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Carolina G Santos - One of the best experts on this subject based on the ideXlab platform.

  • the mekre93 methoprene tolerant kruppel homolog 1 e93 pathway in the regulation of insect metamorphosis and the homology of the pupal stage
    Insect Biochemistry and Molecular Biology, 2014
    Co-Authors: Carolina G Santos
    Abstract:

    Recent studies on transcription factor E93 revealed that it triggers adult morphogenesis in Blattella germanica, Tribolium castaneum and Drosophila melanogaster. Moreover, we show here that Kruppel homolog 1 (Kr-h1), a transducer of the antimetamorphic action of juvenile hormone (JH), represses E93 expression. Kr-h1 is upstream of E93, and upstream of Kr-h1 is Methoprene-tolerant (Met), the latter being the JH receptor in hemimetabolan and Holometabolan species. As such, the Met – Kr-h1 – E93 pathway (hereinafter named “MEKRE93 pathway”) appears to be central to the status quo action of JH, which switch adult morphogenesis off and on in species ranging from cockroaches to flies. The decrease in Kr-h1 mRNA and the rise of E93 expression that triggers adult morphogenesis occur at the beginning of the last instar nymph or in the prepupae of hemimetabolan and Holometabolan species, respectively. This suggests that the hemimetabolan last nymph (considering the entire stage, from the apolysis to the last instar until the next apolysis that gives rise to the adult) is ontogenetically homologous to the Holometabolan pupa (also considered between two apolyses, thus comprising the prepupal stage).

Bellés Xavier - One of the best experts on this subject based on the ideXlab platform.

  • Krüppel homolog 1 and E93: The doorkeeper and the key to insect metamorphosis
    'Wiley', 2020
    Co-Authors: Bellés Xavier
    Abstract:

    Insect metamorphosis is regulated by two main hormones: ecdysone (20E), which promotes molting, and juvenile hormone (JH), which inhibits adult morphogenesis. The transduction mechanisms for the respective hormonal signals include the transcription factors Krüppel homolog 1 (Kr-h1) and E93, which are JH- and 20E-dependent, respectively. Kr-h1 is the main effector of the antimetamorphic action of JH, while E93 is a key promoter of metamorphosis. The ancestral regulatory axis of metamorphosis, which operates in insects with hemimetabolan (gradual) metamorphosis and is known as the MEKRE93 pathway, is based on Kr-h1 repression of E93. In the last juvenile stage, when the production of JH dramatically decreases, Kr-h1 expression is almost completely interrupted, E93 becomes upregulated and metamorphosis proceeds. The Holometabolan (complete) metamorphosis mode of development includes the peculiar pupal stage, a sort of intermediate between the final larval instar and the adult stage. In Holometabolan species, Broad-Complex (BR-C) transcription factors determine the pupal stage and E93 stimulates the expression of BR-C in the prepupa. The MEKRE93 pathway is conserved in Holometabolan insects, which have added the E93/BR-C interaction loop to the ancestral (hemimetabolan) pathway during the evolution from hemimetaboly to holometaboly.Work supported by Spanish Ministry of Economy and Competitiveness Grants CGL2012–36251 and CGL2015–64727‐P, by Catalan Government Grant 2017 SGR 1030, and by the European Fund for Economic and Regional Development (FEDER funds)

  • The innovation of the final moult and the origin of insect metamorphosis
    'The Royal Society', 2020
    Co-Authors: Bellés Xavier
    Abstract:

    The three modes of insect postembryonic development are ametaboly, hemimetaboly and holometaboly, the latter being considered the only significant metamorphosis mode. However, the emergence of hemimetaboly, with the genuine innovation of the final moult, represents the origin of insect metamorphosis and a necessary step in the evolution of holometaboly. Hemimetaboly derives from ametaboly and might have appeared as a consequence of wing emergence in Pterygota, in the early Devonian. In extant insects, the final moult is mainly achieved through the degeneration of the prothoracic gland (PG), after the formation of the winged and reproductively competent adult stage. Metamorphosis, including the formation of the mature wings and the degeneration of the PG, is regulated by the MEKRE93 pathway, through which juvenile hormone precludes the adult morphogenesis by repressing the expression of transcription factor E93, which triggers this change. The MEKRE93 pathway appears conserved in extant metamorphosing insects, which suggest that this pathway was operative in the Pterygota last common ancestor. We propose that the final moult, and the consequent hemimetabolan metamorphosis, is a monophyletic innovation and that the role of E93 as a promoter of wing formation and the degeneration of the PG was mechanistically crucial for their emergence. This article is part of the theme issue 'The evolution of complete metamorphosis'.This work was supported by the Spanish Ministry of Economy and Competitiveness (grant nos. CGL2012–36251 and CGL2015–64727-P) and the Catalan Government (grant 2017 SGR 1030). It also received financial assistance from the European Fund for Economic and Regional Development (FEDER funds)

