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Selected AbstractsA 3-D Graphical Database System for Landfill Operations Using GPSCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 5 2002H. Ping Tserng Landfill space is an important commodity for landfill companies. It is desirable to develop an efficient tool to assist space management and monitor space consumption. When recyclable wastes or particular waste materials need to be retrieved from the landfill site, the excavation operations become more difficult without an efficient tool to provide waste information (i.e., location and type). In this paper, a methodology and several algorithms are proposed to develop a 3-D graphical database system (GDS) for landfill operations. A 3-D GDS not only monitors the space consumption of a landfill site, but can also provide exact locations and types of compacted waste that would later benefit the landfill excavation operations or recycling programs after the waste is covered. [source] Deuterostome evolution: early development in the enteropneust hemichordate, Ptychodera flavaEVOLUTION AND DEVELOPMENT, Issue 6 2001Jonathan Q. Henry SUMMARY Molecular and morphological comparisons indicate that the Echinodermata and Hemichordata represent closely related sister-phyla within the Deuterostomia. Much less is known about the development of the hemichordates compared to other deuterostomes. For the first time, cell lineage analyses have been carried out for an indirect-developing representative of the enteropneust hemichordates, Pty- chodera flava. Single blastomeres were iontophoretically labeled with DiI at the 2- through 16-cell stages, and their fates followed through development to the tornaria larval stage. The early cleavage pattern of P. flava is similar to that of the direct-developing hemichordate, Saccoglossus kowalevskii, as well as that displayed by indirect-developing echinoids. The 16-celled embryo contains eight animal "mesomeres," four slightly larger "macromeres," and four somewhat smaller vegetal "micromeres." The first cleavage plane was not found to bear one specific relationship relative to the larval dorsoventral axis. Although individual blastomeres generate discrete clones of cells, the appearance and exact locations of these clones are variable with respect to the embryonic dorsoventral and bilateral axes. The eight animal mesomeres generate anterior (animal) ectoderm of the larva, which includes the apical organ; however, contributions to the apical organ were found to be variable as only a subset of the animal blastomeres end up contributing to its formation and this varies from embryo to embryo. The macromeres generate posterior larval ectoderm, and the vegetal micromeres form all the internal, endomesodermal tissues. These blastomere contributions are similar to those found during development of the only other hemichordate studied, the direct-developing enteropneust, S. kowalevskii. Finally, isolated blastomeres prepared at either the two- or the four-cell stage are capable of forming normal-appearing, miniature tornaria larvae. These findings indicate that the fates of these cells and embryonic dorsoventral axial properties are not committed at these early stages of development. Comparisons with the developmental programs of other deuterostome phyla allow one to speculate on the conservation of some key developmental events/mechanisms and propose basal character states shared by the ancestor of echinoderms and hemichordates. [source] Analysis of the interaction of 16S rRNA and cytoplasmic membrane with the C-terminal part of the Streptococcus pneumoniae Era GTPaseFEBS JOURNAL, Issue 21 2001Julie Qi Hang Era, an essential GTPase, plays a regulatory role in several cellular processes. The Era protein of Streptococcus pneumoniae has recently been shown to bind to 16S rRNA and the cytoplasmic membrane. However, exact locations of Era responsible for RNA- and membrane-binding were unknown. To identify the regions in Era that interact with the RNA and membrane, the C-terminal part of S. pneumoniae Era was systematically deleted while the N-terminal part, responsible for the GTPase activity of the protein, was kept intact. The resulting truncated Era proteins were purified and characterized. The C-terminal deletion of 9 or 19 amino-acid residues did not affect 16S rRNA-binding activity while further deletions of the C-terminus (29,114 amino-acid residues) abolished the activity. These results indicate that the integrity of the putative KH domain of Era, spanning the amino-acid residues between ,,22,83 from the C-terminus, is required for 16S rRNA-binding. Furthermore, the Era proteins with a deletion up to 45 residues from the C-terminus retained membrane-binding activity, but longer deletions significantly reduced the activity. These results indicate that part of the putative KH domain is also required for membrane-binding. Thus, these results indicate for the first time that the regions critical for the membrane- and 16S rRNA-binding activities of Era overlap. The era gene with a deletion of 9 or 19 codons from its 3, terminus complemented an Escherishia coli mutant strain deficient in Era production whereas the genes with longer deletions failed to do so, thereby indicating that the KH domain is essential for Era function. Taken together, the results of this study indicate that the putative KH domain is required for 16S rRNA-binding activity and that part of the KH domain is also required for membrane-binding activity. The results also suggest that the interaction between Era and 16S rRNA is essential for bacterial growth. [source] Presence and distribution of PAHs, PCBs and DDE in feed and sediments under salmon aquaculture cages in the Bay of Fundy, New Brunswick, CanadaAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2005J. Hellou Abstract 1.Wastes from feed and faeces can result in the deposition of contaminants in sediments around aquaculture sites. Five types of feed pellet, a commercial fish oil and 76 sediment samples collected under and up to 100 m away from salmon aquaculture cages in the south-western Bay of Fundy between 1998 and 2000 were analysed for polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and chlorinated pesticides. 2.Five alkylated naphthalenes (aNAs) were consistently detected in fish oil (116,180 ng g,1, per aNA), in pellets (25,51 ng g,1, dry weight, per aNA), and sediments (<1,45 ng g,1, dry weight, per aNA). Other PAHs were detected at variable levels in feed or in sediments. 3.IUPAC congener 153 (a PCB) and p,p,-dichlorodiphenyldichloroethylene (p,p,-DDE) were detected more frequently than other chlorinated targets in oil (108 ng g,1 and 176 ng g,1 respectively), feed (<1,14 ng g,1 and 1.7,28.2 ng g,1 respectively) and sediments (<0.08,3 ng g,1 and <0.5,7 ng g,1 respectively). 4.Trends were observed during the first year of sediment sampling (1998), with higher organic carbon, PCBs and p,p,-DDE levels below the cages than 50 m away. The PAHs other than aNA showed an opposite trend with distance. In 1999, levels of p,p,-DDE and PCBs were somewhat reduced under the cages, but were detected up to 100 m away from the cages. 5.Levels of aNA tended to be higher at some sites in 1999 relative to 1998, reflecting variability in feed and/or differential transport or degradation of contaminants relative to the environmental background. When detected, mean levels of PCBs and DDE were 2,10 times lower in 2000 than in 1999, and PAHs were 30,40% lower in 2000 than in 1999. 6.Interpretation of the results is done cautiously, since the exact locations of the sites sampled is only known to an intermediate facilitating the work between farmers and scientists. Levels of contaminants are compared with international results, interpreted relative to potential toxicity, uptake from feed, from deposited sediments, and in the framework of an aquaculture decision-support system published recently. Copyright © 2005 John Wiley & Sons, Ltd. [source] | ||||||||||