Project description:Complete metamorphosis of holometabolous insects is a complex biological process characterized by profound morphological, physiological, and transcriptional changes. To reveal the temporal dynamics of gene expression during this critical developmental transition, a detailed analysis of the developmental transcriptomes of two Drosophila species, Drosophila melanogaster and Drosophila virilis, was conducted. We confirm partial recapitulation of the embryonic transcriptional program in pupae, but instead of the traditional hourglass model, which posits maximal conservation at mid-embryonic stages, at different stages of pupae we observe a more complicated pattern of alternating low and high diversity, resembling an inverted hourglass, or "spindle". This observation challenges the notion of a singular conserved phylotypic period during holometabola ontogeny and underscores the complexity of developmental processes during complete metamorphosis. Notably, recently formed genes (specific to insects) exhibit pronounced expression peaks during mid-pupal development, underscoring their potential role in developmental transitions.
Project description:Background: We studied the chromatin accessibility landscsape in wings during butterfly metamorphosis, and investigate which transcription factors might be driving changes in accessibility Methods: We sequencing the Junonia coenia genome, and we studied chromatin accessibility using ATAC seq in multiple stages of wing development in both forewings and hindwings. For sites showing a large change in accessibility, we investigate which motifs are enriched, and correlate this with changes in gene expression of associated transcription factors. We confirm promising candidates with ChIP-seq Results: We find a highly dynamic landscape, with multiple peaks showing a double increase in accessibility throughout development. We show that transcription factor spineless, but not ecdysone receptor, is highly predictive of opening sites Conclusions: This work provides a characterization of the chromatin dynamics of insect wing metamorphosis, identifies novel candidate chromatin remodeling factors in insects, and provides the first genome assembly of the model butterfly Junonia coenia, with gene and cis-regulatory element annotations
Project description:Background: We studied the chromatin accessibility landscsape in wings during butterfly metamorphosis, and investigate which transcription factors might be driving changes in accessibility Methods: We sequencing the Junonia coenia genome, and we studied chromatin accessibility using ATAC seq in multiple stages of wing development in both forewings and hindwings. For sites showing a large change in accessibility, we investigate which motifs are enriched, and correlate this with changes in gene expression of associated transcription factors. We confirm promising candidates with ChIP-seq Results: We find a highly dynamic landscape, with multiple peaks showing a double increase in accessibility throughout development. We show that transcription factor spineless, but not ecdysone receptor, is highly predictive of opening sites Conclusions: This work provides a characterization of the chromatin dynamics of insect wing metamorphosis, identifies novel candidate chromatin remodeling factors in insects, and provides the first genome assembly of the model butterfly Junonia coenia, with gene and cis-regulatory element annotations
2019-04-30 | GSE121541 | GEO
Project description:RNA-seq of larval stages around molting and metamorphosis
Project description:In order to analyse gene expression during metamorphosis of Sycon ciliatum (Calcispongiae), we generated a series of RNA-Seq libraries representing subsequent stages of metamorphosis, ranging from freshly settled postlarvae (stage I) to functional ascon-grade juveniles (stage V).
Project description:According to previous studies, during Drosophila embryogenesis, RNA polymerase II is recruited to promoters at developmental stages preceding the stages of active transcription of genes. This work is aimed at exploring whether this mechanism is used during Drosophila metamorphosis. We performed ChIP-Seq analysis using antibodies to various modifications of RNA polymerase II (total, Pol II CTD Ser5P and Pol II CTD Ser2P), as well as to subunits of NELF, DSIF, PAF complexes and Brd4/Fs(1)h that control transcription elongation. We found that like in mid-embryogenesis during metamorphosis, promoters bind RNA polymerase II in the "paused" state preparing for activation at later stages of development. During mid-embryogenesis, RNA polymerase II in "pause" is phosphorylated at Ser5 and Ser2 of Rpb1 CTD and binds NELF, DSIF, and PAF complexes, but not Brd4/Fs(1)h. During metamorphosis, the "paused" RNA polymerase II complex includes Brd4/Fs(1)h in addition to NELF, DSIF, and PAF. The RNA polymerase II in this complex is phosphorylated at Ser5 at Rpb1 CTD, but not at Ser2.
Project description:Background: We studied the chromatin accessibility landscsape in wings during butterfly metamorphosis, and investigate which transcription factors might be driving changes in accessibility Methods: We sequencing the Junonia coenia genome, and we studied chromatin accessibility using ATAC seq in multiple stages of wing development in both forewings and hindwings. For sites showing a large change in accessibility, we investigate which motifs are enriched, and correlate this with changes in gene expression of associated transcription factors. We confirm promising candidates with ChIP-seq Results: We find a highly dynamic landscape, with multiple peaks showing a double increase in accessibility throughout development. We show that transcription factor spineless, but not ecdysone receptor, is highly predictive of opening sites Conclusions: This work provides a characterization of the chromatin dynamics of insect wing metamorphosis, identifies novel candidate chromatin remodeling factors in insects, and provides the first genome assembly of the model butterfly Junonia coenia, with gene and cis-regulatory element annotations
Project description:Is there a correlation between miRNA diversity and levels of organismic complexity? Exhibiting extraordinary levels of morphological and developmental complexity, insects are the most diverse animal class on earth. Their evolutionary success was in particular shaped by the innovation of holometabolan metamorphosis in endopterygotes. Previously, miRNA evolution had been linked to morphological complexity, but astonishing variation in the currently available miRNA complements of insects made this link unclear. To address this issue, we sequenced the miRNA complement of the hemimetabolan Blattella germanica and reannotated that of two other hemimetabolan species, Locusta migratoria and Acyrthosiphon pisum, and of four holometabolan species, Apis mellifera, Tribolium castaneum, Bombyx mori and Drosophila melanogaster. Our analyses show that the variation of insect miRNAs is an artefact mainly resulting from poor sampling and inaccurate miRNA annotation, and that insects share a conserved microRNA toolkit of 65 families exhibiting very low variation. For example, the evolutionary shift toward a complete metamorphosis was accompanied only by the acquisition of three and the loss of one miRNA families.
Project description:The success of neopteran insects, with 1 million species described, is associated with developmental innovations like the holometaboly and the evolution from short to long germ-band embryogenesis. To unveil the mechanisms underlining these innovations, we compared gene expression during the ontogeny of two extreme neopterans, the cockroach Blattella germanica (polyneopteran, hemimetabolan and short germ-band species), and the fly Drosophila melanogaster (endopterygote, holometabolan and long germ-band species). Results revealed that genes associated with metamorphosis are predominantly expressed in late nymphal stages in B. germanica and in early-mid embryo in D. melanogaster. In B. germanica the maternal to zygotic transition (MZT) concentrates early in embryogenesis, when juvenile hormone factors are significantly expressed. In D. melanogaster, the MZT extends throughout embryogenesis, during which juvenile hormone factors appear unimportant. These differences possibly reflect broad trends in the evolution of development within neopterans, related to the germ-band type and the metamorphosis mode.