  • Comparative Transcriptomics in Two Extreme Neopterans Reveals General Trends in the Evolution of Modern Insects
    'Elsevier BV', 2018
    Co-Authors: Ylla Guillem, Piulachs Maria-dolors, Bellés Xavier
    Abstract:

    The success of neopteran insects, with 1 million species described, is associated with developmental innovations such as holometaboly and the evolution from short to long germband 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 germband species) and the fly Drosophila melanogaster (endopterygote, Holometabolan, and long germband species). Results revealed that genes associated with metamorphosis are predominantly expressed in late nymphal stages in B. germanica and in the 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 time juvenile hormone factors appear to be unimportant. These differences possibly reflect broad trends in the evolution of development within neopterans, related to the germband type and the metamorphosis mode.This work was supported by the Spanish Ministry of Economy and Competitiveness (grants CGL2012-36251 and CGL2015-64727-P to X.B., including FEDER funds), Spanish Ministry of Science and Innovation (grants BFU2011–22404 and CGL2016–76011-R to M.-D.P., including FEDER funds), and Catalan Government (grants 2014 SGR 619 and 2017 SGR 1030).Peer reviewe

  • Comparative analysis of miRNA expression during the development of insects of different metamorphosis modes and germ-band types
    'Springer Science and Business Media LLC', 2018
    Co-Authors: Ylla Guillem, Piulachs Maria-dolors, Bellés Xavier
    Abstract:

    [Background]: Do miRNAs contribute to specify the germ-band type and the body structure in the insect embryo? Our goal was to address that issue by studying the changes in miRNA expression along the ontogeny of the German cockroach Blattella germanica, which is a short germ-band and hemimetabolan species. [Results]: We sequenced small RNA libraries representing 11 developmental stages of B. germanica ontogeny (with especial emphasis on embryogenesis) and the changes in miRNA expression were examined. Data were compared with equivalent data for two long germ-band Holometabolan species Drosophila melanogaster and Drosophila virilis, and the short germ-band Holometabolan species Tribolium castaneum. The identification of B. germanica embryo small RNA sequences unveiled miRNAs not detected in previous studies, such as those of the MIR-309 family and 54 novel miRNAs. Four main waves of miRNA expression were recognized (with most miRNA changes occurring during the embryonic stages): the first from day 0 to day 1 of embryogenesis, the second during mid-embryogenesis (days 0-6), the third (with an acute expression peak) on day 2 of embryonic development, and the fourth during post-embryonic development. The second wave defined the boundaries of maternal-to-zygotic transition, with maternal mRNAs being cleared, presumably by Mir-309 and associated scavenger miRNAs. [Conclusion]: miRNAs follow well-defined patterns of expression over hemimetabolan ontogeny, patterns that are more diverse during embryonic development than during the nymphal stages. The results suggest that miRNAs play important roles in the developmental transitions between the embryonic stages of development (starting with maternal loading), during which they might influence the germ-band type and metamorphosis mode.This work was supported by the Spanish Ministry of Economy and Competitiveness (grants CGL2012–36251 and CGL2015–64727-P to X.B.), the Spanish Ministry of Science and Innovation (grants BFU2011–22404 and CGL2016–76011-R to M.D.P.) and the Catalan Government (2014 SGR 619). It also received financial assistance from the European Fund for Economic and Regional Development (FEDER funds to X.B. and M.D.P.).We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).Peer Reviewe

  • The MEKRE93 (Methoprene tolerant-Krüppel homolog 1-E93) pathway in the regulation of insect metamorphosis, and the homology of the pupal stage
    'Elsevier BV', 2015
    Co-Authors: Bellés Xavier, Santos, Carolina G.
    Abstract:

