Sexual dimorphism in developmental rate and ecdysteroid titre in Orgyia postica

Gu, Shi‐Hong; Tsai, R. S.; Chow, Yien Shing; Lin, Fei-Jann

doi:10.1016/0022-1910(92)90013-4

Cited by 15 publications

(5 citation statements)

References 18 publications

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“…In these species, injection of 20E into males does not induce vitellogenin synthesis (unpublished results), suggesting that the EcR-complex is not regulated in the same way as in flies. In the moth Orgyia postica, a species in which females have five larval instars while males have four, quantitative and qualitative sexual differences in ecdysteroid titre have been measured in larval life (Gu et al, 1992). In contrast, Tawfik et al (1997) found that gregarious males of Schistocerca gregaria differed from the females by the domination of 20E (94%), while in females the ratio 20E:E was about 50%.…”

Section: Ecdysteroid Titres In Adults Males: the Black Boxmentioning

confidence: 99%

Ecdysteroids: the overlooked sex steroids of insects? Males: the black box

Loof

2006

Insect Science

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The paradigm, still around in textbooks, that ‘in insects sex is strictly genetic, thus that they do not have sex hormones’, is mainly based on a wrong interpretation of the ‘gynandromorph argument’. It is no longer tenable. Given the fact that vertebrates and invertebrates probably had a common, sexually reproducing ancestor, there is no reason to assume that only vertebrates need sex hormones. The major function of sex hormones is to inform the somatoplasm about developmental changes that take place in the gonads. In contrast to juvenile hormone and neuropeptides, ecdysteroids meet all criteria to act as sex hormones, which was probably their ancient role. Their much better documented role in moulting and metamorphosis was a secondary acquisition that enabled arthropods to cope with growth problems, imposed by a rigid cuticle. Female insects use 20‐hydroxyecdysone (20E), secreted by the follicle cells of the ovary, in a similar way as females of egg‐laying vertebrates use estrogens. For a variety of reasons, the possibility that ecdysteroids, in particular ecdysone (E), might also act as sex hormones in male insects, thus as the counterpart of testosterone of vertebrates, has been very much overlooked. Thanks to the recent discovery of the molecular basis of the haploid‐diploid system of sex determination in the honeybee, the characterization of Halloween genes, proteomics, RNAi and so on, it now becomes possible to verify whether in insects, as with vertebrates, males are the endocrinologically default gender form.

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Section: Ecdysteroid Titres In Adults Males: the Black Boxmentioning

confidence: 99%

Ecdysteroids: the overlooked sex steroids of insects? Males: the black box

Loof

2006

Insect Science

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“…It is noteworthy that differential regulation of two ecdysteroids occurs in the lepidopteran, Orgyia postica, suggesting that ecdysteroid isoforms may also have different functions through development and between the sexes. However, no such functions have been defined (Gu et al, 1992). Although no distinct roles for JH isoforms have been demonstrated, differences in carrier binding, rates of production and rates of degradation suggest that JH isoforms are differentially regulated in both Diptera and Lepidoptera.…”

