Altered MRP is associated with multidrug resistance and reduced drug accumulation in human SW-1573 cells.

We have analysed the contribution of several parameters, e.g. drug accumulation, MDR1 P-glycoprotein (P-gp), multidrug resistance-associated protein (MRP) and topoisomerase (topo) II, to drug resistance in a large set of drug-resistant variants of the human non-small-cell lung cancer cell line SW-1573 derived by selection with low concentrations of doxorubicin or vincristine. Selection with either drug nearly always resulted in MDR clones. The resistance of these clones could be explained by reduced drug accumulation and was associated with a decrease rather than an increase in the low MDR1 mRNA level. To test whether a decrease in MDR1 mRNA indirectly affected resistance in these cells, we introduced a MDR1-specific hammerhead ribozyme into wild-type SW-1573 cells. Although this led to a substantial reduction in MDR1 mRNA, it did not result in resistance. In all resistant clones we found an altered form of the multidrug resistance-associated protein (MRP), migrating slightly slower during SDS-polyacrylamide gel electrophoresis than MRP in parental cells. This altered MRP was also present in non-P-gp MDR somatic cell hybrids of the SW-1573 cells, demonstrating a clear linkage with the MDR phenotype. Treatment of crude cellular membrane fractions with N-glycanase, endoglycosidase H or neuraminidase showed that the altered migration of MRP on SDS-PAGE is due to a post-translational modification. There was no detectable difference in sialic acid content. In most but not all doxorubicin-selected clones, this MDR phenotype was accompanied by a reduction in topo II alpha mRNA level. No reduction was found in the clones selected with vincristine. We conclude from these results that selection of the SW-1573 cell line for low levels of doxorubicin or vincristine resistance, predominantly results in MDR with reduced drug accumulation associated with the presence of an altered MRP protein. This mechanism can be accompanied by other resistance mechanisms, such as reduced topo II alpha mRNA in case of doxorubicin selection

Effect of different rubber materials on husking dynamics of paddy rice

The conventional way to husk rice is to pass it between two rubber rollers that are rotating with a surface speed differential. The resulting normal pressure and shear stress causes the husk to be peeled away from the kernel. The process is suited to high-rice flow rates, but is energy intensive and can result in considerable wear to the surfaces of the rollers. The operating parameters for machines of this design are usually determined and set empirically. In this article, some experiments and calculations had been carried out in order to explore the mechanisms involved in husking rice grains using this method. A simple sliding friction rig with load cell and high-speed camera was used to observe the mechanisms that occur during husking. The husking performance of different rubbers was compared for changes in the applied normal load. It was found that grains rotate between the rubber counterfaces on initial motion before being husked. In addition, harder rubbers were found to husk a higher proportion of entrained grains at lower applied normal load. By measuring the coefficient of friction between rice and rubber samples, the shear force required to husk a given percentage of grains could be calculated and was shown to be constant regardless of rubber type. Based on the mechanism seen in the high-speed video, it was evident that there was a limiting shear stress that was the governing factor over the husked ratio

Effect of different rubber materials on husking dynamics of paddy rice

The conventional way to husk rice is to pass it between two rubber rollers that are rotating with a surface speed differential. The resulting normal pressure and shear stress causes the husk to be peeled away from the kernel. The process is suited to high-rice flow rates, but is energy intensive and can result in considerable wear to the surfaces of the rollers. The operating parameters for machines of this design are usually determined and set empirically. In this article, some experiments and calculations had been carried out in order to explore the mechanisms involved in husking rice grains using this method. A simple sliding friction rig with load cell and high-speed camera was used to observe the mechanisms that occur during husking. The husking performance of different rubbers was compared for changes in the applied normal load. It was found that grains rotate between the rubber counterfaces on initial motion before being husked. In addition, harder rubbers were found to husk a higher proportion of entrained grains at lower applied normal load. By measuring the coefficient of friction between rice and rubber samples, the shear force required to husk a given percentage of grains could be calculated and was shown to be constant regardless of rubber type. Based on the mechanism seen in the high-speed video, it was evident that there was a limiting shear stress that was the governing factor over the husked ratio

Population Dynamics and Diversity of Viruses, Bacteria and Phytoplankton in a Shallow Eutrophic Lake

