The Experts below are selected from a list of 204 Experts worldwide ranked by ideXlab platform
Wolfgang W Weisser - One of the best experts on this subject based on the ideXlab platform.
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juvenile hormone titres and winged offspring production do not correlate in the pea aphid acyrthosiphon pisum
Journal of Insect Physiology, 2008Co-Authors: Ezra G Schwartzberg, Grit Kunert, Stephanie A Westerlund, Klaus H Hoffmann, Wolfgang W WeisserAbstract:Abstract Pea aphids, Acyrthosiphon pisum , reproduce parthenogenetically and are wing-dimorphic such that offspring can develop into winged (alate) or unwinged (apterous) adults. Alate induction is maternal and offspring phenotype is entirely determined by changes in the physiology and environment of the mother. Juvenile Hormones (JHs) have been implicated in playing a role in wing differentiation in aphids, however until recently, methods were not available to accurately quantify these Insect Hormones in small Insects such as aphids. Using a novel LC–MS approach we were able to quantify JH III in pea aphids that were either producing a high proportion of winged morphs among their offspring or mainly unwinged offspring. We measured JH III titres by pooling the hemolymph of 12 or fewer individuals (1 μL hemolymph) treated identically. Levels of JH ranged from 30 to 163 pg/μL. While aphids in the two treatments strongly differed in the proportion of winged morphs among their offspring, their JH III titres did not differ significantly. There was also no correlation between JH III titre and the proportion of winged offspring in induced aphids. This supports earlier findings that wing dimorphism in aphids may be regulated by other physiological mechanisms.
David Martínez-torres - One of the best experts on this subject based on the ideXlab platform.
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Identification of the prothoracicotropic hormone (Ptth) coding gene and localization of its site of expression in the pea aphid Acyrthosiphon pisum.
Insect molecular biology, 2017Co-Authors: Miquel Barberà, David Martínez-torresAbstract:Insect Hormones control essential aspects of physiology, behaviour and development in Insects. The majority of Insect Hormones are peptide Hormones that perform a highly diverse catalogue of functions. Prothoracicotropic hormone (PTTH) is a brain neuropeptide hormone whose main function is to stimulate the secretion of ecdysone (the moulting hormone) by the prothoracic glands in Insect larvae thus playing a key role in the control of moulting and metamorphosis. Moreover, both PTTH release or blockade have been reported to act as a switch to terminate or initiate larval and pupal diapauses. In Insects, diapause is a prevalent response often regulated by the photoperiod. It has been shown that PTTH participates as an output of the circadian clock and a role in photoperiodic processes is suggested in some Insect species. Aphids (Hemiptera: Aphididae) reproduce by cyclical parthenogenesis with a sexual phase, induced by short photoperiods, that leads to the production of diapausing eggs. With the availability of the pea aphid (Acyrthosiphon pisum) genome, efforts to identify and characterize genes relevant to essential aspects of aphid biology have multiplied. In spite of its relevance, several genomic and transcriptomic studies on aphid neuropeptides failed to detect aphid PTTH amongst them. Here we report on the first identification of the aphid PTTH coding gene and the neuroanatomical localization of its expression in the aphid brain.
Liesbeth Badisco - One of the best experts on this subject based on the ideXlab platform.
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Eat to reproduce: a key role for the insulin signaling pathway in adult Insects.
Frontiers in physiology, 2013Co-Authors: Liesbeth Badisco, Pieter Van Wielendaele, Jozef Vanden BroeckAbstract:Insects, like all heterotrophic organisms, acquire from their food the nutrients that are essential for anabolic processes that lead to growth (larval stages) or reproduction (adult stage). In adult females, this nutritional input is processed and results in a very specific output, i.e., the production of fully developed eggs ready for fertilization and deposition. An important role in this input-output transition is attributed to the insulin signaling pathway (ISP). The ISP is considered to act as a sensor of the organism's nutritional status and to stimulate the progression of anabolic events when the status is positive. In several Insect species belonging to different orders, the ISP has been demonstrated to positively control vitellogenesis and oocyte growth. Whether or not ISP acts herein via a mediator action of lipophilic Insect Hormones (ecdysteroids and juvenile hormone) remains debatable and might be differently controlled in different Insect orders. Most likely, insulin-related peptides, ecdysteroids and juvenile hormone are involved in a complex regulatory network, in which they mutually influence each other and in which the Insect's nutritional status is a crucial determinant of the network's output. The current review will present an overview of the regulatory role of the ISP in female Insect reproduction and its interaction with other pathways involving nutrients, lipophilic Hormones and neuropeptides.
