total RNA extracted from DV, DA, AA and BM were subjected to northern blotting analysis. Similarly, to investigate whether transcription of DVHRF was developmentally regulated, total RNA of immature ticks (larvae and nymph) were also subjected to northern blotting analysis. Samples (3–7.5 lg total RNA per lane) treatment, electrophoresis and transfer to Hybond N + membranes were done as described in Northern-Max protocol (Ambion, Austin, TX). Following transfer, processing of the
RNA blots was done as previously described (Mulenga et al. 2003b). The
membranes were washed to a final stringency of 0.1· SSC plus 0.1 % SDS
at 65 C twice for 15 min each and subsequently exposed to an X-ray film
for 40 min at 80 C.