Sponge alleleochemical induces ascidian settlement but inhibits metamorphosis

Secondary metabolites synthesised by sessile invertebrates appear to play a role in creating and maintaining space on hard substrata by repelling competitors. In this study, we investigated the responses of the larvae of the ascidian Herdmania curvata to haliclonacyclamine A (HA), the major component of a suite of cytotoxic alkaloids extracted from the sponge Haliclona sp. 628. Both Haliclona sp. 628 and Herdmania curvata inhabit the crest and slope of Heron Island Reef. High rates of settlement were induced in competent H. curvata larvae by a range of concentrations of HA, all lower than that naturally occurring in the sponge. HA did not induce precompetent larvae to settle. Although early metamorphosis of HA-induced larvae was normal, larvae exposed to all but the lowest concentration of HA were developmentally arrested after completion of tail resorption, at about 4 h after the initiation of metamorphosis. These postlarvae underwent extensive cellular necrosis within 24 h. We also demonstrate that the addition of a transcriptional inhibitor, actinomycin D, to larvae also causes inhibition of metamorphosis after tail resorption is completed. Analyses of incorporation of radiolabelled nucleotides to measure levels of transcription during normal development and after the addition of the transcriptional inhibitor indicate that there is a significant burst of transcriptional activity just after tail resorption is completed. Despite inhibiting metamorphosis at the same stage as actinomycin D, HA increases initial rates of RNA synthesis after induction of metamorphosis in a manner similar to that observed in normal postlarvae until the onset of cellular necrosis. We conclude that HA initially induces H. curvata larvae to settle and progress through early metamorphosis possibly by engaging the same pathway as other artificial and environmental cues but subsequently inhibits completion of metamorphosis, resulting in death of the postlarvae. Since HA does not affect overall transcription rates, it appears to disrupt another important developmental process during early metamorphosis.

Transfer of technology to China:A Scandinavian and European perspective

This paper examines the question of technology transfer from the perspective of techno-economic security and how companies respond to the possibility of losing competitive advantage through misappropriation or leakage. It explores transfers from Europe to China and addresses in particular the operations of Scandinavian companies within the context of the general picture for other European firms. Its point of departure is the authors' earlier research that looked at the motivations for transfer and the awareness of companies of techno-economic security issues. This has been supplemented by new data gathered by the authors from a number of Scandinavian companies in China. Specific actions have been identified and the ownership issue is introduced together with consideration of the role of the companies against the 'Ferdows' model. The analysis shows that the nature of the security question has changed together with the evolving context in which the companies are operating. In turn, the response of companies is contingent on a number of factors including the time horizon of the strategy for a unit in China and the nature of the strategy. It is also influenced by the form of ownership and management style in a particular organisation. © 2002 Elsevier Science Ltd. All rights reserved.

Settlement of fill with particular reference to opencast coal mining sites

A study of information available on the settlement characteristics of backfill in restored opencast coal mining sites and other similar earthworks projects has been undertaken. In addition, the methods of opencast mining, compaction controls, monitoring and test methods have been reviewed. To consider and develop the methods of predicting the settlement of fill, three sites in the West Midlands have been examined; at each, the backfill had been placed in a controlled manner. In addition, use has been made of a finite element computer program to compare a simple two-dimensional linear elastic analysis with field observations of surface settlements in the vicinity of buried highwalls. On controlled backfill sites, settlement predictions have been accurately made, based on a linear relationship between settlement (expressed as a percentage of fill height) against logarithm of time. This `creep' settlement was found to be effectively complete within 18 months of restoration. A decrease of this percentage settlement was observed with increasing fill thickness; this is believed to be related to the speed with which the backfill is placed. A rising water table within the backfill is indicated to cause additional gradual settlement. A prediction method, based on settlement monitoring, has been developed and used to determine the pattern of settlement across highwalls and buried highwalls. The zone of appreciable differential settlement was found to be mainly limited to the highwall area, the magnitude was dictated by the highwall inclination. With a backfill cover of about 15 metres over a buried highwall the magnitude of differential settlement was negligible. Use has been made of the proposed settlement prediction method and monitoring to control the re-development of restored opencase sites. The specifications, tests and monitoring techniques developed in recent years have been used to aid this. Such techniques have been valuable in restoring land previously derelict due to past underground mining.