    Recent studies on transcription factor E93 revealed that it triggers adult morphogenesis in Blattella germanica, Tribolium castaneum and Drosophila melanogaster. Moreover, we show here that Krüppel homolog 1 (Kr-h1), a transducer of the antimetamorphic action of juvenile hormone (JH), represses E93 expression. Kr-h1 is upstream of E93, and upstream of Kr-h1 is Methoprene-tolerant (Met), the latter being the JH receptor in hemimetabolan and Holometabolan species. As such, the Met - Kr-h1 - E93 pathway (hereinafter named >MEKRE93 pathway>) appears to be central to the status quo action of JH, which switch adult morphogenesis off and on in species ranging from cockroaches to flies. The decrease in Kr-h1 mRNA and the rise of E93 expression that triggers adult morphogenesis occur at the beginning of the last instar nymph or in the prepupae of hemimetabolan and Holometabolan species, respectively. This suggests that the hemimetabolan last nymph (considering the entire stage, from the apolysis to the last instar until the next apolysis that gives rise to the adult) is ontogenetically homologous to the Holometabolan pupa (also considered between two apolyses, thus comprising the prepupal stage). © 2014 Elsevier Ltd.Support for the original research included in this work was provided by the Spanish MICINN (grant CGL2008-03517/BOS to XB) and MINECO (grant CGL2012-36251 to XB) and by the CSIC (grant 2010TW0019, from the Formosa program, to XB). CGS received a Grant from Brazil Government (Processo CNPQ, 24574812012-L) to work in the Institute of Evolutionary Biology in Barcelona.Peer Reviewe

Bernhard Misof - One of the best experts on this subject based on the ideXlab platform.

  • An integrative phylogenomic approach to elucidate the evolutionary history and divergence times of Neuropterida (Insecta: Holometabola).
    BMC evolutionary biology, 2020
    Co-Authors: Alexandros Vasilikopoulos, Karen Meusemann, Bernhard Misof, Rolf G. Beutel, Doria Lieberz, Tomas Flouri, Oliver Niehuis, Torsten Wappler, Jes Rust, Ralph S. Peters
    Abstract:

    The latest advancements in DNA sequencing technologies have facilitated the resolution of the phylogeny of insects, yet parts of the tree of Holometabola remain unresolved. The phylogeny of Neuropterida has been extensively studied, but no strong consensus exists concerning the phylogenetic relationships within the order Neuroptera. Here, we assembled a novel transcriptomic dataset to address previously unresolved issues in the phylogeny of Neuropterida and to infer divergence times within the group. We tested the robustness of our phylogenetic estimates by comparing summary coalescent and concatenation-based phylogenetic approaches and by employing different quartet-based measures of phylogenomic incongruence, combined with data permutations. Our results suggest that the order Raphidioptera is sister to Neuroptera + Megaloptera. Coniopterygidae is inferred as sister to all remaining neuropteran families suggesting that larval cryptonephry could be a ground plan feature of Neuroptera. A clade that includes Nevrorthidae, Osmylidae, and Sisyridae (i.e. Osmyloidea) is inferred as sister to all other Neuroptera except Coniopterygidae, and Dilaridae is placed as sister to all remaining neuropteran families. Ithonidae is inferred as the sister group of monophyletic Myrmeleontiformia. The phylogenetic affinities of Chrysopidae and Hemerobiidae were dependent on the data type analyzed, and quartet-based analyses showed only weak support for the placement of Hemerobiidae as sister to Ithonidae + Myrmeleontiformia. Our molecular dating analyses suggest that most families of Neuropterida started to diversify in the Jurassic and our ancestral character state reconstructions suggest a primarily terrestrial environment of the larvae of Neuropterida and Neuroptera. Our extensive phylogenomic analyses consolidate several key aspects in the backbone phylogeny of Neuropterida, such as the basal placement of Coniopterygidae within Neuroptera and the monophyly of Osmyloidea. Furthermore, they provide new insights into the timing of diversification of Neuropterida. Despite the vast amount of analyzed molecular data, we found that certain nodes in the tree of Neuroptera are not robustly resolved. Therefore, we emphasize the importance of integrating the results of morphological analyses with those of sequence-based phylogenomics. We also suggest that comparative analyses of genomic meta-characters should be incorporated into future phylogenomic studies of Neuropterida.

