Isolation of pigment cell specific genes in the sea urchin embryo by differential macroarray screening

New secondary mesenchyme specific genes, expressed exclusively in pigment cells, were isolated from sea urchin embryos using a differential screening of a macroarray cDNA library. The comparison was performed between mRNA populations of embryos having an expansion of the endo-mesodermal territory and embryos blocked in secondary mesenchyme specification. To be able to isolate transcripts with a prevalence down to five copies per cell, a subtractive hybridization procedure was employed. About 400 putative positive clones were identified and sequenced from the 5' end. Gene expression analysis was carried out on a subset of 66 clones with real time quantitative PCR and 40 clones were positive. This group of clones contained sequences highly similar to: the transcription factor glial cells missing (gcm); the polyketide synthase gene cluster (pks-gc); three different members of the flavin-containing monooxygenase gene family (fmo); and a sulfotransferase gene (sult). Using whole mount in situ hybridization, it was shown that these genes are specifically expressed in pigment cells. A functional analysis of the S. purpuratus pks and of one S. purpuratus fmo was carried out using antisense technology and it was shown that their expression is necessary for the biosynthesis of the sea urchin pigment echinochrome. The results suggest that S. purpuratus pks, fmo and sult could belong to a differentiation gene battery of pigment cells

Rethinking the Patch Test for Phase Measuring Bathymetric Sonars

While conducting hydrographic survey operations in the Florida Keys, NOAA Ship Thomas Jefferson served as a test platform for the initial operational implementation of an L-3 Klein HydroChart 5000 Swath Bathymetry Sonar System1 , a hull-mounted phase measuring bathymetric sonar (PMBS). During the project it became apparent that the traditional patch test typically utilized for multibeam echosounder (MBES) systems was poorly suited to the HydroChart – and perhaps other PMBS systems as well. These systems have several inherent characteristics that make it difficult to isolate and subsequently solve for biases under the traditional patch test paradigm: presence of a nadir gap, wide swaths (typically greater than 6 times water depth), and relatively poor object-detection capability in the outer swath. After “rethinking” the patch test to account for these characteristics, the authors propose a new patch test paradigm that is better suited to the HydroChart and other PMBS systems

Screw pile design optimisation under tension in sand

Many applications in offshore engineering, such as floating or jacket-founded wind turbines or wave energy converters, require a significant uplift capacity of their foundations to be kept in place. Straight-shafted or suction piles in sands have a limited uplift capacity as they resist by friction only. In contrast, screw piles or screw anchors are a promising solution which provides a similar capacity to plate anchors and does not generate disturbance for marine mammals (e.g. from pile driving operations). The optimisation of the screw pile design does not rely only on the geotechnical assessment of the uplift capacity based on soil strength, but also on operational (installation requirements) and structural (helix bending, core section stress, limiting steel plate thick-ness) constraints. This paper develops a methodology for the design optimisation of screw piles under pure ten-sion in sand, incorporating all of these constraints, based on simplified analytical or semi-analytical approaches. The results show that the uplift capacity provided by an optimised screw pile is able to meet the needs of the offshore industry, across a range of soil densities and different applications (jacket foundation pile or tension leg platform anchor), providing that adequate installation plant could be dev

Law and English Railway Capitalism: 1825-1875

Book review of Law and English Railway Capitalism: 1825-1875 by R.W. Kostal and published by Clarendon Press (Oxford), 1994. (417 pp.