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Same Environment (same + environment)
Selected AbstractsContrasting Patch Residence Strategy in Two Species of Sit-and-Wait Foragers Under the Same Environment: A Constraint by Life History?ETHOLOGY, Issue 2 2005Tadashi Miyashita The present study explored the significance of life history constraints on patch residence strategy by using two congeneric web spider species living in the same habitat. Nephila maculata had a large body size but had a shorter developmental period compared with N. clavata, indicating that N. maculata should have a greater foraging efficiency to reach maturity and reproduce. Residence time at web-sites in N. maculata was shorter than that in N. clavata, irrespective of the season. However, supplementation of food to N. maculata increased residence time, suggesting that it searches web-sites with higher prey intake. Investment of web materials, an important trait influencing web relocation frequency, was not greater in N. maculata. In addition, microhabitat and prey size did not differ significantly after controlling for the effect of body size. Because N. maculata needs to attain a large body size in a shorter period of time, this species appears to take a risk of moving patches to seek high quality web-sites. [source] The Florida amphioxus (Cephalochordata) hosts larvae of the tapeworm Acanthobothrium brevissime: natural history, anatomy and taxonomic identification of the parasiteACTA ZOOLOGICA, Issue 1 2009Nicholas D. Holland Abstract Plerocercoid larvae of a tapeworm are frequently found in the hindgut lumen of the Florida amphioxus (Branchiostoma floridae) in central west Florida. About three-quarters of the adult amphioxus are parasitized. On average, each adult amphioxus hosts about five tapeworm larvae. The residence time of the parasites in the amphioxus gut appears to be in the order of several months, which is considerably shorter than the potential lifetime of the host. The living larvae range in length (when fully extended) from 300 to 850 µm and are approximately cone-shaped, tapering to a point posteriorly and bearing a single large sucker anteriorly. Toward the anterior end of the body are four hookless bothridia, each indented by three loculi plus an inconspicuous accessory sucker. The larvae initiate the early stages of hook formation when they are cultured for a few days in urea-saline (mimicking the gut fluid of the definitive host, which is an elasmobranch). The tapeworm larvae are identifiable to genus and species on the basis of correspondences between their nuclear ribosomal DNA genes and those of adult specimens of Acanthobothrium brevissime recovered from the spiral valve of a stingray from the same environment. [source] NMR investigations of subunit c of the ATP synthase from Propionigenium modestum in chloroform/methanol/water (4 : 4 : 1)FEBS JOURNAL, Issue 7 2002Ulrich Matthey The subunit c from the ATP synthase of Propionigenium modestum was studied by NMR in chloroform/methanol/water (4 : 4 : 1). In this solvent, subunit c consists of two helical segments, comprised of residues L5 to I26 and G29 to N82, respectively. On comparing the secondary structure of subunit c from P. modestum in the organic solvent mixture with that in dodecylsulfate micelles several deviations became apparent: in the organic solvent, the interruption of the ,,helical structure within the conserved GXGXGXGX motif was shortened from five to two residues, the prominent interruption of the ,,helical structure in the cystoplasmic loop region was not apparent, and neither was there a break in the ,,helix after the sodium ion-binding Glu65 residue. The folding of subunit c of P. modestum in the organic solvent also deviated from that of Escherichia coli in the same environment, the most important difference being that subunit c of P. modestum did not adopt a stable hairpin structure like subunit c of E. coli. [source] Altered behavioural adaptation in mice with neural corticotrophin-releasing factor overexpressionGENES, BRAIN AND BEHAVIOR, Issue 7 2007M. Kasahara Overproduction of corticotrophin-releasing factor (CRF), the major mediator of the stress response, has been linked to anxiety, depression and addiction. CRF excess results in increased arousal, anxiety and altered cognition in rodents. The ability to adapt to a potentially threatening stimulus is crucial for survival, and impaired adaptation may underlie stress-related psychiatric disorders. Therefore, we examined the effects of chronic transgenic neural CRF overproduction on behavioural adaptation to repeated exposure to a non-home cage environment. We report that CRF transgenic mice show impaired adaptation in locomotor response to the novel open field. In contrast to wild-type (WT) mice, anxiety-related behaviour of