Coralligène formations in the eastern Mediterranean Sea: Morphology, distribution, mapping and relation to fisheries in the southern Aegean Sea (Greece) based on high-resolution acoustics

Coralline algae are one of the most important constructors of biogenic habitats. In the Mediterranean Sea, the dominant coralline algae species form crusts comprising formations known as coralligène, considered as very important fishing grounds by fishermen. Due to the destructive effect of fishing gear activities over coralligène, these formations were recently protected from the use of active benthic gears by the EU 1967/2006 Mediterranean fisheries management Regulation. However, the lack of maps and information on their distribution makes the effective application of these measures impossible. The present publication contributes to the mapping of coralligène in the southern Aegean Sea (eastern Mediterranean), and to the study of coralline algae formation morphology, distribution, development conditions and relation to fisheries using a combination of single-beam echo sounder, sidescan sonar, sub-bottom profiler recordings and biological and sedimentological ground-truthing techniques. The coralligène formations were recognized as two distinct acoustic signatures of localized backscatter facies distinguishable from other hard substrate reflectors at depths ranging from 55.9 to 114.0 m, but mainly between 70 and 90 m. Two types of formations were identified: minute reefs 0.5-2.5 m in height and superficial layer formations no more than 0.2 m thick over the substrate. The seismic profiles revealed a cavernous internal structure of the minute reefs and recorded their development on both hard and soft substrates. The distribution of formations was contagious, creating aggregations. The finding of superficial layer formations and coralline shreds around minute coralligène reefs indicated that the former could be an intermediate development type between isolated small coralline pebbles, rhodoliths, and minute reefs. Regarding the development conditions, sidescan sonar imagery indicated that the optimal conditions for the establishment and development of coralligène formations are medium intensity currents. Concerning human activity over coralligène, trawl traces were recorded near but not over minute reefs and both near and crossing superficial layer type aggregations, while a submarine cable was also recorded among minute reefs. The mapping of coralligène aggregation areas is essential for the application of the EU Regulation and the protection of this important marine habitat.     

Scattered dose to radiosensitive organs and associated risk for cancer development from head and neck radiotherapy in pediatric patients

The purpose of this study was to measure the scattered dose to out-of-field organs from head and neck radiotherapy in pediatric patients and to estimate the risk for second cancer induction to individual organs. Radiotherapy for thalamic tumor, brain tumor, acute leukemia and Hodgkin's disease in the neck region was simulated on 5 and 10-year-old pediatric phantoms with a 6 MV photon beam. The radiation dose to thyroid, breast, lung, stomach, ovaries, bladder, liver, uterus, prostate and colon was measured using thermoluminescent dosimeters. The methodology, provided by the BEIR VII report was used for the second cancer risk estimations. Peripheral dose range for a simulated 5-year-old patient was 0.019%–1.572% of the given tumor dose. The corresponding range at the advanced patient age was reduced to 0.018%–1.468%. The second cancer risk per fraction for male patients varied from 3 to 215 per 1,000,000 patients depending upon the age at the time of exposure, primary cancer site and organ scattered dose. The corresponding risk for females was 1–1186 per 1,000,000 patients. The higher risk values were found for breast, thyroid and lung cancer development. The current data concerning the risk magnitude for developing subsequent neoplasms to various out-of-field organs may be of value for health care professionals in the follow-up studies of childhood cancer survivors.     

Functional characterization of the histidine kinase of the E. coli two-component signal transduction system AtoS–AtoC

The Escherichia coli AtoS–AtoC two-component signal transduction system regulates the expression of the atoDAEB operon genes, whose products are required for short-chain fatty acid catabolism. In this study purified his-tagged wild-type and mutant AtoS proteins were used to prove that these proteins are true sensor kinases. The phosphorylated residue was identified as the histidine-398, which was located in a conserved Η-box since AtoS carrying a mutation at this site failed to phosphorylate. This inability to phosphorylate was not due to gross structural alterations of AtoS since the H398L mutant retained its capability to bind ATP. Furthermore, the H398L mutant AtoS was competent to catalyze the trans-phosphorylation of an AtoS G-box (G565A) mutant protein which otherwise failed to autophosphorylate due to its inability to bind ATP. The formation of homodimers between the various AtoS proteins was also shown by cross-linking experiments both in vitro and in vivo.     

Xanthan gum and ethanol production by Xanthomonas campestris and Zymomonas mobilis from peach pulp

The wild type of Xanthomonas campestris and a mutant strain of Zymomonas mobilis CP4, tolerant to sucrose up to 40% (w/v), were used to produce either xanthan gum or ethanol, respectively, from peach pulp supplemented with different salts. Both bacteria grew well (2.7 mg/ml for X. campestris and 1.45 mg/ml for Z. mobilis) in fine peach pulp and the production of xanthan gum or ethanol was 0.1–0.2 g/l or 110 g/l, respectively.     

The inhibition of the serum-stimulated increase of ornithine decarboxylase by ionophores and local anesthetics

The addition of fresh serum-containing growth medium to L1210 mouse leukemic cells in culture resulted in a 5-fold increase in ornithine decarboxylase (l-ornithine carboxy-lyase, EC 4.1.1.17) activity. The presence of microtubule disrupting agents (colchine, vinblastine) or cations (5–10 mM K⁺, Na⁺ or Mg²⁺) abolishes this increase of ornithine decarboxylase activity (Chen, K.Y., Heller, J.S. and Canellakis, E.S. (1976) Biochem. Biophys. Res. Commun. 70, 212–219). Based on these observations we proposed that fluctuation in cellular cation concentrations may act as a link between the membrane structure and ornithine decarboxylase. To test this proposal, we studied the effects of selective membrane perturbing agents such as ionophores and local anesthetics, on the serum-stimulated increase of ornithine decarboxylase activity in L1210 cells. Among the six inonophores tested, valinomycin was the most potent one, with I₅₀ value (concentration that gives 50% inhibition of orthinine decarbocylase activity) of 6·10^?9 M. Dibucaine and tetracaine were also effective inhibitors at 10^?4?10^?5 M. The I₅₀ values of valinomycin on the protein synthesis and RNA synthesis, however, were greater than 1·10^?6 M. These results substantiate the notion that ornithine decarboxylase activity can be regulated at plasma membrane level and such regulation is related to the perturbation of cellular cation pools.     

Single-shot phase contrast microscopy using polarisation-resolved differential phase contrast

We present a robust, low-cost single-shot implementation of differential phase microscopy utilising a polarisation-sensitive camera to simultaneously acquire four images from which phase contrast images can be calculated. This polarisation-resolved differential phase contrast (pDPC) microscopy technique can be easily integrated with fluorescence microscopy.