatin abolished this deleterious effect. IH also enhanced cardiac NADPH expression and decreased aortic superoxide dismutase activity after 14 d exposure. Atorvastatin significantly restored these activities. In conclusion, whereas IH rapidly increased blood pressure, myocardial infarction hypersensitivity and oxidative stress, compliance, endothelial function and the structural wall of the carotid artery were only altered after a longer IH exposure. Atorvastatin prevented all these deleterious cardiovascular effects, leading to a potentially novel pharmacological therapeutic strategy for OSA syndrome. PMID:23404941

Totoson, Perle; Fhayli, Wassim; Faury, Gilles; Korichneva, Irina; Cachot, Sandrine; Baldazza, Marie; Ribuot, Christophe; Pépin, Jean-Louis; Lévy, Patrick; Joyeux-Faure, Marie

2013-02-12

151

Ecological effects of seaweed harvesting in the Gulf of California and Pacific Ocean off Baja California and California  

Microsoft Academic Search

The ecological effects of harvesting were investigated for two species, the giant kelp Macrocystis pyrifera and Eucheuma uncinatum, by using harvest records and aerial surveys that show yield changes and by using studies of recruitment, survivorship and community interactions. There were no ecological effects found for M. pyrifera harvested with contemporary methods, and there are no recommendations for changing current

D. C. Barilotti; J. A. Zertuche-González

1990-01-01

152

A microcosm approach for evaluating the effects of the fungicides benomyl and captan on soil ecological processes and plant growth  

Microsoft Academic Search

The effects of benomyl and captan on soil ecological processes were tested in integrated terrestrial microcosms containing agricultural soil, organic amendments and wheat seedlings. The effects of the two fungicides on important soil ecological processes were evaluated by measuring soil microbial activity and biomass, including soil substrate-induced respiration (SIR), soil enzyme activity (dehydrogenase, urease and acid phosphatase) and microbial biomass

Shu-Kang Chen; Clive A. Edwards; Scott Subler

2001-01-01

153

The Ecological Significance of Arbuscular Mycorrhizal Fungal Effects on Clonal Reproduction in Plants  

Microsoft Academic Search

The population ecology of clonal plants depends on the number and distri- bution of ramets formed during growth. Variation in clonal reproduction has previously been explained by variation in effects of abiotic resource heterogeneity and by plant ge- notypic variation. Different co-occurring species of the mutualistic arbuscular mycorrhizal fungi (AMF) have been shown to differentially alter growth traits of Prunella

R. Streitwolf-Engel; M. G. A. van der Heijden; A. Wiemken; I. R. Sanders

2001-01-01

154

Impact: Toward a Framework for Understanding the Ecological Effects of Invaders  

Microsoft Academic Search

Although ecologists commonly talk about the impacts of nonindigenous species, little formal attention has been given to defining what we mean by impact, or connecting ecological theory with particular measures of impact. The resulting lack of generalizations regarding invasion impacts is more than an academic problem; we need to be able to distinguish invaders with minor effects from those with

I. M. Parker; D. Simberloff; W. M. Lonsdale; K. Goodell; M. Wonham; P. M. Kareiva; M. H. Williamson; B. Von Holle; P. B. Moyle; J. E. Byers; L. Goldwasser

1999-01-01

155

Comparison of ecological effects and costs of communal waste management systems  

Microsoft Academic Search

The selection of an appropriate “optimal” recycling alternative has to take into consideration both the ecological and economic effects of the entire life-cycle. The aim of this paper is to compare different waste management systems by means of a life-cycle assessment (LCA) and a cost comparison. The analysis uses data regarding the amount of household waste generated, collected and treated

Peter Beigl; Stefan Salhofer

2004-01-01

156

Effects of nitrogen fertilizer and pesticide management on floodwater ecology in a wetland ricefield  

Microsoft Academic Search

This paper is the first in a series reporting a study on the effects of N fertilizer, green manure, and pesticide applications on the floodwater ecology of a tropical ricefield. Algal, zooplankton, and mollusc populations were monitored during a crop cycle in plots subjected to various methods of N management and different pesticide regimes. This paper presents the experimental design,

Ian C. Simpson; Pierre A. Roger; Roberto Oficial; Ian F. Grant

1994-01-01

157

Community-Based Eco-Education: Sound Ecology and Effective Education.  

ERIC Educational Resources Information Center

Reports on the development of a college-level eco-educational course that attempts to capitalize on the ecological and educational strengths of ecotourism by establishing a partnership with a local community. Makes suggestions for establishing community partnerships for effective international eco-educational program development. (Contains 15…

Niesenbaum, Richard A.; Gorka, Barbara

2001-01-01

158

Effects of Feed Additives and Mixed Eimeria Species Infection on Intestinal Microbial Ecology of Broilers1  

Microsoft Academic Search

Evaluation of digestive microbial ecology is necessary to understand effects of growth-promoting feed. In the current study, the dynamics of intestinal mi- crobial communities (MC) were examined in broilers fed diets supplemented with a combination of antibiotic (bac- itracin methylene disalicylate) and ionophore (Coban 60), and diets containing 1 of 2 essential oil (EO) blends, Crina Poultry (CP) and Crina

M. E. Hume; S. Clemente-Hernandez; E. O. Oviedo-Rondon

159

Regional Effects of Secondary Ecological Migration in Pasturing Area: A Case of Fuhai County in Xinjiang  

Microsoft Academic Search

Under the integrated influences of global climate changes and overgrazing, China rangeland has degraded over recent years. Fuhai County is located in the north margin of Junggar basin and its range land has experienced expansive degradation. The eco-migration policy are launched respectively by local government in 1998 and 2006. In order to analyze the regional effects of ecological migration, we

Changlong Sun; Jia Liu; Xiaolei Zhang; Hongru Du; Wenwen Ma

2009-01-01

160

Ecological, behavioral, and curricular interventions to prevent student problem behavior: An approach to implementing effective practices  

Microsoft Academic Search

While classroom management has been a highly researched topic in Applied Behavior Analysis, there are few empirically validated methods to effectively disseminate classroom techniques into school settings. There are three main classroom management areas that exist in the literature. These are: a) ecological factors, b) behavior principles, and c) curricular modifications. These three areas have been researched independently and in

Lindsey M Merritt

2010-01-01

161

Ecological energetics of the desert tortoise (Gopherus Agassizii): Effects of rainfall and drought  

Microsoft Academic Search

To elucidate ecological effects of variation in the temporal distribution of a limiting resource (water in the Mojave Desert), energetics of two free-living populations of desert tortoises (Gopherus [=Xerobates] agassizii) were studied concurrently over 18 mo with use of doubly-labeled water. Field metabolic rates (FMR) and feeding rates were highly variable. This variability was manifested at several levels, including seasonal

Cc Peterson

1996-01-01

162

Studying Pretrial Publicity Effects: New Methods for Improving Ecological Validity and Testing External Validity  

Microsoft Academic Search

Although research examining the effects of pretrial publicity (PTP) on individuals' appraisals of a defendant and verdict decision making generally has been found to be internally valid, the external validity has been questioned by some social scientists as well as lawyers and judges. It is often proposed that the verisimilitude (or ecological validity) of the research should be increased in

Christina A. Studebaker; Jennifer K. Robbennolt; Steven D. Penrod; Maithilee K. Pathak-Sharma; Jennifer L. Groscup; Jennifer L. Devenport

2002-01-01

163

Fermented liquid feed and fermented grain to piglets effect on gastrointestinal ecology and growth performance  

Microsoft Academic Search

A study was carried out to determine the microbial and nutritional characteristics of dry feed, liquid feed containing fermented liquid cereal grain, and fermented liquid compound feed, and their effect on gastrointestinal ecology and growth performance of piglets. Three dietary treatments were designed: dry feed (DRY); fermented liquid cereal grain feed (FLG); and fermented liquid feed (FLF). The FLF was

N. Canibe; B. B. Jensen

2007-01-01

164

Ecological and toxicological effects of inorganic nitrogen pollution in aquatic ecosystems: A global assessment  

Microsoft Academic Search

We provide a global assessment, with detailed multi-scale data, of the ecological and toxicological effects generated by inorganic nitrogen pollution in aquatic ecosystems. Our synthesis of the published scientific literature shows three major environmental problems: (1) it can increase the concentration of hydrogen ions in freshwater ecosystems without much acid-neutralizing capacity, resulting in acidification of those systems; (2) it can

Julio A. Camargo; Álvaro Alonso

2006-01-01

165

INFLUENCE OF SIZE ON FATE AND ECOLOGICAL EFFECTS OF KEPONE IN PHYSICAL MODELS  

EPA Science Inventory

Three different sizes of marine microcosms were used to study the influence of two features of spatial scale on the chemical fate and ecological effects of the pesticide Kepone. ncreasing the size of microcosms reduced the ratio of wall surface area to volume of contained sea wat...

166

Community-Based Eco-Education: Sound Ecology and Effective Education.  

ERIC Educational Resources Information Center

|Reports on the development of a college-level eco-educational course that attempts to capitalize on the ecological and educational strengths of ecotourism by establishing a partnership with a local community. Makes suggestions for establishing community partnerships for effective international eco-educational program development. (Contains 15…

Niesenbaum, Richard A.; Gorka, Barbara

2001-01-01

167

Deleterious alleles and differential viability in progeny of natural hemiclonal frogs.  

PubMed

Abstract.-Spontaneous deleterious mutations are expected to accumulate through Muller's ratchet in clonally reproducing organisms and may lead to their extinction. We study deleterious mutations and their effects in a system of European frogs. Rana esculenta (RL), natural hybrids R. ridibunda (RR) X R. lessonae (LL), reproduce hemiclonally; both sexes exclude the L genome in the germ line and produce unrecombined R gametes; hybridity is restored each generation by matings of RL with coexisting LL. Different allozyme-defined hybrid hemiclones (R genome haplotypes) are thought to have originated independently from primary hybridizations RR x LL. Natural matings between two hybrids usually lead to inviable RR tadpoles. This inviability is thought to result from unmasked deleterious alleles on the clonally transmitted R genomes. Most simply it reflects homozygosity for recessive deleterious alleles at particular loci; alternatively (consistent with absence of RR adults in multiclonal populations) it may reflect hemiclone-specific sets of incompletely recessive deleterious mutations that cumulatively cause inviability when two such genomes are combined. If inviability results from the former, progeny of two hybrids of different hemiclones, whether allopatric or coexisting, should be viable, because it is improbable that their R genomes share recessive deleterious alleles at the same set of loci; if inviability results from the latter, progeny of hybrids of different hemiclones should be inviable, especially when hybrid lineages are old. We tested these hypotheses in artificial crosses, using frogs from three regions: hemiclonal hybrids outside R. ridibunda's range from northern Switzerland (two abundant coexisting allozyme-defined hemiclones; estimated lineage age < or = 5,000 generations) and from Sicily, Italy (one hemiclone; estimated age > or = 25,000 generations) and R. ridibunda from Poland. We generated RR progeny, which we reared under benign conditions in the laboratory, by crossing (1) two hybrids from the same region (H x H local); (2) two hybrids from different regions (H X H foreign); (3) hybrids and R. ridibunda (H X R); and (4) two R. ridibunda (R X R). Survival to metamorphosis was similar and high for R x R, H X H foreign, and H X R, whereas all tadpoles of H X H local died before metamorphosis. This supports the hypothesis that homozygosity for recessive deleterious mutations at particular loci causes inviability. Crosses within and between the two coexisting hemiclones from Switzerland were, however, equally inviable. This result may reflect episodic sexual recombination in RR progeny from exceptional successful interclonal hybrid X hybrid matings, followed by matings of such RR with LL. This process would both slow down or halt Muller's ratchet and disrupt genetic independence of coexisting hemiclones, so that the same remaining deleterious R alleles could exist in different allozyme-defined hemiclones. Whereas all data are consistent with the prediction of Muller's ratchet operating on clonally transmitted R genomes of natural hybrid lineages, they are insufficient to demonstrate such operation, because deleterious recessives that mutated after clone formation and those that preexisted in the R. ridibunda source populations that formed the hemiclonal lineages are not distinguished. The possibility of episodic sexual recombination must be carefully taken into account when studying Muller's ratchet in natural populations of this Rana system. PMID:12093017

Guex, Gaston-Denis; Hotz, Hansjurg; Semlitsch, Raymond D

2002-05-01

168

Ecological significance of residual exposures and effects from the Exxon Valdez oil spill.  

PubMed

An ecological significance framework is used to assess the ecological condition of Prince William Sound (PWS), Alaska, USA, in order to address the current management question: 17 y following the Exxon Valdez oil spill (EVOS), are there any remaining and continuing ecologically significant exposures or effects on the PWS ecosystem caused by EVOS? We examined the extensive scientific literature funded by the Exxon Valdez Trustees or by ExxonMobil to assess exposures and effects from EVOS. Criteria to assess ecological significance include whether a change in a valued ecosystem component (VEC) is sufficient to affect the structure, function, and/or health of the system and whether such a change exceeds natural variability. The EVOS occurred on 24 March 1989, releasing over 250,000 barrels of crude oil into PWS. Because PWS is highly dynamic, the residual oil was largely eliminated in the first few years, and now only widely dispersed, highly weathered, or isolated small pockets of residual contamination remain. Many other sources of polycyclic aromatic hydrocarbons (PAHs) exist in PWS from past or present human activities or natural oil seeps. Multiple-lines-of-evidence analyses indicate that residual PAHs from EVOS no longer represent an ecologically significant exposure risk to PWS. To assess the ecological significance of any residual effects from EVOS, we examined the literature on more than 20 VECs, including primary producers, filter feeders, fish and bird primary consumers, fish and bird top predators, a bird scavenger, mammalian primary consumers and top predators, biotic communities, ecosystem-level properties of trophodynamics and biogeochemical processes, and landscape-level properties of habitat mosaic and wilderness quality. None of these has any ecologically significant effects that are detectable at present, with the exception of 1 pod of orcas and possibly 1 subpopulation of sea otters; however, in both those cases, PWS-wide populations appear to have fully recovered. Many other stressors continue to affect PWS adversely, including climate and oceanographic variability, increased tourism and shipping, invasive species, the 1964 earthquake, and overexploitation of marine resources, with associated cascading effects on populations of PWS fish and predators. We conclude that the PWS ecosystem has now effectively recovered from EVOS. PMID:16869437

Harwell, Mark A; Gentile, John H

2006-07-01

169

Can deleterious mutations explain the time dependency of molecular rate estimates?  

PubMed

It has recently been observed by Ho et al. (Ho SYW, Phillips MJ, Cooper A, Drummond AJ. 2005. Time dependency of molecular rate estimates and systematic overestimation of recent divergence times. Mol Biol Evol. 22(7):1561-1568) that apparent rates of molecular evolution increase when measured over short timespans. I investigate whether the data are explainable purely by deleterious mutations. I derive an empirical approximation for the persistence of these mutations in a randomly mating population and, hence, derive lower limits on effective population sizes. These limits are high and get higher if additional reasonable assumptions are made. This casts doubt on whether deleterious mutations are able to explain the apparent rate acceleration. PMID:16959870

Woodhams, Michael

2006-09-07

170

Amino acid composition of proteins reduces deleterious impact of mutations.  

PubMed

The evolutionary origin of amino acid occurrence frequencies in proteins (composition) is not yet fully understood. We suggest that protein composition works alongside the genetic code to minimize impact of mutations on protein structure. First, we propose a novel method for estimating thermodynamic stability of proteins whose sequence is constrained to a fixed composition. Second, we quantify the average deleterious impact of substituting one amino acid with another. Natural proteome compositions are special in at least two ways: 1) Natural compositions do not generate more stable proteins than the average random composition, however, they result in proteins that are less susceptible to damage from mutations. 2) Natural proteome compositions that result in more stable proteins (i.e. those of thermophiles) are also tuned to have a higher tolerance for mutations. This is consistent with the observation that environmental factors selecting for more stable proteins also enhance the deleterious impact of mutations. PMID:24108121

Hormoz, Sahand

2013-10-10

171

Amino acid composition of proteins reduces deleterious impact of mutations  

NASA Astrophysics Data System (ADS)

The evolutionary origin of amino acid occurrence frequencies in proteins (composition) is not yet fully understood. We suggest that protein composition works alongside the genetic code to minimize impact of mutations on protein structure. First, we propose a novel method for estimating thermodynamic stability of proteins whose sequence is constrained to a fixed composition. Second, we quantify the average deleterious impact of substituting one amino acid with another. Natural proteome compositions are special in at least two ways: 1) Natural compositions do not generate more stable proteins than the average random composition, however, they result in proteins that are less susceptible to damage from mutations. 2) Natural proteome compositions that result in more stable proteins (i.e. those of thermophiles) are also tuned to have a higher tolerance for mutations. This is consistent with the observation that environmental factors selecting for more stable proteins also enhance the deleterious impact of mutations.

Hormoz, Sahand

2013-10-01

172

Amino acid composition of proteins reduces deleterious impact of mutations  

PubMed Central

The evolutionary origin of amino acid occurrence frequencies in proteins (composition) is not yet fully understood. We suggest that protein composition works alongside the genetic code to minimize impact of mutations on protein structure. First, we propose a novel method for estimating thermodynamic stability of proteins whose sequence is constrained to a fixed composition. Second, we quantify the average deleterious impact of substituting one amino acid with another. Natural proteome compositions are special in at least two ways: 1) Natural compositions do not generate more stable proteins than the average random composition, however, they result in proteins that are less susceptible to damage from mutations. 2) Natural proteome compositions that result in more stable proteins (i.e. those of thermophiles) are also tuned to have a higher tolerance for mutations. This is consistent with the observation that environmental factors selecting for more stable proteins also enhance the deleterious impact of mutations.

Hormoz, Sahand

2013-01-01

173

Contrasted effects of diversity and immigration on ecological insurance in marine bacterioplankton communities.  

PubMed

The ecological insurance hypothesis predicts a positive effect of species richness on ecosystem functioning in a variable environment. This effect stems from temporal and spatial complementarity among species within metacommunities coupled with optimal levels of dispersal. Despite its importance in the context of global change by human activities, empirical evidence for ecological insurance remains scarce and controversial. Here we use natural aquatic bacterial communities to explore some of the predictions of the spatial and temporal aspects of the ecological insurance hypothesis. Addressing ecological insurance with bacterioplankton is of strong relevance given their central role in fundamental ecosystem processes. Our experimental set up consisted of water and bacterioplankton communities from two contrasting coastal lagoons. In order to mimic environmental fluctuations, the bacterioplankton community from one lagoon was successively transferred between tanks containing water from each of the two lagoons. We manipulated initial bacterial diversity for experimental communities and immigration during the experiment. We found that the abundance and production of bacterioplankton communities was higher and more stable (lower temporal variance) for treatments with high initial bacterial diversity. Immigration was only marginally beneficial to bacterial communities, probably because microbial communities operate at different time scales compared to the frequency of perturbation selected in this study, and of their intrinsic high physiologic plasticity. Such local "physiological insurance" may have a strong significance for the maintenance of bacterial abundance and production in the face of environmental perturbations. PMID:22701572

Bouvier, Thierry; Venail, Patrick; Pommier, Thomas; Bouvier, Corinne; Barbera, Claire; Mouquet, Nicolas

2012-06-12

174

The ecological effectiveness of protected areas: The United Kingdom  

Microsoft Academic Search

Given the importance placed on protected areas, determining their effectiveness in representing and maintaining biodiversity is a core issue in conservation biology. Nonetheless, frameworks identifying the breadth of issues associated with this effectiveness, and case studies of how well these are understood in particular regions, remain lacking. In this paper, we provide such a framework and an overview of the

Kevin J. Gaston; Kevin Charman; Sarah F. Jackson; Paul R. Armsworth; Aletta Bonn; Robert A. Briers; Claire S. Q. Callaghan; Roger Catchpole; John Hopkins; William E. Kunin; Jim Latham; Paul Opdam; Rob Stoneman; David A. Stroud; Ros Tratt

2006-01-01

175

Ecological effects, transport, and fate of mercury: a general review  

Microsoft Academic Search

Mercury at low concentrations represents a major hazard to microorganisms. Inorganic mercury has been reported to produce harmful effects at 5 ?g\\/l in a culture medium. Organomercury compounds can exert the same effect at concentrations 10 times lower than this. The organic forms of mercury are generally more toxic to aquatic organisms and birds than the inorganic forms. Aquatic plants

Dean W. Boening

2000-01-01

176

Effects of plants containing secondary compounds and plant oils on rumen fermentation and ecology  

Microsoft Academic Search

A number of experiments have been conducted to investigate effects of tropical plants containing condensed tannins and\\/or\\u000a saponins present in tropical plants and some plant oils on rumen fermentation and ecology in ruminants. Based on both in vitro\\u000a and in vivo trials, the results revealed important effects on rumen microorganisms and fermentation including methane production.\\u000a Incorporation and\\/or supplementation of these

Metha Wanapat; Pongthon Kongmun; Onanong Poungchompu; Anusorn Cherdthong; Pichad Khejornsart; Ruangyote Pilajun; Sujittra Kaenpakdee

177

The Cummulative Ecological Effects of Normal Offshore Petroleum Operations Contrasted With Those Resulting From Continental Shelf Oil Spills  

Microsoft Academic Search

Assessments of the cumulative ecological effects of chronic sublethal discharges from normal (non-spill) offshore petroleum operations have been based on (1) model studies, (2) controlled laboratory and microcosm experiments, (3) studies of spills of crude oil and its refined products and of severe organic pollution, and (4) ecological field studies in areas of intensive petroleum operations. Methods (2) and (3)

J. M. Sharp; S. G. Appan

1982-01-01

178

Environmental and Ontogenetic Effects on Intraspecific Trait Variation of a Macrophyte Species across Five Ecological Scales  

PubMed Central

Although functional trait variability is increasingly used in community ecology, the scale- and size-dependent aspects of trait variation are usually disregarded. Here we quantified the spatial structure of shoot height, branch length, root/shoot ratio and leaf number in a macrophyte species Potamogeton maackianus, and then disentangled the environmental and ontogenetic effects on these traits. Using a hierarchical nested design, we measured the four traits from 681 individuals across five ecological scales: lake, transect, depth stratus, quadrat and individual. A notable high trait variation (coefficient variation: 48–112%) was observed within species. These traits differed in the spatial structure, depending on environmental factors of different scales. Shoot height and branch length were most responsive to lake, transect and depth stratus scales, while root/shoot ratio and leaf number to quadrat and individual scales. The trait variations caused by environment are nearly three times higher than that caused by ontogeny, with ontogenetic variance ranging from 21% (leaf number) to 33% (branch length) of total variance. Remarkably, these traits showed non-negligible ontogenetic variation (0–60%) in each ecological scale, and significant shifts in allometric trajectories at lake and depth stratus scales. Our results highlight that environmental filtering processes can sort individuals within species with traits values adaptive to environmental changes and ontogenetic variation of functional traits was non-negligible across the five ecological scales.

Zhong, Jiayou; Cao, Te; Ni, Leyi; Xie, Ping

2013-01-01

179

Maternal effects and evolution at ecological time-scales  

Microsoft Academic Search

Summary 1. Genetic and environmental maternal effects can play an important role in the evo- lutionary dynamics of a population: they may have a substantial impact on the rate and direction of genetic change in response to selection, and they may generate immediate phenotypic change via phenotypic plasticity. Because of this potential to generate rapid phenotypic change in a population,

K. RÄSÄNEN; L. E. B. KRUUK

2007-01-01

180

Creating riverine wetlands: Ecological succession, nutrient retention, and pulsing effects  

Microsoft Academic Search

Successional patterns, water quality changes, and effects of hydrologic pulsing are documented for a whole-ecosystem experiment involving two created wetlands that have been subjected to continuous inflow of pumped river water for more than 10 years. At the beginning of the growing season in the first year of the experiment (1994), 2400 individuals representing 13 macrophyte species were introduced to

William J. Mitsch; Li Zhang; Christopher J. Anderson; Anne E. Altor; Maria E. Hernández

2005-01-01

181

ECOLOGICAL EFFECTS OF EXPERIMENTAL ACIDIFICATION ON A STREAM ECOSYSTEM  

EPA Science Inventory

The report describes the quantitative effects of experimentally increasing the acidity of a mountain stream ecosystem to pH levels frequently found in incident precipitation in the northeastern United States. The field experiment was designed to test the hypothesis that such acid...

182

DESIGN CRITERIA FOR A PREDICTIVE ECOLOGICAL EFFECTS MODELING SYSTEM  

EPA Science Inventory

The capability to predict the environmental fate of chemicals based on their chemical properties is well developed and widely practiced. Poorly developed, however is the capability to predict the effects of those chemicals. To address the deficiency, significant effort has been d...

183

EFFECT OF DIFFERENT POLLUTANTS ON ECOLOGICALLY IMPORTANT POLYCHAETE WORMS  

EPA Science Inventory

The procedures for culturing marine polychaetous annelids from egg to egg under laboratory conditions were described. A manual was prepared detailing the procedures used in culturing 12 species of polychaetes. The effects of heavy metals and the water soluble fractions of petrole...

184

ECOLOGICAL EXPOSURE AND EFFECTS OF AIRBORNE TOXIC CHEMICALS: AN OVERVIEW  

EPA Science Inventory

Since the release of the Environmental Protection Agency's (EPA's) toxic release inventory (TRI) estimates for 1987, there has been a heightened concern over the nation's air quality. rimarily, this concern has been directed at human health effects in industrial-urban areas. he f...

185

Fire Ecology  

NSDL National Science Digital Library

Forest fires have become a regular summertime occurrence in North America, sparking debate about the proper role of fire on the land. The following websites examine fires and fire ecology in different ecosystems, regions, and time periods. The first site (1), from the USGS-Western Ecological Research Center shares information about fire ecology research in the California shrublands, Sierra Nevada forests, and Mohave and Sonoran deserts. The second site (2) features the Fire Ecology Center at Texas Tech University. The Fire Ecology Center focuses on the role of fire in grassland ecosystems and their website contains information on current research, publications, managing pastures, managing problem plants, and more. The third site (3), from the USGS-Northern Prairie Wildlife Research Center contains "an annotated bibliography on fire in North American wetland ecosystems and a subject index of all fire-related literature that has appeared in Wildlife Review." Hosted by Yellowstone National Park, the fourth site (4) addresses wildland fires in Yellowstone. The Park website presents brief sections on Fire Ecology, Fire Monitoring, Prescribed Fire, and Fire Effects -- to name a few. The fifth (5) site, from the Canadian Forest Service, provides information about forest fires in Canada including weekly fire statistics, fire research, daily fire maps, a fire database, and more. Part of a great site on the land use history of the Colorado Plateau from Northern Arizona University, the sixth site (6) offers a brief overview of wildfire history and ecology on the Plateau with links to information about ponderosa pine fire ecology, reintroduction of fire to forest ecosystems, and fire ecology research studies. The seventh site (7), from DiscoverySchool.com, contains a lesson plan on forest fire ecology for grade levels 9-12. The lesson spans two class periods and the site provides objectives, materials needed, discussion questions, academic standards, and more. The final (8) website, from the Why Files, "examines the role of fire in natural systems, and the role of science in understanding wildfires." The eleven-page website follows a kid-friendly narrative format and includes a bibliography and glossary.

186

The charcoal effect in Boreal forests: mechanisms and ecological consequences  

Microsoft Academic Search

Wildfire is the principal disturbance regime in northern Boreal forests, where it has important rejuvenating effects on soil\\u000a properties and encourages tree seedling regeneration and growth. One possible agent of this rejuvenation is fire-produced\\u000a charcoal, which adsorbs secondary metabolites such as humus phenolics produced by ericaceous vegetation in the absence of\\u000a fire, which retard nutrient cycling and tree seedling growth.

D. A. Wardle; O. Zackrisson; M.-C. Nilsson

1998-01-01

187

Use of QSARs in international decision-making frameworks to predict ecologic effects and environmental fate of chemical substances.  

PubMed Central

This article is a review of the use, by regulatory agencies and authorities, of quantitative structure-activity relationships (QSARs) to predict ecologic effects and environmental fate of chemicals. For many years, the U.S. Environmental Protection Agency has been the most prominent regulatory agency using QSARs to predict the ecologic effects and environmental fate of chemicals. However, as increasing numbers of standard QSAR methods are developed and validated to predict ecologic effects and environmental fate of chemicals, it is anticipated that more regulatory agencies and authorities will find them to be acceptable alternatives to chemical testing.

Cronin, Mark T D; Walker, John D; Jaworska, Joanna S; Comber, Michael H I; Watts, Christopher D; Worth, Andrew P

2003-01-01

188

A Review of STD\\/HIV Preventive Interventions for Adolescents: Sustaining Effects Using an Ecological Approach  

Microsoft Academic Search

Objective Behavioral intervention programs to reduce adolescent sexual risk behaviors have shown statistically significant reductions in the short-term; however, longer-term follow-up has demonstrated that effects diminish. One criticism has been the reliance on individual-level models. We review the research that has shaped this narrow perspective and propose that a broader, ecological perspective is needed to amplify and extend the efficacy

Ralph J. DiClemente; Laura F. Salazar; Richard A. Crosby

2007-01-01

189

Effects of systematic exposure assessment errors in partially ecologic case-control studies  

Microsoft Academic Search

Background In ecologic studies, group-level rather than individual-level exposure data are used. When using group-level exposure data, established by sufficiently large samples of individual exposure assessments, the bias of the effect estimate due to sampling errors or random assessment errors at the individual-level is generally negligible. In contrast, systematic assessment errors may produce more pronounced errors in the group-level exposure

Jonas Björk; Ulf Strömberg

2002-01-01

190

Effects of inter-pond distance on the breeding ecology of tungara frogs  

Microsoft Academic Search

Habitat and resource distributions can influence the movement and aggregation of individuals and thus have important effects\\u000a on breeding behavior and ecology. Though amphibians have been model systems for the study of breeding behavior and sexual\\u000a selection, most studies have examined breeding behavior within a single pond. As a result, little is known about how inter-pond\\u000a distance affects breeding amphibians.

David M. Marsh; A. Stanley Rand; Michael J. Ryan

2000-01-01

191

Effect of ecological factors on the inhibitory spectrum and activity of bacteriocins  

Microsoft Academic Search

The effect of food components and ecological factors on the activities of nisin, sakacin P and curvacin A was evaluated. Lactobacillus curvatus, Listeria innocua, Salmonella and Escherichia coli including E. coli O157:H7 were used as target organisms. Lecithin, casein, and divalent cations were antagonists of the bacteriocins at 0.1%, 0.1% and 10 mmol l?1, respectively. A decrease in pH as

Michael G Gänzle; Sigrid Weber; Walter P Hammes

1999-01-01

192

Effects of Partially Anadromous Arctic Charr ( Salvelinus alpinus ) Populations on Ecology of Coastal Arctic Lakes  

Microsoft Academic Search

Little research has been conducted on effects of iteroparous anadromous fishes on Arctic lakes. We investigated trophic ecology,\\u000a fish growth, and food web structure in six lakes located in Nunavut, Canada; three lakes contained anadromous Arctic charr\\u000a (Salvelinus alpinus) whereas three lakes did not contain Arctic charr. All lakes contained forage fishes and lake trout (Salvelinus namaycush; top predator). Isotope

Heidi K. Swanson; Karen A. Kidd; James D. Reist

2010-01-01

193

Evaluating the effects of embodied energy in international trade on ecological footprint in China  

Microsoft Academic Search

Based on sub-sectoral level of economy and detailed traded items, embodied energy (EE) in international trade flow in China is estimated during 1996–2004, and the effects of EE on sustainability are quantified by using one of the most popular indicators—Ecological footprint (EF). A framework of EF method, which is more relevant to realism of specific country, is proposed in this

Li Hong; Zhang Pei Dong; He Chunyu; Wang Gang

2007-01-01

194

Community metabolism of aquatic Closed Ecological Systems: Effects of nitrogen sources  

Microsoft Academic Search

To investigate the effect of nitrogen sources on Closed Ecological Systems (CESs), three nitrogen sources (NaNO3, sodium nitrate; NH4Cl, ammonium chloride; and NH4NO3, ammonium nitrate) were each tested in freshwater CESs consisting of a chemically defined medium, three species of green algae (Ankistrodesmus, Scenedesmus, and Selenastrum), the grazer Daphnia magna, and associated microbes, under 12 h light\\/12 h dark cycles.

