Molecular individuality: polymorphism of salivary gland proteins in three species of ixodid tick.

Pooled tissue samples are frequently used in biochemical studies involving parasites in order to ensure that there is sufficient material for experimentation. A pooled sample is considered to represent the overall phenotypic characteristics of the investigated population. However, this will not be the case if there is a significant degree of molecular polymorphism among individuals in the sampled population. Here we demonstrate marked differences in the protein profile of salivary glands among individuals from three species of ixodid tick (Rhipicephalus appendiculatus, Amblyomma variegatum, Ixodes ricinus), and show that pooling the tissue of several individuals masks substantial qualitative differences among the individuals. Our observations indicate that much greater caution is needed in general when using pooled samples if the molecular diversity within the population is not clearly defined.