Abstract
Hairy
stripes in
Tribolium
are generated during blastoderm and germ band extension, but a direct role for
Tc
-
h
in trunk segmentation was not found. We have studied here several aspects of
hairy
function and expression in
Tribolium
, to further elucidate its role. First, we show that there is no functional redundancy with other
hairy
paralogues in
Tribolium
. Second, we cloned the
hairy
orthologue from
Tribolium confusum
and show that its expression mimics that of
Tribolium castaneum
, implying that stripe expression should be functional in some way. Third, we show that the dynamics of stripe formation in the growth zone is not compatible with an oscillatory mechanism comparable to the one driving the expression of
hairy
homologues in vertebrates. Fourth, we use parental RNAi experiments to study
Tc
-
h
function and we find that mandible and labium are particularly sensitive to loss of
Tc
-
h
, reminiscent of a pair-rule function in the head region. In addition, lack of
Tc
-
h
leads to cell death in the gnathal region at later embryonic stages, resulting in a detachment of the head. Cell death patterns are also altered in the midline. Finally, we have analysed the effect of
Tc-h
knockdown on two of the target genes of
hairy
in
Drosophila
, namely
fushi tarazu
and
paired
. We find that the trunk expression of
Tc-h
is required to regulate
Tc-ftz
, although
Tc-ftz
is itself also not required for trunk segmentation in
Tribolium
. Our results imply that there is considerable divergence in
hairy
function between
Tribolium
and
Drosophila
.