Frieda B. Taub

2009-01-01

195

Community metabolism of aquatic Closed Ecological Systems: Effects of nitrogen sources  

Microsoft Academic Search

To investigate the effect of nitrogen sources on Closed Ecological Systems (CESs), three nitrogen sources (NaNO3, sodium nitrate; NH4Cl, ammonium chloride; and NH4NO3, ammonium nitrate) were each tested in freshwater CESs consisting of a chemically defined medium, three species of green algae (Ankistrodesmus, Scenedesmus, and Selenastrum), the grazer Daphnia magna, and associated microbes, under 12h light\\/12h dark cycles. It had

Frieda B. Taub

2009-01-01

196

Water cycles in closed ecological systems: effects of atmospheric pressure.  

PubMed

In bioregenerative life support systems that use plants to generate food and oxygen, the largest mass flux between the plants and their surrounding environment will be water. This water cycle is a consequence of the continuous change of state (evaporation-condensation) from liquid to gas through the process of transpiration and the need to transfer heat (cool) and dehumidify the plant growth chamber. Evapotranspiration rates for full plant canopies can range from ~1 to 10 L m-2 d-1 (~1 to 10 mm m-2 d-1), with the rates depending primarily on the vapor pressure deficit (VPD) between the leaves and the air inside the plant growth chamber. VPD in turn is dependent on the air temperature, leaf temperature, and current value of relative humidity (RH). Concepts for developing closed plant growth systems, such as greenhouses for Mars, have been discussed for many years and the feasibility of such systems will depend on the overall system costs and reliability. One approach for reducing system costs would be to reduce the operating pressure within the greenhouse to reduce structural mass and gas leakage. But managing plant growth environments at low pressures (e.g., controlling humidity and heat exchange) may be difficult, and the effects of low-pressure environments on plant growth and system water cycling need further study. We present experimental evidence to show that water saturation pressures in air under isothermal conditions are only slightly affected by total pressure, but the overall water flux from evaporating surfaces can increase as pressure decreases. Mathematical models describing these observations are presented, along with discussion of the importance for considering "water cycles" in closed bioregenerative life support systems. PMID:12481804

Rygalov, Vadim Y; Fowler, Philip A; Metz, Joannah M; Wheeler, Raymond M; Bucklin, Ray A

2002-01-01

197

Incorporating uncertainity in regional ecological risk assessments: Ozone effects on southeastern USA forests  

SciTech Connect

Currently, assessments of how environmental stresses such as tropospheric ozone affect forests employ point estimates of factors such as ozone dose and species sensitivity. However, there is substantial regional heterogeneity in such factors. Hence, we have developed an approach for incorporating probabilistic analysis in estimating ecological risk at a regional scale. As an example, we model the effects of tropospheric ozone on the growth of loblolly pine stands in the southeastern USA. Our approach links software capable of automated Monte Carlo simulation to a Geographic Information System in order to assess the influence of uncertainty in factors such as ozone dose, soil moisture availability, and climate on regional patterns of loblolly growth rate. We demonstrate that this methodology may improve assessments of ecological risk by quantitating regional patterns in the influence of various factors on the predicted response of forests to ozone as well as identifying regions in which uncertainty in model predictions is the greatest.

Woodbury, P.B.; Smith, J.E.; Weinstein, D.A. [Boyce Thompson Institute for Plant Research, Ithaca, NY (United States)] [and others

1995-09-01

198

Potential Ecological and Nontarget Effects of Transgenic Plant Gene Products on Agriculture, Silviculture, and Natural Ecosystems: General Introduction.  

National Technical Information Service (NTIS)

A symposium was held at the Univ. of Maryland Nov. 30 - Dec. 2, 1992, to discuss transgenic plant risk assessment issues for measurement and identification of potential ecological and nontarget organism effects. The goal was to identify available scientif...

R. J. Seidler M. Levin

1994-01-01

199

Toward a Sustainable Future: Addressing the Long-Term Effects of Motor Vehicle Transportation on Climate and Ecology.  

National Technical Information Service (NTIS)

Contents: Executive Summary; Sustainability and Transportation; Trends and Outlook in Motor Vehicle Transportation; Carbon Dioxide Buildup and Motor Vehicle Transportation; Cumulative Ecological Effects of Vehicle Emissions and Infrastructure; Summary Ass...

1997-01-01

200

EVALUATION OF METHODS FOR DETECTING ECOLOGICAL EFFECTS FROM GENETICALLY ENGINEERED MICROORGANISMS AND PEST CONTROL AGENTS IN TERRESTRIAL SYSTEMS  

EPA Science Inventory

This report summarizes and evaluates research from several laboratories that deals with the detection of ecological effects induced through exposure of microbes or plants to genetically engineered microorganisms (GEMS) and microbial pest control agents (MPCAS) . The development o...

201

Effects of Increasing Urbanization on the Ecological Integrity of Open Space Preserves  

NASA Astrophysics Data System (ADS)

This article analyzes the effects of increasing urbanization on open space preserves within the metropolitan area of Phoenix, Arizona, USA. Time series analysis is used in 10-year increments over 40 years to study urban landscape change. Three landscape metrics—(1) matrix utility (measures intensity of adjacent land uses), (2) isolation (measures distances to other open space patches), and (3) connectivity (measures physical links to other open space patches and corridors)—are used to assess changes in landscape patterns and serve as indicators of urban ecological integrity of the open space preserves. Results show that in the case of both open space preserves, general decline in indicators of urban ecological integrity was evident. The matrix utility analysis demonstrated that increasing intensity of land uses adjacent to preserve is likely to increase edge effects, reducing the habitat value of interior or core habitat areas. Isolation analysis showed that both preserves have experienced increasing isolation from other open space elements over time. Also, connectivity analysis indicated that terrestrial connections to other open space elements have also deteriorated. Conclusions of this research demonstrate that while preservation of natural areas as open space is important in an urban context, intense development of surrounding areas reduces the urban ecological integrity significantly.

Esbah, Hayriye; Cook, Edward A.; Ewan, Joseph

2009-05-01

202

Deleterious effect of nitric oxide inhibition in chronic hepatopulmonary syndrome.  

PubMed

On the basis of limited experimental and clinical studies, increased activity of the vasodilatory nitric oxide-cyclic guanosine monophosphate pathway is considered to play a key role in the pathogenesis of hepatopulmonary syndrome. We report a 46-year-old woman with Child-Pugh class C cirrhosis and progressive dyspnoea for 12 months. Investigations revealed elevated circulating concentrations of nitric oxide metabolites and exhaled nitric oxide levels, an hyperdynamic circulation with low systemic vascular resistance and mean arterial pressure, a large right to left intrapulmonary shunt fraction on radiolabelled macroaggregated albumin perfusion scanning, positive contrast-enhanced echocardiography, reduced diffusion capacity of carbon monoxide, hypoxaemia and orthodeoxyia, all in keeping with severe hepatopulmonary syndrome. Sequential inhibition of the nitric oxide-cyclic guanosine monophosphate pathway using curcumin (diferuloylmethane), terlipressin and methylene blue was associated with substantial improvements in vascular tone and the hyperdynamic circulation. No improvement, however, in the intrapulmonary shunt was demonstrated. Both hypoxaemia and orthodeoxia were substantially, reproducibly and reversibly worsened with all three treatments. Our findings argue against the contention that intrapulmonary shunting and impairment in arterial oxygenation in hepatopulmonary syndrome are necessarily the consequence of on-going, nitric oxide-cyclic guanosine monophosphate-mediated vasodilatation, at least in the chronic stage, and, given the possibility of substantial worsening of pulmonary oxygen exchange, suggest that inhibition of the nitric oxide-cyclic guanosine monophosphate pathway should be avoided in this setting. PMID:17353701

Almeida, John A; Riordan, Stephen M; Liu, Jia; Galhenage, Sumedha; Kim, Robert; Bihari, David; Wegner, Eva A; Cranney, Gregory B; Thomas, Paul S

2007-04-01

203

Life history plasticity magnifies the ecological effects of a social wasp invasion  

PubMed Central

An unresolved question in ecology concerns why the ecological effects of invasions vary in magnitude. Many introduced species fail to interact strongly with the recipient biota, whereas others profoundly disrupt the ecosystems they invade through predation, competition, and other mechanisms. In the context of ecological impacts, research on biological invasions seldom considers phenotypic or microevolutionary changes that occur following introduction. Here, we show how plasticity in key life history traits (colony size and longevity), together with omnivory, magnifies the predatory impacts of an invasive social wasp (Vespula pensylvanica) on a largely endemic arthropod fauna in Hawaii. Using a combination of molecular, experimental, and behavioral approaches, we demonstrate (i) that yellowjackets consume an astonishing diversity of arthropod resources and depress prey populations in invaded Hawaiian ecosystems and (ii) that their impact as predators in this region increases when they shift from small annual colonies to large perennial colonies. Such trait plasticity may influence invasion success and the degree of disruption that invaded ecosystems experience. Moreover, postintroduction phenotypic changes may help invaders to compensate for reductions in adaptive potential resulting from founder events and small population sizes. The dynamic nature of biological invasions necessitates a more quantitative understanding of how postintroduction changes in invader traits affect invasion processes.

Wilson, Erin E.; Mullen, Lynne M.; Holway, David A.

2009-01-01

204

Environmental monitoring and ecological risk assessment for pesticide contamination and effects in Lake Pamvotis, northwestern Greece.  

PubMed

Monitoring of pesticide residues in water and sediments was conducted as a basis for subsequent ecotoxicological risk assessment for the shallow eutrophic Lake Pamvotis, northwestern Greece. During a one-year study period, atrazine, desethylatrazine (DEA), simazine, diazinon, malathion, oxamyl, carbofuran, and ethion were detected in water and atrazine, desethylatrazine, diazinon, and s-ethyl dipropylthiocarbamate (EPTC) in sediments, all at ppb concentration level. Temporal variation in pesticide concentrations was observed. Highest residue levels for most pesticides in both water and sediment matrices occurred in the May to July period with the exception of atrazine and DEA, which show highest levels in water during the September to November period. The ecological risk associated with pesticide contamination was assessed using two different methods: The toxic unit method, which provides a first indication of the relative contribution of detected pesticides to the total toxicity and a probabilistic approach, and the inverse method of Van Straalen and Denneman, which is used to quantify the ecological risk. The maximum percentage of the ecological risk was 10.3 and 51.8% for water and 17.2 and 70.6% for sediment, based on acute and chronic level, respectively. These results show that pesticides exert a significant pressure on the aquatic system of Lake Pamvotis, especially for the chronic-effect level. Simple quotient methods should be coupled with higher-tier risk assessment, especially if restoration activities on lake ecosystems are to be undertaken for sustainable development. PMID:16117136

Hela, Dimitra G; Lambropoulou, Dimitra A; Konstantinou, Ioannis K; Albanis, Triantafyllos A

2005-06-01

205

Administrative Ecology  

ERIC Educational Resources Information Center

|This article discusses how all four facets of administrative ecology help dispel the claims about the "impossibility" of the superintendency. These are personal ecology, professional ecology, organizational ecology, and community ecology. Using today's superintendency as an administrative platform, current literature describes a preponderance of…

McGarity, Augustus C., III; Maulding, Wanda

2007-01-01

206

Diversity, decoys and the dilution effect: how ecological communities affect disease risk.  

PubMed

Growing interest in ecology has recently focused on the hypothesis that community diversity can mediate infection levels and disease ('dilution effect'). In turn, biodiversity loss--a widespread consequence of environmental change--can indirectly promote increases in disease, including those of medical and veterinary importance. While this work has focused primarily on correlational studies involving vector-borne microparasite diseases (e.g. Lyme disease, West Nile virus), we argue that parasites with complex life cycles (e.g. helminths, protists, myxosporeans and many fungi) offer an excellent additional model in which to experimentally address mechanistic questions underlying the dilution effect. Here, we unite recent ecological research on the dilution effect in microparasites with decades of parasitological research on the decoy effect in macroparasites to explore key questions surrounding the relationship between community structure and disease. We find consistent evidence that community diversity significantly alters parasite transmission and pathology under laboratory as well as natural conditions. Empirical examples and simple transmission models highlight the diversity of mechanisms through which such changes occur, typically involving predators, parasite decoys, low competency hosts or other parasites. However, the degree of transmission reduction varies among diluting species, parasite stage, and across spatial scales, challenging efforts to make quantitative, taxon-specific predictions about disease. Taken together, this synthesis highlights the broad link between community structure and disease while underscoring the importance of mitigating ongoing changes in biological communities owing to species introductions and extirpations. PMID:20190121

Johnson, P T J; Thieltges, D W

2010-03-15

207

The legacy of domestication: accumulation of deleterious mutations in the dog genome.  

PubMed

Dogs exhibit more phenotypic variation than any other mammal and are affected by a wide variety of genetic diseases. However, the origin and genetic basis of this variation is still poorly understood. We examined the effect of domestication on the dog genome by comparison with its wild ancestor, the gray wolf. We compared variation in dog and wolf genes using whole-genome single nucleotide polymorphism (SNP) data. The d(N)/d(S) ratio (omega) was around 50% greater for SNPs found in dogs than in wolves, indicating that a higher proportion of nonsynonymous alleles segregate in dogs compared with nonfunctional genetic variation. We suggest that the majority of these alleles are slightly deleterious and that two main factors may have contributed to their increase. The first is a relaxation of selective constraint due to a population bottleneck and altered breeding patterns accompanying domestication. The second is a reduction of effective population size at loci linked to those under positive selection due to Hill-Robertson interference. An increase in slightly deleterious genetic variation could contribute to the prevalence of disease in modern dog breeds. PMID:18689870

Cruz, Fernando; Vilà, Carles; Webster, Matthew T

2008-08-09

208

Ecological and genetic effects of introduced species on their native competitors.  

PubMed

Species introductions to new habitats can cause a decline in the population size of competing native species and consequently also in their genetic diversity. We are interested in why these adverse effects are weak in some cases whereas in others the native species declines to the point of extinction. While the introduction rate and the growth rate of the introduced species in the new environment clearly have a positive relationship with invasion success and impact, the influence of competition is poorly understood. Here, we investigate how the intensity of interspecific competition influences the persistence time of a native species in the face of repeated and ongoing introductions of the nonnative species. We analyze two stochastic models: a model for the population dynamics of both species and a model that additionally includes the population genetics of the native species at a locus involved in its adaptation to a changing environment. Counterintuitively, both models predict that the persistence time of the native species is lowest for an intermediate intensity of competition. This phenomenon results from the opposing effects of competition at different stages of the invasion process: With increasing competition intensity more introduction events are needed until a new species can establish, but increasing competition also speeds up the exclusion of the native species by an established nonnative competitor. By comparing the ecological and the eco-genetic model, we detect and quantify a synergistic feedback between ecological and genetic effects. PMID:23231882

Wittmann, Meike J; Hutzenthaler, Martin; Gabriel, Wilfried; Metzler, Dirk

2012-12-08

209

Effect of hypochloride on microbial ecology of bulking and foaming activated sludge treatment for tannery wastewater.  

PubMed

This study investigates the effect of hypochloride application for controlling bulking and foaming on the microbial ecology of an activated sludge system treating tannery wastewater. Detailed characterization of the wastewater treatment influent and effluent is also reported for the study period. During the study, bulking and foaming are first monitored with a sudden burst in the sludge volume index over 250 mL g(-1), creating a significant deterioration of the effluent quality. The corresponding upset in the microbial ecology is the combined excessive proliferation of M. parvicella, N. limicola II and Gordona (Nocardia) spp., but mainly triggered by Gordona contamination of the floc structure and the rapid outward growth of this filamentous microorganism extending to adjacent flocs. Chlorine application at an average rate of 3 g Cl(-1)(kg MLSS.day)(-1) for 12 days provide an effective solution for bulking and foaming, restoring the effluent quality. It destroys filamentous texture between the flocs, leaving only a lot of loose and chopped filament fragments and, totally removes the Gordona spp. from solution which retrieves back into the flocs. Therefore, chlorine remediation of bulking and foaming, although temporarily effective, is only superficial as the Gordona seeding inside the floc remains intact and potentially available for excessive growth in the next favorable conditions. PMID:17018406

Ovez, Süleyman; Ors, Canan; Murat, Selda; Orhon, Derin

2006-01-01

210

Scale-dependent effect sizes of ecological drivers on biodiversity: why standardised sampling is not enough.  

PubMed

There is little consensus about how natural (e.g. productivity, disturbance) and anthropogenic (e.g. invasive species, habitat destruction) ecological drivers influence biodiversity. Here, we show that when sampling is standardised by area (species density) or individuals (rarefied species richness), the measured effect sizes depend critically on the spatial grain and extent of sampling, as well as the size of the species pool. This compromises comparisons of effects sizes within studies using standard statistics, as well as among studies using meta-analysis. To derive an unambiguous effect size, we advocate that comparisons need to be made on a scale-independent metric, such as Hurlbert's Probability of Interspecific Encounter. Analyses of this metric can be used to disentangle the relative influence of changes in the absolute and relative abundances of individuals, as well as their intraspecific aggregations, in driving differences in biodiversity among communities. This and related approaches are necessary to achieve generality in understanding how biodiversity responds to ecological drivers and will necessitate a change in the way many ecologists collect and analyse their data. PMID:23679009

Chase, Jonathan M; Knight, Tiffany M

2013-05-01

211

Pleistocene and ecological effects on continental-scale genetic differentiation in the bobcat (Lynx rufus).  

PubMed

The potential for widespread, mobile species to exhibit genetic structure without clear geographic barriers is a topic of growing interest. Yet the patterns and mechanisms of structure--particularly over broad spatial scales--remain largely unexplored for these species. Bobcats occur across North America and possess many characteristics expected to promote gene flow. To test whether historical, topographic or ecological factors have influenced genetic differentiation in this species, we analysed 1 kb mtDNA sequence and 15 microsatellite loci from over 1700 samples collected across its range. The primary signature in both marker types involved a longitudinal cline with a sharp transition, or suture zone, occurring along the Great Plains. Thus, the data distinguished bobcats in the eastern USA from those in the western half, with no obvious physical barrier to gene flow. Demographic analyses supported a scenario of expansion from separate Pleistocene refugia, with the Great Plains representing a zone of secondary contact. Substructure within the two main lineages likely reflected founder effects, ecological factors, anthropogenic/topographic effects or a combination of these forces. Two prominent topographic features, the Mississippi River and Rocky Mountains, were not supported as significant genetic barriers. Ecological regions and environmental correlates explained a small but significant proportion of genetic variation. Overall, results implicate historical processes as the primary cause of broad-scale genetic differentiation, but contemporary forces seem to also play a role in promoting and maintaining structure. Despite the bobcat's mobility and broad niche, large-scale landscape changes have contributed to significant and complex patterns of genetic structure. PMID:22548482

Reding, Dawn M; Bronikowski, Anne M; Johnson, Warren E; Clark, William R

2012-04-30

212

Florida acid-deposition study. A literature review of the ecological and material effects of acid deposition  

SciTech Connect

The ecological and material effects of acid deposition have been a point of concern in the U.S. because of conflicting information regarding the nature of these impacts, not only negative effects, but also positive effects. Phase I of the Ecological and Material Effects program was designed to initiate a better definition of the concern by evaluating the current literature regarding the ecological and material effects of acid deposition and its relevancy to Florida. Among the objectives accomplished by this program during Phase I were: (1) implementation of literature search and evaluations; and (2) identification of the limitations of various approaches to addressing the basic objectives, and assessment of these approaches in terms of their applicability to Florida. This report presents the results of the Phase I analysis.

Newman, J.R.; Fletcher, S.W.; Hendry, C.D.; Pollman, C.D.; Carter, L.C.

1982-01-01

213

Effect of Collectivist Orientation and Ecological Attitude on Actual Environmental Commitment  

Microsoft Academic Search

Despite previous research efforts on mapping the demographic profile of a general conserving consumer, a review on the ecological concern literature shows that previous studies had limited success in explaining the social basis of ecological behaviour. An empirical study was carried out to ascertain the role of demographics in determining ecological purchase commitment. It examines the moderating role of consumer

Li Ling-Yee

1997-01-01

214

Effects of ozone depletion and UV?B radiation on humans and the environment  

Microsoft Academic Search

There are important effects of changes in the intensity of solar UV ?radiation resulting from stratospheric ozone depletion, particularly UV?B radiation, on all organisms on the planet. Biological and ecological responses to increases in UV?B radiation may be deleterious and result in harm to humans, particularly in terms of the incidence of cataracts of the eye and cancers of the

Keith R. Solomon

2008-01-01

215

[Ecological effect of different types land consolidation in Hubei Province of China].  

PubMed

A model for estimating the ecosystem services value under effects of land consolidation was built to quantitatively evaluate the ecological effects of three different types of land consolidation projects in Jianghan Plain, middle hilly region, and western mountainous area of Hubei Province. With the implementation of the projects, the total value of ecosystem services in Jianghan Plain was decreased by 0.3%, among which, the values of food production service and other three services increased but those of water conservation and other four services decreased. In hilly region, the total value of ecosystem services was decreased by 14.6%, with the value of food production service increased by 55.2% and those of other eight services all decreased. In mountainous area, the total value of ecosystem services was decreased by 19.9%, with the value of food production service increased by 24.9% while the values of other eight services all decreased. In the land consolidation in the middle hilly region and western mountainous area of Hubei Province, there was an obvious conversion process 'from ecology to production' in the ecosystem services value. PMID:23189708

Gu, Xiao-Kun

2012-08-01

216

The Effect of an Ecological Imagery Program on Soccer Performance of Elite Players  

PubMed Central

Purpose Despite the acknowledged impact of imagery on performance, ecologically sound studies investigating imagery and its effects on performance subcomponents in real games are surprisingly limited. The aim of this study was to investigate the effects of imagery training on passing improvement in elite soccer players. Methods Sixty nine soccer players taking part in the national championship leagues in four age categories including U16, U19, U21 and over 21 were randomly assigned to the imagery and control groups. Interventional group participants completed an 8 week video-aided, cognitive imagery program on how to make a perfect soccer pass. Results Performance analysis through close video analysis showed that successful pass rate increased significantly in the intervention group compared to control (OR = 1.19, P=0.002, 95%CI = 1.06-1.33). Further analysis revealed that the results are statistically significant in U16 and U21 but not other categories. Conclusions We concluded that successful soccer passing through real competitions as a multidimensional and critical open skill could be enhanced by an ecologically sound method of mental imagery.

Seif-Barghi, Tohid; Kordi, Ramin; Memari, Amir-Hossein; Mansournia, Mohammad-Ali; Jalali-Ghomi, Majid

2012-01-01

217

Ecological impacts of umbrella effects of radiation on the individual members.  

PubMed

In order to study the interactions in a model aquatic microcosm, an individual-based computer simulation model was developed. The microcosm consists of Euglena gracilis as an autotroph algae, Tetrahymena thermophila as a heterotroph protozoa and Escherichia coli as a saprotroph bacteria. There exists a strong interaction between Tetrahymena and E. coli as the first is the predator of the second. Ecological toxicity tests were conducted to test the population level impacts of the biological effects of radiation and toxicants on the lethality and mobility factors that influence directly or indirectly growth and reproduction. Radiological effects on lethality of E. coli individuals were translated to the reduction of the equilibrium population of Tetrahymena. A synergistic effect at the community level was also observed by the simulation of a combined exposure of radiation and a toxicant which reduced the feeding efficiency of Tetrahymena. PMID:17459541

Doi, Masahiro; Kawaguchi, Isao

2007-04-24

218

Face adaptation effects show strong and long-lasting transfer from lab to more ecological contexts.  

PubMed

A review on recent experiments on figural face aftereffects reveals that adaptation effects in famous faces can last for hours up to days. Such adaptations seem to be highly reliable regarding test-retest designs as well as regarding the generalizability of adaptation across different adaptation routines and adaptations toward different kinds of facial properties. However, in the studies conducted so far, adaptation and the subsequent test phase were carried out in typical laboratory environments. Under these circumstances, it cannot be ruled out that the observed effects are, in fact, episodic learn-test compatibility effects. To test for ecological validity in adaptation effects we used an adaptation paradigm including environmental and social properties that differed between adaptation and test phase. With matched samples (n1?=?n2?=?54) we found no main effects of experimental setting compatibility resulting from varying where the tests where conducted (environmental condition) nor any interaction with effects of stimulus compatibility resulting from varying stimulus similarity between adaptation and test phase using the same picture, different pictures of the same person, or different persons (transfer). This indicates that these adaptation effects are not artificial or merely lab-biased effects. Adaptation to face stimuli may document representational adaptations and tuning mechanisms that integrate new visual input in a very fast, reliable, and sustainable way. PMID:22291676

Carbon, Claus-Christian; Ditye, Thomas

2012-01-24

219

Evaluating Ecological Effects in a Semi-arid Aquatic System Using Three Lines of Evidence  

NASA Astrophysics Data System (ADS)

One mission of Los Alamos National Laboratory has been to develop explosives, machine explosive charges, and test explosive components for the United States nuclear weapons program. Effluents containing high explosives and metals from machining and photographic facilities were discharged to Canon de Valle for forty years at rates up to ten million gallons per year, making up as much as half of the canyon's flow. Discharges to the canyon were discontinued in 1996. Canon de Valle has an interrupted stream that supports an herbaceous ground cover and a multi-layer canopy of conifers, oak and aspen. An ecological screening assessment and problem formulation identified barium, cadmium, copper, manganese and silver as metals of potential ecological concern for the aquatic system in the canyon. Additionally, potential impacts associated with high explosives in the aquatic system are unknown because aquatic community screening values are not available. Two field studies were designed and implemented to assess the adverse effects in the canyon's aquatic system. The first field study consisted of benthic macro-invertebrate surveys that were conducted in Canon de Valle and three reference streams. The survey was then repeated in Canon de Valle four years later to assess trends in the benthic macro-invertebrate community. The second field study consisted of toxicity testing with {it Chironomus tentans} using three locations in the Canon de Valle and one location in a reference canyon. Two rounds of toxicity testing were conducted. Each round was supported with sediment and water sampling at each location for contaminant analysis. The data from the contaminant analysis of water and sediments will be presented along with the results of the benthic macro-invertebrate surveys and the toxicity tests. An example of identifying the contaminants associated with reduced survival in a toxicity test will presented, the utility of benthic macro-invertebrate community metrics as indicators of adverse ecological effects will be discussed, and the relative importance of these three lines of evidence for assessing adverse effects in the canyon's aquatic system will be discussed.

Tardiff, M. F.; Ford-Schmid, R.; Hickmott, D. D.

2003-12-01

220

A Daphnia magna feeding bioassay as a cost effective and ecological relevant sublethal toxicity test for Environmental Risk Assessment of toxic effluents  

Microsoft Academic Search

Environmental Risk Assessment of chemical products and effluents within EC countries require the use of cost effective standardized toxicity tests that in most cases are restricted to acute responses to high doses. Thus, subtle ecological effects are underestimated. Here we propose a short-term one day Daphnia magna feeding inhibition test as a cost effective and ecological relevant sublethal bioassay. The

C. Barata; P. Alañon; S. Gutierrez-Alonso; M. C. Riva; C. Fernández; J. V. Tarazona

2008-01-01

221

Causes and ecological effects of resuspended contaminated sediments (RCS) in marine environments.  

PubMed

Sediments act as a net sink for anthropogenic contaminants in marine ecosystems and contaminated sediments may have a range of toxicological effects on benthic fauna and associated species. When resuspended, however, particulate-bound contaminants may be remobilised into the water column and become bioavailable to an additional assemblage of species. Such resuspension occurs through a range of natural and anthropogenic processes each of which may be thought of as pulsed disturbances resulting in pulsed exposures to contaminants. Thus, it is important to understand not only the toxicological responses of organisms to resuspended contaminated sediments (RCS), but also the frequency, magnitude and duration of sediment disturbance events. Such information is rarely collected together with toxicological data. Rather, the majority of published studies (>50% of the articles captured in this review) have taken the form of fixed-duration laboratory-based exposures with individual species. While this research has clearly demonstrated that resuspension of contaminated sediments can liberate sediment-bound contaminants leading to toxicity and bioaccumulation under controlled conditions, the potential for ecological effects in the field is often unclear. Monitoring studies suggest that recurrent natural disturbances such as tides and waves may cause the majority of contaminant release in many environments. However, various processes also act to limit the spatial and temporal scales across which contaminants are remobilised to the most toxic dissolved state. Various natural and anthropogenic disturbances of contaminated sediments have been linked to both community-level and sub-lethal responses in exposed populations of invertebrates and fish in the field. Together these findings suggest that resuspension of contaminated sediments is a frequently recurring ecological threat in contaminated marine habitats. Further consideration of how marine communities respond to temporally variable exposures to RCS is required, as well as research into the relative importance of various disturbances under field conditions. PMID:22244126

Roberts, David A

2012-01-13

222

Effects of harvest of nontimber forest products and ecological differences between sites on the demography of African mahogany.  

PubMed

The demographic impacts of harvesting nontimber forest products (NTFP) have been increasingly studied because of reports of potentially unsustainable harvest. Nevertheless, our understanding of how plant demographic response to harvest is altered by variation in ecological conditions, which is critical for developing realistic sustainable-use plans, is limited. We built matrix population models to test whether and how variation in ecological conditions affects population responses to harvest. In particular, we examined the effect of bark and foliage harvest on the demography of populations of African mahogany (Khaya senegalensis) in two contrasting ecological regions of Benin, West Africa. K. senegalensis bark and foliage harvest significantly reduced its stochastic population growth rates, but ecological differences between regions had a greater effect on population growth rates than did harvest. The effect of harvest on population growth rates (Deltalambda) was slightly stronger in the moist than in the drier region. Life-table response experiments revealed that the mechanism by which harvesting reduced lambda differed between ecological regions. Lowered stasis (persistence) of larger life stages lead to a reduction in lambda in the drier region, whereas lowered growth of all life stages lowered lambda in moist region. Potential strategies to increase population growth rates should include decreasing the proportion of individuals harvested, promoting harvester-owned plantations of African mahogany, and increasing survival and growth by promoting no-fire zones in gallery forests. Our results show how population responses to harvest of NTFP may be altered by ecological differences across sites and emphasize the importance of monitoring populations over the climatic range in which they occur to develop more realistic recommendations for conservation. PMID:19843124

Gaoue, Orou G; Ticktin, Tamara

2009-10-16

223

Transport, transformation and ecological effects of phosphorus smokes in an environmental wind tunnel  

SciTech Connect

An evaluation of the terrestrial transport, transformations and ecological effects of phosphorus (red phosphorus-butyl rubber (RP/BR)), smoke/obscurant was performed to characterize the effects on: (1) natural vegetation characteristic of US Army training sites in the United States; (2) physical and chemical properties of representative of soils of those sites; and (3) soil microbiological communities. The influence and interactions of smoke/obscurant concentration relative humidity and wind speed was assessed. Toxicity symptoms for plants from repeated or a single exposure included leaf tip burn, leaf curl, leaf abscission and drop, floral abortion, chlorosis, neucrotic spotting, wilting, dessication and dieback for ponderosa pine, short needle pine, sagebrush, a native grass (Blando Brome) and bushbean. Soils data suggest an increase in the mobility of selected trace elements after exposure; however, this effect appears to be ameliorated with time. This phenomenon is influenced by soil type, which is a reflection of the buffering capacity of the exposed soil (i.e., Burbank, Quallayute, Shawano, and Yamac) as well as the concentration and duration of exposure. Increased mobility of trace elements is also evidenced in the trace element content of plants grown on soils after exposure to RP/BR smoke. Soil Microbial Community effects show a reduction in the production of nitrate after soil is exposed to RP/BR smoke. This indicates a reduction in ammonium oxidizing bacterial populations, specifically Nitrosomonas and probably Nitrobacter. For the most part most of the plant, soil and soil microbial effects are transient.

Van Voris, P.; Cataldo, D.A.; Garland, T.R.; Ligotke, M.W.; Rogers, J.E.; McFadden, K.M.; Carlile, D.W.; Li, S.W.