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rna interference of insulin related peptide and neuroparsins affects vitellogenesis in the desert locust schistocerca gregaria
Peptides, 2011Co-Authors: Liesbeth Badisco, Elisabeth Marchal, Heleen Verlinden, Pieter Van Wielendaele, Rut Vleugels, Jozef Vanden BroeckAbstract:The 'classic' Insect Hormones, juvenile hormone and 20-hydroxyecdysone, can stimulate vitellogenesis and/or ovarian development in adult females of several Insect species. Accumulating evidence also indicates a crucial role in female reproductive physiology for peptide Hormones, such as insulin-related peptides (IRPs) and neuroparsins (NPs). Especially in dipteran species, IRP signaling has been shown to regulate female reproductive events. The first NP was originally identified from the migratory locust (Locusta migratoria) as an antigonadotropic factor that delayed vitellogenesis. Moreover, NP family members display sequence similarities with the N-terminal domain of vertebrate insulin-like growth factor binding proteins (IGFBPs). In the current study, RNA interference (RNAi) was employed to investigate the possible involvement of IRP and NPs in the control of the female desert locust (Schistocerca gregaria) reproductive system. The cDNAs encoding an IRP (Scg-IRP) and four NPs (Scg-NPs) had previously been cloned from S. gregaria. An RNAi-mediated knock-down of either Scg-NP or Scg-IRP transcript levels was induced in adult female desert locusts and the subsequent effects were analyzed. Knock-down of the Scg-NPs or Scg-IRP affected vitellogenin transcript levels and oocyte growth in a positive and negative way, respectively. The current findings are indicative for a role of Scg-NPs and Scg-IRP in the control of vitellogenin synthesis. A plausible hypothesis is that Scg-IRP may act as a sensor of the nutritional and metabolic status that determines whether vitellogenesis can occur. That the same processes were affected in opposite ways in both RNAi experiments offers an extra argument for antagonizing roles of Scg-NPs and Scg-IRP.
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Control of ecdysteroidogenesis in prothoracic glands of Insects: a review.
Peptides, 2009Co-Authors: Elisabeth Marchal, Masatoshi Iga, Sandrien Van De Velde, Liesbeth Badisco, Hans Peter Vandersmissen, Heleen Verlinden, Pieter Van Wielendaele, Roger Huybrechts, Gert Simonet, Guy SmaggheAbstract:The very first step in the study of the endocrine control of Insect molting was taken in 1922. Stefan Kopec characterized a factor in the brain of the gypsy moth, Lymantria dispar which appeared to be essential for metamorphosis. This factor was later identified as the neuropeptide prothoracicotropic hormone (PTTH), the first discovery of a series of factors involved in the regulation of ecdysteroid biosynthesis in Insects. It is now accepted that PTTH is the most important regulator of prothoracic gland (PG) ecdysteroidogenesis. The periodic increases in ecdysteroid titer necessary for Insect development can basically be explained by the episodic activation of the PGs by PTTH. However, since the characterization of the prothoracicostatic hormone (PTSH), it has become clear that in addition to 'tropic factors', also 'static factors', which are responsible for the 'fine-tuning' of the hemolymph ecdysteroid titer, are at play. Many of these regulatory factors are peptides originating from the brain, but also other, extracerebral factors both of peptidic and non-peptidic nature are able to affect PG ecdysteroidogenesis, such as the 'classic' Insect Hormones, juvenile hormone (JH) and the molting hormone (20E) itself. The complex secretory pattern of ecdysteroids as observed in vivo is the result of the delicate balance and interplay between these ecdysiotropic and ecdysiostatic factors.
Michael E Scharf - One of the best experts on this subject based on the ideXlab platform.
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phenotypic impacts of pban rna interference in an ant solenopsis invicta and a moth helicoverpa zea
Journal of Insect Physiology, 2012Co-Authors: Man-yeon Choi, Robert Vander K Meer, Michael E ScharfAbstract:Insect neuropeptide Hormones represent more than 90% of all Insect Hormones. The PBAN/pyrokinin family is a major group of Insect neuropeptides, and they are expected to be found from all Insect groups. These species-specific neuropeptides have been shown to have a variety of functions from embryo to adult. PBAN is well understood in moth species relative to sex pheromone biosynthesis, but other potential functions are yet to be determined. Recently, we focused on defining the PBAN gene and peptides in fire ants in preparation for an investigation of their function(s). RNA interference (RNAi) technology is a convenient tool to investigate unknown physiological functions in Insects, and it is now an emerging method for development of novel biologically-based control agents as alternatives to Insecticides. This could be a paradigm shift that will avoid many problems associated with conventional chemical Insecticides. In this study, we selected the PBAN gene and its neuropeptide products as an RNAi target from two Insect groups; a social Insect, the fire ant (Solenopsis invicta) and a non-social Insect, the corn earworm (Helicoverpa zea). Both Insects are economically important pests. We report negative impacts after PBAN dsRNA treatment to suppress PBAN gene transcription during developmental and adult stages of both species, e.g. increased adult and larval mortality, delayed pupal development and decreased sex pheromone production in the moth. This is an important first step in determining the multiple functions of the PBAN gene in these two Insects. This work illustrates the variety of phenotypic effects observed after RNAi silencing of the PBAN gene and suggests the possibility of novel biologically-based Insect pest control methods.
Pieter Van Wielendaele - One of the best experts on this subject based on the ideXlab platform.
