The Experts below are selected from a list of 2118 Experts worldwide ranked by ideXlab platform
Demar Taylor - One of the best experts on this subject based on the ideXlab platform.
-
ovarian ecdysteroidogenesis in both immature and mature stages of an acari ornithodoros moubata
PLOS ONE, 2015Co-Authors: Mari H. Ogihara, Demar Taylor, Yutaka Suzuki, Juri Hikiba, Hiroshi KataokaAbstract:Ecdysteroidogenesis is essential for arthropod development and reproduction. Although the importance of Ecdysteroids has been demonstrated, there is little information on the sites and enzymes for synthesis of Ecdysteroids from Chelicerates. Ecdysteroid functions have been well studied in the soft tick Ornithodoros moubata, making this species an excellent candidate for elucidating ecdysteroidogenesis in Chelicerates. Results showed that O. moubata has at least two ecdysteroidogenic enzymes, Spook (OmSpo) and Shade (OmShd). RNAi showed both enzymes were required for ecdysteroidogenesis. Enzymatic assays demonstrated OmShd has the conserved functions of ecdysone 20-hydroxylase. OmSpo showed specific expression in the ovaries of final nymphal and adult stages, indicating O. moubata utilizes the ovary as an ecdysteroidogenic tissue instead of specific tissues as seen in other arthropods. On the other hand, OmShd expression was observed in various tissues including the midgut, indicating functional Ecdysteroids can be produced in these tissues. In nymphal stages, expression of both OmSpo and OmShd peaked before molting corresponding with high ecdysteroid titers in the hemolymph. In fed adult females, OmSpo expression peaked at 8–10 days after engorgement, while OmShd expression peaked immediately after engorgement. Mated females showed more frequent surges of OmShd than virgin females. These results indicate that the regulation of synthesis of Ecdysteroids differs in nymphs and adult females, and mating modifies adult female ecdysteroidogenesis. This is the first report to focus on synthesis of Ecdysteroids in ticks and provides essential knowledge for understanding the evolution of ecdysteroidogenesis in arthropods.
-
cloning and expression of the ecdysteroid receptor during ecdysis and reproduction in females of the soft tick ornithodoros moubata acari argasidae
Insect Molecular Biology, 2007Co-Authors: Mari Horigane, Yoshiro Nakajima, Kazumasa Ogihara, T Shinoda, Demar TaylorAbstract:Molecular mechanisms of ecdysteroid regulation in development and reproduction have been thoroughly investigated in Diptera and Lepidoptera, but few studies report the molecular actions of Ecdysteroids in hemimetabolous insects and more primitive arthropods. Ecdysteroids appear to be the main hormones regulating development and vitellogenesis in ticks. An ecdysteroid receptor that showed high homology with EcRs of other arthropods was isolated from Ornithodoros moubata (OmEcRA). OmEcR expression patterns coincided with ecdysteroid titres in the haemolymph during moulting and vitellogenesis and differed between mated and virgin females. Therefore, OmEcR appears to mediate the regulation of moulting and vitellogenesis by Ecdysteroids in O. moubata females as seen in other arthropods.
-
ecdysteroid hormone titer and its relationship to vitellogenesis in the soft tick ornithodoros moubata acari argasidae
General and Comparative Endocrinology, 2007Co-Authors: Kazumasa Ogihara, Yoshiro Nakajima, Mari Horigane, Atsuko Moribayashi, Demar TaylorAbstract:A blood meal is required for reproduction in most argasid female ticks. The blood meal appears to stimulate an organ in the posterior end to produce a fat body stimulating factor (FSF), which is thought to be an ecdysteroid, to induce vitellogenin (Vg) synthesis. In this study, the relationship of vitellogenesis and Ecdysteroids was investigated by measuring Vg and ecdysteroid titers while observing oocyte development and oviposition in mated and virgin females. Oviposition occurred from day 10 after engorgement in mated females and continued up to 40-50 days, whereas egg maturation and oviposition did not occur in virgin females. Vg titers in the hemolymph peaked on day 6 after engorgement and subsequently declined in mated females. Interestingly, Vg synthesis occurred and ovarian development progressed to the development of early vitellogenic oocytes in virgin females but oocyte maturation and oviposition did not occur. Topical application of Ecdysteroids induced oviposition in fed virgin females indicating that Ecdysteroids may induce oviposition. Concentrations of Ecdysteroids for 20 days after engorgement revealed several peaks in mated female whole body extracts, but no peaks in virgin female extracts. In the hemolymph of only mated females, ecdysteroid titers showed two peaks that followed the early peak of Ecdysteroids in the whole body on day 4 and 6 after engorgement. In addition, Ecdysteroids in the reproductive tissues increased with the development of the ovary in mated females and this increase coincided with the latter peaks of the whole body. These observations indicate that physiological elevation of Ecdysteroids accelerate Vg synthesis, and may induce egg maturation and stimulate oviposition in fed mated Ornithodoros moubata females.