1985-04-01

224

Effective sociodemographic population assessment of elusive species in ecology and conservation management  

PubMed Central

Wildlife managers are urgently searching for improved sociodemographic population assessment methods to evaluate the effectiveness of implemented conservation activities. These need to be inexpensive, appropriate for a wide spectrum of species and straightforward to apply by local staff members with minimal training. Furthermore, conservation management would benefit from single approaches which cover many aspects of population assessment beyond only density estimates, to include for instance social and demographic structure, movement patterns, or species interactions. Remote camera traps have traditionally been used to measure species richness. Currently, there is a rapid move toward using remote camera trapping in density estimation, community ecology, and conservation management. Here, we demonstrate such comprehensive population assessment by linking remote video trapping, spatially explicit capture–recapture (SECR) techniques, and other methods. We apply it to three species: chimpanzees Pan troglodytes troglodytes, gorillas Gorilla gorilla gorilla, and forest elephants Loxodonta cyclotis in Loango National Park, Gabon. All three species exhibited considerable heterogeneity in capture probability at the sex or group level and density was estimated at 1.72, 1.2, and 1.37 individuals per km2 and male to female sex ratios were 1:2.1, 1:3.2, and 1:2 for chimpanzees, gorillas, and elephants, respectively. Association patterns revealed four, eight, and 18 independent social groups of chimpanzees, gorillas, and elephants, respectively: key information for both conservation management and studies on the species' ecology. Additionally, there was evidence of resident and nonresident elephants within the study area and intersexual variation in home range size among elephants but not chimpanzees. Our study highlights the potential of combining camera trapping and SECR methods in conducting detailed population assessments that go far beyond documenting species diversity patterns or estimating single species population size. Our study design is widely applicable to other species and spatial scales, and moderately trained staff members can collect and process the required data. Furthermore, assessments using the same method can be extended to include several other ecological, behavioral, and demographic aspects: fission and fusion dynamics and intergroup transfers, birth and mortality rates, species interactions, and ranging patterns.

Head, Josephine S; Boesch, Christophe; Robbins, Martha M; Rabanal, Luisa I; Makaga, Loic; Kuhl, Hjalmar S

2013-01-01

225

Effective sociodemographic population assessment of elusive species in ecology and conservation management.  

PubMed

Wildlife managers are urgently searching for improved sociodemographic population assessment methods to evaluate the effectiveness of implemented conservation activities. These need to be inexpensive, appropriate for a wide spectrum of species and straightforward to apply by local staff members with minimal training. Furthermore, conservation management would benefit from single approaches which cover many aspects of population assessment beyond only density estimates, to include for instance social and demographic structure, movement patterns, or species interactions. Remote camera traps have traditionally been used to measure species richness. Currently, there is a rapid move toward using remote camera trapping in density estimation, community ecology, and conservation management. Here, we demonstrate such comprehensive population assessment by linking remote video trapping, spatially explicit capture-recapture (SECR) techniques, and other methods. We apply it to three species: chimpanzees Pan troglodytes troglodytes, gorillas Gorilla gorilla gorilla, and forest elephants Loxodonta cyclotis in Loango National Park, Gabon. All three species exhibited considerable heterogeneity in capture probability at the sex or group level and density was estimated at 1.72, 1.2, and 1.37 individuals per km(2) and male to female sex ratios were 1:2.1, 1:3.2, and 1:2 for chimpanzees, gorillas, and elephants, respectively. Association patterns revealed four, eight, and 18 independent social groups of chimpanzees, gorillas, and elephants, respectively: key information for both conservation management and studies on the species' ecology. Additionally, there was evidence of resident and nonresident elephants within the study area and intersexual variation in home range size among elephants but not chimpanzees. Our study highlights the potential of combining camera trapping and SECR methods in conducting detailed population assessments that go far beyond documenting species diversity patterns or estimating single species population size. Our study design is widely applicable to other species and spatial scales, and moderately trained staff members can collect and process the required data. Furthermore, assessments using the same method can be extended to include several other ecological, behavioral, and demographic aspects: fission and fusion dynamics and intergroup transfers, birth and mortality rates, species interactions, and ranging patterns. PMID:24101982

Head, Josephine S; Boesch, Christophe; Robbins, Martha M; Rabanal, Luisa I; Makaga, Loïc; Kühl, Hjalmar S

2013-07-30

226

Ecological effects of water retention in the River Rhine valley: a review assisting future retention basin classification  

Microsoft Academic Search

This review paper summarizes the ecological effects of the use of floodplains and flood retention basins to control river flow in the River Rhine (Rhein) valley. Early River Rhine regulation strategies including channel straightening are assessed. The subsequent disappearance of alluvial hardwood forests has been highlighted as the major disadvantage. The response of trees to more recent strategies such as

M. Scholz

2007-01-01

227

Does Parenting Mediate the Effects of Exposure to Violence on Violent Behavior? An Ecological-Transactional Model of Community Violence  

ERIC Educational Resources Information Center

|Three waves of longitudinal data from a high poverty sample of 1544 African American youth were used to test an ecological-transactional model of violence. SEM analyses were conducted to determine whether parenting (Time 2) mediated the effects of exposure to violence (Time 1) on violent behaviors (Time 3). Findings supported the specified model.…

Spano, Richard; Vazsonyi, Alexander T.; Bolland, John

2009-01-01

228

Does parenting mediate the effects of exposure to violence on violent behavior? An ecological–transactional model of community violence  

Microsoft Academic Search

Three waves of longitudinal data from a high poverty sample of 1544 African American youth were used to test an ecological–transactional model of violence. SEM analyses were conducted to determine whether parenting (Time 2) mediated the effects of exposure to violence (Time 1) on violent behaviors (Time 3). Findings supported the specified model. Multigroup SEM analyses indicated that neither family

Richard Spano; Alexander T. Vazsonyi; John Bolland

2009-01-01

229

DEVELOPMENT OF PROTEIN PROFILE TECHNOLOGY TO EVALUATE ECOLOGICAL EFFECTS OF ENVIRONMENTAL CHEMICALS USING A SMALL FISH MODEL  

EPA Science Inventory

Hemmer, Michael J., Robert T. Hudson and Calvin C. Walker. In press. Development of Protein Profile Technology to Evaluate Ecological Effects of Environmental Chemicals Using a Small Fish Model (Abstract). To be presented at the EPA Science Forum: Healthy Communities and Ecosyste...

230

Effect of feeding fermented liquid feed and fermented grain on gastrointestinal ecology and growth performance in piglets  

Microsoft Academic Search

To investigate the microbial and nutri- tional characteristics of dry feed, liquid feed containing fermented liquid cereal grains, and fermented liquid feed, and their effect on gastrointestinal ecology and growth performance, 120 piglets from 40 litters were used and housed in pens with 5 animals in each. The 3 dietary treatments (all nonheated and nonpelleted diets) were: a dry meal

N. Canibe; O. Højberg; J. H. Badsberg; B. B. Jensen

2010-01-01

231

Lawrence Livermore National Laboratory interests and capabilities for research on the ecological effects of global climatic and atmospheric change  

SciTech Connect

The Lawrence Livermore National Laboratory (LLNL) has interests and capabilities in all three types of research that must be conducted in order to understand and predict effects of global atmospheric and climatic (i.e., environmental) changes on ecological systems and their functions (ecosystem function is perhaps most conveniently defined as mass and energy exchange and storage). These three types of research are: (1) manipulative experiments with plants and ecosystems; (2) monitoring of present ecosystem, landscape, and global exchanges and pools of energy, elements, and compounds that play important roles in ecosystem function or the physical climate system, and (3) mechanistic (i.e., hierarchic and explanatory) modeling of plant and ecosystem responses to global environmental change. Specific experimental programs, monitoring plans, and modeling activities related to evaluation of ecological effects of global environmental change that are of interest to, and that can be carried out by LLNL scientists are outlined. Several projects have the distinction of integrating modeling with empirical studies resulting in an Integrated Product (a model or set of models) that DOE or any federal policy maker could use to assess ecological effects. The authors note that any scheme for evaluating ecological effects of atmospheric and climatic change should take into account exceptional or sensitive species, in particular, rare, threatened, or endangered species.

Amthor, J.S.; Houpis, J.L.; Kercher, J.R.; Ledebuhr, A.; Miller, N.L.; Penner, J.E.; Robison, W.L.; Taylor, K.E.

1994-09-01

232

ECOLOGICAL INDICATORS  

EPA Science Inventory

An international symposium on ecological indicators was developed to explore both the potential of ecological indicators and the issues surrounding their development and implementation. his symposium presented state-of-the-science information on the identification, application re...

233

The Effect of Inappropriate Calibration: Three Case Studies in Molecular Ecology  

Microsoft Academic Search

Time-scales estimated from sequence data play an important role in molecular ecology. They can be used to draw correlations between evolutionary and palaeoclimatic events, to measure the tempo of speciation, and to study the demographic history of an endangered species. In all of these studies, it is paramount to have accurate estimates of time-scales and substitution rates. Molecular ecological studies

Simon Y. W. Ho; Urmas Saarma; Ross Barnett; James Haile; Beth Shapiro; Peter Bennett

2008-01-01

234

Expected effects of the ecological tax reform for the Polish economy  

Microsoft Academic Search

This study presents an assessment of possible consequences of ecological tax reform for the Polish economy. Computable general equilibrium model has been used. The model calibrated for the base year 1995 provides results for the year 2005. Six different scenarios have been considered. Final results confirm both theoretical and practical implications of the ecological tax reforms experiences in Western European

Olga Kiuila; Jerzy Sleszynski

2003-01-01

235

The ecological effect of phenotypic plasticity - Analyzing complex interaction networks (COIN) with agent-based models  

Microsoft Academic Search

Analyzing complex dynamics of ecological systems is complicated by two important facts: First, phenotypic plasticity allows individual organisms to adapt their reaction norms in terms of morphology, anatomy, physiology and behavior to changing local environmental conditions and trophic relationships. Secondly, individual reactions and ecological dynamics are often determined by indirect interactions through reaction chains and networks involving feedback processes.We present

H. Reuter; F. Jopp; F. Hölker; C. Eschenbach; U. Middelhoff; Broder Breckling

2008-01-01

236

Effects of Ecological Information on Judgments about Scenic Impacts of Timber Harvest  

Microsoft Academic Search

The public is unlikely to accept ecosystem management practices unless they believe its ecological benefits outweigh its potentially adverse impacts. This study tested whether information about ecological benefits of ecosystem management can improve acceptance of impacts to visual resources. Students and office workers rated photographs of forest stands showing traditional and ecosystem management timber harvests. Half of the respondents first

Mark W. Brunson; Douglas K. Reiter

1996-01-01

237

Ecological effectiveness of French grassland agri-environment schemes for farmland bird communities.  

PubMed

Agri-environment schemes (AES) have been implemented to cope with the loss of farmland biodiversity due to agricultural intensification over the last decades. In France, grassland measures (more closely linked to extensive grazing) are the most widely implemented within the French AES, and are presumably those whose effectiveness can be better assessed. In this paper, we have evaluated the effectiveness of French grassland agri-environmental measures (gAES) to enhance farmland bird diversity on a national scale, using local abundances of 19 farmland breeding birds within 463 Small Agricultural Regions (SAR) covering France during 2001-2008. We modeled responses of species abundances and estimated species richness to five categories of grassland AES, accounting for the characteristics of local production systems. Extensive management of grasslands had a positive effect on species richness. Despite mixed results on the effectiveness of the different grassland AES categories, our results are optimistic in terms of the ability of some French AES to provide benefits to birds. It seems that some grassland AES have achieved their objectives while meeting species ecological requirements. Moreover, this study highlights the fact that some of these grassland AES have the potential to enhance the population dynamics of declining species. Finally, although they all aim at benefitting biodiversity, it cannot be assumed that grassland measures lead to uniform conservation benefits. PMID:23535512

Princé, Karine; Jiguet, Frédéric

2013-03-25

238

Backyard Ecology.  

ERIC Educational Resources Information Center

Describes the Ecology Explorers, the community education component of Arizona State University's Central Arizona Phoenix Long-Term Ecological Research project, which offers teacher internship programs that link university researchers, K-12 teachers, and students in studying urban ecology. Explains that student neighborhoods are dynamic ecosystems…

Elser, Monica; Musheno, Birgit; Saltz, Charlene

2003-01-01

239

Ecological Footprint  

NSDL National Science Digital Library

Students explore their own Ecological Footprint in the context of how many Earths it would take if everyone used the same amount of resources they did. They compare this to the Ecological Footprint of individuals in other parts of the world and to the Ecological footprint of a family member when they were the student's age.

2007-01-01

240

Backyard Ecology.  

ERIC Educational Resources Information Center

|Describes the Ecology Explorers, the community education component of Arizona State University's Central Arizona Phoenix Long-Term Ecological Research project, which offers teacher internship programs that link university researchers, K-12 teachers, and students in studying urban ecology. Explains that student neighborhoods are dynamic ecosystems…

Elser, Monica; Musheno, Birgit; Saltz, Charlene

2003-01-01

241

An Application of a Mixed-Effects Location Scale Model for Analysis of Ecological Momentary Assessment (EMA) Data  

Microsoft Academic Search

Summary. For longitudinal data,mixed models include random subject effects to indicate how subjects influence their responses over repeated assessments. The error variance and the variance of the random effects are usually considered to be homogeneous. These variance terms characterize the within-subjects (i.e.,error variance) and between-subjects (i.e.,random-effects variance) variation in the data. In studies using ecological momentary assessment (EMA),up to 30

Donald Hedeker; Robin J. Mermelstein; Hakan Demirtas

2008-01-01

242

Environmental assessment for the satellite power system-concept development and evaluation program-microwave health and ecological effects  

SciTech Connect

This report is concerned with the potential health and ecological effects of the microwave beam from the microwave power transmission system (MPTS) of the satellite power system (SPS). The report is written in the form of a detailed critical review of selected scientific articles from the published literature on the biological effects of nonionizing electromagnetic radiation, followed by an assessment of the possible effects of the SPS, based on exposure values for the reference system (US DOE and NASA, 1978).

Not Available

1980-11-01

243

Deleterious- and Disease-Allele Prevalence in Healthy Individuals: Insights from Current Predictions, Mutation Databases, and Population-Scale Resequencing  

PubMed Central

We have assessed the numbers of potentially deleterious variants in the genomes of apparently healthy humans by using (1) low-coverage whole-genome sequence data from 179 individuals in the 1000 Genomes Pilot Project and (2) current predictions and databases of deleterious variants. Each individual carried 281–515 missense substitutions, 40–85 of which were homozygous, predicted to be highly damaging. They also carried 40–110 variants classified by the Human Gene Mutation Database (HGMD) as disease-causing mutations (DMs), 3–24 variants in the homozygous state, and many polymorphisms putatively associated with disease. Whereas many of these DMs are likely to represent disease-allele-annotation errors, between 0 and 8 DMs (0–1 homozygous) per individual are predicted to be highly damaging, and some of them provide information of medical relevance. These analyses emphasize the need for improved annotation of disease alleles both in mutation databases and in the primary literature; some HGMD mutation data have been recategorized on the basis of the present findings, an iterative process that is both necessary and ongoing. Our estimates of deleterious-allele numbers are likely to be subject to both overcounting and undercounting. However, our current best mean estimates of ?400 damaging variants and ?2 bona fide disease mutations per individual are likely to increase rather than decrease as sequencing studies ascertain rare variants more effectively and as additional disease alleles are discovered.

Xue, Yali; Chen, Yuan; Ayub, Qasim; Huang, Ni; Ball, Edward V.; Mort, Matthew; Phillips, Andrew D.; Shaw, Katy; Stenson, Peter D.; Cooper, David N.; Tyler-Smith, Chris

2012-01-01

244

Ecological contingency in the effects of climatic warming on forest herb communities.  

PubMed

Downscaling from the predictions of general climate models is critical to current strategies for mitigating species loss caused by climate change. A key impediment to this downscaling is that we lack a fully developed understanding of how variation in physical, biological, or land-use characteristics mediates the effects of climate change on ecological communities within regions. We analyzed change in understory herb communities over a 60-y period (1949/1951-2007/2009) in a complex montane landscape (the Siskiyou Mountains, Oregon) where mean temperatures have increased 2 °C since 1948, similar to projections for other terrestrial communities. Our 185 sites included primary and secondary-growth lower montane forests (500-1.200 m above sea level) and primary upper montane to subalpine forests (1,500-2,100 m above sea level). In lower montane forests, regardless of land-use history, we found multiple herb-community changes consistent with an effectively drier climate, including lower mean specific leaf area, lower relative cover by species of northern biogeographic affinity, and greater compositional resemblance to communities in southerly topographic positions. At higher elevations we found qualitatively different and more modest changes, including increases in herbs of northern biogeographic affinity and in forest canopy cover. Our results provide community-level validation of predicted nonlinearities in climate change effects. PMID:20974978

Harrison, Susan; Damschen, Ellen I; Grace, James B

2010-10-25

245

Divergent ecological effects of oceanographic anomalies on terrestrial ecosystems of the Mexican Pacific coast  

PubMed Central

Precipitation pulses are essential for the regeneration of drylands and have been shown to be related to oceanographic anomalies. However, whereas some studies report increased precipitation in drylands in northern Mexico during El Niño years, others report increased drought in the southern drylands. To elucidate the effect of oceanographic/atmospheric anomalies on moisture pulses along the whole Pacific coast of Mexico, we correlated the average Southern Oscillation Index values with total annual precipitation for 117 weather stations. We also analyzed this relationship for three separate rainfall signals: winter-spring, summer monsoon, and fall precipitation. The results showed a distinct but divergent seasonal pattern: El Niño events tend to bring increased rainfall in the Mexican northwest but tend to increase aridity in the ecosystems of the southern tropical Pacific slope. The analysis for the separated rainfall seasons showed that El Niño conditions produce a marked increase in winter rainfall above 22° latitude, whereas La Niña conditions tend to produce an increase in the summer monsoon-type rainfall that predominates in the tropical south. Because these dryland ecosystems are dependent on rainfall pulses for their renewal, understanding the complex effect of ocean conditions may be critical for their management in the future. Restoration ecology, grazing regimes, carrying capacities, fire risks, and continental runoff into the oceans could be predicted from oceanographic conditions. Monitoring the coupled atmosphere–ocean system may prove to be important in managing and mitigating the effects of large-scale climatic change on coastal drylands in the future.

Caso, Margarita; Gonzalez-Abraham, Charlotte; Ezcurra, Exequiel

2007-01-01

246

Salinity and Temperature Effects on Physiological Responses of Vibrio fischeri from Diverse Ecological Niches  

PubMed Central

Vibrio fischeri is a bioluminescent bacterial symbiont of sepiolid squids (Cephalopoda: Sepiolidae) and monocentrid fishes (Actinopterygii: Monocentridae). V. fischeri exhibit competitive dominance within the allopatrically distributed squid genus Euprymna, which have led to the evolution of V. fischeri host specialists. In contrast, the host genus Sepiola contains sympatric species that is thought to have given rise to V. fischeri that have evolved as host generalists. Given that these ecological lifestyles may have a direct effect upon the growth spectrum and survival limits in contrasting environments, optimal growth ranges were obtained for numerous V. fischeri isolates from both free-living and host environments. Upper and lower limits of growth were observed in sodium chloride concentrations ranging from 0.0% to 9.0%. Sepiola symbiotic isolates possessed the least variation in growth throughout the entire salinity gradient, whereas isolates from Euprymna were the least uniform at <2.0% NaCl. V. fischeri fish symbionts (CG101 and MJ101) and all free-living strains were the most dissimilar at >5.0% NaCl. Growth kinetics of symbiotic V. fischeri strains were also measured under a range of salinity and temperature combinations. Symbiotic V. fischeri ES114 and ET101 exhibited a synergistic effect for salinity and temperature, where significant differences in growth rates due to salinity existed only at low temperatures. Thus, abiotic factors such as temperature and salinity have differential effects between free-living and symbiotic strains of V. fischeri, which may alter colonization efficiency prior to infection.

Soto, W.; Gutierrez, J.; Remmenga, M. D.; Nishiguchi, M. K.

2009-01-01

247

Plant treatment, pollutant load, and soil type effects in rhizosphere ecology of trace element polluted soils.  

PubMed

Re-vegetation of trace element contaminated soils can alter the pH and chelating capacity in the rhizosphere, increasing the mobility of pollutants, which, in turn, may impact on rhizosphere ecology. In this study a short-term pot experiment was carried out in order to investigate the multi-factorial effects of: buffering capacity (sandy-loam and loam soils); pollutant load (0%, 1.3%, and 4% of pyrite sludge), and the presence/absence of plant (Lolium perenne L. and Medicago sativa L.) on the mobility of trace elements, soil biochemical functionality (hydrolase activities), and biological diversity (bacterial and nematode communities). The experiment was carried out with representative soils from the Guadiamar basin (SW Spain), an area where the Aznalcóllar mining spill affected over 4000ha. Results indicated that the development of rhizospheres in polluted soils (coarse-textured) increases the mobilization of trace elements. In general the presence of roots has stimulatory effects on soil quality indicators such as hydrolase activities and both bacterial and nematode communities. However, the presence of high amount of metals interferes with these beneficial effects. This study provided evidence about the complexity of the impact of growing plants on trace element polluted soils. Trace element mobilization, hydrolase activities and bacterial and nematode communities in the rhizosphere are dependent on plant species, soil type, and pollution dose. PMID:20385407

Belén Hinojosa, M; Carreira, José A; García-Ruíz, Roberto; Rodríguez-Maroto, José M; Daniell, Tim J; Griffiths, Bryan S

2010-04-10

248

GENERIC ECOLOGICAL ASSESSMENT ENDPOINTS (GEAE) FOR ECOLOGICAL RISK ASSESSMENT  

EPA Science Inventory

Ecological risk assessment is a process for evaluating the likelihood that adverse ecological effects may occur or are occurring as a result of exposure to one or more stressors. A critical early step in conducting an ecological risk assessment is to select assessment endpoints. ...

249

Studying pretrial publicity effects: new methods for improving ecological validity and testing external validity.  

PubMed

Although research examining the effects of pretrial publicity (PTP) on individuals' appraisals of a defendant and verdict decision making generally has been found to be internally valid, the external validity has been questioned by some social scientists as well as lawyers and judges. It is often proposed that the verisimilitude (or ecological validity) ofthe research should be increased in the service of increasing external validity; however, increasing verisimilitude can be costly in terms of both time and money. It is proposed that the Internet is a viable means of conducting PTP research that allows high verisimilitude without high costs. This is demonstrated with a study in which we used the Internet to examine PTP effects in an actual trial as it was taking place. Successful use of the Internet to conduct experimental research in other areas of psychology and law is discussed, as well as the importance of future research examining whether independent variables interact with methods in ways that undermine the generalizability of research findings. PMID:11868618

Studebaker, Christina A; Robbennolt, Jennifer K; Penrod, Steven D; Pathak-Sharma, Maithilee K; Groscup, Jennifer L; Devenport, Jennifer L

2002-02-01

250

Habitat differentiation and the ecological costs of hybridization: the effects of introduced mulberry (Morus alba) on a native congener (M. rubra)  

Microsoft Academic Search

Summary 1 The effects of hybridization on the abundance of parental taxa depends on their relative frequency, the viability of hybrid offspring and the degree of ecological differ- entiation among parental and hybrid taxa. Habitat overlap can facilitate competition for suitable sites and threaten the persistence of parental taxa, especially those in small populations. 2 Here we examine ecological differentiation

KEVIN S. BURGESS; BRIAN C. HUSBAND

2006-01-01

251

Microbiology of Sewage Lagoons - Effects of Industrial Wastes on Lagoon Ecology.  

National Technical Information Service (NTIS)

The report presents some of the ecologic changes occurring in sewage lagoons receiving domestic wastes plus potato processing wastes (Grafton), cheese manufacturing wastes (Lakota), and domestic wastes (Harvey). Since each lagoon presents unique operating...

J. W. Vennes H. W. Holm M. W. Wentz K. L. Hanson J. M. Granum

1969-01-01

252

Ecological and toxicological effects of inorganic nitrogen pollution in aquatic ecosystems: A global assessment.  

PubMed

We provide a global assessment, with detailed multi-scale data, of the ecological and toxicological effects generated by inorganic nitrogen pollution in aquatic ecosystems. Our synthesis of the published scientific literature shows three major environmental problems: (1) it can increase the concentration of hydrogen ions in freshwater ecosystems without much acid-neutralizing capacity, resulting in acidification of those systems; (2) it can stimulate or enhance the development, maintenance and proliferation of primary producers, resulting in eutrophication of aquatic ecosystems; (3) it can reach toxic levels that impair the ability of aquatic animals to survive, grow and reproduce. Inorganic nitrogen pollution of ground and surface waters can also induce adverse effects on human health and economy. Because reductions in SO2 emissions have reduced the atmospheric deposition of H2SO4 across large portions of North America and Europe, while emissions of NOx have gone unchecked, HNO3 is now playing an increasing role in the acidification of freshwater ecosystems. This acidification process has caused several adverse effects on primary and secondary producers, with significant biotic impoverishments, particularly concerning invertebrates and fishes, in many atmospherically acidified lakes and streams. The cultural eutrophication of freshwater, estuarine, and coastal marine ecosystems can cause ecological and toxicological effects that are either directly or indirectly related to the proliferation of primary producers. Extensive kills of both invertebrates and fishes are probably the most dramatic manifestation of hypoxia (or anoxia) in eutrophic and hypereutrophic aquatic ecosystems with low water turnover rates. The decline in dissolved oxygen concentrations can also promote the formation of reduced compounds, such as hydrogen sulphide, resulting in higher adverse (toxic) effects on aquatic animals. Additionally, the occurrence of toxic algae can significantly contribute to the extensive kills of aquatic animals. Cyanobacteria, dinoflagellates and diatoms appear to be major responsible that may be stimulated by inorganic nitrogen pollution. Among the different inorganic nitrogenous compounds (NH4+, NH3, NO2-, HNO2NO3-) that aquatic animals can take up directly from the ambient water, unionized ammonia is the most toxic, while ammonium and nitrate ions are the least toxic. In general, seawater animals seem to be more tolerant to the toxicity of inorganic nitrogenous compounds than freshwater animals, probably because of the ameliorating effect of water salinity (sodium, chloride, calcium and other ions) on the tolerance of aquatic animals. Ingested nitrites and nitrates from polluted drinking waters can induce methemoglobinemia in humans, particularly in young infants, by blocking the oxygen-carrying capacity of hemoglobin. Ingested nitrites and nitrates also have a potential role in developing cancers of the digestive tract through their contribution to the formation of nitrosamines. In addition, some scientific evidences suggest that ingested nitrites and nitrates might result in mutagenicity, teratogenicity and birth defects, contribute to the risks of non-Hodgkin's lymphoma and bladder and ovarian cancers, play a role in the etiology of insulin-dependent diabetes mellitus and in the development of thyroid hypertrophy, or cause spontaneous abortions and respiratory tract infections. Indirect health hazards can occur as a consequence of algal toxins, causing nausea, vomiting, diarrhoea, pneumonia, gastroenteritis, hepatoenteritis, muscular cramps, and several poisoning syndromes (paralytic shellfish poisoning, neurotoxic shellfish poisoning, amnesic shellfish poisoning). Other indirect health hazards can also come from the potential relationship between inorganic nitrogen pollution and human infectious diseases (malaria, cholera). Human sickness and death, extensive kills of aquatic animals, and other negative effects, can have elevated costs on human economy, with the recreation and tourism industry suffering the most impo

Camargo, Julio A; Alonso, Alvaro

2006-06-16

253

Evolution of asynchronous motor activity in paired muscles: effects of ecology, morphology, and phylogeny.  

PubMed

Many studies of feeding behavior have implanted electrodes unilaterally (in muscles on only one side of the head) to determine the basic motor patterns of muscles controlling the jaws. However, bilateral implantation has the potential to achieve a more comprehensive understanding of modification of the motor activity that may be occurring between the left and right sides of the head. In particular, complex processing of prey is often characterized by bilaterally asynchronous and even unilateral activation of the jaw musculature. In this study, we bilaterally implant feeding muscles in species from four orders of elasmobranchs (Squaliformes, Orectolobiformes, Carcharhiniformes, Rajoidea) in order to characterize the effects of type of prey, feeding behavior, and phylogeny on the degree of asynchronous muscle activation. Electrodes were implanted in three of the jaw adductors, two divisions of the quadratomandibularis and the preorbitalis, as well as in a cranial elevator in sharks, the epaxialis. The asynchrony of feeding events (measured as the degree to which activity of members of a muscle pair is out of phase) was compared across species for capture versus processing and simple versus complex prey, then interpreted in the contexts of phylogeny, morphology, and ecology to clarify determinants of asynchronous activity. Whereas capture and processing of prey were characterized by statistically similar degrees of asynchrony for data pooled across species, events involving complex prey were more asynchronous than were those involving simple prey. The two trophic generalists, Squalus acanthias and Leucoraja erinacea, modulated the degree of asynchrony according to type of prey, whereas the two behavioral specialists, Chiloscyllium plagiosum and Mustelus canis, activated the cranial muscles synchronously regardless of type of prey. These differences in jaw muscle activity would not have been detected with unilateral implantation. Therefore, we advocate bilateral implantation in studies of cranial muscle function in fishes, particularly when investigating behaviors associated with processing complex prey. Incorporating this methodology will provide a more detailed understanding of the coordination and evolution of paired-muscle function in the feeding apparatus relative to behavioral and ecological performance. PMID:21669790

Gerry, Shannon P; Ramsay, Jason B; Dean, Mason N; Wilga, Cheryl D

2008-06-09

254

Effect of hypoxia and anoxia on invertebrate behaviour: ecological perspectives from species to community level  

NASA Astrophysics Data System (ADS)

Coastal hypoxia and anoxia have become a global key stressor to marine ecosystems, with almost 500 dead zones recorded wordwide. By triggering cascading effects from the individual organism to the community and ecosystem-level, oxygen depletions threat marine biodiversity and can alter ecosystem structure and function. By integrating both physiological function and ecological processes, animal behaviour is ideal for assessing the stress state of benthic macrofauna to low dissolved oxygen. The initial response of organisms can serve as an early-warning signal, while the successive behavioural reactions of key species indicate hypoxia levels and help assess community degradation. Here we document the behavioural responses of a representative spectrum of benthic macrofauna in the natural setting in the Northern Adriatic Sea, Mediterranean. We experimentally induced small-scale anoxia with a benthic chamber in 24 m depth to overcome the difficulties in predicting the onset of hypoxia, which often hinders full documentation in the field. The behavioural reactions were documented with a time-lapse camera. Oxygen depletion elicited significant and repeatable changes in general (visibility, locomotion, body movement and posture, location) and species-specific reactions in virtually all organisms (302 individuals from 32 species and 2 species groups). Most atypical (stress) behaviours were associated with specific oxygen thresholds: arm-tipping in the ophiuroid Ophiothrix quinquemaculata, for example, with the onset of mild hypoxia (< 2 mL O2 L-1), the emergence of polychates on the sediment surface with moderate hypoxia (< 1 mL O2 L-1), the emergence of the infaunal sea urchin Schizaster canaliferus on the sediment with severe hypoxia (< 0.5 mL O2 L-1) and heavy body rotations in sea anemones with anoxia. Other species changed their activity patterns, i.e. circadian rhythm in the hermit crab Paguristes eremita or the bioherm-associated crab Pisidia longimana. Intra- and interspecific reactions were weakened or changed: decapods ceased defensive and territorial behaviour, and predator-prey interactions and relationships shifted. This nuanced scale of resolution is a useful tool to interpret present benthic community status (behaviour) and past mortalities (community composition, e.g. survival of tolerant species). This information on the sensitivity (onset of stress response), tolerance (mortality, survival), and characteristics (i.e. life habit, functional role) of key species also helps predict potential future changes in benthic structure and ecosystem functioning. This integrated approach can transport complex ecological processes to the public and decision-makers and help define specific monitoring, assessment and conservation plans.

