Bibliometric Analysis of Research Hotspots Related to Marine Oil Spill Accidents in the Environmental Field Based on Web of Science.

ABSTRACT: Objective To conduct bibliometric analysis of the relevant literature in the environmental field published from 1982 to 2018 collected by the Web of Science citation database and further explore the frontier research dynamics and hotspots in the environmental field. Methods The word "oil spill*" was used as the subject term for retrieval. A knowledge map of hotspots in oil spill research was built through software VOSviewer and the clustering relations between them were explored. The frequency and relevance of the keywords in the corresponding literature were obtained by the matrix of keywords built through the Thomson Data Analyzer （TDA） software. Results The four main research hotspots of marine oil spill pollution were oil spill numerical simulation and model prediction, oil spill exposure toxicity and risk assessment, oil spill component and source analysis and oil spill pollution characteristics and treatment. Conclusion The study analyzes the main content of the four research hotspots and the current research progress and provides scientific basis for further understanding of the mechanism of marine oil spill occurrence, migration and transformation, implementation of oil spill treatment and repair as well as more accurate assessment of eco-environment damage.

Cloning and expression of delta-endotoxin gene of Bacillus thuringiensis in Escherichia coli.

Fragments (larger than 4 kb) of partially Sau 3AI-digested plasmid DNA from Bacillus thuringiensis subsp. kenyae 7404 and kurstaki HD-1 were cloned into the BamH I site of pBR322. Four transformants, containing the corresponding delta-endotoxin gene and producing proteins that reacted with antiserum against crystalline protein, were selected on the basis of results from in situ colony hybridization, radioimmunologic screening, and Western blot analysis. Three of those tested, i.e., the lysates of one transformant (TK89) carrying the delta-endotoxin gene of B.t. 7404 and two transformants (TH12 and TH48) carrying the delta-endotoxin gene of HD-1, were toxic for tobacco budworm (Heliothis assulta) and armyworm (Leucania separata Walker) caterpillars. This is the first report on cloning of the delta-endotoxin gene from B.t. subsp. kenyae, which is different in serotype from the well-studied subsp. kurstaki.