Knowledge Base

Check the DanioVision System

Before you start setting up EthoVision XT, you need to check the following:

• Camera: The camera lens should have the correct aperture and must be in focus. The camera must also be correctly configured.
• Anti-Condensation Mechanism: You need to do this depending on the temperature inside the DanioVision chamber and the desired water temperature around the well-plate.
• White Light Stimulus: You need to do this when you want to use very low intensities for the DanioVision White Light.
• Well Plates and Petri Dishes: The well plate or Petri dish must be inserted correctly. Always control evaporation in the basin and in the well plate, especially when you carry out long trials (greater than 1 day).

Check the Camera Lens

Although the camera and lens are set up before shipment, the settings of the lens can shift during transport. Before you start to work with the DanioVision system, please check that the lens is set up correctly by doing the following:

1. The lens you use depends on the video resolution and frame rate you want to use.
2. Insert a well plate or Petri dish in the basin.
3. Create a new EthoVision XT experiment and open the Arena Settings to see the camera image. When water is not present in the basin, the image of the well plate should look overexposed.
4. Check the focus. If the camera image is not in focus, loosen the screw, adjust the focus, and tighten the screw. The camera should be focused on the animals. The distance between animals and camera does not change much between types of well-plate and water level in the wells; however, it is always a good idea to check the image before an experiment and adjust the focus until it is optimized.
5. Check the aperture. The aperture has been adjusted so that when the basin is filled with water, the video image is optimal for tracking. In the Detection Settings, check that detection of the larvae is good. If necessary, adjust the aperture to get a better contrast between larvae and background.
6. Make sure the camera is correctly configured.

Note: The more the aperture is closed, the larger the depth of field, which means that an object is sharp at different distances from the lens. This is especially relevant when you work with a zoom lens and zoom in to focus on a smaller region of a well plate. On the other hand, closing the aperture decreases the contrast between animals and the background. Adjust the aperture until the image is optimized.

Configure the Anti-Condensation Mechanism

The DanioVision Observation Chamber is equipped with an anti-condensation mechanism to prevent water droplets forming on the lens during an experiment. A temperature sensor inside the DanioVision Observation Chamber checks whether the anti-condensation mechanism should be switched on or off when it is set to Auto mode. Besides Auto mode, you can also permanently switch the anti-condensation mechanism on or off. The switch to set the anti-condensation mode is located behind the camera, at the right side.

• Auto: Default and recommended when the DanioVision TCU is not used. The anti-condensation mechanism is automatically switched on when the air temperature inside the chamber drops below 28 °C (82.4 °F) to prevent condensation on the lens. When the air temperature inside the chamber exceeds 28 °C, the anti-condensation mechanism is automatically turned off to prevent heating of the water in the wells. The value of 28 °C is a default setting of the embedded controller.
• Off: The anti-condensation mechanism is permanently turned off. Use this mode when the air temperature inside the chamber is equal to or higher than the actual water temperature of the basin or well plate water (in most cases 28 °C). You can use this option in combination with the DanioVision TCU.
• On: The anti-condensation mechanism is permanently turned on. Use this mode when the air temperature inside the chamber is lower than the water temperature in the wells. You can use this option in combination with the DanioVision TCU.

Note: If you use the DanioVision TCU, follow the instructions in the Reference Manual - DanioVision Temperature Control Unit DV-TCU, and set the switch to either On or Off.

Configure the DanioVision White Light

In the DanioVision Observation Chamber it is possible to use very low light levels for the DanioVision White Light in addition to the default, standard white light levels. The standard light levels range from approximately 20 lux to approximately 10000 lux. The low light levels range from 0 to approximately 20 lux. Both standard and low light can be controlled in the same way by EthoVision XT's Trial and Hardware Control.

1. Locate the switch behind the camera, at the bottom-left of the black mini USB-IO Box.
2. Set the intensity of the White Light:
   • Right position (H): Standard high light level.
   • Left position (L): Low light level.

Place Well Plates and Petri Dishes

Well Plates (ANSI Standard)

1. Put the back of the well plate against the bridge and place it on the basin floor.
2. Tilt the front of the well plate down to the floor. This way the water in the basin pushes the air from underneath the well plate. Make sure the well plate is accommodated correctly between the metal springs at the front and at the right side.

Tip: Drill a few holes on the sides of the well plate to allow air to escape when placing the well plate.

Well Plates (Non-ANSI Standard)

For smaller or larger well plates, place the bridge in a different position. The default position (ANSI standard) corresponds to the second hole on the side walls of the basin, when counting from the inner side of the observation chamber.

1. Remove the screws as indicated in the picture.

Source: DanioVision DVOC-0041 Reference Manual, Noldus Information Technology