Research Techniques
The PDF files provided below give details on the techniques that have proven very reliable over many years in the field and laboratory. Also included are sources for supplies. Also shown below are some photographs to illustrate the techniques.
Making, staining, and storing blood smears.
See a movie of a smear being made
On the left below is shown three slides that have two smears made per slide. This is the method we use when traveling to field sites where large numbers of smears will be made. The slides shown in the picture on the left are fresh-made (not yet dipped into methanol). The top slide has one smear, the middle slide shows our practice when on field trips of putting two smears per slide, and the bottom slide is one typical for mammal blood with both a thick and thin smear.
The photo to the right shows some smears that have been stained with Giemsa. Three good slides are shown on the top. The ones staining pink are from gravid female lizards. Proteins used to produce egg yolk cycle through the blood and stain pink with Giemsa. The two lower slides show some poorly made smears. Note the “bubbles” on the left smear, second from the bottom. This is a result of grease on the slide.
Making and storing dried blood dots for genetic studies.
Storing dried blood from lizards or birds is easy and should be done with every animal sampled. The left photograph shows a filter paper disk with several blood samples, the right photo shows the disk in a small plastic zip-lock bag with some silica gel to keep the disk dry. These disks can be kept at room temperature until returning to the lab, then kept in the freezer at -20 C.
Scanning slides, identifying and counting parasites.
How to catch and take blood samples from birds and lizards.
Catching and taking blood samples from lizards is easy, and described in the pdf file. However, working with birds requires special training, and for wild birds, permits. Blood samples should be taken from birds only by veterinarians or wildlife workers who have received the necessary training. Use of mist-nets is also regulated, and even their purchase requires a permit. Although regulations vary among countries, researchers should still capture and take blood samples only after proper training, and should follow strict ethical guidelines. That is, presented the pictures below does not suggest that catching and handling birds should be done without the proper training.
A field station for identifying, sexing, measuring, banding, and taking blood samples for birds. The metal tray provides a clean, flat surface for making blood smears. Birds are kept in cloth sacks for the short period between being taken from a mist-net until processing. Birds typically become very quiet in a these sacks.
On the left, mist-nets are set in an area of forests where birds are seen to use as a fly-way. In the foreground, a goldfinch and redstart are seen in the net. Removing birds takes patience and skill because they can become very tangled in the net as seen for the goldfinch on the right.
A woodpecker is prepared to donate a blood sample by use of a moist Q-tip to push feathers away and reveal the brachal vein. A very thin syringe needle is used to prick the vein, and a capillary tube takes a blood sample. In the lower right phogograph a much smaller bird (a warbler) is giving a blood sample.
Noosing lizards can be very enjoyable, provided a properly made noose is used. We use tri-filament fishing line, but the pictures are shown here with heavy cord for illustration (such cord might be used to noose enormous Varanus lizards!). First, a knot is tied at the end of the line, then an overhand knot made. The long end of the string is pushed into the overhand knot, and then tightened. The picture on the lower left shows the finished noose. When a lizard is captured, it can be very quickly released by pulling on the “handle” of the noose (the knotted end).
Molecular methods: extracting DNA from dried blood dots, PCR, and sequencing
How to isolate microsatellite markers for malaria parasites
Calibration methods: Scoring clones of Plasmodium mexicanum