Identification of a juvenile hormone-like compound in a crustacean.
09 Jan 1987-Science (American Association for the Advancement of Science)-Vol. 235, Iss: 4785, pp 202-205
TL;DR: Results indicate that JH-like compounds such as methyl farnesoate have regulatory roles in crustaceans.
Abstract: Juvenile hormone (JH) has central roles in the regulation of insect development and reproduction but has not previously been identified in other arthropod classes. The hemolymph of a crustacean, Libinia emarginata (Leach), has now been analyzed for JH-like compounds. Samples contained 0.003 to 0.030 nanogram of JH III per milliliter and 10 to 50 nanograms of methyl farnesoate per milliliter; methyl farnesoate is a compound structurally related to JH III that has JH bioactivity. Several tissues were examined for synthesis and secretion of JH-like compounds. Of these tissues, only the mandibular organs produced and secreted JH III and methyl farnesoate. However, microchemical analysis revealed that this JH III was racemic, and thus likely an artifactual oxidation product of methyl farnesoate. Secretion of methyl farnesoate was related to reproduction in females, with the highest rates observed in Libinia near the end of the ovarian cycle when oocyte growth and vitellogenesis are greatest. These results indicate that JH-like compounds such as methyl farnesoate have regulatory roles in crustaceans.
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TL;DR: Little advance has occurred in understanding the rationale for the diversity of growth patterns, and computer modelling offers promise, but is constrained by lack of data on natural mortality for validation.
Abstract: Developments during the past 20 years are reviewed for four aspects of crustacean growth. These are the hormonal control of moulting, the effects of external factors on growth rate, the patterns of growth and the determination of age. Hormonal control. The nature and structure of Moult Inhibiting Hormone has been determined, though the mechanism by which it inhibits crustecdysone production is still unclear. A role in moult control by Crustacean Hyperglycaemic Hormone has been demonstrated, but needs clarification. Methyl farnesoate, a juvenile hormone like substance, occurs in Crustacea: however, a clear function as a juvenile hormone has yet to be shown. External factors. The effect of increased temperature in reducing moult increments is supported by further data. Reduced food supply causes smaller moult increments and longer intermoult periods: the latter effect is generally proportionately greater. A role for CHH in this process is hypothesised. Patterns of growth. Little advance has occurred in understanding the rationale for the diversity of growth patterns. Computer modelling offers promise, but is constrained by lack of data on natural mortality for validation. Determination of age. The basic methods available remain size frequency analysis and tagging programmes. There have been advances in technology and methods of analysis, but no major breakthrough. Novel methods include radionuclide ratios (expensive, complex and give only duration of current intermoult), lipofuschin pigment assay (promising, but needs further validation), and annular structures in the infra-cerebral organ (still very speculative).
314 citations
Cites background from "Identification of a juvenile hormon..."
...It has now been demonstrated that a JH-like substance, methyl farnesoate, is produced by the mandibular organ in crustaceans, the initial identification being in the spider crab Libinia emarginata (Laufer et al., 1987a)....
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...It has also been clearly shown that production of methyl farnesoate by the mandibular organ is inhibited by an eyestalk factor (MOIH) (Laufer et al., 1987b; Wainwright et al., 1996)....
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...The latter is also a function of methyl farnesoate in crustaceans, and most of the observations of its activity in crustaceans relate to that aspect of its physiological role (Hinsch, 1980; Borst et al., 1987; Laufer et al., 1987a; Laufer et al., 1993)....
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TL;DR: The current review has tried to recapitulate recent studies on the role of gonadal regulatory factors in regulating crustacean reproduction.
Abstract: Control of reproductive development in crustaceans requires neuropeptides, ecdysone and methyl farnesoate (MF). A major source of neuropeptides is the X-organ–sinus gland (XO–SG) complex located in the eyestalk ganglia of crustaceans. The other regulatory factors (either peptides or neuromodulators) are produced in the brain and thoracic ganglia (TG). Two other regulatory non-peptide compounds, the steroid ecdysone and the sesquiterpene MF, are produced by the Y-organs and the mandibular organs, respectively. In the current review, I have tried to recapitulate recent studies on the role of gonadal regulatory factors in regulating crustacean reproduction.
* AG
: androgenic gland
AGH
: androgenic gland hormone
cAMP
: cyclic adenosine monophosphate
CHH
: crustacean hyperglycemic hormone
DA
: dopamine
dsRNAi
: double-stranded RNA interference
EPA
: eicosapentaenoic acid
ESA
: eyestalk ablation
FA
: farnesoic acid
FA-O-MeT
: farnesoic acid O -methyl transferase
FSH
: follicle stimulating hormone
GIH
: gonad inhibitory hormone
GSF
: gonad stimulating factor
HCG
: human chorionic gonadotrophin
HP
: hepatopancreas
HPLC
: high performance liquid chromatography
5-HT
: 5-hydoxytryptamine
JH
: juvenile hormone
LH
: luteinizing hormone
MeVg1
: Metapenaeus ensis Vg1
MF
: methyl farnesoate
MIH
: molt inhibiting hormone
MO
: mandibular organ
MS
: mass spectroscopy
OA
: octopamine
PG
: prostaglandin
SG
: sinus gland
SP
: spiperone
TG
: thoracic ganglia
Vg
: vitellogenin
VIH
: vitellogenesis inhibiting hormone
257 citations
Cites background from "Identification of a juvenile hormon..."