Mari Horigane - One of the best experts on this subject based on the ideXlab platform.
-
cloning and expression of the ecdysteroid receptor during ecdysis and reproduction in females of the soft tick ornithodoros moubata acari argasidae
Insect Molecular Biology, 2007Co-Authors: Mari Horigane, Yoshiro Nakajima, Kazumasa Ogihara, T Shinoda, Demar TaylorAbstract:Molecular mechanisms of ecdysteroid regulation in development and reproduction have been thoroughly investigated in Diptera and Lepidoptera, but few studies report the molecular actions of Ecdysteroids in hemimetabolous insects and more primitive arthropods. Ecdysteroids appear to be the main hormones regulating development and vitellogenesis in ticks. An ecdysteroid receptor that showed high homology with EcRs of other arthropods was isolated from Ornithodoros moubata (OmEcRA). OmEcR expression patterns coincided with ecdysteroid titres in the haemolymph during moulting and vitellogenesis and differed between mated and virgin females. Therefore, OmEcR appears to mediate the regulation of moulting and vitellogenesis by Ecdysteroids in O. moubata females as seen in other arthropods.
-
ecdysteroid hormone titer and its relationship to vitellogenesis in the soft tick ornithodoros moubata acari argasidae
General and Comparative Endocrinology, 2007Co-Authors: Kazumasa Ogihara, Yoshiro Nakajima, Mari Horigane, Atsuko Moribayashi, Demar TaylorAbstract:A blood meal is required for reproduction in most argasid female ticks. The blood meal appears to stimulate an organ in the posterior end to produce a fat body stimulating factor (FSF), which is thought to be an ecdysteroid, to induce vitellogenin (Vg) synthesis. In this study, the relationship of vitellogenesis and Ecdysteroids was investigated by measuring Vg and ecdysteroid titers while observing oocyte development and oviposition in mated and virgin females. Oviposition occurred from day 10 after engorgement in mated females and continued up to 40-50 days, whereas egg maturation and oviposition did not occur in virgin females. Vg titers in the hemolymph peaked on day 6 after engorgement and subsequently declined in mated females. Interestingly, Vg synthesis occurred and ovarian development progressed to the development of early vitellogenic oocytes in virgin females but oocyte maturation and oviposition did not occur. Topical application of Ecdysteroids induced oviposition in fed virgin females indicating that Ecdysteroids may induce oviposition. Concentrations of Ecdysteroids for 20 days after engorgement revealed several peaks in mated female whole body extracts, but no peaks in virgin female extracts. In the hemolymph of only mated females, ecdysteroid titers showed two peaks that followed the early peak of Ecdysteroids in the whole body on day 4 and 6 after engorgement. In addition, Ecdysteroids in the reproductive tissues increased with the development of the ovary in mated females and this increase coincided with the latter peaks of the whole body. These observations indicate that physiological elevation of Ecdysteroids accelerate Vg synthesis, and may induce egg maturation and stimulate oviposition in fed mated Ornithodoros moubata females.
Kazumasa Ogihara - One of the best experts on this subject based on the ideXlab platform.
-
cloning and expression of the ecdysteroid receptor during ecdysis and reproduction in females of the soft tick ornithodoros moubata acari argasidae
Insect Molecular Biology, 2007Co-Authors: Mari Horigane, Yoshiro Nakajima, Kazumasa Ogihara, T Shinoda, Demar TaylorAbstract:Molecular mechanisms of ecdysteroid regulation in development and reproduction have been thoroughly investigated in Diptera and Lepidoptera, but few studies report the molecular actions of Ecdysteroids in hemimetabolous insects and more primitive arthropods. Ecdysteroids appear to be the main hormones regulating development and vitellogenesis in ticks. An ecdysteroid receptor that showed high homology with EcRs of other arthropods was isolated from Ornithodoros moubata (OmEcRA). OmEcR expression patterns coincided with ecdysteroid titres in the haemolymph during moulting and vitellogenesis and differed between mated and virgin females. Therefore, OmEcR appears to mediate the regulation of moulting and vitellogenesis by Ecdysteroids in O. moubata females as seen in other arthropods.
