Highly restricted dispersal in habitat-forming seaweed may impede natural recovery of disturbed populations.

Cystoseira sensu lato (Class Phaeophyceae, Order Fucales, Family Sargassaceae) forests play a central role in marine Mediterranean ecosystems. Over the last decades, Cystoseira s.l.

Problems with the dating of sediment core using excess (210)Pb in a freshwater system impacted by large scale watershed changes.

Pb-210 dating of freshwater and coastal sediments have been extensively conducted over the past 40 years for historical pollution reconstruction studies, sediment focusing, sediment accumulation and mixing rate determination. In areas where there is large scale disturbance of sediments and the watershed, the vertical profiles of excess (210)Pb ((210)Pbxs) could provide erroneous or less reliable information on sediment accumulation rates. We analyzed one sediment core from Hendrix Lake in southwestern Arkansas for excess (210)Pb and (137)Cs.

Sizing subcellular organelles and nanoparticles confined within aqueous droplets.

This article describes two complementary techniques, single-particle tracking and correlation spectroscopy, for accurately sizing nanoparticles confined within picoliter volume aqueous droplets. Single-particle tracking works well with bright particles that can be continuously illuminated and imaged, and we demonstrated this approach for sizing single fluorescent beads. Fluorescence correlation spectroscopy detects small intensity bursts from particles or molecules diffusing through the confocal probe volume, which works well with dim and rapidly diffusing particles or molecules; we demonstrated FCS for sizing synaptic vesicles confined in aqueous droplets.

Continuous-flow single-molecule CE with high detection efficiency.

This paper describes the use of two-beam line-confocal detection geometry for measuring the total mobility of individual molecules undergoing continuous-flow CE separation. High-sensitivity single-molecule confocal detection is usually performed with a diffraction limited focal spot (approximately 500 nm in diameter), which necessitates the use of nanometer-sized channels to ensure all molecules flow through the detection volume. To allow for the use of larger channels that are a few micrometers in width, we employed cylindrical optics to define a rectangular illumination area that is diffraction-limited (approximately 500 nm) in width, but a few micrometers in length to match the width of the microchannel.

Accurate sizing of nanoparticles using confocal correlation spectroscopy.

The ability to accurately size low concentrations of nanoscale particles in small volumes is useful for a broad range of disciplines. Here, we characterize confocal correlation spectroscopy (CCS), which is capable of measuring the sizes of both fluorescent and nonfluorescent particles, such as quantum dots, gold colloids, latex spheres, and fluorescent beads. We accurately measured particles ranging in diameter from 11 to 300 nm, a size range that had been difficult to probe, owing to a phenomenon coined biased diffusion that causes diffusion times, or particle size, to deviate as a function of laser power.

Proton permeation into single vesicles occurs via a sequential two-step mechanism and is heterogeneous.

This article describes the first single-vesicle study of proton permeability across the lipid membrane of small (approximately 100 nm) uni- and multilamellar vesicles, which were composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). To follow proton permeation into the internal volume of each vesicle, we encapsulated carboxyfluorescein, a pH-sensitive dye whose fluorescence was quenched in the presence of excess protons. A microfluidic platform was used for easy exchange of high- and low-pH solutions, and fluorescence quenching of single vesicles was detected with single-molecule total internal reflection fluorescence (TIRF) microscopy.

Real-time sizing of nanoparticles in microfluidic channels using confocal correlation spectroscopy.

This Communication reports real-time sizing of nanoparticles in microfluidic systems using confocal correlation spectroscopy (CCS). CCS can be used to measure the size of both fluorescent and nonfluorescent particles at low concentrations ( View Article and Find Full Text PDF

High-power blue/UV light-emitting diodes as excitation sources for sensitive detection.

With advances in III-V nitride manufacturing processes, high-power light-emitting diode (LED) chips in the blue and UV wavelengths are now commercially available at reasonable cost and can be used as excitation sources in optical sensing. We describe the use of these high-power blue and UV LEDs for sensitive fluorescence detection, including chip-based flow cytometry, capillary electrophoresis (CE), and single-molecule imaging. By using a blue LED with a focusable power of approximately 40 mW as the excitation source for fluorescent beads, we demonstrate a simple chip-based bead sorter capable of enriching the concentration of green fluorescent beads from 63% to 95%.

Fast initiation of chemical reactions with laser-induced breakdown of a nanoscale partition.

This letter describes a new strategy for initiating a chemical reaction that is based on the laser-induced breakdown of a nanoscopic barrier, which physically separates the reactants in space. Because the breakdown of the barrier is fast ( approximately 0.3 micros) and owing to the nanometer dimension of the barrier, the reactants can be brought together and the reaction can be initiated rapidly.

Comparison between umbilical and transverse right upper abdominal incision for pyloromyotomy.

Background: Besides laparoscopic pyloromyotomy, the operation for pyloric stenosis has been performed using 2 standard open surgical exposures: the right upper quadrant (RUQ) incision and the semi-circumumbilical (UMB) incision. The aim of this study was to compare the morbidity and cosmetic results of both open exposures.

Methods: Between 1990 and 1995, we performed 104 pyloromyotomies through a RUQ incision.

Fabrication of thermoset polyester microfluidic devices and embossing masters using rapid prototyped polydimethylsiloxane molds.

Plastics are increasingly being used for the fabrication of Lab-on-a-Chip devices due to the variety of beneficial material properties, affordable cost, and straightforward fabrication methods available from a range of different types of plastics. Rapid prototyping of polydimethylsiloxane (PDMS) devices has become a well-known process for the quick and easy fabrication of microfluidic devices in the research laboratory; however, PDMS is not always an appropriate material for every application. This paper describes the fabrication of thermoset polyester microfluidic devices and masters for hot embossing using replica molding techniques.

