27 research outputs found
Expression of the Pupal Determinant broad during Metamorphic and Neotenic Development of the Strepsipteran Xenos vesparum Rossi
Derived members of the endoparasitic order Strepsiptera have acquired an extreme form of sexual dimorphism whereby males undergo metamorphosis and exist as free-living adults while females remain larviform, reaching sexual maturity within their hosts. Expression of the transcription factor, broad (br) has been shown to be required for pupal development in insects in which both sexes progress through metamorphosis. A surge of br expression appears in the last larval instar, as the epidermis begins pupal development. Here we ask if br is also up-regulated in the last larval instar of male Xenos vesparum Rossi (Stylopidae), and whether such expression is lost in neotenic larviform females. We clone three isoforms of br from X. vesparum (Xvâ˛br), and show that they share greatest similarity to the Z1, Z3 and Z4 isoforms of other insect species. By monitoring Xvâ˛br expression throughout development, we detect elevated levels of total br expression and the Xvâ˛Z1, Xvâ˛Z3, and Xvâ˛Z4 isoforms in the last larval instar of males, but not females. By focusing on Xvâ˛br expression in individual samples, we show that the levels of Xvâ˛BTB and Xvâ˛Z3 in the last larval instar of males are bimodal, with some males expressing 3X greater levels of Xvâ˛br than fourth instar femlaes. Taken together, these data suggest that neoteny (and endoparasitism) in females of Strepsiptera Stylopidia could be linked to the suppression of pupal determination. Our work identifies a difference in metamorphic gene expression that is associated with neoteny, and thus provides insights into the relationship between metamorphic and neotenic development. Š 2014 Erezyilmaz et al
A Novel Ecdysone Receptor Mediates Steroid-Regulated Developmental Events during the Mid-Third Instar of Drosophila
The larval salivary gland of Drosophila melanogaster synthesizes and secretes glue glycoproteins that cement developing animals to a solid surface during metamorphosis. The steroid hormone 20-hydroxyecdysone (20E) is an essential signaling molecule that modulates most of the physiological functions of the larval gland. At the end of larval development, it is known that 20Eâsignaling through a nuclear receptor heterodimer consisting of EcR and USPâinduces the early and late puffing cascade of the polytene chromosomes and causes the exocytosis of stored glue granules into the lumen of the gland. It has also been reported that an earlier pulse of hormone induces the temporally and spatially specific transcriptional activation of the glue genes; however, the receptor responsible for triggering this response has not been characterized. Here we show that the coordinated expression of the glue genes midway through the third instar is mediated by 20E acting to induce genes of the Broad Complex (BRC) through a receptor that is not an EcR/USP heterodimer. This result is novel because it demonstrates for the first time that at least some 20E-mediated, mid-larval, developmental responses are controlled by an uncharacterized receptor that does not contain an RXR-like component
Measurement of the energy asymmetry in t(t)over-barj production at 13 TeV with the ATLAS experiment and interpretation in the SMEFT framework
A measurement of the energy asymmetry in jet-associated top-quark pair production is presented using
139
fb
-
1
of data collected by the ATLAS detector at the Large Hadron Collider during pp collisions at
s
=
13
TeV
. The observable measures the different probability of top and antitop quarks to have the higher energy as a function of the jet scattering angle with respect to the beam axis. The energy asymmetry is measured in the semileptonic
t
t
ÂŻ
decay channel, and the hadronically decaying top quark must have transverse momentum above
350
GeV
. The results are corrected for detector effects to particle level in three bins of the scattering angle of the associated jet. The measurement agrees with the SM prediction at next-to-leading-order accuracy in quantum chromodynamics in all three bins. In the bin with the largest expected asymmetry, where the jet is emitted perpendicular to the beam, the energy asymmetry is measured to be
-
0.043
Âą
0.020
, in agreement with the SM prediction of
-
0.037
Âą
0.003
. Interpreting this result in the framework of the Standard Model effective field theory (SMEFT), it is shown that the energy asymmetry is sensitive to the top-quark chirality in four-quark operators and is therefore a valuable new observable in global SMEFT fits