Kinetics of hydrolysis and cyclization of ethyl 2-(aminosulfonyl)benzoate to saccharin

The cyclization of ethyl 2-(aminosulfonyl)benzoate (ASB) to give saccharin was investigated in aqueous solutions at pH between 5.2 and 9.5 and in the temperature range of 296.2-334.2 K. The initial concentration of the reactant was varied between 1.45 x 10(-5) and 3.86 x 10(-4) M. Ultraviolet spectroscopy was used to obtain the kinetic data. The reaction is acid catalyzed and follows pseudo-first-order kinetics. The experimental rate constant, k(obs), increases with temperature and pH. Its dependence on the temperature and pH is well described by: k(obs) = k1 [OH-] = [(2.52 +/- 0.9) x 10(16) exp(-20.2 +/- 1 kcalmol(-1)/RT) s(-1)][OH-] A mechanism is proposed and the half-life of ethyl ASB is calculated.     

Ameliorating effects of industrial sugar residue on the Jales gold mine spoil (NE Portugal) using Holcus lanatus and Phaseolus vulgaris as indicators

Phytostabilisation of bare heavily contaminated substrate, such as abandoned mine sites, is considered a very appropriate technology in order to diminish erosion and dispersion of contaminants into the surroundings. In this short-term pot study, application of industrial sugar residue (ISR), a waste product of the sugar industry, proved to ameliorate spoils conditions for plant performance by elevating pH and immobilising several metals. Although arsenate concentrations were positively correlated to spoil pH and spoil treatment with ISR mobilised As, growth of both Phaseolus vulgaris and Holcus lanatus improved significantly after applications of 3.75 g ISR kg(-1) dry spoil. Nutrient uptake from the substrate, with the exception of potassium, was elevated by ISR. As a remediation technique ISR application could be effective although in As-contaminated sites application might be restricted to areas where leaching to (ground) water does not form a risk.     

<Emphasis Type="Italic">Symbiodinium</Emphasis> sp. associations in the gorgonian<Emphasis Type="Italic"> Pseudopterogorgia elisabethae</Emphasis> in the Bahamas: high levels of genetic variability and population structure in symbiotic dinoflagellates

Little is known concerning the fine-scale diversity, population structure, and biogeography for Symbiodinium spp. populations inhabiting particular invertebrate species, including the gorgonian corals, which are prevalent members of reef communities in the Gulf of Mexico, the Caribbean, and the western Atlantic. This study examined the Symbiodinium sp. clade B symbionts hosted by the Caribbean gorgonian Pseudopterogorgia elisabethae (Bayer). A total of 575 colonies of P. elisabethae were sampled in 1995 and 1998–2000 from 12 populations lying along an ~450 km transect in the Bahamas and their Symbiodinium sp. clade B symbionts genotyped at two polymorphic dinucleotide microsatellite loci. Twenty-three unique, two-locus genotypes were identified in association with these P. elisabethae colonies. Most colonies hosted only a single Symbiodinium sp. clade B genotype; however, in some instances ( n=25), two genotypes were harbored simultaneously. For 10 of the 12 populations, 66–100% of the P. elisabethae colonies hosted the same symbiont genotype. Added to this, in 9 of the 12 populations, a Symbiodinium sp. clade B genotype was either unique to a population or found infrequently in other populations. This distribution of Symbiodinium sp. clade B genotypes resulted in statistically significant ( P<0.05 or <0.001) differentiation in 62 of 66 pairwise comparisons of P. elisabethae populations. Tests of linkage disequilibrium suggested that a combination of clonal propagation of the haploid phase and recombination is responsible for maintaining these distinct Symbiodinium sp. clade B populations.     