We have studied the temporal variation in viral abundances and community assemblage in the eutrophic Lake Loosdrecht through epifluorescence microscopy and pulsed field gel electrophoresis (PFGE). The virioplankton community was a dynamic component of the aquatic community, with abundances ranging between 5.5 × 107 and 1.3 × 108 virus-like particles ml−1 and viral genome sizes ranging between 30 and 200 kb. Both viral abundances and community composition followed a distinct seasonal cycle, with high viral abundances observed during spring and summer. Due to the selective and parasitic nature of viral infection, it was expected that viral and host community dynamics would covary both in abundances and community composition. The temporal dynamics of the bacterial and cyanobacterial communities, as potential viral hosts, were studied in addition to a range of environmental parameters to relate these to viral community dynamics. Cyanobacterial and bacterial communities were studied applying epifluorescence microscopy, flow cytometry, and denaturing gradient gel electrophoresis (DGGE). Both bacterial and cyanobacterial communities followed a clear seasonal cycle. Contrary to expectations, viral abundances were neither correlated to abundances of the most dominant plankton groups in Lake Loosdrecht, the bacteria and the filamentous cyanobacteria, nor could we detect a correlation between the assemblage of viral and bacterial or cyanobacterial communities during the overall period. Only during short periods of strong fluctuations in microbial communities could we detect viral community assemblages to covary with cyanobacterial and bacterial communities. Methods with a higher specificity and resolution are probably needed to detect the more subtle virus–host interactions. Viral abundances did however relate to cyanobacterial community assemblage and showed a significant positive correlation to Chl-a as well as prochlorophytes, suggesting that a significant proportion of the viruses in Lake Loosdrecht may be phytoplankton and more specific cyanobacterial viruses. Temporal changes in bacterial abundances were significantly related to viral community assemblage, and vice versa, suggesting an interaction between viral and bacterial communities in Lake Loosdrecht

Inner-Outer Lane Advantage in Olympic 1000 Meter Speed Skating

During the Olympic Games and the World Championships Single Distances the 1000m is skated by every skater only one time. However, there may be a difference in skating a 1000m race with a start in the inner and the outer lane that introduces an externality that introduces unfairness. We show that this difference indeed exists. For the period 2000-2009 we observe a statistically significant advantage of starting in the inner lane of 0.120 seconds for women. For male skater the difference between starting lanes is 0.030, but not significantly different from zero. In order to make the competition fair, we suggest that the 1000m should be skated twice

Typical freshwater bacteria: an analysis of available 16S rRNA gene sequences from plankton of lakes and rivers

In order to identify patterns in bacterial community composition in freshwater habitats, we analyzed the available database of 16S rDNA sequences from freshwater plankton, including 24 new sequences from Parker River (Massachusetts, USA), 42 from Lake Soyang (South Korea) and 148 from Lake IJssel (The Netherlands). At this point, combined diversity studies using random cloning have deposited 689 bacterial and 75 plastid 16S rDNA sequences from the water column of rivers and lakes in North America, Europe and Asia. Systematic comparisons with the global database showed that the majority of the bacterial sequences were most closely related to other freshwater clones or isolates, while relatively few were closest to sequences recovered from soils or marine habitats. This habitat-specific clustering suggests that the clustered 16S rDNA sequences represent species or groups of species that are indigenous to freshwater. We have discerned 34 phylogenetic clusters of closely related sequences that are either restricted to freshwater or dominated by freshwater sequences. Of these clusters, 23 contained no cultivated organisms. These putative freshwater clusters were found among the alpha-, beta- and gamma-Proteobacteria, the Cytophaga-Flavobacterium-Bacteroides group, the Cyanobacteria, the Actinobacteria, the Verrucomicrobia, the green non-sulfur bacteria and candidate division OP10. This study shows that rivers and lakes have a specific planktonic bacterial community distinct from bacteria in neighboring environments such as soil and sediments. It also points out that these planktonic bacteria are distributed in diverse freshwater ecosystems around the world. [KEYWORDS: Microbial diversity · Ribosomal RNA gene · Freshwater · Habitat · Polymerase chain reaction · Phylogeny · Nucleotide sequence database

Typical freshwater bacteria: an analysis of available 16S rRNA gene sequences from plankton of lakes and rivers

In order to identify patterns in bacterial community composition in freshwater habitats, we analyzed the available database of 16S rDNA sequences from freshwater plankton, including 24 new sequences from Parker River (Massachusetts, USA), 42 from Lake Soyang (South Korea) and 148 from Lake IJssel (The Netherlands). At this point, combined diversity studies using random cloning have deposited 689 bacterial and 75 plastid 16S rDNA sequences from the water column of rivers and lakes in North America, Europe and Asia. Systematic comparisons with the global database showed that the majority of the bacterial sequences were most closely related to other freshwater clones or isolates, while relatively few were closest to sequences recovered from soils or marine habitats. This habitat-specific clustering suggests that the clustered 16S rDNA sequences represent species or groups of species that are indigenous to freshwater. We have discerned 34 phylogenetic clusters of closely related sequences that are either restricted to freshwater or dominated by freshwater sequences. Of these clusters, 23 contained no cultivated organisms. These putative freshwater clusters were found among the alpha-, beta- and gamma-Proteobacteria, the Cytophaga-Flavobacterium-Bacteroides group, the Cyanobacteria, the Actinobacteria, the Verrucomicrobia, the green non-sulfur bacteria and candidate division OP10. This study shows that rivers and lakes have a specific planktonic bacterial community distinct from bacteria in neighboring environments such as soil and sediments. It also points out that these planktonic bacteria are distributed in diverse freshwater ecosystems around the world. [KEYWORDS: Microbial diversity · Ribosomal RNA gene · Freshwater · Habitat · Polymerase chain reaction · Phylogeny · Nucleotide sequence database]