Cell Biology Group personnel:

Dr Natalia Yarovaya (Group Leader)

Dr Ludmilla Kramarova (Research Officer)

Judy Borg (Graduate Assistant)

Diane Stojanovski (Graduate Assistant)

Kally Vasilopoulos (Graduate Assistant)

Cell Biology Group:

The Cell Biology Group was only recently established at the Centre.  It has made significant progress in investigating the state of mitochondria in ageing skeletal muscle tissue.  Of great benefit to the Centre has been the acquisition of a Confocal Microscope, which allows the study of cells in fine detail.  With this state of the art instrument, both the structure and the activities of the components that make up the cell can be visualized.  Furthermore, unlike many other forms of microscopy, confocal analysis can be carried out on live cells allowing the study of the dynamic processes within them.  Due to the clarity of the computerized confocal microscope, it is possible to obtain information about, say, the overall state of mitochondria within a cell.  This is of key importance in investigations such as ours that are assessing possible local changes brought about by mitochondrial DNA mutation.

We have been using a number of tools in our investigations to ascertain the impact of ageing on the function of cells and tissues.  For instance, dyes such as nonyl-acridine orange that detects the mitochondrial structures, mitotracker red that measures the energy state of mitochondria, and antibodies to various sub-units of the respiratory chain may be used in the confocal microscope to study changes within mitochondria.  These tools allow us to study changes in the functional activity of the mitochondria in the cells and relate it to their structure.

The group has also been investigating the composition of the fiber types in our muscle samples.  Skeletal muscle is not homogeneous;  it consists of three different types of inter-mixed fibers, with different functions. Thus type I fibers are used for sustained activity and type IIa and IIb for concentrated bursts of activity such as sprinting.  We can distinguish these muscle types microscopically using fluorescently labeled antibodies.  As we know that the different fiber types have different modes of generating energy; it is important for us to investigate whether the different fiber types respond differently to ageing.  Our results to date suggest that the generalized loss of energy capacity applies to all fiber  types.

These studies are deepening our understanding of the bioenergy decline in aged muscle tissue and enabling us to develop diagnostics for the bioenergy state of tissues.  The examination of the effects of ageing on biological activities at the cellular and tissue level provides us with the opportunity to test and extend the observations made by the DNA, Bioenergy and Coenzyme Q10 groups at the Centre.

Confocal microscopy investigations of metabolic changes with age

The cell biology program has included the development of different procedures for the evaluation of bioenergy in muscle tissue using confocal laser scanning microscopy, which provides the capability for the microscope's high resolution images to be studied using sophisticated computer analysis.

For example, our confocal microscope embraces the study of human and rat skeletal muscle; muscles are complex structures made up of several intermixed fibre types that differ in their energy capacities. Using micro dissection techniques, single muscle fibres have been isolated and their energy capacities shown to be related to specific enzyme differences which also change with age. The confocal microscope studies of changes in ageing tissues are carried out interfacing with the microarray and other DNA studies.