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Eat to reproduce: a key role for the insulin signaling pathway in adult Insects.
Frontiers in physiology, 2013Co-Authors: Liesbeth Badisco, Pieter Van Wielendaele, Jozef Vanden BroeckAbstract:Insects, like all heterotrophic organisms, acquire from their food the nutrients that are essential for anabolic processes that lead to growth (larval stages) or reproduction (adult stage). In adult females, this nutritional input is processed and results in a very specific output, i.e., the production of fully developed eggs ready for fertilization and deposition. An important role in this input-output transition is attributed to the insulin signaling pathway (ISP). The ISP is considered to act as a sensor of the organism's nutritional status and to stimulate the progression of anabolic events when the status is positive. In several Insect species belonging to different orders, the ISP has been demonstrated to positively control vitellogenesis and oocyte growth. Whether or not ISP acts herein via a mediator action of lipophilic Insect Hormones (ecdysteroids and juvenile hormone) remains debatable and might be differently controlled in different Insect orders. Most likely, insulin-related peptides, ecdysteroids and juvenile hormone are involved in a complex regulatory network, in which they mutually influence each other and in which the Insect's nutritional status is a crucial determinant of the network's output. The current review will present an overview of the regulatory role of the ISP in female Insect reproduction and its interaction with other pathways involving nutrients, lipophilic Hormones and neuropeptides.
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rna interference of insulin related peptide and neuroparsins affects vitellogenesis in the desert locust schistocerca gregaria
Peptides, 2011Co-Authors: Liesbeth Badisco, Elisabeth Marchal, Heleen Verlinden, Pieter Van Wielendaele, Rut Vleugels, Jozef Vanden BroeckAbstract:The 'classic' Insect Hormones, juvenile hormone and 20-hydroxyecdysone, can stimulate vitellogenesis and/or ovarian development in adult females of several Insect species. Accumulating evidence also indicates a crucial role in female reproductive physiology for peptide Hormones, such as insulin-related peptides (IRPs) and neuroparsins (NPs). Especially in dipteran species, IRP signaling has been shown to regulate female reproductive events. The first NP was originally identified from the migratory locust (Locusta migratoria) as an antigonadotropic factor that delayed vitellogenesis. Moreover, NP family members display sequence similarities with the N-terminal domain of vertebrate insulin-like growth factor binding proteins (IGFBPs). In the current study, RNA interference (RNAi) was employed to investigate the possible involvement of IRP and NPs in the control of the female desert locust (Schistocerca gregaria) reproductive system. The cDNAs encoding an IRP (Scg-IRP) and four NPs (Scg-NPs) had previously been cloned from S. gregaria. An RNAi-mediated knock-down of either Scg-NP or Scg-IRP transcript levels was induced in adult female desert locusts and the subsequent effects were analyzed. Knock-down of the Scg-NPs or Scg-IRP affected vitellogenin transcript levels and oocyte growth in a positive and negative way, respectively. The current findings are indicative for a role of Scg-NPs and Scg-IRP in the control of vitellogenin synthesis. A plausible hypothesis is that Scg-IRP may act as a sensor of the nutritional and metabolic status that determines whether vitellogenesis can occur. That the same processes were affected in opposite ways in both RNAi experiments offers an extra argument for antagonizing roles of Scg-NPs and Scg-IRP.
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Control of ecdysteroidogenesis in prothoracic glands of Insects: a review.
Peptides, 2009Co-Authors: Elisabeth Marchal, Masatoshi Iga, Sandrien Van De Velde, Liesbeth Badisco, Hans Peter Vandersmissen, Heleen Verlinden, Pieter Van Wielendaele, Roger Huybrechts, Gert Simonet, Guy SmaggheAbstract:The very first step in the study of the endocrine control of Insect molting was taken in 1922. Stefan Kopec characterized a factor in the brain of the gypsy moth, Lymantria dispar which appeared to be essential for metamorphosis. This factor was later identified as the neuropeptide prothoracicotropic hormone (PTTH), the first discovery of a series of factors involved in the regulation of ecdysteroid biosynthesis in Insects. It is now accepted that PTTH is the most important regulator of prothoracic gland (PG) ecdysteroidogenesis. The periodic increases in ecdysteroid titer necessary for Insect development can basically be explained by the episodic activation of the PGs by PTTH. However, since the characterization of the prothoracicostatic hormone (PTSH), it has become clear that in addition to 'tropic factors', also 'static factors', which are responsible for the 'fine-tuning' of the hemolymph ecdysteroid titer, are at play. Many of these regulatory factors are peptides originating from the brain, but also other, extracerebral factors both of peptidic and non-peptidic nature are able to affect PG ecdysteroidogenesis, such as the 'classic' Insect Hormones, juvenile hormone (JH) and the molting hormone (20E) itself. The complex secretory pattern of ecdysteroids as observed in vivo is the result of the delicate balance and interplay between these ecdysiotropic and ecdysiostatic factors.