Purification, characterisation and titre of the haemolymph juvenile hormone binding proteins from Schistocerca gregaria and Gryllus bimaculatus

Tawfik, Azza A.; Kellner, Roland; Hoffmann, Klaus H.; Lorenz, Matthias

doi:10.1016/j.jinsphys.2005.11.005

Cited by 27 publications

(21 citation statements)

References 61 publications

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“…Furthermore, Hex-2 has a long hydrophilic insertion plus several protease-cleavage-like sites that are consistent with hexamerin receptors (Zhou et al, 2006b). Thus, when taking these characteristics into consideration, along with previous RNAi results (Zhou et al, 2006a) and JH-binding functions known for other insect hexamerins (Braun and Wyatt, 1996;Tawfik et al, 2006), it is not unreasonable to hypothesize that these two proteins cooperate to sequester JH and modulate its efficacy. In a broader context, these unique proximate characteristics support the idea that hexamerins have been co-opted in termites to ultimately inhibit irreversible morphogenesis towards the soldier caste.…”

Section: Termite Hexamerins and Impending Issuesmentioning

confidence: 99%

“…Hexamerins of solitary insects are normally involved in nutrient storage and nutritional signaling (Burmester and Scheller, 1999), but have also been authenticated as bona fide JH-binding proteins (Braun and Wyatt, 1996;Gilbert et al, 2000;Tawfik et al, 2006). One hypothesis for termite hexamerins is that they serve as a signaling mechanism for nutritional status and that pre-soldier differentiation is suppressed when certain nutritional requirements are met (Zhou et al, 2006a).…”

Section: Introductionmentioning

confidence: 99%

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Hexamerin-based regulation of juvenile hormone-dependent gene expression underlies phenotypic plasticity in a social insect

2007

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Worker termites of the genus Reticulitermes are temporally-arrested juvenile forms that can terminally differentiate into adultsoldier-or reproductive-caste phenotypes. Soldier-caste differentiation is a developmental transition that is induced by high juvenile hormone (JH) titers. Recently, a status quo hexamerin mechanism was identified, which reduces JH efficacy and maximizes colony fitness via the maintenance of high worker-caste proportions. Our goal in these studies was to investigate more thoroughly the influences of the hexamerins on JH-dependent gene expression in termite workers. Our approach involved RNA interference (RNAi), bioassays and quantification of gene expression. We first investigated the expression of 17 morphogenesis-associated genes in response to RNAi-based hexamerin silencing. Hexamerin silencing resulted in significant downstream impacts on 15 out of the 17 genes, suggesting that these genes are members of a JH-responsive genomic network. Next, we compared gene-expression profiles in workers after RNAi-based hexamerin silencing to that of (i) untreated workers that were held away from the colony; and (ii) workers that were also held away from the colony, but with ectopic JH. Here, although there was no correlation between hexamerin silencing and colony-release effects, we observed a significant correlation between hexamerin silencing and JHtreatment effects. These findings provide further evidence supporting the hypothesis that the hexamerins modulate JH availability, thus limiting the impacts of JH on termite caste polyphenism. Results are discussed in a context relative to outstanding questions on termite developmental biology, particularly on regulatory gene networks that respond to JH-, colony-and environmental-cues.

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Section: Termite Hexamerins and Impending Issuesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hexamerin-based regulation of juvenile hormone-dependent gene expression underlies phenotypic plasticity in a social insect

2007

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“…The protein content in the collected fractions was estimated using the RotiNanoquant assay (Roth, Karlsruhe, Germany) as described (Lorenz, 2003) and aliquots of each fraction were analysed by polyacrylamide gel electrophoresis under denaturing conditions (SDS-PAGE; Laemmli, 1970). A 3 % stacking gel containing 75 mM Tris-HCl (pH6.8) followed by a 10 % separating gel containing 375 mM Tris-HCl (pH 8.8) was used as described in Tawfik et al (2006). Vitellogenin was identified due to its relative molecular weight as determined by SDS-PAGE.…”