-
ecdysteroid hormone titer and its relationship to vitellogenesis in the soft tick ornithodoros moubata acari argasidae
General and Comparative Endocrinology, 2007Co-Authors: Kazumasa Ogihara, Yoshiro Nakajima, Mari Horigane, Atsuko Moribayashi, Demar TaylorAbstract:A blood meal is required for reproduction in most argasid female ticks. The blood meal appears to stimulate an organ in the posterior end to produce a fat body stimulating factor (FSF), which is thought to be an ecdysteroid, to induce vitellogenin (Vg) synthesis. In this study, the relationship of vitellogenesis and Ecdysteroids was investigated by measuring Vg and ecdysteroid titers while observing oocyte development and oviposition in mated and virgin females. Oviposition occurred from day 10 after engorgement in mated females and continued up to 40-50 days, whereas egg maturation and oviposition did not occur in virgin females. Vg titers in the hemolymph peaked on day 6 after engorgement and subsequently declined in mated females. Interestingly, Vg synthesis occurred and ovarian development progressed to the development of early vitellogenic oocytes in virgin females but oocyte maturation and oviposition did not occur. Topical application of Ecdysteroids induced oviposition in fed virgin females indicating that Ecdysteroids may induce oviposition. Concentrations of Ecdysteroids for 20 days after engorgement revealed several peaks in mated female whole body extracts, but no peaks in virgin female extracts. In the hemolymph of only mated females, ecdysteroid titers showed two peaks that followed the early peak of Ecdysteroids in the whole body on day 4 and 6 after engorgement. In addition, Ecdysteroids in the reproductive tissues increased with the development of the ovary in mated females and this increase coincided with the latter peaks of the whole body. These observations indicate that physiological elevation of Ecdysteroids accelerate Vg synthesis, and may induce egg maturation and stimulate oviposition in fed mated Ornithodoros moubata females.
René Lafont - One of the best experts on this subject based on the ideXlab platform.
-
Ecdysteroids from chenopodium quinoa willd an ancient andean crop of high nutritional value
Food Chemistry, 2011Co-Authors: Annick Maria, Jeanpierre Girault, Saowanee Kumpun, Sophie Crouzet, Nathalie Evrardtodeschi, René LafontAbstract:Abstract Chenopodium quinoa Willd. (=quinoa) is a crop cultivated since ancient times by the Incas, which has a high nutritional value. Quinoa belongs to Chenopodiaceae, a family containing many ecdysteroid-containing species, including spinach. Quinoa seeds have been investigated for their ecdysteroid content. Besides large amounts of 20-hydroxyecdysone, they contain lower amounts of makisterone A, 24- epi -makisterone A, 24(28)-dehydromakisterone A and polypodine B, together with a wide array of minor Ecdysteroids, among which three were isolated as new natural compounds, i.e. 24,25-dehydroinokosterone, 25,27-dehydroinokosterone and 5β-hydroxy-24(28)-dehydromakisterone A. Ecdysteroids are concentrated in the bran, and their amount varies with the quinoa variety used. Most of the 20-hydroxyecdysone is recovered undegraded within the seeds even after 20 min boiling, and is thus susceptible to evoke significant (beneficial) pharmacological effects on humans who eat quinoa regularly. The same applies to most quinoa-based foods, which retain most of their original ecdysteroid content.
-
The metabolism of 20-hydroxyecdysone in mice: Relevance to pharmacological effects and gene switch applications of Ecdysteroids
Journal of Steroid Biochemistry and Molecular Biology, 2011Co-Authors: Saowanee Kumpun, C. Dauphin-villemant, Catherine Blais, Annick Maria, Laurence Dinan, Boonek Yingyongnarongkul, Apichart Suksamrarn, Jeanpierre Girault, René LafontAbstract:Ecdysteroids exert many pharmacological effects in mammals (including humans), most of which appear beneficial, but their mechanism of action is far from understood. Whether they act directly and/or after the formation of metabolites is still an open question. The need to investigate this question has gained extra impetus because of the recent development of ecdysteroid-based gene-therapy systems for mammals. In order to investigate the metabolic fate of Ecdysteroids in mice, [1 ,2 -3H]20-hydroxyecdysone was prepared and injected intraperitoneally to mice. Their excretory products (urine + faeces) were collected and the different tritiated metabolites were isolated and identified. The pattern of ecdysteroid metabolites is very complex, but no conjugates were found, in contrast to the classical fate of the (less polar) endogenous vertebrate steroid hormones. Primary reactions involve dehydroxylation at C-14 and sidechain cleavage between C-20 and C-22, thereby yielding 14-deoxy-20-hydroxyecdysone, poststerone and 14-deoxypoststerone. These metabolites then undergo several reactions of reduction involving, in particular, the 6-keto-group. Anovel major metabolite has been identified as 2 β,3 β ,6 α ,22R,25 -pentahydroxy-5β-cholest-8(14)-ene. The formation of this and the other major metabolites is discussed in relation to the various effects of Ecdysteroids already demonstrated on vertebrates.