CRF transgenic mice does not change during repeated exposure to the same environment over the period of 7 days or at retest 1 week later. We found that locomotor response to novelty correlates significantly with total locomotor activity and activity in the centre at the last day of testing and at retest in WT but not in CRF transgenic mice. Mice were divided into low responders and high responders on the basis of their initial locomotor response to novelty. We found that differences in habituation and re-exposure response are related to individual differences in locomotor response to novelty. In summary, these results show that CRF transgenic mice are fundamentally different from WT in their ability to adapt to an environmental stressor. This may be related to individual differences in stress reactivity. These findings have implications for our understanding of the role of CRF overproduction in behavioural maladaptation and stress-related psychiatric disorders. [source] Single-trial analysis of oddball event-related potentials in simultaneous EEG-fMRIHUMAN BRAIN MAPPING, Issue 7 2007Christian-G. Abstract There has recently been a growing interest in the use of simultaneous electroencephalography (EEG) and functional MRI (fMRI) for evoked activity in cognitive paradigms, thereby obtaining functional datasets with both high spatial and temporal resolution. The simultaneous recording permits obtaining event-related potentials (ERPs) and MR images in the same environment, conditions of stimulation, and subject state; it also enables tracing the joint fluctuations of EEG and fMRI signals. The goal of this study was to investigate the possibility of tracking the trial-to-trial changes in event-related EEG activity, and of using this information as a parameter in fMRI analysis. We used an auditory oddball paradigm and obtained single-trial amplitude and latency features from the EEG acquired during fMRI scanning. The single-trial P300 latency presented significant correlation with parameters external to the EEG (target-to-target interval and reaction time). Moreover, we obtained significant fMRI activations for the modulation by P300 amplitude and latency, both at the single-subject and at the group level. Our results indicate that, in line with other studies, the EEG can bring a new dimension to the field of fMRI analysis by providing fine temporal information on the fluctuations in brain activity. Hum Brain Mapp, 2007. © 2007 Wiley-Liss, Inc. [source] A Comparative Study of the Use of Four Fall Risk Assessment Tools on Acute Medical WardsJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 6 2005Michael Vassallo FRCP Objectives: To compare the effectiveness of four falls risk assessment tools (STRATIFY, Downton, Tullamore, and Tinetti) by using them simultaneously in the same environment. Design: Prospective, open, observational study. Setting: Two acute medical wards admitting predominantly older patients. Participants: One hundred thirty-five patients, 86 female, mean age±standard deviation 83.8±8.01 (range 56,100). Measurements: A single clinician prospectively completed the four falls risk assessment tools. The extent of completion and time to complete each tool was recorded. Patients were followed until discharge, noting the occurrence of falls. The sensitivity, specificity, negative predictive accuracy, positive predictive accuracy, and total predictive accuracy were calculated. Results: The number of patients that the STRATIFY correctly identified (n=90) was significantly higher than the Downton (n=46; P<.001), Tullamore (n=66; P=.005), or Tinetti (n=52; P<.001) tools, but the STRATIFY had the poorest sensitivity (68.2%). The STRATIFY was also the only tool that could be fully completed in all patients (n=135), compared with the Downton (n=130; P=.06), Tullamore (n=130; P=.06), and Tinetti (n=17; P<.001). The time required to complete the STRATIFY tool (average 3.85 minutes) was significantly less than for the Downton (6.34 minutes; P<.001), Tinetti (7.4 minutes; P<.001), and Tullamore (6.25 minutes; P<.001). The Kaplan-Meier test showed that the STRATIFY (log rank P=.001) and Tullamore tools (log rank P<.001) were effective at predicting falls over the first week of admission. The Downton (log rank P=.46) and Tinetti tools (log rank P=.41) did not demonstrate this characteristic. Conclusion: Significant differences were identified in the performance and complexity between the four risk assessment tools studied. The STRATIFY tool was the shortest and easiest to complete and had the highest predictive value but the lowest sensitivity. [source] Contributions of genetic and environmental components to changes in phenotypic variation between generationsJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 4 2010A. Wolc Summary We evaluate the extent to