Conditions for effective removal of pyrene from an artificially contaminated soil using Pseudomonas aeruginosa 57SJ rhamnolipids

The efficacy of a new rhamnolipid biosurfactants mixture to enhance the removal of pyrene from a soil artificially contaminated was investigated. The molar solubilization ratio (MSR) and the partition coefficient between the micelles and water (log K(m)) were found to be 7.5 x 10(-3) and 5.7, respectively. From soil column studies, the pyrene removal increased linearly with the concentration of the injected biosurfactants solution above the effective critical micellar concentration (0.4 g L(-1)). Flushing with a 5.0 g L(-1) biosurfactants solution increased the pyrene concentration in the effluent by 178 times. At high biosurfactants' concentrations (2.5 and 5.0 g L(-1)), the cumulative pyrene recovery reached 70%. This pyrene remobilization takes place independently of the soil organic carbon solubilization. This study provides a combination of batch and column experiments in order to find the conditions for effective soil remediation using a new rhamnolipids mixture.     

Diversity pattern and spatial scale: a study of a tropical rain forest of Malaysia

Scale is emerging as one of the critical problems in ecology because our perception of most ecological variables and processes depends upon the scale at which the variables are measured. A conclusion obtained at one scale may not be valid at another scale without sufficient knowledge of the scaling effect, which is also a source of misinterpretation for many ecological problems, such as the design of reserves in conservation biology.This paper attempts to study empirically how scaling may affect the spatial patterns of diversity (tree density, richness and Shannon diversity) that we may perceive in tropical forests, using as a test-case a 50 ha forest plot in Malaysia. The effect of scale on measurements of diversity patterns, the occurrence of rare species, the fractal dimension of diversity patterns, the spatial structure and the nearest-neighbour autocorrelation of diversity are addressed. The response of a variable to scale depends on the way it is measured and the way it is distributed in space.We conclude that, in general, the effect of scaling on measures of biological diversity is non-linear; heterogeneity increases with the size of the sampling units, and fine-scale information is lost at a broad scale. Our results should lead to a better understanding of how ecological variables and processes change over scale.     

Limestone surfaces in built-up environment as indicators of atmospheric pollution

The concentration of sulphate on limestone surfaces of the external walls of churches in Malta is shown to be related to their position and distance from a power station, the main local point source of sulphur dioxide pollution. Limestone powder collected from these surfaces was examined for the presence of particles which, under low-power optical microscopy, appear as shiny black amorphous bodies which were interpreted as soot particles; the abundance of these bodies was expressed as a black particle count (BPC). The degree of sulphation and BPC were shown to be correlated with each other and both appeared to be strongly dependent on the prevailing wind. The BPC contour map indicated an important contribution to the parameter from vehicular traffic. It is suggested that the degree of sulphation and BPC of limestone surfaces from the built environment should function as environmental indicators of the relative air quality with respect to SO₂ and soot pollution. This data is possibly more accurately representative of the relative long-term air-quality status of different areas of habitation than that deduced from single or episodic measurements of atmospheric pollutant levels.     

Reproductive plasticity in bumblebee workers (<Emphasis Type="Italic">Bombus terrestris</Emphasis>)—reversion from fertility to sterility under queen influence

Worker sterility in the bumblebee Bombus terrestris is conditional and is linked to the social development of the colony. Workers refrain from reproducing or overtly challenging the queen until gyne production has initiated, at the so-called competition point (CP). It is not known whether this behavior is hard-wired or workers show reproductive plasticity. It also remains unclear whether worker reproductive decision is under queen and/or worker control. In this study, we tested worker reproductive plasticity in an attempt to assess whether and under which conditions worker sterility/fertility are reversible. We introduced egg-laying workers into colonies with different social structures for 1 week then monitored their reproductive status. We revealed a remarkable reproductive plasticity in the introduced workers that was social-condition-dependent. In the presence of a pre-CP queen, the introduced workers reverted to sterility, whereas in the presence of a post-CP queen, such workers remained egg-layer. Reversion to sterility does not occur when direct contact with the queen is prevented, as the introduced workers remained egg-layer in the queenright colonies with a confined queen. Egg-laying workers that were introduced into queenless colonies mostly maintained their fertility regardless of colony social phase. This shows that worker transition from cooperative to selfish behavior is reversible depending on the social context.     

Prenatal diagnosis of trisomy 10 p in a twin pregnancy

A twin pregnancy with trisomy 10 p due to a paternal 10;12 translocation is reported. The prenatal diagnosis steps followed in twin pregnancies are reviewed and the concordant features of trisomy 10 p seen in both fetuses confirm previous reports on the clinical features of this chromosomal defect.     

Are breaking waves,bores, surges and jumps the same flow?

The flow structure in the aerated region of the roller generated by breaking waves remains a great challenge to study, with large quantities of entrained air and turbulence interactions making it very difficult to investigate in details. A number of analogies were proposed between breaking waves in deep or shallow water, tidal bores and hydraulic jumps. Many numerical models used to simulate waves in the surf zone do not implicitly simulate the breaking process of the waves, but are required to parameterise the wave-breaking effects, thus relying on experimental data. Analogies are also assumed to quantify the roller dynamics and the energy dissipation. The scope of this paper is to review the different analogies proposed in the literature and to discuss current practices. A thorough survey is offered and a discussion is developed an aimed at improving the use of possible breaking proxies. The most recent data are revisited and scrutinised for the use of most advanced numerical models to educe the surf zone hydrodynamics. In particular, the roller dynamics and geometrical characteristics are discussed. An open discussion is proposed to explore the actual practices and propose perspectives based on the most appropriate analogy, namely the tidal bore.     

Global effects of extreme temperatures on wild bumblebees

Climate plays a key role in shaping population trends and determining the geographic distribution of species because of limits in species’ thermal tolerance. An evaluation of species tolerance to temperature change can therefore help predict their potential spatial shifts and population trends triggered by ongoing global warming. We assessed inter- and intraspecific variations in heat resistance in relation to body mass, local mean temperatures, and evolutionary relationships in 39 bumblebee species, a major group of pollinators in temperate and cold ecosystems, across 3 continents, 6 biomes, and 20 regions (2386 male specimens). Based on experimental bioassays, we measured the time before heat stupor of bumblebee males at a heatwave temperature of 40 °C. Interspecific variability was significant, in contrast to interpopulational variability, which was consistent with heat resistance being a species-specific trait. Moreover, cold-adapted species are much more sensitive to heat stress than temperate and Mediterranean species. Relative to their sensitivity to extreme temperatures, our results help explain recent population declines and range shifts in bumblebees following climate change.