Cytoplasmic streaming in onion cells

All cells are confined by a cell membrane, and in the case of plant cells this membrane is accompanied by a cell wall. Inside this envelope, each cell contains a lot of different organelles, molecules like proteins, carbohydrates and nutrients along with a cytoskeleton for structural support.

The organelles and macromolecules need to move around to get where they are needed. One way of achieving this is through passive diffusion. However, this process is very slow in the crowded cellular cytoplasm where up to 30% of the volume is taken up by macromolecules. To speed things up the cell utilizes a phenomenon called cytoplasmic streaming, also known as protoplasmic streaming and cyclosis. This kind of molecular movement, in contrast to diffusion, is not a passive but an active process which uses energy in the form of ATP (adenosine triphosphate). The energy is spent on moving specialized transport molecules called myosin, kinesin and dynein, along the cellular cytoskeleton while carrying the macromolecules and organelles.

Phase contrast - You always got a sample with you

Phase contrast is a widespread method in transmitted light microscopy. Especially in biology and medicine with their native samples this contrast method often is the easiest way to examine thin, unstained sections, smears and emulsions with almost no absorption.

The necessary hardware for Phase contrast 

• Figure 1: Objective with evaporated phase ring
• Figure 2: Illumination slot
• Figure 3: Centering telescope
• Figure 4: Phase ring

An objective with an evaporated Phase ring is combined with a respective illumination slot, placed in the focal plane of the condenser. The Centering telescope is a helpful tool to bring the round illumination ring to a perfect overlap with the partly transparent Phase ring. 

How to use the Phase Contrast accessories

Does this grow into a stink bug?

The Common green stinkbug or Palomena prasina is a common bug. You can find it in large parts of Europe, North Africa and the temperate parts of Asia. The bug has adapted to all kinds of biotopes such as forests, grasslands with suitable shrubs, marshes, gardens and parks, as long as food plants grow.

Allergic dermatitis in cats

When a cat comes into contact with an allergen, their body can react causing itching and inflammation. More severe cases of allergic dermatitis are easily recognized, while other may have very subtle signs and symptoms. That is why it is important to take a biopsy to make this sure and to investigate that it is not another ailment.