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Diverse Responses (diverse + response)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

Effect of laser cleaning on granite color

COLOR RESEARCH & APPLICATION, Issue 2 2007
Carlota M. Grossi
Abstract This article presents the effect of laser radiation on the color of ornamental granites used for external cladding. The laboratory experimentation was undertaken on a widely used coarse-grain granite commercially known as Rosa Porriño. The irradiation was carried out with a Q-switched Nd:YAG laser at 1064 nm and several energy densities (fluences) on polished surfaces, dry and wet, uncoated, and artificially coated-simulating a black crust. Laser effects on the granite surface were determined by color measurements with a colorimeter. These measurements made possible to determine probable damage due to laser radiation and the diverse response of different minerals. The analysis of the data also suggests potential causes for the color change and applicability limits of the technique. The a*-parameter, or red,green component, is the most affected, leading to a change in hab (hue) and was interpreted as a result in variations in the Fe compounds, which strongly condition stone color. No significant changes in L* (luminosity or lightness) or Cab* (chroma) may indicate no relevant alterations in the surface polish. When using laser irradiation to remove black layers on granite surfaces, variations of L* can be indicative of the cleaning effectiveness. This research results may be useful to select laser parameters when managing ornamental granite cleaning operations. However, they also suggest the need of further experimentation in specific techniques of analysis as well as different laser wavelengths. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 152 , 159, 2007 [source]

A field-based microcosm method to assess the effects of polluted urban stream sediments on aquatic macroinvertebrates

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2005
Vincent Pettigrove
Abstract A method using field-based microcosms was developed to determine the effects of contaminated sediments on aquatic macroinvertebrates. Fine sediments from nonpolluted, moderately polluted, and severely polluted bodies of water were placed in microcosms positioned within the littoral zone of a nonpolluted wetland near Melbourne (Victoria, Australia). In three experiments, 47 taxa, including 18 Chironomidae, 6 taxa from other Diptera families, and 7 Hemiptera taxa, colonized the microcosms, mostly via eggs deposited by flying adults. The effects of sediment type on the presence and abundance of common taxa were considered statistically. Pollution levels in sediments (indexed either by a principal components analysis or by the concentration of zinc, the predominant metal) resulted in reduced occurrence and abundance of eight taxa but had no effect on another five taxa. These findings were validated with an extensive field database for the distribution of macroinvertebrates and associated concentrations of zinc in sediments from streams and wetlands in the Melbourne region. The occurrence of eight taxa and the abundance of two taxa varied at similar zinc concentrations in sediments from both the microcosms and the field. Patterns for another two species did not match the microcosm results, but these groups contained multiple species with potentially diverse responses. The present results suggest that contaminant levels in sediments probably have a direct effect on the occurrence and abundance of macroinvertebrates in bodies of water in urban areas. The microcosm method can be used to gather information regarding the effects of sediment quality on macroinvertebrates in lentic habitats, particularly for indigenous species that cannot be easily reared or tested in laboratory conditions. Because almost all macroinvertebrates in microcosms develop from eggs, the most sensitive life stages (i.e., first and second instars) are exposed to polluted sediments. [source]

Molecular cloning and expression regulation of PRG-3, a new member of the plasticity-related gene family

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2004
Nicolai E. Savaskan
Abstract Phospholipid-mediated signalling on neurons provokes diverse responses such as neurogenesis, pattern formation and neurite remodelling. We have recently uncovered a novel set of molecules in the mammalian brain, named plasticity-related genes (PRGs), which mediate lipid phosphate phosphatase activity and provide evidence for their involvement in mechanisms of neuronal plasticity. Here, we report on a new member of the vertebrate-specific PRG family, which we have named plasticity-related gene-3 (PRG-3). PRG-3 is heavily expressed in the brain and shows a specific expression pattern during brain development where PRG-3 expression is found predominantly in neuronal cell layers and is already expressed at embryonic day 16. In the mature brain, strongest PRG-3 expression occurs in the hippocampus and cerebellum. Overexcitation of neurons induced by kainic acid leads to a transient down-regulation of PRG-3. Furthermore, PRG-3 is expressed on neurite extensions and promotes neurite growth and a spreading-like cell body in neuronal cells and COS-7 cells. In contrast to previously described members of the PRG family, PRG-3 does not perform its function through enzymatic phospholipid degradation. In summary, our findings feature a new member of the PRG family which shows dynamic expression regulation during brain development and neuronal excitation. [source]

Chaperone and anti-chaperone: Two-faced synuclein as stimulator of synaptic evolution

NEUROPATHOLOGY, Issue 5 2006
Masayo Fujita
Previous studies have shown that ,-synuclein (,-syn), the homologue of ,-syn, inhibited ,-syn aggregation and stabilized Akt cell survival signaling molecule, suggesting that ,-syn was protective against ,-syn-related neurodegenerative disorders, such as Parkinson's disease and diffuse Lewy body disease. However, emerging evidence argues that the situation may be not so simple. Two missense mutations of ,-syn were identified in familial and sporadic diffuse Lewy body disease, and wild type ,-syn was induced to form fibril structures in vitro, while, ,-syn was shown to be protective against neurodegeneration caused by deletion of cysteine-string protein-,, the presynaptic cochaperone to Hsc70 in mice. Collectively, ,- and ,-syn are both, but in varying degrees, featured with two opposite properties, namely normal chaperone and anti-chaperone. By reviewing recent progress in syn biology with a particular focus on ,-syn, this manuscript refers to the intriguing possibility that the dual syn proteins might have acquired a driving force for synaptic evolution. Hypothetically, the anti-chaperone syn may provoke stress-induced diverse responses, whereas, the chaperone syn may provide buffering for them, allowing accumulation of nonlethal phenotypic variations in synapses. Consequently, dual syn proteins may cope with forth-coming stresses in the brain by stimulating adaptive evolution. In this context, failure to regulate this process due to various causes, such as gene mutations and environmental risk factors, may result in imperfect adaptability against stresses, leading to neurodegenerative disorders. [source]