Riedel, B.; Pados, T.; Pretterebner, K.; Schiemer, L.; Steckbauer, A.; Haselmair, A.; Zuschin, M.; Stachowitsch, M.

2013-08-01

255

Ecological effects of contaminants in McCoy Branch, 1991--1993  

SciTech Connect

The 1984 Hazardous and Solid Waste Amendments to the Resource Conservation and Recovery Act (RCRA) required assessment of all current and former solid waste management units. Following guidelines under RCRA and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), a remedial investigation (RI) was required of the Y-12 Plant for their filled coal ash pond (FCAP) and associated areas on McCoy Branch. The RI process was initiated and assessments were presented. Because the disposal of coal ash in the ash pond, McCoy Branch, and Rogers Quarry was not consistent with the Tennessee Water Quality Act, several remediation steps were implemented between 1986 and 1994 for McCoy Branch to address disposal problems. The required ecological risk assessments of McCoy Branch watershed included provisions for biological monitoring of the watershed. The objectives of the biological monitoring were to (1) document changes in biological quality of McCoy Branch after completion of a pipeline bypassing upper McCoy Branch and further, after termination of all discharges to Rogers Quarry, (2) provide guidance on the need for additional remediation, and (3) evaluate the effectiveness of implemented remedial actions. The data from the biological monitoring program may also determine whether the goals of protection of human health and the environment of McCoy Branch are being accomplished.

Ryon, M.G. [ed.] [ed.

1996-09-01

256

Feeding habits and trophic ecology of Dasyatis longa (Elasmobranchii: Myliobatiformes): sexual, temporal and ontogenetic effects.  

PubMed

Sexual, ontogenic and temporal effects in the diet of Dasyatis longa were evaluated to determine feeding habits and trophic ecology. Numeric indices and the index of relative importance were applied to establish the feeding strategy of the species. Independence of the diet with respect to sex, dry or rainy season and size was evaluated with contingency tables, correspondence analysis and multivariate analysis (MANOVA). The trophic relationships of D. longa (by sex and size intervals) were determined using Levin's niche breadth index and the Pianka's diet overlap index and their significance was determined by null models. The trophic level for each size interval and the species was also calculated. Dasyatis longa showed a narrow niche breadth feeding mainly on shrimps and fishes and its diet was dependent on size, but not on sex or season. Juvenile individuals (class I) fed on shrimps, sub-adults (class II) on fishes and adults (class III) on stomatopods. Significant overlaps between size classes I and II and classes II and III were found. The trophic level shows D. longa to be a secondary or tertiary consumer. Due to considerable fishing pressures on shrimps, the principal prey of D. longa, it will be important to determine their ability to adapt to changes in prey populations. PMID:22497397

López-García, J; Navia, A F; Mejía-Falla, P A; Rubio, E A

2012-04-01

257

Significance and effect of ecological rehabilitation project in inland river basins in northwest China.  

PubMed

The Ecological Water Transfer and Rehabilitation Project in the arid inland area of northwest China is an important measure in restoring a deteriorated ecosystem. However, the sustainability of the project is affected by many socio-economic factors. This article examines the attitudes of the local populace toward the project, its impact on the livelihood of the people, and the positive effects of water-efficient agricultural practices in Ejina County. Related data were collected through questionnaire surveys and group discussions. The results identified three critical issues that may influence the sustainability of the project in the study area. The first issue relates to the impact of the project on the livelihood of local herdsmen. The potential for the sustainability of the project is compromised because the livelihood of the herdsmen greatly depends on the compensation awarded by the project. The second issue is that the project did not raise the water resource utilization ratio, which may undermine its final purpose. Finally, the compensation provided by the project considers losses in agriculture, but neglects the externalities and public benefit of eco-water. Thus, appropriate compensation mechanisms should be established and adopted according to local economic, environmental, and social conditions. Some recommendations for improving the sustainability of the project are provided based on the results of this study. PMID:23716005

Wang, Yu; Feng, Qi; Chen, Lijuan; Yu, Tengfei

2013-05-29

258

Effects of a Systemic Antibiotic on Nasal Bacterial Ecology in Man  

PubMed Central

The nasal flora of coagulase-positive staphylococcus carriers and noncarriers was studied in aerobic conditions in 17 individuals. Five hundred milligrams of cephalexin was given orally four times daily for 12 days, and its effects on the nasal bacteria were determined quantitatively before, during, and after treatment. The total count obtained before the drug treatment was 5.4 × 106 in carriers and 3.9 × 106 in noncarriers. The lowest total count observed was 3 days after the cessation of the drug. The increase in gram-negative rods was seen 9 days after antibiotic therapy, not during the greatest reduction of gram-positive bacteria. Coagulase-positive cocci and diphtheroids were most sensitive to drug treatment. After 36 days, the total count was restored to pretreatment level. Diphtheroids did not return to the original number and were replaced by a corresponding increase of resistant coagulase-negative cocci. An inverse relationship between coagulase-negative cocci and lipophilic diphtheroids was seen in the anterior nares of many individuals. No gross difference in nasal ecology to differentiate carriers from noncarriers was seen.

Aly, Raza; Maibach, Howard I.; Strauss, Walter G.; Shinefield, Henry R.

1970-01-01

259

Ecological effects of the insecticide imidacloprid and a pollutant from antidandruff shampoo in experimental rice fields.  

PubMed

Ecological changes caused by the insecticide imidacloprid and a pollutant from antidandruff shampoos (zinc pyrithione) were monitored in experimental paddies throughout a cultivation period. A total of 88 species were observed, with 54 of them aquatic. Plankton, nekton, benthic, and terrestrial communities from imidacloprid fields had significantly less abundance of organisms compared with control and shampoo-treated fields, either for the entire period or during early stages. The absence of Chironomus yoshimatsui and typical paddy ostracods from imidacloprid fields was most remarkable; as a consequence, green algae blooms (Spirogyra sp.) developed, which in turn hampered the establishment of weeds. Such changes occurred while residues of imidacloprid in water were present at levels greater than 1 microg/L. The overall diversity was similar in all fields and increased constantly until the end of the study. Phytophagous insects dominated in early communities, gradually giving way to predators and scavengers during late stages, but imidacloprid fields had a lower proportion of the latter trophic group. Multivariate analyses helped to describe and differentiate the communities between treatments and control. Hazard- and risk-assessment methods overestimated the effects of zinc pyrithione but failed to predict imidacloprid impacts, probably because of deficiencies in the exposure and relevant toxicity data used. PMID:16764489

Sanchez-Bayo, Francisco; Goka, Kouichi

2006-06-01

260

[Using chlorella and effective microorganisms to optimize aquatic ecological structure and to regulate water quality].  

PubMed

To optimize aquatic ecological structure and to regulate water quality, Chlorella vulgaris and effective microorganism were added to Exopalaemon carinicauda pond and fishponds. The results showed that after adding Chlorella vulgaris to the shrimp pond and fishpond, Chlorella vulgaris turned into a dominant species, and its amount was 16.92 and 4.76 times of CK. The zooplankton biomass reached to 4.32 mg.L-1 and 2.84 mg.L-1, increasing by 19.3% and 2.5%, compared with CK, respectively. Rhodospirillaceae, photosynthetic bacteria and yeast saccharomycete in the ponds could obviously change the composition, number, ratio, and biomass of the plankton (phytoplankton and zooplankton), and adjust aquatic chemical environment. The treatment of "Saccharomycete + Nitrifying bacteria" decreased the concentrations of NH4+ obviously, which was only 44% of CK. The BOD and COD in shrimp ponds were only 56.5% and 38.4% of CK. The treatment could increase the dissolved oxygen and primary production in the pond. PMID:12722449

Han, Shiqun; Zhang, Zhenhua; Yu, Lijun

2003-01-01

261

Some effects of giant Andean stem-rosettes on ground microclimate, and their ecological significance  

NASA Astrophysics Data System (ADS)

The effect of giant Andean stem-rosettes ( Coespeletia lutescens) on air and soil temperatures was studied in the Páramo de Piedras Blancas (Venezuela) at 4265 and 4385 m altitude during the dry season, which is the coldest season in this tropical mountain area. Maximum air temperatures beneath a plant canopy were only slightly higher than in the open. Minimum temperatures below the stem-rosettes were 4.7° to 7.0°C higher than in the open. This substantially reduced the intensity of nightly freezing. Soil temperature minima at 20 cm depth were 2.4° to 4.2°C higher below plants, but maxima were somewhat lower than in bare soil. These microclimatic alterations are ecologically significant for stemprosette seedlings, which should have a higher probability of survival due to the reduced frequency of frost and needle ice formation below large plants. Warmer soils at night should also result in greater water uptake by seedlings during the early morning hours, thus reducing dry-season mortality.

Pérez, Francisco L.

1989-06-01

262

Sublethal effects and predator-prey interactions: implications for ecological risk assessment.  

PubMed

Ecological risk assessments tend to focus on contaminant effects on single species in isolation. However, additional effects from interactions between species (e.g., predator-prey interactions) may also occur in natural systems. The present study investigated the consequences of sublethal contaminant effects in prey on predator-prey interactions, particularly the interaction between prey behavioral changes and predation by predators with different hunting strategies. Ambush (Ischnura elegans Vander Linden [Insecta, Odonata]) and active (Notonecta glauca Linnaeus [Insecta, Heteroptera]) predator species were used in conjunction with three prey species (Asellus aquaticus Linnaeus [Crustacea, Isopoda], Cloion dipterum Linnaeus [Insecta, Ephemeroptera], and Chironomus riparius Meigen [Insecta, Diptera]). Immobilized prey demonstrated the importance of prey behavior for determining predation rates for both single- and multiple-prey species. Chironomus riparius was less responsive following exposure to cadmium, becoming more vulnerableto attack by the active but not the ambush predator. Some evidence was also observed for reduced general activity in C. dipterum following cadmium exposure. Sublethal exposure of prey did not affect the prey choice of active predators, possibly because of prey behavioral changes being insufficient to influence their relative availabilities. However, cadmium exposure of prey did alter their susceptibility to ambush predators. There was a reduced proportion of C. dipterum and an increased proportion of A. aquaticus in the diet of ambush predators, possibly because of reduced activity in C. dipterum affecting their relative encounter rates with predators. Sublethal exposures can therefore result in reduced prey survival that would not be predicted by single-species toxicity tests. PMID:19572771

Brooks, Amy C; Gaskell, Paul N; Maltby, Lorraine L

2009-11-01

263

Salinity and temperature effects on physiological responses of Vibrio fischeri from diverse ecological niches.  

PubMed

Vibrio fischeri is a bioluminescent bacterial symbiont of sepiolid squids (Cephalopoda: Sepiolidae) and monocentrid fishes (Actinopterygii: Monocentridae). V. fischeri exhibit competitive dominance within the allopatrically distributed squid genus Euprymna, which have led to the evolution of V. fischeri host specialists. In contrast, the host genus Sepiola contains sympatric species that is thought to have given rise to V. fischeri that have evolved as host generalists. Given that these ecological lifestyles may have a direct effect upon the growth spectrum and survival limits in contrasting environments, optimal growth ranges were obtained for numerous V. fischeri isolates from both free-living and host environments. Upper and lower limits of growth were observed in sodium chloride concentrations ranging from 0.0% to 9.0%. Sepiola symbiotic isolates possessed the least variation in growth throughout the entire salinity gradient, whereas isolates from Euprymna were the least uniform at <2.0% NaCl. V. fischeri fish symbionts (CG101 and MJ101) and all free-living strains were the most dissimilar at >5.0% NaCl. Growth kinetics of symbiotic V. fischeri strains were also measured under a range of salinity and temperature combinations. Symbiotic V. fischeri ES114 and ET101 exhibited a synergistic effect for salinity and temperature, where significant differences in growth rates due to salinity existed only at low temperatures. Thus, abiotic factors such as temperature and salinity have differential effects between free-living and symbiotic strains of V. fischeri, which may alter colonization efficiency prior to infection. PMID:18587609

Soto, W; Gutierrez, J; Remmenga, M D; Nishiguchi, M K

2008-06-28

264

General Ecology  

NSDL National Science Digital Library

This tutorial explains how environmental conditions and organism interactions determine animal and tree distribution and abundance. There are definitions of important ecological terms such as ecology, interactions, and abundance; descriptions of the environmental conditions needed for rainforests and how they provide habitat for many species; and an explanation of the spawning process. The tutorial also introduces food chain concepts and the unique ecology of riparian habitats. A quiz is also available.

265

The Influence of Hitchhiking and Deleterious Mutation Upon Asexual Mutation Rates  

PubMed Central

The question of how natural selection affects asexual mutation rates has been considered since the 1930s, yet our understanding continues to deepen. The distribution of mutation rates observed in natural bacteria remains unexplained. It is well known that environmental constancy can favor minimal mutation rates. In contrast, environmental fluctuation (e.g., at period T) can create indirect selective pressure for stronger mutators: genes modifying mutation rate may “hitchhike” to greater frequency along with environmentally favored mutations they produce. This article extends a well-known model of Leigh to consider fitness genes with multiple mutable sites (call the number of such sites ?). The phenotypic effect of such a gene is enabled if all sites are in a certain state and disabled otherwise. The effects of multiple deleterious loci are also included (call the number of such loci ?). The analysis calculates the indirect selective effects experienced by a gene inducing various mutation rates for given values of ?, ?, and T. Finite-population simulations validate these results and let us examine the interaction of drift with hitchhiking selection. We close by commenting on the importance of other factors, such as spatiotemporal variation, and on the origin of variation in mutation rates.

Palmer, Michael E.; Lipsitch, Marc

2006-01-01

266

Magnitude and sign epistasis among deleterious mutations in a positive-sense plant RNA virus  

PubMed Central

How epistatic interactions between mutations determine the genetic architecture of fitness is of central importance in evolution. The study of epistasis is particularly interesting for RNA viruses because of their genomic compactness, lack of genetic redundancy, and apparent low complexity. Moreover, interactions between mutations in viral genomes determine traits such as resistance to antiviral drugs, virulence and host range. In this study we generated 53 Tobacco etch potyvirus genotypes carrying pairs of single-nucleotide substitutions and measured their separated and combined deleterious fitness effects. We found that up to 38% of pairs had significant epistasis for fitness, including both positive and negative deviations from the null hypothesis of multiplicative effects. Interestingly, the sign of epistasis was correlated with viral protein–protein interactions in a model network, being predominantly positive between linked pairs of proteins and negative between unlinked ones. Furthermore, 55% of significant interactions were cases of reciprocal sign epistasis (RSE), indicating that adaptive landscapes for RNA viruses maybe highly rugged. Finally, we found that the magnitude of epistasis correlated negatively with the average effect of mutations. Overall, our results are in good agreement to those previously reported for other viruses and further consolidate the view that positive epistasis is the norm for small and compact genomes that lack genetic robustness.

Lalic, J; Elena, S F

2012-01-01

267

ECOLOGICAL RISK ASSESSMENT WORKSHOP  

EPA Science Inventory

As ecological risk assessment evolves, it is moving beyond focus on single species toward addressing multiple species and their interactions, and from assessing effects of simple chemical toxicity to the cumulative impacts of multiple interacting chemical, physical, and biologica...

268

ECOLOGICAL FORECASTING FOR WATERSHEDS  

EPA Science Inventory

To effectively manage watersheds, the assessment of watershed ecological response to physicochemical stressors such as nutrients, sediments, pathogens, and toxics over broad spatial and temporal scales is needed. Assessments at this level of complexity requires the development of...

269

[Ecological effect of recirculated landfill leachate with different hydraulic loading on plant-soil system].  

PubMed

The ecological effect of irrigating recirculated leachate with different hydraulic loading on bermudagrass (Cynodon dactylon) and soil system was evaluated. The results show that leachate irrigation with hydraulic loading of 2.77-12.00 mm d(-1) leads to high chlorophyll content, low proline (Pro) content, as well as low malondialdehyde (MDA) and H2O2 content. Soil enzyme activities, respirations, microbial biomass and ratio of biomass carbon to organic carbon (Cmic/Corg) are rather higher. Among leachte irrigation group, leachate irrigation with hydraulic loading of 6.46-10.15 mm x d(-1) leads to declined proline, increased chlorophyll content, low POD activity and low content of MDA and H2O2. Soil bio-activity related parameters, such as soil enzyme activities, respirations, microbial biomass and Cmic/Corg are all enhanced at 6.46-10.15 mm x d(-1) of hydraulic loading. However, when hydraulic loading increases to 12.00 mm x d(-1) or declines to 2.77-4.16 mm x d(-1), the stress of irrigation on bermudagrass is aggravated, and soil bioactivity declines. The results reveal that leachate irrigation could alleviate the stress of environment on bermudagrass and improve the bio-activity of soil. The positive effect of leachate irrigation on the plant-soil system might be contributed to changes of soil water and physico-chemical property after leachate irrigated to the soil. The experimental results suggest that leachate irrigation could benefit plant-soil system, especially when controlled at suitable hydraulic loading. PMID:16850839

Wang, Ru-yi; He, Pin-jing; Shao, Li-ming; Yuan, Li; Li, Guo-jian

2006-05-01

270

Ecological energetics of the desert tortoise (Gopherus Agassizii): Effects of rainfall and drought  

SciTech Connect

To elucidate ecological effects of variation in the temporal distribution of a limiting resource (water in the Mojave Desert), energetics of two free-living populations of desert tortoises (Gopherus [=Xerobates] agassizii) were studied concurrently over 18 mo with use of doubly-labeled water. Field metabolic rates (FMR) and feeding rates were highly variable. This variability was manifested at several levels, including seasonal changes within populations, year-to-year differences within populations, and differences between populations. Underlying observed patterns and contrasts was considerable variation among individuals. Much of the variation in energetic variables was associated with a single climatic variable, rainfall. Seasonal, annual, and interpopulation differences in FMR and foraging rates corresponded to differences in availability of free-standing water from rainstorms. Some differences among individuals were apparently due to differences in proclivity or ability to drink. Tortoises had very low FMRs relative to other reptiles, allowed them to tolerate long periods of chronic energy shortage during a drought. Calculations suggested that tortoises experienced a net loss of energy shortage during a drought and tortoises experienced a net loss of energy on their spring diet of succulent annual plants. If so, tortoises require drier forage to accrue an energy profit, emphasizing reliance on drinking rainwater. Further, it suggests that growth (as protein deposition) and net acquisition of energy may be temporally decoupled in desert tortoises, with potential consequences for geographic variation in life history. Energy acquisition and expenditure in desert tortoises are strongly constrained by the contingencies of rainfall, both indirectly through effects on availability and quality of food, and directly through reliance on free-standing water for drinking, which is apparently necessary for achieving a net annual energy profit. 61 refs., 5 figs., 5 tabs.

Peterson, C.C. [Univ. of California, Los Angeles, CA (United States)

1996-09-01

271

Effect of nationwide injury prevention programme on serious spinal injuries in New Zealand rugby union: ecological study  

Microsoft Academic Search

Objective To investigate the effect of RugbySmart, a nationwide educational injury prevention programme, on the frequency of spinal cord injuries.Design Ecological study.Setting New Zealand rugby union. Participants Population at risk of injury comprised all New Zealand rugby union players. Intervention From 2001, all New Zealand rugby coaches and referees have been required to complete RugbySmart, which focuses on educating rugby

Kenneth L Quarrie; Simon M Gianotti; Will G Hopkins; Patria A Hume

2007-01-01

272

Fermented and nonfermented liquid feed to growing pigs: Effect on aspects of gastrointestinal ecology and growth performance  

Microsoft Academic Search

The effect of feeding dry feed (DF), non- fermented liquid feed (NFLF), and fermented liquid feed(FLF)togrowingpigsonaspectsofgastrointestinal ecology and on performance was investigated. Nonfer- mented liquid feed was prepared by mixing feed and water at a ratio of 1:2.5 immediately before feeding. Fermented liquid feed was prepared by mixing feed and water in the same ratio as NFLF, and stored in

N. Canibe; B. B. Jensen

2010-01-01

273

Disentangling the effects of geographic and ecological isolation on genetic differentiation.  

PubMed

Populations can be genetically isolated both by geographic distance and by differences in their ecology or environment that decrease the rate of successful migration. Empirical studies often seek to investigate the relationship between genetic differentiation and some ecological variable(s) while accounting for geographic distance, but common approaches to this problem (such as the partial Mantel test) have a number of drawbacks. In this article, we present a Bayesian method that enables users to quantify the relative contributions of geographic distance and ecological distance to genetic differentiation between sampled populations or individuals. We model the allele frequencies in a set of populations at a set of unlinked loci as spatially correlated Gaussian processes, in which the covariance structure is a decreasing function of both geographic and ecological distance. Parameters of the model are estimated using a Markov chain Monte Carlo algorithm. We call this method Bayesian Estimation of Differentiation in Alleles by Spatial Structure and Local Ecology (BEDASSLE), and have implemented it in a user-friendly format in the statistical platform R. We demonstrate its utility with a simulation study and empirical applications to human and teosinte data sets. PMID:24102455

Bradburd, Gideon S; Ralph, Peter L; Coop, Graham M

2013-07-24

274

Soil Ecology  

NASA Astrophysics Data System (ADS)

Soil Ecology is designed to meet the increasing challenge faced by today's environmental scientists, ecologists, agriculturalists, and biotechnologists for an integrated approach to soil ecology. It emphasizes the interrelations among plants, animals, and microbes, by first establishing the fundamental physical and chemical properties of the soil habitat and then functionally characterizing the major components of the soil biota and some of their most important interactions. The fundamental principles underpinning soil ecology are established and this then enables an integrated approach to explore and understand the processes of soil nutrient (carbon, nitrogen, and phosphorus) cycling and the ecology of extreme soil conditions such as soil-water stress. Two of the most topical aspects of applied soil ecology are then selected. First, the ecology of soil pollution is examined, focusing on acid deposition and radionuclide pollution. Second, manipulation of soil ecology through biotechnology is discussed, illustrating the use of pesticides and microbial inocula in soils and pointing toward the future by considering the impact of genetically modified inocula on soil ecology.

Killham, Ken

1994-04-01

275

Ecological Consultancy  

ERIC Educational Resources Information Center

|This is the first of a new regular feature on careers, designed to provide those who teach biology with some inspiration when advising their students. In this issue, two consultant ecologists explain how their career paths developed. It is a misconception that there are few jobs in ecology. Over the past 20 or 30 years ecological consultancy has…

Wilson, Scott McG.; Tattersfield, Peter

2004-01-01

276

GROWTH RESPONSE OF WEED AND CROP SEEDLINGS TO DELETERIOUS RHIZOBACTERIA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Selected bacterial isolates previously demonstrated to be suppressive toward weed species in the laboratory were tested for effectiveness under greenhouse conditions. Rhizobacteria varied in ability to inhibit growth of host or other weed species. Some bacterial isolates caused up to 75% growth in...

277

The ecological effects of thermopeaking in Alpine streams in flume simulations  

NASA Astrophysics Data System (ADS)

In Alpine areas, the temporal patterns of hydropower plants operations can have consequences for the water bodies which receive downstream releases in the form of "hydropeaking", typically consisting in sharp releases of turbinated water in the river reaches below dams. Hydropeaking may significantly affect also the thermal regime of rivers: typically power plants fed by hypolimnetic releases from large dams cause a reduction in summer temperature and an increase in winter temperatures for long distances downstream. Very few studies have addressed the effects of the short-term temperature fluctuations related to hydropeaking (i.e., thermopeaking) on aquatic fauna, although they can be a major cause of riverine habitat degradation posing serious threats to aquatic communities. In the Adige River watershed, warm thermopeaking occurs from September to January and results in additional (up to 4°C) heating to the natural dial fluctuations; cold thermopeaking occurs from March to July and cools down the temperature (up to 6°C), in contrast with the natural trend that would result in heating during the day. The biological effects of thermopeaking are difficult to study in nature, because they are associated with hydropeaking, which is known to cause a high catastrophic drift due to the increased intensity of bed scour. However, controlled simulations of thermopeaking events could be performed in artificial flumes. We used artificial flumes which had proved to perform discharge manipulations which simulate hydropeaking events, and conducted four simulations, two warm thermopeakings in early and late winter, and two cold-thermopeakings, in early and late summer, respectively. The impact of thermopeaking on benthic macroinvertebrates was assessed by collecting those organisms which are displaced from the substrate and drift in the water column. Displacement can be active (i.e., part of the behavioural repertoire of certain insect species), or passive (i.e., catastrophic and generated by any disturbance). Drifting invertebrates were collected at time intervals before the simulation, and at continuous, short-time intervals during the simulation in order to follow the changes in drift over a short time period during the simulation. We assessed the effects of thermopreaking on the benthos community by answering to the following questions: 1) Do thermal alterations induce an increase in drift of benthic invertebrates? 3) Do a reduction or an increase in water temperature have different effects of invertebrate drift? Benthic invertebrates responded more to the cold thermopeaking simulations, with differences among taxa with different life strategies and ecological requirements.

Maiolini, Bruno; Carolli, Mauro; Bruno, M. Cristina; Siviglia, Annunziato

2010-05-01

278

Climate change effects on runoff, catchment phosphorus loading and lake ecological state, and potential adaptations.  

PubMed

Climate change may have profound effects on phosphorus (P) transport in streams and on lake eutrophication. Phosphorus loading from land to streams is expected to increase in northern temperate coastal regions due to higher winter rainfall and to a decline in warm temperate and arid climates. Model results suggest a 3.3 to 16.5% increase within the next 100 yr in the P loading of Danish streams depending on soil type and region. In lakes, higher eutrophication can be expected, reinforced by temperature-mediated higher P release from the sediment. Furthermore, a shift in fish community structure toward small and abundant plankti-benthivorous fish enhances predator control of zooplankton, resulting in higher phytoplankton biomass. Data from Danish lakes indicate increased chlorophyll a and phytoplankton biomass, higher dominance of dinophytes and cyanobacteria (most notably of nitrogen fixing forms), but lower abundance of diatoms and chrysophytes, reduced size of copepods and cladocerans, and a tendency to reduced zooplankton biomass and zooplankton:phytoplankton biomass ratio when lakes warm. Higher P concentrations are also seen in warm arid lakes despite reduced external loading due to increased evapotranspiration and reduced inflow. Therefore, the critical loading for good ecological state in lakes has to be lowered in a future warmer climate. This calls for adaptation measures, which in the northern temperate zone should include improved P cycling in agriculture, reduced loading from point sources, and (re)-establishment of wetlands and riparian buffer zones. In the arid Southern Europe, restrictions on human use of water are also needed, not least on irrigation. PMID:19704137

Jeppesen, Erik; Kronvang, Brian; Meerhoff, Mariana; Søndergaard, Martin; Hansen, Kristina M; Andersen, Hans E; Lauridsen, Torben L; Liboriussen, Lone; Beklioglu, Meryem; Ozen, Arda; Olesen, Jørgen E

2009-08-24

279

Fate and ecological effects of decabromodiphenyl ether in a field lysimeter.  

PubMed

Flame-retardant polybrominated diphenyl ethers (PBDEs) are environmental contaminants. Deca-BDE is increasingly used commercially, but little is known about the long-term fate and impact of its major component, decabromodiphenyl ether (BDE-209), on the soil environment. In this study, we investigated the fate and ecological effect of BDE-209 over 4 years in outdoor lysimeters in a field planted with a rice-wheat rotation. BDE-209 and six lower-brominated PBDEs (BDE-28, -47, -99, -153, -154, and -183) were detected in soil layers of the test lysimeter. We calculated an average BDE-209 migration rate of 1.54 mg·m(-2)·yr(-1). In samples collected in May 2008, November 2008, November 2009, November 2010, and November 2011, 95.5%, 94.3%, 108.1%, 33.8%, and 35.5% of the spiked BDE-209 were recovered, respectively. We predicted the major pathway for debromination of BDE-209 in soil to be: BDE-209?BDE-183?BDE-153/BDE-154?BDE-99?BDE-47?BDE-28. In plants, BDE-209 and seven lower-brominated PBDEs (BDE-28, -47, -99, -100, -153, -154, and -183) were detected. BDE-100 was mainly derived from the debromination of BDE-154 in plants, but sources of other lower-brominated PBDEs were still difficult to determine. In soils containing BDE-209 for 4 years, soil urease activity increased, and soil protease activity slightly decreased. Our results provide important insights for understanding the behavior of BDE-209 in agricultural soils. PMID:23899302

Du, Wenchao; Ji, Rong; Sun, Yuanyuan; Zhu, Jianguo; Wu, Jichun; Guo, Hongyan

2013-08-07

280

Calibrating biomonitors to ecological disturbance: a new technique for explaining metal effects in natural waters.  

PubMed

Bioaccumulated toxic metals in tolerant biomonitors are indicators of metal bioavailability and can be calibrated against metal-specific responses in sensitive species, thus creating a tool for defining dose-response for metals in a field setting. Dose-response curves that define metal toxicity in natural waters are rare. Demonstrating cause and effect under field conditions and integrated chemical measures of metal bioavailability from food and water is problematic. The total bioaccumulated metal concentration in any organism that is a net accumulator of the metal is informative about metal bioavailability summed across exposure routes. However, there is typically no one universal metal concentration that is indicative of toxicity, especially across species, largely because of interspecies differences in detoxification. Stressed organisms are also only present across a narrow range in the dose-response curve, limiting the use of singles species as both biomonitors and bioindicator of stress. Herein we show, in 3 field settings, that bioaccumulated Cu concentrations in a metal-tolerant, riverine biomonitor (species of the caddisfly genus Hydropsyche spp.) can be calibrated against metal-specific ecological responses across very wide ranges of contamination. Using the calibrated dose-response, we show that reduced abundance of species and individuals from particularly sensitive mayfly families (heptageniid mayflies) is more than 2-fold more sensitive to bioavailable Cu than other traditional measures of stress like EPT or total number of benthic macroinvertebrate species. We propose that this field dose-response curve be tested more widely for general application, and that calibrations against other stress responses be developed for biomonitors from lakes, estuaries, and coastal marine ecosystems. PMID:20821686

Luoma, Samuel N; Cain, Daniel J; Rainbow, Philip S

2010-04-01

281

Effects of ecological flooding on the temporal and spatial dynamics of carabid beetles (Coleoptera, Carabidae) and springtails (Collembola) in a polder habitat  

PubMed Central

Abstract Within the scope of the Integrated Rhine Program an ecological flood gate and channel was inserted into the polder “Ingelheim” to enhance animal and plant diversity. In 2008, carabid beetles and springtails were collected, using pitfall traps, to measure the effects of ecological flooding and a strong precipitation event at a flood-disturbed and a dry location in this area. At both localities, xerophilic and mesophilic carabid beetle species were dominant throughout the study period. The total number of individuals of hygrophilic species was comparatively constant, while species number increased, partly due to the changed moisture conditions caused by ecological flooding and strong precipitation. Carabid beetle diversity and evenness decreased marginally when ecological flooding was absent. Springtails represent a less mobile arthropod order, and as such the impact of ecological flooding was stronger. An increase in both numbers of species and individuals of hygrophilic and hygrotolerant species occurred in the flood-disturbed location after ecological flooding. After the sites at both locations had dried, the number of individuals belonging to these species declined rapidly. In contrast to carabid species, the strong precipitation event showed no influence on hygrophilic springtail species. Thus, collembolan diversity and evenness decreased markedly in the absence of flooding. We showed that ecological flooding has an influence on the spatial and temporal dynamics of different arthropod groups that inhabit the polder “Ingelheim”. These findings demonstrate the importance of using different arthropod groups as bioindicators in determining the ecological value of a particular polder design.

Lessel, Tanja; Marx, Michael Thomas; Eisenbeis, Gerhard

2011-01-01

282

Effect of aridification on carbon isotopic variation and ecologic evolution at 5.3 Ma in the Asian interior  

NASA Astrophysics Data System (ADS)

The Cenozoic era is marked by dramatic climatic and ecological changes. The timing of the emergence and the subsequent expansions of C4 grasses are prominent biological events on Earth. In China, thick Cenozoic deposits in the Tarim and Junggar Basins, which are located in the Asian interior, provide important geological archives for studying paleoenvironmental changes. Here we use carbon isotope compositions of organic matter to reconstruct the history of ecologic evolution during the late Cenozoic in the Tarim and Junggar Basins. The results show that there is a shift to slightly higher ?13C values at 5.3 Ma indicating a change in terrestrial ecosystems in the Asian interior driven by an increased regional aridity rather than decreasing atmospheric pCO2 levels. The weakened water vapor transportation related to the retreat of Paratethys Ocean and the enhanced rain shadow effect of mountain uplift during the latest Miocene mostly triggered this event.