Section: Identification and Functions Of Jh Isoformsmentioning

confidence: 99%

Characterisation of juvenile hormone esterase in Drosophila melanogaster

Campbell

Healy

Oakeshott

1992

Insect Biochemistry and Molecular Biology

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Juvenile hormone (JH) is one of the main morphogenic hormones of insects and degradation of the hormone is believed to play an important role in its regulation in many insects. The two main routes for JH degradation are hydroy sis by JH esterase (JHE) and JH epoxide hydrolase (JHEH). • A major focus of research has been on juvenile hormone esterase (JHE) found in the haemolymph of final instar lepidopteran larvae, although considerable hydrolysis of JH occurs in other tissues and at other life stages. In contrast, no comprehensive study of JH degradation has been undertaken in any dipteran species. However, the available evidence suggests that very little JH degrading activity is found in the haemolymph of Diptera and several dipteran JHEs exhibit atypical patterns of sensitivity to inhibitors. These data suggested that both the expression pattern and the biochemical properties of dipteran JH degrading enzymes may differ from other insect orders, and therefore, that the role of JH degradation may be different.The aim of this project was to comprehensively characterise JH degradation in the dipteran, Drosophila melanogaster, with special emphasis on JHE. The first objective was to identify the JH degrading enzymes of D . melanogaster and the second was to deterrnine their expression patterns and biochemical properties in order to determine thei~ role in the regulation of JH titre. These data were compared with other data to deterrnine whether a general model could be developed for dipteran JH titre regulation. Finally, the roles of JH hydrolysis in the regulation of JH titre were compared among Diptera, Lepidoptera and other insects.Two approaches were taken to identify the JH degrading enzymes of D. melanogaster. The first was to investigate the properties of an esterase, denoted EST20, which can be visualised after native polyacrylarnide gel electrophoresis using artificial esterase substrates, a-and B-naphthylacetate. EST20 is shown to be a likely homologue of the p-esterase of Drosophila virilis, which has been claimed to be the JHE of this species. However, this study shows that JH hydrolytic activity is associated with neither EST20 in D. melanogaster nor the p-esterase in D . virilis.The second approach was to use a radiometric assay which identified two JH hydrolysing enzymes, JHE and JHEH. The developmental profile of JH hydrolytic activity in D. melanogaster correlates inversely with profiles of JH titre and production. Key features are prewandering and prepupal maxima of JH hydrolytic activity in whole body homogenates of final instar larvae. This developmental profile of expression is similar to the lepidopteran pattern suggesting that the role of JH hydrolysis is essentially similar during this period. In D. melanogaster, the prewandering maximum consists mainly of JHEH whereas the prepupal peak consists mainly of JHE. However, the relative contributions of JHE and JHEH at these times differs both among the Diptera and in other orders.JHE from the prepupal stage was purified to homogeneity by selectiv...

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“…1 ) [3] , [4] . This sexual difference in photoperiodic response is very unique among many moth species because the sexual dimorphism of other moths is genetically determined [5] , [6] , [7] , [8] . In the adult stage, flight-capable, long-winged females of O. thyellina are produced from larvae reared at a long photoperiod, while flightless, short-winged females are formed at a short photoperiod.…”

Section: Introductionmentioning

confidence: 99%

An FXPRLamide Neuropeptide Induces Seasonal Reproductive Polyphenism Underlying a Life-History Tradeoff in the Tussock Moth

et al. 2011

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The white spotted tussock moth, Orgyia thyellina, is a typical insect that exhibits seasonal polyphenisms in morphological, physiological, and behavioral traits, including a life-history tradeoff known as oogenesis-flight syndrome. However, the developmental processes and molecular mechanisms that mediate developmental plasticity, including life-history tradeoff, remain largely unknown. To analyze the molecular mechanisms involved in reproductive polyphenism, including the diapause induction, we first cloned and characterized the diapause hormone-pheromone biosynthesis activating neuropeptide (DH-PBAN) cDNA encoding the five Phe-X-Pro-Arg-Leu-NH2 (FXPRLa) neuropeptides: DH, PBAN, and α-, β-, and γ-SGNPs (subesophageal ganglion neuropeptides). This gene is expressed in neurosecretory cells within the subesophageal ganglion whose axonal projections reach the neurohemal organ, the corpus cardiacum, suggesting that the DH neuroendocrine system is conserved in Lepidoptera. By injection of chemically synthetic DH and anti-FXPRLa antibody into female pupae, we revealed that not only does the Orgyia DH induce embryonic diapause, but also that this neuropeptide induces seasonal polyphenism, participating in the hypertrophy of follicles and ovaries. In addition, the other four FXPRLa also induced embryonic diapause in O. thyellina, but not in Bombyx mori. This is the first study showing that a neuropeptide has a pleiotropic effect in seasonal reproductive polyphenism to accomplish seasonal adaptation. We also show that a novel factor (i.e., the DH neuropeptide) acts as an important inducer of seasonal polyphenism underlying a life-history tradeoff. Furthermore, we speculate that there must be evolutionary conservation and diversification in the neuroendocrine systems of two lepidopteran genera, Orgyia and Bombyx, in order to facilitate the evolution of coregulated life-history traits and tradeoffs.

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Sexual dimorphism in developmental rate and ecdysteroid titre in Orgyia postica

Cited by 15 publications

References 18 publications

Ecdysteroids: the overlooked sex steroids of insects? Males: the black box

Ecdysteroids: the overlooked sex steroids of insects? Males: the black box

Characterisation of juvenile hormone esterase in Drosophila melanogaster

An FXPRLamide Neuropeptide Induces Seasonal Reproductive Polyphenism Underlying a Life-History Tradeoff in the Tussock Moth

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