Fig. 2. Expression and localisation of eve and h transcripts in five dipteran species at blastoderm stage. (A-J) eve and (K-T) h whole-mount in situ hybridisation showing transcript expression [(A-E,K-O) blue/purple (anterior towards the left, dorsal upwards)] and subcellular localisation [(F-J,P-T) red (apical is upwards and basal downwards in this and subsequent figures)]. Nuclear envelopes are shown in green pseudocolour (Alexa 660-wheat-germ agglutinin) in this and other figures. eve and h are found at high levels in the apical cytoplasm of Drosophila, Megaselia and Episyrphus, although in the latter species, localisation is less efficient. In Clogmia and Coboldia, these transcripts are distributed uniformly in the apicobasal axis. We identified two eve homologues in Clogmia, both of which are expressed in stripes and do not localise asymmetrically; Clogmia-eve2 is shown here. Arrowheads indicate the junction between the yolk and cytoplasm. In Coboldia and Clogmia, posteriormost stripes are established only after the onset of gastrulation (not shown). Unlike other dipteran h homologues Episyrphus-h is also expressed in the putative anlage of extra-embryonic tissue (not shown). Clogmia-h (O) is detected in a pair of anterior lateral patches and two stripes that might correspond to h stripes 1 and 6 in other species; expression in other stripe domains is weak or absent at blastoderm stages. Phylogenetic relationships of the species are shown below (Collins and Wiegmann, 2002; Yeates and Wiegmann, 1999). MYA, million years ago. Scale bar: 50 µm in F-J,P-T; 235 µm in A,K; 560 µm in B,J; 280 µm in C,M; 145 µm in D,N; 240 µm in E,O.