...Unilateral and bilateral ESA enhances MF levels and increases the ovarian index in L. emarginata (Laufer et al., 1987)....
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...MF is a sesquiterpene discovered in the mandibular organ (MO; Fig.2D,E,F) of crustaceans about 20 years ago (Borst et al., 1987; Laufer et al., 1987)....
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...In vitro, MF production has been associated with ovarian development in C. maenas, L. emarginata and U. pugilator (Borst et al., 1987; Laufer et al., 1987)....
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TL;DR: This article provided an up-to-date review of the literature on the historical development of the field of "crustacean eyestalk hormones", and the names CHH, MIH, and GIH/VIH (gonad/vitellogenesis-inhibiting hormone), MOIH (mandibular organ-inhibititing hormone) were coined.
249 citations
TL;DR: Several heavy metals were able to produce hyperglycemia in crustaceans during short times of exposure; while a hypoglycemic response was noted after longer exposures, due to inhibition of secretion of the crustacean hyperglycemic hormone.
Abstract: The main endocrine-regulated processes of crustaceans have been reviewed in relation to the effects of endocrine-disrupting compounds (EDCs). Molting has been shown to be inhibited by several organic pollutants, such as xenoestrogens and related compounds, as well as by some pesticides. Most of these disrupters are thought to interfere with ecdysone at target tissues, although only for a few has this action been demonstrated in vitro. The heavy metal cadmium appears to inhibit some ecdysone secretion. Juvenoid compounds have also been shown to inhibit molting, likely by interfering with the stimulatory effect of methyl farnesoate. A molt-promoting effect of emamectin benzoate, a pesticide, has also been reported. As for reproduction, a variety of organic compounds, including xenoestrogens, juvenoids and ecdysteroids, has produced abnormal development of male and female secondary sexual characters, as well as alteration of the sex ratio. Cadmium and copper have been shown to interfere with hormones that stimulate reproduction, such as methyl farnesoate, as well as with secretion of the gonad inhibiting hormone, therefore affecting, for example, ovarian growth. Several heavy metals were able to produce hyperglycemia in crustaceans during short times of exposure; while a hypoglycemic response was noted after longer exposures, due to inhibition of secretion of the crustacean hyperglycemic hormone. The ecological relevance of EDCs on crustaceans is discussed, mainly in relation to the identification of useful biomarkers and sentinel species. New experimental approaches are also proposed.
238 citations
Cites background from "Identification of a juvenile hormon..."
...On the other hand, the juvenile hormone (JH) of crustaceans, i.e., methyl farnesoate (MF, Laufer et al., 1987) is a sesquiterpenoid compound (the unepoxidated form of JHIII of insects), secreted by themandibular organs, whose secretion is inhibited by the eyestalk hormoneMOIH....
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Journal Article•
TL;DR: A. Vitellogenesis control, timing of the reproductive cycle: duration and relation with the molting cycle 227, and ways of action.
Abstract: 1. General considerations 221 2. Origin of vitellogenin 222 3. Vitellogenin uptake by vitellogenic ovaries 223 a) Transformation and role of the follicle envelope 223 b) Vitellogenic oocyte and endocytosis mechanism 224 4. From vitellogenin to vitellin: a processing? 224 5. Vitellogenin synthesis and vitellogenin level in haemolymph as means for monitoring vitellogenesis 226 6. Timing of the reproductive cycle: duration and relation with the molting cycle 227 B. Vitellogenesis control 229 1. Inhibitory control by VIH (Vitellogenesis Inhibiting Hormone) 229 a) The X organ-sinus gland complex 229 Eyestalked species Eyestalkless species b) Ways of action 230 Control of vitellogenin synthesis Control of vitellogenin uptake by the oocytes c) Extraction and purification of VIH 231 d) Latest data on VIH 231 2. Stimulatory control 233 a) Neurohumoral factors 234 b) Vitellogenin Stimulating Ovarian Hormone (VSOH) 234 c) Ecdysteroids 234 d) Juvenoids 235 e) Ovary-stimulating factor from males 237
236 citations
References
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TL;DR: In this paper, the use of rank sums from a combined ranking of k independent samples in order to decide which populations differ is suggested as a convenient alternative to making separate rankings for each pair of samples and the two methods are compared.
Abstract: This paper considers the use of rank sums from a combined ranking of k independent samples in order to decide which populations differ. Such a procedure is suggested as a convenient alternative to making separate rankings for each pair of samples, and the two methods are compared. Asymptotic use of the normal tables is given and the treatment of ties is discussed. A numerical example is given.
