New Bioimaging Method for Observing HPCs

August 13, 2009

timm_schroeder_hpcs

The research team led by Dr. Timm Schroeder, stem cell researcher at Helmholtz Center Munich, Germany has developed a new bioimaging method for observing the differentiation of hematopoietic progenitor cells (HPC) at the single-cell level. With this method the researchers were able to prove for the first time that not only cell-intrinsic mechanisms, but also external environmental factors such as growth factors can control HPC lineage choice directly. The findings, published in Science, provide an essential building block for understanding the molecular mechanisms of hematopoiesis and are an important prerequisite for optimizing therapeutic stem cell applications.

With the new bioimaging techniques developed by Dr. Schroeder’s team, progenitor cells could be observed for a longer period and on the single-cell level. Depending on the kind of cytokines present, after a few days the HPC cultures contained only one cell type. The question remained unanswered whether this was a consequence of direct cytokine regulation or merely the result of sorting out “erroneously differentiated” cells by cell death. Using the new bioimaging techniques for continuous single-cell observation, Dr. Michael Rieger and students in Dr. Schroeder’s research group showed for the first time that no cell death could be detected during the entire cell differentiation process. This proves unambiguously that HPC lineage choices can be steered by external environmental factors such as in this case by cytokines. The hematopoietic progenitor cells are “instructed” by cytokines.
www.helmholtz-muenchen.de

Original publication:
Rieger MA, Hoppe PS, Smejkal BM, Eitelhuber AC & Schroeder T (2009): Hematopoietic cytokines can instruct lineage choice. Science 325:217-218


Principles of Fluorescence Techniques

Juni 24, 2009

The Fluorescence Education Center, also referred to as the Fluorescence Foundation, will host two courses on the principles of fluorescence techniques to be held from:
June 29 – July 2, 2009 in Genova, Italy
and
September 14-17, 2009 in Madrid, Spain

The Principles of Fluorescence Techniques course will outline the basic concepts of fluorescence techniques and the successful utilization of the currently available commercial instrumentation. The course is designed for students who utilize fluorescence techniques and instrumentation and for researchers and industrial scientists who wish to deepen their knowledge of fluorescence applications. Key scientists in the field will deliver theoretical lectures. The lectures will be complemented by the direct utilization of steady state and lifetime fluorescence instrumentation and confocal microscopy for FLIM and FRET applications.

Topics addressed in this course include:

– Basic Definitions and Principles of Fluorescence
– Fluorescence Polarization
– Time-resolved Fluorescence
– Instrumentation
– Data Manipulation and Data Analysis
– Non-Linear Microscopy Including SHG
– GFP Fluorescence and Photoactivation
– Confocal and Multiphoton Fluorescence Microscopy
– FCS, Fluorescence Correlation Spectroscopy
– FLIM, Fluorescence Lifetime Imaging
– Single Molecule Imaging
– Image Processing and Deconvolution Approaches

www.fluorescence-foundation.org


New Technique to Receive Sharper Images

April 29, 2009

A new imaging method that could help to build more powerful microscopes and other optical devices by producing sharper images and a wider field of view has been developed by Princeton researches. The research was led by Jason Fleischer, assistant professor of electrical engineering and co-written with two graduate students Christopher Barsi and Wenjie Wan. The new method takes advantage of the unusual properties of nonlinear optical materials in which light rays mix with each other in complex ways. Thanks to the mixing of rays, information that would otherwise be lost manages to reach the detector. Therefore this picture would be rich in detail but it would also be distorted. To capture this otherwise lost visual information, the researchers used a hologram. The hologram is a special type of photograph which records „phase“ – a light property which measures the time and location of a wave peak. They also combined data from a normal camera. Then they created a simplified flow of light through a nonlinear material and developed a computer algorithm that takes the distorted image and works backwards to calculate the visual information at every point in space between the image and the object.
www.princeton.edu

An object illuminated by light reflects rays in many different directions (gray arrows). Left: With a normal lens, some rays are captured and refract towards a camera while others are missed, resulting in a blurry image with a limited field of view. Right: The new method uses a nonlinear material. The original rays are altered and new rays (red) are generated. The resulting picture is scrambled, but a computer algorithm can undo the mixing and yield a sharp, wide-field image.

An object illuminated by light reflects rays in many different directions (gray arrows). Left: With a normal lens, some rays are captured and refract towards a camera while others are missed, resulting in a blurry image with a limited field of view. Right: The new method uses a nonlinear material. The original rays are altered and new rays (red) are generated. The resulting picture is scrambled, but a computer algorithm can undo the mixing and yield a sharp, wide-field image. (Image: Christopher Barsi)


Light Microscopy Meets Structural Biology

April 21, 2009

A symposium with a focus on light microscopy and its application in structural biology, organized by the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany will take place form June 22-23, 2009. The symposium aims to bring together structural biologists, cell biologists and light microscopy specialists to explore opportunities and requirements for structural biologists in using different light microscopy techniques and to foster interactions at the interface between structural biology and cell biology.

Planned sessions include:
– Imaging protein-protein interactions
– Protein dynamics
– Correlative light- electron microscopy
– Super-resolution techniques

Deadline for registration is May 3, 2009.
www.embl.org

Heidelberg, Germany (source: pixelio.de)

Heidelberg, Germany (source: pixelio.de)


Distinguishing Single Cells With Nothing But Light

April 6, 2009

Researchers at the University of Rochester have developed a novel optical technique that permits rapid analysis of single human immune cells using only light. Andrew Berger, associate professor of optics and his graduate student Zachary Smith integrated Raman and angular-scattering microscopy into a single system, which they call IRAM. This is the first time clear differences between two types of immune cells have been seen using a microscopy system that gathers chemical and structural information by combining two previously distinct optical techniques, according to Berger. „Conceptually it’s pretty straightforward – you shine a specified wavelength of light onto your sample and you get back a large number of peaks spread out like a rainbow,“ says Berger. „The peaks tell you how the molecules you’re studying vibrate and together the vibrations give you the chemical information.“ Until now scientists have not had a non-invasive way to see how human cells, like T cells or cancer cells, activate individually and evolve over time.
www.rochester.edu

IRAM scattering data from a single granulocyte.

IRAM scattering data from a single granulocyte.

IRAM scattering data from a single lymphocyte. Clear differences are visible when compared to data from a granulocyte.

IRAM scattering data from a single lymphocyte. Clear differences are visible when compared to data from a granulocyte.