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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.
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