The impact of coastal erosion on the archaeology of the Cyrenaican coast of Eastern Libya.

Coastal erosion in Cyrenaica (Eastern Libya) represents a major problem for archaeology and heritage management. The area is rich in archaeological sites, often understudied or not fully documented, but also has extensive stretches of vulnerable eroding coastline. This study demonstrates the extent and impact of erosion via shoreline change assessment at two spatial scales. Firstly, wide area assessment using shorelines extracted from a time-series of medium-resolution Landsat imagery. Secondly, site-specific assessment using recent and historic Very High Resolution (VHR) satellite imagery. In both cases, extracted shorelines at different timesteps were compared using the Digital Shoreline Analysis System (DSAS) tool to quantify rates and magnitudes of shoreline movement. The results show extensive zones of erosion at and around the key ancient harbour sites of Apollonia, Ptolemais and Tocra. They also suggest increased rates of coastal retreat in recent years, which is likely linked to anthropogenic actions such as sand mining and urbanization. Forecasts based on present-day shoreline change rates, coupled with ground-level documentation of the vulnerable shorelines is used to identify archaeological features and structures which will likely be progressively damaged or destroyed over the next 20 years. The ability to actively protect archaeological sites is unclear, but there is a clear need for mitigation in the form of enhanced awareness of environmental problems (e.g. caused by sand mining) and more intensive survey/documentation of sites and areas which will be lost in the coming years.

Engineering of CYP106A2 for steroid 9α- and 6ß-hydroxylation.

CYP 106A2 from Bacillus megaterium ATCC 13368 has been described as a 15ß-hydroxylase showing also minor 11α-, 9α- and 6ß-hydroxylase activity for progesterone conversion. Previously, mutant proteins with a changed selectivity towards 11α-OH-progesterone have already been produced. The challenge of this work was to create mutant proteins with a higher regioselectivity towards hydroxylation at positions 9 and 6 of the steroid molecule. 9α-hydroxyprogesterone exhibits pharmaceutical importance, because it is a useful intermediate in the production of physiologically active substances which possess progestational activity. Sixteen mutant proteins were selected from a library containing mutated proteins created by a combination of site-directed and saturation mutagenesis of active site residues. Four mutant proteins out of these catalyzed the conversion of progesterone to 9α-OH-progesterone as a main product. For further optimization site-directed mutagenesis was performed. The introduction of seven mutations (D217V, A243V, A106T, F165L, T89N, T247V or T247W) into these four mutant proteins led to 28 new variants, which were also used for an in vivo conversion of progesterone. The best mutant protein, F165L/A395E/G397V, showed a ten-fold increase in the selectivity towards progesterone 9α-hydroxylation compared with the wild type CYP106A2. Also 6ß-OH-progesterone is a pharmaceutically important compound, especially as intermediate for the production of drugs against breast cancer. For the rational design of mutant proteins with 6ß-selectivity, docking of the 3D-structure of CYP106A2 with progesterone was performed. The introduction of three mutations (T247A, A243S, F173A) led to seven new mutant proteins. Clone A243S showed the greatest improvement in 6ß-selectivity being more than ten-fold. Finally, an in vivo conversion of 11-deoxycorticosterone (DOC), testosterone and cortisol with the best five mutant proteins displaying 9α- or 6ß-hydroxylation, respectively, of progesterone was performed to investigate whether the introduced mutations also effected the conversion of other substrates.

Olfactory function in children assessed with psychophysical and electrophysiological techniques.

The olfactory information processing abilities of children undergo changes during early life. The aims of the present study were to describe these changes and to probe for their electrophysiological correlates. These aims were investigated in two experiments. In Experiment 1, responses of 146 subjects (3-12 years) were tested with psychophysical tools. Approximately 2/3 of the subjects completed the olfactory tests ("Sniffin' Sticks"). In Experiment 2, 12 additional subjects (3-10 years) were tested with electrophysiological tools. Event-related potentials (ERPs) were recorded in response to olfactory stimulation with H(2)S. Results from Experiment 1 indicated that data from the group of 3-5-year olds were very unreliable, with 44% of incomplete measures rendering the tests unsuitable for routine use with 3-5-year olds. From an age of 6 years on the results suggested that the development of olfactory function was well advanced with a significant increase found only for odor identification, but not for odor thresholds, or odor discrimination. Results from Experiment 2 indicated an increase of the P2 latency with age, although the small sample size has to be considered in the interpretation of these data. While more research is needed, these results may be interpreted such that children attach more meaning to odorous stimuli with age.