Broad specifies pupal development and mediates the ‘status quo’ action of juvenile hormone on the pupal-adult transformation inDrosophilaandManduca

Development ◽  
2002 ◽  
Vol 129 (9) ◽  
pp. 2259-2269 ◽  
Author(s):  
Xiaofeng Zhou ◽  
Lynn M. Riddiford
Keyword(s):  
Juvenile Hormone ◽  
Adult Development ◽  
Pupal Stage ◽  
Status Quo ◽  
Endocrine Control ◽  
The Status ◽  
Insect Metamorphosis ◽  
Adult Transformation ◽  
Late Expression ◽  
Pupal Cuticle

The understanding of the molecular basis of the endocrine control of insect metamorphosis has been hampered by the profound differences in responses of the Lepidoptera and the Diptera to juvenile hormone (JH). In both Manduca and Drosophila, the broad (br) gene is expressed in the epidermis during the formation of the pupa, but not during adult differentiation. Misexpression of BR-Z1 during either a larval or an adult molt of Drosophila suppressed stage-specific cuticle genes and activated pupal cuticle genes, showing that br is a major specifier of the pupal stage. Treatment with a JH mimic at the onset of the adult molt causes br re-expression and the formation of a second pupal cuticle in Manduca, but only in the abdomen of Drosophila. Expression of the BR isoforms during adult development of Drosophila suppressed bristle and hair formation when induced early or redirected cuticle production toward the pupal program when induced late. Expression of BR-Z1 at both of these times mimicked the effect of JH application but, unlike JH, it caused production of a new pupal cuticle on the head and thorax as well as on the abdomen. Consequently, the ‘status quo’ action of JH on the pupal-adult transformation is mediated by the JH-induced re-expression of BR.

scholarly journals Molecular mechanism underlying juvenile hormone-mediated repression of precocious larval–adult metamorphosis

2017 ◽  
Vol 114 (5) ◽  
pp. 1057-1062 ◽  
Author(s):  
Takumi Kayukawa ◽  
Akiya Jouraku ◽  
Yuka Ito ◽  
Tetsuro Shinoda
Keyword(s):  
Juvenile Hormone ◽  
Cell Line ◽  
Adult Development ◽  
Transcriptional Repression ◽  
Molecular Mechanisms ◽  
Pupal Stage ◽  
Genetic Network ◽  
Holometabolous Insect ◽  
Insect Metamorphosis ◽  
Krüppel Homolog 1

Juvenile hormone (JH) represses precocious metamorphosis of larval to pupal and adult transitions in holometabolous insects. The early JH-inducible geneKrüppel homolog 1(Kr-h1) plays a key role in the repression of metamorphosis as a mediator of JH action. Previous studies demonstrated that Kr-h1 inhibits precocious larval–pupal transition in immature larva via direct transcriptional repression of the pupal specifierBroad-Complex(BR-C). JH was recently reported to repress the adult specifier geneEcdysone-induced protein 93F(E93); however, its mechanism of action remains unclear. Here, we found that JH suppressed ecdysone-inducibleE93expression in the epidermis of the silkwormBombyx moriand in aB. moricell line. Reporter assays in the cell line revealed that the JH-dependent suppression was mediated by Kr-h1. Genome-wide ChIP-seq analysis identified a consensus Kr-h1 binding site (KBS, 14 bp) located in theE93promoter region, and EMSA confirmed that Kr-h1 directly binds to the KBS. Moreover, we identified a C-terminal conserved domain in Kr-h1 essential for the transcriptional repression ofE93. Based on these results, we propose a mechanism in which JH-inducible Kr-h1 directly binds to the KBS site upstream of theE93locus to repress its transcription in a cell-autonomous manner, thereby preventing larva from bypassing the pupal stage and progressing to precocious adult development. These findings help to elucidate the molecular mechanisms regulating the metamorphic genetic network, including the functional significance ofKr-h1,BR-C, andE93in holometabolous insect metamorphosis.