Sun, Jimin; Lü, Tongyan; Gong, Yingzeng; Liu, Weiguo; Wang, Xu; Gong, Zhijun

2013-10-01

283

EXPERIMENTAL MARINE MICROCOSM TEST PROTOCOL AND SUPPORT DOCUMENT. MEASUREMENT OF THE ECOLOGICAL EFFECTS, FATE AND TRANSPORT OF CHEMICALS IN A SITE-SPECIFIC MARINE ECOSYSTEM  

EPA Science Inventory

Experimental microcosms designed to simulate major physical, chemical and biological complexities of site specific, coastal marine ecosystems are described. Procedures are presented which enable the investigator to determine the fate, ecological effects and transport for 'new' an...

284

Eco-genetic model to explore fishing-induced ecological and evolutionary effects on growth and maturation schedules  

PubMed Central

Eco-genetic individual-based models involve tracking the ecological dynamics of simulated individual organisms that are in part characterized by heritable parameters. We developed an eco-genetic individual-based model to explore ecological and evolutionary interactions of fish growth and maturation schedules. Our model is flexible and allows for exploration of the effects of heritable growth rates (based on von Bertalanffy and biphasic growth patterns), heritable maturation schedules (based on maturation reaction norm concepts), or both on individual- and population-level traits. In baseline simulations with rather simple ecological trade-offs and over a relatively short time period (<200 simulation years), simulated male and female fish evolve differential genetic growth and maturation. Further, resulting patterns of genetically determined growth and maturation are influenced by mortality rate and density-dependent processes, and maturation and growth parameters interact to mediate the evolution of one another. Subsequent to baseline simulations, we conducted experimental simulations to mimic fisheries harvest with two size-limits (targeting large or small fish), an array of fishing mortality rates, and assuming a deterministic or stochastic environment. Our results suggest that fishing with either size-limit may induce considerable changes in life-history trait expression (maturation schedules and growth rates), recruitment, and population abundance and structure. However, targeting large fish would cause more adverse genetic effects and may lead to a population less resilient to environmental stochasticity.

Wang, Hui-Yu; Hook, Tomas O

2009-01-01

285

Ecological Carrying Capacity Research: Yosemite National Park. Part I. The Effects of Human Trampling and Urine on Subalpine Vegetation, a Survey of Past and Present Backcountry Use, and the Ecological Carrying Capacity of Wilderness.  

National Technical Information Service (NTIS)

Ecological carrying capacity of wilderness for recreational use is approached through a study at Nelson Lake, elevation 2,930 m (9,600 ft), in the lodgepole-subalpine zone of Yosemite National Park, California. The effects of historical land use, human ur...

D. O. Holmes H. E. M. Dobson

1976-01-01

286

P2X7 receptors mediate deleterious renal epithelial-fibroblast cross talk.  

PubMed

Peritubular fibroblasts in the kidney are the major erythropoietin-producing cells and also contribute to renal repair following acute kidney injury (AKI). Although few fibroblasts were observed in the interstitium adjacent to damaged tubular epithelium in the early phase of AKI, the underlying mechanism by which their numbers were reduced remains unknown. In this study, we tested the hypothesis that damaged renal epithelial cells directly induce renal interstitial fibroblast death by releasing intracellular ATP and activating purinergic signaling. Exposure of a cultured rat renal interstitial fibroblast cell line (NRK-49F) to necrotic renal proximal tubular cells (RPTC) lysate or supernatant induced NRK-49F cell death by apoptosis and necrosis. Depletion of ATP with apyrase or inhibition of the P2X purinergic receptor with pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid blocked the deleterious effect of necrotic RPTC supernatant. The P2X7 receptor, an ATP-sensitive purinergic receptor, was not detected in cultured NRK-49F cells but was inducible by necrotic RPTC supernatant. Treatment with A438079, a highly selective P2X7 receptor inhibitor, or knockdown of the P2X7 receptor with small interference RNA diminished renal fibroblast death induced by necrotic RPTC supernatant. Conversely, overexpression of the P2X7 receptor potentiated this response. Collectively, these findings provide strong evidence that damaged renal epithelial cells can directly induce the death of renal interstitial fibroblasts by ATP activation of the P2X7 receptor. PMID:20861083

Ponnusamy, Murugavel; Ma, Li; Gong, Rujun; Pang, Maoyin; Chin, Y Eugene; Zhuang, Shougang

2010-09-22

287

MICROCOSMS AS TEST SYSTEMS FOR THE ECOLOGICAL EFFECTS OF TOXIC SUBSTANCES: AN APPRAISAL WITH CADMIUM  

EPA Science Inventory

A two-phase set of experiments was conducted to address some of the problems inherent in ecological screening of toxic substances in aquatic microcosms. Phase I was a 4 x 4 factorial experiment (four levels of cadmium versus four levels of nutrient enrichment) on the interactive ...

288

Effects of ecological succession on surface mineral horizons in Japanese volcanic ash soil  

Microsoft Academic Search

Japanese volcanic ash soils have very thick and dark-colored A horizons with large amounts of black humic acids which are characterized by their extremely high aromatic structure and stabilities such as black carbon. Nevertheless, the disappearance of the melanic epipedon with a decreasing aromatic C and increasing alkyl C proportion of humic acids was observed in ecological succession for only

Yasuo Iimura; Mari Fujimoto; Mitsuru Hirota; Kenji Tamura; Teruo Higashi; Koyo Yonebayashi; Nobuhide Fujitake

2010-01-01

289

ECOLOGICAL AND NONHUMAN BIOLOGICAL EFFECTS OF SOLAR UV-B RADIATION  

EPA Science Inventory

Recent studies regarding the impact of UV-B radiation upon ecological and nonhuman biological systems is the subject of the report. For years scientists and laymen alike have causally noted the impact of solar ultraviolet radiation upon the non-human component of the biosphere. S...

290

Overall effect of rice biomass and fish on the aquatic ecology of experimental rice plots  

Microsoft Academic Search

The integration of rice and fish culture promises ecologically sound and economically successful management of floodwater ecosystems. Amongst other benefits, the stocking of fish in rice fields may contribute to the soil fertility of the rice field. We investigated the impact of the rice biomass and the stocking of fish (a polyculture of Nile tilapia and common carp) on ammonium,

Nico Vromant; Nguyen Thi Hoai Chau

2005-01-01

291

A review of the ecological effects of river regulation in Australia  

Microsoft Academic Search

Responses to hydrologic change are an important theme in lotic ecology, and data for Australian rivers are accumulating in a rapid, butad hoc manner. Thia paper arranges recent contributions according to the major drainage divisions, which provide reasonably coherent environmental units. The east coastal rivers are exploited for storage, power generation and waste disposal, and Tasmanian rivers are regulated to

K. F. Walker

1985-01-01

292

Ecological Effects of an Artificial Island, Rincon Island, Punta Gorda, California.  

National Technical Information Service (NTIS)

This study documents marine ecological conditions at Rincon Island, located approximately 0.8 kilometer offshore between Ventura and Santa Barbara, California, in a depth of 14 meters. The island, which was constructed between 1957 and 1958 to serve as a ...

G. F. Johnson L. A. DeWit

1978-01-01

293

ECOLOGICAL ENDPOINT MODELING FOR TMDLS: EFFECTS OF SEDIMENT ON FISH POPULATIONS  

EPA Science Inventory

Sediment is one of the primary stressors of concern for Total Maximum Daily Loads (TMDLs) for streams, and often it is a concern because of its impact on ecological endpoints. A modeling approach relating sediment to stream fish population dynamics is presented. Equations are d...

294

Ecological and Nonhuman Biological Effects of Solar UV-B Radiation,  

National Technical Information Service (NTIS)

Recent studies regarding the impact of UV-B radiation upon ecological and nonhuman biological systems is the subject of the report. For years scientists and laymen alike have causally noted the impact of solar ultraviolet radiation upon the non-human comp...

R. C. Worrest

1984-01-01

295

Effect of ecological compensation areas on floristic and breeding bird diversity in Swiss agricultural landscapes  

Microsoft Academic Search

In the 1990s the Swiss agricultural policy was reformed and new environmental objectives were formulated. The aims of the reform were to halt the loss of agro-biodiversity and to enable the spread of endangered species. As a result, the utilised agricultural area (UAA) is now interspersed with low input ecological compensation areas (ECA), making up 13% of the UAA (extensified

F. Herzog; S. Dreier; G. Hofer; C. Marfurt; B. Schüpbach; M. Spiess; T. Walter

2005-01-01

296

[Occurrence form and ecological effect of selenium in soil and surface water of Kailuan Coalfield of Tangshan].  

PubMed

Mining induced generally adverse effect to the environmental ecosystems. This paper studied the beneficial element Se produced in the process of coal mining and burning. The occurrence form of Se in soil and surface water influx into the mine water and the enrichment of Se by crops such as wheat, maize and rice were analyzed. The results indicated that organic and residual forms are the dominant forms of Se in soil, with the soluble form accounting for only 1%. Se4+ and Se6+ accounted for 23.89% and 32.99% in total soluble Se in soil, respectively. In the surface water influx into the mine water, the percentages were 37.78% and 40.24%, respectively. The mean contents of Se in wheat, maize and rice were 0.169 mg x kg(-1), 0.094 mg x kg(-1) and 0.26 mg x kg(-1), respectively. Rice was irrigated using the mine water, which did not only solve the problem of waste water, but also produced Se-enriched rice, moreover, the contents of deleterious elements were not high. Therefore, making full use of the Se-enriched resource in the mining area would weaken the adverse effect of mining. PMID:23233966

Zhang, Xiu-Zhi; Ma, Zhong-She; Wang, Yin-Nan; Wang, Zhi-Jun; Xie, Wei-Ming

2012-10-01

297

The influence of neighborhood size and habitat shape on the accumulation of deleterious mutations.  

PubMed

To examine the impact of genetic neighborhood size and habitat shape on genetic load and the accumulation of deleterious mutation, individual-based simulations were performed in continuously distributed habitats. The risk of extinction increased as both the area of the habitat and the neighborhood size decreased. When the neighborhood area became smaller than the habitat area, habitat shape also began to influence the risk of extinction by mutation loads, expected time to extinction being shorter in longer and narrower habitats than in a square habitat. Both the number of homozygous deleterious loci per individual and the mutation load in the population increased as the neighborhood size and total population size decreased. Neighborhood size and total population size both independently affected the average number of homozygous deleterious loci per individual. In addition, as the ratio of the long to the short side of the rectangle of a habitat increased, the average number of homozygous deleterious loci increased. When the areas of the habitats were held constant, the average number of homozygous loci and the mutation loads were smallest for a regular square and largest for the longest, narrowest habitat. These results suggest that the spatial genetic structure of an individual is an important factor in the accumulation of deleterious mutations and the risk of extinction by mutation meltdown. PMID:11444951

Kawata, M

2001-08-01

298

Hsp90 is important for fecundity, longevity, and buffering of cryptic deleterious variation in wild fly populations  

PubMed Central

Background In the laboratory, the Drosophila melanogaster heat shock protein Hsp90 can buffer the phenotypic effects of genetic variation. Laboratory experiments either manipulate Hsp90 activity pharmacologically, or they induce mutations with strong effects in the gene Hsp83, the single-copy fly gene encoding Hsp90. It is unknown whether observations from such laboratory experiments are relevant in the wild. Results We here study naturally occurring mutations in Hsp83, and their effects on fitness and phenotypic buffering in flies derived from wild populations. We examined more than 4500 flies from 42 Drosophila populations distributed world-wide for insertions or deletions of mobile DNA in or near the Hsp83 gene. The insertions we observed occur at low population frequencies, and reduce Hsp83 gene expression. In competition experiments, mutant flies performed much more poorly than wild-type flies. Mutant flies were also significantly less fecund and shorter-lived than wild-type flies, as well as less well buffered against cryptic deleterious variation, as we show through inbreeding experiments. Specifically, in Hsp83 mutant flies female fecundity dropped to much lower levels after inbreeding than in wild-type flies. At even slightly elevated temperatures, inbred mutant Hsp83 populations went extinct, whereas inbred wild-type populations persisted. Conclusions Our work shows that Hsp90, a regulator of the stress response and of signaling, helps buffer deleterious variation in fruit flies derived from wild population, and that its buffering role becomes even more important under heat stress.

2012-01-01

299

DESIGNING PESTICIDE METABOLIC PATHWAY/DEGRADATE DATABASES FOR REGISTRANT SUBMITTED HEALTH EFFECTS/ECOLOGICAL EFFECTS DATA  

EPA Science Inventory

OPPTS requires information on the toxic effects of pesticide metabolites as well as the parent chemical. Currently, OPP receives metabolic maps with registrant study data submissions, but there is no efficient way to access previously submitted maps on similar chemicals to help w...

300

Marine reserves: fish life history and ecological traits matter.  

PubMed

Marine reserves are assumed to protect a wide range of species from deleterious effects stemming from exploitation. However, some species, due to their ecological characteristics, may not respond positively to protection. Very little is known about the effects of life history and ecological traits (e.g., mobility, growth, and habitat) on responses of fish species to marine reserves. Using 40 data sets from 12 European marine reserves, we show that there is significant variation in the response of different species of fish to protection and that this heterogeneity can be explained, in part, by differences in their traits. Densities of targeted size-classes of commercial species were greater in protected than unprotected areas. This effect of protection increased as the maximum body size of the targeted species increased, and it was greater for species that were not obligate schoolers. However, contrary to previous theoretical findings, even mobile species with wide home ranges benefited from protection: the effect of protection was at least as strong for mobile species as it was for sedentary ones. Noncommercial bycatch and unexploited species rarely responded to protection, and when they did (in the case of unexploited bentho-pelagic species), they exhibited the opposite response: their densities were lower inside reserves. The use of marine reserves for marine conservation and fisheries management implies that they should ensure protection for a wide range of species with different life-history and ecological traits. Our results suggest this is not the case, and instead that effects vary with economic value, body size, habitat, depth range, and schooling behavior. PMID:20437967

Claudet, J; Osenberg, C W; Domenici, P; Badalamenti, F; Milazzo, M; Falcón, J M; Bertocci, I; Benedetti-Cecchi, L; García-Charton, J A; Goñi, R; Borg, J A; Forcada, A; De Lucia, G A; Perez-Ruzafa, A; Afonso, P; Brito, A; Guala, I; Le Diréach, L; Sanchez-Jerez, P; Somerfield, P J; Planes, S

2010-04-01

301

Effects of Changes in Lugu Lake Water Quality on Schizothorax Yunnansis Ecological Habitat Based on HABITAT Model  

NASA Astrophysics Data System (ADS)

Schizothorax Yunnansis is an unique fish species only existing in Lugu Lake, which is located in the southwestern China. The simulation and research on Schizothorax Yunnansis habitat environment have a vital significance to protect this rare fish. With the development of the tourism industry, there bring more pressure on the environmental protection. The living environment of Schizothorax Yunnansis is destroyed seriously because the water quality is suffering the sustaining pollution of domestic sewage from the peripheral villages. This paper analyzes the relationship between water quality change and Schizothorax Yunnansis ecological habitat and evalutes Schizothorax Yunnansis's ecological habitat impact based on HABITAT model. The results show that when the TP concentration in Lugu Lake does not exceed Schizothorax Yunnansis's survival threshold, Schizothorax Yunnansis can get more nutrients and the suitable habitat area for itself is increased. Conversely, it can lead to TP toxicity in the Schizothorax Yunnansis and even death. Therefore, unsuitable habitat area for Schizothorax Yunnansis is increased. It can be seen from the results that HABITAT model can assist in ecological impact assessment studies by translating results of hydrological, water quality models into effects on the natural environment and human society.

Huang, Wei; Mynnet, Arthur

302

Two classes of deleterious recessive alleles in a natural population of zebrafish, Danio rerio.  

PubMed Central

Natural populations carry deleterious recessive alleles which cause inbreeding depression. We compared mortality and growth of inbred and outbred zebrafish, Danio rerio, between 6 and 48 days of age. Grandparents of the studied fish were caught in the wild. Inbred fish were generated by brother-sister mating. Mortality was 9% in outbred fish, and 42% in inbred fish, which implies at least 3.6 lethal equivalents of deleterious recessive alleles per zygote. There was no significant inbreeding depression in the growth, perhaps because the surviving inbred fish lived under less crowded conditions. In contrast to alleles that cause embryonic and early larval mortality in the same population, alleles responsible for late larval and early juvenile mortality did not result in any gross morphological abnormalities. Thus, deleterious recessive alleles that segregate in a wild zebrafish population belong to two sharply distinct classes: early-acting, morphologically overt, unconditional lethals; and later-acting, morphologically cryptic, and presumably milder alleles.

McCune, Amy R; Houle, David; McMillan, Kyle; Annable, Rebecca; Kondrashov, Alexey S

2004-01-01

303

Ecological inference  

PubMed Central

Ecological inference is the process of drawing conclusions about individual-level behavior from aggregate-level data. Recent advances involve the combination of statistical and deterministic means to produce such inferences.

Schuessler, Alexander A.

1999-01-01

304

Phytoplankton Ecology  

NSDL National Science Digital Library

This site describes phytoplankton ecology research by marine ecologists at Mote Marine Laboratory (MML), an independent, nonprofit research organization based in Sarasota, Florida. The emphasis of MML's phytoplankton ecology research is the photophysiology of marine algae -- with recent emphasis on the ability to predict and possibly mitigate blooms of the toxic marine dinoflagellate, Gymnodinium breve. The no-frills phytoplankton ecology homepage describes research and offers data (maps, figures, tables) from 1998 and 1999 projects on Red Tide transects, Nutrient and chlorophyll concentrations, and Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) transect data, among several others. The site also offers general information on Red Tides, Red Tide conditions in Southwest Florida, a chronology of historic Red Tide events, and links to related resources.

305

Urban Ecology  

NSDL National Science Digital Library

When people think about the concept and idea of ecology, they may not immediately picture a bustling urban street or a network of interconnected bike paths. Since 1975, a group of architects and activists have been thinking about exactly those things in terms of urban ecology (and a good deal more to boot), coupling it with a conviction that urban ecology can draw on ecology, public participation and urban planning "to help design and build healthier cities." Given these ideas, it seems logical that this organization has its roots in the Bay Area, and continues to offer up interesting plans and proposals, many of which can be found on the website. One such document is the Walkable Streets Toolkit, which is designed for use by communities that seek to make their streets more pedestrian friendly. Additionally, visitors will want to look at current and past editions of The Urban Ecologist, which is the group's quarterly newsletter.

306

Procedural guidelines for ecological risk assessments at US Army Sites, Volume 2 - research and bimonitoring methods for the characterization of ecological effects. Final report, September 1992December 1994  

Microsoft Academic Search

The purpose of this report is to provide guidance for procedures to conduct ecological risk assessment (ERA) for use by risk assessors under contract to the U.S. Army Environmental Center (AEC) at Army National Priority (NPL) sites and sites listed under the Base Realignment and Closure (BRAC) program. This report contains information on more than 100 environmental models and test

M. Simini; T. W. LaPoint; J. D. Florian; T. K. Warren; K. R. Dixon

1995-01-01

307

Extracellular localization of galectin-3 has a deleterious role in joint tissues  

PubMed Central

In this study we examine the extracellular role of galectin-3 (gal-3) in joint tissues. Following intra-articular injection of gal-3 or vehicle in knee joints of mice, histological evaluation of articular cartilage and subchondral bone was performed. Further studies were then performed using human osteoarthritic (OA) chondrocytes and subchondral bone osteoblasts, in which the effect of gal-3 (0 to 10 ?g/ml) was analyzed. Osteoblasts were incubated in the presence of vitamin D3 (50 nM), which is an inducer of osteocalcin, encoded by an osteoblast terminal differentiation gene. Genes of interest mainly expressed in either chondrocytes or osteoblasts were analyzed with real-time RT-PCR and enzyme immunoassays. Signalling pathways regulating osteocalcin were analyzed in the presence of gal-3. Intra-articular injection of gal-3 induced knee swelling and lesions in both cartilage and subchondral bone. On human OA chondrocytes, gal-3 at 1 ?g/ml stimulated ADAMTS-5 expression in chondrocytes and, at higher concentrations (5 and 10 ?g/ml), matrix metalloproteinase-3 expression. Experiments performed with osteoblasts showed a weak but bipolar effect on alkaline phosphatase expression: stimulation at 1 ?g/ml or inhibition at 10 ?g/ml. In the absence of vitamin D3, type I collagen alpha 1 chain expression was inhibited by 10 ?g/ml of gal-3. The vitamin D3induced osteocalcin was strongly inhibited in a dose-dependent manner in the presence of gal-3, at both the mRNA and protein levels. This inhibition was mainly mediated by phosphatidylinositol-3-kinase. These findings indicate that high levels of extracellular gal-3, which could be encountered locally during the inflammatory process, have deleterious effects in both cartilage and subchondral bone tissues.

Janelle-Montcalm, Audree; Boileau, Christelle; Poirier, Francoise; Pelletier, Jean-Pierre; Guevremont, Melanie; Duval, Nicolas; Martel-Pelletier, Johanne; Reboul, Pascal

2007-01-01

308

Countergradient Selection for Rapid Growth in Pumpkinseed Sunfish: Disentangling Ecological and Evolutionary Effects  

Microsoft Academic Search

Abstract. Ecologists often assume,that the evolutionary,response,to an environmental gradient will be the same as the phenotypic response. However, under some circumstances the evolutionary response to a gradient may be opposite of the ecological response, a phenomenon,known,as ‘‘countergradient variation.’’ We had previously predicted that coun- tergradient selection has occurred,in pumpkinseed,sunfish in response,to a resource gradient created by competition,with bluegill sunfish. Because

Jeffrey David Arendt; David Sloan Wilson

1999-01-01

309

Effectiveness of university technology transfer: an organizational population ecology view of a maturing supplier industry  

Microsoft Academic Search

In this article, we propose that universities engaged in technology transfer activities can be viewed as the University Technology\\u000a Commercialization (UTC) industry. We use an organizational population ecology perspective to outline an economic model for\\u000a the analysis of the UTC industry. We introduce cohort analysis and time-lagged comparisons of multiple stages in the commercialization\\u000a process to examine the efficiency and

Richard Cardozo; Alexandre Ardichvili; Anthony Strauss

2011-01-01

310

Relative Effectiveness of Expository and Field Trip Methods of Teaching on Students' Achievement in Ecology  

ERIC Educational Resources Information Center

|The study was a pre-test treatment post-test control design. Three educational districts from the Niger Delta region of Nigeria were treated as clusters. Twenty boys and 20 girls were randomly selected, making up a total of 40 students, in each of Group A, Group B, and Group C. Students in Group A were taught ecology by taking them to the school…

Hamilton-Ekeke, Joy-Telu

2007-01-01

311

Population ecology of the polychaete Nephtys incisa in Long Island sound and the effects of disturbance  

Microsoft Academic Search

The infaunal polychaeteNephtys incisa is a dominant constituent of soft-bottom communities in nearshore New England waters. This study quantifies its population\\u000a ecology under natural conditions and following disturbance (dredge material disposal). Five stations in central Long Island\\u000a Sound (SREF, 1000E, 400E, 200E and CNTR) representing a gradient of increasing exposure to disposed materials were sampled\\u000a quarterly for 26 months between

Roman N. Zajac; Robert B. Whitlatch

1988-01-01

312

Ecological consequences of the bold–shy continuum: the effect of predator boldness on prey risk  

Microsoft Academic Search

Although the existence of different personality traits within and between animal populations has been relatively well established,\\u000a the ecological implications of this variation remain neglected. In this study we tested whether differences in the boldness\\u000a of pairs of three-spined sticklebacks led to differential predation risk in their prey, Chironomidae larvae. Bolder pairs,\\u000a those that left a refuge and crossed the

C. C. Ioannou; M. Payne; J. Krause

2008-01-01

313

Effects of habitat patchiness and connectivity on the spatial ecology of the root vole Microtus oeconomus  

Microsoft Academic Search

space[ Patchiness enhanced andconnectivity decreased the substructuring[Key!words] dispersal\\\\ aggregation\\\\ habitat fragmentation\\\\ _ssion and fusion response\\\\movement corridors\\\\ spatial statistics[Journal of Animal Ecology "0887# 56\\\\ 016039of habitat fragmentation by which human!inducedIntroductiondisturbances result in smaller\\\\ more isolated and{hard!edged| patches surrounded by a hostile matrix[ Habitat patchiness is believed to a}ect most aspectsof the biology of a population[ ...

Ottar N. Bjornstad; Harry P. Andreassen; Rolf A. Ims

1998-01-01

314

Using Ecological Theory to Evaluate the Effectiveness of an Indigenous Community Intervention: A Study of Sexual Assault Nurse Examiner (SANE) Programs  

Microsoft Academic Search

In recent years, there has been renewed interest among community psychologists in indigenous interventions, which are programs\\u000a created by local practitioners (rather than researchers) already rooted in their communities. Indigenous interventions have\\u000a strong ecological validity, but their effectiveness is often unknown because so few are rigorously evaluated. The goal of\\u000a this project was to use Kelly and Trickett’s ecological theory

Rebecca Campbell; Debra Patterson; Giannina Fehler-Cabral

2010-01-01

315

The effect of ecologically relevant variations in light level on the performance of Mongolian gerbils on two visual tasks.  

PubMed

Tests of rodent visual capacities are typically performed under standard laboratory illumination. However, light level can have subtle and complex effects on behavior in rodents. We tested Mongolian gerbils (Meriones unguiculatus) - a species that shows individual differences in activity pattern - on visual tasks at three ecologically relevant levels of ambient illuminance: approximating moonlight (1 lx), dawn or dusk (10 lx), and low daylight (100 lx). A jumping task and a grating discrimination quantified depth perception and grating acuity, respectively. Illuminance variations had important effects on behavior. Gerbils jumped faster in lower light on the depth discrimination task, but were also less accurate than in bright light. Daytime activity levels (possibly reflecting variations in activity pattern) mediated these effects, with animals that were awake during a lower proportion of daytime hours exhibiting a trend toward jumping faster with lower light level as compared to more day-active gerbils. Moreover, while illuminance did not affect acuity overall, it interacted with activity levels in a complex way: in both the darkest and lowest light levels, animals that were awake during a greater proportion of daytime hours showed higher acuity levels than animals that were less active during the day. These results indicate that gerbils show behavioral profiles in vision tasks that represent an interaction between visual ability and illuminance-sensitive motivational or emotional actors, perhaps including chronotype. Thus, the most ecologically relevant assessments of the visual performance of rodents will likely be achieved by testing at species-specific preferred light levels. PMID:21906663

Krysiak, Magdalena E; Bankieris, Kaitlyn R; Abid, Qura; Kui, Guan Hua; Rodman, Hillary R

2011-09-09

316

Ecological effects on streams from forest fertilization; literature review and conceptual framework for future study in the western Cascades  

USGS Publications Warehouse

Fertilization of forests with urea-nitrogen has been studied numerous times for its effects on water quality. Stream nitrogen concentrations following fertilization are typically elevated during winter, including peaks in the tens-of-thousands of parts per billion range, with summer concentrations often returning to background or near-background levels. Despite these increases, water-quality criteria for nitrogen have rarely been exceeded. However, such criteria are targeted at fish toxicity or human health and are not relevant to concentrations that could cause ecological disturbances.Studies of the responses of stream biota to fertilization have been rare and have targeted either immediate, toxicity-based responses or used methods insensitive to ongoing ecological processes. This report reviews water-quality studies following forest fertilizations, emphasizing Cascade streams in the Pacific Northwest and documented biological responses in those streams. A conceptual model predicting potential ecological response to fertilization, which includes effects on algal growth and primary production, is presented. In this model, applied fertilizer nitrogen reaching streams is mostly exported during winter. However, some nitrogen retained in soils or stream and riparian areas may become available to aquatic biota during spring and summer. Biological responses may be minimal in small streams nearest to application because of light limitation, but may be elevated downstream where light is sufficient to allow algal growth. Ultimately, algal response could be greatest in downstream reaches, although ambient nutrient concentrations remain low due to uptake and benthic nutrient recycling. Ground-water flow paths and hyporheic processing could be critical in determining the fate of applied nitrogen. A framework is provided for testing this response in the Little River watershed, a tributary to the North Umpqua River, Oregon, at basic and intensive levels of investigation.

Anderson, C. W.

2002-01-01

317

The effect of ecological parameters on the distribution of snail vectors of schistosomiasis.  

PubMed

The infestation of the water courses showed 32.5% for Biomphalaria alexandrina and 8.75% for Bulinus truncatus. Ecological parameters, showed non significant variations in the water courses harbouring snail vectors and those free from snails except for conductivity in the habitats harbouring B. truncatus. This variation was more highly significant (p<0.001). Of the examined sites, 11.25% were harbouring B. alexandrina and Lymnaea natalenesis living together and 5% of the sites were harbouring B. truncatus and Physa acuta snails. Snail vectors were distributed with different degrees with aquatic plants reflecting the degree of species preference plants for snails' life. PMID:12557938

Kader, A A

2001-04-01

318

Ringed-seal winter ecology and effects of noise disturbance. Final report  

SciTech Connect

The ecological importance of lair use and the responses of individual ringed seals to noise disturbance were studied telemetrically over three years. The objectives were: to determine the number of subnivean lairs utilized by individual ringed seals and the spatial distribution of those lairs; to determine the patterns of daily and seasonal use of subnivean lairs by ringed seals; to determine the thermal advantage realized by ringed seals occupying subnivean lairs; and to determine how lair occupancy is affected by noise disturbances, including seismic exploration.

Kelly, B.P.; Quakenbush, L.T.; Rose, J.R.

1986-12-01

319

Ecology of marine parasites  

Microsoft Academic Search

Important ecological aspects of marine parasites are discussed. Whereas effects of parasites on host individuals sometimes leading to death are known from many groups of parasites, effects on host populations have been studied much less. Mass mortalities have been observed mainly among hosts occurring in abnormally dense populations or after introduction of parasites by man. As a result of large-scale

K. Rohde

1984-01-01

320

Ecological niche  

SciTech Connect

The ecological niche of an organism is the set of environmental conditions under which the particular functions of the organism could be expected to assure its survival. It comprises both the set of conditions where the organism lives (often termed the habitat of the organism) and the functional role of the organism in the ecosystem. Recent works in niche theory have enabled ecologists to develop predictions and actual applications. The history of the niche concept, applications of niche theory, and ecological differences between similar species are discussed.

Shugart, H.H.

1980-01-01

321

Defending Ecology.  

ERIC Educational Resources Information Center

|Explains how non-native species' problems in the ecosystem can introduce fundamental ecological principles in the classroom. Provides background information on damages caused by non-native species. Discusses how educators can use this environmental issue in the classroom and gives the example of zebra mussels. Lists instructional strategies for…

Margolis, Brian

2000-01-01

322

Restoration Ecology  

NSDL National Science Digital Library

While not a panacea, the emerging field of restoration ecology provides an important tool for environmental conservation and contributes greatly to our understanding of ecology.The first Web site is the home page of the Society for Ecological Restoration, offering a good starting point for exploring this relatively new discipline (1). The next site (2) provides an overview of the University of Wisconsin's Center for Restoration Ecology, "the first comprehensive, interdisciplinary research team assembled to advance the science and technology of ecosystem restoration." The National Oceanic and Atmospheric Administration outlines its plans for coastal and estuarine restoration in this Web site (3). The Fermi National Accelerator Laboratory in Illinois has implemented one of the largest tallgrass prairie restorations to date (4). The Kissimmee River Restoration Web site (5) provides a detailed look at this incredibly ambitious dam removal and wetland restoration project in Florida. The next Web site (6) offers a visually-attractive introduction to the restoration efforts of the nonprofit organization RESTORE, focusing on the forests of Maine. The Wildlands Project, another restoration-oriented nonprofit organization, describes its vision of ecosystem conservation in this Web site, which includes a personal brief from distinguished biologist E. O. Wilson. (7). The Wildwood project of the Scottish organization Carrifran offers an interesting contrast to restoration efforts in the US, as much of Scotland has been denuded of its original forests for thousands of years (8).