  • An integrative phylogenomic approach to elucidate the evolutionary history and divergence times of Neuropterida (Insecta: Holometabola)
    'Springer Science and Business Media LLC', 2020
    Co-Authors: Alexandros Vasilikopoulos, Karen Meusemann, Bernhard Misof, Rolf G. Beutel, Doria Lieberz, Tomas Flouri, Oliver Niehuis, Torsten Wappler, Jes Rust, Ralph S. Peters
    Abstract:

    Abstract Background The latest advancements in DNA sequencing technologies have facilitated the resolution of the phylogeny of insects, yet parts of the tree of Holometabola remain unresolved. The phylogeny of Neuropterida has been extensively studied, but no strong consensus exists concerning the phylogenetic relationships within the order Neuroptera. Here, we assembled a novel transcriptomic dataset to address previously unresolved issues in the phylogeny of Neuropterida and to infer divergence times within the group. We tested the robustness of our phylogenetic estimates by comparing summary coalescent and concatenation-based phylogenetic approaches and by employing different quartet-based measures of phylogenomic incongruence, combined with data permutations. Results Our results suggest that the order Raphidioptera is sister to Neuroptera + Megaloptera. Coniopterygidae is inferred as sister to all remaining neuropteran families suggesting that larval cryptonephry could be a ground plan feature of Neuroptera. A clade that includes Nevrorthidae, Osmylidae, and Sisyridae (i.e. Osmyloidea) is inferred as sister to all other Neuroptera except Coniopterygidae, and Dilaridae is placed as sister to all remaining neuropteran families. Ithonidae is inferred as the sister group of monophyletic Myrmeleontiformia. The phylogenetic affinities of Chrysopidae and Hemerobiidae were dependent on the data type analyzed, and quartet-based analyses showed only weak support for the placement of Hemerobiidae as sister to Ithonidae + Myrmeleontiformia. Our molecular dating analyses suggest that most families of Neuropterida started to diversify in the Jurassic and our ancestral character state reconstructions suggest a primarily terrestrial environment of the larvae of Neuropterida and Neuroptera. Conclusion Our extensive phylogenomic analyses consolidate several key aspects in the backbone phylogeny of Neuropterida, such as the basal placement of Coniopterygidae within Neuroptera and the monophyly of Osmyloidea. Furthermore, they provide new insights into the timing of diversification of Neuropterida. Despite the vast amount of analyzed molecular data, we found that certain nodes in the tree of Neuroptera are not robustly resolved. Therefore, we emphasize the importance of integrating the results of morphological analyses with those of sequence-based phylogenomics. We also suggest that comparative analyses of genomic meta-characters should be incorporated into future phylogenomic studies of Neuropterida

  • Signatures of DNA Methylation across Insects Suggest Reduced DNA Methylation Levels in Holometabola.
    Genome biology and evolution, 2018
    Co-Authors: Panagiotis Provataris, Karen Meusemann, Oliver Niehuis, Sonja Grath, Bernhard Misof
    Abstract:

    It has been experimentally shown that DNA methylation is involved in the regulation of gene expression and the silencing of transposable element activity in eukaryotes. The variable levels of DNA methylation among different insect species indicate an evolutionarily flexible role of DNA methylation in insects, which due to a lack of comparative data is not yet well-substantiated. Here, we use computational methods to trace signatures of DNA methylation across insects by analyzing transcriptomic and genomic sequence data from all currently recognized insect orders. We conclude that: 1) a functional methylation system relying exclusively on DNA methyltransferase 1 is widespread across insects. 2) DNA methylation has potentially been lost or extremely reduced in species belonging to springtails (Collembola), flies and relatives (Diptera), and twisted-winged parasites (Strepsiptera). 3) Holometabolous insects display signs of reduced DNA methylation levels in protein-coding sequences compared with hemimetabolous insects. 4) Evolutionarily conserved insect genes associated with housekeeping functions tend to display signs of heavier DNA methylation in comparison to the genomic/transcriptomic background. With this comparative study, we provide the much needed basis for experimental and detailed comparative analyses required to gain a deeper understanding on the evolution and function of DNA methylation in insects.