-
Characterization of Ecdysteroids in Drosophila melanogaster by enzyme immunoassay and nano-liquid chromatography-tandem mass spectrometry.
Journal of chromatography. B Analytical technologies in the biomedical and life sciences, 2010Co-Authors: Catherine Blais, Thierry Blasco, C. Dauphin-villemant, Annick Maria, René LafontAbstract:Ecdysteroids are polyhydroxylated steroids that function as molting hormones in insects. 20-Hydroxyecdysone (a 27C-ecdysteroid) is classically considered as the major steroid hormone of Drosophilamelanogaster, but this insect also contains 28C-Ecdysteroids. This arises from both the use of several dietary sterols as precursors for the synthesis of its steroid hormones, and its inability to dealkylate the 28C-phytosterols to produce cholesterol. The nature of Drosophila Ecdysteroids has been re-investigated using both high-performance liquid chromatography coupled to enzyme immunoassay and a particularly sensitive nano-liquid chromatography-mass spectrometry methodology, while taking advantage of recently available ecdysteroid standards isolated from plants. In vitro incubations of the larval steroidogenic organ, the ring-gland, reveals the synthesis of ecdysone, 20-deoxy-makisterone A and a third less polar compound identified as the 24-epimer of the latter, while wandering larvae contain the three corresponding 20-hydroxylated Ecdysteroids. This pattern results from the simultaneous use of higher plant sterols (from maize) and fungal sterols (from yeast). The physiological relevance of all these Ecdysteroids, which display different affinities to the ecdysteroid receptors, is still a matter of debate.
-
the phytoecdysteroid profiles of 7 species of silene caryophyllaceae
Archives of Insect Biochemistry and Physiology, 2009Co-Authors: L. N. Zibareva, Laurence Dinan, Jeanpierre Girault, Valentina I Yeriomina, Nyamjav Munkhjargal, René LafontAbstract:The phytoecdysteroid profiles of extracts of aerial parts of flowering plants of 7 ecdysteroid-containing species in the genus Silene (Caryophyllaceae; S. fridvaldszkyana Hampe, S. gigantea L., S. graminifolia Otth, S. mellifera Boiss. & Reuter, S. repens Patr., S. schmuckeri Wettst., and S. sendtneri Boiss.) have been examined and identified by HPLC and, in the case of two new compounds, by mass spectrometry and NMR. S. frivaldszkyana was found to contain predominantly 20-hydroxyecdysone (20E), with smaller amounts of 2-deoxyecdysone (2dE), 2-deoxy-20-hydroxyecdysone (2d20E), polypodine B (polB), integristerone A (IntA), 26-hydroxypolypodine B (26polB), and 20,26-dihydroxyecdysone (20,26E). Additionally, a new minor ecdysteroid, 26-hydroxyintegristerone A, has been identified from this species. S. gigantea contains 3 major Ecdysteroids (2dE, 2d20E, and 20E) and much smaller amounts of intA and 2-deoxy-20-hydroxyecdysone 25-β-D-glucoside, which is a new ecdysteroid. Ecdysteroids in the other 5 species have been identified by co-chromatography with reference compounds on RP- and NP-HPLC systems. There is considerable variability with regard to ecdysteroid profiles within the genus Silene. The chemotaxonomic value of ecdysteroid profiles within the genus Silene is discussed. © 2009 Wiley Periodicals, Inc.
-
Distribution of phytoEcdysteroids in the Caryophyllaceae.