Sohmer, Rachel.

2002-01-01

323

Trash Ecology  

ERIC Educational Resources Information Center

|A hands on activity involving density, frequency and biomass using transects, quadrats and a local good deed by cleaning up the neighborhood while practicing important techniques in ecology is detailed. The activity is designed for KCC-STEP, whose primary goal is to expand the scientific knowledge and research experiences of their students, who…

Lind, Georgia J.

2004-01-01

324

Defending Ecology.  

ERIC Educational Resources Information Center

Explains how non-native species' problems in the ecosystem can introduce fundamental ecological principles in the classroom. Provides background information on damages caused by non-native species. Discusses how educators can use this environmental issue in the classroom and gives the example of zebra mussels. Lists instructional strategies for…

Margolis, Brian

2000-01-01

325

Nitrogen deposition effects on Mediterranean-type ecosystems: an ecological assessment.  

PubMed

We review the ecological consequences of N deposition on the five Mediterranean regions of the world. Seasonality of precipitation and fires regulate the N cycle in these water-limited ecosystems, where dry N deposition dominates. Nitrogen accumulation in soils and on plant surfaces results in peaks of availability with the first winter rains. Decoupling between N flushes and plant demand promotes losses via leaching and gas emissions. Differences in P availability may control the response to N inputs and susceptibility to exotic plant invasion. Invasive grasses accumulate as fuel during the dry season, altering fire regimes. California and the Mediterranean Basin are the most threatened by N deposition; however, there is limited evidence for N deposition impacts outside of California. Consequently, more research is needed to determine critical loads for each region and vegetation type based on the most sensitive elements, such as changes in lichen species composition and N cycling. PMID:21277663

Ochoa-Hueso, Raúl; Allen, Edith B; Branquinho, Cristina; Cruz, Cristina; Dias, Teresa; Fenn, Mark E; Manrique, Esteban; Pérez-Corona, M Esther; Sheppard, Lucy J; Stock, William D

2011-02-01

326

Family Wellness: An Ecological Perspective.  

ERIC Educational Resources Information Center

Bronfenbrenner's (1979) concept of human ecology emphasizes the effect of the environment, both physical and psychological, on individual development. Bronfenbrenner's contexts which affect the development of the individual (microsystem, mesosystem, exosystem, macrosystem) can also be defined for the family in an ecological model of family…

Fannin, Ronald A.

327

Acidity, nutrients and minerals in atmospheric precipitation over Florida: Deposition patterns, mechanisms and ecological effects. Final Report, Sep. 1977 - Dec. 1979  

SciTech Connect

Deposition patterns, mechanisms and ecological effects from atmospheric precipitation were examined. The results are summarized according to the three major phases of the project: (1) atmospheric deposition of nutrients and minerals (2) the spatial and temporal distribution of rainfall acidity in Florida and (3) the effects of acidification on chemical and biological conditions in softwater lakes of Florida.

Brezonik, P.L.; Hendry, C.D., Jr.; Edgerton, E.S.; Schulze, R.L.; Crisman, T.L.

1983-02-01

328

Exome Sequencing of Only Seven Qataris Identifies Potentially Deleterious Variants in the Qatari Population  

PubMed Central

The Qatari population, located at the Arabian migration crossroads of African and Eurasia, is comprised of Bedouin, Persian and African genetic subgroups. By deep exome sequencing of only 7 Qataris, including individuals in each subgroup, we identified 2,750 nonsynonymous SNPs predicted to be deleterious, many of which are linked to human health, or are in genes linked to human health. Many of these SNPs were at significantly elevated deleterious allele frequency in Qataris compared to other populations worldwide. Despite the small sample size, SNP allele frequency was highly correlated with a larger Qatari sample. Together, the data demonstrate that exome sequencing of only a small number of individuals can reveal genetic variations with potential health consequences in understudied populations.

Rodriguez-Flores, Juan L.; Fuller, Jennifer; Hackett, Neil R.; Salit, Jacqueline; Malek, Joel A.; Al-Dous, Eman; Chouchane, Lotfi; Zirie, Mahmoud; Jayoussi, Amin; Mahmoud, Mai A.; Crystal, Ronald G.; Mezey, Jason G.

2012-01-01

329

corRna: a web server for predicting multiple-point deleterious mutations in structural RNAs  

PubMed Central

RNA molecules can achieve a broad range of regulatory functions through specific structures that are in turn determined by their sequence. The prediction of mutations changing the structural properties of RNA sequences (a.k.a. deleterious mutations) is therefore useful for conducting mutagenesis experiments and synthetic biology applications. While brute force approaches can be used to analyze single-point mutations, this strategy does not scale well to multiple mutations. In this article, we present corRna a web server for predicting the multiple-point deleterious mutations in structural RNAs. corRna uses our RNAmutants framework to efficiently explore the RNA mutational landscape. It also enables users to apply search heuristics to improve the quality of the predictions. We show that corRna predictions correlate with mutagenesis experiments on the hepatitis C virus cis-acting replication element as well as match the accuracy of previous approaches on a large test-set in a much lower execution time. We illustrate these new perspectives offered by corRna by predicting five-point deleterious mutations—an insight that could not be achieved by previous methods. corRna is available at: http://corrna.cs.mcgill.ca.

Lam, Edmund; Kam, Alfred; Waldispuhl, Jerome

2011-01-01

330

Somatic deleterious mutation rate in a woody plant: estimation from phenotypic data.  

PubMed

We conducted controlled crosses in populations of the long-lived clonal shrub, Vaccinium angustifolium (lowbush blueberry) to estimate inbreeding depression and mutation parameters associated with somatic deleterious mutation. Inbreeding depression level was high, with many plants failing to set fruit after self-pollination. We also compared fruit set from autogamous pollinations (pollen collected from within the same inflorescence) with fruit set from geitonogamous pollinations (pollen collected from the same plant but from inflorescences separated by several meters of branch growth). The difference between geitonogamous versus autogamous fitness within single plants is referred to as 'autogamy depression' (AD). AD can be caused by somatic deleterious mutation. AD was significantly different from zero for fruit set. We developed a maximum-likelihood procedure to estimate somatic mutation parameters from AD, and applied it to geitonogamous and autogamous fruit set data from this experiment. We infer that, on average, approximately three sublethal, partially dominant somatic mutations exist within the crowns of the plants studied. We conclude that somatic mutation in this woody plant results in an overall genomic deleterious mutation rate that exceeds the rate measured to date for annual plants. Some implications of this result for evolutionary biology and agriculture are discussed. PMID:23778990

Bobiwash, K; Schultz, S T; Schoen, D J

2013-06-19

331

Ecology and Society  

NSDL National Science Digital Library

Formerly Conservation Ecology, this electronic, open access, peer-reviewed, multi-disciplinary journal provides research findings on the management, stewardship and sustainable use of ecological systems, resources and biological diversity at all levels, the role natural systems play in social and political systems, and the effect of social, economic and political institutions on ecological systems. All articles from all back issues are available in the archives from the first issue published in 1994 to the most current issue in progress; visitors can find these by clicking on the "Find back issues" link to the right. As always, submission guidelines and journal policies are also available for those looking to publish in the journal.

Folke, Carl; Gunderson, Lance H.

2007-04-28

332

Ecological Aesthetics  

Microsoft Academic Search

\\u000a The emerging subdiscipline of ecological aesthetics concerns the aesthetic appreciation of the world in its entirety, including\\u000a both the natural and built environments, and is consequently the broadest category of aesthetics. This area of study emerged\\u000a as a distinct field in the latter half of the twentieth century, although its historical roots may be traced to eighteenth\\u000a century British and

Ted Toadvine

333

Animal Ecology  

NSDL National Science Digital Library

This tutorial introduces students to the concept of animal ecology. The first section explains the different ways animals use camouflage. There is also a discussion of how the process of decay breaks organic matter down into nutrients, and how simple aquatic organisms (algae, zooplankton) provide a food source for larger organisms. The concept of food chains is introduced, and land-based and aquatic examples are described. A quiz and glossary are included.

334

An Application of a Mixed-Effects Location Scale Model for Analysis of Ecological Momentary Assessment (EMA) Data  

PubMed Central

Summary For longitudinal data, mixed models include random subject effects to indicate how subjects influence their responses over repeated assessments. The error variance and the variance of the random effects are usually considered to be homogeneous. These variance terms characterize the within-subjects (i.e., error variance) and between-subjects (i.e., random-effects variance) variation in the data. In studies using ecological momentary assessment (EMA), up to 30 or 40 observations are often obtained for each subject, and interest frequently centers around changes in the variances, both within and between subjects. In this article, we focus on an adolescent smoking study using EMA where interest is on characterizing changes in mood variation. We describe how covariates can influence the mood variances, and also extend the standard mixed model by adding a subject-level random effect to the within-subject variance specification. This permits subjects to have influence on the mean, or location, and variability, or (square of the) scale, of their mood responses. Additionally, we allow the location and scale random effects to be correlated. These mixed-effects location scale models have useful applications in many research areas where interest centers on the joint modeling of the mean and variance structure.

Hedeker, Donald; Mermelstein, Robin J.; Demirtas, Hakan

2008-01-01

335

Ecological Theory and Community Restoration Ecology  

Microsoft Academic Search

Community ecological theory may play an important role in the development of a science of restoration ecology. Not only will the practice of restoration bene- fit from an increased focus on theory, but basic re- search in community ecology will also benefit. We pose several major thematic questions that are rele- vant to restoration from the perspective of community ecological

Margaret A. Palmer; Richard F. Ambrose; N. LeRoy Poff

1997-01-01

336

Aspen Ecology in Rocky Mountain National Park: Age Distribution, Genetics, and the Effects of Elk Herbivory  

SciTech Connect

Lack of aspen (Populus tremuloides) recruitment and canopy replacement of aspen stands that grow on the edges of grasslands on the low-elevation elk (Cervus elaphus) winter range of Rocky Mountain National Park (RMNP) in Colorado has been a cause of concern for more than 70 years (Packard, 1942; Olmsted, 1979; Stevens, 1980; Hess, 1993; R.J. Monello, T.L. Johnson, and R.G. Wright, Rocky Mountain National Park, 2006, written commun.). These aspen stands are a significant resource since they are located close to the park's road system and thus are highly visible to park visitors. Aspen communities are integral to the ecological structure of montane and subalpine landscapes because they contain high native species richness of plants, birds, and butterflies (Chong and others, 2001; Simonson and others, 2001; Chong and Stohlgren, 2007). These low-elevation, winter range stands also represent a unique component of the park's plant community diversity since most (more than 95 percent) of the park's aspen stands grow in coniferous forest, often on sheltered slopes and at higher elevations, while these winter range stands are situated on the low-elevation ecotone between the winter range grasslands and some of the park's drier coniferous forests.

Tuskan, Gerald A [ORNL; Yin, Tongming [ORNL

2008-10-01

337

The Landscape Ecology of Invasive Spread  

Microsoft Academic Search

Although habitat loss, fragmentation, and invasive species collectively pose the greatest threats to biodiversity, little theoretical or empirical research has addressed the effects of landscape structure—or spa- tial pattern more generally—on the spread of invasive species. Landscape ecology is the study of how spatial pattern affects ecological process. Thus, a landscape ecology of invasive spread involves understanding how spatial pattern,

2002-01-01

338

Distributed processing applied to ecological modeling  

Microsoft Academic Search

Ecological simulation models are widely used in ecology to help understand and predict the behavior of ecosystems. Many of the questions now being asked in ecology, such as the effects of climate change on ecosystems or the risks to ecosystems from contaminants, require extrapolation in both space and time and often require the collaboration of scientists from several fields of

Thomas B. Kirchner

1997-01-01

339

Aquatic predicted no-effect concentration for three polycyclic aromatic hydrocarbons and probabilistic ecological risk assessment in Liaodong Bay of the Bohai Sea, China.  

PubMed

Predicted no-effect concentration (PNEC) is often used in ecological risk assessment to determine low-risk concentrations for chemicals. In the present study, native marine species were selected for toxicity testing. The PNECs for three polycyclic aromatic hydrocarbons (PAHs), specifically phenanthrene (Phe), pyrene (Pyr), and benzo[a]pyrene (BaP), were derived from chronic and acute toxicity data with log-normal statistical methods. The achieved PNECs for Phe, Pyr, and BaP were 2.33, 1.09, and 0.011 ?g/L, respectively. In Jinzhou Bay and the Shuangtaizi River Estuary of Liaodong Bay in the Bohai Sea, China, the surface water concentrations of the three PAHs were analyzed by gas chromatography-mass spectrometry. Based on two probabilistic ecological risk assessment (PERA) methods, namely probabilistic risk quotient and joint probability curve, the potential risk of Phe, Pyr, and BaP in Jinzhou Bay and Shuangtaizi River Estuary was assessed. The same order of ecological risk (BaP > Phe > Pyr) was found by both models. Our study considered regional characteristics of marine biota during the calculation of PNECs, and the PERA methods provided probabilities of potential ecological risks of chemicals. Within the study area, further research on BaP is required due to its high potential ecological risk. PMID:23608972

Wang, Ying; Wang, Juying; Mu, Jingli; Wang, Zhen; Yao, Ziwei; Lin, Zhongsheng

2013-04-23

340

Ecological Momentary Assessment of Affect, Stress, and Binge-Purge Behaviors: Day of Week and Time of Day Effects in the Natural Environment  

PubMed Central

Objective The present study examined ecological momentary assessments of binge/vomit behavior, mood, and type and severity of stressors in a sample of 133 women with bulimia nervosa. Method Participants completed an ecological momentary assessment protocol for a period of 2 weeks. Results Mixed-effects and multilevel logistic models revealed significant variation across time of day and day of the week in the occurrence of binging, vomiting, positive and negative affect, and the severity and types of stressful events. Discussion These findings explicate how momentary and daily experiences vary in the natural environments of women with bulimia nervosa, and document critical time periods for intervention.

Smyth, Joshua M.; Wonderlich, Stephen A.; Sliwinski, Martin J.; Crosby, Ross D.; Engel, Scott G.; Mitchell, James E.; Calogero, Rachel M.

2010-01-01

341

Evaluation of the effect of ecologic on root knot nematode, Meloidogyne incognita, and tomato plant, Lycopersicon esculenum.  

PubMed

Nonchemical methods and strategies for nematode management including cultural methods and engineered measures have been recommended as an alternative to methyl bromide (a major soil fumigant), due to its role in the depletion of the ozone layer. Hence, an international agreement has recently been reached calling for its reduced consumption and complete phasing out. This present research evaluates the potential of Ecologic, a biological, marine shell meal chitin material, as a soil amendment management agent for root knot nematode, Meloidogyne incognita, control, and its effect on the growth of Floradel tomato plant, Lycopersicon esculentum. To accomplish this goal, studies were conducted during which, experimental pots were set up in greenhouse environments using sterilized soil inoculated with 5,000 root-knot eggs per 1500 g soil. There were 4 treatments and 5 replications. Treatments were: No chitin; 50 g chitin; 100 g chitin; and 200 g chitin. A two-week wait period following Ecologic amendment preceded Floradel tomato planting to allow breakdown of the chitin material into the soil. Fresh and dry weights of shoot and root materials were taken as growth end-points. A statistically significant difference (p < or = 0.05) was obtained with regard to the growth rate of L. esculentum at 100 g chitin treatment compared to the control with no chitin. Mean fresh weights of Floradel tomato were 78.0 +/- 22.3 g, 81.0 +/- 20.3 g, 109.0 +/- 25.4 g and 102.0 +/- 33.3 g at 0, 50, 100 and 200 g chitin, respectively. The analysis of root knot nematode concentrations indicated a substantial effect on reproduction rate associated with chitin amendment. Study results showed a significant decrease in both root knot nematode eggs and juveniles (J2) at 100g and 200 g Ecologic chitin levels, however, an increase in nematode concentrations was recorded at the 50 g Ecologic chitin level (p < or = 0.05). The mean amounts of J2 population, as expressed per 1500 cm3 soil, were 49,933 +/- 38,819, 86,050 +/- 25248, 103 +/- 133 and 103 +/- 133 for 0, 50, 100 and 200 g chitin, respectively. Similarly, the mean numbers of root knot nematode eggs (per 1500 cm3 of soil) were 40,759 +/- 36,712, 66,048 +/- 39,730, 9,904 +/- 16,591 and 9,257 +/- 17,204. Root gall rating was also significantly lower (p < or = 0.05) at the 100 g and 200 g chitin levels compared to the control. Percent gall ratings were 3.3 +/- 1.0%, 3.2 +/- 1.0%, 1.0 +/- 0.5%, and 1.0% +/- 0.6% for amendment levels of 0, 50, 100, and 200 g chitin, respectively. PMID:18678924

Ladner, Debora C; Tchounwou, Paul B; Lawrence, Gary W

2008-06-01

342

Disruption of a Plant-Lizard Seed Dispersal System and Its Ecological Effects on a Threatened Endemic Plant in the Balearic Islands  

Microsoft Academic Search

The introduction of exotic species to an island can have significant effects on the population density and distribution of native species and on the ecological and evolutionary interactions among them (e.g., plant-animal mutualisms). The disruption of these interactions can be dramatic, significantly reducing the reproductive success of the species and even leading to their extinction. On Menorca Island (Balearic Islands,

ANNA TRAVESET; NURIA RIERA

2005-01-01

343

An Ecological Momentary Assessment of the Effects of Weight and Shape Social Comparisons on Women With Eating Pathology, High Body Dissatisfaction, and Low Body Dissatisfaction  

Microsoft Academic Search

This research examined the effects of naturally occurring appearance comparisons on women's affect, body satisfaction, and compensatory cognitions and behaviors. Using ecological momentary assessment, women with high body dissatisfaction and eating pathology (EPHB), high body dissatisfaction (HB), or low body dissatisfaction (LB) recorded their reactions to appearance-focused social comparisons. EPHB and HB women made more upward appearance comparisons than LB

Janis H. Crowther; Jeffrey A. Ciesla

2011-01-01

344

Identifying reefs of hope and hopeful actions: contextualizing environmental, ecological, and social parameters to respond effectively to climate change.  

PubMed

Priorities for conservation, management, and associated activities will differ based on the interplay between nearness of ecosystems to full recovery from a disturbance (pristineness), susceptibility to climate change (environmental susceptibility [ES]), and capacity of human communities to cope with and adapt to change (social adaptive capacity [AC]). We studied 24 human communities and adjacent coral reef ecosystems in 5 countries of the southwestern Indian Ocean. We used ecological measures of abundance and diversity of fishes and corals, estimated reef pristineness, and conducted socioeconomic household surveys to determine the AC of communities adjacent to selected coral reefs. We also used Web-based oceanographic and coral mortality data to predict each site's ES to climate warming. Coral reefs of Mauritius and eastern Madagascar had low ES and consequently were not predicted to be affected strongly by warm water, although these sites were differentiated by the AC of the human community. The higher AC in Mauritius may increase the chances for successful self-initiated recovery and protective management of reefs of this island. In contrast, Madagascar may require donor support to build AC as a prerequisite to preservation efforts. The Seychelles and Kenya had high ES, but their levels of AC and disturbance differed. The high AC in the Seychelles could be used to develop alternatives to dependence on coral reef resources and reduce the effects of climate change. Pristineness weighted toward measures of fish recovery was greatest for Kenya's marine protected areas; however, most protected areas in the region were far from pristine. Conservation priorities and actions with realistic chances for success require knowledge of where socioecological systems lie among the 3 axes of environment, ecology, and society. PMID:19245493

McClanahan, T R; Cinner, J E; Graham, N A J; Daw, T M; Maina, J; Stead, S M; Wamukota, A; Brown, K; Venus, V; Polunin, N V C

2009-02-24

345

Compliance to a Cell Phone-Based Ecological Momentary Assessment Study: The Effect of Time and Personality Characteristics  

ERIC Educational Resources Information Center

|Ecological momentary assessment (EMA) is a method that is now widely used to study behavior and mood in the settings in which they naturally occur. It maximizes ecological validity and avoids the limitations of retrospective self-reports. Compliance patterns across time have not been studied. Consistent compliance patterns could lead to data not…

Courvoisier, Delphine S.; Eid, Michael; Lischetzke, Tanja

2012-01-01

346

Ecological effects of crude oil residues on the functional diversity of soil microorganisms in three weed rhizospheres.  

PubMed

Ecological effects of crude oil residues on weed rhizospheres are still vague. The quantitative and diversity changes and metabolic responses of soil-bacterial communities in common dandelion (Taraxacum officinale), jerusalem artichoke (Silphium perfoliatum L.) and evening primrose (Acalypha australis L.) rhizospheric soils were thus examined using the method of carbon source utilization. The results indicated that there were various toxic effects of crude oil residues on the growth and reproduction of soil bacteria, but the weed rhizospheres could mitigate the toxic effects. Total heterotrophic counting colony-forming units (CFUs) in the rhizospheric soils were significantly higher than those in the non-rhizospheric soils. The culturable soil-bacterial CFUs in the jerusalem artichoke (S. perfoliatum) rhizosphere polluted with 0.50 kg/pot of crude oil residues were almost twice as much as those with 0.25 kg/pot and without the addition of crude oil residues. The addition of crude oil residues increased the difference in substrate evenness, substrate richness, and substrate diversity between non-rhizospheric and rhizospheric soils of T. officinale and A. australis, but there was no significant (p>0.05) difference in the Shannon's diversity index between non-rhizospheric and rhizospheric soils of S. perfoliatum. The rhizospheric response of weed species to crude oil residues suggested that S. perfoliatum may be a potential weed species for the effective plant-microorganism bioremediation of contaminated soils by crude oil residues. PMID:17294949

Zhang, Qian-ru; Zhou, Qi-xing; Ren, Li-ping; Zhu, Yong-guan; Sun, Shu-lan

2006-01-01

347

Signale aus der Natur. 10 Jahre oekologisches Wirkungskataster Baden-Wuerttemberg. (Signals from nature. The ten-year history of the register of ecological effects of Baden-Wuerttemberg).  

National Technical Information Service (NTIS)

The register of ecological effects aims to weight pollutant effects in nature. In order to establish such effects, plants and animals are investigated that constitute biological indicators reacting to pollutants with visible damage or by accumulation of t...

1994-01-01

348

Industrial ecology.  

PubMed Central

Industrial ecology addresses issues that will impact future production, use, and disposal technologies; proper use of the concept should reduce significantly the resources devoted to potential remediation in the future. This cradle-to-reincarnation production philosophy includes industrial processes that are environmentally sound and products that are environmentally safe during use and economically recyclable after use without adverse impact on the environment or on the net cost to society. This will require an industry-university-government round table to set the strategy and agenda for progress.

Patel, C K

1992-01-01

349

Ecology Explorers  

NSDL National Science Digital Library

This Web site from the Center for Environmental Studies at Arizona State University was developed as part of the Central Arizona-Phoenix Long-term Ecological Research Project (CAP LTER), but can be used by any classrooms interested in exploring urban ecosystems that surround them. Students and teachers learn about the scientific method and several data collection protocols that they can use right in their schoolyard. The site is attractive and easy to navigate; information is explained clearly and logically. A number of lesson plans for a variety of K-12 age groups will help teachers incorporate activities from this Web site into their classroom.

350

Watershed Ecology  

NSDL National Science Digital Library

Another informative Web site from the Environmental Protection Agency is the Online Training in Watershed Management page. Here, citizens have access to a wealth of information and tools to help them understand and protect their water resources. Six "modules" are offered, each of which take between a half to two hours to complete. They are organized by theme including an Introduction, watershed ecology, watershed change, analysis and planning, management practices, and community/ social/ water law. Each includes easy-to-follow and thorough descriptions, along with any additional resources that may be needed.

2000-01-01

351

Industrial ecology.  

PubMed

Industrial ecology addresses issues that will impact future production, use, and disposal technologies; proper use of the concept should reduce significantly the resources devoted to potential remediation in the future. This cradle-to-reincarnation production philosophy includes industrial processes that are environmentally sound and products that are environmentally safe during use and economically recyclable after use without adverse impact on the environment or on the net cost to society. This will require an industry-university-government round table to set the strategy and agenda for progress. PMID:11607254

Patel, C K

1992-02-01

352

The cumulative effects of resource development on biodiversity and ecological integrity in the Peace-Moberly region of Northeast British Columbia, Canada  

Microsoft Academic Search

Rapid acceleration of industrial development in north-eastern British Columbia is currently occurring without a comprehensive\\u000a assessment of the effects it will have on ecological or cultural systems. The cumulative effects of past development are already\\u000a being felt within the Treaty 8 First Nations of the region but these effects have not been quantified from a landscape point\\u000a of view. Using

Craig R. Nitschke

2008-01-01

353

Effect of dam parity on litter performance, transfer of passive immunity, and progeny microbial ecology.  

PubMed

Litter performance and progeny health status may be decreased in progeny derived from primiparous sows but improve with increasing parity. The objective was to evaluate litter performance, the production and passive transfer of Ig, and fecal microbial populations in progeny derived from first parity (P1) compared with fourth parity (P4) dams. Litter performance was recorded for P1 (n = 19) and P4 (n = 24) dams including number of pigs/litter (total born, born live, stillbirths, mummified fetuses, prewean mortality, and pigs weaned) and average litter and piglet BW at birth (d 0), d 7, d 14, and at weaning (average d 19). Blood samples were collected from all dams on d 90 and 114 of gestation and d 0 of lactation. Colostrum and milk samples were collected from each dam on d 0, 7, and 14 of lactation for quantification of IgG and IgA. Blood and fecal samples were collected from each litter (n = 6 pigs/litter) on d 1, 7, and 14 after parturition. Circulating IgG and IgA concentrations were quantified in all blood samples. Denaturing gradient gel electrophoresis (DGGE) was used to characterize similarity and diversity of fecal microbes among progeny. Progeny of P1 dams had decreased average litter BW at d 7 (25.7 vs. 30.0 kg; P < 0.03) and decreased average piglet BW throughout the experiment (d 0, 7, 14, and 19; P < 0.001) compared with P4 progeny. No parity × day interactions were observed with respect to immunoglobulin or microbial analyses. Concentrations of IgA tended to be greater (P = 0.09) in samples of colostrum and milk obtained from P4 compared with P1 dams. Serum IgG concentrations were greater (P < 0.02) in P4 progeny compared with P1 progeny. Results of DGGE revealed that P1 progeny had increased (P < 0.001) microbial similarity on d 7 and decreased (P < 0.03) microbial similarity on d 14 compared with P4 progeny. Progeny of P1 dams tended (P = 0.07) to have a greater Shannon's diversity index compared with P4 progeny on d 1, and P1 progeny had a greater (P < 0.03) Shannon's diversity index compared with P4 progeny on d 7. Litter performance, passive transfer of immunity, and progeny microbial ecology were affected by dam parity. PMID:23482585

Carney-Hinkle, E E; Tran, H; Bundy, J W; Moreno, R; Miller, P S; Burkey, T E

2013-03-12

354

Stimulatory effects of tannins and cholic acid on tryptic hydrolysis of proteins: Ecological implications  

Microsoft Academic Search

The biochemical basis for considering tannins as digestion inhibitors has been reexamined. Both stimulatory and inhibitory effects of tannins on tryptic hydrolysis are reported. We show how stimulation may result from tannin-induced structural changes in the substrate protein, effectively denaturing it. The surfactant and bile constituent cholic acid also produced similar stimulatory effects. These results have considerable implications for normal

Simon Mole; Peter G. Waterman

1985-01-01

355

Population ecology of wild sunflowers: effects of seed density and post-dispersal vertebrate seed predators  

Microsoft Academic Search

Assessing the effects of seed density on the population dynamics of wild plant species with crop relatives will be vital in determining the potential effects of introducing traits into wild populations as a result of crop-to-wild gene flow. We examined experimental sunflower (Helianthus annuus) patches in eastern Kansas to determine the effects of seed density and predation on seedling recruitment

Charity L. Cummings; Helen M. Alexander

2002-01-01

356

One step beyond lethal equivalents: characterization of deleterious loci in the rapid cycling Brassica rapa L. base population  

Microsoft Academic Search

The total number of lethal equivalents as defined by Morton, Crow and Muller (1956) is a function of three parameters: M,\\u000a the number of loci at which deleterious mutations can occur, q, the frequency of the deleterious alleles at each locus, and\\u000a s, their selective value. A new approach based on multi?generation inbreeding data is outlined and used to infer

Martin Lascoux; Jae Kyun Lee

1998-01-01

357

Review article. Studying climate effects on ecology through the use of climate indices: the North Atlantic Oscillation, El Niño Southern Oscillation and beyond.  

PubMed

Whereas the El Niño Southern Oscillation (ENSO) affects weather and climate variability worldwide, the North Atlantic Oscillation (NAO) represents the dominant climate pattern in the North Atlantic region. Both climate systems have been demonstrated to considerably influence ecological processes. Several other large-scale climate patterns also exist. Although less well known outside the field of climatology, these patterns are also likely to be of ecological interest. We provide an overview of these climate patterns within the context of the ecological effects of climate variability. The application of climate indices by definition reduces complex space and time variability into simple measures, 'packages of weather'. The disadvantages of using global climate indices are all related to the fact that another level of problems are added to the ecology-climate interface, namely the link between global climate indices and local climate. We identify issues related to: (i) spatial variation; (ii) seasonality; (iii) non-stationarity; (iv) nonlinearity; and (v) lack of correlation in the relationship between global and local climate. The main advantages of using global climate indices are: (i) biological effects may be related more strongly to global indices than to any single local climate variable; (ii) it helps to avoid problems of model selection; (iii) it opens the possibility for ecologists to make predictions; and (iv) they are typically readily available on Internet. PMID:14561270

Stenseth, Nils Chr; Ottersen, Geir; Hurrell, James W; Mysterud, Atle; Lima, Mauricio; Chan, Kung-Sik; Yoccoz, Nigel G; Adlandsvik, Bjørn

2003-10-22

358

Principles of Political Ecology.  

National Technical Information Service (NTIS)

Presented are the concepts and principles of political ecology, i.e., the application of ecological principles to public affairs. The public issues of direct concern in political ecology are environmental quality; energy, materials, and other natural reso...

R. L. Shelton

1976-01-01

359

Effects-based marine ecological risk assessment at a polychlorinated biphenyl-contaminated site in Saglek, Labrador, Canada.  

PubMed

Although the presence and distribution of polychlorinated biphenyls (PCBs) in Arctic marine environments has been well documented, the implications for the health of biota are poorly understood. In the present study, multiple lines of evidence, including site-specific effects data, were used to assess PCB-related risks to marine biota at a contaminated military site in Saglek Bay, Labrador, Canada, from 1997 to 1999. Risks were evaluated for three components of the ecosystem: benthic invertebrates, a bottom-feeding fish (shorthorn sculpin, Myoxocephalus scorpius), and a diving seabird (black guillemot, Cepphus grylle). Average sediment PCB concentrations exceeded the Canadian interim sediment quality guideline level by 41-fold. However, sediment toxicity testing and a benthic community survey showed no evidence of adverse effects. In contrast, shorthorn sculpin and black guillemot PCB exposures (measured as sum of 55 congeners) were elevated enough to pose risks to survival or reproduction. Based on the collective evidence, the authors estimated that risks were posed by sediment PCB concentrations greater than 77?ng/g dry weight for black guillemots and 750?ng/g dry weight for shorthorn sculpins. The present study, along with two parallel studies, provided information to support the management decisions concerning potential remedial action on the contaminated sediments. This ecological risk assessment describes the steps and rationale taken to evaluate the risk posed by an area of PCB-contaminated marine sediments in an otherwise relatively pristine northern coastal environment. PMID:23147987

Brown, Tanya M; Kuzyk, Zou Zou A; Stow, Jason P; Burgess, Neil M; Solomon, Steve M; Sheldon, Tom A; Reimer, Ken J

2012-12-28

360

Antioxidant and prooxidant effects of lanthanum ions on Vicia faba L. seedlings under cadmium stress, suggesting ecological risk.  