Section: Purification Of Vitellogenin and Production Of Antiserummentioning

confidence: 99%

“…The polyclonal rabbit antibody against Apis vitellogenin was custom prepared by Pineda Anikçrper-Service (Berlin, Germany) according to the standard protocol (see Tawfik et al, 2006 for details).…”

Section: Purification Of Vitellogenin and Production Of Antiserummentioning

confidence: 99%

“…The primary antiserum (rabbit-anti-Apis-Vg) was used at a 5000-fold dilution, the secondary antibody (goat anti rabbit immunoglobuline alkaline phosphatase conjugate A 3937; Sigma-Aldrich, Taufkirchen, Germany) was diluted 15000-fold. For details on the incubation and rinsing steps see Tawfik et al (2006).…”

Section: Analysis Of Proteins In Nurse Bee Hemolymph (Vitellogenin Tmentioning

confidence: 99%

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Physiological consequences of prolonged nursing in the honey bee

2008

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Honey bee workers normally produce brood food at an age of 5 to 15 days. However, natural events like swarming or brood diseases may lead to the occurrence of over-aged nurses. Here we investigated the physiological consequences of prolonged nursing for both the nurses and the brood they rear, and tried to separate the effects of chronological age and of task affiliation on some important physiological parameters. Brood was reared in groups of colonies with either a normal age structure or with moderately over-aged workers. The haemolymph concentrations of total protein and vitellogenin, the development of mandibular and hypopharyngeal glands, and the activity of a-glucosidase in the hypopharyngeal glands of nurses from these groups of colonies were compared. Moreover, we used the fertility of young workers reared by normal-and overaged nurses as a bioindicator for the quality of the brood care they had received. It showed that parameters linked to the production of brood food proteins remained stable in over-aged nurses, whereas the development of mandibular glands regressed. Workers reared by over-aged nurses had more ovarioles and showed stronger ovary development under queenless conditions. Our results indicate that while over-aged nurses remain capable of producing brood food, they are not functionally equivalent to young nurses. The partial degeneration of the mandibular glands normally occurring at the end of the nursing period cannot be prevented by prolonged nursing. The distinct phenotype of workers reared by old nurses raises the question of possible age-related specialisations among nurses in colonies with a normal age structure.

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Age-dependent cyclic locomotor activity in the cricket, Gryllus bimaculatus, and the effect of adipokinetic hormone on locomotion and excitability

2010

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Excitability and locomotor activity of male and female last instar larvae and adults of the two-spotted cricket are measured under crowded conditions, allowing the animals to interact with conspecifics during observations. Male and female last instar larvae display age-dependent cyclic patterns of activity with maxima during early to mid scotophase and minima during early photophase. A period of low locomotor activity without time of day-dependent cyclic changes starts 1 day before the final moult and lasts until 1 day after the moult. Then, both excitability and locomotor activity increase and become cyclic again within 2 or 3 days. The cyclic changes gradually dampen in adult females older than 6 days and finally cease. When injected into photophase larvae and adults, adipokinetic hormone (AKH) increases excitability and locomotor activity in a dose-dependent manner, whereas it has no such effect when injected into scotophase animals. Other behaviours (jumping, hind wing trembling) that mostly occur in scotophase crickets are also increased by injecting AKH into photophase crickets. We argue that AKH could be responsible for linking the endogenous clock output with the cyclic changes in locomotor activity. Furthermore, AKH may serve to synchronise metabolism and behaviour to optimise larval development and reproduction.

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Purification, characterisation and titre of the haemolymph juvenile hormone binding proteins from Schistocerca gregaria and Gryllus bimaculatus

Cited by 27 publications

References 61 publications

Hexamerin-based regulation of juvenile hormone-dependent gene expression underlies phenotypic plasticity in a social insect

Hexamerin-based regulation of juvenile hormone-dependent gene expression underlies phenotypic plasticity in a social insect

Physiological consequences of prolonged nursing in the honey bee

Age-dependent cyclic locomotor activity in the cricket, Gryllus bimaculatus, and the effect of adipokinetic hormone on locomotion and excitability

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