Phytochemistry, 2003Co-Authors: L. N. Zibareva, René Lafont, Tamara Savchenko, Pensri Whiting, Vladimir A. Volodin, Zyadilla Saatov, Laurence DinanAbstract:Abstract Certain genera within the Caryophyllaceae (especially Silene and Lychnis) have received a significant amount of attention with regard to the isolation and identification of Ecdysteroids. However, the taxonomy of this family is difficult. Hence, the occurrence of phytoEcdysteroids in members of the Caryophyllaceae is presented, and combined with new data on ecdysteroid agonist (phytoecdysteroid) and antagonist activities, in order to survey the distribution of phytoecdysteroid-containing species within this large family, and to assess the utility of phytoEcdysteroids as chemotaxonomic markers. The new data presented (representing ca. 110 species) have been obtained by the application of sensitive biological/biochemical methods for the detection of ecdysteroid agonists and antagonists, using Drosophila melanogaster BII bioassay and ecdysteroid-specific immunoassays. In the antagonist version of the BII bioassay, only weak ecdysteroid antagonist activities were detected in a few of the extracts. From both new and previously available data, it was found that phytoEcdysteroids were present predominantly in the Genera Lychnis, Petrocoptis, Sagina and Silene. Comparison of ecdysteroid occurrence with a molecular phylogeny for the tribe Sileneae [Taxon 44 (1995) 525] revealed close association of ecdysteroid occurrence with certain groups of this tribe. In 14 species of Silene examined, there is a reasonable, but not absolute, relationship between the presence of Ecdysteroids in the seeds and in other plant parts. Where Ecdysteroids are present in the plant, highest concentrations are generally present in the roots.
Yoshiro Nakajima - One of the best experts on this subject based on the ideXlab platform.
-
cloning and expression of the ecdysteroid receptor during ecdysis and reproduction in females of the soft tick ornithodoros moubata acari argasidae
Insect Molecular Biology, 2007Co-Authors: Mari Horigane, Yoshiro Nakajima, Kazumasa Ogihara, T Shinoda, Demar TaylorAbstract:Molecular mechanisms of ecdysteroid regulation in development and reproduction have been thoroughly investigated in Diptera and Lepidoptera, but few studies report the molecular actions of Ecdysteroids in hemimetabolous insects and more primitive arthropods. Ecdysteroids appear to be the main hormones regulating development and vitellogenesis in ticks. An ecdysteroid receptor that showed high homology with EcRs of other arthropods was isolated from Ornithodoros moubata (OmEcRA). OmEcR expression patterns coincided with ecdysteroid titres in the haemolymph during moulting and vitellogenesis and differed between mated and virgin females. Therefore, OmEcR appears to mediate the regulation of moulting and vitellogenesis by Ecdysteroids in O. moubata females as seen in other arthropods.
-
ecdysteroid hormone titer and its relationship to vitellogenesis in the soft tick ornithodoros moubata acari argasidae
General and Comparative Endocrinology, 2007Co-Authors: Kazumasa Ogihara, Yoshiro Nakajima, Mari Horigane, Atsuko Moribayashi, Demar TaylorAbstract:A blood meal is required for reproduction in most argasid female ticks. The blood meal appears to stimulate an organ in the posterior end to produce a fat body stimulating factor (FSF), which is thought to be an ecdysteroid, to induce vitellogenin (Vg) synthesis. In this study, the relationship of vitellogenesis and Ecdysteroids was investigated by measuring Vg and ecdysteroid titers while observing oocyte development and oviposition in mated and virgin females. Oviposition occurred from day 10 after engorgement in mated females and continued up to 40-50 days, whereas egg maturation and oviposition did not occur in virgin females. Vg titers in the hemolymph peaked on day 6 after engorgement and subsequently declined in mated females. Interestingly, Vg synthesis occurred and ovarian development progressed to the development of early vitellogenic oocytes in virgin females but oocyte maturation and oviposition did not occur. Topical application of Ecdysteroids induced oviposition in fed virgin females indicating that Ecdysteroids may induce oviposition. Concentrations of Ecdysteroids for 20 days after engorgement revealed several peaks in mated female whole body extracts, but no peaks in virgin female extracts. In the hemolymph of only mated females, ecdysteroid titers showed two peaks that followed the early peak of Ecdysteroids in the whole body on day 4 and 6 after engorgement. In addition, Ecdysteroids in the reproductive tissues increased with the development of the ovary in mated females and this increase coincided with the latter peaks of the whole body. These observations indicate that physiological elevation of Ecdysteroids accelerate Vg synthesis, and may induce egg maturation and stimulate oviposition in fed mated Ornithodoros moubata females.