PubMed

The present study combined chemical analyses and biological measurements to investigate biphasic effects of La on Cd stress in leaves of Vicia faba seedlings, which were hydroponically cultivated for 15 d in the combination of 6 µM CdCl(2) and 2 to 480 µM La(NO(3))(3), respectively. The results showed that contents of Cd first elevated above and then declined below the 6 µM single Cd treatment when 2 to 30 µM extraneous La were combined. Contents of mineral nutrients altered differentially and became imbalanced. No distinct band was observed in catalase (CAT), guaiacol peroxidase (GPX), or ascorbate peroxidase (APX) patterns, but in superoxide dismutase (SOD) isozymes by the supplementation with 8 to 480 µM of extraneous La. Superoxide dismutase and APX activities changed as a U-shaped curve; however, CAT and GPX changed as an inverted U-shaped curve along with increasing La. Moreover, heat shock protein 70 (HSP 70) production was reduced below the single treatment of Cd at 2 to 8 µM of extraneous La and enhanced thereafter. Thus, La at lower concentrations promoted antioxidation against Cd stress; La at higher concentrations turned to prooxidant effects, implicating potential ecological risk. Heat shock protein 70, combined with the antioxidant enzymes, constitutes an integrative defense system, which can be used to estimate the degree of antioxidation or prooxidation of extraneous La to Cd-induced oxidative stress in the seedlings. PMID:22447248

Wang, Cheng-Run; Xiao, Jia-Jun; Tian, Yuan; Bao, Xia; Liu, Ling; Yu, Yan; Wang, Xiao-Rong; Chen, Tian-Yu

2012-04-18

361

A deleterious founder mutation in the BMPER gene causes diaphanospondylodysostosis (DSD).  

PubMed

Diaphonospondylodysostosis (DSD) is a rare, recessively inherited, lethal skeletal dysplasia, characterized by severe spinal ossification, segmentation defects, and renal cystic dysplasia with nephrogenic rests. We hereby present three affected individuals: two children and a fetus from two unrelated East Jerusalem Arab-Muslim families. Whereas most fetuses die in utero or perinatally, one of the children survived to 15 months. Homozygosity mapping in the two families demonstrated a single common 3.87 Mb region on chromosome 7, ruling out previously known spondylocostal/spondylothoracic dysostosis loci. The 15 protein coding genes in the region were prioritized, and some were sequenced. A single, novel deleterious mutation, Q104X, was detected in the bone morphogenetic protein-binding endothelial regulator protein (BMPER) gene, recently reported to be mutated in other DSD patients [Funari et al., 2010]. The novel mutation we identified is an ancestral founder allele, as evidenced by a shared 440 SNP haplotype, and its frequency in the general Arab population is estimated to be <1:123. Our findings confirm loss of BMPER function as a cause of axial versus appendicular skeletal defects, and suggest that less deleterious mutations may be involved in milder axial skeleton abnormalities. PMID:21990102

Ben-Neriah, Ziva; Michaelson-Cohen, Rachel; Inbar-Feigenberg, Michal; Nadjari, Michael; Zeligson, Sharon; Shaag, Avraham; Zenvirt, Shamir; Elpeleg, Orly; Levy-Lahad, Ephrat

2011-10-11

362

ECOLOGICAL EFFECTS OF COOLING WATER DISCHARGE ON HYDROLITTORAL EPILITHIC DIATOM COMMUNITIES IN THE NORTHERN BALTIC SEA  

Microsoft Academic Search

The discharge of brackish cooling water from a nuclear power plant on the Swedish Baltic coast has major effects on the species composition, biomass and seasonal variation of epilithic diatom communities in the hydrolittoral zone. Greatest effects occur in winter and early spring, when enormous diatom blooms are caused by the higher water temperatures (6–10°C above natural level) and by

P. J. M. Snoeijs

1989-01-01

363

Effects on the ecological integrity of a soft-bottom habitat from a trawling disturbance  

Microsoft Academic Search

The effects of trawling disturbance on a soft-sediment system were investigated with a manipulative field experiment in an area that had been closed to shrimp trawling activities for 20 years. The area was also chosen for its weak natural physical agents i.e. no scouring of sediments by storm events or tidal flow, allowing a quantitative assessment of the effects of

Pamela J. Sparks-McConkey; Les Watling

2001-01-01

364

Identifying Hazards in Complex Ecological Systems. Part 2: Infection Modes and Effects Analysis for Biological Invasions  

Microsoft Academic Search

This paper describes a rigorous and systematic hazard analysis, called infection modes and effects analysis (named after its industrial counterpart failure modes and effect analysis (FMEA)), which was used to investigate the potential spread of marine organisms by human vectors. The analysis was conducted using small craft as a model system and implemented through nine workshops targeted at owners and

Keith R. Hayes

2002-01-01

365

The Mozart Effect: Musical Phenomenon or Musical Preference? A More Ecologically Valid Reconsideration  

ERIC Educational Resources Information Center

The "Mozart effect" is the reported phenomenon of increased spatial abilities after listening to that composer's music. However, subsequent research suggests that the Mozart effect may be an artifactual consequence of heightened arousal and mood rather than the music of Mozart per se (e.g., Thompson, Schellenberg, & Husain, 2001). The present…

Cassity, Hope Daniels; Henley, Tracy B.; Markley, Robert P.

2007-01-01

366

Ecological effects of feral biofuel crops in constructed oak savannah communities - June 2012  

EPA Science Inventory

The effects of elevated temperatures and drought on constructed oak savannahs were studied to determine the interactive effects of potentially invasive feral biofuel species and climate change on native grassland communities. A total of 12 sunlit mesocosm were used. Each mesoco...

367

Geographical Distribution of Adolescent Body Height with Respect to Effective Day Length in Japan: An Ecological Analysis  

PubMed Central

The height of Japanese youth raised in the northern region tends to be greater than that of youth raised in the southern region; therefore, a geographical gradient in youth body height exists. Although this gradient has existed for about 100 years, the reasons for it remain unclear. Consideration of the nutritional improvement, economic growth, and intense migration that has occurred in this period indicates that it is probably the result of environmental rather than nutritional or genetic factors. To identify possible environmental factors, ecological analysis of prefecture-level data on the body size of 8- to 17-year-old youth averaged over a 13-year period (1996 to 2008) and Japanese mesh climatic data on the climatic variables of temperature, solar radiation, and effective day length (duration of photoperiod exceeding the threshold of light intensity) was performed. The geographical distribution of the standardized height of Japanese adolescents was found to be inversely correlated to a great extent with the distribution of effective day length at a light intensity greater than 4000 lx. The results of multiple regression analysis of effective day length, temperature, and weight (as an index of food intake) indicated that a combination of effective day length and weight was statistically significant as predictors of height in early adolescence; however, only effective day length was statistically significant as a predictor of height in late adolescence. Day length may affect height by affecting the secretion of melatonin, a hormone that inhibits sexual and skeletal maturation, which in turn induces increases in height. By affecting melatonin production, regional differences in the duration of the photoperiod may lead to regional differences in height. Exposure to light intensity greater than 4000 lx appears to be the threshold at which light intensity begins to affect the melatonin secretion of humans who spend much of their time indoors.

Yokoya, Masana; Shimizu, Hideyasu; Higuchi, Yukito

2012-01-01

368

Hydrothermal carbonization of biomass residues: mass spectrometric characterization for ecological effects in the soil-plant system.  

PubMed

Hydrochars, technically manufactured by hydrothermal carbonization (HTC) of biomass residues, are recently tested in high numbers for their suitability as feedstock for bioenergy production, the bioproduct industry, and as long-term carbon storage in soil, but ecological effects in the soil-plant system are not sufficiently known. Therefore, we investigated the influence of different biomass residues and process duration on the molecular composition of hydrochars, and how hydrochar addition to soils affected the germination of spring barley ( L.) seeds. Samples from biomass residues and the corresponding hydrochars were analyzed by pyrolysis-field ionization mass spectrometry (Py-FIMS) and gaseous emissions from the germination experiments with different soil-hydrochar mixtures by gas chromatography/mass spectrometry (GC/MS). The molecular-level characterization of various hydrochars by Py-FIMS clearly showed that the kind of biomass residue influenced the chemical composition of the corresponding hydrochars more strongly than the process duration. In addition to various detected possible toxic substances, two independent mass spectrometric methods (Py-FIMS and GC/MS) indicated long C-chain aliphatic compounds which are typically degraded to the C-unit ethylene that can evoke phytotoxic effects in high concentrations. This showed for the first time possible chemical compounds to explain toxic effects of hydrochars on plant growth. It is concluded that the HTC process did not result in a consistent product with defined chemical composition. Furthermore, possible toxic effects urgently need to be investigated for each individual hydrochar to assess effects on the soil organic matter composition and the soil biota before hydrochar applications as an amendment on agricultural soils. PMID:23673755

Jandl, Gerald; Eckhardt, Kai-Uwe; Bargmann, Inge; Kücke, Martin; Greef, Jörg-Michael; Knicker, Heike; Leinweber, Peter

369

Ecology Explorers  

NSDL National Science Digital Library

This K-12 education program gives students (especially in the Phoenix, AZ area) opportunities to take part in real scientific research led by Central Arizona - Phoenix Long-Term Ecological Research (CAP LTER) scientists. Using this site, students learn data collection techniques used by scientists, called protocols. They collect initial data, using the protocols they have learned, and apply it in looking for patterns at their own research site (schoolyard or backyard). Their data can also be shared with other researchers and school kids to see what patterns in nature exist across the Phoenix metropolitan area. Their own hypotheses and experiments will lead to a better understanding of why those patterns exist and will help them to understand what real scientists are doing in their laboratories. Topics covered include arthropods, beetles, seeds, birds and vegetation.

370

In vitro assessment of reproductive toxicity of cigarette smoke and deleterious consequences of maternal exposure to its constituents.  

PubMed

Cigarette smoke is known to be a serious health risk factor and considered reproductively toxic. In the current study, we investigated whether constituents of cigarette smoke, pyrazine, 2-ethylpyridine, and 3-ethylpyridine, adversely affect reproductive functioning such as oocyte maturation and sperm capacitation. Our findings indicated that three smoke components were involved in retardation of oocyte maturation in a dose-dependent manner and the lowest-observed-adverse-effect level (LOAEL) was determined to be 10(-10)M. However, individual smoke components administrated at the LOAEL did not attenuate oocyte maturation, demonstrating that all three toxicants were equally required for the observed growth impairment. When exposed to all three components at 10(-10)M during in vitro capacitation, murine sperm lost forward progression and were unable to show adequate hyperactivation, which is indicative of the incompletion of the capacitation process. Only sperm administrated with 3-ethylpyridine alone showed significant reduction in capacitation status, suggesting the chemical is the one responsible for disrupting sperm capacitation. Taken together, this is the first report that documents the effect of cigarette smoke components on oocyte maturation and sperm capacitation. The present findings demonstrate the adverse effects of smoke constituents of mammalian reproduction and the differences in sensitivity to smoke components between male and female gametes. Since both processes take place in the female reproductive system, our data provide new insights into deleterious consequences of maternal exposure to cigarette smoke. PMID:23096353

Wu, Shao-Chin; Liu, Min

2012-01-01

371

Valuation of ecological resources  

SciTech Connect

Ecological resources are resources that have functional value to ecosystems. Frequently, these functions are overlooked in terms of the value they provide to humans. Environmental economics is in search of an appropriate analysis framework for such resources. In such a framework, it is essential to distinguish between two related subsets of information: (1) ecological processes that have intrinsic value to natural ecosystems; and (2) ecological functions that are values by humans. The present study addresses these concerns by identifying a habitat that is being displaced by development, and by measuring the human and ecological values associated with the ecological resources in that habitat. It is also essential to determine which functions are mutually exclusive and which are, in effect, complementary or products of joint production. The authors apply several resource valuation tools, including contingent valuation methodology (CVM), travel cost methodology (TCM), and hedonic damage-pricing (HDP). One way to derive upper-limit values for more difficult-to-value functions is through the use of human analogs, because human-engineered systems are relatively inefficient at supplying the desired services when compared with natural systems. Where data on the relative efficiencies of natural systems and human analogs exist, it is possible to adjust the costs of providing the human analog by the relative efficiency of the natural system to obtain a more realistic value of the function under consideration. The authors demonstrate this approach in an environmental economic case study of the environmental services rendered by shrub-steppe habitats of Benton County, Washington State.

Scott, M.J.; Bilyard, G.R.; Link, S.O.; Ricci, P.F.; Seely, H.E.; Ulibarri, C.A.; Westerdahl, H.E.

1995-04-01

372

The ecological effects of a herbicide-insecticide mixture on an experimental freshwater ecosystem.  

PubMed

The effects of a co-occurring insecticide-herbicide mixture were evaluated using model ecosystems (microcosms) in the laboratory. Microcosms dosed with a high concentration (10 ?g/L) of the insecticide terbufos, alone and as a mixture with the herbicide atrazine (25 ?g/L), exhibited community level effects attributed to the elimination and decline of invertebrate populations, and also indirect effects. There were no community level effects at a lower concentration of terbufos (0.1 ?g/L) alone or in a mixture with atrazine, although delayed population effects were observed. Female chironomids also emerged later and those from terbufos-only microcosms were smaller. Exposure to atrazine alone was also associated with lower abundances of cladocerans and reduced emergence of chironomids. The risk posed by atrazine is low and is unlikely to exacerbate the effects of terbufos. Nevertheless, the population-level effects highlight that terbufos poses a potential risk to aquatic ecosystems, regardless of whether atrazine is also present. PMID:23078997

Choung, Catherine B; Hyne, Ross V; Stevens, Mark M; Hose, Grant C

2012-10-16

373

METHODS FOR DETERMINING EXPOSURE TO AND POTENTIAL ECOLOGICAL EFFECTS OF GENE FLOW FROM GENETICALLY MODIFIED CROPS TO COMPATIBLE RELATIVES  

EPA Science Inventory

SCIENCE QUESTIONS: -Does gene flow occur from genetically modified (GM) crop plants to compatible plants? -How can it be measured? -Are there ecological consequences of GM crop gene flow to plant communities? RESEARCH: The objectives ...

374

Effects of stream topology on ecological community results from neutral models  

EPA Science Inventory

While neutral theory and models have stimulated considerable literature, less well investigated is the effect of topology on neutral metacommunity model simulations. We implemented a neutral metacommunity model using two different stream network topologies, a widely branched netw...

375

The effects of exposure to environmental factors on Heart Rate Variability: An ecological perspective.  

PubMed

The impact of human exposure to environmental factors on Heart Rate Variability (HRV) was examined in the urban space of Tel-Aviv-Jaffa. Four environmental factors were investigated: thermal and social loads; CO concentrations and noise. Levels of HRV are explained mainly by subjective social stresses, noise and CO. The most interesting result is the fact that while subjective social stress and noise increase HRV, low levels of CO are reducing HRV to some extent moderating the impact of subjective social stress and noise. Beyond the poisoning effect of CO and the fact that extremely low levels of HRV associated with high dozes of CO increase risk for life, low levels of CO may have a narcotic effect, as it is measured by HRV. The effects of thermal loads on HRV are negligible probably due to the use of behavioral means in order to neutralize heat and cold effects. PMID:23477780

Schnell, Izhak; Potchter, Oded; Epstein, Yoram; Yaakov, Yaron; Hermesh, Hagai; Brenner, Shmuel; Tirosh, Emanuel

2013-03-09

376

Ecological Effects of Spring and Late Summer Applications of Lambda-Cyhalothrin on Freshwater Microcosms  

Microsoft Academic Search

The aim of the study was to compare the effects of the pyrethroid insecticide lambda-cyhalothrin (treated at 10, 25, 50, 100,\\u000a 250 ng active ingredient a.i.\\/L) on a drainage ditch ecosystem in spring and late summer. Microcosms (water volume approximately\\u000a 430 L) were established using enclosures in a 50-cm–deep experimental ditch system containing communities typical of macrophyte-dominated\\u000a freshwater ecosystems. Effects

R. P. A. Van Wijngaarden; T. C. M. Brock; P. J. van den Brink; R. Gylstra; S. J. Maund

2006-01-01

377

Bottom-up effects of geologic parent material through ecological interaction webs  

NASA Astrophysics Data System (ADS)

Community ecologists study the interactions between species to understand what controls the distribution and abundance of different populations. Communities are thus portrayed as "interaction webs", in which different species exert reciprocal pressures on each other. In the case of one population being a resource for which another population is the consumer (i.e. food-web), reciprocal pressures are commonly referred to as "bottom-up" vs. "top-down" effects. The starting point for studying bottom-up effects is usually the vegetation (primary producers), and its end-point the decomposer community responsible for breaking down detrital matter from each trophic level. In my presentation, I will present results from three former graduate students, to argue that the starting point for studying bottom-up effects should be the geologic parent material (GPM), whose importance has often been overlooked by community ecologists. For example, our data show that GPM had a stronger effect on forest floor nutrient budgets than the identity or successional stage of the vegetation. Likewise, GPM had a strong effect on the structure of forest floor microbial communities, as well as their resistance to, and resilience from, disturbance. GPM also had a significant effect on the richness and diversity of understory plant communities from similar forest stands. Finally, we present evidence that soil fertility controls the resistance and tolerance of certain plant species to selective browsing, thereby affecting the composition of the dominant plant cover and the feeding patterns of large herbivores.

Bradley, R.

2012-04-01

378

Community ecology of invasions: direct and indirect effects of multiple invasive species on aquatic communities.  

PubMed

With many ecosystems now supporting multiple nonnative species from different trophic levels, it can be challenging to disentangle the net effects of invaders within a community context. Here, we combined wetland surveys with a mesocosm experiment to examine the individual and combined effects of nonnative fish predators and nonnative bullfrogs on aquatic communities. Among 139 wetlands, nonnative fish (bass, sunfish, and mosquitofish) negatively influenced the probability of occupancy of Pacific treefrogs (Pseudacris regilla), but neither invader correlated strongly with occupancy by California newts (Taricha torosa), western toads (Anaxyrus boreas), or California red-legged frogs (Rana draytonii). In mesocosms, mosquitofish dramatically reduced the abundance of zooplankton and palatable amphibian larvae (P. regilla and T. torosa), leading to increases in nutrient concentrations and phytoplankton (through loss of zooplankton), and rapid growth of unpalatable toad larvae (through competitive release). Bullfrog larvae reduced the growth of native anurans but had no effect on survival. Despite strong effects on natives, invaders did not negatively influence one another, and their combined effects were additive. Our results highlight how the net effects of multiple nonnative species depend on the trophic level of each invader, the form and magnitude of invader interactions, and the traits of native community members. PMID:22834365

Preston, Daniel L; Henderson, Jeremy S; Johnson, Pieter T J

2012-06-01

379

Ecology and Asthma  

Microsoft Academic Search

\\u000a Ecology is the study of patterns of relationships between organisms and their environment (Green et al. 2001). When applied\\u000a to asthma, investigators have taken several different approaches to the “environment,” usually by studying the effect of the\\u000a environment on the “organism” defined as people with asthma (Harper 2004; Hart and Whitehead 1990; Stoloff 2000; Lanphear\\u000a et al. 2001; Gold and

Barbara P. Yawn

380

The effect of physical drivers on ecosystem indices derived from ecological network analysis: Comparison across estuarine ecosystems  

NASA Astrophysics Data System (ADS)

The structure and function of estuarine food webs change in response to both natural and anthropogenic stresses. The construction of quantitative food webs and their analysis by means of Ecological Network Analysis provides outputs that have been used in many studies to assess system development, stress, robustness, resilience and maturity. Here we attempt to relate to the physical characteristics of the environment, ecosystem indices derived from Ecological Network Analysis. Ten models of food webs were gathered, across a selection of soft-bottom estuaries representative of a large morphological and hydrodynamic diversity, from wave-dominated to mixed energy tide-dominated systems. The selection allowed the comparison of their derived Ecological Network Analysis indices, because of similarities of accuracy in the representation of detritus and bacteria, and because models took into account all trophic levels up to top-predators. In order to obtain comparable physical characteristics, global models were used for a homogeneous description of tide and tidal prisms. Spearman correlations, hierarchical ascendant clustering and Redundancy Analysis were applied to examine the relationship between Ecological Network Analysis indices and physical characteristics. The set of four physical variables selected (catchment area, tidal range at neap tide, index of tide-wave domination and latitude in absolute value) explained 67% of the structure of the Ecological Network Analysis indices. This implies that the physical forcing related to climate, hydrodynamics and morphology is essential for determining the ecological emergent properties of the food web. In the European policy context of determining the 'good ecological status' of coastal ecosystems, it implies that the use of Ecological Network Analysis indices for basing the determination of operational indicators should be done, taking into account this context of a strong influence of physical factors.

Niquil, Nathalie; Chaumillon, Eric; Johnson, Galen A.; Bertin, Xavier; Grami, Boutheina; David, Valérie; Bacher, Cédric; Asmus, Harald; Baird, Daniel; Asmus, Ragnhild

2012-08-01

381

Current challenges in contaminant effects monitoring: Multiple stressors and ecological significance  

SciTech Connect

Aquatic ecosystems are complex entities that are controlled and regulated by a multitude of physicochemical and biological processes. In addition, aquatic organisms experience a variety of natural and man-induced stressors, both of which vary spatially and temporally. The high variability in environmental factors combined with synergistic and cumulative interactions of these factors in aquatic ecosystems complicate the interpretation and evaluation of the effects of contaminant-related stressors on organisms. With this in mind, some main challenges facing those concerned with assessing the effects of environmental contaminants on organisms are (1) the influence of multiple stressors on stress responses in biological systems, (2) determining causal relationships between various levels of biological response to stressors, and (3) identifying early warning indicators or measures of organism impairment that have biological significance before irreversible or serious disability occurs. In all these areas, the health of biological systems (from the individual level to the population and community levels) has as its basis the physiological performance of the organism. Therefore, aspects of contaminant effects monitoring which include physiological measures of health should not only be utilized as measures of deviations from normal function, but should also be applied in the larger context of helping to understand multiple stressor effects, causal relationships between different levels of biological response, and early warning indicators of biologically significant effects.

Adams, S.M.; Ham, K.D.

1996-09-01

382

Ecological effects of pipeline construction through deciduous forested wetlands, Midland County, Michigan. Topical report, October 1990--August 1992  

SciTech Connect

This study is designed to record vegetational changes induced by the construction of a large-diameter gas pipeline through deciduous forested wetlands. Two second-growth wetland sites mapped Lenawee soils were selected in Midland County, Michigan: Site 1, a younger stand subjected to recent selective logging, and Site 2, a more mature stand. The collection of ecological data to analyze plant succession on the right-of-way (ROW) and the effects of the developing ROW plant communities on adjacent forest communities was initiated in 1989. Cover class estimates were made for understory and ROW plant species on the basis of 1 {times} 1{minus}m quadrats. Individual stem diameters and species counts were recorded for overstory plants in 10{minus}m quadrats. Although long-term studies have not been completed, firm baseline data were established for comparative analyses with future sampling. Current data indicate that vegetation became well-established on the ROW within one year and subsequently increased in coverage. About 65% of the species were wetland indicators, and the dominants included seeded and natural invading species; nevertheless, some elements of the original flora regenerated and persist. The plants of the ecotone understories of both sites changed from their original composition as a result of the installation of the gas pipeline. Although some forest species persist at both sites, the ecotone of Site I was influenced more by the seeded species, whereas the natural invaders were more important at Site 2.

Rastorfer, J.R. [Chicago State Univ., IL (United States). Dept. of Biological Sciences; Van Dyke, G.D.; Zellmer, S.D.; Wilkey, P.L. [Argonne National Lab., IL (United States)

1995-04-01

383

Sustainability Evaluation of the Grain for Green Project: From Local People's Responses to Ecological Effectiveness in Wolong Nature Reserve  

NASA Astrophysics Data System (ADS)

This article examines the sustainability of the Grain for Green Project in the Wolong Nature Reserve. Pertinent data were collected through a questionnaire survey and a spatial analysis of reforested lands. The study results identified four critical issues that may influence the sustainability of the project in the study area. The first issue is concerned with the project’s impacts on local sustenance. Because local grain consumption depends greatly on compensation awarded by the project, the potential for sustainability of the project is compromised. The second issue is that the project causes negative effects on local incomes in the Wolong Nature Reserve, which may undermine local economic prospects. The third issue is that the project failed to deliver suitable habitat for the giant panda, although two of the suitability requirements that deal with landform features were met. Lastly, the project neglects great differences among geographical areas in the country, providing the same compensation and length of compensation period to all participants. Appropriate compensation mechanisms should be established and adapted to local economic, environmental, and social conditions. In managing nature reserves and moving toward sustainability, ensuring all aspects of local socioeconomic and ecological/environmental issues are properly addressed is a real challenge. Based on our study, some recommendations for improving sustainability of the project are given.

Xu, Jian-Ying; Chen, Li-Ding; Lu, Yi-He; Fu, Bo-Jie

2007-07-01

384

The effect of some ecological factors on the intestinal parasite loads of the Asian elephant (Elephas maximus) in southern India.  

PubMed

Some ecological factors that might potentially influence intestinal parasite loads in the Asian elephant (Elephas maximus Linn.) were investigated in the Nilgiris, southern India. Fresh dung samples from identified animals were analysed, and the number of eggs/g of dung used as an index of parasite load. Comparisons across seasons and habitats revealed that parasite loads were significantly higher during the dry season than the wet season, but were not different between the dry-deciduous and dry-thorn forests in either season. After accounting for the effect of age on body condition, there was no correlation between body condition, assessed visually using morphological criteria, and parasite load in either season. Individuals of different elephant herds were not characterized by distinct parasite communities in either season. When intra-individual variation was examined, samples collected from the same individual within a day differed significantly in egg densities, while the temporal variation over several weeks or months (within a season) was much less. Egg densities within dung piles were uniform, enabling a simpler collection method henceforth. PMID:12381877

Vidya, T N C; Sukumar, R

2002-09-01

385

The ecological significance of phenology in four different tree species: effects of light and temperature on bud burst.  

PubMed

The process of adaptation is the result of stabilising selection caused by two opposite forces: protection against an unfavourable season (survival adaptation), and effective use of growing resources (capacity adaptation). As plant species have evolved different life strategies based on different trade offs between survival and capacity adaptations, different phenological responses are also expected among species. The aim of this study was to compare budburst responses of two opportunistic species (Betula pubescens, and Salix x smithiana) with that of two long-lived, late successional species (Fagus sylvatica and Tilia cordata) and consider their ecological significance. Thus, we performed a series of experiments whereby temperature and photoperiod were manipulated during dormancy. T. cordata and F. sylvatica showed low rates of budburst, high chilling requirements and responsiveness to light intensity, while B. pubescens and S. x smithiana had high rates of budburst, low chilling requirements and were not affected by light intensity. In addition, budburst in B. pubescens and S. x smithiana was more responsive to high forcing temperatures than in T. cordata and F. sylvatica. These results suggest that the timing of growth onset in B. pubescens and S. x smithiana (opportunistic) is regulated through a less conservative mechanism than in T. cordata and F. sylvatica (long-lived, late successional), and that these species trade a higher risk of frost damage for the opportunity of vigorous growth at the beginning of spring, before canopy closure. This information should be considered when assessing the impacts of climate change on vegetation or developing phenological models. PMID:21113629

Caffarra, Amelia; Donnelly, Alison

2010-11-27

386

Ecology of parasite Sycophilomorpha sp. on Ficus altissima and its effect on the fig-fig wasp mutualism.  

PubMed

Figs and their pollinating wasps are a classic example of an obligate mutualism. In addition, figs are parasitized by a suite of non-mutualistic wasps whose basic ecology is largely undescribed. Sycophilomorpha (subfamily Epichrysomallinae) fig wasps are ovule gallers and the genus contains only 1 described species. An undescribed Sycophilomorpha species parasitized Ficus altissima at Xishuangbana, Southwestern China. The wasp was observed ovipositing on the tiny immature figs that were still concealed beneath the involucral bracts. A Sycophilomorpha wasp oviposited on more than 1 fig and spent long time-periods to lay large clutches on a single fig. The wasps naturally occurred on all 7 sampled trees, but the occurrence of wasps was significantly different among trees, crops and months. These wasps were able to prevent unpollinated figs from being aborted, and their offspring were able to develop in the figs that otherwise had no pollinator wasps or seeds. The Sycophilomorpha wasp had a detrimental effect on the fig-fig wasp mutualism. Figs in which Sycophilomorpha wasps were present, produced significantly fewer seeds, pollinators and cheaters. However, the abundance of Sycophilomorpha in a fig was only significantly negatively correlated with pollinator production and not seed or cheater production. Our study illustrates a previously unknown fig wasp niche and expands our understanding of factors that can affect the fig-fig wasp interaction. PMID:20561397

Peng, Y Q; Zhao, J B; Harrison, R D; Yang, D R

2010-06-21

387

Ecological study of effect of breast feeding on infant mortality in Latin America  

Microsoft Academic Search

Objective To estimate the effect of exclusive breast feeding and partial breast feeding on infant mortality from diarrhoeal disease and acute respiratory infections in Latin America. Design Attributable fraction analysis of national data on infant mortality and breast feeding. Setting Latin America and the Caribbean. Main outcome measures Mortality from diarrhoeal disease and acute respiratory infections and nationally representative breastfeeding

Mercedes de OnÌs

2001-01-01

388

RESEARCH AT THE GULF ECOLOGY DIVISION ON THE EFFECTS OF LOW DISSOLVED OXYGEN ON ESTUARINE ANIMALS  

EPA Science Inventory

Concerns about hypoxia and its effects on saltwater organisms are increasing as environmental conditions in the inshore and nearshore marine environments are better understood. Along the Gulf of Mexico coast, periods of very low dissolved oxygen (D.O.) concentrations have been re...

389

ACIDITY, NUTRIENTS, AND MINERALS IN ATMOSPHERIC PRECIPITATION OVER FLORIDA: DEPOSITION PATTERNS, MECHANISMS, AND ECOLOGICAL EFFECTS  

EPA Science Inventory

The results of this project can be summarized into the following conclusions, according to the three major phases of the project: (1) atmospheric deposition of nutrients and minerals; (2) the spatial and temporal distribution of rainfall acidity in Florida; and (3) the effects of...

390

Topological keystone species in ecological interaction networks: Considering link quality and non-trophic effects  

Microsoft Academic Search

There is increasing evidence that non-trophic interspecific interactions play an at least as important role in community dynamics as trophic relationships. More and more studies on pollination, mutualism and facilitation are published but these effects are interpreted more like alternative explanations than being synthesized with results of trophic analyses. Here, we construct and analyze the interaction web of the well-studied

Vera Vasas; Ferenc Jordán

2006-01-01

391

Ecological and statistical evaluation of effects of pesticides in freshwater model ecosystems  

Microsoft Academic Search

Aquatic risk assessment of pesticidesThe first tier in the aquatic risk assessment procedure consists of a comparison between a Predicted Environmental Concentration (PEC) with a No Effect Concentration (NEC). A requirement for registration is that the PEC should not exceed the NEC. The NEC is calculated from the toxicity of the pesticide for defined standard test species (viz. algae Daphnia

Brink van den P. J

1999-01-01

392

COMPARATIVE EFFECTS OF LEAFY SPURGE ON RUMEN BACTERIAL ECOLOGY OF THE BOVINE AND OVINE.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Euphorbia esula (Leafy spurge ;LS), is a forb native to Eurasia and is considered an invasive plant species in the Northern Great Plains. Domesticated species of ruminants including goats and sheep graze leafy spurge with minimal adverse effects; however, cattle avoid areas infested with LS. When...

