The Centrioles, Centrosomes, Basal Bodies, and Cilia of Drosophila melanogaster.

Centrioles play a key role in the development of the fly. They are needed for the correct formation of centrosomes, the organelles at the poles of the spindle that can persist as microtubule organizing centers (MTOCs) into interphase. The ability to nucleate cytoplasmic microtubules (MTs) is a property of the surrounding pericentriolar material (PCM). The centriole has a dual life, existing not only as the core of the centrosome but also as the basal body, the structure that templates the formation of cilia and flagellae. Thus the structure and functions of the centriole, the centrosome, and the basal body have an impact upon many aspects of development and physiology that can readily be modeled in Drosophila Centrosomes are essential to give organization to the rapidly increasing numbers of nuclei in the syncytial embryo and for the spatially precise execution of cell division in numerous tissues, particularly during male meiosis. Although mitotic cell cycles can take place in the absence of centrosomes, this is an error-prone process that opens up the fly to developmental defects and the potential of tumor formation. Here, we review the structure and functions of the centriole, the centrosome, and the basal body in different tissues and cultured cells of Drosophila melanogaster, highlighting their contributions to different aspects of development and cell division.Studies of centriole and basal body function in our laboratory are funded by the Wellcome Trust

Pharmaceutical analysis for environmental samples: Individual and simultaneous determination of ciprofloxacin, ofloxacin and norfloxacin using an HPLC with fluorescence and UV detection with a wetland soil matrix

Two HPLC methods were developed for individual and simultaneous determination of ciprofloxacin, norfloxacin and ofloxacin for use in laboratory experiments producing large numbers of samples (100 s to 1000 s). Individual compound detection produced retention times between 1.5 and 2 min and simultaneous detection between 6.5 to 8 min. The methods are compatible with complex geomatrices, e.g. a wetland soil. These methods provide 1) detection limits in the low parts per-billion range; 2) decrease in retention times of 5-10 times for single compounds, and up to 2 times for simultaneous detection over published methods; and 3) require no solid phase extraction. © Taylor & Francis Group, LLC

Competitive sorption and desorption behavior for three fluoroquinolone antibiotics in a wastewater treatment wetland soil

Significant amounts of pharmaceuticals are discharged into the environment through wastewater effluent. Sorption has been shown to be a significant aqueous removal pathway for many of these compounds. Competition between ciprofloxacin (CIP), ofloxacin (OFL) and norfloxacin (NOR) and their sorption to, and desorption from, a surrogate Louisiana wastewater treatment wetland soil were investigated to gain insight into the fate and transport of the pollutants within wastewater treatment wetlands. This study was undertaken in the context of a treatment wetland that continuously receives pharmaceuticals. Therefore it is important to understand the total capacity of this soil to sorb these compounds. Sorption to this treatment wetland soil was found to provide a major and potentially long-term removal pathway for these antibiotics from wastewater. LogKF values for all three compounds were between 4.09 and 3.90 for sorption and 4.24 and 4.05μg1-1/n(cm3)1/ng-1 for desorption. The compounds were sorbed in amounts ranging from 60% to 90% for high and low loading, respectively. The majority of the compounds were sorbed to the soil within the first 20h, indicating that treatment wetland may not need long retention times (weeks to months) in order to remove these compounds. Sorption KD values for competition (20ppm of each compound for 60ppm of total fluoroquinolones) ranged from 2300 to 3800cm3g-1 which is between both the 20 (4300-5800cm3g-1) and 60 (1300-3000cm3g-1) ppm single compound KD values, indicating that there is competition between these three compound for sorption sites. Sorption and desorption data (single component and mixture) collectively provide the following evidence: (1) NOR and, to a lesser extent, CIP outcompete OFL for sorption sites, (2) OFL sorbes to its share of quality sorption sites, and (3) competition only occurs for lesser quality binding sites. © 2010 Elsevier Ltd

Cytoplasmic Volume Modulates Spindle Size During Embryogenesis

Rapid and reductive cell divisions during embryogenesis require that intracellular structures adapt to a wide range of cell sizes. The mitotic spindle presents a central example of this flexibility, scaling with the dimensions of the cell to mediate accurate chromosome segregation. To determine whether spindle size regulation is achieved through a developmental program or is intrinsically specified by cell size or shape, we developed a system to encapsulate cytoplasm from Xenopus eggs and embryos inside cell-like compartments of defined sizes. Spindle size was observed to shrink with decreasing compartment size, similar to what occurs during early embryogenesis, and this scaling trend depended on compartment volume rather than shape. Thus, the amount of cytoplasmic material provides a mechanism for regulating the size of intracellular structures