RNAi-mediated silencing of vitellogenin gene function turns honeybee (Apis mellifera) workers into extremely precocious foragers

The switch from within-hive activities to foraging behavior is a major transition in the life cycle of a honeybee (Apis mellifera) worker. A prominent regulatory role in this switch has long been attributed to juvenile hormone (JH), but recent evidence also points to the yolk precursor protein vitellogenin as a major player in behavioral development. In the present study, we injected vitellogenin double-stranded RNA (dsVg) into newly emerged worker bees of Africanized genetic origin and introduced them together with controls into observation hives to record flight behavior. RNA interference-mediated silencing of vitellogenin gene function shifted the onset of long-duration flights (>10 min) to earlier in life (by 3–4 days) when compared with sham and untreated control bees. In fact, dsVg bees were observed conducting such flights extremely precociously, when only 3 days old. Short-duration flights (<10 min), which bees usually perform for orientation and cleaning, were not affected. Additionally, we found that the JH titer in dsVg bees collected after 7 days was not significantly different from the controls. The finding that depletion of the vitellogenin titer can drive young bees to become extremely precocious foragers could imply that vitellogenin is the primary switch signal. At this young age, downregulation of vitellogenin gene activity apparently had little effect on the JH titer. As this unexpected finding stands in contrast with previous results on the vitellogenin/JH interaction at a later age, when bees normally become foragers, we propose a three-step sequence in the constellation of physiological parameters underlying behavioral development. David Santos Marco Antonio and Karina Rosa Guidugli-Lazzarini contributed equally to the present study.     

Determination of 129I/127I in aerosol samples in Seville (Spain)

In this work we present results of the (129)I/(127)I ratio in aerosols of Seville, Southwest of Spain (37.4 degrees N,6 degrees W). A radiochemical method is applied to extract the iodine from the aerosols and prepare samples to be measured by accelerator mass spectrometry (AMS) at the ETH facility in Zürich. We have found the possibility of monitoring the (129)I/(127)I isotopic ratio on a two-days basis with sensitivities in the order of 10(4)-10(5) atoms (129)I/m(3), and values of 10(-8)-10(-9) for the isotopic ratio.     

Adaptation strategies of the corallimorpharian <Emphasis Type="Italic">Rhodactis rhodostoma</Emphasis> to irradiance and temperature

Corallimorpharians may dominate some habitats on coral reefs and compete with stony corals for access to light, yet little is known concerning their photosynthetic traits. At Eilat in the northern Red Sea, we observed that the abundance of individuals of the corallimorpharian Rhodactis rhodostoma decreased significantly with depth on the reef slope. Field and laboratory experiments revealed that they employ several mechanisms of photoadaptation to high irradiance on the shallow reef flat. Their endosymbiotic microalgae (zooxanthellae) varied significantly in both abundance and chlorophyll content with level of irradiance. Use of a diving pulse amplitude modulated fluorometer revealed that the zooxanthellae of R. rhodostoma effectively disperse excess light energy by expressing significantly higher values of non-photochemical quenching and maximum excitation pressure on photosystem II when experimentally exposed to high light (HL) versus low light (LL). Host corallimorpharian tissues mediated this response by shielding the algal symbionts from high irradiance. The endoderm of host tentacles thickened significantly and microalgal cells were located further from the mesoglea in HL than in LL. The clades of zooxanthellae hosted by the corallimorpharians also varied with depth. In shallow water, all sampled individuals hosted clade C zooxanthellae, while in deep water the majority hosted clade D. The photosynthetic output of individuals of R. rhodostoma was less affected by HL than was that of a stony coral examined. When exposed to both high temperature (HT) and HL, individuals of R. rhodostoma reduced their maximum quantum yield, but not when exposed to HL at low temperature (LT). In contrast, colonies of the scleractinian coral Favia favus reduced their photosynthetic output when exposed to HL in both temperature regimes. After 2 weeks of HT stress, R. rhodostoma polyps appeared to bleach completely but re-established their zooxanthella populations upon return to ambient temperature. We conclude that mechanisms of photoadaptation to high irradiance employed by both the endosymbiotic zooxanthellae and host corallimorpharians may explain in part the abundance of R. rhodostoma on some shallow reef flats. The ability to survive for weeks at HT while bleached also may allow corallimorpharians to repopulate shallow reef areas where scleractinians have been killed by thermal stress. B. Kuguru and G. Winters contributed equally to this work.     

