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Pilot Experiment (pilot + experiment)
Selected AbstractsEvaluation of Transgenic Poplars Over-Expressing Enzymes of Glutathione Synthesis for Phytoremediation of CadmiumPLANT BIOLOGY, Issue 6 2002A. Koprivova Abstract: Recently, phytoremediation of soils polluted with heavy metals has received a lot of attention. Since glutathione (GSH) and its derivatives (e.g., phytochelatins) play a major role in plant defence against environmental pollutants, we tested the effects of over-expression of bacterial genes for GSH synthesis in poplar on cadmium accumulation. A pilot experiment with CdCl2 in hydroponics revealed that poplars over-expressing ,-glutamylcysteine synthetase (,-ECS) accumulated significantly more Cd in root tissue than wild type or glutathione synthetase over-expressing poplars. To test the partitioning of Cd in different organs, poplar lines over-expressing ,-ECS in the cytosol and in chloroplasts were treated with 0.2 mM CdCl2 in hydroponics. Significant amounts of Cd were translocated to leaves, but significant differences in Cd accumulation were not observed between transgenic and wild type plants. To evaluate these lines for large-scale phytoremediation of cadmium, plants were treated with 2 mM Cd in soil. Over a four-week period, the poplar plants were able to accumulate up to 5.3 mg Cd. Most remarkably, in young leaves of both transgenic lines, Cd was accumulated to concentrations 2.5 - 3 times higher than in the wild type. The increased allocation of cadmium to the young leaves represents a potentional advantage for the phytoremediation process using the same plants over several vegetation periods. The use of transgenic poplar lines with enhanced glutathione production capacity seems to be of particular advantage in highly polluted soils. [source] Effect of Grazing on Restoration of Endemic Dwarf Pine (Pinus culminicola Andresen et Beaman) Populations in Northeastern MexicoRESTORATION ECOLOGY, Issue 1 2005J Jiménez Abstract A pilot experiment designed to test the effect of cattle, small mammals, and elevation on the success of reforestation of an endemic dwarf pine species in northeastern Mexico was implemented. Pinus culminicola (Andresen et Beaman) grows only in four high peaks in the Sierra Madre Oriental and is under pressure from grazing, wildfires, and human activities such as mining, road development for timber extraction, and telecommunication and aerial navigation devices. We planted and monitored 2-year-old seedlings at three elevations within the natural distribution range of this species at Cerro El Potosí in Nuevo León, Mexico. At each elevation three treatments were established: (1) seedlings protected from cattle plus small mammals, (2) seedlings protected from cattle, and (3) seedlings with free access to cattle and small mammals. Seedling survival was approximately 50% in (1) after 4 years, but there were no surviving seedlings with free access to cattle. Elevation in general did not account for variation in survival. Seedling growth was poor during the 4 years, which implies that seedlings remain susceptible to grazing and trampling by cattle and small mammals. The implications for a large-scale restoration program are discussed. [source] Sensorimotor memory and grip force control: does grip force anticipate a self-produced weight change when drinking with a straw from a cup?EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2003Dennis A. Nowak Abstract We examined whether self-generated weight changes are anticipated by adequate grip force adjustments when repeatedly lifting an instrumented manipulandum. Subjects lifted a cup filled with 500 mL of water prior to and following drinking two portions of water with a straw without touching it. One half of the subjects drank from and lifted an uncovered cup receiving constant visual information about its filling level and the other half of the subjects drank from a covered cup without such visual feedback. During the lifts immediately following the drinking procedures, grip force scaling was erroneously programmed for the heavier weight of the preceding lift as was obvious from an inadequately high rate of grip force development. Vision had only a minor influence on the rate of grip force increase. The influence of vision on the scaling of peak grip force was more pronounced. More accurate force scaling was obtained with an increasing number of lifts performed under each weight condition, indicating an ongoing force adjustment process probably based on sensory feedback. We conclude that self-generation of a change in the weight of an object to be lifted is not, in itself, sufficient to elicit a predictive grip force output. Rather, accurate feedback information associated with the self-generated weight change is essential to update internal models related to the mechanical object properties. This assumption was confirmed in pilot experiments; when subjects lifted the cup after having poured water from it, they accurately scaled their fingertip force to the self-produced weight change. Here, direct sensory feedback from the grasping fingers could signal the weight change and update internal models while pouring water from the cup. Our data support the hypothesis that the sensorimotor system planning and processing predictive fingertip force can operate independently of higher-level cognitive and perceptual systems. [source] Responsible estuarine finfish stock enhancement: an Australian perspectiveJOURNAL OF FISH BIOLOGY, Issue 2 2005M. D. Taylor The responsible approach to marine stock enhancement is a set of principles aimed at maximising the success and benefits of artificially re-stocking depleted fisheries. The benefits of such an approach are evident in the 400% increase in survival of stocked striped mullet in Hawaii through refinement of release techniques, however financially or temporally constrained stocking programs in Australia have not adhered to all principles. A pragmatic approach to address these principles is proposed, using international examples and Australian marine finfish pilot stockings of barramundi, mulloway, sand whiting, dusky flathead and black bream. Biological ranking of candidate species by estuarine residency, a low natural-mortality to growth ratio, a large L, and comparison by recreational value and available rearing technologies, show that mulloway, barramundi and sea mullet are ideal species for stocking in Australia. Australian intermittently closed opening landlocked lagoons and recreational fishing havens, especially near cities, provide experimental opportunities to apply this approach and stock suitable species through small-scale pilot experiments. This would allow evaluation of production and carrying capacity, and density dependent processes with respect to optimal stocking strategies unconfounded by emigration and commercial fishing practices. Twenty per cent of Australians fish each year, and harvest approximately 27 000 t of finfish. Stocking recreationally important species in Australia should give a greater financial benefit, which is spread across a larger cross-section of the community, compared to stocking to enhance commercial fisheries. The pragmatic application of the responsible approach, and stocking of fast growing estuarine residents into recreational fishing havens would enhance the benefit from marine stocking. [source] | ||||||||||