which changes in phenotypic variation among generations of populations kept in the same environment are due to changes in genetic (VA) or in environmental (VE) variance. Data were available on body weight of adult poultry on a total of 89186 birds (mainly females) from six generations of each of seven lines of layers. There was substantial heterogeneity of variation between generations, shown to be in both VA and VE components. Based on the Akaike information criterion (AIC), the best fit was with both components changing, and a better fit was obtained if VA/VE (i.e. heritability) or VE, rather than VA, was assumed constant. In analyses of quantitative genetic data spanning environmental groups, attention should be paid to whether and how the variance components change among groups before undertaking detailed variance partition that may be sensitive to such changes. [source] Alternative community states maintained by fire in the Klamath Mountains, USAJOURNAL OF ECOLOGY, Issue 1 2010Dennis C. Odion Summary 1.,The earliest examples of alternative community states in the literature appear to be descriptions of natural vegetation said to both depend on and promote fire. Nonetheless, alternative community states determined by fire have rarely been documented at landscape scales and in natural vegetation. This is because spatial autocorrelation may confound analyses, experimental manipulations are difficult and a long-term perspective is needed to demonstrate that alternative community states can persist for multiple generations. 2.,We hypothesized that alternative community states occur in a largely forested landscape in the Klamath Mountains, north-western California, USA, where shrub-dominated sclerophyllous vegetation establishes after fire that is lethal to forests. Forests redevelop if succession is not arrested by fire. Our hypothesis would require that sclerophyll and forest vegetation states each be maintained by different self-reinforcing relationships with fire. 3.,To test this hypothesis, we examined pyrogenicity of forest and sclerophyll vegetation as a function of time since the previous fire, accounting for spatial autocorrelation. Fire exclusion served as a de facto experimental treatment. Areas where fire had proceeded to occur served as controls. 4.,Our findings are consistent with the occurrence of alternative community states established and maintained by different self-reinforcing feedbacks with fire. Sclerophyll vegetation was more pyrogenic, especially where time-since-fire (TSF) was relatively short, a favourable relationship for this fire-dependent vegetation. Forests were much less pyrogenic, especially where TSF was long, favouring their maintenance. Fire exclusion therefore has led to afforestation and rapid retreat of fire-dependent vegetation. 5.,Synthesis: We have documented how different self-reinforcing combustion properties of forest and sclerophyll vegetation can naturally produce alternative states coexisting side-by-side in the same environment. Such fire-mediated alternative states may be underappreciated, in part, because they are difficult to demonstrate definitively. In addition, the dynamics they exhibit contrast with common perceptions that fire hazard increases deterministically with TSF in forests and shrublands. Addressing the impacts of fire exclusion will probably require a management shift to better allow fire to perform its ecological role in shaping landscape diversity and maintaining fire-dependent biota. [source] Detection of Heterobasidion annosum s. l. [(Fr.) Bref.] in Norway Spruce by Polymerase Chain ReactionJOURNAL OF PHYTOPATHOLOGY, Issue 7 2002G. Bahnweg Abstract Internal transcribed spacer (ITS) sequences of the rDNA repeat unit of Heterobasidion annosum were used to design specific primers for the detection and quantification of this important forest pathogen by polymerase chain reaction (PCR). Specificity of detection was cross-checked against a variety of other fungi (saprophytes, root pathogens, mycorrhizal fungi) which may occur in the same environment. As little as 1 pg fungal DNA (equiv. to 10,40 genomes) could be detected in 200 ng spruce root DNA (from 1 mg fresh spruce root). The Heterobasidion -specific primers allowed simultaneous detection of Armillaria spp. in multiplex PCR. The method was successfully applied to increment cores of Norway spruce from the forest region Tharandter Wald (Saxonia, Germany), Oberbärenburg (East Ore Mountains, Saxonia) and Oberschleissheim (north of Munich, Bavaria). [source] Magnesium and sulphur in the calcite shells of two brachiopods, Terebratulina retusa and Novocrania anomalaLETHAIA, Issue 1 2007JENNIFER ENGLAND This study determines the distribution of magnesium and sulphur in the shells of two species of brachiopod from the same environment to highlight