scholarly journals E93 expression and links to the juvenile hormone in hemipteran mealybugs with insights on female neoteny

2018 ◽  
Author(s):  
Isabelle Mifom Vea ◽  
Sayumi Tanaka ◽  
Tomohiro Tsuji ◽  
Takahiro Shiotsuki ◽  
Akiya Jouraku ◽  
...  
Keyword(s):  
Juvenile Hormone ◽  
Adult Development ◽  
Molecular Mechanisms ◽  
Expression Patterns ◽  
Scale Insects ◽  
List Type ◽  
Male Adult ◽  
Male Development ◽  
Juvenile Hormone Mimic ◽  
Insect Metamorphosis

AbstractInsect metamorphosis generates reproductive adults and is commonly accompanied by the direct or indirect development of wings. In some winged insects, the imago is altered by life history changes. For instance, in scale insects and mealybugs, reproductive females retain juvenile features and are wingless. The transcription factor E93 triggers metamorphosis and plays in concert with the juvenile hormone pathway to guarantee the successful transition from juvenile to adult. We previously provided evidence of an atypical down-regulation of the juvenile hormone pathway during female adult development in the Japanese mealybug. Here, we further investigate how E93 is involved in the production of neotenic wingless females, by identifying its isoforms, assessing their expression patterns and evaluating the effect of exogenous juvenile hormone mimic treatment on E93. This study identifies three E93 isoforms on the 5’ end based on Japanese mealybug cDNA and shows that female development occurs with the near absence of E93 transcripts, as opposed to male metamorphosis. Additionally, while male development is typically affected by exogenous juvenile hormone mimic treatments, females seem to remain insensitive to the treatment, and up-regulation of the juvenile hormone signaling is not observed. Furthermore, juvenile hormone mimic treatment on female nymphs did not have obvious effect on E93 transcription, while treatment on male prepupae resulted in decreased E93 transcripts. In this study, we emphasize the importance of examining cases of atypical metamorphosis as complementary systems to provide a better understanding on the molecular mechanisms underlying insect metamorphosis. For instance, the factors regulating the expression of E93 are largely unclear. Investigating the regulatory mechanism of E93 transcription could provide clues towards identifying the factors that induce or suppress E93 transcription, in turn triggering male adult development or female neoteny.Graphical abstractHighlights- Neotenic female Planococcus kraunhiae (Japanese mealybug) develops with low E93 expression.- E93 expression pattern during male development is typical to other insects.- Juvenile hormone mimic treatment on male prepupae results in decreased E93 transcripts.- Juvenile hormone mimic treatment on female nymphs does not have obvious effects on E93 transcription.- Female mealybugs have low sensitivity to juvenile hormone mimic treatments compared to males and other insects.

scholarly journals IMMUNOLOGICAL STUDIES OF INSECT METAMORPHOSIS

1954 ◽  
Vol 37 (4) ◽  
pp. 539-558 ◽  
Author(s):  
William H. Telfer
Keyword(s):  
Concentration Gradient ◽  
Maximum Concentration ◽  
Liquid Fraction ◽  
Pupal Stage ◽  
Detectable Amount ◽  
Clear Liquid ◽  
Egg Formation ◽  
Insect Metamorphosis ◽  
Adult Transformation ◽  
Lines Of Evidence

