Photosynthetic Activity in Marine and Brackish Water Strains of Fucus vesiculosus and Fucus radicans (Phaeophyceae) at Different Light Qualities

This study investigates the effects of different light qualities on the photosynthetic capacity of the brown algae Fucus vesiculosus, from the Norwegian Sea, and Fucus radicans and F. vesiculosus, from the Bothnian Sea. The electron transport rates (ETR) obtained for F. vesiculosus from the Norwegian Sea showed significantly higher levels of light saturation compared with both species of algae from the Bothnian Sea. The maximum of ETR values for the Norwegian Sea strain showed no significant changes due to varying light quality compared with the initial values. For F. vesiculosus, from the Bothnian Sea, treatment with blue light showed an effect after 1 week of 30 and 90 μmol photons m^?2 s^?1 (P < 0.01), and for F. radicans from the Bothnian Sea, at the irradiance of 90 μmol photons m^?2 s^?1 and 1 week (P < 0.01). After 1 week in the Bothnian Sea species and after 2 weeks in F. vesiculosus from the Norwegian Sea, the photosynthetic efficiency (α) was significantly higher regardless of light quality and irradiance compared with the initial values. Variation in light quality and irradiance had minor effects on the F_v:F_m values of the three algal strains studied.     

Towards high-throughput single cell/clone cultivation and analysis

In order to better understand cellular processes and behavior, a controlled way of studying high numbers of single cells and their clone formation is greatly needed. Numerous ways of ordering single cells into arrays have previously been described, but platforms in which each cell/clone can be addressed to an exact position in the microplate, cultivated for weeks and treated separately in a high-throughput manner have until now been missing. Here, a novel microplate developed for high-throughput single cell/clone cultivation and analysis is presented. Rapid single cell seeding into microwells, using conventional flow cytometry, allows several thousands of single cells to be cultivated, short-term (72 h) or long-term (10-14 days), and analyzed individually. By controlled sorting of individual cells to predefined locations in the microplate, analysis of single cell heterogeneity and clonogenic properties related to drug sensitivity can be accomplished. Additionally, the platform requires remarkably low number of cells, a major advantage when screening limited amounts of patient cell samples. By seeding single cells into the microplate it is possible to analyze the cells for over 14 generations, ending up with more than 10 000 cells in each well. Described here is a proof-of-concept on compartmentalization and cultivation of thousands of individual cells enabling heterogeneity analysis of various cells/clones and their response to different drugs.     

Geometric phase-shifting for low-coherence interference microscopy

A low-coherence Linnik interference microscope using high numerical aperture optics has been constructed. The system uses a tungsten halogen lamp and Köhler illumination, with separate control over field and aperture stops, so that experiments can be conducted with a range of different operating conditions. The novel feature of the system is the use of an achromatic phase-shifter operating on the principle of the geometric phase, achieved by using a polarising beam splitter, a quarter wave plate and a rotating polariser. Image information is extracted from the visibility of the fringes, the position of the visibility peak along the scanning axis yielding the height of the test surface at the corresponding point.     

Detection and Analysis of Low‐Abundance Cell‐Surface Biomarkers Using Enzymatic Amplification in Microfluidic Droplets

Finding the few : Cell‐surface proteins are useful disease biomarkers, but current high‐throughput methods are limited to detecting cells expressing more than several hundred proteins. Enzymatic amplification in microfluidic droplets (see picture) is a high‐throughput method for detection and analysis of cell‐surface biomarkers expressed at very low levels on individual human cells. Droplet optical labels allow concurrent analysis of several samples.

     

Droplet Microfluidics—A Tool for Single‐Cell Analysis

Droplet microfluidics allows the isolation of single cells and reagents in monodisperse picoliter liquid capsules and manipulations at a throughput of thousands of droplets per second. These qualities allow many of the challenges in single‐cell analysis to be overcome. Monodispersity enables quantitative control of solute concentrations, while encapsulation in droplets provides an isolated compartment for the single cell and its immediate environment. The high throughput allows the processing and analysis of the tens of thousands to millions of cells that must be analyzed to accurately describe a heterogeneous cell population so as to find rare cell types or access sufficient biological space to find hits in a directed evolution experiment. The low volumes of the droplets make very large screens economically viable. This Review gives an overview of the current state of single‐cell analysis involving droplet microfluidics and offers examples where droplet microfluidics can further biological understanding.     

Internal conversion studies of transitions in96Mo

The internal conversion spectrum from the decay of⁹⁶Tc has been investigated using a 50 cm radius double-focussing beta-ray spectrometer. Relevant features of the internal conversion spectrum from the decay of⁹⁶Nb have also been reexamined in the same way. Special interest has been focussed on investigating a proposed doublet level structure at about 2.44 MeV and higher lying levels in⁹⁶Mo. Internal conversion coefficients have been obtained for most transitions by combining the measured conversion electron intensities obtained in this work with recently reported gamma-ray intensities from Ge(Li) detector measurements. A level scheme has been compiled and deduced transition multipolarities have been used for a discussion of spins and parities for the levels.     

Droplet size based separation by deterministic lateral displacement-separating droplets by cell--induced shrinking

We present a novel method for passive separation of microfluidic droplets by size at high throughput using deterministic lateral displacement (DLD). We also show that droplets containing Saccharomyces cerevisiae shrink significantly during incubation while droplets containing only yeast media retain or slightly increase their size. We demonstrate the DLD device by sorting out shrunken yeast-cell containing droplets from 31% larger diameter droplets which were generated at the same time containing only media, present at a >40-fold excess. This demonstrates the resolving power of droplet separation by DLD and establishes that droplets can be separated for a biological property of the droplet contents discriminated by a change of the physical properties of the droplet. Thus suggesting that this technique may be used for e.g. clonal selection. The same device also separates 11 μm from 30 μm droplets at a rate of 12,000 droplets per second, more than twofold faster than previously demonstrated passive hydrodynamic separation devices.