environmental and biological influences on shell composition. In Terebratulina retusa there are differences in magnesium concentration between the primary layer and the outer and inner regions of the secondary layer. In contrast, Novocrania anomala has a shell composed of high magnesium calcite and there is no significant difference in magnesium concentration between the primary and the secondary shell layers. Sulphur provides an indication of the distribution of sulphated organic matrix within the shells of T. retusa and N. anomala. In T. retusa the distribution of magnesium and sulphur correlates across the shell; however, there is no evidence for a relationship between magnesium and sulphur distribution in N. anomala. The relationship between magnesium and sulphur in T. retusa indicates that a proportion of the magnesium content of the shell is associated with the sulphated fraction of the organic matrix. In these two species of brachiopod, from the same environment, magnesium and organic concentration and distribution are very different, emphasizing the importance of fully understanding the factors that control biomineral composition before the application of these biominerals to environmental studies. [source] The host species affects the microbial community in the goat rumenLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2008P.J. Shi Abstract Aims:, This study was carried out to determine whether bacterial and ciliate populations in goat rumen vary significantly between different goat species living in the same environment. Methods and Results:, Bacterial and ciliate communities in the rumen of three goat species were analysed at the molecular level using denaturing gradient gel electrophoresis. The microbial community varied considerably among goats living in the same environment. Interspecies variation in the bacterial population was noticeably greater than intraspecies variation. In contrast, there was considerable variation in the ciliate population among goats within the same species, and intraspecies similarities were no greater than those observed across species. Conclusions:, Because environmental factors and diets were identical for all goats, differences in bacterial populations reflect species-specific differences in rumen microbes. Significance and Impact of the Study:, Factors related to the host species have an important effect on determining the bacterial composition in the goat rumen. [source] Feeding ecology of Xenoturbella bocki (phylum Xenoturbellida) revealed by genetic barcodingMOLECULAR ECOLOGY RESOURCES, Issue 1 2008SARAH J. BOURLAT Abstract The benthic marine worm Xenoturbella is frequently contaminated with molluscan DNA, which had earlier caused confusion resulting in a suggested bivalve relationship. In order to find the source of the contaminant, we have used molluscan sequences derived from Xenoturbella and compared them to barcodes obtained from several individuals of the nonmicroscopic molluscs sharing the same environment as Xenoturbella. Using cytochrome oxidase 1, we found the contaminating sequences to be 98% similar to the bivalve Ennucula tenuis. Using the highly variable D1,D2 region of the large ribosomal subunit in Xenoturbella, we found three distinct species of contaminating molluscs, one of which is 99% similar to the bivalve Abra nitida, one of the most abundant bivalves in the Gullmarsfjord where Xenoturbella was found, and another 99% similar to the bivalve Nucula sulcata. These data clearly show that Xenoturbella only contains molluscan DNA originating from bivalves living in the same environment, refuting former hypotheses of a bivalve relationship. In addition, these data suggest that Xenoturbella feeds specifically on bivalve prey from multiple species, possibly in the form of eggs and larvae. [source] A New Method to Test the Effectiveness of Sunscreen Ingredients in a Novel Nano-surface Skin Cell MimicPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2006Rajagopal Krishnan Photophysical properties of sunscreens are commonly studied in solvent media, which do not mimic the skin, or in complex artificial skin systems, which are difficult to handle. In an earlier study, we showed that polystyrene nanosphere suspensions mimic the mixed polarity environment of skin cell systems. This paper presents a new method to quantify the effectiveness of sunscreens in the polystyrene nanosphere environment. This method utilizes the intrinsic UV-B fluorescence of polystyrene nanospheres. We studied three UV-B sunscreens by this new method and compared their extinction coefficients with observed values in solvent. The values follow the trend observed in solvents, but the ratio of their extinction coefficient in solvent to the value obtained by this new method is 1.3,1.8 instead of 1. This difference might