1. In the pupal stage of the cecropia silkworm, antigen 7, a protein with the solubility characteristics of an albumin, is present in female blood in approximately a thousand times higher concentration than in the blood of males. Antigen 7 is undetectable in the blood of larvae of either sex. It first appears in the blood after the larva has spun its cocoon, and is present throughout all subsequent stages of metamorphosis. Late in the pupal-adult transformation, when the eggs are produced, the concentration of antigen 7 in female blood decreases significantly. 2. An antigen which could not be distinguished from antigen 7 immunologically is present in solution in the yolk of unfertilized eggs. 3. In females which, by ovariectomy, were prevented from forming eggs, the concentration of antigen 7 in the blood increased during the usual period of egg formation rather than undergoing the normal decrease. Ovaries transferred to the hemocoel of males produced eggs but were unable to incorporate antigen 7 in the yolk unless a detectable amount of the protein was present in the blood. The ovaries of polyphemus females which had been transfused with cecropia blood incorporated cecropia antigen 7 into the eggs they produced. These lines of evidence indicate that antigen 7 is secreted into the blood by some tissue other than the ovaries, and that it is subsequently drawn from the blood and deposited in the yolk. 4. The concentration of antigen 7 in the clear, liquid fraction of the yolk is four times higher than the maximum concentration attained in the blood during metamorphosis, and twenty times higher than that of the blood at the conclusion of egg formation. The protein thus appears to be transferred from blood to yolk against a concentration gradient.

scholarly journals TGF-β signaling in insects regulates metamorphosis via juvenile hormone biosynthesis

2016 ◽  
Vol 113 (20) ◽  
pp. 5634-5639 ◽  
Author(s):  
Yoshiyasu Ishimaru ◽  
Sayuri Tomonari ◽  
Yuji Matsuoka ◽  
Takahito Watanabe ◽  
Katsuyuki Miyawaki ◽  
...  
Keyword(s):  
Juvenile Hormone ◽  
Transcriptional Activation ◽  
Pupal Stage ◽  
Corpora Allata ◽  
Nymphal Instar ◽  
Morphological Transformation ◽  
Endocrine Control ◽  
Gene Encoding ◽  
Juvenile Hormone Biosynthesis ◽  
Morphogenetic Protein

Although butterflies undergo a dramatic morphological transformation from larva to adult via a pupal stage (holometamorphosis), crickets undergo a metamorphosis from nymph to adult without formation of a pupa (hemimetamorphosis). Despite these differences, both processes are regulated by common mechanisms that involve 20-hydroxyecdysone (20E) and juvenile hormone (JH). JH regulates many aspects of insect physiology, such as development, reproduction, diapause, and metamorphosis. Consequently, strict regulation of JH levels is crucial throughout an insect’s life cycle. However, it remains unclear how JH synthesis is regulated. Here, we report that in the corpora allata of the cricket, Gryllus bimaculatus, Myoglianin (Gb’Myo), a homolog of Drosophila Myoglianin/vertebrate GDF8/11, is involved in the down-regulation of JH production by suppressing the expression of a gene encoding JH acid O-methyltransferase, Gb’jhamt. In contrast, JH production is up-regulated by Decapentaplegic (Gb’Dpp) and Glass-bottom boat/60A (Gb’Gbb) signaling that occurs as part of the transcriptional activation of Gb’jhamt. Gb’Myo defines the nature of each developmental transition by regulating JH titer and the interactions between JH and 20E. When Gb’myo expression is suppressed, the activation of Gb’jhamt expression and secretion of 20E induce molting, thereby leading to the next instar before the last nymphal instar. Conversely, high Gb’myo expression induces metamorphosis during the last nymphal instar through the cessation of JH synthesis. Gb’myo also regulates final insect size. Because Myo/GDF8/11 and Dpp/bone morphogenetic protein (BMP)2/4-Gbb/BMP5–8 are conserved in both invertebrates and vertebrates, the present findings provide common regulatory mechanisms for endocrine control of animal development.

