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131.
Remote sensing of phytoplankton-macrophyte coexistence in shallow hypereutrophic fluvial lakes 总被引:1,自引:0,他引:1
Rossano Bolpagni Mariano Bresciani Alex Laini Monica Pinardi Erica Matta Eva M. Ampe Claudia Giardino Pierluigi Viaroli Marco Bartoli 《Hydrobiologia》2014,737(1):67-76
We investigated with remote sensing (APEX images) the coexistence of phytoplankton and macrophytes in three interconnected shallow and hypereutrophic fluvial lakes (Mantua Lakes, Northern Italy). High concentrations of chlorophyll-a, up to 60 mg m?3, were determined in the open water between well-developed stands of floating-leaved, submerged, and emergent macrophytes. Our data suggest a general inhibition of phytoplankton by macrophytes, evidenced by decreasing chlorophyll-a concentrations in proximity of macrophyte stands. Chlorophyll-a concentrations halved in the proximity of emergent stands (~6 mg m?3 within 21 m from the stand border) when compared to the outer zones (~13 mg m?3). Contrasting trends were observed for submerged stands, where concentrations decreased inwards from ~8 to ~3 mg m?3. Floating leaved stands had a neutral effect, chlorophyll-a being nearly constant in both inner and outer zones. Overall, remotely-sensed data allow evaluation of quantitative and spatially defined interactions of macrophytes and phytoplankton at the whole ecosystem scale. 相似文献
132.
Voyles J Richards-Hrdlicka K Cashins SD Rosenblum EB Hyatt AD Berger L Skerratt LF 《Diseases of aquatic organisms》2010,92(2-3):109-112
The fungal pathogen Batrachochytrium dendrobatidis (Bd) causes the disease chytridiomycosis, which is lethal to many species of amphibians worldwide. Many studies have investigated the epidemiology of chytridiomycosis in amphibian populations, but few have considered possible host-pathogen coevolution. More specifically, investigations focused on the evolution of Bd, and the link with Bd virulence, are needed. Such studies, which may be important for conservation management of amphibians, depend on access to Bd isolates. Here we provide a summary of known Bd isolates that have been collected and archived in various locations around the world. Of 257 Bd isolates, we found that 53% originate from ranids in the United States. In many cases, detailed information on isolate origin is unavailable, and it is unknown how many isolates are cryo-archived. We suggest the creation of a centralized database of isolate information, and we urge researchers and managers to isolate and archive Bd to facilitate future research on chytridiomycosis. 相似文献
133.
Erik Vollbrecht Jon Duvick Justin P. Schares Kevin R. Ahern Prasit Deewatthanawong Ling Xu Liza J. Conrad Kazuhiro Kikuchi Tammy A. Kubinec Bradford D. Hall Rebecca Weeks Erica Unger-Wallace Michael Muszynski Volker P. Brendel Thomas P. Brutnell 《The Plant cell》2010,22(6):1667-1685
The maize (Zea mays) transposable element Dissociation (Ds) was mobilized for large-scale genome mutagenesis and to study its endogenous biology. Starting from a single donor locus on chromosome 10, over 1500 elements were distributed throughout the genome and positioned on the maize physical map. Genetic strategies to enrich for both local and unlinked insertions were used to distribute Ds insertions. Global, regional, and local insertion site trends were examined. We show that Ds transposed to both linked and unlinked sites and displayed a nonuniform distribution on the genetic map around the donor r1-sc:m3 locus. Comparison of Ds and Mutator insertions reveals distinct target preferences, which provide functional complementarity of the two elements for gene tagging in maize. In particular, Ds displays a stronger preference for insertions within exons and introns, whereas Mutator insertions are more enriched in promoters and 5′-untranslated regions. Ds has no strong target site consensus sequence, but we identified properties of the DNA molecule inherent to its local structure that may influence Ds target site selection. We discuss the utility of Ds for forward and reverse genetics in maize and provide evidence that genes within a 2- to 3-centimorgan region flanking Ds insertions will serve as optimal targets for regional mutagenesis. 相似文献
134.
Anderson O. Lobo Erica F. Antunes Mariana BS Palma Cristina Pacheco‐Soares Vladimir J. Trava‐Airoldi Evaldo J. Corat 《Cell biology international》2010,34(4):393-398
Monolayer formation of SaOS‐2 (human osteoblast‐like cells) was observed on VACNT (vertically aligned multiwalled carbon nanotubes) scaffolds without purification or functionalization. The VACNT were produced by a microwave plasma chemical vapour deposition on titanium surfaces with nickel or iron as catalyst. Cell viability and morphology studies were evaluated by LDH (lactate dehydrogenase) release assay and SEM (scanning electron microscopy), respectively. The non‐toxicity and the flat spreading with monolayer formation of the SaOs‐2 on VACNT scaffolds surface indicate that they can be used for biomedical applications. 相似文献
135.
