Li&Popadic 2004.pdf - Biological Sciences Home - Wayne State ...

316 EVOLUTION & DEVELOPMENT Vol. 6, No. 5, September^October 2004Fig. 3. The expression pattern of nub in cockroach Periplaneta americana embryos. (A–E) Early nub expression is localized specifically in theappendages and posterior abdomen, and only during late development does it extend into the mid-ventral region. (F–J) Highermagnification inserts of nub expression in the head appendages. (K–O) A series of magnified T2 leg inserts showing the dynamic nature ofnub expression during leg development. An, antenna; Mn, mandible; Mx maxilla; Lb, labium; T1–T3, thoracic legs; A3–A10, abdominalsegments. Leg segments: Cx, coxa; Tr, trochanter; Fe, femur; Ti, tibia; Ts, tarsus. Stars indicate the nonspecific staining in pleuropodia(appendages of the A1 segment).expression anteriorly. Two additional clusters of nub-expressingcells were observed in the trochanter, although at a verylow level. There was also novel nub expression in the tipof each leg.Embryonic expression patterns of nub in ahemipteran Oncopeltus fasciatusTo study hemipteran nub mRNA expression, we used thecloned Of Pdm cDNA fragment for whole-mount in situhybridization. Hemipterans represent one of the phylogenetically‘‘younger’’ hemimetabolous insect orders, comparedwith Zygentoma (firebrats) and Blattodea (cockroaches).Thus, studies of milkweed bug embryos provide an importantdata point, allowing us to infer whether the trends in nubexpression observed in more basal insect groups extend tohemipterans as well.Three key features characterized the nub expression inOncopeltus embryos (Fig. 4, A–E). First, during earlydevelopment, strong nub expression was localized primarily