3,305 citations
TL;DR: It is proposed that the described method may be usefully employed to assess the physiological changes in the enzymic competence of the glands to effect the last two stages in C(16) juvenile hormone biosynthesis.
Abstract: The rate at which isolated corpora allata of adult female Schistocerca gregaria incorporate [3H]farnesenic acid and [14C]methionine into C16juvenile hormone in vitro was examined at different concentrations of farnesenic acid, methionine, O2 and H+ ions. Maximum juvenile hormone biosynthesis is obtained at a farnesenic acid concentration of 20μm. The range of optimum l-methionine concentrations (0.1–0.4mm) encompasses the physiological concentration of this substrate in the haemolymph. Hormone biosynthesis is dependent on O2, but is not stimulated by hyperbaric oxygen tension. The glands had a maximum synthetic activity at pH8.0, but their activity was more reproducible in the the physiological range pH7.0–7.5. At pH6.5 and less, the synthetic ability was considerably decreased. The relative incorporations of the labelled substrates into methyl farnesoate and C16 juvenile hormone indicate that [3H]farnesenic acid comes into isotopic equilibrium within the gland more rapidly than [14C]methionine. The incorporations into methyl farnesoate become stoicheiometric after 20min incubation and into C16 juvenile hormone after a further 10min. Labelled juvenile hormone is detectable after 10min incubation and the rate of incorporation is constant for up to 4h. It is proposed that the described method may be usefully employed to assess the physiological changes in the enzymic competence of the glands to effect the last two stages in C16 juvenile hormone biosynthesis.
293 citations
TL;DR: In this article, the authors propose a method to solve the problem of the problem: this article...,.. ].. ).. ]... )...
Abstract: CONTENTS
283 citations
TL;DR: Experiments show that on suddenly releasing the tension of the muscle during a tetanus, the tension always redevelops in a manner similar to the development of tension in the quick contraction, even though the tetanus be developed initially by the slow contraction.
Abstract: 1. A brief account is given of the present position of the problem of neuromuscular action in the Crustacea. 2. A method is described by which the leg of Carcinus maenas may be perfused and stimulated. By this method the muscle remains in good condition for some 8 hours. 3. By stimulating the nerve in Carcinus leg with alternating currents of increasing intensity a series of varied responses is obtained. Above the threshold a contraction is developed of a comparatively slow type. With increase of intensity of the stimulus the response fails, owing to the excitation of inhibitory nerves. But at still greater intensities contraction reappears. This contraction, however, is very rapid. Tetani developed from the slow contraction are easily inhibited. Tetani developed from the rapid contraction cannot be inhibited by superimposed stimuli. 4. The relation of the quick and slow contractions is considered. It is not possible to fatigue one without fatiguing the other. Experiments show that on suddenly releasing the tension of the muscle during a tetanus, the tension always redevelops in a manner similar to the development of tension in the quick contraction, even though the tetanus be developed initially by the slow contraction. The same contractile mechanism is involved in both cases. 5. The latent period of contraction on stimulation of the nerve is very long, and ranges from 300σ at the threshold. That for direct stimulation of the muscle is 7-1Oσ. Above the threshold the latent period shortens rapidly with increasing stimulus. Over this region the contractions are of the slow type. The latent period becomes asymptotic to 50σ as the intensity is increased. At this value the contractions are of the quick type. Inhibition is effective where the latent period begins to approach its asymptotic value. 6. It is suggested that all the varied phenomena observed are related to the power of summation of crustacean muscle; that the slow contraction in response to a battery of stimuli is not due to a different contractile mechanism from the quick one, but that it is a summation effect by which a statistically increasing number of muscle fibres are brought into action as successive impulses pass down the nerve.
201 citations
TL;DR: Two juvenile hormones are isolated from organ cultures of corpora allata of the tobacco hornworm moth, Manduca sexta Johannson, and are purified by high-resolution liquid chromatography and identified as methyl (2E, 6E)-(10R)-10,11-epoxy-3,7, 11-trimethyl-2,6-dodecadienoate, a new natural hormone.
Abstract: Two juvenile hormones are isolated from organ cultures of corpora allata of the tobacco hornworm moth, Manduca sexta Johannson, and are purified by high-resolution liquid chromatography. These are identified as methyl (2E, 6E)-(10R)-10,11-epoxy-3,7,11-trimethyl-2,6-dodecadienoate, a new natural hormone, and methyl (2E,6E) - (10R,11S) - 10,11 - epoxy - 3,7,11 - trimethyl-2,6-tridecadienoate. [14C]Methionine is incorporated only into their methoxycarbonyl group. Details of the in vitro techniques and the chemical proof of structures are presented. The significance of the occurrence of a new juvenile hormone and the new techniques used for production, isolation, and identification are discussed.
189 citations