Sabah O. Odman-Ghazi Abraham Abraha Erica Taylor Isom Margaret M. Whalen 《Cell biology and toxicology》2010,26(5):469-479
Previous studies have shown that dibutyltin (DBT) interferes with the function of human natural killer (NK) cells, diminishing
their capacity to destroy tumor cells, in vitro. DBT is a widespread environmental contaminant and has been found in human
blood. As NK cells are our primary immune defense against tumor cells, it is important to understand the mechanism by which
DBT interferes with their function. The current study examines the effects of DBT exposures on key enzymes in the signaling
pathway that regulates NK responsiveness to tumor cells. These include several protein tyrosine kinases (PTKs), mitogen-activated
protein kinases (MAPKs), and mitogen-activated protein kinase kinases (MAP2Ks). The results showed that in vitro exposures
of NK cells to DBT had no effect on PTKs. However, exposures to DBT for as little as 10 min were able to increase the phosphorylation
(activation) of the MAPKs. The DBT-induced activations of these MAPKs appear to be due to DBT-induced activations of the immediate
upstream activators of the MAPKs, MAP2Ks. The results suggest that DBT-interference with the MAPK signaling pathway is a consequence
of DBT exposures, which could account for DBT-induced decreases in NK function. 相似文献
136.
Douglas?C.?TozerEmail author Erica?Nol Kenneth?F.?Abraham 《Wetlands Ecology and Management》2010,18(6):679-693
Both local and landscape-scale habitat variables influence the abundance of wetland breeding birds. Few studies, however,
simultaneously assess the effects of habitat variables at multiple spatial scales or consider effects on reproductive success.
Therefore, we examined the effects of wetland and landscape-scale habitat variables on the abundance of nine breeding bird
species and the effects of nest, wetland, or landscape-scale habitat variables on the nest success, clutch size, or number
of fledglings of four species at 15 cattail (Typha sp.)-dominated wetlands in an agricultural region around Peterborough, Ontario, Canada. The abundance of Least Bittern (Ixobrychus exilis), Common Moorhen (Gallinula chloropus), and Marsh Wren (Cistothorus palustris) increased as wetland water depth increased; the abundance of Common Moorhen and Marsh Wren increased as wetland size increased;
and the abundance of Marsh Wren increased as the amount of wetland in the surrounding landscape increased. Red-winged Blackbird
(Agelaius phoeniceus) nest success decreased as nest cover increased. Clutch sizes were uninfluenced by the habitat variables that we considered.
The number of Red-winged Blackbird fledglings per successful nest increased as wetland size increased and as the amount of
wetland in the surrounding landscape increased. We speculate that food limitation in small wetlands may be responsible for
the pattern in Red-winged Blackbird fledging success. The abundance and nest success of Virginia Rail (Rallus limicola) and Sora (Porzana carolina) were uninfluenced by the habitat variables we considered. Future research should consider mate attraction and productivity
in relation to local and landscape-scale habitat variables for these and other secretive species. Our study suggests that
wetland conservation will be most effective if it considers habitat variables at multiple spatial scales. 相似文献
137.
Explorative wood anatomical analysis was conducted on a Castanea sativa stand in southern Switzerland, where a moderate-intensity surface fire burned in April 1997. Cross-sections were sampled
at multiple heights from 20 scarred shoots, 20 apparently intact shoots, along with cores taken from 20 reference trees outside
the fire area. Thin sections were prepared from uphill and downhill locations on the circumference for up to 5 years preceding
and following the event year. The thin sections were visually observed in order to identify a response to the known fire event
preserved in the wood anatomical structure. Anatomical features were observed at the uphill and downhill locations on both
scarred and intact (unscarred) cross-sections, and they occurred in a subset of the observed samples. The features observed
in both scarred and intact cross-sections were an apparent increase in vessel density and a decrease in lumen area of the
second row of earlywood vessels, along with tyloses formation in the first row of earlywood vessels. Furthermore, the scarred
region exhibited a zone of delayed cambial death following the fire, and the onset of woundwood was often initiated later
in the season or the following year. Using the type of features and their location around the circumference, we inferred that
the observed features may have formed in response to local heating of the cambium, and likely formed in response to canopy
damage. 相似文献
138.
139.
Wehrwein EA 《Journal of applied physiology (Bethesda, Md. : 1985)》2010,109(6):2009
140.
Margaret E. Brosnan Erica E. Edison Robin da Silva John T. Brosnan 《Advances in enzyme regulation》2007,47(1):252-260
The text-book view of the role of the creatine/creatine phosphate system as an energy buffer has been expanded to include functions such as energy shuttling, proton buffering and regulating cytosolic ADP levels. There is continuous need for creatine replacement due to creatinine formation. Replacement involves a combination of diet and de novo synthesis. Creatine synthesis makes very significant demands on amino acid metabolism, in particular that of glycine, arginine and methionine. It uses about 40% of all methyl groups transferred from S-adenosylmethionine. Although the traditional view of the function of the creatine/creatine phosphate system is largely concerned with its role in skeletal and cardiac muscle, recent work obliges us to take a broader view. In particular, its role in the brain is brought into sharp focus by the neurological symptoms displayed by children suffering from inborn errors of creatine synthesis and transport, as well as by suggestions that brain creatine status may play a role in cognitive performance in adults. 相似文献