Juvenile hormone: The status of its “status quo” action

1996 ◽  
Vol 32 (3-4) ◽  
pp. 271-286 ◽  
Author(s):  
Lynn M. Riddiford
Keyword(s):  
Juvenile Hormone ◽  
Status Quo ◽  
The Status

scholarly journals Where did the pupa come from? The timing of juvenile hormone signalling supports homology between stages of hemimetabolous and holometabolous insects

2019 ◽  
Vol 374 (1783) ◽  
pp. 20190064 ◽  
Author(s):  
Marek Jindra
Keyword(s):  
Juvenile Hormone ◽  
Adult Development ◽  
Intermediate Stage ◽  
Selective Advantage ◽  
Postembryonic Development ◽  
Form And Function ◽  
Insect Metamorphosis ◽  
Alternative Hypotheses ◽  
Complete Metamorphosis ◽  
Hormone Signalling

Insect metamorphosis boasts spectacular cases of postembryonic development when juveniles undergo massive morphogenesis before attaining the adult form and function; in moths or flies the larvae do not even remotely resemble their adult parents. A selective advantage of complete metamorphosis (holometaboly) is that within one species the two forms with different lifestyles can exploit diverse habitats. It was the environmental adaptation and specialization of larvae, primarily the delay and internalization of wing development, that eventually required an intermediate stage that we call a pupa. It is a long-held and parsimonious hypothesis that the holometabolous pupa evolved through modification of a final juvenile stage of an ancestor developing through incomplete metamorphosis (hemimetaboly). Alternative hypotheses see the pupa as an equivalent of all hemimetabolous moulting cycles (instars) collapsed into one, and consider any preceding holometabolous larval instars free-living embryos stalled in development. Discoveries on juvenile hormone signalling that controls metamorphosis grant new support to the former hypothesis deriving the pupa from a final pre-adult stage. The timing of expression of genes that repress and promote adult development downstream of hormonal signals supports homology between postembryonic stages of hemimetabolous and holometabolous insects. This article is part of the theme issue ‘The evolution of complete metamorphosis’.

scholarly journals Juvenile Hormone: The Status of “Status Quo”

1981 ◽  
Vol 21 (3) ◽  
pp. 763-773 ◽  
Author(s):  
JUDITH H. WILLIS
Keyword(s):  
Juvenile Hormone ◽  
Status Quo ◽  
The Status

scholarly journals IMMUNOLOGICAL STUDIES OF INSECT METAMORPHOSIS

1953 ◽  
Vol 36 (3) ◽  
pp. 389-413 ◽  
Author(s):  
William H. Telfer ◽  
Carroll M. Williams
Keyword(s):  
Adult Development ◽  
Larval Instar ◽  
Pupal Stage ◽  
Close Correlation ◽  
Fourth Instar ◽  
Systematic Change ◽  
Physiological Mechanisms ◽  
Insect Metamorphosis ◽  
Concentration Changes ◽  
Antigen Antibody

1. The cell-free blood of the Cecropia silkworm produces a maximum of nine bands of antigen-antibody precipitate when reacted in antiserum-agar tests with antisera prepared by injecting Cecropia extracts into rabbits. The blood antigens producing these bands of precipitate have the properties of proteins in that they are non-dialyzable, labile at 75°C., and salted out by 75 per cent saturated ammonium sulfate. One antigen was identified as a carotenoid protein. 2. Six bands of precipitate were selected for further study. Absorption tests revealed that the blood, at all stages of metamorphosis, is capable of precipitating the antibodies which produce five of these bands. This result indicates that five of the six antigens are present in the blood throughout metamorphosis. The sixth antigen is undetectable in blood from fourth instar larvae, appears in the blood late in the fifth instar, persists during the pupal stage, and disappears again during adult development. 3. When blood samples from various stages of metamorphosis were tested in antiserum-agar tubes, the rates of advance of the six bands of precipitate underwent systematic change in close correlation with the morphological stage of the silkworm's metamorphosis. These changes are interpreted in terms of concentration changes of the corresponding blood antigens. The validity of this interpretation was tested in several ways, with the conclusion that the interpretation was generally acceptable for the system under consideration. 4. All six antigens appear to increase in concentration during the last larval instar and to decrease in concentration during the period of adult development. However, each antigen has its own characteristic pattern of concentration change which differs from those of the other five. In order to explain this diversity, we conclude that the physiological mechanisms which regulate the synthesis and utilization of the blood antigens control each antigen on an individual basis.

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