Strong effects of various incidence and observation angles on spectrometric assessment of plumage colouration in birds

The assessment of plumage colouration has become a common procedure in many ornithological studies, especially after the discovery of differences between avian and human visual systems, namely the avian ability to perceive ultraviolet wavelengths. There are many techniques available for plumage colour assessment. Nevertheless, unidirectional reflectance spectrometry seems actually to be the method of choice and is used in most studies. The active avian visual communication skills, the physical characteristics of the plumage surface and the birds’ body shape prompted us to study plumage colouration with different angles of incidence and observation by bidirectional reflectance spectrometry. In this study, we explore the effect of different angles of incidence and observation, on a single plane of incidence, on the reflectance spectrometric assessment of five differently coloured body regions of the blue fronted Amazon parrot (Amazona aestiva). Measurements were made using a AVS-USB2000 spectrometer with a DH-2000 light source and two different reflection probes (bifurcated fibre optic probe and a specially designed fibre holder). The results of this study illustrate clear angle dependence of colour parameters in differently coloured non-iridescent plumage regions of the blue fronted Amazon parrot. Our results may have direct implications on the observed transmitted information of display and its associated predation risk (trade-off) in birds, but also in other animals. Moreover, the results show that unidirectional reflectance spectrometry alone may be a rather limited procedure to quantify and compare true colour of a complex surface such as birds’ plumage. Therefore, slight but behavioural important characteristics of plumage pattern may remain undiscovered with this method.     

Speciation as a screening tool for the determination of heavy metal surface water pollution in the Guadiamar river basin

The Guadiamar river basin has traditionally received pollutants from two main sources: in its northern section of mining origin, and in its southern section (next to Do?ana National Park) from urban-industrial and agricultural sources. In April 1998, the spill of 6 million m3 of mining wastes (acidic waters and sludge) severely polluted the Guadiamar river basin with heavy metals, which caused serious damage to the local ecosystem. There is a direct association between the physicochemical speciation of an element and its toxicity, biological activity, bioavailability, solubility, etc. This work describes a distribution study of the metals Zn, Cd, Pb and Cu by speciation analysis of surface waters in eleven sampling points of the Guadiamar river basin. Four metal fractions were determined using anodic stripping voltammetry: labile metal forms, H+ exchangeable metal forms, strongly inert forms (associated with organic and inorganic matter in solution), and forms associated with suspended matter. Total concentrations in surface waters followed the trend Zn > Cu > Pb > Cd. The speciation study showed that Zn and Cd were present to a large extent in available forms (labile and H+ exchangeable), while Pb and Cu were found mostly in the less available forms (strongly inert). Moreover, the available forms were found in the northern section (mining pollution) and the strongly inert forms in the southern section (urban, industrial and agricultural pollution). These results can illustrate the potential value of speciation to discern between different sources of pollution.     

Techniques of remote sensing applied to the environmental analysis of part of an aquifer located in the São José dos Campos Region sp,Brazil

The anthropogenic activity on the surface can modify and introduce new mechanisms of recharging the groundwatersystem, modifying the tax, the frequency and the quality ofrecharge of underground waters. The understanding of thesemechanisms and the correct evaluation of such modifications arefundamental in determining the vulnerability of groundwatercontamination. The groundwater flow of the South ParaíbaCompartment, in the region of São José dos Campos, São Paulo, is directly related to structural features of theTaubaté Basin and, therefore, the analysis of its behaviourenhances the understanding of tectonic structure. The methodologyadopted for this work consists in pre-processing and processing of the satellite images, visual interpretation of HSI products, field work and data integration. The derivation of the main structural features was based on visual analysis of the textureelements of drainage, and the relief in sedimentary and crystalline rocks. Statistical analysis of the feature densitiesand the metric-geometric relations between the analysed elementshave been conducted. The crystalline rocks, on which the sediments were laying, conditions and controls the structural arrangement of sedimentary formations. The formation of the SouthParaíba Grabén is associated with Cenozoic distensive movement which reactivated old features of crust weakness and generated previous cycles with normal characteristics. The environmental analysis is based on the integration of the existing methodology to characterise vulnerability of an universal pollutant and density fracture zone. The digital integration was processed using GIS (Geographic Information System) to delineate five defined vulnerability classes. The hydrogeological settings were analysed in each thematic map and,using fuzzy logic, an index for each different vulnerability class was compiled. Evidence maps could be combined in a seriesof steps using map algebra.     

Sugarcane straw management for bioenergy: effects of global warming on greenhouse gas emissions and soil carbon storage

Mitigation and Adaptation Strategies for Global Change - Global warming can intensify the soil organic matter (SOM) turnover, damaging soil health. Crop residues left on the soil are important to...