  • Insect phylogenomics: results, problems and the impact of matrix composition
    Proceedings of The Royal Society B: Biological Sciences, 2012
    Co-Authors: Harald Letsch, Karen Meusemann, Rolf Georg Beutel, Kai Schutte, Benjamin Wipfler, Bernhard Misof
    Abstract:

    In this study, we investigated the relationships among insect orders with a main focus on Polyneoptera (lower Neoptera: roaches, mantids, earwigs, grasshoppers, etc.), and Paraneoptera (thrips, lice, bugs in the wide sense). The relationships between and within these groups of insects are difficult to resolve because only few informative molecular and morphological characters are available. Here, we provide the first phylogenomic expressed sequence tags data (‘EST’: short sub-sequences from a c(opy) DNA sequence encoding for proteins) for stick insects (Phasmatodea) and webspinners (Embioptera) to complete published EST data. As recent EST datasets are characterized by a heterogeneous distribution of available genes across taxa, we use different rationales to optimize the data matrix composition. Our results suggest a monophyletic origin of Polyneoptera and Eumetabola (Paraneoptera + Holometabola). However, we identified artefacts of tree reconstruction (human louse Pediculus humanus assigned to Odonata (damselflies and dragonflies) or Holometabola (insects with a complete metamorphosis); mayfly genus Baetis nested within Neoptera), which were most probably rooted in a data matrix composition bias due to the inclusion of sequence data of entire proteomes. Until entire proteomes are available for each species in phylogenomic analyses, this potential pitfall should be carefully considered.

Michael J Sharkey - One of the best experts on this subject based on the ideXlab platform.

  • Expressed sequence tags reveal Proctotrupomorpha (minus Chalcidoidea) as sister to Aculeata (Hymenoptera: Insecta)
    Molecular Phylogenetics and Evolution, 2010
    Co-Authors: Barbara J Sharanowski, S. Randal Voss, Ryan J. Yoder, John A. Walker, Barbara Robbertse, Michael J Sharkey
    Abstract:

    Hymenoptera is one of the most diverse groups of animals on the planet and have vital importance for ecosystem function as pollinators and parasitoids. Higher-level relationships among Hymenoptera have been notoriously difficult to resolve with both morphological and traditional molecular approaches. Here we examined the utility of expressed sequence tags for resolving relationships among hymenopteran superfamilies. Transcripts were assembled for 6 disparate Hymenopteran taxa with additional sequences added from public databases for a final dataset of 24 genes for 16 taxa and over 10 kb of sequence data. The concatenated dataset recovered a robust and well-supported topology demonstrating the monophyly of Holometabola, Hymenoptera, Apocrita, Aculeata, Ichneumonoidea, and a sister relationship between the two most closely related proctotrupomorphs in the dataset (Cynipoidea + Proctotrupoidea). The data strongly supported a sister relationship between Aculeata and Proctotrupomorpha, contrary to previously proposed hypotheses. Additionally there was strong evidence indicating Ichneumonoidea as sister to Aculeata + Proctotrupomorpha. These relationships were robust to missing data, nucleotide composition biases, low taxonomic sampling, and conflicting signal across gene trees. There was also strong evidence indicating that Chalcidoidea is not contained within Proctotrupomorpha.

Xavier Bellés - One of the best experts on this subject based on the ideXlab platform.

  • Comparative Transcriptomics in Two Extreme Neopterans Reveals General Trends in the Evolution of Modern Insects
    Elsevier, 2018
    Co-Authors: Guillem Ylla, Maria-dolors Piulachs, Xavier Bellés
    Abstract:

    Summary: The success of neopteran insects, with 1 million species described, is associated with developmental innovations such as holometaboly and the evolution from short to long germband 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 germband species) and the fly Drosophila melanogaster (endopterygote, Holometabolan, and long germband species). Results revealed that genes associated with metamorphosis are predominantly expressed in late nymphal stages in B. germanica and in the 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 time juvenile hormone factors appear to be unimportant. These differences possibly reflect broad trends in the evolution of development within neopterans, related to the germband type and the metamorphosis mode. : Entomology; Developmental Biology; Evolutionary Developmental Biology; Genomics Subject Areas: Entomology, Developmental Biology, Evolutionary Developmental Biology, Genomic

  • Comparative analysis of miRNA expression during the development of insects of different metamorphosis modes and germ-band types
    BMC, 2017
    Co-Authors: Guillem Ylla, Maria-dolors Piulachs, Xavier Bellés
    Abstract:

