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1.
Senescent, naturally dried leaves of Typha domingensis were incubated inthe littoral region of a coastal lagoon and epiphytic bacterial volume,abundance, biomass and secondary productivity were measured during 127 daysof decomposition. The peak of cell abundance was registered at t =127 days when expressed per leaf surface area (10.07×107cells cm-2; 7.26 µgC cm-2), and at t= 26 days when expressed per biofilm dry mass (38.10 ×107 cells (mgDM biofilm)-1, 30.52 µgC(mgDM biofilm)-1). The highest values of bacterial biovolumesand lower turnover time were usually obtained in the beginning of thecolonization. Leu:Tdr ratios were also higher in the beginning of thecolonization, when bacterial community presented unbalanced metabolism.Consequently, the highest discrepancies between the bacterial secondaryproduction estimated by leu and Tdr incorporation were observed in the first2 days of decomposition. On average, the bacterial secondary productivityestimated by leu incorporation was 2.1 times higher than the valuesestimated by Tdr incorporation when the empirical factor for Tdr wasobtained from the relationship between Tdr and biomass increment. Thisdifference increased to 4.2 when the empirical factor was obtained from therelationship between Tdr and cell numbers increment. An average of bothmethods (0.0037 to 0.1397 µgC cm-2 h-1)produced results that fall within the range reported in the literature forepiphytic bacteria of freshwater ecosystems. 相似文献
2.
WILLIAM A. ROTTSCHAEFER 《Biology & philosophy》1997,12(3):369-384
In his recent The Temptation of Evolutionary Ethics, Paul Farber has given a negative assessment of the last one hundred years of attempts in Anglo-American philosophy, beginning with Darwin, to develop an evolutionary ethics. Farber identifies some version of the naturalistic fallacy as one of the central sources for the failures of evolutionary ethics. For this reason, and others, Farber urges that though it has its attraction, evolutionary ethics is a temptation to be resisted. In this discussion I identify three major, historically relevant forms of the naturalistic fallacy, the (1) the deductive, (2) genetic, and (3) open question forms and argue that none of them pose an intrinsic problem for evolutionary ethics. I conclude that on this score at least there is no reason to resist temptation. 相似文献
3.
《植物生态学报》2013,22(3):277
A scientific workflow system is designed specifically to organize, manage and execute a series of research steps, or a workflow, in a given runtime environment. The vision for scientific workflow systems is that the scientists around the world can collaborate on designing global-scaled experiments, sharing the data sets, experimental processes, and results on an easy-to-use platform. Each scientist can create and execute their own workflows and view results in real-time, and then subsequently share and reuse workflows among other scientists. Two case studies, using the Kepler system and BioVeL, are introduced in this paper. Ecological niche modeling process, which is a specialized form of scientific workflow system included in both Kepler system and BioVeL, was used to describe and discuss the features, developmental trends, and problems of scientific workflows. 相似文献
4.
Ozone (O3) is damaging to plants, inducing signalling pathways involving antagonism between jasmonates and ethylene. These pathways mediate O3 responses, particularly to acute exposure, and their manipulation protected several species against acute and chronic O3. We use chronic daily exposure of up to 163 ppb O3, and twice weekly application of up to 320 µg plant?1 methyl jasmonate (MeJA) to test two hypothesizes: 1) a low rate of MeJA does not affect growth but increases O3 sensitivity; 2) a high rate inhibits growth but reduces O3 sensitivity. Both hypotheses were rejected. Growth declined with increases in both MeJA and O3. MeJA at 40 µg plant?1 caused no direct effect, and at 160 µg plant?1 reduced growth similarly at all O3. Neither rate altered O3 sensitivity. These additive responses are not consistent with protection by MeJA in this system. They may reflect inter‐specific differences in signalling, since O3 concentrations used here exceeded some reported acute exposures. Alternatively, parallel responses to O3 and MeJA may suggest that O3‐induced jasmonates play a developmental role in chronic response but no protective role in the absence of lesions characteristic of acute exposure. MeJA appears useful as a probe of these mechanisms. 相似文献
5.
Katharina Bork Johannes Karstensen Martin Visbeck Andreas Zimmermann 《Ocean Development & International Law》2013,44(3):298-328
This article analyzes the legal status of unmanned instruments (particularly, floats and gliders) for observation purposes in the ocean environment. These new kinds of instruments are being deployed by the thousands into the oceans, not the least as part of the Argo Project of the International Oceanographic Commission. Their uncontrolled drifting has raised legal questions, especially when such instruments enter waters subject to the jurisdiction of foreign states. The authors argue that the current international legal framework is insufficient to address the pertinent issues, and that a new legal regime is needed. 相似文献
6.
Douglas Sipp 《Journal of cellular biochemistry》2009,107(5):853-856
Stem cell research stands as a high‐priority field in many countries across the Asia‐Pacific region, and the past decade has seen remarkable investment into facilities and programs intended to increase competitiveness in the drive to find clinical applications. In the years roughly framed by Korean cloner Woo‐Suk Hwang's meteoric ascent and fall, speculation was rampant that Asia was poised to overtake the West in this field of science. But that potential remains unfulfilled. In this article, I will look at some of the deficits in infrastructure and governance that underlie the East–West stem cell gap, and suggest a number of measures that might be taken to remedy them. J. Cell. Biochem. 107: 853–856, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
7.
Thomas Bell Michael B. Bonsall Angus Buckling Andrew S. Whiteley Timothy Goodall Robert I. Griffiths 《Biology letters》2010,6(5):639-642
Productivity and predation are thought to be crucial drivers of bacterial diversity. We tested how the productivity–diversity of a natural bacterial community is modified by the presence of protist predators with different feeding preferences. In the absence of predators, there was a unimodal relationship between bacterial diversity and productivity. We found that three protist species (Bodo, Spumella and Cyclidium) had widely divergent effects on bacterial diversity across the productivity gradient. Bodo and Cyclidium had little effect on the shape of the productivity–diversity gradient, while Spumella flattened the relationship. We explain these results in terms of the feeding preferences of these predators. 相似文献
8.
The economic viability of the wildlife based enterprises (bee-keeping and caterpillar utilization) in Malawi is discussed in relation to conventional agricultural enterprises (maize, beans and ground-nuts). A strong incentive emerges for rural people to adopt wildlife management as an adjunct to subsistence agriculture, and therefore, to promote conservation of natural ecosystems and wildlife habitats in the face of growing human population and demand for land. Dependence on agriculture has depleted the wildlife resource outside protected areas and has been less effective in improving the wealth and living standards of most rural people. This study illustrates that the Malawi Department of National Parks and Wildlife needs to introduce economic incentives that integrate biological conservation with economic development for the rural people. The management programme involves the adoption of a rotation burning policy that promotes vegetation coppicing, eases harvesting and promotes high caterpillar yields. 相似文献
9.
Edward Paul 《Cell biochemistry and biophysics》1987,11(1):57-63
A model of primary productivity in a salt marsh is developed and compared to a regression analysis study of data showing dependence
of growth on growing season, mean tidal height, and average monthly temperatures for several grass species. 相似文献
10.