393

A Three-Level Mixed-Effects Location Scale Model With An Application To Ecological Momentary Assessment (EMA) Data  

PubMed Central

In studies using Ecological Momentary Assessment (EMA), or other intensive longitudinal data collection methods, interest frequently centers on changes in the variances, both within-subjects (WS) and between-subjects (BS). For this, Hedeker et al. (Biometrics 2008; 64: 627-634) developed an extended two-level mixed-effects model that treats observations as being nested within subjects and allows covariates to influence both the WS and BS variance, beyond their influence on means. However, in EMA studies, subjects often provide many responses within and across days. To account for the possible systematic day-to-day variation, we developed a more flexible three-level mixed-effects location scale model that treats observations within days within subjects, and allows covariates to influence the variance at the subject, day, and observation level (over and above their usual effects on means) using a log-linear representation throughout. We provide details of a maximum likelihood (ML) solution and demonstrate how SAS PROC NLMIXED can be used to achieve ML estimates in an alternative parameterization of our proposed three-level model. The accuracy of this approach using NLMIXED was verified by a series of simulation studies. Data from an adolescent mood study using EMA was analyzed to demonstrate this approach. The analyses clearly show the benefit of the proposed three-level model over the existing two-level approach. The proposed model has useful applications in many studies with three-level structures where interest centers on the joint modeling of the mean and variance structure.

Li, Xue; Hedeker, Donald

2013-01-01

394

Effect of heavy metal pollution on mycorrhizal colonization and function: physiological, ecological and applied aspects  

Microsoft Academic Search

High concentrations of heavy metals in soil have an adverse effect on micro-organisms and microbial processes. Among soil\\u000a microorganisms, mycorrhizal fungi are the only ones providing a direct link between soil and roots, and can therefore be of\\u000a great importance in heavy metal availability and toxicity to plants. This review discusses various aspects of the interactions\\u000a between heavy metals and

C. Leyval; K. Turnau; K. Haselwandter

1997-01-01

395

Energy and ecology  

SciTech Connect

The use of any renewable or nonrenewable energy form has ecological and environmental consequences. To comprehend these consequences, we must first understand the technology of each energy form: solar, biomass, coal, petroleum, nuclear, and such alternative energy sources as ocean thermal energy conversion, geothermal, wind, hydroelectric, ocean tidal, and ocean wave. The author examines the ecological principles, the food chains, and the effects of physical factors, biogeochemical cycles, and population growth. Separate chapters deal with the atmosphere, individual energy sources, carbon dioxide and climate change, electric power generation, and alternative energy sources. Intended for the lay reader, the book offers a multi-disciplinary awareness of the dangers of energy misuse and overexploitation while encouraging a sensible, sensitive stewardship. 234 references, 106 figures, 23 tables.

Gates, D.M.

1985-01-01

396

Antidepressant Medication and Executive Dysfunction: A Deleterious Interaction in Late-Life Depression  

PubMed Central

Objectives To determine whether there is differential response to placebo or citalopram among older patients with and without deficient response inhibition. Design 8-week, double-blind, placebo controlled trial. Setting Outpatient psychiatry. Participants Unipolar depressed patients aged 75 years and older. Intervention citalopram (20–40 mg/d) or placebo pill. Measurements Baseline Stroop Color Word Test and weekly 24-item Hamilton Rating Scale for Depression assessments. Results Citalopram treated patients with deficient response inhibition did significantly worse than placebo treated patients with deficient response inhibition. Conversely, citalopram treated patients without deficient response inhibition did significantly better than placebo treated patients without deficient response inhibition. Conclusion Patients with late-life depression and deficient response inhibition respond worse to SSRI than placebo. These findings suggest that there may be a deleterious interaction between deficient response inhibition and antidepressant medication in late-life depression and that the mechanism of SSRI and placebo response is different.

Sneed, Joel R.; Culang, Michelle E.; Keilp, John G.; Rutherford, Bret R.; Devanand, D. P.; Roose, Steven P.

2009-01-01

397

Taking Ecological Function Seriously: Soil Microbial Communities Can Obviate Allelopathic Effects of Released Metabolites  

PubMed Central

Background Allelopathy (negative, plant-plant chemical interactions) has been largely studied as an autecological process, often assuming simplistic associations between pairs of isolated species. The growth inhibition of a species in filter paper bioassay enriched with a single chemical is commonly interpreted as evidence of an allelopathic interaction, but for some of these putative examples of allelopathy, the results have not been verifiable in more natural settings with plants growing in soil. Methodology/Principal findings On the basis of filter paper bioassay, a recent study established allelopathic effects of m-tyrosine, a component of root exudates of Festuca rubra ssp. commutata. We re-examined the allelopathic effects of m-tyrosine to understand its dynamics in soil environment. Allelopathic potential of m-tyrosine with filter paper and soil (non-sterile or sterile) bioassays was studied using Lactuca sativa, Phalaris minor and Bambusa arundinacea as assay species. Experimental application of m-tyrosine to non-sterile and sterile soil revealed the impact of soil microbial communities in determining the soil concentration of m-tyrosine and growth responses. Conclusions/Significance Here, we show that the allelopathic effects of m-tyrosine, which could be seen in sterilized soil with particular plant species were significantly diminished when non-sterile soil was used, which points to an important role for rhizosphere-specific and bulk soil microbial activity in determining the outcome of this allelopathic interaction. Our data show that the amounts of m-tyrosine required for root growth inhibition were higher than what would normally be found in F. rubra ssp. commutata rhizosphere. We hope that our study will motivate researchers to integrate the role of soil microbial communities in bioassays in allelopathic research so that its importance in plant-plant competitive interactions can be thoroughly evaluated.

Kaur, Surinder; Baldwin, Ian T.; Inderjit

2009-01-01

398

Experimental terrestrial soil-core microcosm test protocol. A method for measuring the potential ecological effects, fate, and transport of chemicals in terrestrial ecosystems  

SciTech Connect

In order to protect the environment properly and have a realistic appraisal of how a chemical will act in the environment, tests of ecological effects and chemical fate must be performed on complex assemblages of biotic and abiotic components (i.e., microcosms) as well as single species. This protocol is one which could be added to a series of tests recently developed as guidelines for Section 4 of the Toxic Substances Control Act (P.L. 94-469; U.S.C., Section 2601-2629). The terrestrial soil-core microcosm is designed to supply site-specific and possibly regional information on the probable chemical fate and ecological effects resulting from release of a chemical substance to a terrestrial ecosystem. The EPA will use the data resulting from this test system to compare the potential hazards of a chemical with others that have been previously evaluated.

Van Voris, P.; Tolle, D.A.; Arthur, M.F.

1985-06-01

399

Effects of an Antibacterial Soap on the Ecology of Aerobic Bacterial Flora of Human Skin  

PubMed Central

The effects of ad lib use of an antibacterial soap containing 1.0% trichlorocarbanilide and 0.5% trifluoromethyldichlorocarbanilide on the bacterial flora of six skin sites of 132 subjects were measured by comparison with the flora of 93 control subjects who avoided the use of topical antibacterials. Each subject was examined once. The test soap produced significant reductions in geometric mean counts of the total aerobic flora on the back, chest, forearm, calf, and foot; counts were also reduced in the axilla, but not to a significant extent. The overall reduction by the test soap on all sites was 62% (P < 0.001). Neither age nor sex influenced the effect of the soap on the flora. The antibacterial soap also reduced the prevalence of Staphylococcus aureus on the skin, mostly by virtually eliminating it from areas other than the axilla. Partial inhibition of the gram-positive flora was not accompanied by an increase in gram-negative species. The latter were found principally in the axilla; Klebsiella pneumoniae and Enterobacter aerogenes were the species most frequently found.

Voss, J. G.

1975-01-01

400

Ecological effects of a deodorant and a plain soap upon human skin bacteria.  

PubMed Central

The effects of a commercial trichlorocarbanilide-containing deodorant soap and a commercial plain soap upon the cutaneous flora of individuals were compared. Using a cross-over design, 21 volunteers (10 women and 11 men) washed their forearms at least once a day with one soap for 3 weeks and then switched soaps for another 4 weeks use. By analysis of variance no significant difference in total colony counts was noted among individuals in their use of the two soaps. With the exception of individual variation, neither sequence of use, sex, nor any combination was influential. However, in 20 of 21 subjects an alteration in the composition of skin flora was observed. The deodorant soap, which in six cases increased total flora, tended to reduce or eliminate diphtheroids in 12 to 17 carriers (71%). Fewer kinds of bacteria were also noted. More Staphylococcus epidermidis was seen with the plain soap, but washing with the deodorant soap seemed to favour Acinetobacter calcoaceticus and Micrococcus luteus. The impact of this alteration and the use of total counts to measure effectiveness of deodorant soaps were brought into question.

Bibel, D. J.

1977-01-01

401

Excretion of enrofloxacin in pigs and its effect on ecological environment.  

PubMed

The concentration of enrofloxacin and its metabolite, ciprofloxacin, in feces and urines were investigated in healthy pigs after oral administration (p.o.) of a single dose of 5.0mg/kgbw and an indoor soil model was set to study the effects of enrofloxacin and ciprofloxacin through biological and chemical metrics including changes to edaphon, edaphic ammonification and nitrification and the soil bacterial community. The results showed that the concentrations of entofloxacin and ciprofloxacin in feces and urines fluctuated, the maximum concentrations of enrofloxacin and ciprofloxacin in the urine were 22.74 and 48.04?g/ml, respectively, 24.68 and 30.98?g/g in the feces, respectively. The effect of enrofloxacin and ciprofloxacin on edaphon, edaphic ammonification and nitrification and the soil bacterial community differed at different time points. And the model can be used to evaluate environmental safety of enrofloxacin and develop possible procedures for the safe handling and utilization of animal excrement. PMID:21791374

Zhou, Xiujin; Chen, Chaoxi; Yue, Lei; Sun, Yongxue; Ding, Huanzhong; Liu, Yahong

2008-06-08

402

Respiratory and mental health effects of wildfires: an ecological study in Galician municipalities (north-west Spain)  

PubMed Central

Background During the summer of 2006, a wave of wildfires struck Galicia (north-west Spain), giving rise to a disaster situation in which a great deal of the territory was destroyed. Unlike other occasions, the wildfires in this case also threatened farms, houses and even human lives, with the result that the perception of disaster and helplessness was the most acute experienced in recent years. This study sought to analyse the respiratory and mental health effects of the August-2006 fires, using consumption of anxiolytics-hypnotics and drugs for obstructive airway diseases as indicators. Methods We conducted an analytical, ecological geographical- and temporal-cluster study, using municipality-month as the study unit. The independent variable was exposure to wildfires in August 2006, with municipalities thus being classified into the following three categories: no exposure; medium exposure; and high exposure. Dependent variables were: (1) anxiolytics-hypnotics; and (2) drugs for obstructive airway diseases consumption. These variables were calculated for the two 12-month periods before and after August 2006. Additive models for time series were used for statistical analysis purposes. Results The results revealed a higher consumption of drugs for obstructive airway diseases among pensioners during the months following the wildfires, in municipalities affected versus those unaffected by fire. In terms of consumption of anxiolytics-hypnotics, the results showed a significant increase among men among men overall -pensioners and non-pensioners- in fire-affected municipalities. Conclusions Our study indicates that wildfires have a significant effect on population health. The coherence of these results suggests that drug utilisation research is a useful tool for studying morbidity associated with environmental incidents.

2011-01-01

403

Great Lakes management: Ecological factors  

NASA Astrophysics Data System (ADS)

Although attempts to improve the quality of the Great Lakes generally focus on chemical pollution, other factors are important and should be considered Ecological factors, such as invasion of the lakes by foreign species, habitat changes, overfishing, and random variations in organism populations, are especially influential. Lack of appreciation of the significance of ecological factors stems partly from the inappropriate application of the concept of eutrophication to the Great Lakes. Emphasis on ecological factors is not intended to diminish the seriousness of pollution, but rather to point out that more cost-effective management, as well as more realistic expectations of management efforts by the public, should result from an ecosystem management approach in which ecological factors are carefully considered.

Sonzogni, W. C.; Robertson, A.; Beeton, A. M.

1983-11-01

404

The contemporary paradox of long-term planning for social-ecological change and its effects on the discourse-practice divide: evidence from Southern Africa  

Microsoft Academic Search

The Maloti-Drakensberg Transfrontier Project between South Africa and Lesotho aims to bring about positive social-ecological change in and around the Maloti-Drakensberg mountain ecosystem. To this effect, the project has developed a long-term planning strategy that has to co-ordinate all involved actors – and their actions – until 2028. The paper describes and analyses the run-up to the strategy. By combining

Bram Büscher; Elna de Beer

2011-01-01

405

Relevance and Applicability of a Simple Earthworm Biomarker of Copper Exposure. I. Links to Ecological Effects in a Laboratory Study with Eisenia andrei  

Microsoft Academic Search

A simple earthworm biomarker, neutral-red retention by coelomocyte lysosomes, was measured concurrently with ecological parameters in order to link effects at different levels of biological organization in a laboratory study. Exposure of the earthwormEisenia andreito an increasing range of soil copper concentrations in the laboratory indicated a threshold range for the neutral-red assay at soil copper concentrations between 40 and

Claus Svendsen

1997-01-01

406

MINIMUM INHIBITORY CONCENTRATIONS OF TWO COMMON FOOD PHENOLIC COMPOUNDS AND THEIR EFFECT ON THE MICROBIAL ECOLOGY OF SWINE FECES IN VITRO  

Microsoft Academic Search

Feeding sub-therapeutic levels of antibiotics to livestock has been associated withdevelopment and spread of antibiotic resistant bacteria. The present experiment was conductedto investigate the effect of antibiotic alternatives (caffeic acid, chlorogenic acid, and carbadox)on the microbial ecology of swine feces in vitro.Minimum inhibitory concentrations of caffeic and chlorogenic acids were determined forseveral pathogens using macrobroth and agar dilution techniques. Gram-negative

Jennifer I. Zaffarano

2003-01-01

407

Short-rotation plantations of balsam poplars, aspen and willows on former arable land in the Federal Republic of Germany. III. Soil ecological effects  

Microsoft Academic Search

As part of an interdisciplinary research program, soil ecological effects of short-rotation forestry were studied at three experimental plantations on former arable soils in southern (Abbachhof=ABB), central (Canstein=CAN) and northern (Wildeshausen=WIL) Germany between 1983 and 1996. The methodological approach included a partly factorial fertilization trial with the nutrients N, P, K, Mg and Ca. Representative treatments and plots of those

A Jug; F Makeschin; K. E Rehfuess; C Hofmann-Schielle

1999-01-01

408

Harvesting Effects and Population Ecology of the Buriti Palm ( Mauritia flexuosa L. f., Arecaceae) in the Jalapão Region, Central Brazil 1  

Microsoft Academic Search

Harvesting Effects and Population Ecology of Buriti Palm (Mauritia flexuosa\\u000a L. f., Arecaceae) \\u000a in the Jalapão Region, Central Brazil. Buriti palm is used for several purposes in Jalapão, Brazil, among which harvesting of young leaves has the greatest potential\\u000a impact on palm populations. This work aimed to (i) assess buriti palm uses, (ii) identify experimentally the impacts of young-leaf\\u000a harvesting

Maurício Bonesso Sampaio; Isabel Belloni Schmidt; Isabel Benedetti Figueiredo

2008-01-01

409

Estimates and comparisons of the effects of sampling variation using ‘national’ macroinvertebrate sampling protocols on the precision of metrics used to assess ecological status  

Microsoft Academic Search

The Water Framework Directive (WFD) of the European Union requires all member countries to provide information on the level\\u000a of confidence and precision of results in their river monitoring programmes to assess the ecological status class of river\\u000a sites. As part of the European Union project STAR, the overall effects of sampling variation for a wide range of commonly\\u000a used

Ralph T. Clarke; John Davy-Bowker; Leonard Sandin; Nikolai Friberg; Richard K. Johnson; Barbara Bis

410

Estimates and comparisons of the effects of sampling variation using ‘national’ macroinvertebrate sampling protocols on the precision of metrics used to assess ecological status  

Microsoft Academic Search

The Water Framework Directive (WFD) of the European Union requires all member countries to provide information on the level\\u000a of confidence and precision of results in their river monitoring programmes to assess the ecological status class of river\\u000a sites. As part of the European Union project STAR, the overall effects of sampling variation for a wide range of commonly\\u000a used

Ralph T. Clarke; John Davy-Bowker; Leonard Sandin; Nikolai Friberg; Richard K. Johnson; Barbara Bis

2006-01-01

411

A review on numerous modeling approaches for effective, economical and ecological treatment wetlands.  

PubMed

Constructed wetlands (CWs) for wastewater treatment have evolved substantially over the last decades and have been recognized as an effective means of "green technology" for wastewater treatment. This paper reviews the numerous modeling approaches ranging from simple first-order models to more complex dynamic models of treatment behaviour in CWs. The main objective of the modeling work is to better understand the process in CWs and optimize design criteria. A brief study in this review discusses the efforts taken to describe the process-based model for the efficient removal of pollutants in CWs. Obtaining better insights is essential to understand the hydraulic and biochemical processes in CWs. Currently, employed modeling approaches can be seen in two categories, i.e. "black-box models" and "process-based models". It is evident that future development in wetland technology will depend on improved scientific knowledge of internal treatment mechanisms. PMID:21134712

Kumar, J L G; Zhao, Y Q

2010-12-04

412

The effect on ecological systems of remediation to protect human health.  

PubMed

Environmental remediation of contaminated eco-systems reduces stresses to these ecosystems, including stresses caused by the production, use, and storage of weapons of mass destruction. The effects of these various stressors on humans can be reduced by remediation or by blocking the exposure of humans, but blocking the exposure of resident biota is almost impossible. Remediation may involve trade-offs between reducing a minor risk to public health and increasing risks to workers and ecosystems. Remediation practices such as soil removal disrupt ecosystems, which take decades to recover. Without further human disturbances, and with low levels of exposure to stress-ors, ecosystems can recover from physical disruptions and spills. Remediation to remove negligible risk to humans can destroy delicate ecosystems for very little gain in public health. PMID:17666693

Burger, Joanna

2007-07-31

413

Extremes in ecology: Avoiding the misleading effects of sampling variation in summary analyses  

USGS Publications Warehouse

Surveys such as the North American Breeding Bird Survey (BBS) produce large collections of parameter estimates. One's natural inclination when confronted with lists of parameter estimates is to look for the extreme values: in the BBS, these correspond to the species that appear to have the greatest changes in population size through time. Unfortunately, extreme estimates are liable to correspond to the most poorly estimated parameters. Consequently, the most extreme parameters may not match up with the most extreme parameter estimates. The ranking of parameter values on the basis of their estimates are a difficult statistical problem. We use data from the BBS and simulations to illustrate the potential misleading effects of sampling variation in rankings of parameters. We describe empirical Bayes and constrained empirical Bayes procedures which provide partial solutions to the problem of ranking in the presence of sampling variation.

Link, W. A.; Sauer, J. R.

1996-01-01

414

Effects of waterlogging on seed germination of three Mediterranean oak species: Ecological implications  

NASA Astrophysics Data System (ADS)

Soil water saturation during prolonged periods of time generates a negative impact on nearly all terrestrial plants. In Mediterranean woodlands, precipitation can be very abundant during the wet season, inducing temporary soil waterlogging, coinciding with the seed dispersal and germination time of many species. We investigated the effects of waterlogging on seed germination and early root growth of three coexisting oak species ( Quercus canariensis, Q. suber and Q. pyrenaica), by completely flooding of seeds for various periods of time. The three oak species showed a certain level of tolerance to waterlogging, only being affected those seeds subjected for long periods of submersion (over 30 days). Waterlogging during prolonged periods of time decreased the probability of seed germination in the three oak species, lengthened the time to germination, and hampered root development in two of the studied species. The main differences between oak species occurred in terms of root growth ( Q. canariensis being the less affected, and Q. suber the most); these differential responses could be related to a species rank of waterlogging tolerance. Thus inter-specific differences in germination responses to waterlogging could contribute to explain, at least partially, species habitat and distribution patterns across landscapes. Seed mass also played an important role on different aspects of germination, though its relative importance varied as function of species and waterlogging treatment. The tolerance to stress induced by waterlogging increased with seed mass, but only in the case of Q. canariensis.

Pérez-Ramos, Ignacio M.; Marañón, Teodoro

2009-05-01

415

Effect of increased UV-B on weeds and big worms in a farmland ecological system  

NASA Astrophysics Data System (ADS)

Since the 1970's stratospheric zone attenuation liable for surface UV radiation enhancement has been among the ever-increasing concerns of global climatologists. In recent years, numerous efforts have been undertaken at home and abroad to investigate the effect of enhanced surface UV-B on crops' growth, development and yield formation, achieving a lot of significant fruits and concurrently on field ecosystems. As we know, most of the experiments in the past were conducted in laboratories, including a short-term response on an individual-plant basis. This condition differs consipicuously from yield experiments at the level of an ecosystem with regard to its long-range response. Specifically the degree to which the UV radiation influences non-crop species, which leads to the distortion of the response to UV-B enhancement of crop's population and its ecosystem. As a result, it is necessary to carry out long-range field experiments at an ecosystem's level. This paper aims at the impacts of intensified UV-B upon weeds and large soil worms (i.e., microanimals) in an ecosystem of growing wheat, corn (maize) and spinach together with preliminary investigation of the mechanisms.

Zheng, Youfei; Gao, Wei; Wang, Chuanhai; Xiao, Wei; Zhang, Ronggang

2003-11-01

416

Ecological effects of pipeline construction through deciduous forested wetlands, Midland County, Michigan  

SciTech Connect

Implementation of recent federal and state regulations promulgated to protect wetlands makes information on effects of gas pipeline rights-of-way (ROWs) in wetlands essential to the gas pipeline industry. This study is designed to record vegetational changes induced by the construction of a large-diameter gas pipeline through deciduous forested wetlands. Two second-growth forested wetland sites mapped as Lenawee soils, one mature and one subjected to recent selective logging, were selected in Midland County, Michigan. Changes in the adjacent forest and successional development on the ROW are being documented. Cover-class estimates are being made for understory and ROW plant species using 1 {times}1-m quadrats. Counts are also being made for all woody species with stems < 2 cm in diameter at breast height (dbh) in the same plots used for cover-class estimates. Individual stem diameters and species counts are being recorded for all woody understory and overstory plants with stems {ge}2 cm dbh in 10 {times} 10-m plots. Although analyses of the data have not been completed, preliminary analyses indicate that some destruction of vegetation at the ROW forest edge may have been avoidable during pipeline construction. Rapid regrowth of many native wetland plant species on the ROW occurred because remnants of native vegetation and soil-bearing propagules of existing species survived on the ROW after pipeline construction and seeding operations. 91 refs., 11 figs., 3 tabs.

Zellmer, S.D. (Argonne National Lab., IL (United States)); Rastorfer, J.R. (Chicago State Univ., IL (United States). Dept. of Biological Sciences ANL/CSU Cooperative Herbarium, Chicago, IL (United States)); Van Dyke, G.D. (Trinity Christian Coll., Palos Heights, IL (United States). Dept. of Biology)

1991-07-01

417

[Ecological control effects of Litchi chinensis-Desmodium intortum complex plant ecosystem on litchi pests].  

PubMed

An investigation on the community structure and dynamics of litchi pests and their natural enemies in constructed Litchi chinensis-Desmodium intortum complex plant ecosystem and single L. chinensis ecosystem showed that the total amount of litchi pests in the complex plant ecosystem was 61.27% of that in the single ecosystem in whole year, and only 50.45% in May, the key time for fruit development, which suggested that there was an interaction between D. intortum and L. chinensis. D. intortum and L. chinensis had a few common pests, but many common natural enemies. D. intortum florescence in winter provided shelter and substitutive food for the natural enemies of pests to survive in the extreme environmental conditions in winter. L. chinensis florescence was on the heel of D. intortum florescence, which provided better conditions for the natural enemies to survive and multiply. During florescence and fruit development stages of L. chinensis (from March to June), the predator/prey ratio in complex plant system was 4.22, 2.34, 2.2 and 20.63 times of that in single plant system in March, April, May and June, respectively, indicating the good control effect on pests of L. chinensis. PMID:16689252

Ouyang, Gecheng; Yang, Yueping; Liu, Deguang; Xiong, Jinjun; Huang, Mingdu

2006-01-01

418

Effects of spatial subsidies and habitat structure on the foraging ecology and size of geckos.  

PubMed

While it is well established that ecosystem subsidies--the addition of energy, nutrients, or materials across ecosystem boundaries--can affect consumer abundance, there is less information available on how subsidy levels may affect consumer diet, body condition, trophic position, and resource partitioning among consumer species. There is also little information on whether changes in vegetation structure commonly associated with spatial variation in subsidies may play an important role in driving consumer responses to subsidies. To address these knowledge gaps, we studied changes in abundance, diet, trophic position, size, and body condition of two congeneric gecko species (Lepidodactylus spp.) that coexist in palm dominated and native (hereafter dicot dominated) forests across the Central Pacific. These forests differ strongly both in the amount of marine subsidies that they receive from seabird guano and carcasses, and in the physical structure of the habitat. Contrary to other studies, we found that subsidy level had no impact on the abundance of either gecko species; it also did not have any apparent effects on resource partitioning between species. However, it did affect body size, dietary composition, and trophic position of both species. Geckos in subsidized, dicot forests were larger, had higher body condition and more diverse diets, and occupied a much higher trophic position than geckos found in palm dominated, low subsidy level forests. Both direct variation in subsidy levels and associated changes in habitat structure appear to play a role in driving these responses. These results suggest that variation in subsidy levels may drive important behavioral responses in predators, even when their numerical response is limited. Strong changes in trophic position of consumers also suggest that subsidies may drive increasingly complex food webs, with longer overall food chain length. PMID:22899995

Briggs, Amy A; Young, Hillary S; McCauley, Douglas J; Hathaway, Stacie A; Dirzo, Rodolfo; Fisher, Robert N

2012-08-10

419

The Zebra Mussel Invasion: A Marine Ecological  

Microsoft Academic Search

The Zebra mussel Dreissena polymorpha resembles a marine invertebrate, in its mode of reproduction and dispersal, in its ability to exert strong controls on phytoplankton in the water column, and in its strong keystone effects on benthic communities. I discuss some marine ecological perspectives that might enhance the study of the profound ecological and evolutionary effects of Zebra mussels. (1)

Jeffrey Levinton

1994-01-01

420

Deleterious effects of inhibition of the renin-angiotensin system in neonatal rats  

Microsoft Academic Search

The angiotensin I converting enzyme inhibitor (ACEI) perindopril (2 mg\\/kg body weight), the peripheral vasodilator dihydralazine (DHL) (25 mg\\/kg body weight) or distilled water was given daily from birth to day 14 to neonatal rats. Blood pressure, plasma creatinine, plasma renin activity (PRA), substrate (PRS) and concentration (PRC) and renin content of kidney tissue sections were evaluated on days 14

Marina Charbit; Michèle Déchaux; Isabelle Blazy; Rosa Vargas; Denise Laouari; Danièle Brocart; Mireille Lacoste; Marie Claire Gubler; Charles Sachs

1995-01-01

421

Deleterious Effects of High Concentrations of (-)-Epigallocatechin-3Gallate and Atorvastatin in Mice With Colon Inflammation  

Microsoft Academic Search

Epigallocatechin-3-gallate (EGCG), atorvastatin (ATST), and their combination have been previously shown to inhibit colon carcinogenesis in animal models. We further investigated their inhibitory activities in azoxymethane (AOM) and dextran sulfate sodium (DSS)-treated Balb\\/cJ mice and CD-1 mice in 2 slightly different models. The mice were maintained on the AIN93M diet, or a similar diet containing 0.03%, 0.1%, or 0.3% EGCG;

Fei Guan; Anna B. Liu; Guangxun Li; Zhihong Yang; Yuhai Sun; Chung S. Yang; Jihyeung Ju

2012-01-01

422

NSAID-induced deleterious effects on the proximal and mid small bowel in seronegative spondyloarthropathy patients  

PubMed Central

AIM: To investigate the small bowel of seronegative spondyloarthropathy (SpA) patients in order to ascertain the presence of mucosal lesions. METHODS: Between January 2008 and June 2010, 54 consecutive patients were enrolled and submitted to avideo capsule endoscopy (VCE) examination. History and demographic data were taken, as well as the history of non-steroidal anti-inflammatory drug (NSAID) consumption. After reading each VCE recording, a capsule endoscopy scoring index for small bowel mucosal inflammatory change (Lewis score) was calculated. Statistical analysis of the data was performed. RESULTS: The Lewis score for the whole cohort was 397.73. It was higher in the NSAID consumption subgroup (P = 0.036). The difference in Lewis score between NSAID users and non-users was reproduced for the first and second proximal tertiles of the small bowel, but not for its distal third (P values of 0.036, 0.001 and 0.18, respectively). There was no statistical significant difference between the groups with regard to age or sex of the patients. CONCLUSION: The intestinal inflammatory involvement of SpA patients is more prominent in NSAID users for the proximal/mid small bowel, but not for its distal part.

Rimbas, Mihai; Marinescu, Madalina; Voiosu, Mihail Radu; Baicus, Cristian Rasvan; Caraiola, Simona; Nicolau, Adriana; Nitescu, Doina; Badea, Georgeta Camelia; Parvu, Magda Ileana

2011-01-01

423

Infective Endocarditis Due to Staphylococcus aureus Deleterious Effect of Anticoagulant Therapy  

Microsoft Academic Search

Background: The use of anticoagulant therapy in pa- tients with infective endocarditis (IE) is a controversial issue. Objective: To study the impact of anticoagulant therapy on the clinical outcome, mortality, and cause of death in a series of patients with native and prosthetic left- sided Staphylococcus aureus IE. Methods: This report is based on all consecutive cases of IE diagnosed

Pilar Tornos; Benito Almirante; Sonia Mirabet; Gaieta Permanyer; Albert Pahissa; Jordi Soler-Soler

1999-01-01

424

Deleterious effects of neuronal accumulation of glycogen in flies and mice  

PubMed Central

Under physiological conditions, most neurons keep glycogen synthase (GS) in an inactive form and do not show detectable levels of glycogen. Nevertheless, aberrant glycogen accumulation in neurons is a hallmark of patients suffering from Lafora disease or other polyglucosan disorders. Although these diseases are associated with mutations in genes involved in glycogen metabolism, the role of glycogen accumulation remains elusive. Here, we generated mouse and fly models expressing an active form of GS to force neuronal accumulation of glycogen. We present evidence that the progressive accumulation of glycogen in mouse and Drosophila neurons leads to neuronal loss, locomotion defects and reduced lifespan. Our results highlight glycogen accumulation in neurons as a direct cause of neurodegeneration.

Duran, Jordi; Tevy, Maria Florencia; Garcia-Rocha, Mar; Calbo, Joaquim; Milan, Marco; Guinovart, Joan J

2012-01-01

425

Chocolate: a review of published reports of allergic and other deleterious effects, real or presumed.  

PubMed

Although there are specific contraindications to the ingestion of chocolate by selected individuals, these do not apply to the general population with a frequency that is suggested by the pervasive mistrust of chocolate. These contraindications and mistrusts are reviewed. PMID:152075

Fries, J H

1978-10-01

426

Moderate growth restriction: Deleterious and protective effects on white matter damage  

Microsoft Academic Search

The role for growth restriction in the multifactorial pathophysiology of developing white-matter damage remains debated. We studied rat pups with prenatal growth restriction (GR) induced by unilateral ligation of the uterine artery. Pups with severe GR exhibited white-matter damage that persisted to adulthood [Olivier, P., Baud, O., Evrard, P., Gressens, P.,Verney, C., 2005. Prenatal ischemia and white matter damage in

Paul Olivier; Olivier Baud; Myriam Bouslama; Philippe Evrard; Pierre Gressens; Catherine Verneya

2007-01-01

427

Trimetazidine Reverses Deleterious Effects of Ischemia-Reperfusion in the Isolated Perfused Pig Kidney Model  

Microsoft Academic Search

Background: Delayed graft function has remained an important complication after renal transplantation. Methods: The purpose of this study was to evaluate Euro-Collins (EC) plus trimetazidine (TMZ) in comparison with standard EC solution after 24- or 48-hour cold storage. The normothermic isolated perfused pig kidney technique combined with proton nuclear magnetic spectroscopy was used. Results: The study verified that TMZ plus

Thierry Hauet; Denis Mothes; Jean-Michel Goujon; Thierry Germonville; Jean Claude Caritez; Michel Carretier; Michel Eugene; Jean-Paul Tillement

1998-01-01