    Abstract Background Do miRNAs contribute to specify the germ-band type and the body structure in the insect embryo? Our goal was to address that issue by studying the changes in miRNA expression along the ontogeny of the German cockroach Blattella germanica, which is a short germ-band and hemimetabolan species. Results We sequenced small RNA libraries representing 11 developmental stages of B. germanica ontogeny (with especial emphasis on embryogenesis) and the changes in miRNA expression were examined. Data were compared with equivalent data for two long germ-band Holometabolan species Drosophila melanogaster and Drosophila virilis, and the short germ-band Holometabolan species Tribolium castaneum. The identification of B. germanica embryo small RNA sequences unveiled miRNAs not detected in previous studies, such as those of the MIR-309 family and 54 novel miRNAs. Four main waves of miRNA expression were recognized (with most miRNA changes occurring during the embryonic stages): the first from day 0 to day 1 of embryogenesis, the second during mid-embryogenesis (days 0–6), the third (with an acute expression peak) on day 2 of embryonic development, and the fourth during post-embryonic development. The second wave defined the boundaries of maternal-to-zygotic transition, with maternal mRNAs being cleared, presumably by Mir-309 and associated scavenger miRNAs. Conclusion miRNAs follow well-defined patterns of expression over hemimetabolan ontogeny, patterns that are more diverse during embryonic development than during the nymphal stages. The results suggest that miRNAs play important roles in the developmental transitions between the embryonic stages of development (starting with maternal loading), during which they might influence the germ-band type and metamorphosis mode

  • Insect glycerol transporters evolved by functional co-option and gene replacement
    Nature communications, 2015
    Co-Authors: Roderick Nigel Finn, François Chauvigné, Jon Anders Stavang, Xavier Bellés, Joan Cerdà
    Abstract:

    Transmembrane glycerol transport is typically facilitated by aquaglyceroporins in Prokaryota and Eukaryota. In Holometabolan insects however, aquaglyceroporins are absent, yet several species possess polyol permeable aquaporins. It thus remains unknown how glycerol transport evolved in the Holometabola. By combining phylogenetic and functional studies, here we show that a more efficient form of glycerol transporter related to the water-selective channel AQP4 specifically evolved and multiplied in the insect lineage, resulting in the replacement of the ancestral branch of aquaglyceroporins in Holometabolan insects. To recapitulate this evolutionary process, we generate specific mutants in distantly related insect aquaporins and human AQP4 and show that a single mutation in the selectivity filter converted a water-selective channel into a glycerol transporter at the root of the crown clade of hexapod insects. Integration of phanerozoic climate models suggests that these events were associated with the emergence of complete metamorphosis and the unparalleled radiation of insects.

  • broad complex functions in postembryonic development of the cockroach blattella germanica shed new light on the evolution of insect metamorphosis
    Biochimica et Biophysica Acta, 2013
    Co-Authors: Jiahsin Huang, Jesus Lozano, Xavier Bellés
    Abstract:

    article i nfo Background: Insect metamorphosis proceeds in two modes: hemimetaboly, gradual change along the life cycle; and holometaboly, abrupt change from larvae to adult mediated by a pupal stage. Both are regulated by 20-hydroxyecdysone (20E), which promotes molts, and juvenile hormone (JH), which represses adult morphogenesis. Expression of Broad-complex (BR-C) is induced by 20E and modulated by JH. In holometab- olous species, like Drosophila melanogaster, BR-C expression is inhibited by JH in young larvae and enhanced in mature larvae, when JH declines and BR-C expression specifies the pupal stage. Methods: Using Blattella germanica as a basal hemimetabolous model, we determined the patterns of expres- sion of BR-C mRNAs using quantitative RT-PCR, and we studied the functions of BR-C factors using RNA inter- ference approaches. Results: We found that BR-C expression is enhanced by JH and correlates with JH hemolymph concentration. BR-C factors appear to be involved in cell division and wing pad growth, as well as wing vein patterning. Conclusions: In B. germanica, expression of BR-C is enhanced by JH, and BR-C factors appear to promote wing growth to reach the right size, form and patterning, which contrast with the endocrine regulation and com- plex functions observed in holometabolous species. General significance: Our results shed new light to the evolution from hemimetaboly to holometaboly regard- ing BR-C, whose regulation and functions were affected by two innovations: 1) a shift in JH action on BR-C expression during young stages, from stimulatory to inhibitory, and 2) an expansion of functions, from reg- ulating wing development, to determining pupal morphogenesis.