be caused by the mixed polarity or the microgeometry of the nanosphere system. Regardless of the difference in the extinction coefficients, this new system can be used to test hundreds of chemicals for their sunscreening potential in a cost-effective way. One marked advantage of this new method is its ability to test both hydrophobic and hydrophilic sunscreening chemicals in the same environment. This is virtually impossible for current solvent-based models, which require different solvents for hydrophobic and hydrophilic chemicals. The new method also allows the simultaneous evaluation of a host of photophysical properties of sunscreening chemicals. [source] Aphid parasitoids detect that an alien plant was present nearby during their developmentPHYSIOLOGICAL ENTOMOLOGY, Issue 3 2002H. F. Van Emden Abstract Glasshouse and laboratory experiments were conducted with Aphidius rhopalosiphi parasitizing Metopolophium dirhodum to test whether the presence in the same environment of another plant species (tomato or marigold) induced aerial allelopathy in wheat plants. Emerging parasitoids were offered the choice of two odours of wheat plants in an olfactometer , wheat grown alone and wheat grown in the presence of the second plant species. Female parasitoids responded more strongly than males, but both sexes preferred the odour of wheat grown in the environment in which they had developed (i.e. with or without the second plant species present). Moving the tomato plants from the cages where they had been placed with wheat to the cages that had previously had wheat alone just before the aphid mummy formed showed that the odour environment the emerging parasitoid responded to was that of the mummy rather than that of the developing parasitoid larva. From this it was concluded that the parasitoids in the olfactometer were responding not only to wheat volatiles, but also to tomato volatiles absorbed on the surface of the mummy and encountered by the emerging adult parasitoid. By excising the parasitoid pupa from the mummy formed on one wheat cultivar, and offering the emerging parasitoids the surface of aphid mummies formed on a different cultivar, it was confirmed that olfactometer responses represented a learning of the chemistry of the surface of the mummy encountered at or after emergence. [source] Linking microbial oxidation of arsenic with detection and phylogenetic analysis of arsenite oxidase genes in diverse geothermal environmentsENVIRONMENTAL MICROBIOLOGY, Issue 2 2009N. Hamamura Summary The identification and characterization of genes involved in the microbial oxidation of arsenite will contribute to our understanding of factors controlling As cycling in natural systems. Towards this goal, we recently characterized the widespread occurrence of aerobic arsenite oxidase genes (aroA -like) from pure-culture bacterial isolates, soils, sediments and geothermal mats, but were unable to detect these genes in all geothermal systems where we have observed microbial arsenite oxidation. Consequently, the objectives of the current study were to measure arsenite-oxidation rates in geochemically diverse thermal habitats in Yellowstone National Park (YNP) ranging in pH from 2.6 to 8, and to identify corresponding 16S rRNA and aroA genotypes associated with these arsenite-oxidizing environments. Geochemical analyses, including measurement of arsenite-oxidation rates within geothermal outflow channels, were combined with 16S rRNA gene and aroA functional gene analysis using newly designed primers to capture previously undescribed aroA -like arsenite oxidase gene diversity. The majority of bacterial 16S rRNA gene sequences found in acidic (pH 2.6,3.6) Fe-oxyhydroxide microbial mats were closely related to Hydrogenobaculum spp. (members of the bacterial order Aquificales), while the predominant sequences from near-neutral (pH 6.2,8) springs were affiliated with other Aquificales including Sulfurihydrogenibium spp., Thermocrinis spp. and Hydrogenobacter spp., as well as members of the Deinococci, Thermodesulfobacteria and ,- Proteobacteria. Modified primers designed around previously characterized and newly identified aroA -like genes successfully amplified new lineages of aroA- like genes associated with members of the Aquificales across all geothermal systems examined. The expression of Aquificales aroA- like genes was also confirmed in situ, and the resultant cDNA sequences were consistent with aroA genotypes identified in the same environments. The aroA sequences identified in the current study expand the phylogenetic distribution of known Mo-pterin arsenite oxidase genes, and suggest the importance of three prominent genera of the order Aquificales in arsenite oxidation across geochemically distinct geothermal habitats ranging in pH from 2.6 to 8. [source] | |||||||||||||