Biological Breathalyzer

The aim of this research is the construction of a biological breathalyzer through synthetic biology, specifically through use of the metabolic pathways of a species of the Pichia taxa. The yeast utilized is able to metabolize both ethanol and methanol. However, when both ethanol and methanol are present, the yeast prefers to metabolize ethanol such that an AOX gene is not expressed because the first known by-product of methanol metabolism is the AO enzyme from the AOX gene. The AOX gene promoter is fused with a fluorescence protein gene so expression of the AOX gene can be visually detected. When the cell is supplied with both ethanol and methanol, the amount of time before fluorescence will correspond to the amount of ethanol given to the cell. In this way, the concentration of ethanol can be determined

Construction and Testing of a Biological Breathalyzer

The ultimate goal of this research was the construction of a biological breathalyzer using methods of synthetic biology. The metabolic pathways of Pichia taxa were utilized for this research. This yeast is able to metabolize both ethanol and methanol present in the environment. The first known by-product of methanol metabolism is the AO enzyme from the AOX gene. When both ethanol and methanol are present, the yeast preferentially metabolizes ethanol and the AOX gene is not expressed. By fusing the AOX gene promoter with a fluorescence protein gene, the expression of the AOX gene may be visually detected. When the organism is supplied with both ethanol and methanol, the amount of time before fluorescence will correspond to the amount of ethanol fed to the cell. In this way, the concentration of ethanol can be determined

Influence of Surface Roughness Spatial Variability and Temporal Dynamics on the Retrieval of Soil Moisture from SAR Observations

Radar-based surface soil moisture retrieval has been subject of intense research during the last decades. However, several difficulties hamper the operational estimation of soil moisture based on currently available spaceborne sensors. The main difficulty experienced so far results from the strong influence of other surface characteristics, mainly roughness, on the backscattering coefficient, which hinders the soil moisture inversion. This is especially true for single configuration observations where the solution to the surface backscattering problem is ill-posed. Over agricultural areas cultivated with winter cereal crops, roughness can be assumed to remain constant along the growing cycle allowing the use of simplified approaches that facilitate the estimation of the moisture content of soils. However, the field scale spatial variability and temporal variations of roughness can introduce errors in the estimation of soil moisture that are difficult to evaluate. The objective of this study is to assess the impact of roughness spatial variability and roughness temporal variations on the retrieval of soil moisture from radar observations. A series of laser profilometer measurements were performed over several fields in an experimental watershed from September 2004 to March 2005. The influence of the observed roughness variability and its temporal variations on the retrieval of soil moisture is studied using simulations performed with the Integral Equation Model, considering different sensor configurations. Results show that both field scale roughness spatial variability and its temporal variations are aspects that need to be taken into account, since they can introduce large errors on the retrieved soil moisture values

Acehnese reefs in the wake of the Asian tsunami

The Sumatra-Andanaman tsunami was one of the greatest natural disasters in recorded human history. Here, we show that on the northwest coast of Aceh, Indonesia, where the tsunami was most ferocious [1], the damage to corals, although occasionally spectacular, was surprisingly limited. We detected no change in shallow coral assemblages between March 2003 and March 2005, with the exception of one site smothered by sediment. Direct tsunami damage was dependent on habitat and largely restricted to corals growing in unconsolidated substrata, a feature unique to tsunami disturbance. Reef condition, however, varied widely within the region and was clearly correlated with human impacts prior to the tsunami. Where fishing has been controlled, coral cover was high. In contrast, reefs exposed to destructive fishing had low coral cover and high algal cover, a phase shift the tsunami may exacerbate with an influx of sediments and nutrients [2]. Healthy reefs did not mitigate the damage on land. Inundation distance was largely determined by wave height and coastal topography. We conclude that although chronic human misuse has been much more destructive to reefs in Aceh than this rare natural disturbance [3], human modification of the reef did not contribute to the magnitude of damage on land