Selective electroless and electrolytic deposition of metal for applications in microfluidics: fabrication of a microthermocouple.

This paper describes a general strategy for the fabrication of a microthermocouple based on the spatially defined electroless deposition of metal, followed by annealing and electroplating. We present scanning electron microscopy and atomic force microscopy characterizations of the deposition and annealing process, as well as the performance of the microfabricated Ni-Ag thermocouple. The temperature-voltage curve for this Ni-Ag microthermocouple is linear over the range 0-50 degrees C with a slope of 61.

Growth behavior of human pancreatic carcinoma xenograft correlates with nuclear features.

Two human pancreatic ductal adenocarcinomas with different growth rates were serially transplanted into nude mice. Feulgen-stained 4 microns sections and imprints from the xenografts were studied with a VICOM automated image analysis system. After pooling the results from two passages, with three mice in each passage, it was shown that of 23 nuclear parameters measured the following were correlated with a fast tumor growth rate: in sections, a decrease in heterogeneity of the chromatin and an increase in perimeter and nuclear area; in imprints, an increase in lesser diameter, in mean grey level difference between second neighboring pixels, and in total integrated optical density (DNA content).

Ultrastructural localization of a chondroitinase-sensitive, cuprolinic blue-positive filament in developing mouse lung.

By use of the cationic dye Cuprolinic Blue in a critical electrolyte concentration method, the lungs of mice ranging from the late fetal stage (17 days of gestation) to the puberal stage (27 days) were surveyed for their proteoglycans. A large Cuprolinic Blue-positive filament is present within the connective tissue of lungs of late fetal and young postnatal mice. It is mostly located at the boundary between large extracellular matrix structures and electron microscopically empty areas, but sometimes also at the surface of fibroblast-like cells.

Isolation and characterization of a collagen fibril-associated dermatan sulphate proteoglycan from bovine lung.

Dermatan sulphate proteoglycans have been extracted from bovine lung with 2.0 M CaCl2 and isolated using CsCl density gradient centrifugation, DEAE ion-exchange chromatography, gel chromatography and preparative sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Ultrastructurally these proteoglycans are specifically associated with collagen fibrils.

Ultrastructural localization of proteoglycans in tissue using cuprolinic blue according to the critical electrolyte concentration method: comparison with biochemical data from the literature.

Several connective tissues were stained for proteoglycans using the cationic dye Cuprolinic Blue according to the critical electrolyte concentration method. With this method, proteoglycans are visualized as electron-dense filaments. In most tissues, two types of proteoglycan filaments are present: a small (maximum length 60 nm), thin, collagen fibril-associated filament, and a thick, heavily-staining filament which is predominantly localized between bundles of collagen fibrils.

Further characterization of a large proteoglycan in human lung alveoli.

By use of the cationic dye Cuprolinic Blue in a critical electrolyte concentration method, heavily staining, generally large, filaments have been demonstrated in human lung alveoli. In some lung specimens they are abundant, while in others they are very scanty. The filaments are seen: around bundles of collagen fibrils, at places which seem electron microscopically almost empty, associated with basement membranes around elastin, and sometimes associated with individual collagen fibrils.

Ultrastructural localization and characterization of proteoglycans in human lung alveoli.

In order to localize and characterize proteoglycans in human lung alveoli, we have used the cationic dye Cuprolinic Blue according to the critical electrolyte concentration method. After staining, five types of Cuprolinic Blue-positive filaments become apparent: two types in the basement membranes of type I and type II epithelial cells respectively and lying in one or two layers; one type, more scattered, localized in the basement membrane of the endothelial cells and another kind associated with collagen fibrils and separated from each other according to the main banding period (+/- 60 nm) of these fibrils. Finally, there was a type of filament which was only locally present at a variety of places.

Staining of proteoglycans in mouse lung alveoli. II. Characterization of the Cuprolinic blue-positive, anionic sites.

The nature of Cuprolinic Blue-positive anionic filaments in mouse lung alveoli has been characterized. The contrast of filaments in the alveolar basement membrane of type I epithelial cells was lost on treatment with nitrous acid and pronase (without prefixation). In contrast, neither neuraminidase, chondroitinase ABC or AC, nor Streptomyces hyaluronidase had any effect.

Staining of proteoglycans in mouse lung alveoli. I. Ultrastructural localization of anionic sites.

In order to contrast anionic sites in mouse lung alveoli, two staining procedures were applied: (a) staining with Ruthenium Red and Alcian Blue and (b) staining with Cuprolinic Blue in a critical electrolyte concentration method. The Ruthenium Red-Alcian Blue staining procedure revealed electron-dense granules in the alveolar basement membrane. The granules were closely associated with the epithelial cell membrane and continued to stain even when the procedure was carried out at a low pH, indicating the presence of sulphate groups in the granules.

Substrate specificity and mode of action of the zinc-metallo nuclease from Physarum polycephalum.

The alkaline zinc-metallo nuclease of Physarum polycephalum is an endonuclease with a high specificity for single-stranded nucleic acids. Single-stranded DNA was cleaved at least 6,000 times faster than double-stranded DNA under identical conditions. In the supercoil-induced single-stranded region of Form I PM2 DNA only a single nick was made.

Nucleic acids and related enzymes. Secretion of four alkaline DNases by plasmodia of Physarum polycephalum.

In plasmodia of Physarum polycephalum, DNase activity with a preference for native DNA was found in a pattern of three or four isoenzymes. During growth a constant specific activity of approx. 0.